Cladotheria

Cladotheria is an extinct clade of metatherian mammals that lived during the Cretaceous and Paleogene periods. They are considered to be a primitive group of therians, closely related to modern marsupials and placentals. Fossil evidence suggests that cladotherians possessed a mosaic of primitive and derived features, offering insights into early mammalian evolution. Key characteristics often include a tribosphenic molar pattern, a hallmark of therian mammals, but with variations that distinguish them from later groups. Their dentition is particularly important for understanding their diet and evolutionary relationships.

The geographic distribution of cladotherians was widespread, with fossils found on multiple continents, indicating a significant presence in ancient ecosystems. They inhabited diverse environments, from terrestrial forests to more open landscapes. The evolutionary trajectory of cladotherians is complex, with various lineages appearing and disappearing throughout the Mesozoic and early Cenozoic eras. Some cladotherian groups may have been direct ancestors or close relatives of the earliest marsupials and placentals, while others represent a separate evolutionary branch that eventually died out. Studying cladotherians helps scientists reconstruct the early diversification of mammals and understand the origins of the mammalian orders we see today.