Fossils of what could possibly be the earliest four-legged vertebrates to walk on land were recently found in Scotland, according to a new report in the journal Nature Ecology & Evolution.

The team behind the discovery said the lizard-like animals that left behind these fossils lived approximately 355 million years ago when the precursors of modern reptiles, birds, and mammals appeared out of swamps.

Discovery Fills a Huge Fossil Record Gap

The discovery fills in a 15 million-year gap in the fossil record and included five completely intact fossils, with many more pieces of bones yet to be categorized.

The researchers said some fossil fragments look like lizards or newts, and some are bigger, with crocodile-like dimensions.

“We’re lifting the lid on a key part of the evolutionary story of life on land,” team member Jennifer Clack, of the University of Cambridge, told BBC News. “What happened then affects everything that happens subsequently – so it affects the fact that we are here and which other animals live with us today.”

About 360 years ago, several kinds of life, including early on fish, were wiped out a global extinction event. For roughly the next 15 million years, a major time in the progression of four-legged vertebrates, there is a hole in the fossil record.

To put it another way– we know very little around how fish-like animals developed the limbs that could help them on land.

Nick Fraser, of National Museums Scotland, said modern-day Scotland just might have been where the first land animals emerged from the water.

“If you want to draw the analogy to Neil Armstrong’s first step on the Moon,” he said, “it was one small step for man but a giant leap for mankind, well, this in some ways is a small step out of the water for these animals but it’s a giant leap forward for the future evolution of life on land.”

Just a few locations on the planet have produced similar fossils from this time period. One site is in Scotland, west of Glasgow, where only a single fossil has been discovered. Fossils bits have also been discovered in the US and Canada.

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Image credit: Mark Witton/National Museums Scotland

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