Procolophonoidea
| Procolophonoidea | ||||||||||||
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Sclerosaurus in a live reconstruction |
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| Temporal occurrence | ||||||||||||
| Upper Perm to Upper Triassic | ||||||||||||
| 260 to 199.6 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Procolophonoidea | ||||||||||||
| Seeley , 1888 |
The Procolophonoidea are an extinct group of parareptiles that lived for about 60 million years from the Upper Permian to the Upper Triassic and produced a considerable wealth of species during the Triassic. Fossil evidence has been found on most of the continents (except for South America and Australia).
Anatomical features
skull
A characteristic feature of the skull of the group is an eye socket that is more or less enlarged behind the eye . In the anapsid procolophonoid, this pseudo-skull window widened the anchoring of the jaw muscles. A large indentation in the quadratum and the narrow stapes in the middle ear suggest the presence of an eardrum (tympanum), which would have enabled the procolophonoidea to hear high frequency sounds.
The early Procolophonoidea had a thin skullcap and numerous small, needle-like teeth. Procolophon from the Lower Triassic of South America and Antarctica was 30 to 40 centimeters long, later forms became much larger and had an enlarged skull that was thickened in various places. Horn-like spines on the square jugals of the back of the head and the lower cheek region may have served as a defense. The number of laterally broadened teeth of these later species is small. The blunt, peg-like molars came when biting the occlusion , probably an adaptation to fiber-rich plant foods but also the consumption of arthropods (Arthropoda) with well-developed cuticle seems possible with this dentition.
Body skeleton
The postcranial (= behind the skull) skeleton of the animals is primitive. The legs protruding sideways made it possible to crawl. The attachment of the pelvis is reinforced by a third sacral rib. The neural arches of the vertebrae are dilated. The widened feet suggest a certain burial activity.
Systematics
The systematic position of the procolophonoid has not been conclusively clarified. In the past they were regarded as a group close to the reptiles, today the group is considered to be the parareptiles . Their position within this reptile group is the subject of scientific debate, some consider them to be the closest relatives of the turtles , while others believe that this applies to the Pareiasauridae .
literature
- Robert L. Carroll : Paleontology and Evolution of the Vertebrates. Thieme, Stuttgart et al. 1993, ISBN 3-13-774401-6 .
- Introduction to Procolophonoidea .
- Michael J. Benton : Paleontology of the vertebrates. Translation of the 3rd English edition by Hans-Ulrich Pfretzschner. Publishing house Dr. Friedrich Pfeil, Munich 2007, ISBN 978-3-89937-072-0 .
Web links
- Procolophonoidea at Palæos
- University of California Museum of Paleontology: Introduction to Procolophonoidea