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On the Procompsognathus postcranium

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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.

4 comments:

  1. I should add that I do not agree with the ID of SMNS 12591a as dinosaurian. In the drawing of the specimen provided by Sereno and Wild (1992)you can clearly see in dorsal view the emargination of the posterior portion of the frontal by the supratemporal fossa. This is a characteristic of basal crocodylomorphs and thus supports the ID provided by Sereno and Wild (1992).

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  2. It really was a historical summary and not new research. The supertree doesn't say anything better about what Procompsognathus is than any of the studies that generated it (and in fact is by definition worse than the best study it incorporated). Also, since Chatterjee's and Allen's work remains unpublished, the authors couldn't examine their evidence to evaluate their claims.

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  3. I agree with you Bill that SMNS 12591a is not a dinosaur skull. But, extention of the supratemporal fossa onto the frontal is found in both dinsaurs and crocodylomorphs. See character 20 of Novas (1996) in JVP.

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  4. Randy,
    You are correct of course. The condition in SMNS 12591a is more similar to that in basal crocodylomorphs, which is what I was attempting to point out, although quite poorly. Thanks for straightening me out.

    Mickey,

    Excellent points.

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