Sonntag, 28. Juni 2009

Chroniosuchians and stay in Moscow

To resolve the riddle: The bonified eyeball from the last post represents a a ball-shaped intercentrum of a chroniosuchid from the Permian of Russia.

In chroniosuchian reptiliomorphs the intercentra (white arrows) are interlocked with the amphicoelous pleurocentra in a ball-and-socket-like fashion. The image on the left shows some section of a Chroniosuchus vertebral column in ventral view. Intercentra become bony balls only in the adult individuals - not fully bonified in sub-adults and juveniles they are preserved with a crescent, disk-like or ellipsoidal shape.

Also, the fusion of the neural arch with the pleurocentrum - a feature otherwise characteristic for "higher reptiliomorphs" such as seymouriamorphs and diadectomorphs - is only completed in the course of ontogenesis (so that you can find suture lines in the subadult individuals).

Moscow: Paleontological Institute and Museum of the Russian Academy of Sciences (PIN)

The paleo-style PIN building has a castle-like rectangular shape with an inner courtyard featuring life-size sculptures of fossil critters from Russia and areas of the former Soviet Union. The exhibition has almost everything you wish for as a vertebrate enthusiast (here depicted: the two-story dinosaur hall). Rich in type specimens the collection is essential for some and important for many studies - so earlier or later many of the fossil vertebrate people spend some time there.

Concering the Chroniosuchia: With the exception of bystrowianid chroniosuchian remains from Kupferzell, Germany (Witzmann et al. 2008) and China (Young 1979) and some rather questionable Chinese chroniosuchid chroniosuchians (Li & Cheng 1999), all yet described Permian and Triassic chroniosuchian taxa come from the European part of Russia and are mostly archived in the PIN. I am thankful to Valery Golubev who helped me a lot during my week of stay when I was studying the type materials and to Jury Gubin who nicely put up with me in his room.

Some literature on chroniosuchians

Here considered: titles also available in English (plus the Chinese ones mentioned above).

Golubev, V. K. (1998).
"Narrow-armored Chroniosuchians (Amphibia, Anthracosauromorpha) from the Late Permian of Eastern Europe." Paleontologicheskij Zhurnal 1998(3): 64- 73. [Russian, English]

Golubev, V. K. (1998). "Revision of the Late Permian chroniosuchians (Amphibia, Anthracosauromorpha) from Eastern Europe." Paleontologicheskij Zhurnal 1998(4): 68- 77. [Russian, English]

Golubev, V. K. (1999).
"A new narrow-armored chroniosuchian (Amphibia, Anthracosauromorpha) from the Late Permian of the East Europe." Paleontologicheskij Zhurnal 1999(2): 43- 50. [Russian, English]

Li, J., Cheng Z. (1999). " New anthracosaur and temnospondyl amphibians from Gansu, China." Vertebrata PalAsiatica 37(3): 234- 247. [Chinese with English abstract]

Novikov, I. V., M.A. Shishkin (2000). "Triassic chroniosuchians (Amphibia, Anthracosauromorpha) and the evolution of the trunk dermal ossifications in the bystrowianids." Paleontological Journal 34(supplement): S165- S178. [English]

Novikov, I. V., M.A. Shishkin, V.K. Golubev (2000). Permian and Triassic anthracosaurs from Eastern Europe. The Age of Dinosaurs in Russia and Mongolia. M. A. S. M.J. Benton, D.M. Unwin, E.N. Kurochkin. Cambridge, Cambridge University Press: 60- 70. [English]

Witzmann, F., R.R. Schoch, M.W. Maisch (2008). "A relic basal tetrapod from the Middle Triassic of Germany." Naturwissenschaften 95(1): 67- 72. [English]

Young, C. C. (1979). "A new Late Permian fauna from Jiyuan, Honan." Vertebrata Palasiatica 17: 99- 113. [Chinese with English abstract]

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