Laurasiatherian

Laurasiatherians are a group of mammals that evolved during the Paleogene and Neogene periods, roughly 66 to 2.6 million years ago. They are characterized by their distinctive dental and skeletal features, which have been used to define the group. Laurasiatherians are believed to have originated in Asia and later spread to North America, Europe, and Africa. This group includes a diverse range of mammals, such as primates, carnivorans, perissodactyls, and artiodactyls. The term "Laurasiatheria" was coined by paleontologist George Gaylord Simpson in 1945, who recognized the unique evolutionary history and shared characteristics of these mammals. Despite their diversity, laurasiatherians share several key traits, including a reduced number of upper incisors, a more complex lower jaw, and a unique pattern of tooth replacement. The group's evolution is marked by significant adaptations to various ecological niches, reflecting their widespread distribution and ecological success.