Trechnotheria

Trechnotheria is a group of mammals that includes the therians and some fossil mammals from the Mesozoic Era. In the Jurassic through Cretaceous periods, the group was only found in the area which is now modern Asia and Africa.^[2]

Trechnotheria Temporal range: Late Triassic - Holocene, 216.5–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Kangaroo with her joey
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Clade:	Theriiformes
Clade:	Trechnotheria McKenna, 1975
Subgroups[1]
†Spalacotheriida †Spalacotheriidae †Zhangheotheriidae Cladotheria †Dryolestida Zatheria (including modern therians)

When the group Trechnotheria was first defined, it was said to be a "superlegion". Since then it has been given many different ranks.^[3] Later, a definnition based on nodes was created for Trechnotheria. This clade was imcluded the last common ancestor of Zhangheotherium and living therian mammals and all of its descentants.^[4]

Characteristics

Like most mammal groups from the Mesozoic Era, early trechnotherians are known mainly from their teeth. One of the features of this group which is the most noticable is their large teeth. The features of the shoulder blade, tibia, humerus, and ankle joint are also used to define which animals are in this clade.^[1]

Related pages

• Allotheria