Bystrowianidae

Bystrowianidae
	Bystrowiana from the Upper Permian of Russia.
Temporal occurrence
	Upper Permian to Middle Triassic
	approx. 260 to 230 million years
Locations
	European Russia, China, Southern Germany;
Systematics
	Vertebrates (vertebrata)
	Jaw mouths (Gnathostomata)
	Land vertebrates (Tetrapoda)
	Reptiliomorpha
	Chroniosuchia
	Bystrowianidae
Scientific name
	Bystrowianidae
	Vyushkov , 1957
Genera
	Bystrowiana; Axitectum; Dromotectum; Synesuchus; Bystrowiella;

The Bystrowianidae are a group of reptiliomorphic terrestrial vertebrates that has only been documented by a few fossil finds . They were discovered in continental sedimentary rocks of the Upper Permian of Russia and China as well as the Triassic of Russia and Germany and were named after the Russian vertebrate paleontologist Alexei Petrovich Bystrov . While other groups of reptiliomorphic amphibians died out at the end of the Permian, the Bystrowianids with the relic forms Synesuchus and Bystrowiella extend into the Middle Triassic.

features

With the exception of Bystrowiana , Bystrowianids are almost exclusively occupied by vertebrae and cutaneous bone plates ( osteoderms ), so that these have so far provided the only osteological characteristics for differentiating between Bystrowianid genera and species (Novikov & Shishkin 2000, Novikov et al. 2000).

The vertebral structure, characterized by pleurocentres concave on both sides, which are fused with the neural arches , and intermediate disc-shaped to spherical intercentres, is essentially similar to that of the sister group Chroniosuchidae . A special feature of the Bystrowianids are a pair or more pairs of paraneural canals that lie within the neural arch to the side or above the actual spinal canal and can be just as voluminous (cf. Novikov et al. 2000). Their function is unclear; their shape may be related to the development of the epaxial muscles (Golubev 1998).

In contrast to some Chroniosuchidae, the back osteoderms are always narrow and are unlikely to have acted as protective armor. They show an abdominal extension with an oval cross-section, which is always fused with the spinous process of the associated vertebra. Although both groups show a complicated articulation between two plates, Golubev (1998) considers the comparability of such structures in Chroniosuchidae and Bystrowianidae to be problematic. Novikov & Shishkin (2000), on the other hand, homologate the flat fore wings ( ala anterior ) and the posterior articular plate ( lamina articularis ) of the Bystrowianids with the forward and backward pointing processes of the Chroniosuchid osteoderms.

Systematics

After their initial classification in the Kotlassioidea or Kotlassiomorpha, which are considered a subgroup of the Seymouriamorpha (Vyushkov 1957, Tatarinov 1972), since the revision by Ivakhnenko & Tverdokhlebova (1980), Bystrowianids have been assigned to the Chroniosuchia ( syn.Chroniosuchida) together with the Chroniosuchida .

Genera and species of Bystrowianidae described so far:

Bystrowiana permira Vyushkov, 1957
Bystrowiana sinica Young, 1979
Axitectum vjushkovi Novikov & Shishkin, 1992
Axitectum georgi Novikov & Shishkin, 2000
Dromotectum spinosum Novikov & Shishkin, 1996
Synesuchus muravjevi Novikov & Shishkin, 1996
Bystrowiella schumanni Witzmann, Schoch & Maisch, 2008.

literature

Golubev, VK (1998). Narrow-armored Chroniosuchians (Amphibia, Anthracosauromorpha) from the Late Permian of Eastern Europe. Paleontologicheskij Zhurnal 1998 (3): 64-73.
Ivakhnenko, MF, GI Tverdokhlebova (1980). Systematics, Morphology, and Stratigraphic Significance of the Upper Permian Chroniosuchians from the East of the European Part of the USSR. Saratov, Izdatelstvo Saratovskogo Universiteta.
Novikov, IV, Shishkin MA (1996). Paleozoic relics in the Triassic tetrapod communities: the last anthracosaurian amphibians. Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota., Beijing, China Ocean Press.
Novikov, IV, MA Shishkin, VK Golubev (2000). Permian and Triassic anthracosaurs from Eastern Europe. In: MJ Benton, MA Shishkin, DM Unwin, EN Kurochkin (ed.), The Age of Dinosaurs in Russia and Mongolia, Cambridge, Cambridge University Press: 60-70.
Tatarinov, LP (1972). Seymouriamorphs from the fauna of the USSR. In: O. Kuhn (ed.), Encyclopedia of Paleoherpetology, vol. 5B, Stuttgart (Gustav Fischer), 80 pages.
Vjushkov, BP (1957). New kotlassiomorphs from the Tatarian Series in the European part of the USSR. Upper Permian cotylosaurs and batrachosaurs from the SSSR. BP Vyushkov. Moscow, Trudy Paleontologicheskogo Instituta Akademya Nauk SSSR: 89-107.
Witzmann, F., RR Schoch, MW Maisch (2008). A relic basal tetrapod from the Middle Triassic of Germany. Science 95 (1): 67-72.
Young, CC (1979). A new Late Permian fauna from Jiyuan, Honan. Vertebrata Palasiatica 17: 99-113.