Amphilestidae
| Amphilestidae | ||||||||||||
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Life picture of Gobiconodon |
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| Temporal occurrence | ||||||||||||
| Middle Jura to Upper Jura | ||||||||||||
| 165 to 150 million years | ||||||||||||
| Locations | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Amphilestidae | ||||||||||||
| Osborn , 1888 | ||||||||||||
The Amphilestidae are a group of extinct mammals (Mammalia) that lived in the Middle and Upper Jurassic .
features
The Amphilestidae like some other Mesozoic mammals (which are summarized as Eutriconodonta ), characterized by three cusps arranged one behind the other on each molar (molar). In contrast to the Triconodontidae , however, the middle cusp is significantly larger than the other two and the groove-like connection between the molars is missing. Amphilestes , the genus that gives it its name, is thought to have had four incisors , one canine , four premolars and five molars in the lower jaw per half of the jaw . Apart from teeth and jaw parts, no findings of these animals are known, but the findings suggest a carnivorous way of life.
Systematics
The sparse fossils make it difficult to define the Amphilestidae precisely and classify them systematically. A three-humped structure of the molars is also known from numerous other Mesozoic mammals, whether these animals represent a natural group ( eutriconodonta ) or merely convergent developments is disputed. 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.
Only the genera Amphilestes and Phascolotherium , which both lived in the Middle Jurassic and were discovered by Richard Owen in England , are undoubtedly closely related . Other genera that are reserved in this group are Aploconodon , Comodon and Triconolestes (all from the Upper Jurassic of North America ), Liaotherium (from the Central Jurassic of China ) and Tendagurodon , which was discovered in Tendaguru ( Tanzania ) and could be a sign of this that these animals were also widespread in the former southern continent of Gondwana .
literature
- Thomas S. Kemp: The Origin & Evolution of Mammals. Oxford University Press, Oxford 2005, ISBN 0-19-850761-5 .