Asioryctitheria is an extinct order of early eutheria

Eutheria

Eutheria is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals than to living marsupials . They are distinguished from noneutherians by various features of the feet, ankles, jaws and teeth...

ns.

Skull structure

With the exception of Prokennalestes, these advanced forms lacked a Meckelian groove

Meckelian groove

The Meckelian groove is an opening in the medial surface of the mandible which exposes the Meckelian cartilage....

. Furthermore they were equipped with double-rooted canine

Canine tooth

In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...

s, a lower premolar

Premolar

The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...

 with a reduced or absent metaconid and a more elongated lower premolar than their predecessors. In addition, the entoconid and hypoconulid on the lower molars are untwinned, the entotympanic is non-existent, the alisphenoid is enlarged, a Vidian foramen is present as well as a promontorium linked to the paroccipital process via the crista interfenestralis

Crista interfenestralis

The crista interfenestralis is anatomical feature that separates the inner ear in two, it is found in some reptiles.-External links:*...

.

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), 499-501.

External links

• MESOZOIC MAMMALS; Basal Eutheria Two, an internet directory
• A eutherian mammal from the Early Cretaceous of Russia at Ingenta