Cartorhynchus
| Cartorhynchus | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Triassic ( Olenekian : Spathium ) | ||||||||||||
| 251.2 to 247.2 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Cartorhynchus | ||||||||||||
| Motani et al., 2014 | ||||||||||||
Cartorhynchus lenticarpus is an extinct Triassic reptile that was related to the ancestors of the ichthyosaurs . It was found near the old town of Chaohu in eastern China. The Latin name indicates the short snout ( Cartorhynchus ) and the flexible wrist ( lenticarpus ).
features
The holotype of Cartorhynchus lenticarpus is only preserved with a length of 21.4 centimeters, whereby the original total length is estimated at 40 centimeters. Since the degree of ossification indicates a fully grown animal, Cartorhynchus is the smallest known ichthyosaur relative.
skull
The snout is toothless and pointed and makes up about half of the total length of the skull. The intermaxillary bone is elongated and the nasal bone extends to the tip of the snout. The nostrils are far back. The eye is not noticeably enlarged and shows little adaptation to underwater vision. The lower jaw is strong and the hyoid bone is very large. The pineal foramen is very large.
hull
The Cartorhynchus axillary skeleton is very strong. In total there are 31 vertebrae in front of the sacrum , 5 of which appear to be cervical vertebrae , significantly fewer than the usual 40 to 80 vertebrae of real ichthyosaurs. The ribs are solidly built so that the gaps between the ribs in the front part of the body are narrower than the ribs. The abdominal ribs are not fused in the center. The shoulder blade is wider distally than proximally . The interclavicle is cruciform.
The front limbs are strongly arched back, the rear limbs bent forward. There is a large gap between the zygopodium and metapodium , which indicates that cartilage elements in the tarsus have not been preserved . Only three toes on the forelegs are ossified.
Way of life
Cartorhynchus seems to be far less adapted to an aquatic way of life than later ichthyosaurs. The number of vertebrae is lower, the snout is short and the limbs seem to have allowed waddling on land in addition to swimming. It has therefore been suggested that Cartorhynchus may have lived amphibiously .
Systematics
In the first description was cartorhynchus made on the basis of the Ichthyosaurs, wherein the two taxa Ichthyosauriformes (for all forms detail with ichthyosaurus communis than Hupehsuchus nanchangensis are used) and Ichthyosauromorpha (for the last common ancestor of ichthyosaurus communis and nanchangensis Hupehsuchus and all its descendants) were newly proposed:
| Ichthyosauromorpha |
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literature
- Ryosuke Motani, Da-Yong Jiang, Guan-Bao Chen, Andrea Tintori, Olivier Rieppel, Cheng Ji, Jian-Dong Huang: A basal ichthyosauriform with a short snout from the Lower Triassic of China . In: Nature . 2014, doi : 10.1038 / nature13866 (online article preview).