科学家给两种新角龙命名-凯发k8官网

two new horned ² have been named based on fossils collected from alberta, canada. the new species, unescopceratops koppelhusae and gryphoceratops morrisoni, are from the leptoceratopsidae family of horned dinosaurs. the herbivores（食草动物） lived during the late cretaceous period between 75 to 83 million years ago. the ⁴ are described in research published in the jan. 24, 2012, online issue of the journal cretaceous research. "these dinosaurs fill important gaps in the ⁵ history of small-bodied horned dinosaurs that lack the large horns and frills of relatives like triceratops from north america," said michael ryan, ph.d., curator of vertebrate paleontology at the cleveland museum of natural history, lead author on the research. "although horned dinosaurs originated in asia, our analysis suggests that leptoceratopsids radiated to north america and ⁶（多样化） here, since the new species, gryphoceratops, is the earliest record of the group on this continent."

unescoceratops koppelhusae lived approximately 75 million years ago. it measured about one to two meters (6.5 feet) in length and weighed less than 91 kilograms (200 pounds). it had a short frill extending from behind its head but did not have ornamentation（装饰物） on its ⁷. it had a parrot-like ⁸. its teeth were lower and rounder than those of any other leptoceratopsid. in addition, its hatchet-shaped ⁹ had a distinct portion of bone that projected below the jaw like a small chin.

the lower left jaw fragment of unescoceratops was discovered in 1995 in ^{1 10} park, a united nations educational, scientific and cultural organization (unesco) world heritage site by philip currie, ph.d., now of the university of alberta. originally described in 1998 by ryan and currie, the dinosaur was referred to as leptoceratops. subsequent research by ryan and david evans, ph.d., of the royal ontario museum in toronto, canada, ¹¹ the ³ was a new genus and species. the genus is named to honor the unesco world heritage site designation for the locality where the specimen was found and from the greek "ceratops（角龙） ," which means "horned face." the species is named for eva koppelhus, ph.d., a palynologist at the university of alberta and wife of currie.

gryphoceratops morrisoni lived about 83 million years ago. it had a shorter and deeper jaw shape than any other leptoceratopsid. researchers believe the individual was a full-grown adult. based on unique characteristics of the jaw and its size, the researchers believe that gryphoceratops was an adult that did not exceed one-half meter in length. this means it is the smallest adult-sized horned dinosaur in north america and one of the smallest adult-sized plant-eating dinosaurs known.

lower right jaw fragments of gryphoceratops were discovered in southern alberta in 1950 by levi sternberg while he worked for the royal ontario museum. the genus is named for "gryphon," a ¹² greek figure with the body of a lion and the head of an eagle, which is a reference to the animal's ¹³（有喙的） face. the species name honors ian morrison, a royal ontario museum technician, who discovered how the bones fit together.

second author evans, associate curator of vertebrate palaeontology at the royal ontario museum and assistant professor at the university of toronto, said, "small-bodied dinosaurs are typically poorly represented in the fossil record, which is why fragmentary ¹⁴ like these new leptoceratopsids can make a big contribution to our understanding of dinosaur ecology and evolution."

contributing authors are philip currie, ph.d., of the university of alberta; caleb brown of the university of toronto; and don brinkman, ph.d., of the royal tyrrell museum of palaeontology.