'Martharaptor,' a New Dinosaur, Discovered in Utah
The Cedar Mountain Formation of eastern Utah is a torn, windswept arrangement of rock. To the peckish observer, it might resemble a delectable layer cake, oozing with different colored varieties of chocolate and maybe even some coffee grounds. But this is one stale piece of cake. Its filling, which is really sediment, was deposited during the latter half of the early Cretaceous Period, approximately 98 to 127 million years ago. This makes the Cedar Mountain Formation less appealing to food lovers and more so to paleontologists. Since the 1990s, the site has yielded a profuse variety of dinosaur fossils.
It's at this location where scientists recently discovered a new theropod dinosaur, Martharaptor greenriverensis. Scientists Phil Senter of Fayetteville State University in North Carolina and James Kirkland and Donald DeBlieux of the Utah Geological Survey just described their findings in a study published in the online open-access journal PLoS ONE.
Scientists excavated the specimen specifically from the Hayden-Corbett Quarry, which is at the top of approximately 20 centimeters of thick sandstone. The specimen's genus name -- Martharaptor -- honors Martha Hayden, the co-discoverer of the site. The species name -- greenriverensis -- refers to the nearby city of Green River, Utah, which is about eight miles southeast of the discovery location. (Below image: A collection of vertebrae, scapula, forelimb bones, and pelvic bones. Scale bar = 50 mm)
The Martharaptor skeleton was found in many separate pieces over an area of less than two square meters. There was no duplication of bone elements, leading the researchers to believe that there was only one individual present. Phylogenetic analysis weakly placed M. greenriverensis into the taxon Therizinosauroidea. Dinosaurs of this group varied widely in size, from 7.3 feet in length up to 40 feet, were mostly herbivorous or omnivorous, and were primarily bipedal.
The skeletal material discovered was rather sparse, so the authors did not go into specifics about Martharaptor's height, size, and other potentially distinguishing features. The available bones did, however, provide the researchers with enough evidence to clearly differentiate Martharaptor from its therizinosauroid counterparts. Perhaps with further excavations and fossil discoveries, a clearer picture will eventually become available.
For now, the finding suggests that the Cedar Mountain Formation still teems with unknown fossils waiting to be unearthed. Not bad for a piece of layer cake.
Source: Senter P, Kirkland JI, DeBlieux DD (2012) Martharaptor greenriverensis, a New Theropod Dinosaur from the Lower Cretaceous of Utah. PLoS ONE 7(8): e43911. doi:10.1371/journal.pone.0043911