Allotheria

The Allotheria are a potential taxon ( a systematic group) of extinct mammals. Three groups are summarized in:

• The Haramiyida that lived in the Triassic and the Jurassic and are among the oldest known mammals,
• The Multituberculata, a diverse group that lived from the Jura to the Eocene into the continents of the northern hemisphere and
• The Gondwanatheria that occurred in the southern continents of the Upper Cretaceous to Eocene.

The assumed relationship is based on the construction of the molars, which are in all three groups characterized by a significant arrangement of the cusps. One possible scenario is in the Haramiyida the ancestors of the other two groups, which spread in the Mesozoic and early Cenozoic, but were later displaced by the modern mammals.

The research is complicated but the fact that fossils were hardly known by the Haramiyida and Gondwanatheria long time except scattered teeth. Meanwhile, jaw parts were discovered by two groups, however, the rather argue against a close relationship between these three groups. The Haramiyida have a very primitive Kieferbau while the jaws of Multituberculata and Gondwanatheria more similar to that of present-day mammals. This tends to suggest to see in the Haramiyida an early, unrelated to the other two groups side branch. A detailed cladistic analysis looks a bit more support for this than for the Allotheria theory, but the difference is hardly significant.

Whether Multituberculata and Gondwanatheria in turn are closely related, but is also controversial. It is possible that both groups have developed as an adaptation to similar lifestyles ( small, mostly herbivorous mammal ) only convergent.

The question of whether and to what extent these three groups are closely related, can not be answered at the present time.