Ancient reptile footprints subvert theories about when animals evolved into land

Australian scientists have identified the oldest fossil footprints of reptile-like, dating back 350 million years.

This discovery suggests that after the first animals emerged from the ocean about 400 million years ago, they developed the ability to live on land much faster than previously assumed.

"We think the transition from fin to limb took longer," said Stuart Sumida, a paleontologist at California State University.

The earliest known reptile footprints previously discovered in Canada date back to 318 million years ago.

Ancient footprints from Australia were found on a piece of sandstone recovered near Melbourne and show reptile-like feet, long toes and hook claws.

Scientists estimate that the animal is about 2 1/2 feet (80 cm) in length, possibly similar to modern monitor lizards. The findings were published in Nature on Wednesday.

Hook claws are a key identification clue, said study co-author and paleontologist at Uppsala University in Sweden.

"This is a walking animal," he said.

A piece of sandstone found near Melbourne, Australia, preserves fossil footprints from reptile-like animals about 350 million years ago. The footprints are highlighted in yellow (forefoot) and blue (backfoot) and show three animals-like movements, the researchers said. Professor Grzegorz niedzwiedzki / Per per erik Ahlberg via AP

Only the animals that evolved only survive on the paws that have developed throughout history. The earliest vertebrates - fish and amphibians - have never developed hard nails and are still dependent on the watery environment to lay eggs and reproduce.

However, branches of the evolutionary tree have led to modern reptiles, birds and mammals (called amniotic fluid), whose feet are developed with nails or paws, suitable for walking on hard feet.

"This is the earliest evidence we've ever seen to prove animals with claws," Sumida said.

While ancient reptiles were inhabited, the area was hot and steaming, and vast forests began to cover the earth. Australia is part of Gondwana's supercontinent.

Alberg said the Fossil Fossil Trails recorded a series of events in the day. A reptile stabbed the ground before the heavy rain fell. Some raindrops have partially covered their tracks. Then two more reptiles ran in the opposite direction, and the ground became hard and covered with sediment.

Fossils “The orbits are beautiful because they tell you what life is like, not just some look,” said John Long, a paleontologist at Flinders University in Australia.