Gliselle Marin joins the “Bat-a-thon,” a group of 80-some bat researchers who converge on Belize each year to study these winged mammals.

The snake-like amphibian is native to Brazil. Researchers say the milk in many ways resembles that produced by mammals.

A 125-million-year-old fossil from the early Cretaceous shows the skeletons of a smaller mammal biting a larger horned dinosaur, suggesting a much more complex ancient food web.

Researchers have examined the genomes of 240 mammal species. The project reveals when mammals evolved, how some developed the ability to hibernate, and clues that may help explain humans' brains.