Petrified Forest Fieldwork Photos - 2008

All of this nasty ice and freezing weather has me longing for summer and fieldwork again. Here are some photos from work in the park this past summer to warm us up a little. The above photo is a picture of a phytosaur skull excavation from May of this year.

Here is our fossil preparator Matt Brown precariously perched excavating a small metoposaurid skull.

Summer intern Kate Hazlehurst working on some poposaurid material from the Sonsela Member.

Poposaurid pubis in-situ.

Myself and Matt Brown carving (literally) a phytosaur skull out of its sandstone tomb. This complete skull is from the type locality of Pseudopalatus jablonskiae and may belong to the same taxon.

Me again, with intern Joanna Panosky excavating aetosaur (Typothorax) plates.


One of the Typothorax plates.

Just to rub it in a little, all of these sites are within an hour drive/hike of my office. Such is the beauty of the Petrified Forest National Park. Hope these warmed you up a bit (at least those of us in the Northern Hemisphere).

The vertebrate assemblage of the Late Triassic Canjilon Quarry and the importance of apomorphy based assemblage comparisons

Nesbitt, S.J., and M.R. Stocker. 2008. The vertebrate assemblage of the Late Triassic Canjilon Quarry (Northern New Mexico, USA) and the importance of apomorphy based assemblage comparisons. Journal of Vertebrate Paleontology 28:1063-1072.

ABSTRACT—The Upper Triassic Canjilon Quarry in northern New Mexico preserves a vertebrate assemblage typical of the Norian Stage of North America. Although dominated in relative abundance by the phytosaur Pseudopalatus and the aetosaur Typothorax, a more diverse assemblage of smaller forms was previously reported. Additions to the Canjilon
Quarry vertebrate assemblage are critically reviewed and described using an apomorphy-based method for assigning taxa. An apomorphy-based approach for compiling and comparing assemblages allows each taxonomic assignment to be a testable hypothesis. Fragmentary yet diagnostic elements that may not be assignable to a species-level taxon can be assigned to a larger clade and thus provide useful information. Additionally, each taxon listed in the assemblage must be tied to a diagnostic specimen listed with a museum specimen number. Using this method for the Canjilon Quarry, we establish the presence of an assemblage that is more similar to other vertebrate quarries near Ghost Ranch than previously thought. The Canjilon Quarry assemblage is restricted to vertebrates from UCMP locality V2816. Vertebrate material housed at the Museum of Comparative Zoology, Harvard, which was reported from the Canjilon Quarry, was not collected from UCMP V2816 but from a nearby locality.

The Canjilon Quarry from the Petrified Forest Member (Chinle Formation) of New Mexico was mainly worked by Charles Camp and crew (University of California, Berkeley) in 1933 and produced a wealth of fossil vertebrate material, most notably numerous skeletons (including a suite of skulls) of the phytosaur Pseudopalatus. You can get more information on the Canjilon Quarry, including an extremely detailed reconstruction of the 1933 excavation from field notes, here and here. Of course the main point and overall importance of this paper is the discussion on using apomorphy based identifications when creating faunal lists.

New Triassic Critter Reconstructions

Not only is Jeff Martz a really good geologist and paleontologist he also is very skilled as an illustrator (check out his M.S. thesis Martz [2002], his skeletal reconstruction of Desmatosuchus [from Parker, 2008], and this link at Discovery News for other examples of his work). Jeff has recently initiated a new series of Late Triassic animal reconstructions from Petrified Forest National Park and has generously offered to let me share some of them on my site rather than showing them on his site. The park has been sorely lacking up-to-date reconstructions of many of its Triassic animals, as most existing reconstructions date from the 1980s and do not include the majority of new finds. This is the first of the series and I won't tell you what taxon this is. Instead I'll leave to you to guess its identity.
These represent slightly different reconstructions of the same animal. It is challenging to try to provide realistic yet thought provoking reconstructions, especially regarding skin color, texture, and soft tissue. The coloration and patterning of most animals fall into a few broad catagories including camouflage, disruptive patterning, and/or sexual display. The animal featured here is most likely a carnivore and thus was provided with more of a disruptive pattern that would allow the animal a mechanism to distract prey by making the body outline hard to see, and thus distance and speed difficult to judge. The upper reconstruction adds hypothesized soft parts including a 'dewlap' and other features which may or may not have been present, and thus are speculative yet feasible for display.

As long as Jeff is willing, I hope to provide more of these new reconstructions in the future.

REFERENCES

Martz, J.W. 2002. The morphology and ontogeny of Typothorax coccinarum (Archosauria, Stagonolepididae) from the upper triassic of the American Southwest. Unpublished M.S. thesis. Texas Tech University, Lubbock.

Parker, W.G. 2008. Description of new material of the aetosaur Desmatosuchus spurensis (Archosauria: Suchia) from the Chinle Formation of Arizona and a revision of the genus Desmatosuchus. PaleoBios , 28:1-40.

Chinle Silesaurid and the Importance of Field Notes

Adam Yates nailed it. The specimen is the proximal end of the right femur of a silesaurid (PEFO 34347) from the Upper Triassic Blue Mesa Member (Chinle Formation) of Arizona. This specimen is significant because it represents the only known unambiguous silesaurid element from the lower portion of the Chinle Formation and from Arizona. It demonstrates that silesaurids were a portion of the fauna at Petrified Forest National Park.

This specimen was discussed in more detail by Parker et al. (2006) and Nesbitt et al. (2007). It is identical to the proximal ends of the femora of Silesaurus opolensis (Carnian of Poland) and Eucoelophysis baldwini (Norian of New Mexico) and thus cannot be assigned to a specific genus although the age (Norian) and stratigraphic position (Chinle Formation) of the specimen would suggests that it is probably could represent Eucoelophysis rather than Silesaurus. However, until more material is found this cannot be considered. A key characteristic of the proximal end of the femur in Silesaurus, Eucoelophysis, and PEFO 34347 is that the element is triangular in proximal view and has a mediolaterally trending sulcus. Whereas this sulcus is present in other taxa, most notably the pseudosuchian Shuvosaurus, the femur of silesaurids differs in having a subrectangular femoral head in lateral view with a slightly offset head as in dinosaurs.

Now for the promised “interesting” (and frustrating) story regarding this specimen. This specimen was collected sometime in the late 1990s by an unknown individual who was part of a larger research project. It went unrecognized and was included in a large amount of material deemed unworthy of study and potentially to be disposed of. When going through this material to see if anything was salvageable I came across this specimen. Unfortunately, the exact spot where the specimen was collected was not recorded. There are no known field notes for the project and field tags contain minimal information, in this case just a vague geographical reference. This reference is enough to pinpoint the specimen to a small geographical area and limited stratigraphic level; however, it will be nearly impossible to find the rest of the specimen if it exists (and the break is clean, suggesting that more of the specimen was preserved and awaits discovery).

I cannot emphasize enough (and I stress this to, and require it from, all of my employees and interns) the importance of collecting and recording accurate field data on every specimen collected whether the specimen seems important or not. I don’t know how I would function without my past field notes when it comes to identifying and interpreting specific specimens. I have found when I get lax (because of time, weather, arrogance, etc..) I usually end of regretting not having a key piece of information regarding a specimen at some point. At the absolute minimum for EVERY specimen collected there should be GPS coordinates, a photograph of the site showing the surrounding landscape (most important), and a brief description of the sediments and stratigraphic position. Taphonomic notes are also extremely important and often forgotten. Bottom line, you cannot collect too much information. Anyone who has worked with older specimens when simply a stratigraphic unit and state were deemed sufficient information will understand. PEFO 34347 currently represents to earliest known silesaurid from North America, yet its provenance cannot be precisely determined and clarification regarding this specimen depends exclusively on luck. Was more of the specimen preserved? Is it still present and will we be able to stumble across it? I certainly hope so.

REFERENCES

Nesbitt, S.J., Irmis, R.B., and W.G. Parker. 2007. A critical re-evaluation of the Late Triassic dinosaur taxa of North America. Journal of Systematic Palaeontology 5:209-243.

Parker, W.G., Irmis, R.B., and S.J. Nesbitt. 2006. Review of the Late Triassic dinosaur record from Petrified Forest National Park, Arizona. Museum of Northern Arizona Bulletin 62:160-161.

Late Triassic Mystery Fossil #4

This is an interesting specimen with an interesting history.....and proof that, to be cliche, one person's junk is another person's treasure (especially if they don't know what they are looking at). Unfortunately that is only half the story, the rest is highly frustrating. Views are lateral and proximal. Scale bar is 1 cm.

First record of stereospondyls from the Upper Triassic of Brazil

Dias-da-Silva, S., Dias, E.V., and C.L. Schultz. 2009. First record of stereospondyls (Tetrapoda, Temnospondyli) in the Upper Triassic of Southern Brazil. Gondwana Research 15:131-136. doi:10.1016/j.gr.2008.07.002

Abstract - Stereospondyls survived the Permo-Triassic extinctions in a refuge probably located in the landmass that nowadays comprises Australia. Subsequently, they radiated to other parts of Pangaea, reaching their highest distribution and diversification during the Early Triassic. An incomplete interclavicle from the Caturrita Formation represents their first record in the Upper Triassic of Brazil. Previously, Upper Triassic South American stereospondyls were restricted to Argentina. This new record reinforces a former hypothesis that suggests the presence of a more diverse stereospondyl fauna in South America during the Late Triassic than previously assumed. Additionally, the presence of a stereospondyl and a phytosaur in the Caturrita Formation reinforces the hypothesis of a change to more humid climatic conditions in the Paraná Basin during the Upper Triassic. The record of Early Triassic stereospondyls in South America suggests that they first colonized Brazil and/or Uruguay, spreading from South Africa during the Early Triassic, subsequently reaching Argentina. Up till now, there is no record of Middle Triassic stereospondyls in either Argentina and Brazil, probably due to either taphonomic bias or insufficient prospecting. Despite the lack of direct evidence, one should not dismiss an earlier stereospondyl colonization of Argentina still during the Early or Middle Triassic.

Feather-like development of Triassic diapsid skin appendages

Thanks to Rob Taylor of the Theropod Archives who just posted on the Dinosaur Mailing List that Naturwissenschaften is freely available online through the end of the month. One of several Online First Titles that is of interest is this one...

Voight, S., Buchwitz, M., Fischer, J., Krause, D., and R. Georgi. Online First 2008. Feather-like development of Triassic diapsid skin appendages. Naturwissenschaften
DOI 10.1007/s00114-008-0453-1

Abstract - Of the recent sauropsid skin appendage types, only feathers develop from a cylindrical epidermal invagination, the follicle, and show hierarchical branching. Fossilized integuments of Mesozoic diapsids have been interpreted as follicular and potential feather homologues, an idea particularly controversially discussed for the elongate dorsal skin projections of the small diapsid Longisquama insignis from the Triassic of Kyrgyzstan. Based on new finds and their comparison with the type material, we show that Longisquama’s appendages consist of a single-branched internal frame enclosed by a flexible outer membrane. Not supporting a categorization either as feathers or as scales, our analysis demonstrates that the Longisquama appendages formed in a two-stage, feather-like developmental process, representing an unusual early example for the evolutionary plasticity of sauropsid integument.

The PDF and online supplemental material is also available from the same site.

Looking at Aetosaurs in a Whole New Way

Jeff Martz's recent post at Paleo Errata reminded me of this recent article which came out two months ago. Check it out, you can tell that the writer had a lot of fun with this, and the photo (see courtesy photo from http://www.santafenewmexican.com/ below) is great.

Of course, one comment made in the article regarding the similarity to modern crocodiles led to a Google search which turned up what could best be described as um....., you got it, croc porn.

All of this aside, what a great specimen of Typothorax!

On the Procompsognathus postcranium

F KNOLL (2008). On the Procompsognathus postcranium (Late Triassic, Germany)☆ Geobios, 41 (6), 779-786 DOI: 10.1016/j.geobios.2008.02.002

ABSTRACT - A review of the historical background of the material housed in the Staatliches Museum für Naturkunde (Stuttgart) and ascribed to Procompsognathus triassicus (Upper Triassic, Germany) is provided. The systematic position of the postcranial remains is discussed. The combined results of cladistic analyses suggest that the type material, an incomplete postcranial skeleton in two pieces (SMNS 12591), is from a theropod close to Segisaurus and Coelophysis. An isolated manus (SMNS 12352a) is definitely not theropodan, but could be from any small basal archosaur. The remarkable diversity of the carnivorous guild that dwelled in southern Germany before the end-Triassic events is underlined.

This is the latest paper in the Procompsognathus saga, regarding the taxonomic status of four specimens refered to this taxon, a purported theropod dinosaur, from the Late Triassic of Germany. To recap, Fraas (1913) named Procompsognathus triassicus based on a partial skeleton (SMNS 12591a) and skull (SMNS 12591), and refered it to the Dinosauria. Huene (1921) discussed the material further and assigned another partial skull (SMNS 12352) and manus (SMNS 12352a) from the same quarry to the taxon. Since that time this material has been reviewed by Ostrom (1981), Sereno and Wild (1992), Chatterjee (1993, 1998), Rauhut and Hungerbuhler (2000), Rauhut (2003), Allen (2004), and most recently by Knoll and Schoch (2006) which was an abstract previewing the current study by Knoll. All of these authors came to differing conclusions regarding the taxonomic affinities of the material as listed below:

Ostrom (1981)
SMNS 12591 - Procompsognathus triassicus
SMNS 12591a - Procompsognathus triassicus
SMNS 12352 - non Procompsognathus triassicus
SMNS 12352a - non Procompsognathus triassicus

Sereno and Wild (1992)
SMNS 12591 - Theropod similar to Coelophysis and Segisaurus
SMNS 12591a - Saltoposuchus connectens (Crocodylomorpha)
SMNS 12352 - Saltoposuchus connectens
SMNS 12352a - Saltoposuchus connectens

Chatterjee (1993, 1998)
SMNS 12591a - Theropod (contra Sereno and Wild [1992])

Rauhut and Hungerbuhler (2000)
SMNS 12591 - Theropod similar to Coelophysis and Segisaurus

Rauhut (2003)
Procompsognathus is a theropod but a metataxon

Allen (2004)
Procompsognathus is a non-dinosaurian ornithodiran

Knoll and Schoch (2006)
SMNS 12591 - Theropod similar to Coelophysis and Segisaurus
SMNS 12591a - Theropod, possibly tetanuran
SMNS 12352 - indeterminate crocodylomorph
SMNS 12352a - indeterminate crocodylomorph

The current paper (Knoll, 2008) follows the finding of Knoll and Schoch (2006) except that the isolated manus (SMNS 12352a) is considered to represent an unknown basal archosaur. Thus Knoll (2008) argues for a previously unrecognized diversity of carnivorous archosaurs in the Upper Triassic Stubensandstein. Hopefully this is the final word, but given the numerous differing hypotheses put forth this taxonomic argument may never be fully resolved.

The image is from here.

REFERENCES

Allen, D. 2004. The phylogenetic status of Procompsognathus revisited. Journal of Vertebrate Paleontology 24:34A.

Chatterjee, S. 1993. Procompsognathus from the Triassic of Germany is not a crocodylomorph. Journal of Vertebrate Paleontology 13:29A.

Chatterjee, S. 1998. Reassessment of the Procompsognathus skull, p. 6 in Wolberg, D.L., Gittis, K., Miller, S., Carey, L., and A. Raynor (eds.), Dinofest International. The Academy of Natural Sciences, Philadelphia.

Fraas, E. 1913. Die neuesten Dinosaurierfunde in der schwabischen Trias. Die Naturwissenschaften 1:1097-1100.

Huene, F.v. 1921. Neue Pseudosuchier und Coelurosaurier aus dem wurttembergischen Keuper. Acta Zoologica 2:329-403.

Knoll, F., and R. Schoch. 2006. Does Procompsognathus have a head? Systematics of an egnimatic Triassic taxon. Journal of Vertebrate Paleontology 26:86A.

Knoll, F. 2008. On the Procompsognathus postcranium (Late Triassic, Germany). Geobios 41:779-786.

Ostrom, J.H. 1981. Procompsognathus - theropod or thecodont? Palaeontographica A 175:175-195.

Rauhut, O.W.M. 2003. The interrelationships and evolution of basal theropod dinosaurs. Special Papers in Palaeontology 69:1-213.

Rauhut, O.W.M., and A. Hungerbeuhler. 2000. A review of European Triassic theropods. GAIA 15:75-88.

Sereno, P.C., and R. Wild. 1992. Procompsognathus: theropod, "thecodont", or both? Journal of Vertebrate Paleontology 12:435-458.

Proofing The Proof Corrections?

OK...this has happened to me more than once so I would like to comment and hopefully receive some feedback. You send in your final revisions for your manuscript and it is accepted by a journal. Sometime later you receive the proofs with the layout for final publication and a request for you to check it over and correct any final typos and/or problems with the layout. You submit your proposed changes within the time alloted and sometime later the manuscript is finally published. Upon reading through the published manuscript you see where some but not all of the changes you requested in the proofs were made, and thus there may still be some annoying errors (typos and/or layout) that you thought were going to be fixed. I am not talking about major changes being requested (which are costly at the proof stage and thus may not be approved by the editors). Instead this is about small corrections that for some reason were not made.

What do you do next? Of course you can contact the editors and point out were requested corrections were not made, but what does this approach get you? An apology and possibly an erratum in the next issue, but does not fix the actual publication (which is now a permanent record). Maybe it is possible to actually proof the proof corrections? I'm not aware of any journal that does this, but I may start asking.

I guess that hypothetically through the writing, review, and rewriting stages all mistakes should have been eliminated, however, anyone who publishes knows that this is not the case. In fact, the proof stage is one of the most important parts of the whole process because it represents the first time the manuscript has been out of the author's control and as I said earlier it represents the permanent record of your work. Wouldn't you like just one last look before it finally does print? I actually had one manuscript a few years back where we did not even get proofs! The final result was not good and we actually felt obliged to add a disclaimer to the reprints and PDFs that we distributed.

Has anyone else had a problem with this? How common is this type of error?

Polish Dragon - Revisited

Back in August I briefly discussed the find of a large theropod and dicynodont from a quarry in Lisowice in southern Poland. This find is significant because it represents the latest stratigraphical unambiguous occurrence of a dicynodont in the Late Triassic, as well as the possible earliest occurrence of a tetnuran theropod. The peer-reviewed article detailing this find is now out in Acta Palaeontologica Polonica.

I still need to read through the paper to comment some more but in the meantime here is the abstract:

It is generally accepted that during the Triassic the composition of tetrapod faunas underwent a series of fundamental transformations, mainly as a result of diversification of
archosaurs and decline of therapsids (Benton 1994, 2004, 2006). The last herbivorous basal synapsids, dicynodonts, disappeared from the record in the early Norian of the
Americas, about 220 Ma (Langer et al. 2007), being unknown from the Late Triassic of Europe. Here, we report a partially articulated skeleton and isolated bones of a giant
rhino−size dicynodont in the Upper Triassic fluvial sediments at Lisowice (Lipie Śląskie clay−pit) in southern Poland. Paleobotanical data indicate an early Rhaetian age for
the fauna (Dzik et al. 2008; Niedźwiedzki and Sulej 2008). The dicynodont bones are associated with bones of carnivorous dinosaurs, pterosaurs, as well as capitosaur and plagiosaur amphibians. Dicynodonts were represented in the Germanic Basin throughout the Late Triassic, as proven by findings of smaller dicynodonts in older deposits in the same area, associated there with temnospondyl amphibians. It appears, thus, that the fossil record of tetrapod succession in the Late Triassic was strongly controlled by ecological factors and biased by uneven representation of particular environments. The Lisowice assemblage proves that faunas dominated by dicynodonts did not entirely disappear at least until the end of the Triassic.

REFERENCE

Dzik, J., Sulej, T., and G. Niedźwiedzki. 2008. A dicynodont−theropod association in the latest Triassic of Poland. Acta Palaeontologica Polonica 53:733–738.

Rethinking Turtle Origins - Odontochelys

What an exciting time it must be to work on basal turtles. Hot on the heels of Chinlechelys and Eileanchelys comes a new basal turtle, Odontochelys semitestacea, from the Norian (~220 Ma) of China. The article and commentary came out today in the journal Nature and you can also read about it here and here.

Odontochelys predates other earliest known turtles by at least 5 million years and is from marine rocks suggesting a marine origin for turtles. The complete fossil (see these photos from the Nature News website), known from four specimens, possesses a ventral plastron but not a dorsal carapace suggesting that the plastron formed first (but see argument by Reisz and Head, 2008).

Finally, as also hinted at by the name, Odontochelys is the first known turtle to possess teeth.

Whereas, the marine origin is surprising given the terrestrial nature of other Triassic turtles overturning what was thought to be a stable hypothesis, the teeth are a nice find, but not so surprising given that turtles must have originated from a toothed reptilian ancestor.

As to the ventral carapace forming first, Reisz and Head (2008) argue against the interpretation provided by Li et al. (2008); however, based on a statement made by Li that "here, in our hands, there is an ideal missing link for turtle evolution. It has no osteoderms on its back, but only ossified neural [central] plates and expanded ribs." I wonder if what we are looking at is a preservational artifact. Maybe the plastron fully ossifies earlier on in ontogeny. Not being a turtle specialist or seeing the specimens I may be completely wrong, but that is the explanation that first popped into my head.

Sounds like there is a lot more exploration and work to be done on basal turtles.

REFERENCES

Chun Li, Xiao-Chun Wu, Olivier Rieppel, Li-Ting Wang, Li-Jun Zhao (2008). An ancestral turtle from the Late Triassic of southwestern China Nature, 456 (7221), 497-501 DOI: 10.1038/nature07533

Robert R. Reisz, Jason J. Head (2008). Palaeontology: Turtle origins out to sea Nature, 456 (7221), 450-451 DOI: 10.1038/456450a

Pseudopalatus jablonskiae

rutgerjansma answered both quickly and correctly. Mystery fossil #3 is the holotype skull of the phytosaur Pseudopalatus jablonskiae named by myself and Randall Irmis in 2006. This skull was collected from the Sonsela Member of the Chinle Formation in Petrified Forest National Park. It was lying palate side up in a path used by archaeologists to access a ruined pueblo on a cliff top. Fortunately, Pat Jablonsky (a long time volunteer at the Denver Museum of Natural History, who was working as a ranger in the park at the time) recognized the specimen in the path and brought it to my attention. Unfortunately, it was pretty badly eroded (and trampled) and only the skull roof was still in-situ. The upper portion of the brain case was able to be reassembled by collecting the float. Preparation showed that it was a pseudopalatine phytosaur; however, it differed from other known pseudopalatines in possessing very anteroposteriorly short squamosal processes (seen in the photo below projecting from the back of the skull). In addition, the squamosal tips were not pointed and 'knob-like' as in other pseudopalatines, but more like the older Leptosuchus. This was supported by a character of the braincase, the entrance of an anterior projection of the squamosal into the lateral wall, another character of Leptosuchus (Camp, 1930). Finally, there is a small fossa around the supratemporal fenestra that is only seen in this specimen (autapomorphy). These characters and discussion with Axel Hungerbuehler (probably THE expert on phytosaurs) made us realize that this specimen was unique. Unfortunately, unique was definitely the right word here, because this incomplete skull is the only known specimen of P. jabloskiae.
However, earlier this summer a trip back to the quarry resulted in the discovery of the lower portion of the braincase of the holotype specimen. It had rolled away from the exposed skull and been buried, surfacing only this year. Subsequently another trip was made to the site to try to find more of the holotype and another, this time complete, skull of a phytosaur was found about 40 meters away and at the same horizon. This specimen has not been prepared yet but preliminary work during the excavation suggests that it may belong to P. jablonskiae. If so this would provide a description of the rest of the skull and further support the taxonomic validity of the species.

One more note. In our 2006 paper we state that P. jablonskiae is from just above the base of the Sonsela Member and therefore represents the lowest occurrence of Pseudopalatus in Petrified Forest National Park. However, reexamination of the Sonsela Member this summer by Jeff Martz figured out that the type locality for P. jablonskiae is higher in the Sonsela than previously believed, and that it occurs just above other localities that have provided specimens of another species of Pseudopalatus, P. pristinus. Thus, the newly recovered skull becomes even more important to test whether or not P. jablonskiae is restricted to a narrow horizon or represents a species that co-existed with P. pristinus.

The full description of P. jablonskiae can be found at Randall Irmis' CV page.

REFERENCES

Camp, C. L. 1930. A study of the phytosaurs with description of
new material from western North America. Memoirs of the University
of California, 10:1-174.

Parker, W. G., and R. B. Irmis. 2006. A new species of the Late Triassic phytosaur Pseudopalatus (Archosauria: Pseudosuchia) from Petrified Forest National Park, Arizona. Museum of Northern Arizona Bulletin 62:126-143.

Late Triassic Mystery Fossil #3

Man I am busy (but aren't we all?), family, two jobs, research, upcoming holidays, and now studying for the GRE (I last took it 11 years ago!). Not too sure what I am thinking at times. Anyhow, I have not done one of these for awhile so here is Late Triassic mystery fossil #3. It comes from the Chinle Formation and is shown here in dorsal view. Hopefully I will post on this fossil and its relatives soon. I also know that there are a few new Triassic papers coming down the pipe soon, so there will be lot to cover in the next couple of months....but for now it is back to the quantitative section study guide.