Definitions

1. noun

A group of mammals that includes marsupials and their extinct relatives, characterized by the presence of a pouch in the female.

“The study of metatheria is an important area of research in the field of paleontology.”

2. noun

A subclass of theria, a group of mammals that includes marsupials and their extinct relatives.

“The discovery of a new fossil species has shed light on the evolution of metatheria.”