Zalambdalestidae
| Zalambdalestidae | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Turonium to Campanium | ||||||||||||
| 93.9 to 83.6 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Zalambdalestidae | ||||||||||||
| Gregory & Simpson , 1926 | ||||||||||||
The Zalambdalestidae are a family of higher mammals (Eutheria) from the Middle and Upper Cretaceous Period . Apart from the Gobiconodontidae , they included the largest mammals of the Cretaceous period.
features
The skull was about two inches long. The snout was long, mainly due to the elongated maxillary , but also due to a large premaxillary . The cranium was enlarged and the region between the palate and the capsule of the inner ear shorter than in Asioryctitheria , but longer than in modern mammals. The cerebellum was short and wide. The neocortex may have been very small.
The tooth formula is different, but shows a trend towards reducing the number of teeth, as with the glires ( rodents and rabbits ). The central lower incisors were large, rootless, and grew back a lifetime. Only the front and the crowns were covered with enamel.
The postcranial (behind the skull) skeleton largely corresponded to that of the recent elephants (Macroscelididae). Extended hind legs and metatarsals suggest a hopping locomotion. The shin and fibula had grown together. The intercenter of the atlas had fused with the neural arch. A separate coracoid or interclavicle , a bone between the collarbones , is missing.
Kielan-Jaworowska suspected that the Zalambdalestidae lived in rocky habitats and that their protruding incisors pulled insects out of caves and gaps in the rock. Due to the presumably good sense of hearing and smell , it is assumed that the Zalambdalestidae were nocturnal.
Systematics
As the closest relatives of the Zalambdalestidae, the Asioryctitheria , another group of Asian mammals from the Cretaceous period, and / or the Glires ( rodents and rabbits ) are considered. The main characteristics for the suspected relationship are the structure and arrangement of the teeth. However, some scientists argue that the structure of the teeth of the Zalambdalestidae could also have converged to that of the Glires.
Genera
literature
- Thomas S. Kemp: The Origin & Evolution of Mammals. Oxford University Press, Oxford 2005, ISBN 0-19-850761-5 .
- Kenneth D. Rose, J. David Archibald (Eds.): The rise of placental mammals. Origins and relationships of the major extant clades. Johns Hopkins University Press, Baltimore MD et al. 2005, ISBN 0-8018-8022-X .
Web links
- The Paleobiology Database: Zalambdalestidae