What is mammaliaformes?

Mammaliaformes is an extinct group of mammal-like animals that lived during the Late Triassic to the Late Cretaceous period, approximately 225 to 70 million years ago. They are considered to be the closest relatives of modern mammals and are also known as stem mammals or proto-mammals.

Mammaliaformes have a few characteristics that set them apart from other reptiles of their time, such as the presence of a dentary-squamosal jaw joint and a more complex bony structure in their ear, similar to that of modern mammals. They also had forward-facing eyes and agile limbs, giving them a more efficient running gait.

The group includes several distinct subgroups, such as the triconodonts, multituberculates, and symmetrodonts. These animals varied greatly in size, from small shrew-like creatures to larger forms that resembled modern herbivorous mammals.

Mammaliaformes went through a period of diversification during the Jurassic and Cretaceous periods, with some groups, such as multituberculates, becoming a dominant group of small-bodied mammals during the Mesozoic era. However, they were eventually outcompeted by other groups, such as placental mammals, which emerged during the Cenozoic era.

Fossils of mammaliaformes have been found in various parts of the world, including North America, Europe, Asia, and South America. They are important to the study of mammalian evolution and provide valuable insight into the origins of modern mammals.