Supersaurus timeline

July 17, 2019

The history of Supersaurus — and its buddies Ultrasauros and Dystylosaurus — is pretty complicated, and there seems to be no one source for it. But having read a lot about these animals in the process of writing eleven mostly pretty substantial posts about them, I feel like I’m starting to put it all together. This post is an attempt at recognising the landmarks in this history, in chronological order. Please leave a comment if you find a mistake or if I missed anything.


1943 — Sawmill operator Eddie Jones and his wife Vivian are prospecting for uranium during WWII. They find a brachiosaur skeleton in an advanced state of erosion at Potter Creek in the Uncompahgre Upwarp (Jensen 1987:592). (Jensen 1985a:697 says the humerus was also collected in this year, but that is contradicted by other accounts.)

1955 — Eddie and Vivian Jones collect the brachiosaur humerus and donate it to the Smithsonian Institition (George 1873b:53), where it is accessioned as USNM 21903 and put on display some time before March 1959 (Anonymous 1959).

USNM 21903, a left humerus of ?Brachiosaurus altithorax, discovered by Eddie and Vivian Jones. From the NMNH’s specimen gallery page, which gives the collection date as 1955. When I first saw this specimen, my gut reaction was that it was not slender enough to be Brachiosaurus, but note that the midshaft is very extensively restored. It may be that the intact bone was longer than the version we now see.

1958 — Jensen sees the Smithsonian humerus and finds the Jones family, who take him to the humerus location in Potter Creek and to three other Uncompahgre fossil localities (Jensen 1985a:697).

1964 — Jensen makes his first collection from the Uncompahgre Upwarp (Jensen 1985b:710).

1971 — Jensen sees a theropod toe bone at the Joneses’ home and asks where they found it. They tell him “On the Uncompahgre” (George 1973b:53), i.e. probably specifically from Dry Mesa, awakening his interest in that quarry.

1972 — In April (George 1973b:53), Jensen makes his first collection of material from Dry Mesa, one of the Uncompahgre localities found by the Joneses (Jensen 1985a:697).

In August (George 1973b:51-52) a large sauropod pelvis is found. This seems to have been the first element found that hinted at a very large sauropod at Dry Mesa (George 1973b:52-53).

Jensen displays the first Dry Mesa pelvis, still in the ground, in a frame from the 1976 version of The Great Dinosaur Discovery [13m53s].

Later this year, the first large Dry Mesa scapulocoracoid is found (Jensen 1985b:717). This would later be referred to as the “first specimen” of Supersaurus (e.g. Jensen 1985a:figure 8), but it was the subsequently discovered “second specimen” that would become the holotype when the genus was formally named (Jensen 1985a:701).

[NOTE. I am increasingly concerned that this might be wrong, and that the first scapulocoracoid found might after all have become the holotype. How to establish this? I sense yet another blog-post incoming.]

This is also the date given in the Dystylosaurus systematic palaeontology of Jensen (1985a:707). This may be an error as it is seven years before the date given for Supersaurus and Ultrasaurus, both of which names were known long before that of Dystylosaurus. but Curtice and Stadtman (2001:33) corroborate this early date for the discovery of the Dystylosaurus vertebra, and the relatively low specimen number BYU 4503 perhaps also suggests early collection and accessioning.

1973 — First published accounts of the giant sauropod material from Dry Mesa. The earliest may be that of Jean George (1973a) in the Denver Post’s Empire Magazine, on May 13. This is subsequently condensed into an account (George 1973b) in Reader’s Digest for June (not August as stated by Jensen 1985b:717, who also mis-cites the title). This latter account may be responsible for coining the informal name “Supersaurus” (Jensen 1985b:717), which would later be confirmed as the scientific name. (“There ‘Supersaurus,’ as we will call him, now awaits an official name and taxonomic classification.” — George 1973b:53.)

On Tuesday 13 November, a one-hour film about the dinosaurs of Dry Mesa, The Great Dinosaur Discovery, premieres in Delta, Colorado (Herald 1973). It is to be aired on 225 public TV stations across the USA.

Brigham Young University publishes an eight-page pamphlet, also titled The Great Dinosaur Discovery (House et al. 1973) to introduce the documentary. In it, Jensen is said to refer to the giant sauropod as “Big George”, but this nickname never caught on. “Both of Big George’s eight-foot-long shoulder blades were uncovered at the quarry” by this stage. The large pelvis is now considered probably not to belong to Big George. Jensen thinks the new specimen “will not only require a new genus and species, but also a new family and perhaps even a new infra-order”.

1974 — Jensen hopes that the Dry Mesa Quarry will be developed as a tourist destination along the lines of Dinosaur National Monument, “with provisions for public access and viewing while the scientific work continues” (Barnes 1974:40) — a dream that would never come to pass.

1976 — A shortened version of The Great Dinosaur Discovery is made available for schools. (At present, this is the only version we have access to.) In this version of the film (and presumably in the 1973 original, if the 1976 version was made only by cutting), the name “Supersaurus” is used informally, and a reconstruction of the animal [20 minutes in] shows it modelled after Brachiosaurus rather than a diplodocid.

A newspaper report about a large sauropod humerus (Anonymous 1976:1) suggests that Jensen believes belongs to “Supersaurus”. But no Supersaurus humerus is subsequently mentioned, and the bone probably belongs to another taxon. Its slenderness suggests it may belong to a brachiosaur: it is probably the Potter Creek humerus or more likely a cast of it, misreported.

1977 — Jensen is informally referring to the giant sauropod as “Supersaurus jenseni” (Look 1977:37). It is still felt that “it is a good guess that the big animal looked something like a cousin to the Brachiosaurus“.

“Late 1970s” — Dale McInnes prepares the “2nd specimen” Supersaurus scapulocoracoid, probably referring to the second to be discovered, which we believe is BYU 9025, eventually to become the holotype. (The “1st specimen” has already been prepared by this point.) In the 11-foot-long jacket, they find 9’2″ of bone, which they reduce to an 8’10” scapulocoracoid by closing cracks.

1978 — John Ostrom’s (1978) popular account of new ideas about dinosaurs in National Geographic mentions Supersaurus, and still considers it probably “built along the lines of Brachiosaurus“. He says that “a pair of shoulder blades eight feet long” have been dug up, so both of the elements that might be the holotype were known by this point.

1978 — Olshevsky (1991:139) gives this as the date of Jensen’s first informal use of the name “Ultrasaurus”, but this must be considered suspect as other sources say the key specimen of this genus was not discovered until 1979.

1979 — The brachiosaurid scapulocoracoid BYU 9462 (BYU 5001 of Jensen’s usage) is discovered and collected from the Dry Mesa Quarry (Jensen 1987:603 — although in this passage he incorrectly says the specimen number is BYU 5000). The discovery is witnessed by a Japanese film crew that is making a documentary about the Dry Mesa dinosaurs (Jensen 1985b:717). Jensen begins to refer to the specimen informally as “Ultrasaurus”.

Miller et al. (1991: figure 4b). “Loading plaster-jacketed bones at the Dry Mesa quarry, 1979. Left to right, Richard Jensen, Jim Jensen, Japanese TV crew.” It’s obvious from the shape of the plaster jacket that this is the “Ultrasaurus” scapulocoracoid BYU 9462.

The earliest reports of “Ultrasaurus” appear in the media (Webster 1979, Whitney 1979, Martin 1979).

At the climax of an eleven-day lecture tour in Japan, Jensen presents casts of three bones to the the people of Japan (Anonymous 1979): the “Ultrasaurus” scapulocoracoid BYU 9462, the Potter Creek humerus USNM 21903 and a large rib referred to Brachiosaurus sp.

This is the date given in the Ultrasaurus systematic palaeontology of Jensen (1985a:704).

This is also the date given in the Supersaurus systematic palaeontology of Jensen (1985a:701): “COLLECTOR.—James A. Jensen 1979”. This late date is surprising, as Supersaurus material was known as early as 1972 and both scapulocoracoids had been excavated by the time of Ostrom’s (1978) account.

1982 — Last collection of material considered for 1985 descriptive paper (Jensen 1985a:697).

Wilford (1982), in a popular article in the New York Times apparently written with Jensen’s collaboration, says that Supersaurus “may be an enlarged variation of brachiosaurus” and that Ultrasaurus “must have been even larger”, indicating that Supersaurus may still have been thought of as brachiosaurid well after the discovery of Ultrasaurus.

1983 — As of this date, approximately 100 tons of material collected by Jensen for BYU remains unprepared (Jensen 1985a:709).

Kim (1983) names a Korean sauropod Ultrasaurus tabriensis, intending it to be a new species of Jensen’s genus. However, since the name Ultrasaurus has not previously been formally published, Kim inadvertently preoccupies the name. (The Korean sauropod was thought enormous because of the size of its “ulna”; however, this bone is clearly a humerus, and of only moderate size for a sauropod. The taxon is generally considered undiagnosable, and the name therefore a nomen dubium.)

1985 — Jensen’s main descriptive paper (Jensen 1985a) is published, formally naming three new sauropod genera. Supersaurus (now considered to be of indeterminate family) is based on the scapulocoracoid BYU 9025 (BYU 5500 of his usage); Ultrasaurus (considered to be a brachiosaurid) is based on the posterior dorsal vertebra BYU 9044 (BYU 5000 of his usage) rather than the scapulocoracoid; and Dystylosaurus (which “no doubt represents a new sauropod family”) is based on the anterior dorsal vertebra BYU 4503 (BYU 5750 of his usage). This paper is accompanied by a broader overview of the Uncompahgre dinosaur fauna (Jensen 1985b) in which he says of the second Supersaurus scapulocoracoid that “it displays diplodocid affinities” (p717).

1987 — Jensen’s second descriptive paper removes the large Dry Mesa cervical vertebra BYU 9024 (BYU 5003 of his usage) from Ultrasaurus and refers it to Supersaurus (Jensen 1987:600-602). It seems from this paper that he may have intended the Ultrasaurus scapulocoracoid BYU 9462 (BYU 5001) to be the holotype of that genus (Jensen 1987:603). By this point, Supersaurus seems to have been recognised as diplodocid: “two unusually large scapulocoracoids … were referrable to the Diplodocidae. One of these (BYU 5500, Fig. 9B) is the holotype of Supersaurus vivianae” (p602).

1988 — A second large pelvis, BYU 13018, is found in Dry Mesa quarry (Wakley 1988, Wilford 1988, Miller et al. 1991:40). This is quickly recognised as belonging to Supersaurus, and will later be formally referred to that genus (Curtice and Stadtman 2001:38-39). It is now on display at the North American Museum of Ancient Life.

1990 — In the landmark encyclopaedia The Dinosauria, McIntosh (1990) describes Supersaurus as a diplodocid (p391), Ultrasaurus (Jensen) as “a very large brachiosaurid” based on the type vertebra and referred scapulocoracoid (p384), and the Dystylosaurus vertebra as “clearly brachiosaurid” (p384).

1991 — McGowan (1991:118) originates the idea that Ultrasaurus massed 180 tonnes, based on its restoration as a brachiosaurid 1.32 times as large in linear dimension as the Berlin Giraffatitan brancai paralectotype MB.R.2181 (formerly HMN SII) whose mass Colbert (1962) had grossly overestimated at 78 tons.

Olshevsky (1991:139), recognising the preoccupation of the name Ultrasaurus by Kim’s (1983) genus, raises the replacement name Ultrasauros for Jensen’s genus, with Jensen’s blessing. He had originally suggested the replacement name Jensenosaurus, but Jensen disliked this and suggested the variant spelling that was used instead (Curtice et al. 1996:87-88).

Miller et al. (1991:40) suggest that the holotype dorsal vertebra of Ultrasaurus (i.e. Ultrasauros) might by diplodocid, due to its similarity to the sacral vertebrae of the 1988 pelvis whose tall neural spines “most closely resemble the diplodocids”.

1994John Sibbick’s classic artwork of Supersaurus and Ultrasaurus, with Seismosaurus, is published in David Norman’s Prehistoric Life: The Rise of the Vertebrates.

1995 — Curtice (1995), in an SVP abstract, reassigns to Supersaurus the clearly diplodocid caudal vertebra BYU 9045 (BYU 5002 of Jensen’s usage), which Jensen had assigned to Ultrasaurus.

The caudal vertebra BYU 9045 (BYU 5002 of Jensen’s usage), in (from left to right) posterior, right lateral, and anterior views. Modified from Jensen (1985a:figures 2E, 3E and 2D respectively), an including his original scalebars. These are consistent between the photos in posterior and lateral views, and if accurate indicate that the vertebra is 1.18 m in total height.

1996 — Curtice et al. (1996) persuasively show that the holotype of Ultrasauros, BYU 9044 (BYU 5000 of Jensen’s usage) is diplodocid, and conclude that it belongs to Supersaurus, making Ultrasauros a junior synonym.

2001 — Curtice and Kenneth (2001) show that the holotype of Dystylosaurus, BYU 4503 (BYU 5750 of Jensen’s usage) is diplodocid, and conclude that it, too, belongs to Supersaurus, making Dystylosaurus another junior synonym.

2003 — Curtice (2003), in a conference abstract, suggests tentatively that Supersaurus (into which he has already sunk Ultrasauros and Dystylosaurus) may itself be synonymous with Barosaurus.

2005 — A team from a the Wyoming Dinosaur Center announce in an SVP abstract and poster (Lovelace et al. 2005) a new specimen WDC DMJ-021 (“Jimbo”), which they refer to Supersaurus vivianae.

McIntosh (2005:73), in revising Barosaurus, is persuaded that Supersaurus is indeed a valid genus rather than merely a large species of Barosaurus. (He mentions “the type specimen, the right scapulocoracoid” — another puzzle piece to help determine which element is the type.)

2008 — The WDC team formally describe their referred Supersaurus specimen WDC DMJ-201 (“Jimbo”), providing a phylogenetic analysis that recovers Supersaurus (based on a compound BYU+WDC taxon) as more closely related to Apatosaurus than to Barosaurus.

2011 — Whitlock’s phylogenetic analysis of diplodocoids recovers Supersaurus as the most basal diplodocine (Whitlock 2011:figure 7), i.e. closer to Barosaurus than to Apatosaurus, but not very close to either.

2015 — Tschopp et al.’s phylogenetic analysis of diplodocoids codes the BYU and WDC Supersaurus individuals as separate OTUs and finds that they emerge as sister taxa (Tschopp et al. 2015:figure 118), corroborating Lovelace et al.’s referral of the WDC specimen to Supersaurus. They recover Supersaurus in a small clade with Australodocus and Dinheirosaurus near the base of diplodocinae: again, closer to Barosaurus than to Apatosaurus, but not very close to either.

2016 — In an SVPCA talk and abstract, Taylor and Wedel (2016) argue that BYU 9024, the large cervical vertebra usually considered to be part of the Dry Mesa Supersaurus, actually belongs to a large Barosaurus. If this is correct, then the concept of Supersaurus requires further revision.

2019 — In a seemingly endless series of blog-posts, Taylor and Wedel consider the history of Supersaurus and co., and the taxonomic implications of the BYU cervical belonging to Barosaurus.

References

Note: this is a unified bibliography for all the posts in the present series. It therefore includes references not cited in this post.

 

It’s time to revisit everyone’s favourite trio of apocryphal super-sized sauropods! (Yes, we’ve talked about this before, but only very briefly, and that was nearly eleven years ago. Things have moved on since then.)

John Sibbick’s classic artwork showing three giant sauropods, including two of Jensen’s three. On the left is Seismosaurus Gillette 1991, which is not directly relevant to today’s post. In the middle is the brachiosaur Ultrasaurus, and on the right the diplodocid Supersaurus. Poor, unloved Dystylosaurus doesn’t get a look-in — perhaps because this was drawn before that name had been announced?

Here’s the story so far …

1. Jensen’s discoveries

In a series of expeditions beginning in April 1972, following a tip from uranium prospectors Eddie and Vivian Jones, Jim Jensen found numerous massive sauropod fossils in the Dry Mesa quarry, southwest Colorado. The Supersaurus pelvis at least was still in the ground as late as August 1972 (George 1973b:51–52) and the excavations continued into 1982 (Jensen 1985:697).

Eschewing such pedestrian venues as Science, Nature or indeed the Journal of Vertebrate Paleontology, Jensen first told the world about these finds in the popular press. The oldest widely circulated work that mentions them is Jean George’s (1973b) piece in Reader’s Digest, condensed from the same author’s piece in the Denver Post’s Empire Magazine earlier that year (George 1973a).

“‘Supersaurus,’ as we shall call him, now awaits an official name and taxonomic classification”, wrote George (1973b:53) — but the piece does not mention the names “Ultrasaurus” or “Dystylosaurus” and I’ve not been able to determine when those informal names became known to the world. (Can anyone help?) We do know that Jensen was informally using the name “Ultrasaurus” as early as 1979 (Curtice et al. 1996:87).

Anyway, for reasons that have never been very clear, Jensen concluded that the remains represented not one, not two, but three gigantic new genera: a diplodocid, which he named “Supersaurus”; a brachiosaurid, which he named “Ultrasaurus”; and an unidentifiable which he named “Dystylosaurus”. All these names were informal at this point, like “Angloposeidon” and “The Archbishop”.

2. Kim’s accidental Ultrasaurus

After Jensen had been using these names informally for some years, Kim (1983) named an indeterminate Korean sauropod as Ultrasaurus tabriensis. Based on the abstract (the only part of the paper in English, apart from the figure captions), Kim was aware of Jensen’s dinosaurs: “Judging by the large size of the ulna the animal may belong to the sauropod dinosaur, which is much bigger than Supersaurus. A new name Ultrasaurus tabriensis is proposed for the convenience of the further study.” While this does not quite go so far as to say that Kim considered the ulna to belong to the same genus as Jensen’s brachiosaur, it seems unlikely that he was aware of Supersaurus but not of Ultrasaurus, and landed independently on the latter name by coincidence. In fact, the “ulna” is a humerus, as shown by Lee et al. (1997).

Either way, in naming his species, Kim inadvertently preoccupied Jensen’s chosen genus name, with conseqences that we shall see below. By all accounts, the material the Kim described is in any case indeterminate, and the genus is generally considered a nomen nudum (e.g. Olshevsky 1991:139, Glut 1997:1001).

Kim 1983, plate 1, parts 1-3, illustrating the proximal portion of the huge “ulna” that the name Ultrasaurus tabriensis was founded on. As is apparent, this is actually the proximal end of a humerus, meaning that the animal is rather less large than Kim supposed — although the 42 cm width across the proximal end is still nothing to be sniffed at. It is about 71% the width of the 59 cm-wide humerus of the Giraffatitan brancai paralectotype MB.R.2181 (previously HMN SII).

Two years after this, and presumably unaware of Kim’s paper or incorrectly assuming his informal use of the name “Ultrasaurus” gave him priority, Jensen published a formal account of his finds, naming them (Jensen 1985). Unfortunately, while the paper does contain formal nomenclatural acts that are valid according to the rules of the ICZN, Jensen did not explain his reasoning for the creation of the new genera, and his selection of type material was problematic, as we shall see below. Also, the specimen numbers that he used have been superseded — I do not know why, but my guess would be that he re-used numbers that were already in use for other specimens, so his own material had to be given new numbers.

3. Jensen’s three sauropods

The following three genera (with their type species) were named, in this order:

1. Supersaurus vivianae, based on the holotype BYU 9025 (BYU 5500 of his usage), a scapulocoracoid measuring 2.44 m in length. To this, he referred an even larger scapulocoracoid whose length he gives as 2.70 m (though Curtice and Stadtman 2001:39 found that this length to be due to optimistic reconstruction); an ischium; either one or two mid-caudal vertebrae (his paper contradicts itself on this); and a sequence of 12 articulated caudal vertebrae. Unfortunately, Jensen’s use of specimen numbers for most of these referred elements is inconsistent, but he is at least consistent in referring to the second scapulocoracoid as BYU 5501.

Supersaurus vivianae referred scapulocoracoid BYU 12962, photographed at the North American Museum of Natural Life. The exhibit text reads: “Supersaurus scapula and coracoid. This is the actual Supersaurus bone that the world saw when the announcement was made of the new animal’s discovery in 1972. The scapula lay in the ground for five more years, waiting for the collection of other fossils that lay in the path of excavation. The flatness of the bone presented a challenge to “Dinosaur Jim” Jensen, who had to figure out a way to get the bone safely out of the ground. He finally accomplished this by cutting the scapula into three pieces. In 1988, Cliff Miles, Brian Versey and Clark Miles prepared the bone for study. It is still one of the largest dinosaur bones known in the world. Specimen on loan from Brigham Young University’s Earth Science Museum. Late Jurassic/Early Cretaceous (about 144 million years ago)

2. Ultrasaurus macintoshi, based on the holotype BYU 9044 (BYU 5000 of his usage), a dorsal vertebra measuring 1.33 m in height. To this, he referred BYU 9462 (BYU 5001 of his usage), a scapulocoracoid measuring 2.7 m in length; BYU 9024 (BYU 5003 of his usage), a huge cervical vertebra; and an anterior caudal vertebra.

Ultrasaurus macintoshi holotype dorsal vertebra BYU 9044, photographed at the North American Museum of Natural Life. (It’s incredibly hard to photograph well because it’s behind reflective glass.)

3. Dystylosaurus edwini, based on the holotype BYU 4503 (BYU 5750 of his usage), a dorsal vertebra. He did not refer any other material to this taxon, and considered it “Family indeterminate” commenting that it “no doubt represents a new sauropod family”. Poor Dystylosaurus has always been the unloved member of this group, and pretty much ignored in the literature aside from the Curtice & Stadtman (2001) synonymisation paper discussed below.

Dystylosaurus edwini holotype BYU 4503, a diplodocoid anterior dorsal vertebra.

In a subsequent paper, Jensen (1987:600–602) removed the big cervical BYU 9024 (BYU 5003 of his usage) from Ultrasauros and reassigned it to Diplodocidae. The text of this paper never refers it to Supersaurus vivianae in particular, but it is illustrated and captioned as belonging to that taxon (Jensen 1987:figures 7A-B, 8C), and this assignment is generally assumed to have been meant.

When Jensen became aware of Kim’s (1983) preoccupation of the name Ultrasaurus, he recognised that his own genus needed a new name. At his suggestion, Olshevsky (1991) erected the replacement name Ultrasauros (with a single-letter spelling difference) for Jensen’s taxon based on the dorsal vertebra BYU 9044. We will use this revised spelling hereon, and the taxon Ultrasaurus Kim 1983 is of no further interest to this story.

The relevant extract from Olshevsky (1991:139).

4. Curtice’s synonymies

This was how things stood, with Jensen’s assignment of the material to his three new genera standing unchallenged, until Brian Curtice came on the scene in the mid 1990s. In a series of three publications (two papers, one abstract), he first synonymised Ultrasauros with Supersaurus, then Dystylosaurus also with Supersaurus, and finally (tentatively) Supersaurus itself with Barosarus. If Curtice’s suggestions were all correct, then there were no new sauropods from Jensen’s work in the the Dry Mesa quarry, just a lot of Barosaurus material.

Was he right? We’ll now consider each of the three publications in turn.

First, Ultrasauros. Jensen had always considered this genus to be a brachiosaurid due to the morphology of the scapulocoracoid BYU 9462 — and indeed this element does seem to be brachiosaurid. Unfortunately, he did not found the taxon on this element, but on the dorsal vertebra BYU 9044. Curtice et al. (1996) re-examined this element, and argued convincingly that it was not an anterior dorsal from a brachiosaurid, as Jensen had thought, but a posterior dorsal from a diplodocid. Since its neural spine morphology matches that of the first preserved sacral spine (S2) of the Supersaurus sacrum, and since it was found between the two Supersaurus scapulocoracoids, Curtice et al. (1996:94) considered BYU 9044 to be a vertebra of Supersaurus (belonging to the holotype individual), and therefore concluded that Ultrasauros was a junior subjective synonym of Supersaurus. They inferred that the referred Ultrasauros scapulocoracoid BYU 9462 therefore did not belong to the same species as the type, since it was brachiosaurid, and referred it to Brachiosaurus sp.

We consider all of Curtice et al.’s (1996) arguments well-founded and convincing, and agree with their conclusions. As a result, both spellings of Jensen’s brachiosaurid genus are now discarded: Ultrasaurus as a nomen dubium, and Ultrasauros as a junior synonym.

Curtice et al. (1996:figure 2). “Uncrushed” Supersaurus vivianae caudal dorsal, BYU 9044, right lateral view.

A few years later, Curtice and Stadtman (2001) took aim at Dystylosaurus. Jensen had argued that it was unique because of the paired centroprezygapophyseal laminae that supported each prezygapophysis from below — and it was from this feature than the genus took its name. But Curtice and Stadtman pointed out that this supposedly unique feature is in fact almost ubiquitous in diplodocids. Because it, too, was found between the two Supersaurus scapulae (close to the Ultrasaurus dorsal), Curtice and Stadtman referred it, too, to Supersaurus, thereby collapsing all three of Jensen’s taxa into one. This argument, too, is well supported and has been generally accepted.

Finally, in a sole-authored abstract, Curtice (2003) hedged about whether he considered Supersaurus to be Barosaurus. I will quote directly, as the line of reasoning is vague and difficult to summarise:

The question of is Supersaurus truly a distinct genus from Barosaurus is now testable. The former Dystylosaurus dorsal vertebra provides an autapomorphy for Supersaurus, that being a strongly reduced bifid neural spine on dorsal four. This loss of bifidity is important for in all other diplodocids the neural spine is still deeply bifurcated on dorsal four. Only Barosaurus has a reduction in cleft depth that far forward in the dorsal column. Supersaurus has all but lost the cleft, more closely resembling the sixth dorsal vertebra of Barosaurus than the fourth.

It is disappointing that this abstract never became a more rigorously argued paper, because the conclusion here is highly equivocal. Curtice appears to be saying that Supersaurus is distinct from Barosaurus — but only on the basis of bifidity reducing two vertebrae more anteriorly in Supersaurus. In other words, he seems to be suggesting that the two taxa are indisinguishable aside from this rather minor difference.

At any rate, this speculation in a conference abstract has generally been ignored, and Supersaurus considered a valid and distinct genus.

5. Jimbo the WDC Supersaurus

In 2008, Lovelace et al. (2008, duh) described WDC DMJ-021, a new specimen of Supersaurus vivianae at the Wyoming Dinosaur Center that is known informally as “Jimbo”. (Confusingly, they refer to the Supersaurus holotype scapulocoracoid by yet a third specimen number, BYU 12962; but this is the revised specimen number of the referred scapulocoracoid, not the holotype.)

Lovelace et al. (2008) did not justify in detail their referral of Jimbo to Supersaurus. The closest they come is this brief passage on page 529–530:

While a scapula is not known for WDC DMJ-021, other elements are identical to axial elements referred to the type individual of Supersaurus. Referral of all material is supported by relative position within their respective quarries (Curtice and Stadtman 2001; Lovelace 2006), size of the skeletal elements, and congruence of phylogenetically significant diplodocid characters between the scapula and referred material.

All of this is kind of weaselly. What it amounts to is this: vertebrae are “identical” to those referred to the BYU Supersaurus (but not really, as we’ll see), and the elements are really big, and the Supersaurus holoype scap comes out in about the same place as Jimbo in a phylogenetic analysis if you code them up separately. This is weak sauce, and I would really have liked to see a much more explicit “Jimbo shares synapomorphies X, Y and Z with BYU Supersaurus” section.

Among the ways in which the justification for this assignment disappoints is that the presacrals that are described as “identical” to the BYU elements are not at all well preserved (Lovelace et al. 2008:figures 3D–E, 4A, 5A): in particular C13, presumably the best preserved cervicals as it is the only one illustrated, is missing the condyle, prezygapophyses and neural spine. It’s not possible to be sure in light of the small monochrome illustrations in the paper, but it does not seem likely that these elements can be reliably assessed as identical to the BYU cervical.

Lovelace et al. (2008:figure 3). Lateral views of cervical vertebrae from A, Diplodocus carnegii (Hatcher 1901); B, Barosaurus lentus (Lull 1919); C, Apatosaurus louisae (Gilmore 1936); D and E, Supersaurus vivianae; demonstrating pneumatic modifications of centra. Supersaurus has the least amount of modification with minimal size for pneumatopores. Internal structure is similar to that seen in other diplodocids (Janensch, 1947). Left lateral view of Cv.13 (D, missing the condyle, prezygapophyses and neural spine; length of incomplete centra 94cm). E, cross section through Cv.11, 5cm posterior of the diapophysis.

The big surprise in the Jimbo paper is that in the phylogenetic analysis (Lovelace et al. 2008:figure 14), the compound BYU+WDC Supersaurus is recovered as an apatosaurine, the sister taxon to Apatosaurus, rather than as a diplodocine as had been assumed in previous studies due to its resemblance to the diplodocine Barosaurus.

The huge specimen-level phylogenetic analysis of diplodocoids by Tschopp et al. (2015) corroborated Lovelace et al’s (2008) referral of the WDC specimen to Supersaurus vivianae, as the two species were sister groups in all most parsimonious trees, with quite strong character support (Tschopp et al. 2015:187). But it placed the Supersaurus clade at the base of Diplodocinae, not within Apatosaurinae as Lovelace et al. (2008) had found.

This, then, was the state of play when Matt and I started to work on Supersaurus during the 2016 Sauropocalypse: Ultrasauros and Dystylosaurus had both been sunk into Supersaurus, and the WDC specimen had been referred to the same species.

Next time, we’ll look what Matt and I found in Utah, and what we think it means for Supersaurus and its friends.

 

References

  • Curtice, Brian D. 2003. Two genera down, one to go? The potential synonomy [sic] of Supersaurus with Barosaurus. Southwest Paleontological Symposium 2003, Guide to Presentations. Mesa Southwest Museum, January 25 2003. Unpaginated.
  • Curtice, Brian D. and Kenneth L. Stadtman. 2001. The demise of Dystylosaurus edwini and a revision of Supersaurus vivianae. Western Association of Vertebrate Paleontologists and Mesa Southwest Museum and Southwest Paleontologists Symposium, Bulletin 8:33-40.
  • Curtice, Brian D., Kenneth L. Stadtman and Linda J. Curtice. 1996. A reassessment of Ultrasauros macintoshi (Jensen, 1985). M. Morales (ed.), “The continental Jurassic”. Museum of Northern Arizona Bulletin 60:87–95.
  • George, Jean. 1973a. Supersaurus, giant of the giants. Denver Post,
    Empire Magazine. May 13, 1973, pp 14ff.
  • George, Jean. 1973b. Supersaurus, the biggest brute ever. Reader’s Digest (June 1973):51–56.
  • Glut, Donald F. 1997. Dinosaurs: the Encyclopedia. McFarland & Company Inc., Jefferson. 1076 pp.
  • Jensen, James A. 1985. Three new sauropod dinosaurs from the Upper Jurassic of Colorado. Great Basin Naturalist 45(4):697–709.
  • Jensen, James A. 1987. New brachiosaur material from the Late Jurassic of Utah and Colorado. Great Basin Naturalist 47(4):592–608.
  • Kim, Haang Mook. 1983. Cretaceous dinosaurs from South Korea. Journal of the Geological Society of Korea 19(3):115–126.
  • Lee, Yuong-Nam., S. Y. Yang and E. J. Park. 1997. Sauropod dinosaur remains from the Gyeongsang Supergroup, Korea; pp. 103–114 in S. Y. Yang, M. Huh, Y.-N. Lee and M. G. Lockley (eds.), International Dinosaur Symposium for Uhangri Dinosaur Center and Theme Park in Korea. Journal of Paleontological Society of Korea, Special Publication 2.
  • Lovelace, David M., Scott A. Hartman and William R. Wahl. 2008. Morphology of a specimen of Supersaurus (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny. Arquivos do Museu Nacional, Rio de Janeiro 65(4):527–544.
  • Olshevsky, George. 1991. A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings 2:1–196.
  • Tschopp, Emanuel, Octávio Mateus and Roger B. J. Benson. 2015. A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 2:e857. doi:10.7717/peerj.857

 

A bunch of stuff, loosely organized by theme.

Media

First up, I need to thank Brian Switek, who invited me to comment on Patagotitan for his piece at Smithsonian. I think he did a great job on that, arguably the best of any of the first-day major media outlet pieces. And it didn’t go unnoticed – his article was referenced at both the Washington Post and NPR (and possibly other outlets, those are the two I know of right now). I don’t think my quotes got around because they’re particularly eloquent, BTW, but rather because reporters tend to like point-counterpoint, and I was apparently the most visible counterpoint. They probably would have done the same if I’d been talking complete nonsense (which, to be fair, some people may think I was).

Paleobiology vs Records

The most commonly reproduced quote of mine is this one, originally from Brian’s piece:

I think it would be more accurate to say that Argentinosaurus, Puertasaurus and Patagotitan are so similar in size that it is impossible for now to say which one was the largest.

That may seem at odds with the, “Well, actually…[pushes glasses up nose]…Argentinosaurus was still biggest” tack I’ve taken both in my post yesterday and on Facebook. So let me elaborate a little.

There is a minor, boring point, which is that when I gave Brian that quote, I’d seen the Patagotitan paper, but not the Electronic Supplementary Materials (ESM), so I knew that Patagotitan was about the same size as the other two (and had known for a while), but I hadn’t had a chance to actually run the numbers.

The much more interesting point is that the size differences between Argentinosaurus, Puertasaurus, and Patagotitan are astonishingly small. The difference between a 2.5m femur and a 2.4m one is negligible, ditto for vertebrae with centra 59cm and 60cm in diameter. OMNH 1331, the biggest centrum bit from the giant Oklahoma apatosaur, had an intact max diameter of 49cm, making it 26% larger in linear terms than the next-largest apatosaur. The centra of these giant South American titanosaurs are more than 20% bigger yet than OMNH 1331, just in linear terms. That’s crazy.

It’s also crazy that these three in particular – Argentinosaurus, Puertasaurus, and Patagotitan – are so similar in size. Dinosaur developmental programs were ‘messy’ compared to those of mammals, both in having weird timings for things like onset of reproduction, and in varying a lot among closely related taxa. Furthermore, sauropod population dynamics should have been highly skewed toward juveniles and subadults. So is the near-equality in size among Argentinosaurus, Puertasaurus, and Patagotitan just a coincidence, or does it mean that something weird was going on? There’s really no third option. I mean, even if some kind of internal (biomechanical or physiological) or external (ecological, food or predation) constraint forced those three to the same adult body size, it’s weird then that we’re finding only or at least mostly near-max-size adults. (If the available specimens of these three aren’t near-max-size, then any hypothesis that they’re forced to the same size by constraints is out the window, and we’re back to coincidence.)

BUT

With all that said, the title of “world’s largest dinosaur” is not handed out for effort expended, number of specimens collected, skeletal completeness, ontogenetic speculation, or anything other than “the dinosaur with the largest measured elements”. And that is currently Argentinosaurus. So although for any kind of paleobiological consideration we can currently consider Argentinosaurus, Puertasaurus, and Patagotitan to all be about the same size – and Alamosaurus, Paralititan, Notocolossus, and probably others I’ve forgotten should be in this conversation – anyone wanting to dethrone Argentinosaurus needs to actually show up with bigger elements.

So, if you’re interested in paleobiology, it’s fascinating and frankly kind of unnerving that so many of these giant titanosaurs were within a hand-span of each other in terms of size. Patagotitan is one more on the pile – and, as I said yesterday, exciting because it’s so complete.

But if you want to know who holds the crown, it’s still Argentinosaurus.

Humeri

In a comment on the last post, Andrea Cau made an excellent point that I am just going to copy here entire:

Even Paralititan stromeri humerus is apparently larger than Patagotitan humerus (169 cm vs 167.5 cm). I know humerus length alone is bad proxy of body size, but at least this shows that even in that bone Patagotitan is just another big titanosaur among a well known gang of titans, not a supersized one.

That made me want to start a list of the longest sauropod humeri. Here goes – if I missed anyone or put down a figure incorrectly, I’m sure you’ll let me know in the comments.

  • Giraffatitan: 213cm
  • Brachiosaurus: 203cm
  • Ruyangosaurus: 190cm (estimated from 135cm partial)
  • Turiasaurus: 179cm
  • Notocolossus: 176cm
  • Paralititan: 169cm
  • Patagotitan: 167.5cm
  • Dreadnoughtus: 160cm
  • Futlognkosaurus: 156cm

Admittedly the Patagotitan humerus is from a paratype and not from the largest individual, but that is true for some others on the list, including Giraffatitan. And we have no humeri from Argentinosaurus, Puertasaurus, and some other giants.

Dorsal Vertebrae

A couple of further thoughts on how the dorsal vertebrae of Patagotitan compare to those of Argentinosaurus. First, now that I’ve had some time to think about it, I have a hard time seeing how the dorsal polygon method used by Carballido et al. in the Patagotitan paper has any biological meaning. In their example figure, the polygon around the Puertasaurus vertebra is mostly full of bone, and the one around Patagotitan has a lot of empty space. It’s easy to imagine an alternative metric, like “area of the minimum polygon actually filled by bone”, that would lead to a different ‘winner’. But that wouldn’t mean much, either.

Something that probably does have a real and important biomechanical meaning is the surface area of the articular face of the centrum, because that’s the area of bone that has to bear the compressive load, which is directly related to the animal’s mass. The biggest Patagotitan centrum is that of MPEF-PV 3400/5, which is at least a local maximum since has smaller centra both ahead and behind. The posterior face measures 59cm wide by 42.5cm tall. Abstracted as an ellipse, which may not be perfectly accurate, those measurements give a surface area of (pi)(29.5)(21.25)=1970 cm^2. For Argentinosaurus, the largest complete centrum has a posterior face measuring 60cm wide by 47cm tall (Bonaparte and Coria 1993: p. 5), giving an elliptical surface area of (pi)(30)(23.5)=2210 cm^2. (I’d use hi-res images of the centra to measure the actual surface areas if I could, but AFAIK those images either don’t exist or at least have not yet been made public, for either taxon.) So although the Argentinosaurus dorsal seems like it is only a bit bigger in linear terms, it’s 12% larger in surface area, and that might actually be a meaningful difference.

Cervical Vertebrae

One thing I haven’t commented on yet – Patagotitan is the newest member of the “world’s longest vertebrae” club. The longest Patagotitan cervical, MPEF-PV 3400/3, is listed in the ESM as having a centrum length of 120cm, but it’s also listed as incomplete. In the skeletal recon in the paper, the centrum is colored in as present, but the neural spine is missing. So is the centrum complete in terms of length? I don’t think it’s clear right now.

Anyway, here’s the current rundown of the longest cervical centra of sauropods (and therefore, the longest vertebrae among animals):

  • BYU 9024, possibly referable to Supersaurus or Barosaurus: 137cm
  • Price River 2 titanosauriform: 129cm
  • OMNH 53062, Sauroposeidon holotype: 125cm
  • KLR1508-77-2, Ruyangosaurus giganteus referred specimen: 124cm
  • MPEF-PV 3400/3, Patagotitan holotype: 120cm (+?)
  • MPM 10002, Puertasaurus holotype: 118cm

You may be surprised to see the Price River 2 cervical in there. It was reported in an SVP abstract a few years ago (I’ll dig up that ref and update this post), and Mike and I saw it last year on the Sauropocalypse. We measured the centrum at 129cm, making it just a bit longer than the longest centrum of Sauroposeidon, and therefore the second-longest vertebra of anything ever.

Aside – I’m probably getting a reputation as a big ole meanie when it comes to debunking “world’s largest dinosaur” claims. If I’m willing to take the lead in kicking my own dinosaur down the ladder, don’t expect me to be kind to yours. I follow where the numbers lead.

Now, here’s an interesting thing – now that Sauroposeidon is coming out as a basal titanosaur, rather than a brachiosaur, it might not have been a skinny freak. The 120cm cervical of Patagotitan makes the 125cm cervical of Sauroposeidon and the 129cm cervical from Price River 2 look even more tantalizing. Maybe it’s super-giant sauropods all the way down.

Notocolossus is a beast

January 20, 2016

Notocolossus skeletal recon - Gonzalez Riga et al 2016 fig 1

(a) Type locality of Notocolossus (indicated by star) in southern-most Mendoza Province, Argentina. (b) Reconstructed skeleton and body silhouette in right lateral view, with preserved elements of the holotype (UNCUYO-LD 301) in light green and those of the referred specimen (UNCUYO-LD 302) in orange. Scale bar, 1 m. (González Riga et al. 2016: figure 1)

This will be all too short, but I can’t let the publication of a new giant sauropod pass unremarked. Yesterday Bernardo González Riga and colleagues published a nice, detailed paper describing Notocolossus gonzalezparejasi, “Dr. Jorge González Parejas’s southern giant”, a new titanosaur from the Late Cretaceous of Mendoza Province, Argentina (González Riga et al. 2016). The paper is open access and freely available to the world.

As you can see from the skeletal recon, there’s not a ton of material known from Notocolossus, but among giant sauropods it’s actually not bad, being better represented than Argentinosaurus, Puertasaurus, Argyrosaurus, and Paralititan. In particular, one hindfoot is complete and articulated, and a good chunk of the paper and supplementary info are devoted to describing how weird it is.

But let’s not kid ourselves – you’re not here for feet, unless it’s to ask how many feet long this monster was. So how big was Notocolossus, really?

Well, it wasn’t the world’s largest sauropod. And to their credit, no-one on the team that described it has made any such superlative claims for the animal. Instead they describe it as, “one of the largest terrestrial vertebrates ever discovered”, and that’s perfectly accurate.

Notocolossus limb bones - Gonzalez Riga et al 2016 fig 4

(a) Right humerus of the holotype (UNCUYO-LD 301) in anterior view. Proximal end of the left pubis of the holotype (UNCUYO-LD 301) in lateral (b) and proximal (c) views. Right tarsus and pes of the referred specimen (UNCUYO-LD 302) in (d) proximal (articulated, metatarsus only, dorsal [=anterior] to top), (e) dorsomedial (articulated), and (f) dorsal (disarticulated) views. Abbreviations: I–V, metatarsal/digit number; 1–2, phalanx number; ast, astragalus; cbf, coracobrachialis fossa; dpc, deltopectoral crest; hh, humeral head; ilped, iliac peduncle; of, obturator foramen; plp, proximolateral process; pmp, proximomedial process; rac, radial condyle; ulc, ulnar condyle. Scale bars, 20 cm (a–c), 10 cm (d–f). (Gonzalez Riga et al 2016: figure 4)

Any discussions of the size of Notocolossus will be driven by one of two elements: the humerus and the anterior dorsal vertebra. The humerus is 176 cm long, which is shorter than those of Giraffatitan (213 cm), Brachiosaurus (204 cm), and Turiasaurus (179 cm), but longer than those of Paralititan (169 cm), Dreadnoughtus (160 cm), and Futalognkosaurus (156 cm). Of course we don’t have a humerus for Argentinosaurus or Puertasaurus, but based on the 250-cm femur of Argentinosaurus, the humerus was probably somewhere around 200 cm. Hold that thought.

Notocolossus and Puertasaurus dorsals compared

Top row: my attempt at a symmetrical Notocolossus dorsal, made by mirroring the left half of the fossil from the next row down. Second row: photos of the Notocolossus dorsal with missing bits outlined, from Gonzalez Riga et al (2016: fig. 2). Scale bar is 20 cm (in original). Third row: the only known dorsal vertebra of Puertasaurus, scaled to about the same size as the Notocolossus vertebra, from Novas et al. (2005: fig. 2).

The anterior dorsal tells a similar story, and this is where I have to give González Riga et al. some props for publishing such detailed sets of measurements in the their supplementary information. They Measured Their Damned Dinosaur. The dorsal has a preserved height of 75 cm – it’s missing the tip of the neural spine and would have been a few cm taller in life – and by measuring the one complete transverse process and doubling it, the authors estimate that when complete it would have been 150 cm wide. That is 59 inches, almost 5 feet. The only wider vertebra I know of is the anterior dorsal of Puertasaurus, at a staggering 168 cm wide (Novas et al. 2005). The Puertasaurus dorsal is also quite a bit taller dorsoventrally, at 106 cm, and it has a considerably larger centrum: 43 x 60 cm, compared to 34 x 43.5 cm for Notocolossus (anterior centrum diameters, height x width).

Centrum size is an interesting parameter. Because centra are so rarely circular, arguably the best way to compare across taxa would be to measure the max area (or, since centrum ends are also rarely flat, the max cross-sectional area). It’s late and this post is already too long, so I’m not going to do that now. But I have been keeping an informal list of the largest centrum diameters among sauropods – and, therefore, among all Terran life – and here they are (please let me know if I missed anyone):

  • 60 cm – Argentinosaurus dorsal, MCF-PVPH-1, Bonaparte and Coria (1993)
  • 60 cm – Puertasaurus dorsal, MPM 10002, Novas et al. (2005)
  • 51 cm – Ruyangosaurus cervical and dorsal, 41HIII-0002, Lu et al. (2009)
  • 50 cm – Alamosaurus cervical, SMP VP−1850, Fowler and Sullivan (2011)
  • 49 cm – Apatosaurus ?caudal, OMNH 1331 (pers. obs.)
  • 49 cm – Supersaurus dorsal, BYU uncatalogued (pers. obs.)
  • 46 cm – Dreadnoughtus dorsal, MPM-PV 1156, Lacovara et al. (2014: Supplmentary Table 1) – thanks to Shahen for catching this one in the comments!
  • 45.6 cm – Giraffatitan presacral, Fund no 8, Janensch (1950: p. 39)
  • 45 cm – Futalognkosaurus sacral, MUCPv-323, Calvo et al. (2007)
  • 43.5 cm – Notocolossus dorsal, UNCUYO-LD 301, González Riga et al. (2016)

(Fine print: I’m only logging each taxon once, by its largest vertebra, and I’m not counting the dorsoventrally squashed Giraffatitan cervicals which get up to 47 cm wide, and the “uncatalogued” Supersaurus dorsal is one I saw back in 2005 – it almost certainly has been catalogued in the interim.) Two things impress me about this list: first, it’s not all ‘exotic’ weirdos – look at the giant Oklahoma Apatosaurus hanging out halfway down the list. Second, Argentinosaurus and Puertasaurus pretty much destroy everyone else by a wide margin. Notocolossus doesn’t seem so impressive in this list, but it’s worth remembering that the “max” centrum diameter here is from one vertebra, which was likely not the largest in the series – then again, the same is true for Puertasaurus, Alamosaurus, and many others.

Notocolossus phylogeny - Gonzalez Riga et al 2016 fig 5

(a) Time-calibrated hypothesis of phylogenetic relationships of Notocolossus with relevant clades labelled. Depicted topology is that of the single most parsimonious tree of 720 steps in length (Consistency Index = 0.52; Retention Index = 0.65). Stratigraphic ranges (indicated by coloured bars) for most taxa follow Lacovara et al.4: fig. 3 and references therein. Additional age sources are as follows: Apatosaurus[55], Cedarosaurus[58], Diamantinasaurus[59], Diplodocus[35], Europasaurus[35], Ligabuesaurus[35], Neuquensaurus[60], Omeisaurus[55], Saltasaurus[60], Shunosaurus[55], Trigonosaurus[35], Venenosaurus[58], Wintonotitan[59]. Stratigraphic ranges are colour-coded to also indicate geographic provenance of each taxon: Africa (excluding Madagascar), light blue; Asia (excluding India), red; Australia, purple; Europe, light green; India, dark green; Madagascar, dark blue; North America, yellow; South America, orange. (b–h) Drawings of articulated or closely associated sauropod right pedes in dorsal (=anterior) view, with respective pedal phalangeal formulae and total number of phalanges per pes provided (the latter in parentheses). (b) Shunosaurus (ZDM T5402, reversed and redrawn from Zhang[45]); (c) Apatosaurus (CM 89); (d) Camarasaurus (USNM 13786); (e) Cedarosaurus (FMNH PR 977, reversed from D’Emic[32]); (f) Epachthosaurus (UNPSJB-PV 920, redrawn and modified from Martínez et al.[22]); (g) Notocolossus; (h) Opisthocoelicaudia (ZPAL MgD-I-48). Note near-progressive decrease in total number of pedal phalanges and trend toward phalangeal reduction on pedal digits II–V throughout sauropod evolutionary history (culminating in phalangeal formula of 2-2-2-1-0 [seven total phalanges per pes] in the latest Cretaceous derived titanosaur Opisthocoelicaudia). Abbreviation: Mya, million years ago. Institutional abbreviations see Supplementary Information. (González Riga et al. 2016: figure 5)

As for the estimated mass of Notocolossus, González Riga et al. (2016) did their due diligence. The sections on mass estimation in the main text and supplementary information are very well done – lucid, modest, and fair. Rather than try to summarize the good bit, I’ll just quote it. Here you go, from page 7 of the main text:

The [humeral] diaphysis is elliptical in cross-section, with its long axis oriented mediolaterally, and measures 770 mm in minimum circumference. Based on that figure, the consistent relationship between humeral and femoral shaft circumference in associated titanosaurian skeletons that preserve both of these dimensions permits an estimate of the circumference of the missing femur of UNCUYO-LD 301 at 936 mm (see Supplementary Information). (Note, however, that the dataset that is the source of this estimate does not include many gigantic titanosaurs, such as Argentinosaurus[5], Paralititan[16], and Puertasaurus[11], since no specimens that preserve an associated humerus and femur are known for these taxa.) In turn, using a scaling equation proposed by Campione and Evans[20], the combined circumferences of the Notocolossus stylopodial elements generate a mean estimated body mass of ~60.4 metric tons, which exceeds the ~59.3 and ~38.1 metric ton masses estimated for the giant titanosaurs Dreadnoughtus and Futalognkosaurus, respectively, using the same equation (see Supplementary Information). It is important to note, however, that subtracting the mean percent prediction error of this equation (25.6% of calculated mass[20]) yields a substantially lower estimate of ~44.9 metric tons for UNCUYO-LD 301. Furthermore, Bates et al.[21] recently used a volumetric method to propose a revised maximum mass of ~38.2 metric tons for Dreadnoughtus, which suggests that the Campione and Evans[20] equation may substantially overestimate the masses of large sauropods, particularly giant titanosaurs. Unfortunately, however, the incompleteness of the Notocolossus specimens prohibits the construction of a well-supported volumetric model of this taxon, and therefore precludes the application of the Bates et al.[21] method. The discrepancies in mass estimation produced by the Campione and Evans[20] and Bates et al.[21] methods indicate a need to compare the predictions of these methods across a broad range of terrestrial tetrapod taxa[21]. Nevertheless, even if the body mass of the Notocolossus holotype was closer to 40 than 60 metric tons, this, coupled with the linear dimensions of its skeletal elements, would still suggest that it represents one of the largest land animals yet discovered.

So, nice work all around. As always, I hope we get more of this critter someday, but until then, González Riga et al. (2016) have done a bang-up job describing the specimens they have. Both the paper and the supplementary information will reward a thorough read-through, and they’re free, so go have fun.

References

The paper

Open access (CC By) at PLOS ONE:

  • Upchurch, Paul, Philip D. Mannion and Micahel P Taylor. 2015. The Anatomy and Phylogenetic Relationships of “Pelorosaurus” becklesii (Neosauropoda, Macronaria) from the Early Cretaceous of England. PLoS ONE 10(6):e0125819. doi:10.1371/journal.pone.0125819 [PDF]

SV-POW! posts

High-resolution figures

Fig 1. Map showing England and Wales, with boundaries for English counties. The magnified inset shows the Isle of Wight and East and West Sussex in more detail, marking the positions of selected major towns/cities and the fossil localities mentioned in the main text. Based on

Fig 1. Map showing England and Wales, with boundaries for English counties.
The magnified inset shows the Isle of Wight and East and West Sussex in more detail, marking the positions of selected major towns/cities and the fossil localities mentioned in the main text. Based on “English ceremonial counties 1998” by Dr. Greg (see the Wikipedia website at http://en.wikipedia.org/wiki/File:Englis​h_ceremonial_counties_1998.svg.: accessed 1st August 2014): CC By-SA 3.0.

Fig 2. Left humerus of Haestasaurus becklesii (NHMUK R1870). A, anterior view; B, posterior view; Abbreviations: af, anconeal fossa; dp, deltopectoral crest; hh, humeral head; ltf, lateral triceps fossa; mtf, medial triceps fossa.

Fig 2. Left humerus of Haestasaurus becklesii (NHMUK R1870).
A, anterior view; B, posterior view; Abbreviations: af, anconeal fossa; dp, deltopectoral crest; hh, humeral head; ltf, lateral triceps fossa; mtf, medial triceps fossa.

Fig 3. Left humerus of Haestasaurus becklesii (NHMUK R1870). A, lateral view; B, medial view; C, proximal end view (posterior surface towards top); D, distal end view (anterior surface towards top). Abbreviations: aep, anterior entepicondylar process; af, anconeal fossa; alf, anterolateral fossa; dp, deltopectoral crest; hh, humeral head; lad, lateral anterodistal process; mad, medial anterodistal process. All parts are at the same scale.

Fig 3. Left humerus of Haestasaurus becklesii (NHMUK R1870).
A, lateral view; B, medial view; C, proximal end view (posterior surface towards top); D, distal end view (anterior surface towards top). Abbreviations: aep, anterior entepicondylar process; af, anconeal fossa; alf, anterolateral fossa; dp, deltopectoral crest; hh, humeral head; lad, lateral anterodistal process; mad, medial anterodistal process. All parts are at the same scale.

Fig 4. Exemplar profiles of the distal ends of sauropod left humeri (anterior surfaces towards top). A, Mamenchisaurus youngi (ZDM 0083 [107]); B, Ferganasaurus (PIN 3042/1 [101]): C, Apatosaurus excelsus (YPM 1980 [100]); D, Camarasaurus grandis (YPM 1901 [100]); E, Haestasaurus (NHMUK R1870); F, Giraffatitan (MfN MB.R 2181 [87]: a right humerus that has been reversed to facilitate comparison); G, Epachthosaurus (UNPSJB-PV 920, based on a photograph by PDM); H, Diamantinasaurus (AAOD 603 [80]); I, Neuquensaurus (MLP-CS 1050 [90]). Abbreviation: aep, anterior entepicondylar process. Profiles not drawn to the same scale.

Fig 4. Exemplar profiles of the distal ends of sauropod left humeri (anterior surfaces towards top).
A, Mamenchisaurus youngi (ZDM 0083 [107]); B, Ferganasaurus (PIN 3042/1 [101]): C, Apatosaurus excelsus (YPM 1980 [100]); D, Camarasaurus grandis (YPM 1901 [100]); E, Haestasaurus (NHMUK R1870); F, Giraffatitan (MfN MB.R 2181 [87]: a right humerus that has been reversed to facilitate comparison); G, Epachthosaurus (UNPSJB-PV 920, based on a photograph by PDM); H, Diamantinasaurus (AAOD 603 [80]); I, Neuquensaurus (MLP-CS 1050 [90]). Abbreviation: aep, anterior entepicondylar process. Profiles not drawn to the same scale.

Fig 5. Left ulna of Haestasaurus becklesii (NHMUK R1870). A, anterolateral view (with anteromedial process directed mainly medially); B, posterior view (with posterior process directed towards the observer). Abbreviations: ampc, concave surface of the anteromedial process; olc, olecranon.

Fig 5. Left ulna of Haestasaurus becklesii (NHMUK R1870).
A, anterolateral view (with anteromedial process directed mainly medially); B, posterior view (with posterior process directed towards the observer). Abbreviations: ampc, concave surface of the anteromedial process; olc, olecranon.

Fig 6. Left ulna of Haestasaurus becklesii (NHMUK R1870). A, lateral view; B, anteromedial view; C, proximal view; D, distal view (N.B. the anteromedial process of the proximal end is visible in this view). Abbreviations: adp, anterior distal process; alp, anterolateral process of the proximal end; amdf, anteromedially facing fossa immediately above the distal end; amp, anteromedial process of the proximal end; raf, fossa for reception of the proximal end of the radius. All parts are at the same scale.

Fig 6. Left ulna of Haestasaurus becklesii (NHMUK R1870).
A, lateral view; B, anteromedial view; C, proximal view; D, distal view (N.B. the anteromedial process of the proximal end is visible in this view). Abbreviations: adp, anterior distal process; alp, anterolateral process of the proximal end; amdf, anteromedially facing fossa immediately above the distal end; amp, anteromedial process of the proximal end; raf, fossa for reception of the proximal end of the radius. All parts are at the same scale.

Fig 7. Left radius of Haestasaurus becklesii (NHMUK R1870). A, anterior view; B, posterior view. Abbreviation: rmi, ridge for muscle insertion (for the tendon from the combined M. biceps and M. brachialis inferior).

Fig 7. Left radius of Haestasaurus becklesii (NHMUK R1870).
A, anterior view; B, posterior view. Abbreviation: rmi, ridge for muscle insertion (for the tendon from the combined M. biceps and M. brachialis inferior).

Fig 8. Left radius of Haestasaurus becklesii (NHMUK R1870). A, lateral view; B, medial view; C, proximal end view (anterior margin towards top); D, distal end view (anterior margin towards top). Abbreviations: antf, anterior fossa; pldc, posterolateral distal condyle; pmdc, posteromedial distal condyle. A and B are at the same scale; C and D are at the same scale.

Fig 8. Left radius of Haestasaurus becklesii (NHMUK R1870).
A, lateral view; B, medial view; C, proximal end view (anterior margin towards top); D, distal end view (anterior margin towards top). Abbreviations: antf, anterior fossa; pldc, posterolateral distal condyle; pmdc, posteromedial distal condyle. A and B are at the same scale; C and D are at the same scale.

Fig 9. Comparisons of sauropod proximal and distal radii. Exemplar profiles of the proximal (A-H) and distal (I-P) ends of sauropod left radii (anterior surfaces towards top): A, I, Ferganasaurus (PIN 3042/1 [101]): B, J, Apatosaurus excelsus (YPM 1980 [100]); C, K, Camarasaurus grandis (YPM 1901 [100]); D, L, Haestasaurus (NHMUK R1870); E, M, Giraffatitan (MfN MB.R 2181 [87]); F, N, Epachthosaurus (UNPSJB-PV 920, based on photographs by PDM); G, O, Diamantinasaurus (AAOD 603 [80]); H, P, Neuquensaurus (MLP-CS 1169 [90]; P based on a photograph provided y S. Poropat). B, E-H, J, and M-P are based on right radii that have been reversed in order to facilitate comparison. Abbreviations: pldc, posterolateral distal condyle; pmdc, posteromedial distal condyle; pmp, proximal medial process. Profiles not drawn to the same scale.

Fig 9. Comparisons of sauropod proximal and distal radii.
Exemplar profiles of the proximal (A-H) and distal (I-P) ends of sauropod left radii (anterior surfaces towards top): A, I, Ferganasaurus (PIN 3042/1 [101]): B, J, Apatosaurus excelsus (YPM 1980 [100]); C, K, Camarasaurus grandis (YPM 1901 [100]); D, L, Haestasaurus (NHMUK R1870); E, M, Giraffatitan (MfN MB.R 2181 [87]); F, N, Epachthosaurus (UNPSJB-PV 920, based on photographs by PDM); G, O, Diamantinasaurus (AAOD 603 [80]); H, P, Neuquensaurus (MLP-CS 1169 [90]; P based on a photograph provided y S. Poropat). B, E-H, J, and M-P are based on right radii that have been reversed in order to facilitate comparison. Abbreviations: pldc, posterolateral distal condyle; pmdc, posteromedial distal condyle; pmp, proximal medial process. Profiles not drawn to the same scale.

Fig 10. Comparisons of sauropod radii in anterior view. Exemplar profiles of sauropod left radii in anterior view: A, Mamenchisaurus youngi (ZDM 0083 [107]); B, Ferganasaurus (PIN 3042/1 [101]); C, Apatosaurus louisae (CM 3018 [104]); D, Camarasaurus grandis (YPM 1901 [100]); E, Haestasaurus (NHMUK R1870); F, Giraffatitan (MfN MB.R 2181 [87]); G, Epachthosaurus (UNPSJB-PV 920, based on a photograph by PDM); H, Diamantinasaurus (AAOD 603 [80]); I, Neuquensaurus (MLP-CS 1169 [90]). The red lines are drawn parallel to the vertical long-axis of each radial shaft, at a tangent to the lateral tip of the distal end. F-I are right radii that have been reversed in order to facilitate comparison. Profiles not drawn to the same scale.

Fig 10. Comparisons of sauropod radii in anterior view.
Exemplar profiles of sauropod left radii in anterior view: A, Mamenchisaurus youngi (ZDM 0083 [107]); B, Ferganasaurus (PIN 3042/1 [101]); C, Apatosaurus louisae (CM 3018 [104]); D, Camarasaurus grandis (YPM 1901 [100]); E, Haestasaurus (NHMUK R1870); F, Giraffatitan (MfN MB.R 2181 [87]); G, Epachthosaurus (UNPSJB-PV 920, based on a photograph by PDM); H, Diamantinasaurus (AAOD 603 [80]); I, Neuquensaurus (MLP-CS 1169 [90]). The red lines are drawn parallel to the vertical long-axis of each radial shaft, at a tangent to the lateral tip of the distal end. F-I are right radii that have been reversed in order to facilitate comparison. Profiles not drawn to the same scale.

Fig 11. The skin impression of Haestasaurus becklesii (NHMUK R1868).

Fig 11. The skin impression of Haestasaurus becklesii (NHMUK R1868).

Fig 12. Definition of anconeal fossa depth ratio. The distal end of the humerus of Camarasaurus grandis (YPM 1901, modified from Ostrom and McIntosh [100]), showing the definition of the ratio used to estimate anconeal (= supracondylar) fossa depth. Ratio = Y/X (see Table 2). Note that X excludes the anterodistal processes if present: this is because these processes are often absent or highly reduced in titanosaurs, and their inclusion in X would mean that the fossa depth ratio would be estimated in an inconsistent manner across Sauropoda. Abbreviation: af, anconeal fossa.

Fig 12. Definition of anconeal fossa depth ratio.
The distal end of the humerus of Camarasaurus grandis (YPM 1901, modified from Ostrom and McIntosh [100]), showing the definition of the ratio used to estimate anconeal (= supracondylar) fossa depth. Ratio = Y/X (see Table 2). Note that X excludes the anterodistal processes if present: this is because these processes are often absent or highly reduced in titanosaurs, and their inclusion in X would mean that the fossa depth ratio would be estimated in an inconsistent manner across Sauropoda. Abbreviation: af, anconeal fossa.

Fig 13. Sauropod ulnae in proximal end view. A, left ulna of Haestasaurus becklesii (NHMUK R1870); B, right ulna (reversed so that it looks like a left) of Diamantinasaurus matildae (AAOD 603 [from 80]). Abbreviations: alp, anterolateral process; amp, anteromedial process; pp, posterior process; raf, fossa for reception of the proximal end of the radius. The blue lines in A mark the long-axes of the anteromedial and anterolateral processes; X, Y and Z mark the tip of the anteromedial process, the tip of the anterolateral process and the intersection of the process long-axes respectively. The anteromedial:anterolateral process length ratio (‘Uppl’ in Table 2) can thus be defined as X-Z/Y-Z.

Fig 13. Sauropod ulnae in proximal end view.
A, left ulna of Haestasaurus becklesii (NHMUK R1870); B, right ulna (reversed so that it looks like a left) of Diamantinasaurus matildae (AAOD 603 [from 80]). Abbreviations: alp, anterolateral process; amp, anteromedial process; pp, posterior process; raf, fossa for reception of the proximal end of the radius. The blue lines in A mark the long-axes of the anteromedial and anterolateral processes; X, Y and Z mark the tip of the anteromedial process, the tip of the anterolateral process and the intersection of the process long-axes respectively. The anteromedial:anterolateral process length ratio (‘Uppl’ in Table 2) can thus be defined as X-Z/Y-Z.

Fig 14. Sauropod ulnae in distal end view (anterior towards bottom). A, left ulna of Haestasaurus becklesii (NHMUK R1870); B, right ulna (reversed so that it looks like a left) of Diamantinasaurus matildae (AAOD 603 [photograph courtesy of S. Poropat). Abbreviations: adp, anterior distal process; amdf, anteromedially facing fossa immediately above the distal end.

Fig 14. Sauropod ulnae in distal end view (anterior towards bottom).
A, left ulna of Haestasaurus becklesii (NHMUK R1870); B, right ulna (reversed so that it looks like a left) of Diamantinasaurus matildae (AAOD 603 [photograph courtesy of S. Poropat). Abbreviations: adp, anterior distal process; amdf, anteromedially facing fossa immediately above the distal end.

Fig 15. Strict consensus tree (CSM). A strict consensus tree based on the 28 most parsimonious trees generated by analysis of the Carballido and Sander [19] data matrix with the addition of Haestasaurus and six new characters (Tendaguria excluded a priori). GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. The monophyletic Diplodocoidea has been collapsed to a single branch in order to reduce figure size. Abbreviation: Brc, Brachiosauridae. See main text for details.

Fig 15. Strict consensus tree (CSM).
A strict consensus tree based on the 28 most parsimonious trees generated by analysis of the Carballido and Sander [19] data matrix with the addition of Haestasaurus and six new characters (Tendaguria excluded a priori). GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. The monophyletic Diplodocoidea has been collapsed to a single branch in order to reduce figure size. Abbreviation: Brc, Brachiosauridae. See main text for details.

Fig 16. Strict consensus tree (LSDM). A strict consensus tree based on the 1778 most parsimonious trees generated by analysis of the Mannion et al. [18] LSDM with the revised scores for Haestasaurus and the addition of six new characters. GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. Abbreviation: Dd, Diplodocoidea. See main text for details.

Fig 16. Strict consensus tree (LSDM).
A strict consensus tree based on the 1778 most parsimonious trees generated by analysis of the Mannion et al. [18] LSDM with the revised scores for Haestasaurus and the addition of six new characters. GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. Abbreviation: Dd, Diplodocoidea. See main text for details.

Fig 17. Strict consensus tree (LCDM). A strict consensus tree based on the 17 most parsimonious trees generated by analysis of the Mannion et al. [18] LCDM with the revised scores for Haestasaurus and the addition of six new characters. GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. Abbreviations: Brc, Brachiosauridae; Dd, Diplodocoidea. N.B. the tree topology shown here means that the clades defined by Brachiosaurus+Saltasaurus (Titanosauriformes) and Andesaurus+Saltasaurus (Titanosauria) are identical. See main text for details.

Fig 17. Strict consensus tree (LCDM).
A strict consensus tree based on the 17 most parsimonious trees generated by analysis of the Mannion et al. [18] LCDM with the revised scores for Haestasaurus and the addition of six new characters. GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. Abbreviations: Brc, Brachiosauridae; Dd, Diplodocoidea. N.B. the tree topology shown here means that the clades defined by Brachiosaurus+Saltasaurus (Titanosauriformes) and Andesaurus+Saltasaurus (Titanosauria) are identical. See main text for details.

Fig 18. Right humerus of Pelorosaurus conybeari (NHMUK 28626). A, lateral; B, anterior; C, medial; D, proximal; E, distal views. Missing portions have been reconstructed using the humerus of Giraffatitan as a guide.

Fig 18. Right humerus of Pelorosaurus conybeari (NHMUK 28626).
A, lateral; B, anterior; C, medial; D, proximal; E, distal views. Missing portions have been reconstructed using the humerus of Giraffatitan as a guide.

A while back, Ben Miller reminded me that when I posted about the old Yale “Brontosaurus” skull, I promised:

So how did the YPM come to make such a monstrosity? What was it based on? Tune in next time for the surprising details!

I told him at the time that I’d soon get around to writing a post. But before I did, he wrote a post on this himself: Bully for Camarasaurus. And it’s excellent. Go and read it!

I don’t have a lot to add to what Ben has written, except regarding this:

What Marsh had instead [when restoring the skull for his 1891 “Brontosaurus” reconstruction] were a few fragmentary bits of Camarasaurus cranial material, plus a snout and jaw (USNM 5730) now considered to be Brachiosaurus.

Here’s what Marsh came up with:

Marsh1891-plateXVI-Apatosaurus-skull-UNREVERSED

But what of the supposed Brachiosaurus skull that he used as a reference? It was finally described 107 years later by Carpenter and Tidwell (1998), in a paper that helpfully also lays out the history behind it. Here’s how it looks:

CarpenterTidwell1998-fig1

The skull was found by a crew under the supervision of M. P. Felch in the western part of his Quarry 1, Garden Park, Colorado. Felch reported it to O. C. Marsh in a letter of 8 September 1883. It was found by a meter-long cervical vertebra that probably belonged to Brachiosaurus “which was destroyed during attempts to collect it” (McIntosh and Berman 1975:196). [Of course, Felch and Marsh could hardly have been expected to identify this vertebra correctly, as Brachiosaurus would not be discovered and named for another twenty years (Riggs 1903), and the nature of its neck would not become apparent until Janensch (1914) described the related brachiosaurid Giraffatitan (= “Brachiosaurus“) brancai.]

The Felch skull, along with other material from the quarry, was shipped to Marsh at Yale in October of that year, and was initially assigned the specimen number YPM 1986. At that time it was only partially prepared, hence the rather poor resemblance between the restored version above and Marsh’s hypothetical “Brontosaurus” [= Apatosaurus] skull that was based on it.

It’s notable that Holland (1915) was quite certain that this was not a skull of Brontosaurus, and that a Diplodocus-like skull found with the A. louisae holotype belonged to it. It’s worth reading the skull section of his paper to see just how solid his reasoning was. And it’s extraordinary to think that Osborn’s power, all the way over in New York, was so great that he was able to successfully bully Holland, 370 miles away in Pittsburgh, into not putting the evidently correct skull on the Carnegie Museum’s Apatosaurus mount. That mount remained sadly headless until after Holland’s death.

Aaanyway, YPM 1986 was pretty much ignored after Marsh’s abuse of it as a reference for the Brontosaurus reconstruction’s skull. After Marsh’s death in 1899, much of the material collected by Felch was transferred to the Smithsonian (US National Museum of Natural History). The skull was among these specimens, and so was re-catalogued as USNM 5730.

As so often, it was Jack McIntosh who rediscovered this skull and recognised its true affinities. Some time after his tentative identification of the skull as pertaining to Brachiosaurus (presumably on the basis of its resemblance to that of Giraffatitan), Carpenter borrowed the skull, had it more fully prepared, wrote the description, and had a restored model constructed from casts of the preserved elements and models of the missing ones.

Carpenter and Tidwell (1998:fig. 2) also handily showed the restored Felch quarry skull alongside those of other sauropods:

CarpenterTidwell1998-fig2

By re-ordering the top row, we can see what a neat intermediate it is between the skulls of Camarasaurus (left) and Giraffatitan (= “Brachiosaurus” of their usage):

CarpenterTidwell1998-fig2-top-row-reordered

I provisionally accepted USNM 5730 as belonging to Brachiosaurus in my re-evaluation of 2009, and included it in my reconstruction (Taylor 2009:fig. 7):

Taylor (2007: figure 7). Skeletal reconstruction of Brachiosaurus altithorax. White bones represent the elements of the holotype FMNH P 25107. Light grey bones represent material referred to B. altithorax: the Felch Quarry skull USNM 5730, the cervical vertebrae BYU 12866 (C?5) and BYU 12867 (C?10), the "Ultrasauros" scapulocoracoid BYU 9462, the Potter Creek left humerus USNM 21903, left radius and right metacarpal III BYU 4744, and the left metacarpal II OMNH 01138. Dark grey bones modified from Paul's (1988) reconstruction of Giraffatitan brancai. Scale bar equals 2 m.

Taylor (2007: figure 7). Skeletal reconstruction of Brachiosaurus altithorax. White bones represent the elements of the holotype FMNH P 25107. Light grey bones represent material referred to B. altithorax: the Felch Quarry skull USNM 5730, the cervical vertebrae BYU 12866 (C?5) and BYU 12867 (C?10), the “Ultrasauros” scapulocoracoid BYU 9462, the Potter Creek left humerus USNM 21903, left radius and right metacarpal III BYU 4744, and the left metacarpal II OMNH 01138. Dark grey bones modified from Paul’s (1988) reconstruction of Giraffatitan brancai. Scale bar equals 2 m.

But as noted by Carpenter and Tidwell (1998:82), the lack of comparable parts between the Felch skull and the Brachiosaurus holotype (which remains the only definitive Brachiosaurus material) means that the assignment has to remain tentative.

What we really need is a more complete Brachiosaurus specimen: one with both a skull and good postcervical elements that let us refer it definitively to Brachiosaurus altithorax by comparison with the holotype. And heck, while we’re at it, let’s have a specimen with a good neck, too!

The real question remains: how did Marsh, using a brachiosaur skull as his basis, come up with this?

Marsh1891-plateXVI-Apatosaurus-skull-UNREVERSED

 

And stranger still, how someone at the Yale Peabody Museum — we don’t know who — used it, or more likely Marsh’s reconstruction, as a basis for this sculpture:

IMG_0517

 

The Yale mount didn’t go up until 1931 — the last of the Big Four Apatosaurus mounts after the AMNH, Carnegie and Field Museum, which is surprising as it was the first of those specimens to be found. So by the time the skull was sculpted, sauropod skulls were actually reasonably well known. It’s not clear quite how anyone working from a decent reconstruction of, say, a Camarasaurus skull — the one in Osborn and Mook (1921:figure 30), say — could come up with this monster.

The last thing to say is this: it does credit to the YPM that they display this historically important sculpture rather than hiding it away and pretending it never happened. For me, part of the fascination of palaeontology is seeing not just how organisms evolved through prehistory but how ideas evolved through history. It’s great that we can still see important mistakes, alongside their corrections (i.e. the new and lovely skull on the YPM Apatosaurus mount.)

 

References

  • Carpenter, Kenneth, and Virginia Tidwell. 1998. Preliminary description of a Brachiosaurus skull from Felch Quarry 1, Garden Park, Colorado. Modern Geology 23:69-84.
  • Holland, William J. 1915. Heads and tails: a few notes relating to the structure of the sauropod dinosaurs. Annals of the Carnegie Museum 9:273-278.
  • Janensch, Werner. 1914. Ubersicht uber der Wirbeltierfauna der Tendaguru-Schichten nebst einer kurzen Charakterisierung der neu aufgefuhrten Arten von Sauropoden. Archiv fur Biontologie, Berlin III, 1(1):81-110.
  • Marsh, O. C. 1891. Restoration of Triceratops (with plates XV and XVI). American Journal of Science, 3rd series 41(244):339-342.
  • McIntosh, John S., and David, S. Berman. 1975. Description of the palate and lower jaw of the sauropod dinosaur Diplodocus (Reptilia: Saurischia) with remarks on the nature of the skull of Apatosaurus. Journal of Paleontology 49(1):187-199.
  • Osborn, Henry Fairfield, and Charles C. Mook. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3:247-387, and plates LX-LXXXV.
  • Riggs, Elmer S. 1903. Brachiosaurus altithorax, the largest known dinosaur. American Journal of Science 15(4):299-306.
  • Taylor, Michael P. 2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of Vertebrate Paleontology 29(3):787-806.

 

How massive was Dreadnoughtus?

September 11, 2014

Dreadnoughtus published body outline - Lacovara et al 2014 fig 2

In the paper describing the new giant titanosaur Dreadnoughtus, Lacovara et al. (2014) use the limb bone allometry equation of Campione and Evans (2012) to derive a mass estimate for the holotype individual of 59.3 metric tons. This is presumably the “middle of the road” value spat out by the equation; the 95% confidence interval on either side probably goes from 40 to 80 metric tons or maybe even wider.

I decided to see if 59 metric tons was plausible for Dreadnoughtus by doing Graphic Double Integration (GDI) on the published skeletal reconstruction and body outline (Lacovara et al. 2014: fig. 2). The image above is the one I used, so if you like, you can check my numbers or try your hand at GDI and see what you get.

First up, I have to congratulate Lacovara et al. for the rare feat of having everything pretty much to scale, and a properly-sized scale bar. This is not always the case. Presumably having a 3D digital model of the reconstructed skeleton helped — and BTW, if you haven’t downloaded the 3D PDFs and played with them, you are missing out bigtime.

Here are my measurements of various bits in the picture and the scale factors they give:

Meter scale bar: 37 pixels – 1.0 meters – 37 px/m
Human figure: 66 pixels – 1.8 meters – 37 px/m
Scapula: 62 pixels – 1.7 meters – 36 px/m
Humerus: 58 pixels – 1.6 meters – 36 px/m
Femur: 70 pixels – 1.9 meters – 37 px/m
Cervical: 45 pixels – 1.1 meters – 41 px/m (not included in average*)
Neck: 407 pixels – 11.3 meters – 36 px/m
Post-cervical vertebral column: 512 pixels – 13.8 meters – 37 px/m
Total length: 922 pixels – 26.0 meters – 35 px/m
AVERAGE 36 px/m

* I didn’t include the cervical because when I measured it I sorta guessed about where the condyle was supposed to be. That was the odd measurement out, and I didn’t want to tar Lacovara et al. for what might well be my own observer error.

Dreadnoughtus decomposed for GDI - Lacovara et al 2014 fig 2

Here’s the chopped-up Dreadnoughtus I used for my estimate. Just for the heck of it, for the first time out I assigned all of the body regions circular cross-sections. We’ll come back to how realistic this is later. Here’s what I got for the volumes of the various bits:

Head: 0.2 m^3
Neck: 13.9
Body: 32.1
Tail: 4.0
Limbs: 6.8
TOTAL: 57.0 m^3

Okay, this is looking pretty good, right? Lacovara et al. (2014) got 59.3 metric tons using limb allometry, I got a volume of 57 cubic meters using GDI. If Dreadnoughtus was the same density as water — 1 metric ton per cubic meter — then my estimated mass would be 57 tons, which is crazy close given all of the uncertainties involved.

BUT there are a couple of big buts involved. The first is that a lot of sauropods had distinctly non-round body cross-sections (Diplodocus, Camarasaurus). So assuming circular cross-sections might inflate the body well beyond its likely volume. Second is that sauropods were probably much less dense than water (discussed here, here, and here, and see Wedel 2005 for the full scoop). What are the implications for Dreadnoughtus?

Round and Round

It turns out that circular cross-sections are probably defensible for some parts of Dreadnoughtus. By playing around with the 3D PDF of the assembled skeleton I was able to get these orthogonal views:

Dreadnoughtus 3D skeleton orthogonal views

I don’t remember what the pixel counts were for the max height and max width of the torso, but they were pretty close. I measured at several points, too: front of the pelvis, max extent of ribcage, mid-scap. This is probably not super-surprising as the fatness of titanosaurs has been widely noted before this. Here’s a cross-section through the torso of Opisthocoelicaudia at D4 (Borsuk-Bialynicka 1977: fig. 5) — compare to the more taconic forms of Diplodocus and Camarasaurus linked above.

Opisthocoelicaudia torso x-s - Borsuk-Bialynicka 1977 fig 5

Okay, a round torso on Dreadnoughtus I can buy. A round neck and tail, not so much. Look at the skeletal recon and you can see that even with a generous allowance for caudofemoralis muscles on the tail, and diapophyses on the cervical vertebrae, no way were those extremities circular in cross-section. Just off the cuff I think a width:height ratio of 2:3 is probably about right.

But there are some body regions that probably were round, or close enough as to have made no difference, like the head and limbs. So I actually toted up the volume three times: once with circular cross-sections throughout (probably too fat), once with a 2:3 width:height ratio in the neck, trunk, and tail (probably too thin, at least in the torso), and once with the 2:3 ratio only in the neck and tail (my Goldilocks version). Here are the numbers I got:

Dreadnoughtus Table 1 three volumes

 

Air Apparent?

Now, for density. Birds are usually much less dense than water — lotsa cited data in this hummingbird post, the punchline of which is that the average whole-body density of a bunch of birds is 0.73 g/cm^3. Why so light? In part because the lungs and air sacs are huge, and account for 15-20% of the whole-body volume, and in part because many of the bones are pneumatic (= air-filled). For a really visceral look at how much air there can be in the bones of birds, see this post, and this one and this one for sauropods.

In my 2005 paper (almost a decade old already — gosh!), I found that for Diplodocus, even a fairly conservative estimate suggested that air inside the bones accounted for about 10% of the volume of the whole animal in life. That may be higher than in a lot of birds, because sauropods were corn-on-the-cob, not shish-kebabs. And that’s just the air in the bones — we also have several lines of evidence suggesting that sauropods had air-sacs like those of birds (Wedel 2009). If the lungs and air sacs occupied 15% of the volume of the whole animal, and the air in the bones occupied another 10%, that would give a whole-body density pretty close to the 0.73 g/cm^3 found for birds. Sauropods might have been lighter still — I didn’t include visceral, intermuscular, or subcutaneous diverticula in my calculations, because I couldn’t think of any way to constrain their volumes.

What about Dreadnoughtus? As Lacovara et al. (2014) describe, the cervical, dorsal, and sacral vertebrae and sacral ribs are honeycombed with pneumatic camellae (small, thin-walled chambers). And the dorsal ribs have pneumatic foramina and were probably at least partly hollowed-out as well. The caudal vertebrae do not appear to have been pneumatic, at least internally (but diverticula going into the tail can be cryptic — see Wedel and Taylor 2013b). Diplodocus has a big, long, highly pneumatic tail, but Dreadnoughtus has a much longer neck, both proportionally and absolutely, and pneumatic dorsal ribs. So this one may be too close to call. But I also ran the numbers for T. rex way back when and found that air in its vertebrae accounted for 7% of its body volume (this abstract). Pessimistically, if we assume Dreadnoughtus had small lungs and air sacs (maybe 10% of whole-body volume) and not much air in the bones (7%), it’s whole-body density was probably still closer to 0.8 g/cm^3 than to 0.9. Optimistically, a lot of titanosaurs were radically pneumatic and they have may have had big air sac systems and extensive diverticula to match, so a bird-like 0.7-0.75 g/cm^3 is certainly not beyond the bounds of possibility.

Dreadnoughtus Table 2 twelve masses

This table shows a spectrum of masses, based on the three body volumes from GDI (columns) and some possible whole-body densities (rows). Note that the columns are not in the same order as in the first table — I lined them up from most t0 least voluminous here. The 57-ton estimate is the max, and that assumes that the neck and tail were both perfectly round, and that despite the lungs, air sacs, and air reservoirs inside the bones, the whole-body density of Dreadnoughtus was still 1.0 g/cm^3, neither of which are likely (or, I guess, that a real Dreadnoughtus was significantly fatter than the one shown, and that all of that extra bulk was muscle or some other heavy tissue). The 28t mass in the lower left corner is also unrealistic, because it assumes a tall, narrow torso. My pick is the 36t estimate at the bottom of the middle column, derived from what I think are the most defensible volume and density. Your thoughts may differ — the comment thread is open.

Roll Your Own

Dreadnoughtus Table 3 body region comparison

This last table is just a quick-and-dirty comparison of how the volume of the body breaks down among its constituent parts in Plateosaurus (from this post), Giraffatitan (from Taylor 2009), and Dreadnoughtus (based on my “tall neck and tail” GDI). Dreadnoughtus seems to have a more voluminous neck and a less voluminous trunk, proportionally, than Giraffatitan, but I think a lot of that is down to the very fat fleshy envelope drawn around the cervicals of Dreadnoughtus. We are fortunate to count some fearsomely talented paleoartists among our readers — I’ll look forward to seeing what you all come up with in your independent skeletal recons.

So, what’s the take-home? Based on the data available, I don’t think the holotype individual of Dreadnoughtus massed anything like 59 metric tons. I think 35-40 metric tons is much more defensible. But I’m happy to have my errors pointed out and new data and arguments brought to the fore. Your thoughts are most welcome.

References

Continuing with what seems to have turned out to be Brachiosaur Humerus Week here on SV-POW! (part 1, part 2, part 3), let’s consider the oft-stated idea that brachiosaurs have the most slender humeri of any sauropod. For example, Taylor (2009:796) wrote that:

Discarding a single outlier, the ratio of proximodistal length to minimum transverse width (Gracility Index or GI) in humeri of B. brancai [i.e. Giraffatitan] varies between 7.86 for the right humerus HMN F2 and 9.19 for the left humerus HMN J12, with the type specimen’s right humerus scoring 8.69, slightly more gracile than the middle of the range […] For the B. altithorax type specimen, the GI is 8.50, based on the length of 204 cm and the minimum transverse width of 24 cm reported by Riggs (1904:241). However, the B. altithorax humerus looks rather less gracile to the naked eye than that of B. brancai, and careful measurement from Riggs’s plate LXXIV yields a GI of 7.12, indicating that the true value of the minimum transverse width is closer to 28.5 cm. As noted by Riggs (1903:300-301), the surface of the distal end of this humerus has flaked away in the process of weathering. Careful comparison of the humeral proportions with those of other sauropods (Taylor and Wedel, in prep.) indicates that the missing portion of this bone would have extended approximately a further 12 cm, extending the total length to 216 cm and so increasing the GI to 7.53 – still less gracile than any B. brancai humerus except the outlier, but more gracile than any other sauropod species except Lusotitan atalaiensis (8.91), and much more gracile than the humerus of any non-brachiosaurid sauropod (e.g., Diplodocus Marsh, 1878 sp., 6.76; Malawisaurus dixeyi Jacobs, Winkler, Downs and Gomani, 1993, 6.20; Mamenchisaurus constructus Young, 1958, 5.54; Camarasaurus supremus Cope, 1877, 5.12; Opisthocoelicaudia skarzynskii Borsuk-Bialynicka, 1977, 5.00 – see Taylor and Wedel, in prep.)

Implicit in this (though not spelled out, I admit) is that the humeri of brachiosaurs are slender proportional to their femora. So let’s take a look at the humerus and femur of Giraffatitan, as illustrated in Janensch’s beautiful 1961 monograph of the limbs and girdles of Tendaguru sauropods:

Janensch1961-tendaguru-limbs--plates-AJ--giraffatitan-limb-bones

The first thing you’ll notice is that the humerus is way longer than the femur. That’s because Janensch’s Beilage A illustrates the right humerus of SII (now properly known as MB R.2181) while his Beilage J illustrates the right femur of the rather smaller referred individual St 291. He did this because the right femur of SII was never recovered and the left femur was broken, missing a section in the middle that had to be reconstructed in plaster.

(What’s a Beilage? It’s a German word that seems to literally mean something like “supplement”, but in Janensch’s paper it means a plate (full-page illustration) that occurs in the main body of the text, as opposed to the more traditional plates that come at the end, and which are numbered from XV to XXIII.)

How long would the intact SII femur have been? Janensch (1950b:99) wrote “Since the shaft of the right femur is missing for the most part, it was restored to a length of 196 cm, calculated from other finds” (translation by Gerhard Maier). Janensch confused the left and right femora here, but assuming his length estimate is good, we can upscale his illustration of St 291 so that it’s to SII scale, and matches the humerus. Here’s how that looks:

Janensch1961-tendaguru-limbs--plates-AJ--giraffatitan-limb-bones-scaled

Much more reasonable! The humerus is still a little longer, as we’d expect, but not disturbingly so.

Measuring from this image, the midshaft widths of the femur and humerus are 315 and 207 pixels respectively, corresponding to absolute transverse widths of 353 and 232 mm — so the femur is broader by a factor of 1.52. That’s why I expressed surprise on learning that Benson et al (2014) gave Giraffatitan a CF:CH ratio (circumference of femur to circumference of humerus) of only 1.12.

Anyone who would like to see every published view of the humeri and femora of these beasts is referred to Taylor (2009:fig. 5). In fact, here it is — go crazy.

Taylor (2009: figure 5). Right limb bones of Brachiosaurus altithorax and Brachiosaurus brancai, equally scaled. A-C, humerus of B. altithorax holotype FMNH P 25107; D-F, femur of same; G-K, humerus of B. brancai lectotype HMN SII; L-P, femur of B. brancai referred specimen HMN St 291, scaled to size of restored femur of HMN SII as estimated by Janensch (1950b:99). A, D, G, L, proximal; B, E, H, M, anterior; C, K, P, posterior; J, O, medial; F, I, N, distal. A, B, D, E modified from Riggs (1904:pl. LXXIV); C modified from Riggs (1904:fig. 1); F modified from Riggs (1903:fig. 7); G-K modified from Janensch (1961:Beilage A); L-P modified from Janensch (1961:Beilage J). Scale bar equals 50 cm.

Taylor (2009: figure 5). Right limb bones of Brachiosaurus altithorax and Brachiosaurus brancai, equally scaled. AC, humerus of B. altithorax holotype FMNH P 25107; DF, femur of same; GK, humerus of B. brancai paralectotype HMN SII; LP, femur of B. brancai referred specimen HMN St 291, scaled to size of restored femur of HMN SII as estimated by Janensch (1950b:99). A, D, G, L, proximal; B, E, H, M, anterior; C, K, P, posterior; J, O, medial; F, I, N, distal. A, B, D, E modified from Riggs (1904:pl. LXXIV); C modified from Riggs (1904:fig. 1); F modified from Riggs (1903:fig. 7); GK modified from Janensch (1961:Beilage A); LP modified from Janensch (1961:Beilage J). Scale bar equals 50 cm.

Notice that the femur of Giraffatitan, while transversely pretty broad, is freakishly narrow anteroposteriorly. The same is true of the femur of Brachiosaurus, although it’s never been shown in a published paper — I observed it in the mounted casts in Chicago.

Weird.

Calculations

So let’s take a wild stab at recalculating the mass of Giraffatitan using the Benson et al. formula. First, measuring the midshaft transverse:anteroposterior widths of the long bones gives eccentricity ratios of 2.39 for the femur and 1.54 for the humerus (I am not including the anterior prejection of the deltopectoral crest in the anteroposterior width of the humerus) . Dividing the absolute transverse widths above by these ratios gives us anteroposterior widths of 148 for the femur and 150 mm for the humerus. So they are almost exactly the same in this dimension.

If we simplify by treating these bones as elliptical in cross section, we can  approximate their midshaft circumference. It turns out that the formula for the circumference is incredibly complicated and involves summing an infinite series:

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But since we’re hand-waving so much anyway, we can use the approximation C = 2π sqrt((a²+b²)/2). where a and b are the major and minor radii (not diameters). For the femur, these measurements are 176 and 74 mm, so C = 848 mm; and for the humerus, 116 and 75 mm yields 614 mm. (This compares with FC=730 and HC=654 in the data-set of Benson et al., so we have found the femur to be bigger and the humerus smaller than they did.)

So the CF:CH ratio is 1.38 — rather a lot more than the 1.12 reported by Benson et al.  (Of course, if they measured the actual bones rather than messing about with illustrations, then their numbers are better than mine!)

And so to the mass formula, which Campione and Evans (2012) gave as their equation 2:

log BM = 2.754 log (CH+CF) − 1.097

Which I understand to use base-10 logs, circumferences measured in millimeters, and yield a mass in grams, though Campione and Evans are shockingly cavalier about this. CH+CF is 1462; log(1462) = 3.165. That gives us a log BM of 7.619, so BM = 41,616,453 g = 41,616 kg.

Comparison with Benson et al. (2014)

Midshaft measurements and estimates for SII long bones (all measurements in mm)
SV-POW! Benson et al.
Femur Humerus Femur Humerus
Transverse diameter 353 232 240
Transverse radius 176 116 120
Anteroposterior diameter 148 150 146
Anteroposterior radius 74 75 73
Circumference 848 614 730 654
Total circumference 1462 1384
Mass estimate (kg) 41,616 34,000

My new mass estimate of 41,616 kg is is a lot more than the 34,000 kg found by Benson et al. This seems to be mostly attributable to the much broader femur in my measurement: by contrast, the humerus measurements are very similar (varying by about 3% for both diameters). That leaves me wondering whether Benson et al. just looked at a different femur — or perhaps used St 291 without scaling it to SII size. Hopefully one of the authors will pass by and comment.

More to come on this mass estimate real soon!

References

 

My camera had a possibly-fatal accident in the field at the end of the day on Saturday, so I didn’t take any photos on Sunday or Monday. From here on out, you’re either getting my slides, or photos taken by other people.

Powell Museum sauropod humerus

On Sunday we were at the John Wesley Powell River History Museum in Green River, Utah, for the Cretaceous talks. There were some fossils on display downstairs, including mounted skeletons of Falcarius and one or two ornithischians,* and this sauropod humerus from the Cedar Mountain Formation (many thanks to Marc Jones for the photo).

* A ceratopsian and Animantarx, maybe? They were in the same room as the sauropod humerus, so it’s no surprise that I passed them by with barely a glance.

There were loads of great talks in the Cretaceous symposium on Sunday, and I learned a lot, about everything from clam shrimp biostratigraphy to ankylosaur phylogeny to Canadian sauropod trackways. But I can’t show you any slides from those talks, so the rest of this post is the abstact from Darren’s and my talk, illustrated by a few select slides.

Wedel Naish 2014 Sauroposeidon and kin - slide 1 title

Sauroposeidon is a giant titanosauriform from the Early Cretaceous of North America. The holotype is OMNH 53062, a series of four articulated cervical vertebrae from the Antlers Formation (Aptian-Albian) of Oklahoma. According to recent analyses, Paluxysaurus from the Twin Mountain Formation of Texas is the sister taxon of OMNH 53062 and may be a junior synonym of Sauroposeidon. Titanosauriform material from the Cloverly Formation of Wyoming may also pertain to Paluxysaurus/Sauroposeidon. The proposed synonymy is based on referred material of both taxa, however, so it is not as secure as it might be.

Wedel Naish 2014 Sauroposeidon and kin - slide 34 Sauroposeidon characters

Top row, vertebrae of Paluxysaurus. From left to right, the centrum lengths of the vertebrae are 72cm, 65cm, and 45cm. Main image, the largest and most complete vertebra of the holotype of Sauroposeidon. Labels call out features that are present in every Sauroposeidon vertebra where they can be assessed, but consistently absent in Paluxysaurus. Evaluating the proposed synonymy of Paluxysaurus and Sauroposeidon is left as an exercise for the reader.

MIWG.7306 is a cervical vertebra of a large titanosauriform from the Wessex Formation (Barremian) of the Isle of Wight. The specimen shares several derived characters with the holotype of Sauroposeidon: an elongate cervical centrum, expanded lateral pneumatic fossae, and large, plate-like posterior centroparapophyseal laminae. In all of these characters, the morphology of MIWG.7306 is intermediate between Brachiosaurus and Giraffatitan on one hand, and Sauroposeidon on the other. MIWG.7306 also shares several previously unreported features of its internal morphology with Sauroposeidon: reduced lateral chambers (“pleurocoels”), camellate internal structure, ‘inflated’ laminae filled with pneumatic chambers rather than solid bone, and a high Air Space Proportion (ASP). ASPs for Sauroposeidon, MIWG.7306, and other isolated vertebrae from the Wessex Formation are all between 0.74 and 0.89, meaning that air spaces occupied 74-89% of the volume of the vertebrae in life. The vertebrae of these animals were therefore lighter than those of brachiosaurids (ASPs between 0.65 and 0.75) and other sauropods (average ASPs less than 0.65).

Wedel Naish 2014 Sauroposeidon and kin - slide 64 Mannion phylogeny

Check this out: according to at least some versions of the Mannion et al. (2013) tree, Sauroposeidon and Paluxysaurus are part of a global radiation of andesaurids in the Early and middle Cretaceous. Cool!

Sauroposeidon and MIWG.7306 were originally referred to Brachiosauridae. However, most recent phylogenetic analyses find Sauroposeidon to be a basal somphospondyl, whether Paluxysaurus and the Cloverly material are included or not. Given the large number of characters it shares with Sauroposeidon, MIWG.7306 is probably a basal somphospondyl as well. But genuine brachiosaurids also persisted and possibly even radiated in the Early Cretaceous of North America; these include Abydosaurus, Cedarosaurus, Venenosaurus, and possibly an as-yet-undescribed Cloverly form. The vertebrae of Abydosaurus have conservative proportions and solid laminae and the bony floor of the centrum is relatively thick. In these characters, Abydosaurus is more similar to Brachiosaurus and Giraffatitan than to Sauroposeidon or MIWG.7306. So not all Early Cretaceous titanosauriforms were alike, and whatever selective pressures led Sauroposeidon and MIWG.7306 to evolve longer and lighter necks, they didn’t prevent Giraffatitan-like brachiosaurs such as Abydosaurus and Cedarosaurus from persisting well into the Cretaceous.

Wedel Naish 2014 Sauroposeidon and kin - slide 65 Cloverly sauropods

The evolutionary dynamics of sauropods in the North American mid-Mesozoic are still mysterious. In the Morrison Formation, sauropods as a whole are both diverse and abundant, but Camarasaurus and an efflorescence of diplodocoids account for most of that abundance and diversity, and titanosauriforms, represented by Brachiosaurus, are comparatively scarce. During the Early Cretaceous, North American titanosauriforms seem to have radiated, possibly to fill some of the ecospace vacated by the regional extinction of basal macronarians (Camarasaurus) and diplodocoids. However, despite a flood of new discoveries in the past two decades, sauropods still do not seem to have been particularly abundant in the Early Cretaceous of North America, in contrast to sauropod-dominated faunas of the Morrison and of other continents during the Early Cretaceous.

Wedel Naish 2014 Sauroposeidon and kin - slide 66 acknowledgments

That final slide deserves some explanation. On the way back from the field on Saturday–the night before my talk–a group of us stopped at a burger joint in Hanksville. Sharon McMullen got a kid’s meal, and it came in this bag. We took it as a good omen that Sauroposeidon was the first dinosaur listed in the quiz.

For the full program and abstracts from both days of talks, please download the field conference guidebook here.

Actually we had the Jurassic talks today, but I can’t show you any of the slides*, so instead you’re getting some brief, sauropod-centric highlighs from the museum.

* I had originally written that the technical content of the talks is embargoed, but that’s not true–as ReBecca Hunt-Foster pointed out in a comment, the conference guidebook with all of the abstracts is freely available online here.

IMG_5136

Like this Camarasaurus that greets visitors at the entrance.

IMG_5143

And this Apatosaurus ilium ischium with bite marks on the distal end, indicating that a big Morrison theropod literally ate the butt of this dead apatosaur. Gnaw, dude, just gnaw.

IMG_5147

And the shrine to Elmer S. Riggs.

IMG_5191

One of Elmer’s field assistants apparently napping next to the humerus of the Brachiosaurus alithorax holotype. This may be the earliest photographic evidence of someone “pulling a Jensen“.

Cary and Matt with Brachiosaurus forelimb

Here’s the reconstructed forelimb of B. altithorax, with Cary Woodruff and me for scale. The humerus and coracoid (and maybe the sternal?) are cast from the B.a. holotype, the rest of the bits are either sculpted or filled in from Giraffatitan. The scap is very obviously Giraffatitan.

Matt with MWC Apatosaurus femur

Cary took this photo of me playing with a fiberglass 100% original bone Apatosaurus femur upstairs in the museum office, and he totally passed up the opportunity to push me down the stairs afterward. I kid, I kid–actually Cary and I get along just fine. It’s no secret that we disagree about some things, but we do so respectfully. Each of us expects to be vindicated by better data in the future, but there’s no reason we can’t hang out and jaw about sauropods in the meantime.

Finally, in the museum gift shop (which is quite lovely), I found this:

Dammit Nova

You had one job, Nova. ONE JOB!

So, this is a grossly inadequate post that barely scratches the surface of the flarkjillion or so cool exhibits at the museum. I only got about halfway through the sauropods, fer cryin’ out loud. If you ever get a chance to come, do it–you won’t be disappointed.