Allotheria

Allotheria Temporal range: Late Triassic-Miocene, 153–17.5 Ma PreЄ Є O S D C P T J K Pg N
Skull of Ptilodus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Class:	Mammalia
Subclass:	Theriiformes
Infraclass:	†Allotheria Marsh, 1880
Subgroups
†Camptomus †Fractinus †Gondwanatheria †Haramiyida †Multituberculata

Allotheria (meaning "other beasts", from the Greek αλλός, allos-other and θήριον, therion-wild animal) is an extinct branch of successful Mesozoic mammals. The most important characteristic was the presence of lower molariform teeth equipped with two longitudinal rows of cusps. Allotheria includes Multituberculata, Gondwanatheria (which may be part of Multituberculata, the sister group to Cimolodonta), and probably Haramiyida, though some studies show them to not even be mammals and differing from true allotheres significantly.

Allotheres also had a narrow pelvis, indicating that they gave birth to tiny helpless young like marsupials do.

Interpretations

When he first identified Allotheria in 1880, Othniel Marsh regarded this group as an order within Marsupialia. But in 1997, McKenna and Bell classified Allotheria as an infraclass.

Further reading

Zofia Kielan-Jaworowska, Richard L. Cifelli, and Zhe-Xi Luo, Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure (New York: Columbia University Press, 2004), 249.