A fossil from a fishapod — a fish that lived just before the first four-legged land animals — suggests these creatures came in a wider variety of forms than scientists had thought. The specimen includes an elbow joint, and that joint moved in an unusually restrictive way, according to researchers.
The finding adds nuance to the story of how limbs evolved. Rather than a single, straightforward progression toward land-walking anatomy, early elbow joints appear to have taken multiple forms. The newly described fossil indicates that some fishapods evolved joint structures that limited movement in ways not seen in their better-known relatives.
Because the source reports on a single fossil, it does not offer comparisons with other specimens in detail. Still, the implication is clear: the evolutionary path to land animals was more varied than a simple linear sequence, and early limb joints may have been experimenting with different designs.