What hat does a mouse have in common with a cartilaginous fish known as a little skate?

At first glance, you might think not much. One’s fluffy, with big ears and whiskers; the other breathes with gills and ripples its way around the ocean. One is a lab animal or household pest; the other is most likely to be seen in the wild, or the bottom of a shallow pool at an aquarium.
But it turns out these two vertebrates have something crucial in common: the ability to walk.
And the reason why could change the way we think about the evolution of walking in land animals—including humans.
A new genetic study from scientists at New York University reveals something surprising: Like mice, little skates possess the genetic blueprint that allows for the right-left alternation pattern of locomotion that four-legged land animals use. Those genes were passed down from a common ancestor that lived 420 million years ago, long before the first vertebrates ever crawled from sea to shore. In other words, some animals may have had the neural pathways necessary for walking even before they lived on land.
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