Browsing by Author "Napoli, James G."
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Item A new dromaeosaurid (Dinosauria: Coelurosauria) from Khulsan, Central Mongolia (American Museum novitates, no. 3982)(American Museum of Natural History., 2021-11-08) Napoli, James G.; Ruebenstahl, Alexander; Bhullar, Bhart-Anjan S.; Turner, Alan H. (Alan Hamilton); Norell, MarkDromaeosaurid theropods represent a rare but important clade of nonavialan dinosaurs. Their close evolutionary relationship to modern birds has placed them at the center of paleontological research for the last several decades. Herein we describe a new species of dromaeosaurid—Kuru kulla, gen. et sp. nov.—based on a partial skeleton from the Late Cretaceous Khulsan locality (Barun Goyot Formation) of Mongolia. This species is diagnosed by several autapomorphies within Dromaeosauridae, including a sharp groove anterior and ventral to the narial fossa on the premaxilla, a posterolaterally directed hornlet on the posterodorsal process of the lacrimal, a deep surangular bearing two surangular foramina, and anteriorly displaced pleurocoels on the dorsal centra. The taxon is further characterized by a unique combination of characters, including a mediolaterally narrow metatarsal II, serrations on both carinae of the dentary teeth, hyposphenes that are widely separated but joined by a web of bone, and a lacrimal with a poorly developed boss on its lateral surface. Phylogenetic analysis finds Kuru kulla to be the sister taxon of Adasaurus mongoliensis, from the slightly later Nemegt Formation, with which it is united by three synapomorphies: a posterior surangular foramen that is ~30% the depth of the surangular, absence of a fourth trochanter of the femur, and thoracic centra that are markedly longer than their midpoint widths. The recognition of this taxon has important implications for common assumptions of Mesozoic terrestrial ecosystem structure and adds new data to a recently recognized pattern in dromaeosaurid faunal composition among Late Cretaceous localities in Mongolia and Inner Mongolia (Nei Mongol Autonomous Region, China).Item Psittacosaurus amitabha, a new species of ceratopsian dinosaur from the Ondai Sayr locality, central Mongolia. (American Museum novitates, no. 3932)(American Museum of Natural History., 2019-07-25) Napoli, James G.; Hunt, Tyler.; Erickson, Gregory M.; Norell, Mark.Psittacosaurus is the most speciose nonavian dinosaur genus, represented by at least 10 (and possibly as many as 19) species uncovered over a wide geographic range. Here, we report a new species of large-bodied Psittacosaurus from the Ondai Sayr locality in central Mongolia, which has hitherto produced only one other Psittacosaurus specimen. This new species is characterized by: (1) an elongate snout, with a gently inclined rostronasal margin, (2) a cranium dorsally convex rather than flat, (3) a subtemporal length less than 40% of total skull length, (4) a maxillary lamina that cups the posterior toothrow, (5) five premaxillary foramina arrayed in an arc, (6) an antorbital fossa as long as it is wide, and (7) a palpebral with a well-developed posterior tonguelike process. Psittacosaurus amitabha is resolved as the most basal member of the genus Psittacosaurus in our phylogenetic analysis. This taxon expands our knowledge of the already-speciose genus Psittacosaurus as well as our understanding of the Ondai Sayr fauna, which is poorly known in comparison to other Mongolian Early Cretaceous localities.Item Supplemental Material for 'Psittacosaurus amitabha, a new species of ceratopsian dinosaur from the Ondai Sayr locality, central Mongolia. (American Museum novitates, no. 3932)'(2019-07-25) Napoli, James G.; Hunt, Tyler; Erickson, Gregory M.; Norell, Mark A.Supplemental Material for 'Psittacosaurus amitabha, a new species of ceratopsian dinosaur from the Ondai Sayr locality, central Mongolia. (American Museum novitates, no. 3932)'