Some 66 million years ago, a large sauropod dinosaur rested in a patch of mud along a river bank in what is now Spain, leaving behind fossil skin impressions recently found by scientists.
The impressions in the mud were later covered by sand that ultimately petrified into sandstone, forming a relief of the creature's skin as it was at the moment of its rest along the river.
Researchers from the Universitat Autònoma de Barcelona (UAB) and the Institut Catala de Paleontologia Miquel Crusafont (ICP) made the find during a geology expedition in the village of Vallcebre, close to Barcelona. The discovery is unique, they say, thanks to the age of the impressions, which date to the Late Cretaceous, just before dinosaurs went extinct.
UAB researcher Victor Fondevilla, lead author of a study on the find, said in a statement that while other fossilized skin samples of similar vintage have been found, they have only turned up in the United States and Asia. That makes the new skin impressions the vestiges of some of Europe's last dinosaurs.
"This is the only registry of dinosaur skin from this period in all of Europe," Fondevilla said, "and it corresponds to one of the most recent specimens - closer to the extinction event - in all of the world."
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The researchers think the scales are too large to have belonged to the typical carnivores or herbivorous hadrosaurs of the day. Instead, they surmise the skin belonged to a large, plant-eating sauropod - "maybe a titanosaurus," said Fondevilla - due to footprints they found from such an animal near the skin impression fossils.
All told, the team found two skin impressions - one 5 centimeters (2 inches) wide, the other 20 centimeters (8 inches) - likely made by the same dinosaur.
"The fact that they are impression fossils is evidence that the animal is from the sedimentary rock period, one of the last dinosaurs to live on the planet," said Fondevilla.
"When bones are discovered," he explained, "dating is more complicated because they could have moved from the original sediment during all these millions of years."
Looking ahead, the skin impressions "represent a valuable tool for analyzing the last occurrences of the sauropod clade before the [mass] extinction," the scientists wrote.
The researchers' findings have been published in Geological Magazine.
Photo: Universitat Autònoma de Barcelona (UAB).
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