I Cannot Compel to Reason: Triceratops, We Done It Again


Earlier this year, Andy Farke took the opportunity of  a remodel to assess the skull of that classic of classic dinosaurs, Nedoceratops hatcheri. Formally named by Richard Swan Lull (completing a monograph that first OC Marsh had begun but uncompleted by hid death, and then resumed by John Bell Hatcher until his death), he presumed it may have been a pathological specimen, probably Triceratops (one of its species, many of which abounded at the time), owning to large irregular rather than concise fenestrae in the parietals and one of the squamosals; but he relented on the idea of its apparently unique features and coined the name Diceratops hatcheri. The name would be later found to be ironic.

(We’ll leave aside the issue of Diceratops becoming Diceratus (Mateus, 2008) as well as Nedoceratops (Ukrainsky, 2007), with the later being named, funnily enough, by an entomologist (see Ukrainsky, 2009 and Farke, 2011 for discussion).)

As I discussed in part here, it later became apparent that the specimen was particularly similar to what is now called Triceratops (again, to one of its species) and to Torosaurus (to one of its species), but researchers disagreed as to its affinities. It labored in chaos at least until the advent of phylogenetic analysis was brought to bear on ceratopsians, and Forster (1996) found it to come out into a position immediately between the two Maastrichtian ceratopsids. This made three Maastrichtian “genera” of ceratopsid, and a plethora of species sunk, leaving only prorsus and horridus in Triceratops, hatcheri in Diceratops, and latus and gladius in Torosaurus. What was a horrible complex and profusion had been drastically simplified. This would be advanced much, much later by analyses of growth and variation. Scannella & Horner (2010) disagreed with the general premises offered by past arguments and asserted that growth could account for the differences between all specimens, including all putative apomorphies. This would knock the species count down somewhat, although it is not clear to what as the authors only provided argument for “generic” synonymy, leaving the question of species synonymy to a later date (as one might imagine, I threw something of a fit about this). While humorous and exasperatingly marred by the public outrage of “We’re losing Triceratops?!” the paleo community awaited discussion of these acts and further elaboration. For example, Scannella & Horner merely asserted that specimens called Torosaurus belong to specimens called Triceratops, but that the species complexes were yet unresolved; it would be necessary to establish the species assignment of the various holotypes, as one cannot simply assert a species type is not longer typic and only a genus can be synonymized.

Here’s a secret: I think Scannella & Horner have it right — to a point [n2]. There does appear to be a single consistent lineage of ceratopsid, and its name is probably Triceratops. The issue here, as it has always been, is that the complex of species and the argument that there are in fact distinct species within Triceratops (averred by Forster, 1996, and supported by everyone since) is made in connection to this statement, but they are not mutual. One can have a clade called Triceratops and a whole mess of viable species. This occurs today among terrestrial herbivores which are closely related, especially savannah antelopes in Africa, or “subspecies” of wolves, “species” or complexes of such of varanid lizard (almost all of them called Varanus, but some whom refer to them by their “subgenera,” names that could under any other circumstance be “genera” instead), and this is just talking about well known megafaunal cases. My take on this is to treat Triceratops as a clade, and as a entity no different than Ceratopsidae. It would be stupid, if not unintelligible, for me to refer Torosaurus to be a junior subjective synonym of Ceratopsidae, in the sense the authors have done to it for Triceratops, but that is what they’ve effectively done. The problem here, then is that the authors aver some external validity to the nature of the “genus,” and the “family;” they argue as though the ranks Genus and Familia are real, viable objects. This, for many, many reasons (many laid out here and somewhat tangentially here, where I approach the ambiguous and essentially meaningless use and practice of the term “nomen dubium“) just doesn’t jive.

So, Torosaurus is Triceratops. Phylogenentically, it seems that prorsus and horridus form a complex regardless of hatcheri, and that latus is outside this, serially. This has been somewhat of a problem because generally, juveniles of taxa should tend to clade together, and they tend to share more features due simply to lacking adult characteristics to differentiate them. This works when diagnostic features tend to show up only during adulthood, or late adulthood, as Scannella & Horner argue. In some cases, it can show up earlier in ontogeny, but the authors aver that while they can segregate younger adults stages of Maastrichtian ceratopsid into two species, they choose to emplace these morphologies into a single broader category, and relegate all other potential taxa to the broader category, preserving the lesser (species). This makes things difficult again, and where I’ve had discussions with no resolution on the outcome with several of the principles in this “debate.” The issue is merely waiting for future work. This is not aided by the fact that the discussion of these taxa is in the “generic” (pardon the pun) rather than in the substantive or “specific”: Scannella & Horner eschew use of the species names prorsus or horridus in favor of Triceratops at nearly every opportunity (“prorsus” appears in the 2011 paper twice, “horridus” five times; in the 2010 paper, this is two and two, respectively, a ridiculously low count when you are talking about synonymizing taxa).

Perhaps further work, or further whining from me, might compel some sense that when you synonymize taxa, or aver they are the same, one does so in concern to the species, not the “genus.” This is especially important as increasingly new diverse taxa show up which show bizarre or divergent adult morphology, juveniles or subadults are being granted new “generic” status without quantifying ontogenetic relevance of the characters, and so forth.

Farke (2011) attempted to resolve the complex problem offered by Scannella & Horner (2010), only further complicated by the addition of a fourth Maastrichtian ceratopsid “genus” to the “Triceratopsini” complex, Eotriceratops xerinsularis (Wu et al., 2007). The taxa multiplied before our eyes. This was not counting the eventual naming of a fifth (Ojoceratops fowleri Sullivan & Lucas, 2011 from the Ojo Alamo of Formation of New Mexico (roughly equivalent with the late Maastrichtian) and a sixth (Tatankaceratops sacrisonorum Ott & Larson, 2011 from the Hell Creek of the Dakotas) — all of which I note here. While it’s been noted that the limited material (the holotype is a squamosal) of the former, bizarrely similar to the squamosal of Nedoceratops hatcheri in some respects, is geographically sundered from the Hell Creek and equivalent up north, biogeographic mapping places taxa that occur in both, including Tyrannosaurus rex in the north and south, and Alamosaurus sanjuanensis, which occurs in equivalent late Maastrichtian strata in Utah as well as New Mexico and Texas. Scannella & Horner (2011) have fired back a salvo in a sharp, precise paper, one that clearly argues that each of Farke’s reiterated diagnostic features (following some of Forster’s 1996 work) are represented as variation among the complex of specimens referred to Triceratops (as different species).

I’m beginning to suspect that much of this indicates that the faunas of the late Maastrichtian are either strongly latitudinally segregated, or homogenous, and changing at the same rate stratigraphically. This is the only way to so far explain the effect of keeping some disparate morphologies distinct, and others together. This is not to say I think the current model is wrong, or that it is right, and I will say up front I actually have no opinion. I think particular biogeographic biases may be interfering with a solution to the problem. It may be possible that all of these late Maastrichtian taxa are synonyms of some level below “Triceratopsini.” If so, it makes a distinct “Triceratopsini” clade containing them redundant, and these Triceratops-like taxa are Triceratops. This would render variation limited, individual, and pathologic, rather than specific (or “generic”). A major influence on this discussion has been the radical ontogenetic change Scannella & Horner (2010) argued for. It seems particularly strange to me that the authors should argue that this change should occur in such a limited respect, confined to merely a few species of a single “genus,” or that related but dissimilar taxa would not also show this same change. If this ontogenetic transitional series were to be plausible for a diverse range of species, yet all generally related to one another, and where one could not reasonably tell the juveniles of two closely related by distinct species apart (as was the case for a long time without the aid of biogeographic and stratigraphic models in hadrosaurs), then it would be impossible to tell three, or even four apart. It may instead be more simplistic to afford all of the taxa a single species, and ignore the whole “species referral” mess to which I bemoan, or that there may ever be distinct “genera,” but then this merely underscores the very problem of “genera,” and the utterly subjective and unscientific concept thereof.

Scannella & Horner (2011) argue (pg. 7):

Until a clearly juvenile ‘Torosaurus’ is recovered – with backwards curving postorbital horn cores, delta-shaped frill epiossifications, elongate squamosals, and a fenestrated parietal – it appears more likely that either: a) juvenile ‘Torosaurus’ were largely indistinguishable from Triceratops and differences in morphology between these two taxa only became apparent later in ontogeny, or b) ‘Torosaurus’ and Triceratops are synonymous. We favor the latter hypothesis for reasons previously discussed in detail in [Scannella & Horner (2010)].

Personally, I do not think it wise to modify the apparent taxonomy of these ceratopsians, call other arguments into question, then claim that the burden of proof is on them to prove you wrong, rather than attempting to demonstrate beyond the possibility of (a) above (the status quo) that those who’ve argued for current model should be held until proven directly wrong. As I said at the beginning, I think Scannella & Horner have it right, but this is in the generic (again, pardon the pun). I would have preferred that the authors determined a test to their argument by showing that Torosaurus latus or Nedoceratops hatcheri cannot be specifically or “generically” distinct from any category with Triceratops. And this is simply because I think all Scannella & Horner have done so far is examined a substantial heterochronous ontogenetic trend in a clade of chasmosaurine ceratopsians. I also think they put the desire to revise the taxonomy (the cart) before they determined the systematic implications of their ontogenetic scheme (the horse). This is simply backwards. I wonder how Scannella & Horner would consider the option of renaming Triceratops prorus something like “Eutriceratops” prorsus. I have just as much a reason to split the species into “genera” as to lump disparate species into a single genus for no sake than similar ontogeny. If biogeography or biostratigraphy is a viable option for distinguishing species, then may I use a formational boundary to define taxa? if there is none, but there is morphological variation, could i synonymize? The subjectivity abounds, and that is the problem with this approach.

[n1] While we’re on the way to confessions, I think Giraffatitan is a perfectly good container for Brachiosaurus brancai, but I’m not quite sure the reasoning is sound enough to accept it over, say, any other generic renaming of any species.

Farke, A. A. 2011. Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the Upper Cretaceous Lance Formation of Wyoming, U. S. A. PLoS ONE 6(1):e16196.
Forster, C. A. 1996. Species resolution in Triceratops: cladistic and morphometric approaches. Journal of Vertebrate Paleontology 16:259–270.
Hatcher, J. B., Marsh, O. C., Lull, R. S. 1907. The Ceratopsia. United States Geological Survey, Monographs 49:1–300.
Mateus, O. 2008. Two ornithischian dinosaurs renamed: Microceratops Bohlin, 1953 and Diceratops Lull, 1905. Journal of Paleontology 82(3):423.
Ott, C. J. & Larson, P. L. 2010. A new, small ceratopsian dinosaur from the Latest Cretaceous Hell Creek Formation, northwest South Dakota, United States: A preliminary description. p203-219 in Ryan, Chinnery-Allgeier & Eberth (eds.) New Perspectives on Horned Dinosaurs: the Royal Tyrrell Museum Ceratopsian Symposium. (Indiana University Press, Bloomington.)
Scannella, J. B. & Horner, J. H. 2010. Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): Synonymy through ontogeny. Journal of Vertebrate Paleontology 30(4):1157–1168.
Scannella, J. B. & Horner, J. H. 2011.Nedoceratops‘: An example of a transitional morphology. PLoS ONE 6(12):e28705.
Sullivan, R. M. & Lucas, S. G. 2010. A new chasmosaurine (Ceratopsidae, Dinosauria) from the Upper Cretaceous Ojo Alamo Formation (Naashoibito Member), San Juan Basin, New Mexico. p169-180 in Ryan, Chinnery-Allgeier & Eberth (eds.) New Perspectives on Horned Dinosaurs: the Royal Tyrrell Museum Ceratopsian Symposium. (Indiana University Press, Bloomington.)
Ukrainsky, A. S. 2007. A new replacement name for Diceratops Lull, 1905 (Reptilia: Ornithischia: Ceratopsidae). Zoosystematica Rossica 16(2):292.
Ukrainsky, A. S. 2009. Synonymy of the genera Nedoceratops Ukrainsky, 2007 and Diceratus Mateus, 2008 (Reptilia: Ornithischia: Ceratopidae). Paleontological Journal 43(1):116.
Wu, X-C., Brinkman, D. B., Eberth, D. A. & Braman, D. R. 2007. A new ceratopsid dinosaur (Ornithischia) from the uppermost Horseshoe Canyon Formation (upper Maastrichtian), Alberta, Canada. Canadian Journal of Earth Science — Revue canadienne de Sciences de la Terre 44(9):1243-1265.

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13 Responses to I Cannot Compel to Reason: Triceratops, We Done It Again

  1. Anonymous says:

    Strangely enough, back when the whole “Toroceratops” paper first came out, a friend of mine and I were discussing possible taxonomic schemes for these animals and came to a similar conclusion: that Torosaurus, Ojoceratops, Tatankaceratops, etc. could represent a species complex of Triceratops. It wouldn’t take much ontogenic tinkering to produce the variety of forms seen in the various “Triceratops” lineages. Scannella and Horner seem to consider the same hypothesis, but dismiss it rather quickly. I agree with you that they seem to want to put the cart before the horse.

  2. I think the problem with arguing that they should be focusing on species rather than “genera” is highlighted in the newest paper when the authors discuss how the variability of epioccipitals (or episquamosals or whatever they’re calling them now) changes with stratigraphy. The argument seems to be that “T. latus” sensu lato is synonymous with BOTH T. horridus and T. prosus. Determining which species latus should be sunk into means determining which holotype comes from a horizon closest to the holotype of latus. This kind of detailed stratigraphic work doesn’t seem to have been done yet, or at least not published yet.

    However I agree that the authors are frustratingly going about this backwards. Personally I would have finished the strat work and rigorously differentiated horridus from prorsus in the first paper, then determined which one is a synonym of latus, then assigned any remaining toro-morph specimens and N. hatcheri to their respective Triceratops species.

    In fact, given the apparently diagnosable variation over time present in the Lancian strata, it could well turn out that you could justifiably retain T. latus as a precursor species to T. horridus, prorsus, or whatever (depending on the strat level of the latus holotype). This could theoretically be used to revive other old species like gladius as “chronspecies”. At that point, whether to sink them all into Triceratops or split them all into separate “genera” or “chronspecies” or lump them as a single anagenetic species would be an artistic choice rather than a scientific one.

    • I think the problem with arguing that they should be focusing on species rather than “genera” is highlighted in the newest paper when the authors discuss how the variability of epioccipitals (or episquamosals or whatever they’re calling them now) changes with stratigraphy. The argument seems to be that “T. latus” sensu lato is synonymous with BOTH T. horridus and T. prosus. Determining which species latus should be sunk into means determining which holotype comes from a horizon closest to the holotype of latus. This kind of detailed stratigraphic work doesn’t seem to have been done yet, or at least not published yet.

      I’ve been told it is already pretty much worked out, and that the strat work has essentially preceded all of this, but that the systematic portion being presented now was preferred, especially in light of Horner’s work on the ontogeny in late Maastrichtian pachycephalosaurids. the authors argue that the variation in equiparietals is individual, and that the specimen noted in the paper lacks a mid-parietal epiparietal due to preservation, rather than as a taxonomically significant feature.

      At that point, whether to sink them all into Triceratops or split them all into separate “genera” or “chronspecies” or lump them as a single anagenetic species would be an artistic choice rather than a scientific one.

      But at that point it would be a lot easier to swallow.

    • DF says:

      The publications are coming as fast as they can be written and reflect the natural evolution of the research.

      Basically, we started out with a big mess of Trike morphology with little data to separate it out. The first step was Forster’s work on horridus and prorsus. The second step was identifying what changes occur ontogenetically (Horner & Goodwin paper). This provided a partial solution as it solved some morphologic issues (curvature of brow horns etc), but not others. We then started looking at the stratigraphy, including relocating sites for old specimens and collecting 60 or more new ones. Our new specimens have the best data of all. During this process the Trike-Toro paper was published. At the time the evidence was pretty good, but with more collecting and preparation, it is now much better.

      It would have been nice to have had all the data at the beginning, then the papers could have been published in the logical order that you state, but this isn’t how the data was accumulated, nor how the ideas evolved.

      These days we are conducting targeted collecting (and preparation) to try and fill in stratigraphic and ontogenetic gaps in our dataset. we have a really good picture of what is going on with the Triceratops clade, stretching from Ojoceratops time to the K-T boundary (roughly, 5 million years). There are a few outstanding issues that we can only resolve with more specimens, but right now we have a framework that can accommodate T. utahensis; Ojoceratops; Eotriceratops (etc). I understand that it is frustrating that this isn’t published yet: imagine how we feel on the writing end of things!

      Either way, I don’t anticipate any insurmountable problems with current (or future) rebuttals to the trike work. I acknowledge that we need to get some of this data out there, because it will help people see more clearly how the different morphologies fall into place. It’s actually a relatively straightforward situation, you just have to able to think about 4 (or more) axes of variation at the same time.

  3. Hikaru Amano says:

    (Note: I have posted this same message on Jan. 3, 2012 at the Hell Creek->Archosaur Website/Blog Discussion. Some minor modifications in the grammar-indicated by the presence of *- will be made for better clarity.)

    “Good Day everyone,

    One of the arguments of Dr. Scanella and Dr. Horner’s latest paper about Torosaurus as the senescence or old adult stage of Triceratops is based on the assumption eppocipitals are dividing into two by that stage. Although Dr. Farke stated that in well-sampled ceratopid taxa such as Centrosaurus, Styracosaurus, Chasmosaurus, and/or Pachyrhinosaurus, the number of epoccipitals remain constant or almost constant throughout ontogeny(adding only one or two on the each squamosal and on the coalesced pair of parietals), the former duo question whether the observed trend on the epoccipital numbers and/or positions also apply in chasmosaurines. They cited one double-peaked episquamosal as possible evidence in support of epoccipital division via resorption(and using that example to counter the argument that epoccipital numbers and positioning remain constant throughout ontogeny). However, much more specimens will be needed to confirm this interpretation and Dr. Farke, while he have not yet personally seen the said specimen, gave an alternative explanation-the tip of the epoccipital may just be eroding into a blunter shape without dividing into two. He also mentioned that the alternate explanation is rather common among ceratopids-many cases tend to erode the sharp regions of the epoccipitals (and other skull ornamentations)*only* to produce blunter shapes *and without splitting the eppocipitals*. This issue regarding the changes in epoccipital numbers and/or positions would be clarified by the discovery more juveniles subadult, young adult, and old adult specimens of *other* chasmosaurines(as Dr. Scanella and Dr. Horner themselves admitted in their paper that the number seen in Agujaceratops could also just as easily be due to individual variation). If the numbers and positions of epoccipitals in the juveniles, subadults, and young adults of other chasmosaurines are consistent with those of old adults, then the hypothesis that Triceratops was doubling their epoccipital numbers as they pass to old adult phase to become “Torosaurus” is in serious jeopardy.

    Since there are now quite plenty of papers about the skeletal morphologies of Triceratops and Tororsaurus(plus some considerable papers about their histology, ontogeny, and stratigraphy), what would be truly needed now is biomolecular examination(as I have argued many times in other blog sites). I do agree with the Paleo King that in many different groups of animals, sister species (and at times even sister genera) could differ in their respective consensus biomolecular profiles by as little as 1% or 2% (with regard to the differences in the sequences of DNAs *in* their identical genes or in the sequences of amino acids in those identical genes’ products)-not to consider the respective numbers of those equivalent genes’ copies and gene expression control mechanisms those sister taxa posses (a good example would be chimps and humans- their respective consensus biomolecular profiles differ by only 1% or so when it comes to *the DNA sequences both of them share*; the numbers of their equivalent genes’ copies are what amplify the difference to 3%). And there are also many cases in several various groups of vertebrates where the morphological differences between very closely related yet distinct species are not found in the skeleton *at all*, such as differences in the pattern and/or color distribution (remember Ashe’s spitting cobra-which was once considered as the black variant of the black-necked spitting cobra-difference in the integument color is the only constant morphological difference between the two). In performing biomolecular profiling for the Triceratops and Torosaurus, preserved soft tissues of good quality should be collected as extensively as possibly from as many samples as possible both to determine the consensus amino acid sequences(if sometime in the following years/decades some scientists managed to discover and extract some good-quality preserved DNA sequences *from Triceratops and Torosaurus remains*, that would be even better) and to eliminate-or at least minimize- the influence of diagenetic change in their biomoloecular profiles. To do that, I think much more research should be given to the associated post-cranial skeletons of both Triceratops and Torosaurus, especially bones in the limb regions(coincidentally, the post-cranial skeletons of ceratopids have morphologies that are highly conserved throughout phylogeny and ontogeny, hence soft tissues preserved in those bones are expected to have highly conservative biomolecular profiles). Examine the degree of similarity between the respective consensus amino acid sequences(or consensus DNA sequences-*if scientists manage to discover and extract them in the future*) of the two animals, combine the results of the biomolecular examination with the data from the morphological studies of the two animals). And since the samples came from the regions of the body whose morphologies are highly conservative in the phylogeny and ontogeny of ceratopids, the influence of gene expression control mechanisms associated with ontogeny are eliminated or at least minimized. As I have mentioned above, if even a 1% difference is observed between their respective consensus biomolecular profiles, combining that with the differences between their respective skeletal morphologies would contradict the ontogeny being implied by the histological analysis, and render the two as distinct yet closely related taxa.”

    References:

    Chimpanzee Sequencing and Analysis Consortium. (2005). Initial sequence of the chimpanzee genome and comparison with the human genome. Nature 437(7055).:69-87.

    Hikaru. (2011, November 22). Re: Nedoceratops – fun with science [Web log message]. Retrieved from The Open Source Paleontologist Blog, http://openpaleo.blogspot.com/2011/01/nedo…th-science.html.

    Hikaru. (2012, January 3). Re: Synonymy through ontogeny [Web log message]. Retrieved from Hell Creek->Archosaur Website/Blog Discussion, http://z13.invisionfree.com/Hell_Creek/index.php?showtopic=92&st=60.

    Itakura, E., Huang, R.R., Wen, D.R., Cochran, A.J. (2011). “Stealth” melanoma cells in histology-negative sentinel lymph nodes. Am J Surg Pathol., 35(11): 1657-65.

    Lindgren J, Uvdal P, Engdahl A, Lee AH, Alwmark C, et al. (2011) Microspectroscopic Evidence of Cretaceous Bone Proteins. PLoS ONE 6(4): e19445. doi:10.1371/journal.pone.0019445

    Ryan, M.J., Russel, A.P., Eberth, D.A., and Currie, P.J. (2001). The Taphonomy of a Centrosaurus (Ornithischia: Certopsidae) bone bed from the Dinosaur Park Formation (Upper Campanian), Alberta, Canada, with comments on cranial ontogeny. Palaios, 16(5): 482-506.

    San Antonio JD, Schweitzer MH, Jensen ST, Kalluri R, Buckley M, et al. (2011) Dinosaur Peptides Suggest Mechanisms of Protein Survival. PLoS ONE 6(6):
    e20381. doi:10.1371/journal.pone.0020381.

    Scannella, J., & Horner, J. (2011). ‘Nedoceratops’: An Example of a Transitional Morphology PLoS ONE, 6 (12) DOI: 10.1371/journal.pone.0028705

    Schweitzer, M.H., Wittmeyer, J.L., and Horner, J.(2007). Soft tissue and cellular preservation in vertebrate skeletal elements from the Cretaceous to the present. Proc. R. Soc. B. 274, 183-197.

    Switek B. (2011, December 15). Nedoceratops: to be, or not to be?. Retrieved January 3, 2012, from http://blogs.smithsonianmag.com/dinosaur/2…e-or-not-to-be/.

    Wildman, D.E., Uddin, M., Liu, G., Grossman, L.I., Goodman, M. (2003). Implications of natural selection in shaping 99.4% nonsynonymous DNA identity between humans and chimpanzees: Enlarging genus Homo. Proceedings of the National Academy of Sciences of the United States of America, 100(12): 7181-7188.

    Woolfe A, Goodson M, Goode DK, Snell P, McEwen GK, et al. (2005) Highly Conserved Non-Coding Sequences Are Associated with Vertebrate Development. PLoS Biol 3(1): e7. doi:10.1371/journal.pbio.0030007.

    Wuster, W. and Broadley, D.G. (2007). Get an eyeful of this: a new species of giant spitting cobra from eastern and north-eastern Africa (Squamata: Serpentes: Elapidae: Naja). Zootaxa 1532, 151-168.

    • I’m not sure the science is derived enough right now to permit DNA testing in any fashion. It is certainly not complete enough, as even more recent samples from Neanderthals require massive amounts of work to recover decent samples. That said, while the effect of the epiparietal ossification on the species identification issue is compelling against Torosaurus being Triceratops, it is one data point, and does not counter the remainder of Scannella and Horner’s argument. One point versus many is limited, and the S&H argument is, as it stands, pretty compelling. I believe, as Johns Scannella and Horner have stated themselves, that the best solution is increased sampling and the actual discovery of chasmosaurine juveniles in the terminal Maastricthian with clear “Torosaurus” morphology, rather than “Triceratops” morphology, and this includes the 6 or so epiparietal ossifications per side. It is by far the best test at the moment, using only morphology.

      • Hikaru Amano says:

        I concur with you that molecular paleontology is not yet advanced enough to permit DNA sequence examination for fossils dating back to the Mesozoic. However, based on a number of papers I have seen since 2005 , I believe it is now mature enough(in my opinion) to allow preliminary amino acid sequence analysis. Since amino acids are more conservative than DNA (in the sense that one amino acid could be specified by many codon), even a slight difference between the respective consensus amino acid sequences of the two animals could spell huge differences between their respective consensus DNA sequences(I have forgotten to emphasize in my earlier post here that for biomolecular profile examination of Triceratops and Torosaurus, soft tissue samples should be collected from fossils coming from different preservation conditions in order to eliminate-or at least minimize- the effect of diagenesis to the differences between their respective consensus biomolecular profiles). That said, it surely would still good for molecular paleontology to mature to the point where we good-quality preserved DNA sequences could be extracted(naturally that would also require the discovery of much more excellent quality fossils from different preservation conditions) for DNA sequence analysis in order to compare with the observations done using morphological, histological, and/or biostratigraphic analyses. But as of the moment, what we could do with the preserved amino acid sequences(if they could be extracted) from Triceratops and Torosaurs fossils is predictive reverse genetics(since the sequence of amino acids could hint at the possible sequences of RNAs that produce them, which in turn would allow one to figure out the possible DNA sequence of the gene that produced it). The only trick with here is the respective number of copies of the identical genes’ the two animals share.

        References:

        Asara JM, Schweitzer MH, Freimark LM, Phillips M, Cantley LC (2007) Protein sequences from Mastodon and Tyrannosaurus rex revealed by mass spectrometry. Science 316: 280–285.

        Manning,P.L., Morris,P.M., McMahon,A., Jones,E., et al. (2009). Mineralized soft-tissue structure and chemistry in a mummified hadrosaur from the Hell Creek Formation, North Dakota (USA). Proc. R. Soc. B, 276(1672): 3429-3437.

        Schweitzer MH, Wittmeyer JL, Horner JR. (2007a). Soft tissue and cellular preservation in vertebrate skeletal elements from the Cretaceous to the present.Proc R Soc Lond B 274: 183–197.

        Schweitzer MH, Suo Z, Avci R, Asara JM, Allen MA, et al. (2007) Analyses of soft tissue from Tyrannosaurus rex suggest the presence of protein. Science 316: 277–280.

        Schweitzer, M. H. et al. 2009. Biomolecular Characterization and protein sequences of the campanian hadrosaur B. canadensis. Science 324:626-631.

        San Antonio JD, Schweitzer MH, Jensen ST, Kalluri R, Buckley M, et al. (2011) Dinosaur Peptides Suggest Mechanisms of Protein Survival. PLoS ONE 6(6): e20381. doi:10.1371/journal.pone.0020381

        • Understand that the authors have yet to substantiate that the proteins are natural to the materials they are working on, and that DNA is, even partially preserved, only that amino acids that are similar to DNA molecules are present. DNA also requires certain degrees of completeness to ensure resolution which may not be . There has been argument from some opposition that the material is contaminated or represents bacterial “leavings” in the bone during burial. While I would rely on Schweitzer et al. to take their time in developing their proofs, this leaves the question currently in doubt. But even if they were available, these tissues seem to be viable only in a certain preservational scheme. It is also important to note that of the various taxa represented as potentially synonymous, they are confined to less than 5ma of time, and are nonetheless recognized as sister taxa by dissenting analyses. What does it prove when even human mt and nDNA cannot securely recover similar phylogenetic trees for Neanderthal-Denisovan-Modern relationships? If even the “Toroceratops” issue were to represent a reticulated arrangement of taxa, it may be best to treat these as a single operational taxon, for which Triceratops was chosen by Scannella and Horner. This seems far better and efficient, as argued, than the alternative.

          • Hikaru Amano says:

            “…and that DNA is, even partially preserved, only that amino acids that are similar to DNA molecules are present.”

            -I don’t actually understand what you’re mentioning here. If I may kindly ask, could you elaborate on this for better clarity?

            Also, Schweitzer et al. have shown in some of their later works that they have performed analyses confirming that those dinosaur amino acid sequences are genuine (http://www.nature.com/news/2011/110614/full/news.2011.369.html; see the aforementioned references’ contents; I could send you soft copies of such if you want to).

            “…But even if they were available, these tissues seem to be viable only in a certain preservational scheme.”

            -This is precisely why I said this earlier: “…require the discovery of much more excellent quality fossils from different preservation conditions.”. This is in order to see if soft tissues in fossils recovered from other preservation conditions could yield similar results.

            “…It is also important to note that of the various taxa represented as potentially synonymous, they are confined to less than 5ma of time, and are nonetheless recognized as sister taxa by dissenting analyses. What does it prove when even human mt and nDNA cannot securely recover similar phylogenetic trees for Neanderthal-Denisovan-Modern relationships?”

            -Just like what you said in Dinosaur Mailing List, I also don’t care about those taxa’s “labels” when scientists perform phylogenetic analysis. My argument here is whether or not they are synonymous or distinct at the biomolecular level, and how synonymous are they(generic or specific?). Yes, polytomy also occurs in DNA sequence analysis even in living taxa(which may be caused by factors such as homoplasies, reversions, frameshift mutations, substitutions, codon usage biases, etc.), more so if the DNA sequences being examined are insufficiently complete(as you yourself also noted) yet somehow DNA sequence analysis and/or amino acid sequence analysis may help other types of phylogeny analyses elucidate the possible relationships of closely-related yet non-synonymous taxa. This is where biostratigraphy comes-it may allow one to see how the population’s biomolecular profile deviates from the Hardy-Weinberg principle over the course of 5 million years(that is actually pretty long), starting with the stratigraphically oldest taxon(if they could recover good quality soft tissues in amounts that would allow biomolecular examinations) and up to 65-million year old Triceratops horridus/Triceratops prorsus fossils.

            Well, I’m not yet convinced of Drs. Scanella and Horner’s hypothesis of Torosaurus being the senescent or old adult stage of Triceratops, but at least I strongly agree with the Dr. Horner’s advocacy of molecular paleontology (as he stated once in a Discovery Channel program; I’ve just forgotten its title).

            (P.S.: May I kindly as you to tell me how to properly subscribe to the Dinosaur Mailing List? For months I have been trying to subscribe to authors there such as yourself, Dr. Fowler, Dr. Farke, Dr. Holtz, etc.,but failed. I also got this message when I tried to ask for help:
            >SUBSCRIBE HIKARU AMANO

            SUBSCRIBE: Unknown list name HIKARU

            If you wish to contact a person, please send mail to listmgr@usc.edu.
            To get general help on Listproc, please send the command:

            HELP

            in the body of the message to listproc@usc.edu.
            PS: Any subsequent requests you might have submitted in the same message
            have been ignored. Thanks for this discussions. I surely love engaging in dinosaur-related debates especially because there are a few paleontologists here in the Philippines.)

          • http://dml.cmnh.org/about.html: You must send the message “SUBSCRIBE DINOSAUR HIKARU AMANO” to listproc@usc.edu, not to any particular member. The statement should be in the body of the message, not the subject.

  4. Hikaru Amano says:

    thanks, Jaime.

  5. Pingback: “Toroceratops” Matters, as an Open Discussion | The Bite Stuff

  6. Randy2 says:

    The situation may be messier than that. Triceratops could have in fact been what a young Torosaur looked like, but as the species evolved, it may have come to look like Torosaur even when young. We’re not looking at a snapshot of a single decade with these fossils.

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