Scientists have discovered a new species of four-limbed animal that lived around 336million years ago at what is now East Kirkton Quarry, but which was then part of a landmass close to the Equator.
Measuring around half a metre long, with a scaly belly and a tail, the tetrapod also had a large fourth toe on its hind foot, allowing it a great stride and the ability to move at speed.
The animal, which is close to the group from which reptiles evolvedm, has been named Termonerpeton makrydactylus or “boundary crawler with the long toe” and is now the eight tetrapod found at East Kirkton.
Dr Timothy Smithson, of the Department of Zoology at the University of Cambridge, described the limestone quarry as an “extraordinary” place where exceptional preservation of the tetrapods had allowed greater study of animals and plants of the period.
He said: "It’s important to say that the diversity of all the tetrapods from East Kirkton from the period is the most diverse of anywhere in the UK. It really is an extraordinary site."
The long-toed creature was discovered back in late 1980s by fossil hunter Stan Wood, with the specimen kept at Cambridge University, where studies have only recently established its significance.
Dr Smithson said the animal lived during the the Carboniferous period, when what is now Edinburgh sat close to the equator.
At what is now the quarry, he described a small lake “surrounded by volcanos” and lots of vegetation.
Dr Smithson added: “This lake, however, is not sustaining living things. It seems as if very little was able to live in it, either because of the chemistry or because it was too hot. We know from equivalents, such as the hot geyzers at Yellowstone National Park, that these pools can be very warm. Not boiling – but over 50 degrees. East Kirkton could have been as hot as time.
Scorpions, harvest spiders and millipedes are also known to have made their home there , as well as a “very diverse” array of plant life,
Dr Smithson said: “All the fossils we have got from the East Kirkton limestone are from animals and plants that lived on the land so they probably fell into the pool and couldn’t get out.”
Dr Smithson said the creature may have fallen into the water by walking over plants which covered the surface of the lake.
“The lake may have been covered in these mats of algae, so it possibly fell in and couldn’t get out. If the water was very hot, it could have cooked. If there was something chemically unsuitable in the water, it would effectively been poisoned, or it may have drowned.”
All of the eight East Kirkton quarry tetrapods have differing characteristics, with the long toe perhaps giving the Termonerpeton makrydactylus an advantage over the other animals roaming the area, given it likely allowed it to cross multiple terrains, including those covered in volcanic ash.
-The study was first published in the Communications Biology journal.