Aug. 19, 2008 -- Prehistoric footprints over 1-foot wide and 8-inches deep suggest that enormous sauropod dinosaurs once trampled Denmark, according to a new study that describes the first known Danish Mesozoic dinosaur tracks, which date to 144 million years ago.
The study, which has been accepted for publication in the journal Palaeogeography, Palaeoclimatology, Palaeoecology, also documents the first lungfish burrows for that location and era, as well as possible tracks for small carnivorous dinosaurs.
All were found on the Danish island of Bornholm to the east of mainland Denmark.
"There is evidence of several different types of dinosaurs inhabiting Bornholm during the Mesozoic," lead author Finn Surlyk told Discovery News.
Surlyk, a professor at the University of Copenhagen's Geological Institute, explained that teeth for at least two types of dromaeosaurs, which were bird-like carnivores, as well as sauropod teeth were previously found at the site. Remains for ancient turtles, a huge ancient fish called Lepidotes and a streamlined shark known as Hybodus, meaning "humped tooth," have also been unearthed.
"So everything indicates (the dinosaurs) were living there as part of a diverse ecosystem," Surlyk said.
Like a child who leaves a handprint in wet clay or cement, the dinosaurs made their mark on Denmark by trampling through organic-rich, dark brown mud. Based on finds in the substrate, it appears they marched over plant roots, pieces of wood and pyrite, also known as "fools gold" because it resembles the more precious metal.
"They walked in a very shallow water lake or swamp," Surlyk said. "I think they were feeding there and simply lived in the surrounding dry land."
The lungfish burrows suggest that the climate on the island was much warmer than it is today. This eel-looking fish digs into moist lake floors when the water level of its habitat drops.
The burrows, extremely rare for this time period, further suggest a seasonal climate with alternating wet and dry periods, which would have been perfect for supporting vegetation and dinosaurs, like sauropods, which chomped on the plants.
Since Bornholm was a horst, or a raised fault block, it's likely that the dinos and other animals lived in a mini paradise at the time that would have been isolated from mainland Europe.
The newly identified Danish island of dinosaurs is a rarity for Nordic countries. Such animal remains have not been found in Finland and Iceland, and for good reason. Iceland, Surlyk explained, "did not exist at the time, since the Atlantic Ocean was not yet formed."
Mainland Norway only lays claim to a single, yet intriguing, miniscule piece of prosauropod bone. Prosauropods, like sauropods, were plant eaters, except they possessed a very large thumb claw for defense. They could grow to over 29 feet in length and weigh up to four tons.
Norway's Arctic archipelago of Svalbard, on the other hand, has yielded a few dinosaur footprints as well as fossils for several Mesozoic marine reptiles.
Niels Bonde from the Geological Institute at the University of Copenhagen did not work on the latest study, but he led the excavation that found one of the Bornholm dromaeosaur teeth. That was a government-sponsored project meant to assist unemployed individuals, and a group of these people discovered, and dug out, the big dino tooth.
Bonde explained that the tooth must have belonged to a carnivorous dinosaur that lived around 130 million years ago and measured over 13 feet long.
Given that the newly identified sauropod tracks appear to be crossed in places by footprints of such a carnivorous dinosaur, there is little doubt that, despite the lush setting, this part of prehistoric Denmark was a dinosaur-eat-dinosaur place millions of years ago.
Related Links:
Discovery News blog: Born Animal
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