PermeateFree said:
An interesting read.
>>Recent discoveries highlight how mammals lived before and after the asteroid impact that triggered the world’s fifth mass extinction.
In central Colorado, at a place called Corral Bluffs, there lies an unusual graveyard. The ranks of the dead aren’t filled with people, but animals that lived 66 million years ago. Preserved in hardened concretions of stone lie the remains of turtles, crocodiles, and most of all, mammals that lived in this place during the first million years after the terrible impact that triggered the extinction of the dinosaurs. These animals form a part of our own evolutionary narrative—the story of how mammals went from scurrying around the feet of larger creatures to dominating the continents of the world, evolving into a variety of unique beings, including ourselves.<<
https://www.smithsonianmag.com/science-nature/fossil-site-reveals-how-mammals-thrived-after-death-of-dinosaurs-180973404
> contrary to the standard story of shrew-like critters kept in check by monstrous reptiles, mammals thrived during Mesozoic era. The asteroid impact that felled the “terrible lizards” was also a portentous event for the mammals that had already been plying their own success for tens of millions of years.
Yes. Possibly even longer than tens of millions of years. I like to put it this way, there were primates around as a distinct group before T rex ever came into existence.
> The last common ancestor of all modern mammals lived sometime during the Jurassic, over 160 million years ago.
That’s better, we shouldn’t belittle 94 million years as “tens of millions of years”. Mammals were alive as mammals for more time before the end of the dinosaurs than they have been since the end of the dinosaurs.
> Mesozoic beasts came in many forms. Castorocauda was the Jurassic equivalent of a beaver, complete with a scaly, flattened tail. Volaticotherium, from about the same time, resembled a flying squirrel. Fruitafossor, by contrast, was like a Jurassic aardvark, with powerful limbs that appear well-suited to tearing open termite nests. And the badger-sized Repenomamus was an omnivore that, thanks to fossil stomach contents, we know ate baby dinosaurs. Every year a few more mammal ancestors are added to the list.
> Mammals did not emerge from the extinction event unscathed. Before the asteroid strike, Lyson says, the largest mammals were about the size of a raccoon. Immediately after, the biggest mammals were about rat-sized. But in a world without towering dinosaurs, new opportunities opened for mammals.
> Within 100,000 years after the extinction, we have a different type of raccoon-size mammals,” Lyson says, with additional fossils from Corral Bluffs revealing an increase size over time. By the 300,000-year mark, the biggest mammals were about the size of large beavers, and those that lived 700,000 years after the impact could weigh over a hundred pounds, such as Ectoconus ditrigonus.
Good article. Really enjoyed that, thanks.