Field of Science

New Triassic Papers in the Festschift in Honor of Dr. Wann Langston Jr.

Back in very early 2010 Dr. Ernie Lundelius was honored with a festschift volume.  When I congratulated him on it he lamented that his close friend and colleague Dr. Wann Langston Jr., still did not have a festschift in his honor.  Ernie said they had tried to get one going a few times but nothing had ever come of it. I agreed to help to start another one and after several trials am proud to announce that the first online papers are now available from the Earth and Environmental Transactions of the Royal Society of Edinburgh. The final print volume will be out a bit later.  Unfortunately Dr. Langston passed away earlier this year and did not get to see the completed volume; however he did get to see a compilation of the abstracts.

Dr. Langston was Charles L. Camp's graduate student at the University of California at Berkeley and althogh his dissertation was on Permian vertebrates of North America, one of his firs publications was a description of a new phytosaur from the Upper Triassic of Texas.  Thus it is fitting that there are a few Triassic papers in his festschrift volume.  Two, which I was involved with, are up currently: I'll post the rest when they come online.

Parker, W. G. 2013. Redescription and taxonomic status of specimens of Episcoposaurus and Typothorax, the earliest known aetosaurs (Archosauria: Suchia) from the Upper Triassic of western North America, and the problem of proxy “holotypes”. Earth and Environmental Transactions of the Royal Society of Edinburgh First View Article. DOI: http://dx.doi.org/10.1017/S1755691013000212

Abstract - Historic type and referred material of the aetosaurian taxa Typothorax coccinarum, Episcoposaurus horridus and Episcoposaurus haplocerus are redescribed and the non-aetosaurian material identified and removed, a task previously considered “hopeless”. Reexamination of the original material reveals that the holotypes of E. haplocerus and probably T. coccinarum are not diagnosable at the species level and therefore are nomena dubia. The next available names for material referred to these taxa are Desmatosuchus spurensis and E. horridus respectively, although it may be more desirable for reasons of taxonomic stability to attempt to petition for a neotype in the latter case. The redescription of historical specimens is necessary to determine their nomenclatural validity. The use of referred specimens as proxy “type” specimens is problematic, as these referrals were originally made not on the basis of apomorphies, but rather on biostratigraphic and/or geographical assumptions which are inherently circular and cannot be unambiguously supported.

Martz, J. W., Mueller, B., Nesbitt, S. J., Stocker, M. R., Parker, W. G., Atanassov, M., Fraser, N., Weinbaum, J., and J. R. Lehane. 2013. A taxonomic and biostratigraphic re-evaluation of the Post Quarry vertebrate assemblage from the Cooper Canyon Formation (Dockum Group, Upper Triassic) of southern Garza County, western Texas. Earth and Environmental Transactions of the Royal Society of Edinburgh First View Article. DOI: http://dx.doi.org/10.1017/S1755691013000376

Abstract - The Post Quarry, within the lower part of the type section of the Upper Triassic Cooper Canyon Formation in southern Garza County, western Texas, contains a remarkably diverse vertebrate assemblage. The Post Quarry has produced: the small temnospondyl Rileymillerus cosgriffi; the metoposaurid Apachesaurus gregorii; possible dicynodonts and eucynodonts; a clevosaurid sphenodontian; non-archosauriform archosauromorphs (Trilophosaurus dornorum, simiosaurians, and possibly Malerisaurus); the phytosaur Leptosuchus; several aetosaurs (Calyptosuchus wellesi, Typothorax coccinarum, Paratypothorax, and Desmatosuchus smalli); the poposauroid Shuvosaurus inexpectatus (“Chatterjeea elegans”); the rauisuchid Postosuchus kirkpatricki; an early crocodylomorph; several dinosauromorphs (the lagerpetid Dromomeron gregorii, the silesaurid Technosaurus smalli, a herrerasaurid, and an early neotheropod); and several enigmatic small diapsids. Revised lithostratigraphic correlations of the lower Cooper Canyon Formation with the Tecovas Formation, the occurrence of Leptosuchus, and the overall composition of the assemblage indicate that the Post Quarry falls within the Adamanian biozone, and not the Revueltian biozone. Stratigraphic subdivision of the Adamanian biozone may be possible, and the Post Quarry may be correlative with the upper part of the Adamanian biozone in Arizona. The age of the Post Quarry assemblage is possibly late Lacian or earliest Alaunian (late early Norian or earliest middle Norian), between 220 and 215 Ma.







8 comments:

  1. Not even one phytosaur papar?
    I've been expecting to see at least the three I heard of..

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  2. Not all of the papers are out yet. Three of them do deal with phytosaurs.

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    1. I've been aware of the three phytosaur papers for over several months now. Two of them deal with Machaeroprosopus (one demonstrating that Machaeroprosopus is congeneric with Pseudopalatus, and the other describing a new species of Machaeroprosopus from Texas), while the third will coin a new name for "Paleorhinus" scurriensis. I look forward to reading the first two phytosaur papers!

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  3. After reading the abstract of the paper about the original specimens of Typothorax and Episcoposaurus, I didn't think that Episcoposaurus haplocerus would be mentioned in the paper because it was already declared a nomen dubium in the 2008 paper describing a new specimen of Desmatosuchus from Arizona, even though haplocerus is clearly Desmatosuchus (Parker 2008). However, using Episcoposaurus as the next available for specimens referred to Typothorax would be detrimental to nomenclatural stability and so a neotype from the type locality of Typothorax (not the lectotype of Episcoposaurus) may be desirable (unless some of the syntypes of E. horridus do belong to the same individual as the original specimen of Typothorax as suggested by Lucas et. al. 2007).

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  4. According to the ICZN Episcoposaurus horridus is the next available name for T. coccinarum. The removal of E. haplocerus from the genus does not affect this as it is not the type species. I agree that it would be best however to try to keep the name Typothorax. The original syntypes are so scrappy that it would be difficult to say if any of the other material is from the same specimen. However, I think that a portion of the E. horridus syntype series may in fact be part of the material that Cope referred to the genus in 1887. There is some confusion with the Lucas et al (2007) article because they erroneously consider this referred material to be part of the syntype series of T. coccinarum. In any case it would be best to designate the 1887 referred material as the neotype even though everyone has been using the Canjilon Quarry Typothorax as the reference for years.

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  5. Now for the statement in the abstract by Martz et. al. (2013):

    "Revised lithostratigraphic correlations of the lower Cooper Canyon Formation with the Tecovas Formation, the occurrence of Leptosuchus, and the overall composition of the assemblage indicate that the Post Quarry falls within the Adamanian biozone, and not the Revueltian biozone. Stratigraphic subdivision of the Adamanian biozone may be possible, and the Post Quarry may be correlative with the upper part of the Adamanian biozone in Arizona. The age of the Post Quarry assemblage is possibly late Lacian or earliest Alaunian (late early Norian or earliest middle Norian), between 220 and 215 Ma."

    It looks like the use of Typothorax coccinarum as an index fossil of the Revueltian may be dubious, and Machaeroprosopus may be the only vertebrate genus of use as an index taxon of the Revueltian.

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  6. "it would be best to designate the 1887 referred material as the neotype" - in this case Episcoposaurus and its type species will be synonyms of the type Typothorax species, right? Is there going to be a formal patition for the neotype?

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  7. "It looks like the use of Typothorax coccinarum as an index fossil of the Revueltian may be dubious, and Machaeroprosopus may be the only vertebrate genus of use as an index taxon of the Revueltian."

    Yes, Parker and Martz (2011) stated this explicitly.

    As far as formally petitioning the ICZN I have no plans to do so personally. I'm leaving that to colleagues who work on Typothorax. There is much more undescribed material available that will come to light over the next few years. Someone also needs to reevaluate the type specimen and status of Typothorax antiquum.

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