Huge Trove of Dinosaur Footprints Discovered in Scotland
New fossil trackways show that giant Jurassic dinosaurs roamed ancient lagoons.
Illustration by Jon Hoad
Hundreds of tracks discovered along Scotland’s coast show that huge, long-necked dinosaurs once trod there.
The footprints form the largest dinosaur site ever found in Scotland.
They also show that sauropods, which included the largest dinosaurs of
all time, were at home along the shore.
The giant dinosaurs' relationship to water has long been debated. For
much of the 20th century, paleontologists thought sauropods had to
wallow in swamps, where the water could support their massive bulk. But
finds during the “Dinosaur Renaissance” of the 1970s and '80s banished
this old imagery. Sauropods turned out to be surprisingly light for
their size, more likely to float than to sink their feet to a lake
bottom. A new view had sauropods roaming forests, rather than steaming
marshes.
Now, the new footprints on the Isle of Skye are part of a growing
picture that some sauropod dinosaurs also frequented the edges of
lagoons and ancient coasts. The geology of the Isle of Skye site
presented unequivocal evidence that the dinosaurs were walking around a
brackish lagoon.
A Giant Find
“We had gone out to a lonely stretch of coast on the far northeastern
tip of the island,” says University of Edinburgh paleontologist Stephen
Brusatte, who scouted the Isle of Skye site after a geologist spotted
bones there. After spending the day finding mostly shark teeth and other
small fossils, Brusatte says, he and fossil fish expert Tom Challands
spotted what looked like a pothole. It was a dinosaur's footprint.
That initial find turned into a string of tracks over an area measuring about 49 feet (15 meters) by 82 feet (25 meters).
But it’s not just the size of the tracksite that’s remarkable. The
Isle of Skye footprints date back to the Middle Jurassic, over 161
million years ago. This, Brusatte says, “is one of the most poorly
understood time intervals in dinosaur evolution.” The tracks offer a new
glimpse into which dinosaurs lived in the area and how they behaved
during this mysterious time.
Hundreds of dinosaur tracks cover a newly discovered site on Scotland's Isle of Skye.
Photograph by Stephen Brusatte
Photograph by Stephen Brusatte
Dinosaur bones are rare in Middle Jurassic rocks, notes Emory
University paleontologist Anthony Martin, and even fossil skeletons can
be transported from where the animal died. Tracks, however, are a
different story. Footprints “are extremely valuable for filling gaps in
our understanding of dinosaur evolution,” Martin says.
The exact identity of the dinosaurs that left the footprints is
unknown. Unless a dinosaur literally dies in its tracks, it’s usually
impossible to match a skeletal foot to footprint.
But the tracks preserve enough detail for Brusatte and coauthors to identify them as sauropod dinosaurs—like the embattled Brontosaurus
and its relatives—that walked with their legs relatively close to each
other along the midline. A good candidate for this sort of trackmaker,
Brusatte says, is a Middle Jurassic dinosaur named Cetiosaurus, which also happens to be one of the first dinosaurs ever named.
Creatures of the Lagoon
The ancient environment where these dinosaurs tromped around also came as a surprise.
Paleontologists are as yet uncertain as to why sauropods at the ancient Isle of Skye and other sites around the world regularly skirted the margins of seas, lagoons, and wetlands. Perhaps the lagoons and coasts boasted a food source, protection from predators, or some other draw, Brusatte says.
Paleontologists are as yet uncertain as to why sauropods at the ancient Isle of Skye and other sites around the world regularly skirted the margins of seas, lagoons, and wetlands. Perhaps the lagoons and coasts boasted a food source, protection from predators, or some other draw, Brusatte says.
Photograph by Stephen Brusatte
Martin agrees, noting that finding sauropod tracks in coastal
habitats is not all that surprising given that these places “provided
paths of least resistance for sauropods moving from one place to
another” thanks to flat, easy-to-navigate shorelines where predatory
dinosaurs would have had more difficulty ambushing prey given the lack
of cover.
So while sauropods were largely landlubbers, some of them were
comfortable with at least getting their feet a little wet. “Dinosaurs
were probably capable of doing a lot more, and living a whole lot more
places,” Brusatte says, “than we give them credit for.”
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