Hefty Dinosaurs Trampled Denmark

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.