From the chaotic aftermath of a massive asteroid impact sprang the mother of all placental mammals — the most recent common ancestor of everything from monkeys to whales to sloths. Not until at least 200,000 years after a giant space rock smashed into the Yucatan and obliterated the dinosaurs was the small, furry critter scurrying around, eating insects and birthing hairless young. This timing, based on a large study of mammalian physical characteristics and reported today in Science, suggests that the placental tree of life began sprouting its many branches about 36 million years later than genomic clocks indicate.
Scientists reached this conclusion after making 4,541 measurements of characteristics such a hair type, wings, and brain structures in 86 species, living and extinct. Combining those observations with molecular data helped the team reconstruct a mammalian tree pointing toward the last common ancestor of all mammals. Then they generated an image of what such an animal might have looked like, based on comparisons of characteristics shared by closely related species. The result critter is a long-tailed, rat-size furball that resembles both a mouse and a shrew — and perhaps luckily for it, it didn’t have to contend with too many giant reptiles.
After the Dinosaurs Died This Furball Started the Next Big Thing
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After the Dinosaurs Died This Furball Started the Next Big Thing
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After the Dinosaurs Died This Furball Started the Next Big Thing
