THE giant lizard steps slowly through the mists of water vapour amid searing heat as it stalks its prey.
At more than twice the size of a man and with ‘hands’ equipped with lethal talons instead of feet, the terrifying reptile has little to fear from the plant-eating cousin that is about to become its latest meal.
This is no ‘lizard man’ from a Hollywood B-movie, but an animal that walked the shores of Arran some 270 million years ago.
The discovery of dozens of the beast’s footprints have caused huge excitement in the tightly-knit world of paleontology because it is the first time they have been found in Scotland and the prints are the largest found anywhere in the world.
The bizarre 12ft-long creature is known as chirotherium, meaning ‘hand beast’, because its ‘feet’ are actually more like hands.
The discovery means the creature was roaming the ancient land that became Arran long before the island’s highest mountain, Goatfell, even started to form, and before the arrival of dinosaurs.
Peder Aspen, 61, former curator of the Museum of Geology at Edinburgh University, discovered the first footprint while taking a group of students to study salt crystals near Blackwaterfoot.
"I turned a boulder over and lo and behold there was a footprint. This one was big enough that I could put my hand into it. The claw marks were quite visible," he said.
"You look at the footprints on the shore and think, ‘My goodness, not so very long ago - relatively speaking - there were reptiles walking towards the water, and here we are millions of years later doing the same thing’."
Since then, 50 sets of footprints have been discovered at four different locations on Arran, which was on the same latitude as the Sahara at the time the animals were alive.
The lizard is thought to have been similar to a crocodile - one of its descendants, which also include the dinosaurs - except with a shorter snout and long legs that extended straight down from its body, rather than sticking out to the side.
The Arran footprints are the biggest ever found in the world at up to 16 inches, compared with previous discoveries of chirotherium footprints of 12 inches in Arizona, Argentina and parts of Europe.
Aspen, who lives in Fife, said the footprints provided some clue as to what kind of animal made them.
"We haven’t found any bones at all. It’s a bit like Robinson Crusoe finding Man Friday’s footprints.
But you can make deductions about what they were like.
"The interesting thing about chirotherium is the thumbs appeared to be on the outside. It’s most odd, as if you have turned your hands over. They used to think chirotherium crossed its legs when it walked, no wonder it became extinct! But in fact it was a pinkie and it was an adaptation for walking on soft ground."
Aspen and Dr Neil Clark, curator of palaeontology at Glasgow University’s Hunterian Museum, have written a scientific paper on the footprints along with Hammy Corrance, an amateur enthusiast from Irvine.
"These are the first ones ever to have been found in Scotland," Clark said.
"From having nothing to having four different localities and close on 50 footprints in the space of a year is quite amazing. For Scotland it’s quite a significant discovery."
At the time of the chirotherium, Arran was part of a giant area containing most of the world’s land surface, Pangaea. It was on the eastern shore of a desert but there is some evidence of vegetation suggesting there was occasional rain.
"There’s a lot of evidence of a wet habitat so it’s very near the shore. There’s also a lot of evidence of salt crystals so there was high evaporation. It was very hot," Clark said.
"Arran itself would have been a low flat plain. Goatfell wouldn’t have been there."
While the creatures’ size could be estimated by the stride patterns, little was known about the animals’ actual behaviour.
"There is a fossil that was found in Switzerland that had a very similar hand structure to the footprints," Clark added.
The Swiss reptile was a carnivore, although the chirotherium’s diet is still a source of debate, with some believing it was a herbivore, as prey animals have not been found in the same areas as the reptiles.
Chirotherium expert Dr Geoffrey Tresise, former keeper of geology at the National Museums and Galleries on Merseyside, and a supporter of the carnivore theory, said the Arran footprints may have been made after a heavy downpour.
"There may just have been a storm which created a temporary lake that was drawing a lot of animals to the one area at that particular time," he said.
"There may have been quite a lot of vegetation, which probably attracted herbivorous reptiles which would have attracted chirotherium."
Fiona Gorman, an amateur archaeologist at Arran Heritage Museum in Brodick, which is staging an exhibition about the chirotherium, subsequently found a natural cast of a chirotherium footprint made over millions of years after the impression was filled with sand which turned to stone.
"It’s very strange indeed, very like a human hand," she said.
"And to think it’s been lying in the sea for millions of years."
SCOTLAND’s ancient rocks have yielded much to excite those interested in life before the first humans walked the earth.
Among the most important finds was a fossil of a 330-million-year-old reptile nicknamed ‘Lizzie the Lizard’ in a quarry near Bathgate in 1988.
Remains of strange mammal-like reptiles - a kind of lizard dog or pig that lived 260 million years ago - found near Lossiemouth and several discoveries on Skye, including the fossilised bone of a giant long-necked plant-eating dinosaur, have also made headlines.
Radical 19th century Scottish journalist Hugh Miller is widely credited for helping to popularise palaeontology. Working as a stonemason in his native Cromarty, the young Miller discovered the fossils of fish from the Devonian period, sparking a lifelong fascination. He also unearthed the fossils of Jurassic sea reptiles and ancient crocodiles on the Isle of Eigg.