Triconodontidae
| Triconodontidae | ||||||||||||
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Lower jaw of Triconodon |
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| Temporal occurrence | ||||||||||||
| Upper Jurassic to Upper Cretaceous | ||||||||||||
| 75 to 150 million years | ||||||||||||
| Locations | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Triconodontidae | ||||||||||||
| Marsh , 1887 | ||||||||||||
The Triconodontidae are a group of extinct mammals (Mammalia) that lived in the Upper Jurassic and the Cretaceous Period . Fossil finds are known from Europe and North America.
description
Like some other Mesozoic mammals (which are summarized as Eutriconodonta ) the Triconodontidae are characterized by three cusps arranged one behind the other on each molar (molar). It is characteristic of the Triconodontidae that these three cusps are approximately the same size and that a bead of tooth enamel ( cingulum ) is present on the tooth neck . An additional cusp at the rear end of each lower molar fitted into a recess on the front of the next molar, providing additional stability when biting. Except for teeth and jaw parts, however, there are hardly any fossils of this group. Only Triconodon was found to have a full, eight centimeter long lower jaw, which suggests that the animal was roughly the size of a gorse cat . The structure of the teeth suggests carnal food.
External system
The Triconodontidae are classified into the group of Eutriconodonta with some other taxa, which also have a three-humped structure of the molars . However, whether these groups are really closely related or have only developed convergently is a matter of dispute. Their position in the mammalian system is also unclear, but it is likely to have been a relatively early, specialized branch. They are not closely related to today's mammals.
Internal system
A number of genera have been described that were discovered in Europe (mainly in the Upper Jurassic ) and North America (mainly in the Lower and Middle Cretaceous Period ). The first genus found was Triconodon from England; Richard Owen described them in 1859. Other genera are Alticonodon , Arundelconodon , Astroconodon , Corviconodon , Jugulator , Priacodon and Trioracodon .
literature
- Thomas S. Kemp: The Origin & Evolution of Mammals . Oxford University Press, Oxford 2005, 331 pages, ISBN 0-19-850761-5 .