Chroniosuchidae
Chroniosaurus dongusensis from the Upper Permian of Russia.
- European Russia,? , China, Kyrgyzstan
- Chroniosuchus
- Chroniosaurus
- Uralerpeton
- Jarilinus
- Suchonica
- Madygenerpeton
The Chroniosuchidae were a group reptiliomorpher land vertebrates of the Upper Permian of Russia, their representatives, given their frequent occurrence in Seesedimentgesteinen probably aquatic or amphibious lived and acted in freshwater lakes as crocodile -like predators - a similar ecological position, as they held some groups of large Temnospondylier until the occurrence of archosaurs ( Sennikov 1996).
Features
The majority of the known forms show a segmented carapace, consisting of a series of hinged together a broad skin bony plates ( osteoderms ). Chroniosuchiden so take the subsequent formation of similar armor in amniotes as the Crocodylomorphen, Aetosauriern, ankylosauruses and armadillos anticipated.
Uralerpeton and Suchonica show demhingegen relatively narrow osteoderms, but among other things, in the formation of a pair of rear facing articulation surfaces and an elongated pi -shaped ventral process, which represents the connection to the spinous process of the corresponding vertebra, the osteoderms other Chroniosuchiden same ( Golubev 1998-1999).
Similar to other terrestrial vertebrates of the Paleozoic was the belly side of the body with a system of partly ossified spindle scales occupied ( Ivakhnenko & Tvedokhlebova 1980). In their vortex structure same Chroniosuchiden the sister group Bystrowianidae, the amniotes and some other Reptiliomorphen as the Diadectomorpha and Seymouriamorpha is that the vertebral arch is fused to the Pleurocentrum (see Novikov et al., 2000).
Converging on the Antorbitalfenster the archosaurs have Chroniosuchiden on a skull opening between the eye and nostril. The contact surfaces of involved cranial bones show that the upper jaw and cheek were movable relative to the skull roof - the skull could be widened or narrowed laterally in this form of Schädelkinese. Between the Tabularhörner of the occiput to the front Osteoderm the back plate series a ( Ivakhnenko & Tverdokhlebova 1980, Golubev 2000) fit.
System
Since the revision of Ivakhnenko & Tverdokhlebova (1980 ) the Chroniosuchiden be consolidated with the Bystrowianiden in the group Chroniosuchia and are considered relatives of the Anthracosauria.
According to the redescription of the Russian Chroniosuchiden material by Golubev (1998 - 2000) and according to a method described in 2010 from the Fund Madygen formation southwest of Kyrgyzstan following genera and species are valid:
- Chroniosuchus paradoxus Vyushkov, 1957
- Chroniosuchus licharevi Ryabinin, 1962
- Chroniosaurus dongusensis Tverdokhlebova, 1972
- Chroniosaurus levis Golubev, 1998
- Uralerpeton tverdokhlebovae Golubev, 1998
- Jarilinus mirabilis Golubev, 1998
- Suchonica vladmiri Golubev, 1999
- Madygenerpeton pustulatus Schoch, Voigt & book joke, 2010
Based on an upper jaw and a lower jaw fragment from the Upper Permian of China another genus and species were described and the Chroniosuchiden asked each: Phreatochronis qilianensis and Ingentidens corridoricus ( Li & Cheng 1999).
Importance for the stratigraphy of the Russian platform
Chroniosuchiden used in addition to other terrestrial vertebrates as key forms for biostratigraphic subdivision of the continental sedimentary sequences of the Russian Central to Upper Permian (Table based on Golubev 2000).
- Uralerpeton tverdochlebovae
- Bystrowiana permira
- C. paradoxus
- C. licharevi
- J. mirabilis
- C. levis
- C. dongusensis
- Suchonica vladimiri