The ancient mammal Pantolambda bathmodon (illustrated) looked something like a jumbo red panda, with a bearlike head, stocky build and long tail. Despite its fearsome appearance, P. bathmodon was a gentle, plant-eating giant in its ecosystem. H. SHARPE
Science News has a story about early mammals. A mammal nicknamed the ManBearPig" that emerged after the K-Pg mass extinction may help explain how mammals came do dominate the world when the dinosaurs disappeared. The animal was described in a recent paper in the journal Nature.
During the age of the dinosaurs, mammals “only got as large as a domestic cat, maybe, or a badger,” says Gregory Funston, a paleontologist at the Royal Ontario Museum in Toronto. But after an asteroid wiped out all nonbird dinosaurs about 66 million years ago, “we see this huge explosion in mammal diversity, where mammals start to get really big,” Funston says.
In particular, placental mammals got really big. Those are mammals whose babies develop mainly in the womb while fed by a placenta — unlike egg-laying platypuses or marsupials, whose tiny newborns do much of their development in their mother’s pouch. Today, placentals are the most diverse group of mammals and include some of the world’s largest animals such as whales, elephants and giraffes.
Paleontologists have long wondered why placentals rose to dominance. Researchers suspected that the long gestation period of this mammal lineage was an important factor. But it was unclear how long ago such long gestation evolved.
