Brontosaurus, the animal formerly known as Apatosaurus, the animal formerly known as Brontosaurus.

YPM 1980: Brontosaurus excelsus, the animal formerly known as Apatosaurus excelsus, the animal formerly known as Brontosaurus excelsus.

Today is a good day for sauropod science. Since we’re not getting this up until the afternoon, you’ve probably already seen that Emanuel Tschopp and colleagues have published a monstrous specimen-level phylogenetic analysis of Diplodocidae and, among other things, resurrected Brontosaurus as a valid genus. The paper is in PeerJ so you can read it for free (here).

I’ve already been pinged by lots of folks asking for my thoughts on this. I know that the return of Brontosaurus is what’s going to catapult this paper into the spotlight, but I hope what everyone takes away from it is just what a thorough piece of work it is. I’ve never seen so many phylogenetic characters illustrated so well. It sets a new standard, and anyone who wants to overturn this had better roll up their sleeves and bring a boatload of data. I’m also very, very happy that it’s open-access so everyone in the world can see it, use it, question it, tear it apart or build on it. Getting Brontosaurus back is just gravy. Although, being pro-brontosaur enough to have named a dinosaur in honor of Brontosaurus, I’m also pretty happy about that. If you need a quick guide to who’s who now, A. ajax and A. louisae are still Apatosaurus, and B. excelsus, B. yahnahpin (formerly Eobrontosaurus), and B. parvus (originally Elosaurus) are all Brontosaurus. For more details, go read the paper.

A louisae from Wikipedia - full

Apatosaurus lousiae CM 3018: still Apatosaurus. Photo from Wikipedia.

My personal feelings aside, a lot of people are asking how solid is this generic re-separation. I haven’t read the entire paper yet – it’s 299 pages long, for crying out loud – but the separation of Brontosaurus and Apatosaurus seems solid enough. Tschopp et al. didn’t do it lightly, they justify their decision in detail. I don’t hold with the idea that just because two taxa are sisters, means that they cannot be separated generically. As usual in phylogenetic taxonomy, it comes down to what we decide as a community constitutes “diagnosably distinct”. Tschopp et al. have actually put some thought into what that might mean here, and whether you agree with them or not, they’ve at least made all of their evidence and reasoning explicit. That’s both an opportunity and a challenge for critics: an opportunity to pin down exactly where and why you may disagree, and a challenge to do exactly that. You can’t just sit back and say, “I think the analysis is flawed” or “I wouldn’t have coded that character that way” (well, you can, but if that’s all you say, no-one is obliged to take that kind of lazy, drive-by criticism seriously). There are 477 characters here, most of them illustrated, for 81 OTUs, and a lot of post-hoc discussion of the results. So whether you agree with the authors or not, in whole or in part, both fans and critics should dig in and build on this work. Is it the last word on diplodocid taxonomy? Of course not. But it does move the field forward significantly, and the Tschopp et al. should be applauded for that.

There’s a lot more in there than just bringing back Brontosaurus. “Diplodocus” hayi is elevated to its own genus, Galeamopus. Neither of those things are super surprising. There have been rumors since the 90s at least that Brontosaurus might be coming back, and everyone has known for a while that D. hayi was a bit wonky. I was also not surprised to see Australodocus returned to Diplodocidae – when I saw the type material in 2011, it looked diplodocid to me (based on some characters I’ll have to unpack in some other post). More surprising to me are the sinking of Dinheirosaurus into Supersaurus, the finding that Tornieria is not particularly close to Diplodocus, and the uncertain positions of AMNH 460, the American Museum mount, which is an indeterminate apatosaurine pending further study, of FMNH 25112, the Field Museum “Apatosaurus”, which might not even be an apatosaurine at all(!). In several cases, Tschopp et al. come right out and say that X is going to need further study, so if you want to work on sauropods and you’re stuck for project ideas, go see what needs doing.

AMNH mounted Apatosaurus with Taylor for scale

AMNH 460: we don’t know who this is anymore.

As I was scanning the paper again while composing the last paragraph, I almost fell down the rabbit hole. So much interesting stuff in this paper. Even if all you care about is morphology, the hundred or so figures illustrating the phylogenetic characters ought to keep you happy for a very long time. I look forward to reading through the vertebral characters in detail and seeing what I’ve been missing all these years.

I’m contractually obliged to point out that the authors chose to publish the complete peer-review history of the paper, so you can see what the editor (Andy Farke) and reviewers had to say. As always, I think this transparency (and credit for the reviewers) is great for science, and I can’t wait until it’s the norm at more journals.

FMNH 25112 formerly Apatosaurus

FMNH 25112: what even IS that thing?

In addition to the paper, there’s also an interview with lead author Emanuel Tschopp on the PeerJ blog, and a nice shout-out for SV-POW!

Parting shot: why did Tschopp et al. get different results than anyone had previously? Because they used more specimens and more taxa – more data full stop. That’s also why their paper warrants serious consideration. It’s serious work. Let’s go stand on their shoulders.


Tschopp E, Mateus O, Benson RBJ. (2015) A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda) PeerJ 3:e857

In 2012, Matt and I spent a week in New York, mostly working at the AMNH on Apatosaurusminimus and a few other specimens that caught our eye. But we were able to spend a day at the Yale Peabody Museum up in New Haven, Connecticut, to check out the caudal pneumaticity in the mounted Apatosaurus (= “Brontosaurus“) excelsus, YPM 1980, and the bizarrely broad cervicals of the Barosaurus lentus holotype YPM 429.

While we there, it would have been churlish not to pay some attention to the glorious and justly famous Age of Reptiles mural, painted by Rudolph F. Zallinger from 1944-1947.

So here it is, with the Brontosaurus neck for scale:


Click through for high resolution (3552 × 2664).

And here is a close-up of the most important, charismatic, part of the mural:


Again, click through for high resolution (3552 × 2664).

That’s your lot for now. We’ve long promised a proper photo post of the Brontosaurus mount itself, and I’ll try to get that done soon. For now, it’s just scenery.

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:


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:


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:


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):


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?



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:



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.)



  • 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 can it be?


All credit to the Yale Peabody Museum for having the courage to display this historically important object in their public gallery instead of hiding it in a basement. It’s the skull from the original mount of the Brontosaurus (= Apatosaurus) excelsus holotype YPM 1980.

Needless to say, it bears no resemblance at all to the actual skull of Apatosaurus, and the one they now have on the mount is much, much better:


But how did the YPM people ever arrive at this double-plus-ugly skull above? We see a similar skull in Marsh’s (1891) second attempt at restoring the skeleton of Brontosaurus:


But even this is not as ugly and Just Plain Wrong as the physical model they made. (Marsh’s first restoration of the Brontosaurus skeleton, in 1893, had a much less clear skull.)

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

Bizarrely, we’ve never really featured the  YPM 1980 mount here on SV-POW! — we’ve often shown individual bones, but the mounted skeleton appears only in the background of the much less impressive Morosaurus (= Camarasaurus) lentus mount. We’ll fix that real soon.


Last time, we took a very quick look at YPM 1910, a mounted skeleton that is the holotype of Camarasaurus (= “Morosaurus“) lentus, in the dinosaur hall of the Yale Peabody Museum.

Here’s the whole skeleton, in various views. Skip down to the bottom for the science; or just enjoy the derpiness. First, in anterior view:


Here’s a more informative right anterolateral view. As you can see, this little Camarasaurus is in every sense in the shadow of the the much more impressive Apatosaurus (= “Brontosaurus“) excelsus holotype, YPM 1980: click through for the full image:


And here’s the corresponding photo from Lull (1930: figure 1) (see below):

Camarasaurus lentus, holotype skeleton, oblique front view (Full 1930: fig. 1)

Camarasaurus lentus, holotype skeleton, oblique front view (Lull 1930: fig. 1)

It’s interesting to see such a familiar mount in such unfamiliar surroundings. Judging by the cabinets in the background, YPM 1910 was mounted in what’s now the dinosaur hall at Yale — i.e. it hasn’t moved since the photo was taken. But back then, Brontosaurus hadn’t been mounted, and Zallinger’s mural hadn’t been painted.

If you thought this animal looked dumb from the front, check out this left anterodorsolateral view, taken from the balcony above the hall. The foreshortening of the neck makes Cam look like a particularly dense puppy.

(Once more, click through for the full version of the photo, including the much more impressive Apatosaurus.)


Right lateral view, with Zallinger’s justly famous mural in the background. Note the Diplodocus-type double-beamed chevrons in the tail:


Here’s the justly under-rated posterior view:


And finally, Lull’s left posterolateral photo — taken from a position that can’t now be replicated, due to the inconveniently located Brontosaurus. (The Archelon in the background, which was previously featured on SV-POW!, has been moved to the end of the hall since Lull’s time.

Camarasaurus lentus, oblique rear view. Lull (1930: fig. 2)

Camarasaurus lentus, oblique rear view. Lull (1930: fig. 2)

How much of this skeleton is real? Happily, not the skull. We can only hope that the real thing wasn’t quite so troubling. But much of the rest of the skeleton is real bone. To quote Lull (1930:1-3):

In the Yale specimen the entire vertebral column is present from the second or third cervical to the tenth caudal with one or two later caudals. Of the limbs and their girdles there are present the left scapula, right coracoid, both humeri, the left radius and ulna, both ilia, the right pubis and left ischium, and both femora, tibiae and fibulae. One cervical rib is present but no thoracic ribs. The disarticulated sacrum lacked one rib from either side.

(How could Lull have been unsure whether the most anterior preserved cervical was the second or third? C2 in sauropods, as in most animals, is radically different from the subsequent cervicals. He does go on to say that only the centrum of the most anterior vertebra is preserved, but the axis has a distinct anterior central articulation.)

Lull is quite ready to criticise the mount, and notes in particular:

The cervical ribs in the Yale mount are not long enough by half, and the thoracic ribs may be somewhat heavy and their length a little short […] both carpus and tarsus are probably incorrect, as the elements in each instance are fewer than shown, there being no more than two at most. There is apparently no justification for the fore and aft extensions of the distal chevrons, as these were not preserved and the Osborn-Mook restoration was followed. […] A probable error lies in too great an allowance for cartilage between the [pelvic] elements, thus making the acetabulum seem rather large.

He also notes a scheme that sadly never came to pass:

[The holotype of Camarasaurus (= “Morosaurus“) robustus], a very perfect specimen, we intend to mount when the great Brontosaurus excelsus type is completed. The three sauropods, ranging in length from 21 to nearly 70 feet, should make a very impressive group.

They would have done! But in the end it fell to the Museum für Naturkunde Berlin to give us the world’s first three-sauropod combo (unless someone knows of an earlier one?)

Finally; the mounted Yale Camarasaurus also crops up in three of the plates of Ostrom and McIntosh (1966). Plate 60 depicts metacarpals I and II in all the cardinal views except for some reason posterior; plate 61 does the same for metacarpals III and IV); and plate 70 shows the right pubis in every aspect but anterior. Here it is:


Morosaurus lentus [Now referred to Camarasaurus lentus] Marsh (1889) YPM 1910 (holotype). Right pubis (reversed) in medial (1), posterior (2), lateral (3), proximal (4), and distal (5) views; transverse sections through blade (6) and shaft (7). (Ostrom and McIntosh 1966: plate 70)

Judging by this, it’s a beautifully preserved element with some very distinctive morphology. But we’ve been burned by Marsh’s plates before, and I don’t trust them at all any more — at least, not until I’ve seen the elements for myself. Now I wish I paid more attention to Derpy’s pubes.

And on that line, I’m out.


Lull, Richard S. 1930. Skeleton of Camarasaurus lentus recently mounted at Yale. American Journal of Science, 5th series, 19(109):1-5.

Ostrom, John H., and John S. McIntosh. 1966. Marsh’s Dinosaurs: the Collections from Como Bluff. Yale University Press, New Haven, CT. 388 pages including 65 positively scrumptious plates.

Matt’s harsh-but-fair “Derp dah durr” / “Ah hurr hurr hurr” captions on his Giraffatitan skull photos reminded me that there is a sauropod with a much, much stupider head than that of Giraffatitan. Step forward YPM 1910, a mounted skeleton that is the holotype of Camarasaurus (= “Morosaurus“) lentus, in the dinosaur hall of the Yale Peabody Museum. Herp derp derp Full details on this specimen next time! (But a spoiler: the skull isn’t real.)

Here’s a cool skeleton of the South American pleurodire Podocnemis in the Yale Peabody Museum.

What’s that you’re hiding in your neck, Podocnemis?

Laminae! Here’s a closeup:

The laminae run from the transverse processes to the prezygapophyses and the centrum, which I reckon makes them analogues of the PRDLs and ACDLs of sauropods.

As long as I’m posting on Peabody turtles, here’s Archelon. It’s not bad, if you’re into that sort of thing. Which Mike clearly ain’t, but for a good reason, which will be revealed soon.

For more info on vertebral laminae in extant non-dinosaurs, see this post and the lower left paragraph on page 212 of this paper.