Hesperonychus
Graphical reconstruction of Hesperonychus
- North America
Hesperonychus is a genus theropod dinosaur from the Upper Cretaceous (late Campanian ) of North America. This Dromaeosauride is currently the smallest known carnivorous dinosaur from North America.
Fund history
The approximately 75 million years old fossil remains of Hesperonychus were found in 1982 in the Dinosaur Park Formation in Dinosaur Provincial Park, Alberta, Canada. Began in 2007, the University of Calgary to investigate the findings and published in 2009 Nicholas Long Rich and Philip J. Currie, the first description of the new genus with the only kind ( type species ) Hesperonychus elizabethae.
Features
The first description of the genus and species was based on a pelvic girdle ( holotype UALVP 48778 ). Since the pelvic bone pubic bone ( pubis ) and ilium ( ilium ) were already fully grown together, it is, notwithstanding the small size of the bones of an adult individual. The weight of the animal is estimated to be about 1.9 kg. This Hesperonychus is the smallest found so far in North America non-avian theropod -. When his prey insects as well as small mammals and amphibians are suspected.
System
Hesperonychus is because of some similarities in the pelvic anatomy - found in the group of Microraptorinae to which the four-winged Microraptor and the feathered dinosaurs Sinornithosaurus belong, both from - including a lateral outgrowth of the pubis, a far back lying arc of the pubic shaft and a spoon-shaped pubic base the much older Lower Cretaceous Jehol group are known in China.
A phylogenetic analysis revealed no close relationship with the other North American dromaeosaurs. Instead Hesperonychus the first Microraptorinae found in North America and the youngest by far a member of this clade; he lived about 45 million years later than its East Asian relatives. Studies of fossil collections of Dinosaur Park and Oldman Formation ( formerly the " Judith River Formation " together ) large number of finds of single bones of small, basal Dromaeosauriden to light that have been assigned by Long Rich and Currie provisionally Hesperonychus. These findings indicate that this small dinosaur made up a significant part in the carnivore community of Upper Cretaceous biota.
Documents
- Long Rich, N.R. & Currie, P. J. ( 2009). "A microraptorine ( Dinosauria Dromaeosauridae ) from the Late Cretaceous of North America". In: Proceedings of the National Academy of Sciences. Abstract.