The humble rodent “thumb” may not seem like an obvious window into evolution, but its keratinized tip – the unguis (hoof, claw, or nail) – turns out to reveal striking insights into rodent history and ...

The legions of squirrels breaking into backyard bird feeders benefit from a surprising trait developed over millions of years—tiny hands with four claws and a human-looking thumbnail. This combination ...

The arrangement of the bones that form the joint (the articulation) between the lower jaw and the skull is a key hallmark of vertebrates. Their configuration has long been used to draw a line in the ...