Amphitheriida
Encyclopedia
Amphitheriida is an order of mesozoic mammals restricted to the Middle Jurassic
of Britain
. They were closely related to the Dryolestids
but possessed five molars instead of the usual four in Dryolestida, (with the exception of the family
Dryolestidae
whose members possessed between 8 and 9 molars). The Amphitheriida contains one family, the Amphitheriidae.
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
of Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
. They were closely related to the Dryolestids
Dryolestida
Dryolestida is an extinct order of mammals known from the Jurassic to Tertiary. It has been suggested that these mammals are either the possible ancestors of therian mammals or an offshoot from the same evolutionary line. It is also believed that they developed a fully mammalian jaw and also had...
but possessed five molars instead of the usual four in Dryolestida, (with the exception of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Dryolestidae
Dryolestidae
Dryolestidae was an abundant and diverse group of Mesozoic mammals. These mammals were different from their relatives by having the following two characteristics:*Their upper and lower molars were shortened mesiodistally and widened labiolingually....
whose members possessed between 8 and 9 molars). The Amphitheriida contains one family, the Amphitheriidae.