Falcarius
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 Reconstruction from NatureIllustration by Mike Skrepnick, University of Utah
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| Falcarius utahensis Kirkland et al., 2005 |
Falcarius was a therizinosaurian dinosaur genus found in east-central Utah, in the United States, in 2005. Its name is derived from the word sickle ('falcarius' in Latin being a sickle cutter), which scientists have used to describe its unwieldy clawed hands. This find, along with the recently discovered therizinosauroid Beipiaosaurus from the Early Cretaceous of China, may clarify the group's relationship with the larger family of theropod dinosaurs.
The discovery site, in a 2 acre (8,000 square meter) area of Utah's Cedar Mountain Formation, includes the remains of hundreds, perhaps thousands, of specimens of the new species. Only a small number of the available fossils have been excavated. From examining fossilized bones from several individual animals, scientists describe the dinosaurs as feathered, rotund, sickle-clawed creatures. Falcarius utahensis averaged 3.7 to 4 m (12 to 13 ft) in length and just over 1.2 m (4 ft) tall. With its long neck, it could apparently reach about 1.5 m (5 ft) off the ground to munch leaves or fruit. Its leaf-shaped teeth and 10 to 13 cm (4 to 5 inch) claws indicate that it consumed both meat, quite probably small animals such as lizards, and plant material.
Falcarius utahensis lived approximately 125-130 million years ago, in the early Cretaceous Period, and closely resembles dinosaurs belonging to the family Therizinosauridae, part of the group Maniraptora. Falcarius itself probably does not belong to this former group, although it does belong to the more inclusive group Therizinosauria. The group is characterized by bird-like wide hips, a comparatively large brain case and long necks with hollow bones typical of plant eaters. The less-primitive Asian specimens were covered in shaggy feathers; this is assumed for Falcarius as well. A larger member of the group, a sloth-like therizinosaur called Nothronychus, was described in 2001, based on discoveries made in the late 1990s in New Mexico. It, however, was estimated to be only 90 million years old.
While a scientific description of Falcarius was published in 2004, it was not formally named until a subsequent paper was published in the May 2005 issue of the journal Nature. Co-authors of the study include Scott Sampson, chief curator at the University of Utah's Utah Museum of Natural History, and Lindsay Zanno, a doctoral student at the University. Dr. Sampson is quoted as saying that this species "...is the missing link between predatory dinosaurs and the bizarre plant-eating therizinosaurs".
A skeletal mount of Falcarius utahensis went on display at the Utah Museum of Natural History on 29 June 2005.
[edit] References
- Kirkland, Zanno, DeBlieux, Smith and Sampson, (2004). "A new, basal-most therizinosauroid (Theropoda: Maniraptora) from Utah demonstrates a Pan-Laurasian distribution for Early Cretaceous therizinosauroids." Journal of Vertebrate Paleontology, 24(3) 78A.
- Kirkland, J. I., Zanno, L. E., Sampson, S. D., Clark, J. M. & DeBlieux, D. D. (2005). "A primitive therizinosauroid dinosaur from the Early Cretaceous of Utah." Nature, 435: 84-87.
- Smith, Kirkland, Sanders, Zanno and DeBlieux, (2004). "A comparison of North American therizinosaur (Theropoda: Dinosauria) braincases." Journal of Vertebrate Paleontology, 24(3).
