Leptoceratopsidae

Leptoceratopsids Temporal range: Late Cretaceous, 83.5–66 Ma PreЄ Є O S D C P T J K Pg N
Restoration of Leptoceratops
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Order:	†Ornithischia
Parvorder:	†Coronosauria
Family:	†Leptoceratopsidae Nopcsa, 1923
Type species
†Leptoceratops gracilis Brown, 1914
Subgroups
See text.

Leptoceratopsidae is an extinct family of neoceratopsian dinosaurs from Asia and North America. They resembled, and were closely related to, other neoceratopsians, such as the families Protoceratopsidae and Ceratopsidae, but they are more primitive and generally smaller. Definitive leptoceratopsids have so far been found exclusively in the Late Cretaceous period (late Santonian - late Maastrichtian stages) of Asia and Western North America,^[1] however material referred to leptoceratopsids from the early Campanian of North Carolina and possibly Sweden extends their geographic range into Eastern North America and potentially Europe.^[2] A possible leptoceratopsid ulna, named Serendipaceratops, has been found in Victoria, Australia. However, a 2010 study showed that it could not be confidently referred to any ornithischian family, and is considered a nomen dubium.^[3]

Leptoceratopsids range in age from Gryphoceratops, of the late Santonian, to Leptoceratops, right at the end of the Cretaceous in the late Maastrichtian. Gryphoceratops is the first definitive record of Santonian leptoceratopsid. It was named based on a partial left dentary from Alberta, Canada. Gryphoceratops represents the oldest known leptoceratopsid and probably the smallest adult-sized ceratopsian known from North America.^[1]

Leptoceratopsids are known from Eastern North America by a partial maxilla dated to the early Campanian of North Carolina, whilst the European material referred to Leptoceratopsidae consists of isolated teeth and vertebrae from the early Campanian of Sweden. The former represents the first known ceratopsian from Eastern North America, and its specialised maxillary anatomy supports the hypothesis that Appalachia was isolated from Western Europe and Laramidia for an extended period during the Late Cretaceous, resulting in an endemic Late Cretaceous fauna.^[2] The shared presence of leptoceratopsids in Appalachia and Western Europe has implications for their biogeographic dispersal, suggesting the possibility that leptoceratopsids entered Appalachia through either Western Europe or Laramidia, however it is also possible that the European leptoceratopsids also represented a distinct endemic assemblage, as the Fennoscandian Shield was also an isolated landmass during the Late Cretaceous.^[4]

Phylogeny

Leptoceratopsidae was originally named by Franz Nopcsa von Felső-Szilvás in 1923 as a subfamily Leptoceratopsinae, and its type species is Leptoceratops gracilis. Mackovicky, in 2001, defined it as a stem-based taxon and a family consisting of Leptoceratops gracilis and all species closer to Leptoceratops than to Triceratops horridus.^[5] The cladogram below follows the topologies from a 2015 analysis by Yiming He, Peter J. Makovicky, Kebai Wang, Shuqing Chen, Corwin Sullivan, Fenglu Han, Xing XuMichael J. Ryan, David C. Evans, Philip J. Currie, Caleb M. Brown and Don Brinkman.^[1]

See also

• Timeline of ceratopsian research

References

Marginocephalia
Kingdom: Animalia Phylum: Chordata Clade: Dinosauria Order: Ornithischia
Pachycephalosauria Basal Pachycephalosaurs Wannanosaurus Pachycephalosauridae Stegoceras-line Stegoceras Hanssuesia Gravitholus Colepiocephale Texacephale Pachycephalosaurus-line Homalocephale Prenocephale Goyocephale Sphaerotholus Tylocephale Acrotholus Amtocephale Pachycephalosaurini Pachycephalosaurus Dracorex Stygimoloch Alaskacephale
Ceratopsia Basal Ceratopsians Yinlong Stenopelix Micropachycephalosaurus Albalophosaurus Chaoyangsauridae Chaoyangsaurus Xuanhuaceratops Psittacosauridae Psittacosaurus Neoceratopsia Mosaiceratops Microceratus Aquilops Liaoceratops Koreaceratops Auroraceratops Archaeoceratopsidae Archaeoceratops Yamaceratops Helioceratops Coronosauria Graciliceratops Leptoceratopsidae Leptoceratops Montanoceratops Prenoceratops Udanoceratops Zhuchengceratops Gryphoceratops Unescoceratops Cerasinops Asiaceratops Bainoceratops Bagaceratopidae Ajkaceratops Gobiceratops Bagaceratops Platyceratops Protoceratopsidae Protoceratops Breviceratops Lamaceratops Magnirostris Ceratopsoidea Zuniceratops Turanoceratops Ceratopsidae
Ceratopsidae Ceratopsinae Ceratops Centrosaurinae Albertaceratops Diabloceratops Machairoceratops Monoclonius Nasutoceratopsini Avaceratops Nasutoceratops Centrosaurini Centrosaurus Coronosaurus Rubeosaurus Spinops Styracosaurus Pachyrhinosaurini Achelousaurus Einiosaurus Pachyrhinosaurus Sinoceratops Xenoceratops Wendiceratops Chasmosaurinae Agujaceratops Anchiceratops Arrhinoceratops Bravoceratops Chasmosaurus Coahuilaceratops Judiceratops Kosmoceratops Medusaceratops Mercuriceratops Mojoceratops Pentaceratops Spiclypeus Utahceratops Vagaceratops Triceratopsini Eotriceratops Ojoceratops Polyonax Regaliceratops Tatankaceratops Titanoceratops Torosaurus Triceratops
Related Categories Ornithischians Ceratopsians Pachycephalosaurs