Misplaced Pages

#766233

48-586: Protoceratopsidae is a family of basal (primitive) ceratopsians from the Late Cretaceous period. Although ceratopsians have been found all over the world, protoceratopsids are only definitively known from Cretaceous strata in Asia , with most specimens found in China and Mongolia . As ceratopsians, protoceratopsids were herbivorous, with constantly replacing tooth batteries made for slicing through plants and

96-418: A metaspecies with highly variable phylogenetic positions. In 2003, Vladimir Alifanov named, but did not define, a new ceratopsian family Bagaceratopidae to include Bagaceratops , Platyceratops , Lamaceratops and Breviceratops . In 2019 Czepiński analyzed a vast majority of referred specimens to the ceratopsians Bagaceratops and Breviceratops , and concluded that most were in fact specimens of

144-528: A classification, though sources have differed on what its rank should be. Most who still employ the use of ranks have retained its traditional ranking of suborder, though some have reduced to the level of infraorder. In clade -based phylogenetic taxonomy , Ceratopsia is officially defined in the PhyloCode as "the largest clade containing Ceratops montanus and Triceratops horridus , but not Pachycephalosaurus wyomingensis . Under this definition,

192-512: A deep and wide oral cavity, though more narrow than in predecessors like Psittacosaurus , which may have aided in breathing or thermoregulation. In Protoceratopsidae, the nasal cavity, which was ancestrally one large cavity, was split into two by the hard palate. This splitting likely happened to accommodate the deeper oral cavity. The vertebral column of protoceratopsids was S-shaped, and the vertebrae had unusually long neural spines , with spines on caudal vertebrae that were five times as tall as

240-429: A dinosaur, but noted that even though the fossil lacked a skull, it was different from any type of dinosaur then known. He named the new species Agathaumas sylvestris , meaning "marvellous forest-dweller". Soon after, Cope named two more dinosaurs that would eventually come to be recognized as ceratopsids: Polyonax and Monoclonius . Monoclonius was notable for the number of disassociated remains found, including

288-589: A forward-oriented pubis . Marsh considered the group distinct enough to warrant its own suborder within Ornithischia. The name is derived from the Greek κέρας / kéras meaning 'horn' and ὄψῐς / ópsis meaning 'appearance, view' and by extension 'face'. As early as the 1960s, it was noted that the name Ceratopsia is actually incorrect linguistically and that it should be Ceratopia . However, this spelling, while technically correct, has been used only rarely in

336-433: A fossil horn. The frill bone was interpreted as a part of the breastbone. In 1888 and 1889, Othniel Charles Marsh described the first well preserved horned dinosaurs, Ceratops and Triceratops . In 1890 Marsh classified them together in the family Ceratopsidae and the order Ceratopsia. This prompted Cope to reexamine his own specimens and to realize that Triceratops , Monoclonius , and Agathaumas all represented

384-414: A hooked beak for grabbing them. Protoceratopsids were small ceratopsians around 1-2.5 m in length. Their bony frill and horns were much smaller than more derived members of Ceratopsia, such as ceratopsids . Protoceratopsids were relatively small ceratopsians, averaging around 1-2.5 m in length from head to tail. Protoceratopsids have a frill and rostral bone characteristic of all ceratopsians. Their snout

432-400: A medium-sized sclerotic ring indicates that the animal is a predator, a large sclerotic ring indicates that it is nocturnal, and the largest ring size indicates it is a nocturnal predator. Eye size is an important adaptation in predators and nocturnal animals because a larger eye has increased sensitivity and resolution. Because of the energy necessary to maintain a larger eye and the weakness of

480-666: A mostly North American group of mostly small bodied and quadrupedal ceratopsians. Another subset of neoceratopsians is called Coronosauria , which is "the smallest clade containing Protoceratops andrewsi and Triceratops horridus ". Coronosaurs show the first development of the neck frill and the fusion of the first several neck vertebrae to support the increasingly heavy head. Within Coronosauria, two groups are generally recognized. One group can be called Protoceratopsidae and includes Protoceratops and its closest relatives, all Asian. The other group, Ceratopsoidea , includes

528-403: A narrow strap-shaped paroccipital process, a very small occipital condyle , and an upturned dorsal margin of the predentary. In Protoceratops and Bagaceratops (and also in the non-protoceratopsid Leptoceratops ), there is a blade-shaped parietal sagittal crest . The relationships of Graciliceratops to other protoceratopsids remain unclear due to its fragmentary nature, and it is regarded as

SECTION 10

#1732786790767

576-421: A single group of similar dinosaurs, which he named Agathaumidae in 1891. Cope redescribed Monoclonius as a horned dinosaur, with a large nasal horn and two smaller horns over the eyes, and a large frill . Ceratopsia was coined by Othniel Charles Marsh in 1890 to include dinosaurs possessing certain characteristic features, including horns, a rostral bone , teeth with two roots , fused neck vertebrae , and

624-401: A walk or a trot. Their legs may have been straight, creating an upright posture, but there are some theories that they were splayed out to the side, contributing to their slowness. The skeleton of Protoceratops juveniles indicates that protoceratopsids were able to employ facultative bipedalism when young and became obligate quadrupeds in adulthood. However, adults still had proportions allowing

672-403: Is particularly wedge-shaped with tall and narrow nostrils situated high on it. The antorbital fenestra is unusually small, and the antorbital fossa sits high on the skull with a slit connecting it to a sinus in the maxilla. This sinus is unique to Protoceratopsidae. Protoceratopsids may have had cheeks to hold food in their mouths. They have very well-defined maxillary and dentary ridges where

720-525: Is the basal-most protoceratopsid and Bagaceratops the derived-most one. Below are the proposed phylogenetic relationships within Protoceratopsidae by Czepiński: Protoceratops andrewsi [REDACTED] Protoceratops hellenikorhinus [REDACTED] Breviceratops [REDACTED] Bagaceratops [REDACTED] Based on the size of its sclerotic ring , Protoceratops had an unusually large eye among protoceratopsids. In birds,

768-635: Is traditional for ceratopsian genus names to end in " -ceratops ", although this is not always the case. One of the first named genera was Ceratops itself, which lent its name to the group, although it is considered a nomen dubium today as its fossil remains have no distinguishing characteristics that are not also found in other ceratopsians. Early members of the ceratopsian group, such as Psittacosaurus , were small bipedal animals. Later members, including ceratopsids like Centrosaurus and Triceratops , became very large quadrupeds and developed elaborate facial horns and frills extending over

816-599: The Cretaceous Period , although ancestral forms lived earlier, in the Jurassic . The earliest known ceratopsian, Yinlong downsi , lived between 161.2 and 155.7 million years ago. The last ceratopsian species, Triceratops prorsus , became extinct during the Cretaceous–Paleogene extinction event , 66 million years ago . Triceratops is by far the best-known ceratopsian to the general public. It

864-482: The centrum . The neural spines on the caudal vertebrae were longer in the middle of the tail than at the base, increasing the tail's height and flattening it. The middle of the tail was rigid and straight. The entire tail was quite horizontally flexible, but vertical movement was limited. The neck had limited mobility, especially in the lateral direction. The neck allowed individuals to bend their necks up and down so that they could reach food. The family Protoceratopsidae

912-608: The epoccipital bones . The name is a misnomer, as they are not associated with the occipital bone . Epoccipitals begin as separate bones that fuse during the animal's growth to either the squamosal or parietal bones that make up the base of the frill. These bones were ornamental instead of functional, and may have helped differentiate species . Epoccipitals probably were present in all known ceratopsids. They appear to have been broadly different between short-frilled ceratopsids ( centrosaurines ) and long-frilled ceratopsids ( chasmosaurines ), being elliptical with constricted bases in

960-480: The human lineage belongs to the "Black Skull", Paranthropus aethiopicus field number KNM WT 17000 , the earliest known robust hominid ancestor and the oldest robust australopithecine discovered to date. The prominence of the crest appears to have been an adaptation for the P. aethiopicus' heavy chewing, and the Black Skull's cheek teeth are correspondingly large. Smaller sagittal crests are also present on

1008-399: The skull . On the tip of a ceratopsian upper jaw is the rostral bone, an edentulous (toothless) ossification, unique to ceratopsians. Othniel Charles Marsh recognized and named this bone, which acts as a mirror image of the predentary bone on the lower jaw. This ossification evolved to morphologically aid the chewing of plant matter. Along with the predentary bone, which forms the tip of

SECTION 20

#1732786790767

1056-413: The analysis of Eric M. Morschhauser and colleagues in 2019 , along with all previously published diagnostic species excluding the incomplete juvenile Archaeoceratops yujingziensis and the problematic genera Bainoceratops , Lamaceratops , Platyceratops and Gobiceratops that are very closely related to and potentially synonymous with Bagaceratops . While there were many unresolved areas of

1104-403: The capacity to occasionally stand on two legs. Tereschenko proposed that protoceratopsids were actually aquatic, using their laterally-flattened tails as a paddle to aid in swimming. According to Tereschenko, Bagaceratops was fully aquatic while Protoceratops was only partially aquatic. Protoceratopsids likely lived in highly arid regions. Specimens are often found in sandstones . Because

1152-462: The day and survive in an arid environment without highly developed cooling mechanisms. There is no conclusive evidence supporting sexual dimorphism for Protoceratops andrewsi However, the frill may have been used in mating displays. The frill may have been brightly colored and used in head-bobbing displays similar to those of modern-day iguanas and chameleons to attract a mate. Leonardo Maiorino and his team used geometric morphometrics to analyze

1200-496: The dimorphism in Protoceratops andrewsi and concluded that there is no difference in male and female structures. Alternatively, Dodson's analysis of structure sizes in large Protoceratops found that they were dimorphic. The length and width of the frill, parietal fenestra, and external nares, the nasal height, the skull width, the orbit height, and the coronoid process height all varied with sex. There are three phases in

1248-481: The family Ceratopsidae and closely related animals like Zuniceratops . This clade is defined as "the largest clade containing Ceratops montanus and Triceratops horridus , but not Protoceratops andrewsi ". Ceratopsidae itself includes Triceratops and all the large North American ceratopsians and is further divided into the subfamilies Centrosaurinae and Chasmosaurinae . All previously published neoceratopsian phylogenetic analyses were incorporated into

1296-533: The first evidence of ceratopsid horns and frills. Several Monoclonius fossils were found by Cope, assisted by Charles Hazelius Sternberg , in summer 1876 near the Judith River in Chouteau County , Montana. Since the ceratopsians had not been recognised yet as a distinctive group, Cope was uncertain about much of the fossil material, not recognizing the nasal horn core, nor the brow horns, as part of

1344-404: The former group, and triangular with wide bases in the latter group. Within these broad definitions, different species would have somewhat different shapes and numbers. In centrosaurines especially, like Centrosaurus , Pachyrhinosaurus , and Styracosaurus , these bones become long and spike- or hook-like. A well-known example is the coarse sawtooth fringe of broad triangular epoccipitals on

1392-631: The former. Although the genera Gobiceratops , Lamaceratops , Magnirostris , and Platyceratops , were long considered valid and distinct taxa, and sometimes placed within Protoceratopsidae, Czepiński found the diagnostic features used to distinguish these taxa to be largely present in Bagaceratops and thus becoming synonyms of this genus. Under this reasoning, Protoceratopsidae consists of Bagaceratops , Breviceratops , and Protoceratops . Based on cranial characters such as presence or absence of premaxillary teeth and an antorbital fenestra, P. andrewsi

1440-508: The frill becomes even larger, the epijugal is fully formed, and a small nasal horn develops. There is evidence that Protoceratops formed groups. Specimens of juveniles and young adults are often found in groups, although adults tend to be solitary. The nature of these groups is not completely known, though herds of young likely formed for protection from predators, and adults are believed to have come together for communal nesting. Protoceratopsids were likely slow runners and tended to move at

1488-615: The frill of Triceratops . When regarding the ossification's morphogenetic traits, it can be described as dermal. The term epoccipital was coined by paleontologist Othniel Charles Marsh in 1889. The first ceratopsian remains known to science were discovered during the U.S. Geological and Geographical Survey of the Territories led by the American geologist F.V. Hayden . Teeth discovered during an 1855 expedition to Montana were first assigned to hadrosaurids and included within

Protoceratopsidae - Misplaced Pages Continue

1536-404: The genus Trachodon . It was not until the early 20th century that some of these were recognized as ceratopsian teeth. During another of Hayden's expeditions in 1872, Fielding Bradford Meek found several giant bones protruding from a hillside in southwestern Wyoming . He alerted paleontologist Edward Drinker Cope , who led a dig to recover the partial skeleton. Cope recognized the remains as

1584-884: The later ceratopsians had upright forelimbs and the larger species may have been as fast as rhinos , which can run at up to 56 km or 35 miles per hour. Sagittal crest A sagittal crest tends to be present on the skulls of adult animals that rely on powerful biting and clenching of their teeth, usually as a part of their hunting strategy. Skulls of some dinosaur species, including tyrannosaurs , possessed well developed sagittal crests. Among mammals, dogs, cats, lions, and many other carnivores have sagittal crests, as do some leaf eaters, including tapirs and some apes . Sagittal crests are found in robust great apes , and some early hominins ( Paranthropus ). Prominent sagittal crests are found among male gorillas and orangutans , but only rarely occur in male chimpanzees such as Bili apes . The largest sagittal crest ever discovered in

1632-460: The life cycle of a protoceratopsid: juvenile, subadult, and adult. Juveniles are roughly one third the size of an adult and have an underdeveloped frill and nasal bump. They have not developed epijugals. Nests containing juveniles have been found indicating that they received some level of parental care. In the subadult stage, individuals are two thirds the size of an adult, and the frill and quadrates grow wider. The epijugal begins forming. As an adult,

1680-462: The lower jaw in all ornithischians , the rostral forms a superficially parrot -like beak. Also, the jugal bones below the eye are prominent, flaring out sideways to make the skull appear somewhat triangular when viewed from above. This triangular appearance is accentuated in later ceratopsians by the rearwards extension of the parietal and squamosal bones of the skull roof, to form the neck frill. The neck frills of ceratopsids are surrounded by

1728-484: The members of Chaoyangosauridae and Psittacosaurus are excluded from Neoceratopsia, while all more derived ceratopsians are part of this clade. A slightly less inclusive group is Euceratopsia , named and defined by Daniel Madzia and colleagues in 2021 as "the smallest clade containing Leptoceratops gracilis , Protoceratops andrewsi , and Triceratops horridus ". This clade includes the family Leptoceratopsidae and all more derived ceratopsians. Leptoceratopsids are

1776-664: The most basal known ceratopsians are the family Chaoyangsauridae and the well known genus Psittacosaurus , from the Early Cretaceous Period, all of which were discovered in northern China or Mongolia . The rostral bone and flared jugals are already present in all of these forms, indicating that even earlier ceratopsians remain to be discovered. The clade Neoceratopsia is defined as "the largest clade containing "the largest clade containing Triceratops horridus , but not Chaoyangsaurus youngi and Psittacosaurus mongoliensis ". By this definition, only

1824-547: The most commonly preserved elements of ceratopsian skeletons and many species are known only from skulls. There is a great deal of variation between and even within ceratopsian species. Complete growth series from embryo to adult are known for Psittacosaurus and Protoceratops , allowing the study of ontogenetic variation in these species. Most restorations of ceratopsians show them with erect hindlimbs but semi-sprawling forelimbs, which suggest that they were not fast movers. But Paul and Christiansen (2000) argued that at least

1872-449: The muscles in the cheek would have connected, and a number of foramina dotted the maxilla which allowed branches from the trigimenal nerve to reach the tissues attached to the maxilla, indicating that such tissues were likely muscular. The end of the upper jaw was likely not fleshy but instead covered by a horn-like material, and the upper and lower jaws curved in towards each other. Compared to more derived ceratopsians, protoceratopsids had

1920-439: The neck. While these frills might have served to protect the vulnerable neck from predators , they may also have been used for display , thermoregulation , the attachment of large neck and chewing muscles or some combination of the above. Ceratopsians ranged in size from 1 meter (3.3 feet) and 23 kilograms (51 pounds) to over 9 meters (30 feet) and 9,100 kg (20,100 lb). Ceratopsians are easily recognized by features of

1968-488: The posture of some animals is preserved, it is likely that they were buried during a sandstorm or a dune collapse. Protoceratopsids have so far been found in rocks from the Late Cretaceous , dating to between about 75 and 71 million years ago. Ceratopsians originated in Asia and had two major dispersal events. The first was the migration of Leptoceratopsidae 's ancestor through Europe and into North America. The second dispersal

Protoceratopsidae - Misplaced Pages Continue

2016-480: The scientific literature, and the vast majority of paleontologists continue to use Ceratopsia. As the ICZN does not govern taxa above the level of superfamily , this is unlikely to change. Following Marsh, Ceratopsia has usually been classified as a suborder within the order Ornithischia. While ranked taxonomy has largely fallen out of favor among dinosaur paleontologists, some researchers have continued to employ such

2064-415: The skull that corresponds with a larger orbit, Nick Longrich argues that this structure may have been an adaptation for a nocturnal lifestyle. Protoceratops ' s mouth structures and general abundance indicate it was not a predator, so if it were also diurnal , then it would have been expected to have a much smaller sclerotic ring size. If Protoceratops was nocturnal, it could avoid the hottest parts of

2112-413: The skulls of other Paranthropines, including Paranthropus boisei and Paranthropus robustus . The shrinking of the sagittal crest in human ancestors was widely attributed to a growing brain and shrinking teeth. However, it was discovered in 2004 by a group of researchers led by Dr. Hansell Stedman, that a frameshift mutation shrank the individual muscle fibers of the temporalis muscle, which attached to

2160-686: The stem-based clade including "all coronosaurs closer to Protoceratops than to Triceratops ". Sereno's definition ensures that Protoceratopsidae is monophyletic , but probably excludes some dinosaurs that have been traditionally thought of as protoceratopsids (for example, Leptoceratops and Montanoceratops ). The latter genera are now often classified in a mostly North American family Leptoceratopsidae . Sereno in 2000 included three genera in Protoceratopsidae: Protoceratops , Bagaceratops , and Graciliceratops . Derived characters shared by these dinosaurs include

2208-1824: The strict consensus, including all of Leptoceratopsidae, a single most parsimonious tree was found that was most consistent with the relative ages of the taxa included, which is shown below. Psittacosaurus sinensis [REDACTED] Psittacosaurus mongoliensis [REDACTED] Yinlong downsi [REDACTED] Chaoyangsaurus youngi [REDACTED] Hualianceratops wucaiwanensis [REDACTED] Xuanhuaceratops niei Stenopelix valdensis [REDACTED] Liaoceratops yanzigouensis [REDACTED] Archaeoceratops oshimai [REDACTED] Aquilops americanus [REDACTED] Auroraceratops rugosus [REDACTED] Graciliceratops mongoliensis [REDACTED] Asiaceratops salsopaludalis Mosaiceratops azumai [REDACTED] Yamaceratops dorngobiensis [REDACTED] Helioceratops brachygnathus [REDACTED] Leptoceratops gracilis [REDACTED] Ischioceratops zhuchengensis [REDACTED] Prenoceratops pieganensis [REDACTED] Udanoceratops tchizhovi [REDACTED] Zhuchengceratops inexpectus [REDACTED] Koreaceratops hwaseongensis [REDACTED] Montanoceratops cerorhynchus [REDACTED] Cerasinops hodgskissi [REDACTED] Gryphoceratops morrisoni Unescoceratops kopelhusae Bagaceratops rozhdestvenskyi [REDACTED] Magnirostris dodsoni Protoceratops hellenikorhinus [REDACTED] Protoceratops andrewsi [REDACTED] Ajkaceratops kozmai [REDACTED] Zuniceratops christopheri [REDACTED] Turanoceratops tardabilis [REDACTED] Diabloceratops eatoni [REDACTED] Ceratopsidae [REDACTED] Unlike almost all other dinosaur groups, skulls are

2256-555: Was 15 million years later, this time of Ceratopsidae's ancestors across the Bering Land Bridge into North America between 120Ma and 140Ma. Protoceratopsids are found in Asia but not North America. Ceratopsia Ceratopsia or Ceratopia ( / ˌ s ɛr ə ˈ t ɒ p s i ə / or / ˌ s ɛr ə ˈ t oʊ p i ə / ; Greek : "horned faces") is a group of herbivorous , beaked dinosaurs that thrived in what are now North America , Europe , and Asia , during

2304-560: Was introduced by Walter W. Granger and William King Gregory in May 1923 as a monotypic family for Protoceratops andrewsi . Granger and Gregory recognized Protoceratops ' s close relationship to other ceratopsians, but considered it primitive enough to warrant its own family, and perhaps suborder. Protoceratopsidae was later expanded to include all ceratopsians that were too advanced to be psittacosaurids, but too primitive to be ceratopsids. In 1998, Paul Sereno defined Protoceratopsidae as

#766233