Clearing the air about Brontomerus
February 25, 2011
Introduction
Many people in the paleontological community have probably seen the comments about our work on Brontomerus by Jim Kirkland. Most of these comments have been posted on Facebook or sent around by email. We have held off until now in responding to them because we wanted to have everything–both the criticisms and our responses–publicly available to everyone, not in the walled garden of Facebook. Jim has now stated on Facebook that we have permission to post his messages and respond to them, and his longest critique has been posted as a comment on the initial Brontomerus post.
All three of us–Mike, Matt, and Rich, the authors of the new paper describing Brontomerus–have known Jim for some time. He and Rich collaborated in the Cedar Mountain Formation for most of the 1990s, and basically split the catch, with Jim getting most of the dinosaurs and Rich getting the mammals. Matt has known Jim since the late 1990s, and has had many productive conversations with him about sauropods and faunal change in the Early Cretaceous of North America. Mike’s interactions with Jim have been more limited, mainly because they live on different continents, but he has spoken to Jim at meetings and they have exchanged occasional correspondence–always friendly–for years.
Not only has Jim been a friend of ours for some time, he also assisted with the Brontomerus project. Jim first alerted Rich to the existence of the quarry in 1994. Following Rich’s visit to the quarry in September of that year, Jim went out with Scott Madsen and Randy Nydam to collect the fossils of what would become Brontomerus in 1995, and the fossils were prepared under his guidance at Dinamation before being transported to the Oklahoma Museum of Natural History for curation. Jim was also helpful in providing information about the quarry and allowing us to cite personal communications from him in the paper.
We’ve all had long and productive working relationships with Jim for years, and we’d like to see those relationships continue. However, some of his comments are not only factually incorrect but also call our veracity and scientific judgment into question. We feel that the record should publicly be set straight.
In the rest of the post, we have the full text of Jim’s long SV-POW! comment and some of his comments from Facebook, followed by a breakdown of his specific claims and our responses to them.
Jim’s self-described rant
On February 23, Jim sent around an email with the subject “Brontomerus pdf and rant”. ReBecca recently posted a slightly longer version here on Jim’s behalf.
While, it is possible, that Brontomerus is a new species based solely on the juvenile ilium, there is no way based on the minimal contextual information known of this site, that one can say that all the sauropod material we collected at Hotel Mesa pertains to the same species.
When, I was first taken to this site in 1994, it had been opened by guys hoping to develop a commercial Morrison dinosaur quarry. The Bureau of Land Management (BLM) clearly did not OK this! Another party, who told me he had only advised them to get a permit, subsequently took me out to the site.
Examining this site, it was obviously in the Cedar Mt. Fm. [LINK] and of great interest to me, but politics being what they were, I could not get a BLM permit in Utah and as I had recognized a fair number of teeth and claws (theropods and crocs) in the site, I thought perhaps it might be a potential microvertebrate site, so I asked Rich Cifelli at the OMNH if he might be interested in the site. Rich put me on his Utah BLM permit and sent out Randy Nydam and I corralled Scott Madsen (then at Dinosaur National Monument (DNM) and we went out to evaluate the site for microvertebrates and salvage the exposed bones. This took us about 1.5 days (camped for two nights). Unfortunately, the matrix would not break down and thus the site could not be screenwashed for microvertebrates, so Rich lost interest in the site. We prepared all the bones in our (Dinamation Intl. Soc.) lab in Fruita, Colorado before sending them on to the OMNH with his crew when they returned to Oklahoma from working their Utah sites at the end of the following summer.
After, I became Utah’s State Paleontologist in 1999, I expressed interest in reopening the Hotel Mesa Quarry, as this was the only Albian age site in all of eastern Utah, but BLM policy was that all specimens from a given site needed to be reposited at the same repository. Therefore, since Utah paid my salary, it was impossible to justify excavating and preparing a collection of vertebrate materials and sending them to Oklahoma.
A few years ago, Mike Taylor informed me that he and Matt Wedel felt that there was a new sauropod taxon in the collections from Hotel Mesa. I was excited to learn this, as I figured they would seek to open the site and collect more specimens and data concerning this important locality.
I was deeply saddened to learn they had described the new sauropod taxa with no regard to establishing a base of contextual data to support its hypodym.
First there is no evidence to suggest that all the sauropod bones in the site pertain to the same taxon. The Holotype ilium (cute as a bugs ear, I must say, particularly before the shim went through the middle of it, when we flipped the scapula jacket), comes from a much smaller animal that the rest of the reported “hypodym”.
The nearly equivalent and geographically much closer Price River 2 Quarry preserves more than one sauropod taxon among the many hundreds of sauropod bones collected there. Staff at CEUs Prehistoric Museum pointed out that they had long cervicals similar to Sauropossiden and short stouter cervicals. Their new director Ken Carpenter sent me this picture [LINK] showing two morphs of ilia (at top of figure), one with a short prepubic portion and a stout pubic peduncle and on with a long prepubis and slender pubic peduncle. Thus, the Upper Albian part of Cedar Mt preserves a wealth of sauropods and this taxon promises to add to the general confusion regarding North America’s Early Cretaceous sauropods.
Also in terms of stratigraphy (and these guys are not completely at fault here, but if asked I would have told them), the Ruby Ranch Member is Albian in age from all our dating. Abydosaurus mcintoshi from DNM is not from the younger Mussentichit Mbr. but the upper Albian (Chure et al.’s 2010, date of ~104 Ma says that) and as stated in … our abstract coming out at GSA this spring and to be submitted as a manuscript long before that, An unconformity (sequence boundary) separates the basal Cenomanian (98-96 Ma) Mussentuchit from the Albian strata below it. Two date, there are no over lapping parts between Brontomerus mcintoshi and Abydosaurus mcintoshi and these two sites may nearly be equivalent.
The much older upper Barremian to basal Aptian Dalton Wells Quarry low in the Cedar Mt has at least 3 sauropod taxa among the numerous individuals in Brigham Young University’s collection. Remember the Cedar Mountain represents about as much time as the entire Upper Cretaceous.
Basically, the statement that the juvenile holotype belongs to the same taxon as the handful of adult material in the site is a stretch without some supporting taphonomic documentation (more excavation, as the site keeps going. However, the statement is a falsifiable hypothesis so is a scientific statement that needs testing.
Now that we are beginning to excavate our own sauropods, which thank god are at the base of the Cedar Mt. Fm., I’m actually beginning to care about the general taxonomic mess that Albian sauropods are in with the number of taxa described without overlapping parts.
Another observation that I accidentally made was that the reconstruction of the ilium in the paper, differs from that we made in preparing the specimen fresh from the field. These two reconstructions are shown in at the bottom of the picture. We figure this reconstruction from 1995 in Kirkland and Madsen, 2007, Fig. 13E, p. 15). On line at: [LINK]
I’m certainly curious what happened between Rich’s OMNH crew’s picking the specimens up and Mike and Matt’s beginning their research on it. Regardless of whatever happened, it is clear the proportions on the Holotype ilium need to be reappraised.
PLEASE, someone open up this quarry and generate some real information (it is an 8hr drive from Salt Lake City, so I do not have the funds to undertake this). The site is in the Dolores Triangle so the Hotel Mesa Site can only be approached from Colorado, so the Museum of Western Colorado is by far the closest institution to it.
AND; finally, the site is actually in the Burro Canyon Formation not the Cedar Mountain Formation as the name changes as you cross the Colorado River going east. So the stratigraphic level would be, for the sake of accuracy by best referred to as high in the Ruby Ranch Member of the Burro Canyon Formation. This is how it is show on the recently published 1X100,000 geological map of the area. Geological jargon that is useless to argue with unless you are going to publish the justification of changing the convention.
Oh and there are many dozens of sauropods waiting to be excavated in the Ceadar Mountain Formation during the “Age of Ankylosaurs.”
Done spouting off for the minute.
Jim Kirkland
Jim’s Facebook comments
Besides the email/SV-POW! comment, Jim has posted some serious criticisms of the paper on Facebook. These started back in January, when the accepted manuscript of the as-yet-unpublished paper was inadvertently posted on the Acta site. Jim kindly took them down following our request that he do so. However, the deleted criticisms had already been seen by hundreds of people (Jim has 898 Facebook friends) and received many comments, so we feel that it is appropriate to publicly respond to them.
[January 28] Since Abydosaurus mcintoshi and Brontomerus mcintoshi are essentially from the same stratigraphic horizon ~ 150 kilometers apart and have no overlapping parts yet. It is an interesting synonymy since the species name would not change. We have all these sauropod skeletons in the Cedar Mountain, lets not describe scrap.
[January 28] I have wanted to see the Hotel Mesa site (turned over to OMNH) excavated for more than a decade. To describe a dinosaur from scrap salvaged from site and to leave rest rotting in the ground is irresponsible!
[January 28] Jim Kirkland: WTF I oversaw the collection of it all, as salvage over a couple of daysl None of these guys have been to site (more there). No way, you can say anything, but the type illium goes to this species.
Darren Naish: Are you sure that none of the guys have been to the site? Err…Rich Cifelli?
Jim Kirkland: I guarantee it, they would never find it.[February 23] I just realized that they reconstructed the ilium of Brontomeris wrong! See my Hotel Mesa album. It is not thunder thighs, but at most quivering thighs! I would say it throws a big hook into the entire thing.
[February 23] There is no evidence that anything was stolen from the site or smashed for that matter. They simply uncovered it and inquired about a commercial permit.[speaking here of the alleged vandalism of the site by commercial collectors]
Specific claims, and our responses
We’re rather baffled by some of Jim’s statements. Rather than go through the email and Facebook comments line by line or in chronological order, we’ve distilled his criticisms into a number of specific claims, which appear here with our responses.
Claim 1: None of the authors ever visited the quarry.
Source: Facebook, “None of these guys have been to site…I guarantee it, they would never find it.”
Response: This not just incorrect, but insulting. From the paper (Taylor et al. 2011: 76):
One of us (RLC), who had already been working in Lower Cretaceous rocks of the region, was notified about the site through the courtesy of James I. Kirkland, and was guided to it by Bill Hawes of Grand Junction, Colorado, in September 1994. Additional collecting at the site for OMNH was conducted by Randall L. Nydam and James I. Kirkland in March 1995.
In an email to Matt and Mike with permission to cite, Rich wrote:
I took the information directly from my field notes and I remember the place pretty well. Of course I was there!
Claim 2: We erred in describing the site as being part of the Cedar Mountain Formation rather than the Burro Canyon Formation.
Source: SV-POW! comment, “the site is actually in the Burro Canyon Formation not the Cedar Mountain Formation as the name changes as you cross the Colorado River going east. So basically the proper description of the site would say, it is in the upper part of the Ruby Ranch Mbr. of the Burro Canyon Formation.”
Response: We acknowledge this in the paper, and clearly state that our discussion of the site as part of the CMF is one of convenience (Taylor et al. 2011: 76):
Stratigraphically, OMNH V857 lies in a sequence of Lower Cretaceous rocks interposed between the Morrison Formation (Kimmeridgian) below and the Dakota Formation (Cenomanian) above. Westward, these rocks are recognized as the Cedar Mountain Formation; eastward, the Burro Canyon Formation. The arbitrary dividing line between these entities is generally placed at the Colorado River (Stokes 1952; Tschudy et al. 1984) which technically places OMNH V857 within the Burro Canyon Formation. However, we will refer to the locality as belonging to the more widely recognized Cedar Mountain Formation, as it is in this formation that comparable specimens are known, and the stratigraphy and sedimentology do not change across the arbitrary border.
It is also worth noting that in his long comment, Jim himself discusses the quarry as part of the Cedar Mountain Formation, presumably out of convenience: “Examining this site, it was obviously in the Cedar Mt. Fm.” (from the third paragraph of his SV-POW! comment).
Claim 3: The quarry probably has more than one sauropod taxon, because other CMF quarries sometimes have more than one sauropod taxon. (conflicts with Claim 8)
Source: SV-POW! comment, “First there is no evidence to suggest that all the sauropod bones in the site pertain to the same taxon. The Holotype ilium (cute as a bugs ear, I must say, particularly before the shim went through the middle of it, when we flipped the scapula jacket), comes from a much smaller animal that the rest of the reported “hypodym”.
“The nearly equivalent and geographically much closer Price River 2 Quarry preserves more than one sauropod taxon among the many hundreds of sauropod bones collected there.”
Response: This is a possibility we discuss extensively in the paper (Taylor et al 2011: 79), but so far there is no evidence to support it. All of the material is consistent with a single taxon, most likely a basal somphospondyl, but conservatively a camarasauromorph. (We plan to talk much more in a subsequent article about this tentative assignment of all the material to a single taxon.)
There is a more general point to be made here. Any time someone erects a new taxon, the idea that the taxon is actually distinct from other, previously named, taxa is a hypothesis subject to further testing. Anytime someone refers material to a taxon, that is likewise a hypothesis. If we pretended to be any more certain about the referral than we actually are, we’d be lying. But we’d be equally in error if we didn’t point out that the null hypothesis is that all of the material belongs to one taxon. If contrary evidence comes to light, we’ll take it into account and move on–that’s how science works.
If someone find a complete titanosaur skeleton with an ilium like the holotype of Brontomerus, and someone else turns up a complete rebbachisaur with a scapula like the one currently referred to Brontomerus, great! Name the rebbachisaur (a North American rebbachisaur would rock!), remove the scapula from the Brontomerus Referred Material list, and move on. As we made clear in the paper, Brontomerus is based on, and diagnosed by, the holotype ilium alone.
Claim 4: There is no evidence that anything was stolen or destroyed from the site.
Source: Facebook, “There is no evidence that anything was stolen from the site or smashed for that matter. They simply uncovered it and inquired about a commercial permit.” Also repeated second-hand as a comment on Dinosaur Tracking, here.
Response: In an email with permission to cite, Rich wrote:
Yes, of course it had been excavated: we have proof in my notes and in Randy Nydam’s field notes. The comments about bone strewn around and being used to hold pieces of blue tarp are, unfortunately, accurate.
What’s more puzzling is that all three of us have received emails from Jim going back to 2007 that clearly state that the quarry was vandalized. For example (and note the explicit permission to cite):
Message-Id: <47DE4651.784D.00CA.0@utah.gov>
Date: Mon, 17 Mar 2008 10:22:12 -0600
From: James Kirkland
To: Mike Taylor
Subject: Re: Another Hotel Mesa pers. comm.
[…]. The small ilium was under the scapula (completely hidden and the shim went through the middle of it, but we were able to prepare it with it’s entire margin reconstructed. (collected by Jim Kirkland, Scott Madsen, & Randy Nydam from site that had been uncovered previously by vandals). […]
Site this.
Claim 5: The quarry is full of more and better sauropod material.
Source: Facebook, “To describe a dinosaur from scrap salvaged from site and to leave rest rotting in the ground is irresponsible!”
Response: Any material exposed near the surface at Hotel Mesa in 1994 and 1995 is long gone by now, crumbled by 16 years of freeze/thaw cycles and erosion by wind and water. There may be more material deeper down, a possibility that we have always acknowledged, but since no one has ever seen that material, it is impossible to say if it’s better than what we have, or if it even exists at all. This is actually not unusual for dinosaurs; many taxa are known from quarries that are not worked to exhaustion and later produce more material. One of our express aims in writing this paper was to to provide the impetus for further excavation in the quarry, and there was no prospect of that happening before we started working on it.
Claim 6: It was irresponsible of us to name a new dinosaur based on such incomplete material.
Source: Facebook, “We have all these sauropod skeletons in the Cedar Mountain, lets not describe scrap.”
Response: Although incomplete, the material still bears numerous autapomorphies that clearly indicate that it is a new taxon based on currently available data (see point 3, above, on hypotheses).
Since the material in the quarry was not articulated, we would have had to choose an isolated element as the holotype even if we had more material (and the ilium would still have been the obvious choice because it is so unusual). This is absolutely critical: in a bonebed of disarticulated elements, it wouldn’t matter if we had just the ilium or 5000 bones, we’d still have to pick one element as the holotype and refer everything else to it. Anyone describing a new taxon from disarticulated elements in a bonebed faces the same decision: for example, Kirkland et al. (2005), in their description of the basal therizinosaur Falcarius, nominated a partial braincase as the holotype and referred all the other material.
Claim 7: We erred in attributing Abydosaurus to the Mussentuchit member of the Cedar Mountain Formation.
Source: SV-POW! comment, “Abydosaurus mcintoshi from DNM is not from the younger Mussentichit Mbr. but the upper Albian (Chure et al.’s 2010, date of ~104 Ma says that) and as stated in … our abstract coming out at GSA this spring and to be submitted as a manuscript long before that,”
Facebook, “Abydosaurus mcintoshi and Brontomerus mcintoshi are essentially from the same stratigraphic horizon” [Brontomerus is from the Ruby Ranch member]
Response: The only published peer-reviewed work on the Abydosaurus quarry (Chure et al. 2010) places it in the Mussentuchit member. Jim’s abstract was not available to us when we were writing the paper, and if we had the option to choose between the conclusions of a peer-reviewed paper and those of an unpublished abstract, we’d still have followed the paper. Abydosaurus could actually be from the Ruby Ranch member, but we will wait for the published evidence, and to see what Chure et al. have to say in response.
Claim 8: Because Abydosaurus is from the Ruby Ranch member, Brontomerus might simply be Abydosaurus. (conflicts with Claim 3)
Source: Facebook, “Abydosaurus mcintoshi and Brontomerus mcintoshi are essentially from the same stratigraphic horizon ~ 150 kilometers apart and have no overlapping parts yet. It is an interesting synonymy”
Response: The hypothesis that Abydosaurus is from the Ruby Ranch member is far from convincingly demonstrated (see above). The Ruby Ranch member has at least two sauropods other than Brontomerus, and the Yellow Cat member has between three and five, so the idea that there is only one sauropod genus in each member of the CMF, and that therefore Brontomerus must be synonymous with Abydosaurus, is insupportable. Potential synonymies among Early Cretaceous North American sauropods are acknowledged and discussed extensively in the paper (Taylor et al. 2011: 87-88, 91-92).
Also, we note that back in January, Jim was concerned that Brontomerus was synonymous with Abydosaurus (not enough new sauropods in the quarry), and now in his comment he is concerned that there might be more than one taxon in the quarry (too many new sauropods). Which is it, and what aspects of our discussion of these problems in the paper does he find incomplete?
Claim 9: Jim’s photo of the reconstructed ilium shows that our reconstruction is wrong and that our conclusions are therefore suspect.
Source: Facebook, “I just realized that they reconstructed the ilium of Brontomeris [sic] wrong! See my Hotel Mesa album. It is not thunder thighs, but at most quivering thighs! I would say it throws a big hook into the entire thing.”
Response: Yesterday (February 23) we received an email from Jim, with this photo:
The body of the email:
I just realized that the ilium is reconstructed wrong in the paper. Here is how we reconstructed it straight in from the field..
Sorry guys.
Jim’s reconstruction includes a small piece of bone in the dorsal margin of the iliac crest that is not in our reconstruction. Here’s a comparison Mike put together to show which bits are which:
Jim’s reconstruction is different from ours, but that does not automatically make it correct. This just in by email (with permission to cite) from Brontomerus co-author Rich Cifelli, who is curator at the Oklahoma Museum of Natural History where the fossils are curated:
From: Rich Cifelli
To: Mathew Wedel, Mike Taylor
Date: 25 February 2011 00:45
Subject: restorations of Kirkland vs. Taylor et al.
Gentlemen:
I have re-examined the various pieces of the holotype ilium (OMNH 66430). Our restoration stands as the only one that is really plausible, and is the best match considering the thickness, curvature, preservation, and surface texture of the three main pieces (large section including acetabulum, peduncles, and pre-acetabular blade; followed by thin strip of margin; followed posteroinferiorly by “Oklahoma-shaped” piece with margin). The other piece shown by Kirkland (roughly rhomboidal in outline) was omitted by us because it does not include any of the bone margins (contra Jim’s restoration) or contacts with other pieces: it fit somewhere in the large space posterior to the pre-acetabular blade and dorsal to the acetabulum.
Kirkland’s restoration cannot be “straight from the field” because it is obviously incorrect in placement, orientation, and side shown for the rhomboidal piece. As said, this fragment does not contain any of the bone margin: all of the edges, including that which he depicts as lying along the posterior-posterodorsal margin of the ilium, are jagged and broken. Color, surface texture, and an important morphological feature also show that he depicts this piece upside down. That feature is a ridge which separated attachment places for two sacral ribs, shown by Kirkland to be lateral (facing outward) but which of course should be medial.
But, all right, suppose Jim had been right about how the pieces should fit together: here’s a new recon by Mike that follows the photo Jim sent. Note that all the pieces fit comfortably within the very same dotted reconstruction line as in Fig. 2 of the paper.
It is also important to realize that the ilium is oriented differently in the two photos. The photo on the left in the comparison image, from Taylor et al. (2011: fig. 2), is a straight lateral view, looking straight down the laterally-oriented axis of the acetabulum. The preacetabular blade of the ilium angles out anterolaterally, as shown in our Figure 2B. In Jim’s photo, on the right of the comparison image, the preacetabular blade is lying flat on a table, which puts the acetabulum at an angle to the camera; the photo is effectively in posterolateral view rather than orthogonal, and this is the source of all the significant differences between the two photos. Take Jim’s reconstruction, mentally rotate it laterally through 20-30 degrees to look straight down the acetabulum, and his post-acetabular expansion would fit comfortably into the dotted line we drew, as Mike’s new recon shows.
The diagnostic features (autapomorphies) of the ilium are (Taylor et al. 2011: 78):
- Preacetabular lobe 55% of total ilium length, longer than in any other sauropod;
- Preacetabular lobe directed anterolaterally at 30 degrees relative to the sagittal plane, but straight in dorsal view and vertically oriented;
- Postacetabular lobe reduced to near absence;
- Ischiadic peduncle reduced to very low bulge;
- Ilium proportionally taller than in any other sauropod—height is 52% of total length, compared with a maximum of 45% in other sauropods.
If Jim’s reconstruction were right, it would only change the margin of the iliac crest, so it couldn’t affect characters 1, 2, or 4. His reconstruction still shows the postacetabular lobe reduced to near-absence (3), which still leaves the ilium proportionally taller than in any other sauropod (5). In short, the version he favors doesn’t affect the proportions or autapomorphies one whit.
The alternative reconstruction is valuable because it points out the existence of a missing piece of the wing of the ilium. However, not only is it wrong in the position of that piece, even if it was right it wouldn’t affect our morphological, taxonomic, or functional interpretations of Brontomerus at all.
Conclusion
Thanks for slogging through this long, probably not-terribly-interesting post. We’ll soon return to normal service, with more information on Brontomerus — and that awesome life restoration.
References
- Chure, D., Britt, B.B., Whitlock, J.A., and Wilson, J.A. 2010. First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition. Naturwissenschaften (online preprint). doi:10.1007/s00114-010-0650-6
- Kirkland, J. I., Zanno, L. E., Sampson, S. D., Clark, J. M. and DeBlieux, D. D. 2005. A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah. Nature 435: 84-87.
- Taylor, M. P., Wedel, M.J., and Cifelli, R.L. 2011. A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA. Acta Palaeontologica Polonica 56(1):75-98. doi: 10.4202/app.2010.0073
Sauropod Vertebra Picture of the Week 
February 25, 2011 at 4:58 am
As a lawyer by training, I find this sort of post fascinating. Quite apart from the fun of the fight, the explanations of the differences, the claims and responses are illuminating for me, even if not fun for you to have to set out.
February 25, 2011 at 6:26 am
Really awesome read. If we had this kind of conversation about every paper that gets published, think of how much better science would be.
February 25, 2011 at 9:36 am
Mike,
I’m going to call you on two of these points, but won’t be aggressive about it.
1. Claim 2- Stratigraphic Nomenclature:
“However, we will refer to the locality as belonging to the more widely recognized Cedar Mountain Formation, as it is in this formation that comparable specimens are known, and the stratigraphy and sedimentology do not change across the arbitrary border.”
The stratigraphic nomenclature (just as the Judith River and Two Medicine Fms. are divided by a US state line) is pretty solid without review, but it is [seemingly] unseemly to abandon applicable nomenclature for “convenience.” You may initiate the process to condense the stratigraphy into a single nominative unity, but until then, you are causing confusion with researchers (especially geologists) who must use the reference data you provide. Looking into this, and reading that you called it CMFm instead of BCFm because a river doesn’t define a stratigraphic separation, means that a researcher can still call it BCFm and indicate this problem, only they now have to do extra work because of it. This type of discussion doesn’t help.
2. Claim 9- Reconstruction of Ilium
Rich is probably right about the relative position of the elements along the dorsal margin of the ilium. What seems problematic is that even in restoring the ilium after your own, you magically find your own conclusion verified. This is called confirmation bias.
(BTW, I can see why you said you were busy in the email… wow.)
All that aside, it’s good to see some of the background discussion, but this all doesn’t really add to our discussion. I must agree with Jim on two other points: describing a taxon on the basis of “scrap” as well as juvenile material is highly problematic, as you cannot account for adult morphology in regards to missing material, and this includes speculation about what that missing material actually contains or tells us (such as the abbreviated postacetabular ala). Adult morphology often differs from juvenile, and the form of the ilium can differ (if even just a bit) potentially altering the very proportions that render another of your autapomorphies. (I am unfamiliar with analyses that actually test variation between juvenile and adult pelvic morphology, so am willing to be wrong on this argument’s extension to sauropods in general or Brontomerus in specific.)
But there is a second point (yes, that was all one point): Jim argues that association of juvenile and adult material in a collective (juvenile ilium beneath adult scapula doesn’t raise a red flag?) makes problems of separating polychthonous from monochthonous assemblages, when there is NO overlapping material? I would be wondering when the decision NOT to assume they all belonged to the same animal occurred, and how it was abandoned.
Excellent discussion above, nonetheless.
February 25, 2011 at 12:42 pm
This is fascinating… but not primarily for the reasons you think. I do hope you and Jim can unlock horns for just a second and remember Sayre’s Law: “In any dispute the intensity of feeling is inversely proportional to the value of the stakes at issue.”
If you’re about to destroy a long friendship, in print, over the exact placement of three fragments of ilium, then it’s time to have a beer together and get some perspective.
February 25, 2011 at 1:08 pm
Hi, Kattoro. I hope we made it clear in the post — we certainly intended to — that we’re not looking to destroy any friendships! We would love to get together for a beer, but since I’m in England, Matt in California, Rich in Oklahoma and Jim in Utah, it’s not just a matter of popping over the road to the pub.
In the mean time, the issue is that Jim’s criticisms were made public (i.e. not just discussed over a beer with the three of us). Unfortunately, that means that unless we wanted to let them stand unchallenged (and we didn’t), we had to make our response public, too. We’re not particularly intending to get into a long, drawn-out argument here (although if Jim wants to respond in a comment then of course he’s more than welcome to do so). But we couldn’t just leave things as they stood, so that in a couple of weeks when the Chinese whispers have done their job, it became “common knowledge” that we screwed up the history, geology, taxonomy, reconstruction and functional morphology.
February 25, 2011 at 5:11 pm
A response to Jaime (note: I was not directly involved in the Brontomerus paper, nor have I discussed what you’re about to read with the other two-thirds of SV-POW!)…
Firstly, at the risk of sounding rude (sorry), it is very difficult to understand anything you write. You need to simplify your arguments: stop adding layers of complexity to your writing when they are not needed. I offer this as a bit of friendly advice.
Secondly, I cannot see from your criticisms that you have read the paper, or understood the argument made therein, or in the article here. You seem to have just flat-out ignored everything stated in the article above. The point is well-made above that Jim’s criticisms are either erroneous, contradictory, or refer to unpublished work that could not, or cannot, be credited in the paper. Taylor et al. explained very clearly in their paper what they did as regards holotypes and the suggested referral of additional material. Future work may indeed show that the quarry includes more than one taxon, or that the ilium has been reconstructed incorrectly, but the conclusions reached by Taylor et al. are well argued in their paper. I put it to you that you have responded here simply because you like playing Devil’s advocate, not because you have understood the points involved.
February 25, 2011 at 7:04 pm
Posted for Jim:
“Brooks gave me the info on the paper, telling me it had come out. I guess it did and was retracted…? So I reacted as if the target had been launched……Anyway I had no clue that they wanted it embargoed at time and as they say I pulled everything down immediately when I learned otherwise.”
February 25, 2011 at 7:17 pm
Posing for me this time…
Regarding Claim 2: I kind of agree with Jamie about the nomenclature problem re: Cedar Mt./Burro Canyon. I work in Colorado (mostly) and it gets confusing for us! When we are working in Rabbit Valley we have Cedar Mountain in the Valley (due to the position of the river). When we work over by the Fruita Paleo Area we have Burro Canyon. All due to where the river currently flows being the boundary. It does make it very confusing and I think rather than making the situation more complicated it would be nice if people would either go with the way it is currently set up with the USGS or just revise the nomenclature. I realize you all mention this in your paper, and I am glad you all did. It’s not like you just ignored the problem (even Jim refers to the site as Cedar Mt., out of habit I am guessing).
Regarding Claim 5: It appears that everything on the surface was collected. So everything that was left in place and never excavated is probably still ok. Erosion does not happen that fast out here! I have visited several sites that were partially collected in this area over ten to twenty years ago, and there is very minimal erosion taking place at these site, if any. Of course different sites will change differently over the years. Who knows – the slope of the quarry may have led it to be more covered over time. Or not. I guess someone is just going to have to drive out there and actually check the site to see what its current state is. ;)
February 25, 2011 at 7:40 pm
Hi, ReBecca, thanks for your thoughts. Rich and I have been talking about the possibility of going back out to the site this summer. I’m mainly worried about water seeping into any bones near the surface and freezing. In my experience with that kind of freeze/thaw damage, slow erosion can actually be bad, because the bones near the surface can be completely powderized before they’re exposed (although it’s debatable whether that’s any worse than fast erosion, where the bones just wash away–erosion giveth, and erosion taketh away). We’ll just have to get out there and see, and keep our fingers firmly crossed in the meantime.
February 25, 2011 at 7:58 pm
Hi Matt, Cool! Glad to hear it. I hope that maybe the capping sandstone might help with the water seeping issues. I agree, that kind of long term damage can be very bad. It will be good to see how the site has held up over the years.
February 26, 2011 at 2:16 am
Darren,
Instead of blatantly claiming that I “have not read the paper” when dismissing my arguments, or not even trying to read what I wrote (okay, maybe sometimes I am confusing, ReBecca seems to have understood ONE of my ponts), you managed to not engage the points I made. In the interests of beind rude because of the tone I received, it is important to point out that a comment claiming I have not some something that is explained when my argument is in direct contradiction to this ignores the issue that perhaps the paper has not made a substantive argument on that point.
1. The stratigraphic issue is not resolvable because Taylor et al. simply claimed their use of one term is more convenient. It is convenient for them, at that time, and likely to be problematic down the road, which was my point.
2. Where does using juvenile material ever become a valid proxy to adult material? I asked this both authentically and rhetorically, simply because ontogentic variation is UNDERSAMPLED in sauropod description (and asked for clarification) while in other taxa (especially birds and lizards) juveniles are more likely to be confused among taxa than segregated taxonomically. Despite this, a juvenile ilium beneath an adult scapula cannot be used to demonstrate a damn thing other than taphonomy. Yet the authors established a hypodigm on the basis of one of these bones and dumped the rest in there based on association. They should have stuck to the ilium and been a lot less confusing on that point.
Where in all this is this argumentation “confusing”?
February 26, 2011 at 2:41 am
1. The stratigraphic issue is not resolvable because Taylor et al. simply claimed their use of one term is more convenient. It is convenient for them, at that time, and likely to be problematic down the road, which was my point.
It won’t be problematic for anyone who bothers to read the paper. We didn’t formally reassign the rocks or anything, we just discussed the material in the context of the much more extensive and better known CMF with which it is laterally continuous–and explicitly noted that, yes, we were doing it out of convenience. If you’re still unhappy about that, I suppose we’re at an impasse.
Where does using juvenile material ever become a valid proxy to adult material?
Um, when the animal is already a third grown and the element in question is not likely to be subject to much ontogenetic change? We’ll expand on this in a future post, but in general appendicular elements of sauropods grow isomorphically, so that those of juveniles are the same shape as those of adults, only smaller. Mike and I spent a lot of time in the basement of the Humbolt museum looking at the vast collection of adult and juvenile sauropod material from Tendaguru, we canvassed all of the relevant literature on ontogenetic change in sauropods, and we solicited the opinion of colleagues who work on dinosaur ontogeny. And in none of these sources did we find any evidence for major shape changes in the ilium over ontogeny.
Since we’ve already done our homework on this, it’s time for you to show that we’re in error, instead of just asserting it over and over without presenting any evidence to support your claims.
Yet the authors established a hypodigm on the basis of one of these bones and dumped the rest in there based on association. They should have stuck to the ilium and been a lot less confusing on that point.
You don’t seem to know what the term ‘hypodigm’ means. We’ve already dealt with this twice, once in the paper and now again in the post. But just to make things interesting, let’s try this: explain to us why it was okay for Kirkland et al. (2005) to diagnose Falcarius on the basis of an incomplete braincase with 3 autapomorphies, but wrong for us to diagnose Brontomerus on the basis of an incomplete ilium with 5 autapomorphies. (For everyone else: we’re not claiming that Kirkland et al. did anything wrong; as I explained in the post, this is just what you have to do with disarticulated material. I’m just curious about how Jaime justifies accusing us but not, well, everyone else who’s ever worked on a bonebed.)
If Darren accused you of not reading the paper, it’s because your arguments show that either you haven’t read it or didn’t understand it. To wit:
I would be wondering when the decision NOT to assume they all belonged to the same animal occurred, and how it was abandoned.
Dealt with on page 80 of the paper.
Come back when you’ve got something some evidence to go with your accusations.
February 26, 2011 at 3:10 am
I agree with Matt on this one. . .although we certainly need to look at ontogeny, it is ridiculous to throw out a diagnosable specimen simply because it’s a juvenile (especially when the ontogeny of related animals is relatively well-understood). Juvenile ≠ useless. (yes, even for ceratopsids – although you have to be careful there, many features of specific merit show up quite early in ontogeny! check out some of the juvenile Styracosaurus specimens from DPP as a great example of this – sure the spikes are small, but they sure as heck aren’t Centrosaurus!) You have to be careful, yes, but it’s not as if all organisms are non-descript blobs until adulthood.
February 26, 2011 at 10:04 am
The point regarding the ilium shape is this: the element as preserved apparently contains at least four disarticulated pieces. These can, at first blush, be combined in several plausible ways. As such, the most parsimonious solution would be that the postacetabular blade had about the same relative size as with other sauropod taxa. The analysis by the authors however, resulted in a interpretation representing a highly exceptional morphology. The shape would be so extraordinary that it forced the authors to assume additional exceptional qualities, either in the build or the behaviour of the species.
The paper offers some insight into the exact process of analysis. It begins by stating that “The relative positions and orientation of the two smaller fragments can not be definitely ascertained…”. Nevertheless, their probable position can be deduced from the fact that “they appear to be parts of a single large fragment broken at the point where we have reconstructed them as touching; and if this interpretation is correct then the curvature of the pair indicates which side must be oriented laterally”.
This statement poses some problems for the reader of the paper: when looking at the picture it is not at all obvious that the smaller piece was once directly connected to the larger. He can only see a lack of conformity in edges, rim curvature and colouration.
The assumption that their relative positions have been correctly reconstructed is essential to the entire shape interpretation. Because the larger piece is placed to the back of the smaller, it cannot be plausibly orientated more horizontally allowing a more normal posterior blade surface, as this would result in a, for a sauropod, highly aberrant curvature. However, if Kirkland was correct in placing the larger fragment in front of the smaller, this problem is largely solved: the ilium would then be still very deep, but both more balanced in relative blade proportions and more normally curved.
So, what were the exact considerations leading to the conclusion that the smaller piece was in front? And at which point does the “finished bone” dorsally to the ischiadic peduncle stop and breakage begin?
February 26, 2011 at 10:30 am
OK, evidently it’s time for a post about the ilium :-)
Stay tuned …
February 27, 2011 at 9:51 am
[…] in discussing this taxon, some issues arise. As part of a debate between the authors and one of the discoverer’s of the locality at which the specimens for […]
February 27, 2011 at 9:53 am
I’d like to clear something up before I make any further posts on the subject of this taxon, and then my response went on too long (as it inevitably does).
So I’ve posted it here: http://qilong.wordpress.com/2011/02/27/to-play-devils-advocate/
February 27, 2011 at 11:38 am
Now for some meat:
Matt at least responded to some specific issues I brought up, unlike Darren, who commented on how I said a thing and my mode of argument, rather than what I said.
However, the form of Matt’s response follows Darren’s in that he argues that I have not read the paper, or argue that I do not understand. This is wrong. I have read the paper, but while it is possible I do not understand what they meant, I understand what they wrote. Matt (and Mike) have the additional benefit, and perhaps flaw, of being personally involved in the paper, and are — as a general rule — prone to its defense.
The paper lists in the systematic section:
This is inaccurate, and actually wrong. Yes, you use a device of convenience, but this convenience serves no purpose beyond the point following it on the relative age of the allocated strata. As I explained in that very post you quoted, this confuses future workers when they find the geological series used to catalogue this specimen, and the paper, and the commentary, and recover confusion. It does not matter that you FEEL the nomenclature should reflect what seems like reality (that BCF and CMF are equivalent and arbitrarily divided by a river: they are defined geologically, with their own type localities and analyses defining their extent and exposure. Unlss you are intending to revise the geological nomenclature, which is not apparent in the paper, then like biological nomenclature, you must do so formally, and through the proper channels. This rebuttal is both based on the process you used and the seeming indifference to the issue this has for the work.
As an analogy, Mike Taylor is currently involved in appealing to the ICZN for formal revision of the type species of *Cetosaurus*, and the process involved is precise and qualified at every step by formal processes. Yet none of this was considered for the geology relevant. Mike Taylor et al. are not simply arbitrarily selecting a type species and asserting it should be this way, nor should they. Why this for the geology, however minor it may seem of a point? Why could the issue not be raised in the introduction, handled as a “problem,” then let slide, while noting in the Syst Palo section that the BCF is equivalent and effectivley the same thing as the CMF, and leave it at that?
As an anticipatory rebuttal to a response, let me note: The term “Cedar Mountain Formation” is used only in five locations throughout the paper: in figure captions, in the Syst Paleo section, in the formation discussion noted above, and in the comparison sections preceding and following the phylogenetic analysis section. In the comparison section and thereafter, it is used primarily to establish “likely” sauropods with which it may compare, and is distinguished from them based on the member to which each of these taxa belong. Nowhere in these sections was there need to use CMF over BCF, save in the geologic overlap table and discussion in comparisons, presumably to establish the equivalency of the Hotel Mesa Q with the RRM and thus to the succession of sauropods in the CMF. I argue however that this is hardly necessary, as the discussion of the formation’s equivalency was already handled, and a simple column could have been added to clarify the BCF position relative to the CMF. Sometimes “simplicity” is more complex than “complexity,” and I aver the two are relative.
This is a non-starter. You assume I have some “feeling” mixed in with this discussion.
February 27, 2011 at 11:38 am
You’ve published on the lack of variation in proportions or morphology in sauropods from 1/3 adult size and up? Where? My understanding is that so far, most studies on juvenile sauropod material are partial to fragmentary, with Rapetosaurus krausei‘s initial description being an exception.
OK, I’ll bite. It isn’t (at least as far as the assertion goes: if the braincase was found disarticulated from any other element and the material was found withou any form of articulation). I’ll get to the second part of the assertion (number of autapomorphies) after this.
I dislike bonebed taxa in general (where a sample block of disarticulated bones can reasonably be interpreted as a single taxon when there is a lack of overlap across most of the elements), and this is nowhere more prevalent than in some portions of the polychthonous assemblage from the various blocks recovered from the Whitaker Quarry (Ghost Ranch). Disimilarly, bonebed taxa such as Silesaurus opolensis (whose holotype is a dentary with conjoined splenial) involve some disarticulation, but a large number of articulated specimens (as in fact, most of the Whitaker Quarry material). But ti should never be assumed that because most of the specimens are consistent, all of them are. This must be done on a piece-by-piece basis, where found separate. Kirkland handled something like this in a unique way, followed with the Hotel Mesa Quarry, with the Nedcolbertia section of the Dalton Wells Quarry, where none of the material is articulated, but often overlapping and associated: A single element is chosen, one which is diagnostic for the observer, and the remainder are described apart from one another and each element given its own specimen number — the same is true of all specimens collected in the same fashion in the CEUM. A reasonable claim can be made that the material belongs to a single individual because they are generally consistent in size. Yet the quarry showed multiple individuals, different in size, and Kirkland made the assumption that some of the material may NOT belong to a single taxon, and certainly not to a single individual, and as such refrai9ned from assuming much if anything about their proportions.
But you conflated the argument with number of apomorphies as well, and on that one I think you may have greater difficulty qualifying your point: Relative quantity of diagnostic features has not, ever, been determined as a viable measure of a taxon’s value; it’s been asserted, but never determined. I made this argument in contradiction to Mike Taylor on separating brancai from Brachiosaurus, not only because the result did not result in increased phylogenetic resolution (simply using the species separately will do this, and this Taylor DID demonstrate), but because the subjective recognition of “apomorphies” is relative to the observer: tomorrow, Taylor can assert eight of the characters used are ineffective in separating the taxa (I doubt it), and that would decrease the separatedness as argued.
February 27, 2011 at 11:38 am
Matt attempts to bring my attention to Page 80 of the paper when responding to my comment about affirming that all of the material did not belonged to a single animal, but no discussion of this sort occurs on this page. The only comment is:
This does not answer my question, which was, as Matt quoted directly:
But perhaps Matt got the page numbers wrong; on the preceding page (pg.79), the discussion of the quarry includes:
But earlier, (immediately preceding, in fact), I mentioned the assumptions that go along with associations of material when they are argued to be disparate. Here’s that sentence above in context:
I’ve perhaps garbled this, as Darren asserted. The last sentence could be a lot clearer, although I presume that Matt has understood it well enough to respond to it specifically.
I am talking about multi-taxic assemblages, as well as the events that cause specimens to become jumbled. The assumption that this forms a monochthonous (single taxon) assemblage is presumed from the outset, while the size differential based first on one taxon for one element, then on another for both. Yet that size differential is not used on the former compared specimen (Giraffatitan brancai), and this is peculiar.
First, I will assume that in referencing Rapetosaurus krausei, the authors are referring to the published skeleton; this is problematic as this skeleton is a juvenile, and resolves nothing about the relative scale of the ilium to the scapula in Brontomerus mcintoshi.
Second, the ilium is much shorter than the scapula in several titanosauriform sauropods: the ilium is nearly 75% the length of the scapula in Giraffatitan brancai as well, if you prefer); it is shorter in some other titanosaurs (in Isisaurus colberti — which both Matt and I have reconstructed in this region similarly — the ilium is shorter [I have it around 90%, Matt’s is closer to 80%]). Outside of Titanosauriformes, Camarasaurus supremus has it subequal, as do diplodocids.
This difference among sauropods around Brontomerus should indicate the data is ambiguous, as it may be at the least variable among taxa without the level of restriction implied in the quoted statement from the paper. My assertion followed that association and non-overlap (raising red flags) with a phylogenetic inference that cannot discern between “short” or “long” ilium (relative to the scapula) made assumptions of the number of individuals problematic.
Thus I assert that Matt did not understand my question.
February 27, 2011 at 1:22 pm
Against my better judgement, I’ll bite. Jaime wrote:
This may be true, as far as it goes. Because it never occurred to me that anything other than diagnosability could serve as the criterion for taxon separation. Has anything else been seriously proposed? Are you proposing something else? What?
On the recognition of multiple individuals in the Hotel Mesa quarry. First of all, the scapula is THREE TIMES as big as would be expected in the animal that the holotype ilium was part of. Even if the proportions followed G. brancai rather than Rapetosaurus (which is perfectly possible), the scap is 2.25 times as big as expected. There is no way they are from the same individual.
On the so-called “assumption” that the ilium and scapula (and indeed the other elements) represent the same taxon. Jaime, when you make statements like “The assumption that this forms a monochthonous (single taxon) assemblage is presumed from the outset”, that’s the kind of thing that makes Darren wonder whether you’ve read the paper. What we actually is as follows:
So we note the possibility of two OR MORE taxa in the quarry, note that it is more conservative to assume only one, survey precedent of mixed-age groups of sauropods in the literature, explain that the diagnosis is made solely on the holotype and the the referrals are tentative, and express a hope that future work will confirm OR REFUTE the referral.
I am really having trouble understanding how this is causing you problems. Please explain, briefly and clearly, which part of this you don’t like.
February 28, 2011 at 8:26 pm
Question from the back: Do paleontologists have to pick a single element as the holotype when diagnosing a new taxon? I ask because of the Falcarius braincase. Why erect a new taxon based on a braincase when you’ve got an entire skeleton? Is it because it’s a bonebed situation?
I should probably know this already. :-(
February 28, 2011 at 9:21 pm
Do paleontologists have to pick a single element as the holotype when diagnosing a new taxon?
Not usually. Ideally, a holotype consists of material that clearly belongs to just one individual animal. That can be anything from a single bone up to a complete skeleton. Where taxa are known from disarticulated elements from a bonebed, it’s usually impossible to tell what goes with what (there are bonebeds that preserve articulated skeletons; I’m not talking about those), so whoever is doing the describing has to pick one element–hopefully the most informative–to be the holotype, and refer everything else.
We know the complete skeleton of Falcarius, but only because all of the bits are known from the bonebed. AFAIK, there are no articulated skeletons belonging to distinct individuals.
March 1, 2011 at 1:27 am
[…] remember from the Clearing the Air post that Jim Kirkland, who excavated the ilium, felt that we’d got the two smaller fragments […]
March 1, 2011 at 8:28 pm
Good arguments… but here goes another criticism for you to deal with (:)):
Why do you present a sauropodocentric drawing with Brontomerus playing football with some unfortunate theropod? Most mammals and birds have cranially elongate ilia and do not go around disrespectfully scoring goals with smaller animals!!
Cheers
March 1, 2011 at 10:15 pm
Why do you present a sauropodocentric drawing with Brontomerus playing football with some unfortunate theropod?
Because there are FAR too many life restorations that show theropods committing crimes against herbivores, and far too few that show them getting their just desserts.
Most mammals and birds have cranially elongate ilia and do not go around disrespectfully scoring goals with smaller animals!!
Are you accusing Brontomerus of being the world’s first soccer hooligan?
Also: I have known many birds who would disrespectfully attempt to score goals by kicking larger animals, myself included.
March 2, 2011 at 1:36 pm
Fair points. I hope Brontomerus was not a Mesozoic Messi, and will not judge his morality yet (I will not make accusations for those lawyers among the numbers of Brontomerus fans may start a court case against me).
> Also: I have known many birds who would disrespectfully attempt to score goals by kicking larger animals, myself included.
But, in this case, are you talking about goal kicks (a kick which makes the kicked thing to fly forwards) or a something more similar to a karate kick, where the leg extends to become in line with the direction of the kick? or a retracting kick (would be a backwards pass)?
March 2, 2011 at 5:09 pm
But, in this case, are you talking about goal kicks (a kick which makes the kicked thing to fly forwards)
In all cases, whether being flogged by a chicken or a duck or dive-bombed by some pissed-off passerine, the effect has been to make the kicked thing (i.e., me) flee forward, so yes, I’d call them goal kicks.
March 4, 2011 at 5:03 pm
This may be a day late and a dollar short, but if anyone ever has a question about the value of blog posts to “real” science I’ll be referring them to this post. It’s a brilliant example of the sort of discussion that occurs outside of the literature but can strongly inform subsequent publications.
I love it.
March 5, 2011 at 8:10 am
Mike:
Clearly, succinctly, if I were to actually take issue with this paper it would be on THREE things, and only three things. I’ve mentioned them before:
1. Stratigraphic taxonomy. Really, any taxonomic issue that is as poorly handled as in the paper. I don’t care IF you put in a sentence discussing it, you handled it poorly in the diagnosis and later on the arbitrary disregard for the taxonomic issue. You don’t get to make that decision.
2. Selection of a holotype from a juvenile. I have almost as much disdain for this practice as I have for selection of teeth as holotypes (I’ve had this discussion with paleo-selachian researchers — imagine how that discussion must go). I am still waiting on a defense of this.
3. Using partial, often broken material, and assuming features not preserved as part of the diagnostic apomorphies establishing the taxon: proportions, shapes, orientations — I will leave you to look at the five features diagnosing the ilium and let you figure out what I’m talking about.
March 5, 2011 at 10:31 am
Jaime:
Regarding the stratigraphy, you can consider your point made. We still stand by how we handled it in the paper.
We have a post in the works on how sauropod bones change through ontogeny and whether that affects the ilium, at least for an animal that is as already as big as the Brontomerus holotype (preview: as far as the available data show, it doesn’t). We’re doing this post because isometry and allometry in sauropod development is inherently interesting and worthy of discussion, not because you think we owe you a defense. As I said about a zillion comments ago, we’ve already done our homework on this, and if you think we’re in error, it’s on you to bring some evidence to show that that’s the case; your “disdain” is irrelevant.
Regarding your third point, I’m sorry, I have no idea what you’re talking about. Earlier this week you wrote, “Mike, awesome explanation. Pretty clear, then atn this point, and I appreciate you taking the time responding to my emailed questions in this highly graphic and fundamental way. At this point, you’ve convinced me that the postacetabular ala is as you illustrate in the paper. Thank you.” What changed between then and now? What specific characters do you find unconvincing?
May 17, 2018 at 8:40 pm
[…] they get poached or vandalized. Yes, that is a big problem – the Brontomerus type quarry was partially poached before the bones we have now were recovered, and vandalism at public fossil sites in Utah made the […]