User:Jgirod1/sandbox

Jgirod1/sandbox Temporal range: Late Cretaceous,
Restoration of Leptoceratops
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Dinosauria
Order:	Ornithischia
Superfamily:	Coronosauria
Family:	Leptoceratopsidae
Type species
†Leptoceratops gracilis Nopcsa, 1923
Genera
†Asiaceratops †Bainoceratops? †Cerasinops †Gryphoceratops †Ischioceratops †Leptoceratops †Montanoceratops †Prenoceratops †Udanoceratops †Unescoceratops †Zhuchengceratops

Leptoceratopsidae is an extinct herbivorous family of ceratopsid dinosaurs. Known fossils occurrences have mainly been found in North America limited to the Upper Cretaceous, though two taxa have been described from the Upper Cretaceous of Asia. The name Leptoceratopsidae stands for small horn faces; however, this family of dinosaurs never developed horned faces like their common relatives in the ceratopsid family. The family was implicitly named by Baron Francis Nopcsa in 1923 and explicitly by Peter Makovicky in 2001.

Leptoceratopsid Skull

Classification

Characteristics

Leptoceratopsids are characterized by their small size (around two meters in length), neck frills combined with a lack of horns, and pronounced jugal bones. This family is known to be facultatively bipedal. The maxilla of this family has unique anatomical characteristics. It is long, narrow, and curved downwards. They also had massive lower jaws with large rounded teeth, which separated them from ceratopsids who had shallow lower jaws and slender teeth.

Paleogeography

The dispersal of leptoceratopsids into North America is still uncertain. The basalmost leptocertopsid Asiaceratops lived between (96.2–100.5 Ma). This suggests that the ancestors of leptoceratopsids were in North America after that period. The oldest North American ancestor is Gryphoceratops which lived between (83.6–84 Ma). Because of the poor fossil record of the Late Cretaceous of vertebrates in North America, a pre-Santorian arrival in North America seems to be most likely.

Some sources claim that leptoceratopsid clades span both Asia and North America. This finding is still very tentative. What is knows for certain is that there are two Asian taxa Udanoceratops and Zhuchengceratops nested deeply within the leptoceratopsid group. This suggests a possibility of dispersal from North America into Asia. Within the broader context of the North American Late Cretaceous dinosaur biogeography, the temporal and geographic distribution of other North American leptoceratopsids suggests at least intermittent connections between North America and Asia, likely followed by an interval of isolation and then reconnection. These periods of isolations and connections help define the different evolutionary patterns of leptoceratopsids from the Westernmost side of North America (Laramidia) and the Easternmost side of North America (Appalachia). Laramidia was connected with Asia while Appalachia remained isolated. With this in mind, many of the Laramidians resemble Asian dinosaurs more closely than Appalachian dinosaurs after the split of North America.

Phylogenetics

Leptoceratopsidae was originally named by Baron Franicis Nopsca in 1923 as a subfamily Leptoceratopsinae, and its type species is Leptoceratops gracilis. In 2001, Mackovicky, defined it as a stem-based taxon and a family consisting of Leptoceratops gracilis and all species closer to Leptoceratops than to Triceratops horridus. The cladogram below follows the topologies from a 2015 analysis by Peter J. Makovicky, Et. Al.

Leptoceratops gracilis skeleton

Ceratopsia

Yinlong Chaoyangsaurus Xuanhuaceratops Psittacosauridae Neoceratopsia Liaoceratops Aquilops Yamaceratops Auroraceratops Archaeoceratopsidae Helioceratops Archaeoceratops oshimai Archaeoceratops yujingzensis Koreaceratops Coronosauria Leptoceratopsidae Asiaceratops Cerasinops Montanoceratops Ischioceratops Prenoceratops Leptoceratops Udanoceratops Zhuchengceratops Gryphoceratops Unescoceratops Graciliceratops Protoceratopsidae Bagaceratops Lamaceratops Breviceratops Magnirostris Protoceratops hellenikorhinus Protoceratops andrewsi Ajkaceratops Zuniceratops Ceratopsidae