A newly found fossil of an extinct mammal relative and her 38 babies is among the best evidence that a key development in the evolution of mammals. Compared with the rest of the animal kingdom, mammals have the biggest brains and produce some of the smallest litters of offspring.
The study, published in the journal Nature chronicles the findings of the research team from The University of Texas at Austin. The mammal relative belonged to an extinct species of beagle sized plant eaters called Kayentatherium wellesi that lived alongside dinosaurs about 185 million years ago. Like mammals, Kayentatherium probably had hair.
A critical step in the evolution of mammals was trading big litters for big brains, and that this step happened later in mammalian evolution. The mammalian approach to reproduction directly relates to human development including the development of our own brains.