Fossilized footprints on the Isle of Skye in Scotland have revealed that a variety of dinosaurs once stalked the island’s prehistoric landscape.
New research, published April 2 in the journal PLOS One, describes 131 footprints made by dinosaurs that traversed lagoons during the Bathonian age (168.3 million to 166.1 million years ago) of the Middle Jurassic. The location, now called Prince Charles’ Point, is named for Prince Charles Edward Stuart — known as Bonnie Prince Charlie — because he supposedly landed there following his defeat in the Battle of Culloden in 1746.
Traces left in wet sediments offer paleontologists unique insights into the lives of extinct animals, including the environments they inhabited, their size and even social habits.
The set of tracks discovered on Skye show the movements of at least two dinosaur species — one a theropod, from the group that includes predators such as Tyrannosaurus rex, the other a sauropod, from the group of long-necked plant-eaters like Brontosaurus.
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Sixty-five of the tracks were recorded as belonging to theropods and 58 to sauropods. Eight were unidentified. In the case of the theropods, even impressions of their claws were preserved. Fossilized bones from both groups of dinosaur have previously been discovered on the Isle of Skye.
The theropod footprints show distinct impressions of three toes, while the sauropod footprints are circular. They are likely to belong to relatives of the carnivorous Megalosaurus (the first dinosaur ever named) and herbivorous Cetiosaurus, respectively.
Four similar but distinct types of theropod footprint were identified. “It’s not impossible to postulate that more than one species of theropod was responsible for making a very similar type of footprint,” lead author Tone Blakesley, a paleontology graduate student at the University of Edinburgh when the discovery was made, told Live Science.
Some of the individual sets of tracks extend up to 40 feet (12 meters). They range in size from 9.8 to 23.6 inches (25 to 60 centimeters). Their patterns suggest that the dinosaurs were engaged in milling behavior — random, undirected motion.
Previous discoveries on the island have found tiny footprints, which suggests breeding locations. No such imprints were found on Prince Charles’ Point. It is unclear why the dinosaurs frequented the lagoon, which may have provided food or shelter.
The sauropod prints found there had previously been identified as fish burrows during the 1980s. Blakesley and his colleagues visited the site in 2019 and determined that they were actually dinosaur footprints after spotting a three-toed impression.
“Just as we were packing up because the tide was coming in, we found a theropod footprint,” Blakesley recounted. “This is what happens in paleontology — you pack up and leave, then you find the best thing.”
A distinctive set of conditions allowed the prints to be preserved. The researchers believe they were made in the sands of a very shallow lagoon. The light currents that passed through the water left ripples in the sand, still discernible in the sandstone in which the tracks are imprinted.
“They were walking around in a shoreline environment, a very shallow layer of water sitting on top of a very thin layer of sand,” Blakesley explained. “The sand was strong enough to retain the shape of their feet.”
When the water level rose, further sediment was deposited on top of the footprint in relatively short order — possibly by a storm. Even finer sediment was later layered on top, covering the tracks until it was eventually eroded, allowing the researchers to spot them.
“You would have to have a very quick burial of these footprints in order for them to be preserved so crisply,” Blakesley noted.
The tracks are in an intertidal zone, meaning that they are constantly subjected to the action of waves. Their timely identification is crucial to study of dinosaurs on the island because they will eventually be washed away, erasing the traces left by the massive reptiles that once inhabited the region.
