There are 2 bonebeds for Triceratops/Torosaurus that have been published on – the Burpee’s Homer site (not monospecific) and the Torosaurus cf. utahensis site in the Javelina Formation in Big Bend National Park (Monospecific)

Reference:

Hunt, R., & Lehman, T. (2008). Attributes of the Ceratopsian Dinosaur Torosaurus, and New Material from the Javelina Formation (Maastrichtian) of Texas Journal of Paleontology, 82 (6), 1127-1138 DOI: 10.1666/06-107.1

Mathews, J. C., Brusatte, S. L., Williams, S. A. and Henderson, M. D. 2009. The first Triceratops bonebed and its implications for gregarious behavior. Journal of Vertebrate Paleontology 29(1):286-290.

I don’t question it as a method to establish the degree of maturity of individuals being studies. My argument revolves around the issue of using histology as a means to synonymize/split taxa. As I’ve argued many times here and in other blog sites, without knowledge to the molecular profiles and/or external morphologies of the closely-related taxa being studied, finding individuals from those taxa (with individuals of one taxon/taxa having a different degree of maturity to the individuals of the other taxon/taxa) histogolical analysis could result in a superficial lumping of the taxa being studied.

Concerning the Triceratops horridus bonebed Homer site, here is the citation for that paper(which I forgot to include in the earlier comment). And oh, I forgot to edit the felid example I have written in the last parenthesis of my earlier comment’s first paragraph(that should have been clouded leopard instead of snow leopard).

Reference:

Mathews, J. C., Brusatte, S. L., Williams, S. A. and Henderson, M. D. 2009. The first Triceratops bonebed and its implications for gregarious behavior. Journal of Vertebrate Paleontology 29(1):286-290.

No offense intended for anyone in here. When I used grey whales and right whales here for examples, I am referring to a hypothetical situation wherein these animals have lived and became extinct a long time in the past and we only have their bones for analysis. Without knowledge of their external morphology (or molecular profile for that manner), one could actually make the mistake of regarding the size differences in cranial material and mandibles as different phases of ontogeny. To cite another group, suppose tigers and clouded leopards (the genera Panthera and Neofelis, respectively, are sister taxa) have been extinct for the past 65 million years, (with only their skeletons available for study) and happened to have lived in the same area. Taking the same scenario as what I’ve mentioned in the earlier comment (this time a subadult snow leopard died in the same area as an old adult tiger), the person who will conduct histological axamination of those animals’ remains may falsely result in the clouded leopard skeleton as the subadult form of the tiger skeleton found in the same formation.

I don’t actually disagree with the concept of Torosaurus as the senescence phase of Triceratops. But personally, I still think that even with a large sample size for Triceratops and Torosaurus, we still need the evidence for monospecific bonebeds (not just the Homer bonebed of adolescent Triceratops, we should also examine the bonebeds that Bruce Erickson and Barnum Brown claimed to have found and then try to find some more). If Torosaurus are also found to be associated rather consistently with those bonebeds, then perhaps Scanella and Horner may be right. Also, I have read a news article where Dr. Nick Longrich will perform histological analysis on the Torosaurus skulls in Yale collections since according to him such specimens have features of adolescent or subadult individuals (such as unfused skull bones). I just wonder if he has finished his research and it will surely be noteworthy to know about that. About molecular paleontology, I think what should be done with Triceratops and Torosaurus is put a slightly less emphasis on fossil skulls and more emphasis in post-cranial bones that could harbor preserved soft tissues(just like what Asara, Horner, and Schweitzer did with the T. rex and Brachylophosaurus fossils, or the research done by Dr. Manning and his team on the preserved soft tissues of the Edmontosaurus mummy in 2007). Schweitzer had published in 2007 about the preservation of blood vessels in 65-million year old Triceratops horridus rib.

As what is being demanded by other scientists, more post-cranial fossils (ribs, hip bones, femora, humeri, etc.) from different preservation conditions (such as Triceratops and Torosaurus remains from sandstone deposits vs. Triceratops and Torosaurus remains from mudstone deposits) should be collected examined for the presence of soft tissues in good condition. Then perform a qualitative molecular analyses to determine if diagenesis occurred in the molecular profile of soft tissues recovered from Torosaurus and Triceratops. If the consensus molecular profiles of Triceratops and Torosaurs remain consistent even if different samples are obtained from different preservation conditions, then diagenetc alteration may be eliminated rather safely from potential sources of chemistry differences.

I strongly agree with with Dr. Horner, Dr. Schweitzer, Dr. Asara, and Dr. Manning in their advocacy of using molecular examination methods to discover the phylogeny of dinosaurs as accurately as possible in ways that skeletal morphology and/or histology alone cannot satisfactorily solve. And as I have said before, many distinct yet closely related species may have identical skeletal morphologies yet vary only in their molecular profiles and/or have morphological characters that are not based on the skeleton at all (for example, Ashe’s spitting cobra was regarded as a subspecies of Black-necked spitting cobra due to slight color differences-it is only in 2007 when molecular profiling rendered the two as separate yet closely-related species).

Literature cited:

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

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.

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.

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.

Yu, L. and Zhang, Y. (2005). Phylogenetic studies of pantherine cats (Felidae) based on multiple
genes, with novel application of nuclear β-fibrinogen intron 7 to carnivores. Mol Phylogenet Evol. 35(2): 483-495.

Several points, some more minor than others:

1) There aren’t any “skin samples” from Triceratops. There are specimens with skin impressions, but it is effectively a trace fossil – an impression in the sediment from the skin. There’s no soft tissue preservation. Fossilized ‘soft tissue’ samples would be needed from the interior of bones – and thus far the samples to my knowledge have not been obtained.

2) That being said, the field of molecular paleontology is so new and there are still so many skeptics that I doubt your suggestion would really persuade many people. Otherwise, any perceived differences in chemistry could just as easily be due to diagenetic alteration.

3) You should probably read more on histology. If you find it so unreliable, perhaps you should publish something.

4) If there were crania or jaws, any cetologist who made a mistake of confusing eschrichtiid and balaenid skeletons even of different sizes would be laughed at.

5) So far, no monospecific bonebeds have been discovered for Triceratops or “Torosaurus”. That being said, these are the only ceratopsians that occur at all in Maastrichtian strata like the Hell Creek Formation (discounting “Tatankaceratops”). Lastly, although I frequently hear people chanting “more fossils…”, the sample size for Triceratops (& Toro) is now one of the largest for ceratopsids, and one can easily view the birth of the Triceratops/Torosaurus hypothesis as being the result of the improved sample size.

As what I have written in other blog sites before, both the supporters and critics of this hypothesis have strong arguments and counter-arguments. The single example of a double-peaked squamosal eppocipital may have been caused not by resorption but by a traumatic event(such as being hit by another Triceratops horn). But even if division (via resorption) happened in squamosal epoccipitals, it does not necessarily mean the same thing happened in parietal epoccipitals. More specimens of both chasmosaurines and centrosaurines from all ages (starting from youngsters that possess nodes corresponding to eppocipital positions to old adults where fusion of eppocipitals to the crest margins is complete) needed to be examined to discover if epoccipital numbers doubled and positions varied throughout ontogeny. Also, the depressions on the coalesced pair of parietals which Farke claimed were regions of neck muscle, and claimed by Scanella and Horner to be areas of fenestration, needs further investigations since even the latter themselves claimed that those regions may have been covered by periosteum, hence indirect muscle insertion may have happened after all (Muhl and Gedak, 1986). My view is that what will finally settle this issue are biomolecular examination. (as stated in my blog at Dr. Farke’s blogspot, but with few corrections as enclosed in a pair of dashes) “…subject the skin samples from the Triceratops (?T. horridus) “mummy” found by Dr. Bakker plus preserved soft tissues in Triceratops bones (if present and in good quality) to a qualitative molecular examination to see if there are any usable traces of peptides from that ‘mummy’; if there are, collect as many samples”-as possible-”to determine the consensus amino acid sequence of Triceratops as comprehensively as possible. Do the same for the ‘Torosauri’ specimens; then subject them to amino acid sequence analysis (one can even perform probabilistic reverse genetics since the present sequence of amino acids hints at the possible sequence of DNAs that produced it). As I have said before, in even a 1% or 2% difference-in amino acid sequences-(with regards to equivalent genes; other factors such as the differences in respective numbers of those identical genes’ copies and gene expression control mechanisms present in those taxa are anybody’s guess with our current technology) in the molecular composition of two taxa can render them as separate but very closely related (i.e. humans and chimps). If the molecular data contradicts the morphological ontogeny implied by histological data, then there is a significant possibility that Torosaurus is indeed valid. “. Compare the results from molecular examination with morphological analysis and if the results of the two have high degree of similarity, that would refute the ontogeny being implied by the histological tests. Wiht regard to histological analysis, I find it quite unreliable (and potentially in establishing synonymy via ontogeny considering that in many different groups of animals, very closely related yet separate species and/or genera can have identical skeletal mophologies and are distinct only at the genetic level or have morphological variations that are not based on the skeleton at all (such as pattern and/or color distribution in the integument, relative sizes to one another, etc.). I have written before that it’s possible for sister species or genera to have highly identical skeletal morphologies, and that if individuals of two very closely related yet distinct genera (let’s say, grey whales and right whales) happened to have died and fossilized at the same site (with the individuals of the former being subadults and the individuals of the latter species being young adults and old adults), then it’s highly possible that subjecting the bones of those individuals to histological analysis will falsely result in the individuals of grey whales being regarded as subadults of right whales. Another approach, although less reliable than molecular analysis, is the discovery of monospecific bonebeds where there are Triceratops of all ages(nestlings, puppies, juveniles, subadults, young adults, and old adults). If there are Torosauri there, then perhaps the latter scientists are right (that Torosaurus is the old adult phase of Triceratops).

Literature cited:

Muhl, C.F., and Zedak, G.K. (1986). The influence of periosteum on tendon and ligament migrations. J. Anat. (1986), 145:161-171.

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/nedoceratops-fun-with-science.html.

The oddest element to this is that both Farke and Scannella and Horner may be correct, in many ways: the ontogeny can be peculiar and unique to ceratopsids, with investigation into how weird it is to other ceratopsids, especially in the paedomorphic retention of a solid frill until into late adulthood, or the peramorphic facial elongation and metaplastic trasformation of the frill ultrastructure and horns. Farke’s proposition may result in multiple taxa among a complex of what can be “chronospecies,” segments of an anagenetic lineage of forms, all essentially one long continuous transition through time, but broken up into useful elements. The work is continuing, and is certainly not settled.

And statistically, the odds of fossilization and discovery for a morphologically odd or pathological individual have to be relatively small.