Tetrapod Triumph! Solving Mystery Of First Land Vertebrates

Credit: Dan Piraro. Let's talk about Romer's Gap, not to be confused with the Gap of Rohan (though I would love to talk about that, too, as I am always up for a bit of Tolkien). Romer's Gap is an intriguing question mark in the fossil record that today loses a little of its mystery. On the far side of the gap, about 360 million years ago, we've got aquatic tetrapods — vertebrates with four limbs — which were at that point still pretty fishy (note: not actual scientific term). On the near side of the gap, beginning around 335 million years ago, tetrapods are already a diverse bunch of animals living quite happily on land, walking on legs and breathing air just fine, thank you very much. Romer's Gap is that period in between, when the tetrapod fossil record largely goes dark, leaving paleontologists to scratch their heads over the surf-to-turf transition. “This is a time when tetrapods really got going and started walking about, and yet we had no evidence, or very little evidence, about what was going on then,” says paleontologist Jennifer Clack, professor emeritus at Cambridge University and the lead author on an exciting new study, the first to find sedimentary hints of the tetrapods living it up on land. Published today, the research describes five new tetrapods from that mysterious gap in the record, and they matter. Because you, me, your pet dog, your pet iguana, your pet cockatoo, your fantasy pet Deinonychus that you keep asking Santa for (surely I'm not the only one...): All of us descended from tetrapods. Their fishy-to-leggy story is ours.