The Solway Firth is the scene of the historic find

A small colony of tadpole shrimps has been identified in a pool at the Wildfowl and Wetlands Trust nature reserve at Caerlaverock near Dumfries.

The crustaceans, which were found in a pool on the reserve, were thought to have been extinct in Scotland.

They were last seen north of the border over 50 years ago.

The last Scottish colony, further along the Solway from Caerlaverock, was thought to have been lost through sea encroachment just after the Second World War.

Older than dinosaurs

The only known UK population has been in the New Forest in England until the new discovery, which was made by a researcher, Larry Griffin, looking for natterjack toads.

Mr Griffin told BBC Radio's Good Morning Scotland programme: "When I dipped my net in I pulled out some of these beasties which I hadn't seen before.

"They look like a small form of the little horseshoe crabs, so I knew I was onto something different, but I didn't know at that time that they were this living fossil."

It is not yet known where the creatures came from or how long they have been at Caerlaverock.

They were thought to have been extinct in Scotland since the middle of the last century, so it's a major discovery Brian Morell Wildfowl and Wetlands Trust

But experts say it is possible that eggs have been dormant in the mud for decades, waiting for the right conditions to come to life.

Fossilised remains prove tadpole shrimps were around 220 million years ago in the Triassic period - pre-dating the dinosaurs.

Experts say they do not appear to have changed in appearance since that time.

Brian Morell, of the Wildfowl and Wetlands Trust at Caerlaverock, said: "They were thought to have been extinct in Scotland since the middle of the last century, so it's a major discovery.

"We'll have to do some DNA analysis just to see if they are linked to that population."