A Reminder That Nature Does Not Play Favorites

[airportkid]

THIS is an amazing discovery!  An event that took place over a million years ago preserved by rapid pyroclastic flow, itself an integral dimension of the event.  It's an occurrence so astounding it's forcing re-evaluation of long supposed mammalian behaviors.

[Cavebear]

THIS is an amazing discovery!  An event that took place over a million years ago preserved by rapid pyroclastic flow, itself an integral dimension of the event.  It's an occurrence so astounding it's forcing re-evaluation of long supposed mammalian behaviors.

The link said 125 millions years. "Over a million" seems a bit weak. ')

Mammals are older than most people realize. It is common to think they only arose after the dinosaurs went extinct. In truth, reptiles branched out into into both dinosaurs and mammals at about the same time (225 MYA). At the time, both were large, but the dinosaurs evolved more rapidly. The dinosaurs straight-down hips beat the mammals warmer blood. The mammals became smaller and agile to avoid being eaten. But some were still large enough to attack and eat small dinosaurs. And steal dinosaur eggs.

And they stayed that way for 160 million years. They certainly did evolve, but they became tree-dwellers and burrowers for safety from the dinosaurs. And even when the classic dinosaurs died from the asteroid strike, the mammals did not rule at first. The dinosaurs are not really extinct. Birds are descendants of theropod dinosaurs. And from 65 MYA to about 45 MYA large carnivorous terra-birds ruled.

But isolated North America had no terra birds. It did have mammals. Safe from the terra birds, the NA mammals grew larger and smarter. And the mammals evolved their rib cages to become shorter and allow resting on their sides. Which allowed the females to evolve specific milk-sites (the most ancient females merely oozed a thin milky nutrient through the sweat glands).

Milk is essentially sweat, fat, and some minerals. But it allowed mammals to nurture offspring more successfully for long periods. Larger mammals evolved, some were carnivores. When NA connected with Asia at Alaska/Siberia (Berengia), migration occurred both ways. The NA carnivorous miacids ( big cats, wolves, bears) wiped out the terra birds around 45 MYA.

And that's when the "Age Of Mammals" only truly started.