Naked oddball joins the Jurassic Park
Juravenator starki is simply not terrifying enough to make it on any preschooler’s list of favorite dinosaurs. For scientists, however, the new species in its bed of 150-million-year-old limestone from southern Germany will prove a sensation. The small dinosaur belongs to a subgroup of the bipedal meat-eaters called theropods, which makes Tyrannosaurus rex and Archaeopteryx, the first known bird, distant relatives of Juravenator. The fossil is almost complete and exceptionally well preserved, as reported in Nature by Dr. Ursula Göhlich at the Department for Geo- and Environmental Sciences of the Ludwig-Maximilians-Universität (LMU) in Munich and Luis M. Chiappe with the Natural History Museum of Los Angeles. Even impressions of skin and soft tissue have been found – but no signs of plumage. This makes Juravenator the exception among its otherwise feathered close relatives and could shed new light on the evolution of feathers.
There are signs that the animal was not yet fully grown. “The animal moved on two strong legs, had a very long tail and a big head,” says Göhlich. “Each of its weak arms ended in three fingers with claws.” The fossilized soft tissue belongs to the upper part of the tail. “But even though we haven’t found feathers in this area, we cannot be sure that there wasn’t any plumage at all,” says Göhlich. “But it’s very unlikely since soft tissue is only preserved under the best of conditions. Had there been feathers we would have found something.” It’s possible that plumage occurred only in specific seasons or that only adults had feathers. “There are recent species of birds where newly hatched chicks are naked,” says Göhlich. “But a condition called altriciality, when birds are being born immature and unfeathered and in need of parental care, is probably an advanced stage in evolution, as some fossils of bird embryos of the Cretaceous show signs that they were equipped to survive alone.” So in all likelihood a feathered Juravenator would have had plumage already as a hatchling. The lack of feathers in the new found fossil makes it possible that feathers developed independently a few times or were lost during evolution in certain species like Juravenator.
The name “Juravenator starki” describes the animal and location of the fossil. “Jura” stands for “Jurassic” because this is the time when the dinosaur lived and the limestone the fossil was found in had deposited. The Latin word “venator” means “hunter” and alludes to the animal’s carnivorous diet. The final “starki” pays homage to the Stark family in whose quarry the fossil has been found. Juravenator’s remains were discovered in limestone slates in southern Germany. The whole area is one of the richest sites for fossils worldwide. In the Jurassic large parts of Bavaria in the south of Germany had been covered by a shallow ocean. Limestone slowly deposited and preserved a wealth of extraordinary fossils, dragonflies with their wings, plants, invertebrates and fishes among them. Only one dinosaur, though, had been discovered before now: Compsognathus, another theropod and close Juravenator-relative. The newly discovered fossil belongs to the Jura-Museum of the small Bavarian city Eichstätt, close to the site where Juravenator starki has been found. This is also where the dinosaur will go on display shortly. (suwe)
"A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago",
Ursula B. Göhlich and Luis M. Chiappe, Nature, March 16, 2006.
Dr. Ursula Göhlich
Department for Geo- and Environmental Sciences, Section Paleontology, Ludwig-Maximilians-Universität (LMU), Munich
Dr. Göhlich can be reached at the Museum of Natural History, Vienna, Austria, at the moment.