Millions of years ago, on what is now a windswept corner of the northern Scottish island of Skye, some of the largest animals to have walked the Earth once plodded through a shallow coastal lagoon Researchers have found the criss-cross of footprints left behind by sauropods, making the island the largest dinosaur site in Scotland.
“The new tracksite from Skye is one of the most remarkable dinosaur discoveries ever made in Scotland,” says Steve Brusatte, who led the study published in the Scottish Journal of Geology, in a statement. “There are so many tracks crossing each other that it looks like a dinosaur disco preserved in stone. By following the tracks you can walk with these dinosaurs as they waded through a lagoon 170 million years ago, when Scotland was so much warmer than today.”
Images showing the positive reliefs (a), as the rock around the prints has been eroded, and the negative reliefs (b), which just look like rock pools. Brusatte et al. 2015
The discovery was made while a team of researchers from Edinburgh University were looking for other fossil remains from the middle Jurassic period, as Skye is one of the few sites in the world where finds of this age are at the surface. As the scientists were wandering along the beach, they started to notice large, dustbin-sized potholes in the rock, filled with water and covered in seaweed.
It soon became apparent what they were looking at, as Dr. Shaena Montanari, who was not involved with study, but was part of the team when they found the footprints, explained to IFLScience: “There are some that are actually positive reliefs, and here you can see that there are four toes. If you looked even closer, some of the footprints were cut down the side, and you could see that the sediment underneath was deformed. When the dinosaur stepped on the sand, you could see the ripples in the sand underneath it, so it wasn’t just some erosional feature they’d found.”
The footprints form part of a huge trackway on the beach that extends out to sea, and is covered when the tide comes in, which could help explain why it was only just noticed recently. As luck would have it, there was another group of people at the beach who had a drone, allowing them to view the prints from the air. “When you can see it from overhead, you can really see these footprints everywhere – it’s pretty amazing,” said Dr. Montanari. The prints have been found on multiple layers of the rock formed during the middle Jurassic, which suggests that they were left by many dinosaurs over a period of generations.
Working out exactly which sauropod species was responsible, without any other fossils to go on, is a little trickier. The researchers suspect they were early, distant relatives of more well-known species such as Diplodocus, and that they probably weighed in at around 10 tonnes (11 tons) and measured at least 15 meters (50 feet) long. The tracks are also useful in shedding light on the behavior ecology of the animals, as they show that rather than being entirely land-dwelling dinosaurs (as was previously assumed), they clearly waded out into coastal lagoons.