''Ischioceratops'' () is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of small herbivorous

ceratopsian Ceratopsia or Ceratopia ( or ; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

that lived approximately 69

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

during the latter part of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

Period in what is now

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

. ''Ischioceratops'' was a small sized, moderately-built, ground-dwelling, quadrupedal

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

, whose total body length has been estimated to be about . The ceratopsians were a group of dinosaurs with parrot-like beaks which fed on vegetation and thrived in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

and

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

during the Cretaceous Period, which ended approximately 66 million years ago, at which point they all became extinct. Its name means "ischium horned face", referring to the peculiar shape of the ischiatic bones. ''Ischioceratops'' existed in the Wangshi Group during the late Cretaceous. It lived alongside centrosaurines, saurolophines, and tyrannosaurines. The most common creatures in the formation were '' Sinoceratops'' and '' Zhuchengtyrannus''.

Discovery and naming

In 2015, the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

''Ischioceratops zhuchengensis'' was named and described by He Yiming, Peter J. Makovicky, Wang Kebai, Chen Shuqing, Corwin Sullivan, Han Fenglu and Xu Xing. The generic name combines a reference to the ''os ischii'', its uniquely formed

ischium The ischium () form ...

, with ~ceratops, "horn face", a usual suffix in the names of Ceratopia. The suffix itself is derived from Greek ''keras'', "horn", and ''ops'', "face". The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

refers to the provenance from Zhucheng. Because the name was published in an

electronic publication Electronic publishing (also referred to as publishing, digital publishing, or online publishing) includes the digital publication of e-books, digital magazines, and the development of digital libraries and catalogues. It also includes the editing ...

, PLoS ONE, '' Life Science Identifiers'' were required for its validity. These were 19A423ED-8EAA -4842-9ECF-695876EC5EC0 for the genus and 71CD0FAE-070C-4CC4-96CC-B37D5B1071CE for the species. ''Ischioceratops'' was one of eighteen dinosaur taxa from 2015 to be described in open access or free-to-read journals. Holotype of Ischioceratops

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

ZCDM V0O016 was discovered in Kugou, a locality in the

Shandong Shandong ( , ; ; alternately romanized as Shantung) is a coastal province of the People's Republic of China and is part of the East China region. Shandong has played a major role in Chinese history since the beginning of Chinese civilizati ...

Province of China which presents layers of the

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

Wangshi Group, possibly dating from the late Campanian or earliest

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

. It is part of the Zhucheng Dinosaur Museum collection and it represents an incomplete, partially articulated specimen comprising the entire

sacrum The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part ...

, a few ossified tendons, both halves of the

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

, the anteriormost fifteen caudal

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

in an articulated series, and the right

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

and

fibula The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity is ...

Description

Size and distinguising traits

''Ischioceratops'' was a relatively small ceratopsian, reaching in length. The describing authors indicated some distinguishing traits. The taxon has been referred to Leptoceratopsidae and is distinguished from other known leptoceratopsids based on the following combination of characters: nine sacral vertebrae, more than in any other known basal (non-ceratopsid) ceratopsian but fewer than in ceratopsids; the ischium has a robust shaft that resembles that of a recurved bow and flares gradually to form a subrectangular-shaped obturator process in its middle portion while an elliptical fenestra perforates the obturator process. This morphology, unique for the Dinosauria as a whole, was seen as a single

autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

, unique derived character.

Skeleton

''Ischioceratops'' is one of the few ceratopsian dinosaurs which is not known by the skull. The most peculiar traits are located in the ischium. With most relatives the ischium shaft has a constant curvature to the rear. Another characteristic of ''Ischioceratops'' is the presence of an elevation in the proximal part of its tail, which is present also in ''

Protoceratops ''Protoceratops'' (; ) is a genus of small protoceratopsid dinosaurs that lived in Asia during the Late Cretaceous, around 75 to 71 million years ago. The genus ''Protoceratops'' includes two species: ''P. andrewsi'' and the larger ''P. hellenik ...

'', '' Koreaceratops'' and in a more similar way in '' Montanoceratops'' and '' Cerasinops''. The elevation forms a tail crest.

Classification

Phylogenetic analyzes confirmed ''Ischioceratops'' as a leptoceratopsid. Its closest relative taxon or sister species was '' Montanoceratops''. The following cladogram is based on an analysis in the describing paper of 2015.

References