Welcome to the mammalverse: Scientists sequence DNA from 240 species around the world

Even before the reign of the dinosaurs ended in a mass extinction event about 65 million years ago, mammals had already gotten a humble but solid foothold.

That's just one of the findings from a close examination of DNA from 240 different mammalian species, an ambitious effort to understand how hairy, milk-producing mammals — including humans — evolved to have such an astonishing array of sizes, shapes, and special abilities.

Scientists know of around 6,500 living mammal species, inhabiting practically every environment on Earth — from frigid oceans to high deserts. This international project, called Zoonomia, set out to collect genetic material from across the entire mammalian family tree.

Researchers obtained DNA from all kinds of mammalian critters, like caribou, armadillos, bats, and bison. Their genetic menagerie eventually included 52 endangered species, like the giant otter and the Amazon river dolphin, as well as primates like chimps and humans.

"We're still only looking at a tiny portion of mammals, but it is the largest project we've ever done like this," says Elinor Karlsson, director of the Vertebrate Genomics Group at the Broad Institute of MIT and Harvard, who notes that 80 percent of the mammalian families are represented in their collection.