Главная » 2013 » Октябрь » 12 » FEATHER-LIKE STRUCTURES AND SCALES IN A JURASSIC NEORNITHISCHIAN DINOSAUR FROM SIBERIA
3:08 PM
FEATHER-LIKE STRUCTURES AND SCALES IN A JURASSIC NEORNITHISCHIAN DINOSAUR FROM SIBERIA
GODEFROIT, Pascal, Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium; SINITSA, Sofia, Institute of Natural Resources, Ecology and Cryology, SB RAS, Chita, Russia; DHOUAILLY, Danielle, Université Joseph Fournier, La Tronche, France; BOLOTSKY, Yuri, Institute of Geology and Nature Management, FEB RAS, Blagoveschensk, Russia; SIZOV, Alexander, Institute of the Earth’s Crust, SB RAS, Irkutsk, Russia Recent discoveries in Middle–Late Jurassic and Early Cretaceous deposits from northeastern China have revealed that numerous theropod dinosaurs were covered by feathers. Furthermore, filamentous integumentary structures were also recently described in rare Early Cretaceous ornithischian dinosaurs from Liaoning Province in China. Whether these filaments can be regarded as epidermal and therefore part of the evolutionary lineage towards feathers remains controversial. Here we describe a new basal neornithischian dinosaur, based on isolated bones and partial skeletons collected in two monospecific bonebeds from the Middle–Late Jurassic Kulinda locality in the Transbaikal region (Russia). Varied integumentary structures were found directly associated with skeletal elements, supporting the hypothesis that simple filamentous feathers, as well as compound feather-like structures comparable to those in theropods, were widespread amongst the whole dinosaur clade. Moreover, scales along the distal tibia and on the foot closely resemble the secondarily-appearing pedal scales in extant birds. More surprisingly, dorso-ventral movements of the tail were prevented by large imbricated scales on its dorsal surface. It is hypothesized that, at the same time early feathers evolved within the whole dinosaur clade, genetic mechanisms limiting the growth of long epidermal structures on the distal portion of the hind limb and on the tail were selected as they facilitate bipedal terrestrial locomotion. http://dinoweb.ucoz.ru/forum/29-1790-1
DINOWEB - палеозойские и мезозойские тетраподы