The newly-described freshwater shark of the chalk period had teeth that resembled the emblematic Galaga video spacefighter game. Remarkably, the remains of this shark were found in the same pile of debris that contained Sue T. rex– the largest and most complete fossil of the species that have ever been discovered.
Introduction Nagandousta of Gamedadon, a newly discovered freshwater shark that swam in the southern Dakota Cretaceous rivers some 67 million years ago. It was not very large, with sizes from about 12 to 18 inches, and probably searched the riverbed in search of small fish, snails and crayfish, according to a new study published today in the magazine. The scientists they discovered Galagadon He said the shark is related to modern shark carpets, and the unusually shaped wobbegong shark is a good example.
Everything Remained From Galagadon are two dozen small teeth that are found in the same sediment that Sue, known T. rex skeleton. The remnants of this terrible tyrannosaurus were discovered 20 years ago in the Ada of South Dakota. Cleverly, the residual sediment of this work, called a matrix, was not thrown away, and was instead stored in the Field Museum in Chicago. Recently a team of scientists and volunteers decided to look at the second pile of dirt in the hope of finding some fossils, which proved to be a good idea.
As noted, only the teeth of Galagadon remain. Its other parts of the body have long vanished, especially because the cartilage does not survive very well. Paleontologist Terry Gates, the lead author of the new study and lecturer at North Carolina State University, and his colleagues, concluded on the size, form and behavior of Galagadon by comparing the teeth with those of similar species of sharks, extinct and existing.
"Fortunately, the shark teeth in our study show a close relationship with living sharks, so we have reasonable insights into their ancient lifestyle," said Eric Gorskak, a paleontologist at the Field Museum and co-author of the new study. "Teeth are generally good indicators of diet for obvious reasons. These types of reconstructions are usually more difficult with other extinct animals, such as non-bird dinosaurs, as they differ significantly from most live animal analogues. "
GalagadonTeeth are smaller than a millimeter so they can not easily be ignored.
"It was so small that you can miss it if you do not look very carefully," said Karen Norkquist, a retired chemist and volunteer who helped find the teeth in the sediment. "For the naked eye just like a small lump, you must have a microscope to see it well."
Nordquist was struck by the shape of these teeth, which reminded her of the spacecraft GalagaHer colleagues appreciated the comparison and decided to name the shark after the classic video game and Nordquist herself.
Galagadon and T. Rex, as this finds, were contemporaries. The discovery of freshwater shark in this part of the world, however, is a challenge to the conventional thinking of the South Dakota environment at that time. Sue, the idea that he lived and died near a lake formed by a fading river, but by the presence of Galagadon suggests that the region is linked to the sea, probably by a river, allowing sea sharks to move inside the country and develop the capacity to live in fresh water.
"It may seem strange today, but about 67 million years ago, what is now South Dakota has been covered with forests, swamps and curved rivers," Gates said in a statement. "Galagadon did not go down to get sick T. rex, Triceratopsor other dinosaurs that have happened in its streams. This shark had teeth that were good for catching small fish or crushing snails [crayfish]. "
The discovery is important because it will help scientists understand the diversity and potential dynamics of ancient ecosystems, especially in the context of non-bird dinosaurs such as the world-famous Sue T. rex"Gorskak said. "The sharks described in our book help the evolutionary history of modern carpet sharks, a group of sharks that currently live around Southeast Asia and Australia, but now we know we have a greater reach in their millions of years of history."
Future discoveries can shed more light Galagadon and its habitat, but so far, the discovery of an ancient shark in the same sediment that holds Sue T. rex seems unreasonably appropriate.[Journal of Paleontology]