Fossil Solves Mystery of Dinosaur Finger Evolution
• Live ScienceThe most primitive dinosaurs in the famous theropod group (that later included Tyrannosaurus rex)
had five "fingers." Later theropods had three, just like the birds that
evolved from them. But which digits? The theropod and bird digits
failed to match up if you number the digits from 1 to 5 starting with
the thumb. Theropods looked like they had digits 1, 2 and 3, while
birds have digits 2, 3 and 4.
