Caption: This is a photograph of a museum reconstruction of Acanthostega, an early tetrapod. Acanthostega measured about 2 feet (0.6m) in length. – Credit: Jennifer Clack
Cartoon depictions of the first animals to emerge from the ocean and walk on land often show a simple fish with feet, venturing from water to land. But according to Jennifer Clack, a paleontologist at the University of Cambridge who has studied the fossils of these extinct creatures for more than two decades, the earliest land vertebrates — also known as tetrapods — were more diverse than we could possibly imagine.
“Some looked like crocodiles, some looked like little lizards, some like moray eels, and some were snake-like,” said Clack. “They occupied all sorts of niches and habitats. And they varied tremendously in size — from about 10 cm long to 5 meters.”
Long before mammals, birds, and even dinosaurs roamed the Earth, the first four-legged creatures made their first steps onto land, and quickly inhabited a wide range of terrestrial environments. These early land vertebrates varied considerably in size and shape, said Clack.
To understand the anatomical changes that accompanied this diversity, Clack teamed up with two biologists who work on living fishes — Charles Kimmel of the University of Oregon, and Brian Sidlauskas of the National Evolutionary Synthesis Center in North Carolina.
The researchers focused on 35 early tetrapods that lived between 385 and 275 million years ago.
That’s a great model. I’d love to take a trip back in time and see these things … as long as I didn’t accidentally step on one and destroy the human race.