…Continues.
Hot on the heels of the description of a juvenile Tarbosaurus bataar (MPC-D 107/7), Fowler et al. (2011) have produced a piece that seeks to reclaim some sanity when it comes to descriptions of apparently basal and/or juvenile tyrannosaurids as new taxa. They weigh in on Alioramus altai (along with Alioramus remotus by extension, being nearly the same size), MPC-D 107/7, and Raptorex kriegsteini. The latter in particular, which we’ve discussed before (and before that) in which even their use of scare quotes around the name in the paper’s title indicates their disdain for the nomenclature. In the end, they argue that LH PV18, the holotype of Raptorex kriegsteini, is a juvenile tyrannosaurid, and probably Tarbosaurus bataar and also from the Late Cretaceous of Mongolia. The case is interesting not because of what their conclusions are (which are predictable; Tsuihiji et al. [2011] nearly said the same thing) but because of how they got to them.
Juvenile tyrannosaurids. A, MPC-D 107/7 (Tarbosaurus bataar), original (1) and interpretive drawing (2); C, IVPP V4878, holotype of Shanshanosaurus houyanshanensis, taken from Wikipedia; C, LH PV18, holotype of Raptorex kriegsteini, from Sereno et al., 2009.
Fowler et al. particularly take issue with three things about that tyrannosaurid specimen, it’s provenance, ontogenetic age, and its morphology. The first is used to argue that the material is from other tyrannosaurid (as opposed to tyrannosauroid) bearing strata, the second to affirm the material is that of a juvenile, and the third that the so-called autapomorphic features are not useful in this case.
First, they reject the utility of the presence of pelycepod (bivalves) and a fish vertebra used to imply the fossil is from the Early Cretaceous. The fish vertebra, they note, appears very similar to an ellimmichthyiform clupeomorph fish, which are relatively deep-bodied and ventrally armored oddities, though Sereno et al. (2009) had originally inferred the vertebra to be of a Lycoptera, a key denizen of the Jehol Group formations to which they suggested LH PV18 derived from. But while Fowler et al. are likely correct in dismissing the bivalve and fish data, they ignore Sereno et al.’s argument in regards to sedimentology, first by using the doubtful association of Sereno et al.’s suggestions and then by taking their own spin of the likely distribution of that material. Ellimmichthyiform fish, as noted by the authors themselves, span from the Early Cretaceous to the Eocene, and thus their presence would not be restrictive to the Upper Cretaceous, or to any particular formation.
But in ignoring the sedimentology of the material in which the specimen was recovered, which was available to Sereno et al. for study, they passed by an opportunity to test their assertions regarding which possible formations the specimen could be from. In their supporting online material, Sereno et al. note that the sediment of the matrix of the specimen is a green, tuffaceous sandstone, a mixture of fine sands and even finer ashes that form from volcanics. They also posited that many Upper Cretaceous formations that preserved large-bodied tyrannosaurs lack this type of sediment; specifically, they excluded the Cenomanian Iren Dabasu Formation, and this sedimentology prevents the material from being from the Nemegt Formation of Mongolia, or the Udurchukan, Subashi or Wulanshuhai Formations of China, all formations from which tyrannosaurids are known in Asia in the Campanian and Maastrichtian. This material is common in the lower Jehol Group, particularly the Yixian Formation, and especially the Lujiatun beds which are helpful in that they preserve material commonly as three-dimensional and articulated specimens. But this type of sediment is unknown from those formations, which are generally mudstones in fluviatile channel facies, not unlike that of the Dinosaur Park Formation.
So, while Fowler et al. make useful their doubt, they do not actually dismiss Sereno et al.’s argument for the possible locality from which LH PV18 was recovered. Their seemingly strongest data point, rather, is a note on a conversation one of the authors (Pete Larson) had with one of Sereno et al.’s authors (Henry Kriegstein) who bought the specimen from a private broker, and with that broker about how the material was originally offered for sale as being from Mongolia. Perhaps this type of exchange is useful anecdotally, but I have my doubts. Not because I distrust either of the people involved, but because I doubt any amount of word-of-mouth from retailers of fossils who chose not to collect detailed geographic and stratigraphic data upon collection, and I am surprised that Fowler et al. are not more critical of this than using it in support of their premise that LH PV18 cannot derive from the Early Cretaceous.
Second, and most problematically, Fowler et al. throw a monkey-wrench into the age-assessment criteria by noting several choice pieces of information. Sereno et al. over-estimate their age, the authors argue, by using as their baseline attachment of vertebral neural arches to their centra and partial closure of the sutures, but these vertebrae are described as “attached” but also in parts slightly dissarticulated. A similar, if not identical condition is present in IVPP V4878, holotype of Shanshanosaurus huoyanshanensis (Dong, 1977) where the vertebrae are sometimes disassociated or fused, with articulated but open sutures, etc.
Presacral vertebrae of IVPP V4878, holotype of Shanshanosaurus huoyanshanensis Dong, 1977 (after Currie and Dong, 2000). Note variabkle articulation and closure of sutures. A-F represent anterior cervicals, G-J represent posterior cervicals transitioning into anterior dorsals, and K-O mid- to posterior dorsals. Obliteration of sutures only occurs in the cervicals and anterior dorsals (although this varies), while this is partial more posteriorly). Four additional anterior dorsals, preserved in sequence, are known but not shown, and they also indicate partial closure.
The vertebrae are undescribed for MPC-D 107/7, resulting difficulty assessing the arguments of either Sereno et al. or Fowler et al. independently when comparing to a “confirmed” juvenile Tarbosaurus bataar. Yet MPC-D 107/7 remains particularly key here; without it, I doubt Fowler et al. would be so easily swayed to assuming LH PV18 derives from the Late Cretaceous of Mongolia, and is therefore a Tarbosaurus or whatever. Sereno et al. sectioned the limb bones of LH PV18, and with it argued that two apparent LAGs represented samples of age. LAG (lines of arrested growth) counting is actually more complicated than it seems. These are zones of bone formation that occur in the cortex of growing bone, and build around older layers; while the newer cortical bone beneath the surface layer (made of lamellar bone) is being placed down, bone in the medullary cavity is being eroded, or absorbed, and then rebuilt by secondary processes and refilling the space, thereby obliterating LAGs.
So as growth continues and new zones of bone tissue are placed down, older bone is eventually lost. The first ring of bone growth is usually being eroded by the time the animal hatches, and then this continues throughout life. Annual growth can increase, or decrease, and the relative thickness of the growth zones (LAGs) result in clues as to how fast the animal is growing, but even more so, concentrations of osteoblasts (the cells that actually grow bone) increase when bone is more vascular and sexual maturity is reached, at which point, bone growth typically slows (resulting in relatively thinner lines). Accounting for the lost rings, and thus lost years of measure, in bones can be tricky, and is based largely on having a relative sample of growth series to project a bsaeline from (usually a hatchling) and so forth through to the largest individuals; this technique, called back-calculation, requires not only estimating the rate of deposition of the innermost rings, but projecting this data onto an expectation of rapid versus slow growth. If the animal is precocial, say, rapid growth early on as the animal puts on the pounds should indicate thick lines initially, followed by thinner lines later on as maturity increases, and there is usually no sigmoid curve; when these lines are relatively the same, then growth is steady; when the lines increase in thickness, the growth is increasing.
Hypothesized timing of sexual maturity in North American tyrannosaurs. From Erickson et al. (2010), after Erickson et al. (2004) and Schweitzer et al. (2005).
Tyrannosaurs show a sigmoid curve during growth (Erickson et al., 2004), showing slow growth up to about 10yo, followed by steadily or rapidly increasing growth. As osteoblasts increase in the outer layers, the animal nears sexual maturity. Bone growth only stops when the periosteum forms around the cortex, capping off new bone growth. Both LH PV18 and MPC-D 107/7 have had their long bones sectioned for histological slides, producing valuable information. However, the authors in Fowler et al. and Sereno et al. appear to differ on some fundamentals of how old the same material is. Fowler et al. note that Sereno et al. had inferred thickness of the outermost LAG to the lamellar growth band was the result of rapid growth and deposition, and thus used the thickness between LAGs 2 and 3 to estimate internally missing LAGs. If Sereno et al.’s argument is true, LH PV18 would have undergone an unusual rapid spurt as it reached maturity, rather than slowing down, and this is highly unusual. The better explanation is that the thin band between LAG 2 and 3 is indicative of unusually slow growth during the early “slow growth” period, and thus may have been indicative of lean/hard times in the year following deposition of LAG 1. Thus Fowler et al. correctly infer that relative thickness of some LAGs need to be seen broadly, rather than narrowly.
Histological section of the femur of LH PV18, holotype of Raptorex kriegsteini Sereno et al. (2009). Blue bars represent bands of bone tissue, where 1-3 represent thicknesses bewteen LAGs according to Fowler et al. (2011); each LAG is numbered for the base of the line, while the final growth band hasn’t finished depositing, but is relatively close it seems to a fourth LAG. “?” represents the base of bone below LAG 1, and represents the portions of a remodelling zone. “s” indicates the lamellar surface bone, and “mc” the medullary cavity.
Oddly enough, both papers propose the same maximum age of 6yo, while Fowler et al. err towards 3yo at the minimum, while Sereno et al. close in on 6yo. I’m tending to think Fowler et al. is correct on this one.
Third, there’s the issue of morphology. Sereno et al. distinguished LH PV18 from other tyrannosauroids by the following features:
Basal tyrannosauroid with a narrow accessory pneumatic fossa within the antorbital fossa dorsal to the maxillary fenestra, jugal suborbital ramus of particularly narrow depth (transverse width approximately 60% of vertical depth), and absence of a vertical crest on the iliac blade dorsal to the acetabulum.
[Sereno et al., 2009:pg.422:ref.15.]
However, Tsuihiji et al. (2011) revised this, noting in turn:
[T]wo of the characteristics that Sereno et al. (2009) proposed as diagnostic of R. kriegsteini, a shallow suborbital part of the jugal and presence of an accessory pneumatic fossa dorsal to the maxillary fenestra within the antorbital fossa, are also observed in MPC-D 107/7[.]
[Tsuihiji et al., 2011:pg.515.]
This left the issue of the absence of a vertical iliac crest. Fowler et al. note that Pete Larson observed a vertical iliac crest on the ilium, which would in turn remove the last morphological barrier cited by Sereno et al. for distinguishing Raptorex kriegsteini. They also refer to the cranial features noted by Tsuihiji et al. as “two minor skull characters,” and that has me perplexed. They must think that there is relative value to morphology when performing analysis, characters or suites of them that are “better” than others. If we were talking about features that are prone to convergence, or allometric scaling issues, or features relating to ecology that might crop up in different similarly habituated species, then we could, but no such assessment is made, just a casual dismissal (much as scare quotes around the name Raptorex peppers the paper, or the use of specimen numbers followed by “described as ” appellations when dealing with Alioramus altai and Shanshanosaurus huoyanshanensis. (I am actually surprised those names weren’t in scare quotes: Tsuihiji et al. all but nailed the latter as a juvenile Tarbosaurus bataar.)
The ilium deserves some note. If Pete Larson saw what I see in the photos above, then I suspect that while he feels he may be correct in arguing what appears to be a node on the surface of the ilium above the supracetabular crest is a vertical crest. However, that is not what I see; instead, it appears to be a divot of sorts, a defect owing to reconstruction of the material. The photo shows the original material, sans the skull, including clearly-colored plaster additions. This shows the ilium was reconstructed and broken, including around the area in which the “crest” lies. Tsuihiji et al. (2011) appear to affirm the lack of existence of this “crest,” so the identification seems ambiguous.
Tsuihiji et al. further note that while they think the material warrants further scrutiny on its age (which Fowler et al. appear to nail), some peculiarities prevent them from lumping the species in with Tarbosaurus bataar. This includes a large surangular foramen (see below), and the much taller anteroventral process of the vertical ramus of the lachrymal, nearly fully 1/3 the lachrymal height (as in Alioramus altai, below). A further differentiation is that unlike other juvenile tyrannosaurids, the maxillary fenestra is nearly as tall as it is long, and the promaxillary fenestra is obscured by the posterior extent of the anterior margin of the external antorbital fenestra; the former is quite usually much longer than tall, and the latter visible in smaller (IVPP V4878), equally-sized (MPC-D 107/7) and larger (MPC-D 100/1844) specimens. Partly due to this, as to uncertaintly regarding its age, Tsuihiji et al. do not think that LH PV18 is a juvenile Tarbosaurus bataar, although it may be a juvenile of another taxon.
Selected portions of juvenile tyrannosaurid skulls. All scale bars represent 5 cm, and so all skulls are to scale. LH PV18 is the holotype of Raptorex kriegsteini (after Sereno et al., 2009); MPC-D 107/7 is after Tsuihiji et al. (2011); IVPP V4878 is the holotype of Shanshanosaurus huoyanshanensis (after Currie and Dong, 1999); MPC-D 100/1844 is the holotype of Alioramus altai (after Brusatte et al., 2009).
Fowler et al. (2011) demonstrate with a strong series of arguments that LH PV18 is truly, actually a juvenile, rebutting Sereno et al. (2009)’s conclusion to the contrary. However, they seem more willing to also conclude that Raptorex kriegsteini is likely a juvenile with “affinities” to Tarbosaurus, despite the lack of any relation to Nemegt-equivalent beds in northeastern China. If Sereno et al. (2009) are correct (and they may not be) that LH PV18 derives from the Lower Cretaceous, this would extend what is essentially a Cenomanian-Maastrichtian clade clear through to the Barremian, and while such ghost lineages are not unexpected or necessarily wrong, they bear greater scrutiny for their extremes.
Despite this, Fowler et al. follow Tsuihiji et al. (2011) in their treatment of the specimen, albeit more along the lines of Tarbosaurus-y, but miss some of the finer details in the latter work. Certainly, the actual morphology is peculiar and not linear with older specimens attributed to Tarbosaurus bataar from the Nemegt-equivalent beds of China and Mongolia: The maxilla in youngest specimens (e.g., IVPP V4878) is shallow, triangular, and has a straight leading anterodorsal edge; in older specimens, the maxilla becomes more rounded on the anterodorsal edge, the depth of the maxilla below the antorbital fossa increases; tooth positions do not change number despite increasing size (unlike albertosaurine tyrannosaurids), and the maxillary fenestra changes from a shallow oval into a tall sub-triangular shape. In the specimens above, we see at the bottom the maxilla of MPC-D 100/1844, holotype of Alioramus altai (Brusatte et al., 2009), which despite its much larger size, does not resemble the maxillae of subadult tyrannosaurines, and is even relatively shallower than in juvenile tyrannosaurines, while the sub-antorbital depth of the maxilla is shallow, and teeth increase in number. LH PV18 agrees with all of these features as a juvenile Tarbosaurus, but this has me thinking that instead, it’s based more parsimoniously on juvenile tyrannosaurines. We simply lack the comparative material for Tyrannosaurus rex, and all this dismissal of taxa makes for applying relative juveniles of different taxa rather difficult.
I will post shortly on what I actually think of the taxonomic issues involved in the recent spate of juvenile-based tyrannosaur species being named of late. I’ve refrained in large part out of respect, though to be fair in my recent criticisms of some work, I will not hold back on others’. Does this mean I disagree with Sereno et al. on the subject of Raptorex, and agree with Fowler et al.? Well, yes and no.
Brusatte, S. L., Carr, T. D., Erickson, G. M., Bever, G. S. & Norell, M. A. 2009. A long-snouted, multihorned tyrannosaurid from the Late Cretaceous of Mongolia. Proceedings of the National Academy of Sciences, Philadelphia 106(41):17261-17266.
Currie, P. J. & Dong Z.-m. 2001. New information on Shanshanosaurus huoyanshanesis, a juvenile tyrannosaurid (Theropoda, Dinosauria) from the Late Cretaceous of China. Canadian Journal of Earth Sciences — Revue canadienne de sciences de la Terra 38(12):1729–1737.
Dong Z.-m. 1977. [On the dinosaurian remains from Turpan, Xinjiang.] Vertebrata PalAsiatica 15:59–66. [in Chinese]
Erickson, G. M., Makovicky, P. J., Currie, P. J., Norell, M. A., Yerby, S. A. & Brochu, C. A. 2004. Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs. Nature 430:772-775.
Fowler, D. W., Woodward, H.N., Freedman, E.A., Larson, P. L. & Horner, J. R. 2011. Reanalysis of “Raptorex kriegsteini“: A juvenile tyrannosaurid dinosaur from Mongolia. PLoS ONE 6(6):e21376.
Holtz, T. R., Jr. 2004. Tyrannosauroidea. pp. 111-136 in Weishampel, Dodson & Osmólska (eds.) The Dinosauria, second edition. University of California Press (Berkeley).
Newbrey, M. G., Murray, A. M., Brinkman, D. B., Wilson, M. V. H. & Neuman, A. G. 2010. A new articulated freshwater fish (Clupeomorpha, Ellimmichthyiformes) from the Horseshoe Canyon Formation, Maastrichtian, of Alberta, Canada. Canadian Journal of Earth Sciences — Revue canadienne de sciences de la Terre 47(9):1183-1196.
Sereno, P. C., Tan L., Brusatte, S. L., Kriegstein, H. J., Zhao X.-j. & Cloward, K. 2009. Tyrannosaurid skeletal design first evolved at small body size. Science 326:418-422.
Tsuihiji T., Watabe M., Tsogtbaatar K., Tsubamoto T., Barsbold R., Suzuki S., Lee, A. H., Ridgely, R. C., Kawahara Y. & Witmer, L. M. 2011. Cranial osteology of a juvenile specimen of Tarbosaurus bataar (Theropoda, Tyrannosauridae) from the Nemegt Formation (Upper Cretaceous) of Bugin Tsav, Mongolia. Journal of Vertebrate Paleontology 31(3):497-517.
Jaime A. Headden
The Bite Stuff 
If “Raptorex” turns out to be some sort of juvenile Tyrannosaurid then would that imply that the there was a radiation amongst Tyrannosaurs in the Lower Cretaceous? Would it also imply that the Tyrannosaurids appeared much earlier then originally thought?
If only we had an adult specimen!
Well, the stratigraphy issue aside, both Tsuihiji et al. and Fowler et al. appear to firmly support it is a juvenile. Of what, however, is the question. If Tsuihiji et al. are correct but Fowler et al. are not, then we have three large-bodied, megatonner tyrannosaurids (Tarbosaurus Zhuchengtyrannus, and Raptorex-adult). It’s very difficult, however, to accurately assess the affinities of the juvenile specimen, so in many senses it is a “dubious name.”
Stratigraphy extra: we put in a sentence about the presence of articulated specimens in the Iren Dabasu. On the sedimentology: no slides or photos are provided in the Sereno et al. MS, so we cannot assess this data and it should not be admitted as it could not be assessed by reviewers. Given the lack of precision in ID of the fish vertebra (it is obviously not a Lycoptera), I wonder whether the sedimentological assessment has any weight either. Anyway, further evidence (W4TP) suggests the specimen is from Mongolia. There is no evidence that links the specimen to the Early Cretaceous. We included pers comms from the seller to demonstrate that the specimen was never represented as having come from china. This was entirely inferred (by the authors) from the fossil. Kriegstein confirmed this in a pers comm.
The point of our paper is to show that none of the claims of the original description are supported by the published data. This is what happens when you work with stolen specimens.We aren’t doing a morphological / taxonomic analysis. We are mainly concerned with the histology and fish vert.
Pete Larson saw the original material, and provided photos. We couldn’t publish these of course, but the observations are sound. You should see the dorsals and caudals; some of the neural spines are hanging off. Anyway, our point here was that neurocentral fusion has not been studied and should nto be used as (strong) evidence. Histology is soli. histologically, this critter is a juvie. very much so.
On growth: like many people reading the erickson paper, you need to learn how to read a graph, and what happens when you plot a cube. the sigmoidal shape is because this is a graph of a cube (ie. mass). growth is most rapid when the animal is youngest. look at the numbers. there is no growth spurt.
I admit the argument about the finding of a Late Cretaceous tuff is weak, as I’m sure there is one — somewhere — but the absence of finding one as an alternative weakens the dismissal nonetheless. Your argument was dismissive of the Lujiatun beds on the sole basis of suggesting the Iren Dabasu sediments MIGHT be nice to look at (no positive evidence involved) while allocating the vertebra to a group of fish that spans the Cretaceous from the Barremian up to the Maastrichtian, where the only taxon you positively compared to was from the Horseshoe Canyon Formation, as if that means anything about restricting it from the Yixian Formation. It also does not matter if taxa from the Iren Dabasu might be similar — so are taxa from the Nemegt, and the sediment is CERTAINLY not from there — only that the sedimentology precludes the obvious Camp-Maas choices. I never said it wasn’t from the Late Cretaceous, but if you can find me a sedimentology that matches, I’d be happy to retract my statements.
On the specimen: I do not doubt that the specimen is a very, very small and young animal, and neither do Tsuihiji et al., who had previously claimed it to be about as young as their 2-3yo specimen. It should be noted that I agreed with the main number of your conclusions, just not all of them; that taxonomic conclusions, such as they were, were unfounded because of provenance doubt while summarily dismissing Tsuihiji et al.’s conclusions; that Tsuihiji et al. in fact already argued that the specimen was a very young juvenile but that there was doubt as to whether you could lump it in with MPC-D 107/7 as “Tarbosaurus bataar.” I wish you had included the photos, as the material had already been published on, but as your note in the acknowledgments state, if you had full access to the material via Paul Sereno, why couldn’t you produce the photos? I find the original photographic material of the specimen inadequate, and would have thought you’d welcome the space and allowance PLoS ONE gave you to set the material quality straight, but this wasn’t so.
I’ll admit on the matter of growth scaling that I was reading overall size rather than mass, but I wasn’t confusing linear measure with mass, either.
There is no evidence that the specimen comes from China. Sereno et al do not justify their Lycoptera ID (which is definitely wrong). The specimen might be from China, or might be from Mongolia (based on more info: almost certainly). Again, our point is that this is not known; in the original description, the authors go so far as to state coordinates for the locality, and certainly do not make clear in the main MS that the locality is only inferred from (incorrectly IDd) fossils.
The sedimentology isn’t figured so it isn’t data. You can;t hinge the entire “not Nemegt” argument on a half sentence describing unfigured sediment, especially given that the attempts to ID other associated materials are very obviously incorrect. Can you assess whether or not the sediment is truly “tuffaceous” (etc)? could the reviewers? no.
The onus is on the authors to provide evidence (not just words) of original locality. We state that the locality data is equivocal.
And on photos: we aren;t doing a taxonomic / morphologic review of the specimen (someone else might be). we were reviewing the histology and the strat data. We do state that, given the amount of time represented by the Asian sections, then it would be expected to see more definable morphologies than just T. bataar. It is possible the small differences seen between LH PV18 and MPC-D 107/7 are taxonomic, but we really don’t have a handle on ontogenetic and individual variation in tyrannosaurs, and we will (likely) never know the precise strat position of LH PV18 (relative to MPC-D 107/7). These things are important. Our work on trikes is showing how slight variations in many factors can define/explain individual variation.
Basically, specimens with none of the essential data should not be published, especially as holotypes; they are not useful, and only hinder progress in the future.
If the specimen derives from Iren Dabasu, say, or the Subashi Formation, then indeed, it would come from China. But similarly, there is no evidence the specimen comes from Mongolia, save that it was originally put up for sale as if it were coming from there. Absence of this documentation means that there is doubt both ways. Do I commend Sereno for going forward and describing the specimen without provenance data? No. But he did have some corollary evidence that suggested there might be some indicators, even though on the matter of the fish vert, he was wrong. But even the fish vert does not contradict the impression, also based on the type of matrix the material was found in, that the specimen came from the Early Cretaceous. I would have preferred a much more substantive treatment of possible locations based on known tuffs from central Asia, the likeliest locales, but such was not the case. Despite Sereno et al. “not figur[ing]” the sedimentology, it would have less apparent weight than the verbal statement without support that the specimen “probably” came from Mongolia? And who the hell cares? Sediments in northeastern China (the Amur region in Heilongjiang, the Subashi, regions of the Inner Gobi, where the former two are located north and just to the west of Liaoning) are equivalent to those that produce known large tyrannosaurids in Mongolia, as well as those that predate said sediments.
Denver, did your reviewers do your work for you to make sure you had not committed errors? It is not the reviewers’ jobs to do their submitter’s work over again, but to either assess the quality of the work overall, make suggestions, and offer their personal or professional verdict (and in some cases, try to prevent the paper from being published). Or, if you take the tact of some, to backslap their colleagues when the reviewers are friends with a conflict of interest in making sure the work is “reviewed” correctly. Despite this, the work stands on its own, and I make no recriminations against people who did not write the piece. Instead, the work, and anything critical of it, can only be assessed by the data that is presented. Saying that someone saw a thing, has photos but does not show it, argues the material is tuffaceous if that might be doubted doesn’t cut it. Citing opinion, or talking about non-demonstrated things, doesn’t help the discussion either way.
I do agree that specimens without provenance or other implicit morphological detail are necessary, but in some cases, even had Sereno et al. NOT sectioned the limb bones (a destructive process, on a holotype no less) to try to assess the age (and provide you with your biggest bullet against his argument), the material is useful enough to describe. Do I think it should, or be made into holotypes? A broad reading of what I’ve written on this blog tells me that the only goal for our work is as-complete-as-possible, and no less should do. This should go for everyone. Holotypes even more so. I do NOT agree, however, that juveniles should not form the basis of types until firm data on the general and the specific for the clades in question can demonstrate that the value of a juvenile or an expressed feature is or is not useful for taxonomy.
“Denver, did your reviewers do your work for you to make sure you had not committed errors?”
Well, although I’m still only starting out, I do have actual experience in publishing research and have peer reviewed others’ work.
It is the reviewers job to assess the data and conclusions. To some extent you have to take the authors’ word for something; and in this case (main MS) the authors state that the specimen WAS found in china, and go so far as to give coordinates. I can understand that the editors and reviewers might have missed the fact that this is only inferred, because it is buried only in the supp info. I suspect that this paper was not reviewed by histologists or stratigraphers, yet the two primary arguments made in the paper depend upon these two areas being correct: the morphology is secondary. If the provenance is essential to the argument, then the evidence needs to be presented.
Currently (soon to change) the only evidence for any provenance is a Mongolian origin given at sale. There is no evidence whatsoever the specimen comes from China, or anywhere else. I do not accept the sedimentological (half sentence, because I suspect it is unreliable, as was all the other strat data presented. if we get some thin sections or photos of the sediment, maybe that view will change, but right now it isn;t admissable evidence.
“Citing opinion, or talking about non-demonstrated things, doesn’t help the discussion either way.”
which is what the sedimentological statement is: opinion. no evidence has been presented.
Holotypes: In theory, yes, juvies could be holotypes, but given that juvies retain all sorts of ancestral character states, they prove to be nearly impossible to use. If you have the strat data for a juvie, then eventually you may find an adult form the same stratum, and then you can compare, but if you don;t have that data, they’re useless. If you think that a very immature specimen can be a holotype, then maybe you can point out what the autapomorphies of Raptorex are without reference to MPC-D 107/7. Even with MPC-D 107/7 you’re left with a couple of characters that may or may not be individual variation. The analysis of MPC-D 107/7 shows that juveniles scored in a cladistic analysis come out much mroe basal than adults of the same taxon: juvies disrupt cladistic analysis. How much homoplasy do you think might be due to the immaturity of the holotypes?
You are not alone in a weak understanding of the extent of morphological change through ontogeny, but we are actually working on figuring this out.
Denver, you wrote: “Well, although I’m still only starting out, I do have actual experience in publishing research and have peer reviewed others’ work.”
What I am getting at is that it is not the reviewer’s job to write your paper, or rework your stuff. Sometimes, the reviewer will have only an ancillary interest in the subject matter at hand. I have asked several workers who have actually studied or publicly commented on studying, the work at hand when asking them to review my mss. Most of the time, they come back with helpful comments that help me approach the topic in a different angle, but even when they comment that they stand by earlier work, I know they at least read it, understood it, and understand how my approach worked, even if they disagree. Glaring errors are noted and emmended. This doesn’t include opinions other than making sure I cite some source for that crap. Which leads me to:
“which is what the sedimentological statement is: opinion. no evidence has been presented.”
Despite this, you cited unpublished perspectives from Pete Larson on the subject of observing the specimen at hand, and used photos you saw but could not reveal to make comments. I cannot check those comments, because you provided no data. This is, in my opinion, the worst part of the paper. I care not that opinions are made, but only that the argument to arrive at a conclusion follows a logical and observable tract. Your disagreement with my comment about the vertical crest of the ilium is based on those photos and what Pete Larson said, but you cannot or will not shore that disagreement up, leaving the published record (including Tsuihiji et al.‘s apparent examination of the material) standing as a support for Sereno et al. while you disagree. Thus, the concensus is that the ridge does not exist, based on the published work. The only thing I could think of would be that the comment should have NOT been included in the paper if it could not be backed up IN the paper. Aren’t we striving for exemplary work, and the best way to get any conclusion? To show your work, shouldn’t you have to show it?
Oh and finally, histology needed to be performed, despite this being a holotype as it si the only way to assess maturity (another main point in our paper that you somehow have missed). Cutting limb bones is technically “destructive” but if done correctly, you wouldn’t be able to tell the difference as the removed part is cast, painted, and reinserted to look like the original. if you doubt this, we had one researcher in collections who couldn’t tell the difference, and thought we had two identical bones where one was a cast. I actually wish we published a few photos of the process to demonstrate it. maybe I will put some up on our facebook page.
Histology and strat data is as essential in a description as cladistic analysis. In fact, I would argue more essential, since cladistic analysis can be conducted by other people using the description. The 19th century approach of just describing morphology and assuming it is adult is out of date. if you don;t have limb bones to section, then yeah, you need some caution but it is better to know the limits of your data, than to overinterpret it.
Denver, Schott et al. in their description of a Stegoceras validum ontogenetic series, used HRCT to examine the skulls, largely because it could arrive at a histological cross-section but was not destructive to the specimen. Jack Horner was a co-author, so I can’t understand a lack of understanding of the technique. It’s broad enough to count LAGs, although I am unfamiliar with the technique’s potential resolution, i.e., can it get close enough to discern fiber orientation and osteoblast concentration. Is this a potential viable alternative?
It’s tragic that you weren’t allowed to publish further photos on a described holotype. People need to be less controlling with “their” specimens- once they’re published, they should be fair game. If you want time to write a osteology, then don’t publish your taxon in Science. You shouldn’t get to say “Here’s my new taxon, but now wait until I do the work on it.”
I sooooo agree with this.
We didn’t ask to publish pictures, and they weren’t publishable anyway: slightly oblique etc: fine for look at neural arch fusion but not ideal for publishing.
Again, our paper is not about morphology, it’s about the strat and histo data. I accept that we make a statement on the neural arch fusion that is not figured, but my note on the sedimentology stands. A forthcoming paper shows that the most liekly source is Mongolia. How that explains the alleged sedimentology is unknown. People shouldn;t be publishing on stolen specimens with no data.
HCRT is expensive, rare to access, and does not show the same level of detail as cutting bones; it’s good for some things, but not others. Besides “destructive” histological sampling is not destructive in the way you think it is. It’s actually possible that there are no actual LAGs in LH PV18, but without seeing what it would have grown into, it’s tough to call. I think you’re just arguing for arguing’s sake here: we need to know ontogenetic status in order to make a proper call on morphology, especially in holotypes. These specimen’s aren’t precious gold; they’re scintific pecimens and should be treated as such.
And don;t patronize me on publishing. I’ve done research, written and reviewed papers. You haven’t. My point about reviewers was not of my own work, but of Sereno et al 2009. It wasn;t adequately reviewed, partly because of the way the material was presented.
I’m looking forward to seeing your hypercritical assessment of the original Raptorex paper.
Denver, I only wish to comment at this point on my claim of “destructive” processes, i.e., regarding the histological sectioning of limb bones via saw. Your last two comments should deserve more time to reply to not only because of the ad hominem inherent in the last, but the sheer level of ignorance in the second to last. You know not of that which you speak of.
In the fashion of taking a saw to a limb bone, the saw cuts into material, not once but twice, and leaves a section of removed space that is greater than the slice removed because of the amount of material on either side, even if this is so very slight. This has the effect of “destroying” a portion of the material. If this were a holotype, then part of that material is lost. Let us pretend for a moment that what we are dealing with was, in fact, the London Archaeopteryx lithographica; during initial and subsequent preparation, after plates were published of its initially recovered and primary preparation were completed, it was shown to possess slight impressions of integument around the legs and belly. But these regions are missing now on the specimen, prepared away to recover the margins of bones and find hidden elements. Today, we can extrapolate using CT and MRI hidden tissues, but not always to the finest depths, but they allow us to examine the otherwise unobservable when the process to uncover them might damage the material; we also take great pains today (some of us, anyway) of careful preparation to preserve impressions because of the discoveries at Solnhofen and elsewhere in Bavaria’s lagerstaetten and because of Liaoning Province’s various sediments. Any process now that eliminates this as a matter of course is “destructive.” Even workers who engage in this sectioning of limbs consider it destructive, so while I understand your point and the effective argument, it is nonetheless a settled argument. I’ve already cited an argument toward this effect.
On the other hand, the need to recover the information leads to a second point, that it is the best way (i.e., cheapest, quickest (?), allows for personal examination without a machine, etc.) but I think that the mere fact of destruction, loss of material, the potential that the fragments of tissues recovered may not exist anywhere but at the sectioned site (making the process one that
removes from the specimen the evidence of this feature). I think we will be moving toward non-invasive techniques more and more, given the prevalence of machines that can peer into the bones for our purposes.
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Great overview of this :). Little late for a comment, but one thing on the section of the first image from Wiki Commons. This reconstruction should not be used greatly for comparing, as the uploader has a history of freehanding his skeletals, which tends to make the proportions and anatomy somewhat off. A study of the original figures would be better than using this image.
I’m unsure what you mean. My use of the skeletal reconstruction from Wikipedia has not, nor is it implied to be, a source of study. Virtually no adequate rendering of the holotype of Shanshanosaurus has been done, and I wasn’t inclined at the time to offer my own. Further, it seems you are insinuating some laziness on my part when reporting on the details of the story, as I performed no explicit analysis of my own. Lastly, I do offer original figures from the redescription of Shanshanosaurus in the image below the one you show issue with, so … what’s up?
My apologies. I was not intending to imply anything with my above comment, just inform people of the potential that the reconstruction from Wikimedia is not completely correct before they base their own analysis upon the image. Its use for illustrating the approximate material is fine, actually recommendable, however, some might take its use of illustration as the fact that it is accurate.
Completely unrelated to this topic, do you know if the image http://phylopic.org/image/f3c74352-543f-4d28-ba4a-de5bfa338ce9/ is truely yours, as it says. If it is, then did you submit it to Phylopic? I might use it as the basis for a size comparison if it is yours. If it is not, I should not use it because of potential license issues. Oh, and also if it yours, great image, finally a fully feathered close relative of Tyrannosaurus.