Life reconstruction of the early tetrapod Pederpes showing the forelimb bones beneath the skin. Credit: Image copyright 2021, Julia Molnar.
Phys.org has a piece about some new research that explored how early tetrapods used they newly acquired legs. It's generally accepted that tetrapods migrated from water to land about 390 million years ago, during the Devonian Period. And, while the stages in the transition are understood, this research was about function.... How did the animals move on land and how was it different than modern animals. The research is detailed in a paper that appeared in the journal Science Advances.
When tetrapods (four-limbed vertebrates) began to move from water to land roughly 390 million years ago it set in motion the rise of lizards, birds, mammals, and all land animals that exist today, including humans and some aquatic vertebrates such as whales and dolphins.
The earliest tetrapods originated from their fish ancestors in the Devonian period and are more than twice as old as the oldest dinosaur fossils. They resembled a cross between a giant salamander and a crocodile and were about 1-2 meters long, had gills, webbed feet and tail fins, and were still heavily tied to water. Their short arms and legs had up to eight digits on each hand and foot and they were probably ambush predators, lurking in shallow water waiting for prey to come near.
Scientists know how the fins of fish transformed into the limbs of tetrapods, but controversies remain about where and how the earliest tetrapods used their limbs. And, while many hypotheses have been proposed, very few studies have rigorously tested them using the fossil record.
