Leptoceratopsidae

Leptoceratopsids Temporal range: Late Cretaceous, 83.5–65.5Ma PreЄ Є O S D C P T J K Pg N
Skull and mandible of Zhuchengoceratops
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Order:	†Ornithischia
Clade:	†Coronosauria
Family:	†Leptoceratopsidae Nopcsa, 1923
Type species
†Leptoceratops gracilis Brown, 1914

Leptoceratopsidae is an extinct family of neoceratopsian dinosaurs from the of 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. Leptoceratopsids have so far been found exclusively in the Late Cretaceous period (late Santonian - late Maastrichtian stages) of Asia and Western North America.^[1] 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.^[2]

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]

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.^[3] The cladogram below follows the topology from a 2012 analysis by Michael J. Ryan, David C. Evans, Philip J. Currie, Caleb M. Brown and Don Brinkman.^[1]

References