Seymouria
| Seymouria | ||||||||||||
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Live reconstruction of Seymouria baylorensis |
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| Temporal occurrence | ||||||||||||
| Unterperm | ||||||||||||
| 284 to 272.5 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Seymouridae | ||||||||||||
| Williston, 1911 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Seymouria | ||||||||||||
| Broili , 1904 | ||||||||||||
Seymouria was a terrestrial vertebrate that iscounted amongthe so-called reptiliomorphic amphibians. Fossils of the animals were found in the central southwest of the United States and in the Bromacker in Tambach-Dietharz in the Thuringian Forest . The genus was named after Seymour , Texas , where Seymouria was first found. Some skeletons are preserved in three dimensions, making Seymouria the best-studied species of Seymouriamorpha . All fossils come from adult animals, remains of the larvae are not known. Seymouria lived in the semi-deserts of the Lower Permian and was likely to be relatively common.
features
Seymouria reached up to sixty centimeters in length and, thanks to its relatively long, powerful limbs, could raise the body higher above the ground than more primitive land vertebrates. The legs were well ossified, while the distal leg end of most of the other Seymouriamorphs was still cartilaginous. The femur and humerus bones were sturdy. Seymouria had five toes on each foot. The front legs were shorter than the rear legs. Their proximal and distal ends were greatly enlarged in order to offer the muscles large attachment surfaces. The broad vertebral arches were firmly fused with the vertebral centers. Bone sutures are not visible. Scales were not found. It is therefore not known whether Seymouria was scaly.
The well-examined skull had a small temporal window at the back of the head that offered space for blood vessels and nerves. The two wing legs were not separated and formed a closed palate. The middle ear probably had an eardrum, and a well-preserved stapes transmitted the sounds to the inner ear. Notches in the anteroventral and posteroventral edge of the eye socket were not found in other Seymouriamorphs and may be an autapomorphism of Seymouria .
species
Three types have been described:
- Seymouria baylorensis is the type species of the genus. All fossils of the species were found in Texas.
- Seymouria sanjuanensis is known from Utah , New Mexico and Germany.
- Seymouria grandis is known for fragmentary remains from Oklahoma and Texas.
Systematics
The group of Seymouriamorpha belongs to the mosaic forms and combines characteristics of amphibians and reptiles . But it is more closely related to today's reptiles than to the Lissamphibia , today's amphibians.
literature
- Michael J. Benton : Paleontology of the vertebrates. 2007, Friedrich Pfeil Verlag, ISBN 3899370724
