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Ceratops
Temporal range: Late Cretaceous, 77.5 Ma
↓
Holotype left horncore
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Dinosauria
Clade: †Ornithischia
Clade: †Ceratopsia
Family: †Ceratopsidae
Subfamily: †Ceratopsinae
Marsh, 1888 sensu Abel, 1919
Genus: †Ceratops
Marsh, 1888
Species:
†C. montanus
Binomial name
†Ceratops montanus
Marsh, 1888
Synonyms
  • Proceratops montanus
    (Marsh, 1888) Lull, 1906
  • Triceratops montanus
    (Marsh, 1888) Ostrom & Wellnhofer, 1986

Ceratops (meaning 'horn face') is a dubious genus of herbivorous ceratopsian dinosaur which lived during the Late Cretaceous. Its fossils have been found in the Judith River Formation in Montana. Although poorly known, Ceratops is important in the history of dinosaurs, since it is the type genus for which both the Ceratopsia and the Ceratopsidae have been named.

History

[edit]
Illustration of the type specimen by Marsh

The first remains referred to Ceratops — an occipital condyle and a pair of horn cores — were found by John Bell Hatcher (1861–1904) in the late summer of 1888 near the Cow Creek in Blaine County in the uppermost Judith River Formation of Montana. Hatcher was at the time employed by Professor Othniel Charles Marsh who the same year named the find as the type species Ceratops montanus. The generic name was derived from Greek κέρας, keras, "horn", and ὤψ, ops, "face". The specific name referred to Montana. Marsh originally believed the animal to be similar to Stegosaurus, but with two horns on the back of its head, a body length of twenty-five to thirty feet, horizontal plates on its back and bipedal. According to Marsh it would have "represented a very strange appearance".[1] In his illustration of the horn pair, purportedly showing them from behind, Marsh had switched their position and rotated their outside to the rear to make them point inwards.[2]

The holotype, USNM 2411, was found in a layer dating from the Campanian. It consists, apart from the occipital condyle, of two supraorbital horn cores of about twenty-two centimetres length.[2] The right horn is attached to a part of the prefrontal. Marsh later referred two squamosals to the species, specimens USNM 4802 and USNM 2415. These however are more likely centrosaurine; they have also been referred to Avaceratops.[3]

In 1906 Richard Swann Lull noted that the name Ceratops had been preoccupied by a bird, Ceratops Rafinesque 1815, but also that this had been an undescribed nomen nudum, causing the name to have been still available in 1888. He nevertheless provisionally proposed a replacement name: Proceratops.[4] This is thus a junior synonym of Ceratops.

Already in the early twentieth century new finds made it increasingly difficult to distinguish the limited remains of Ceratops from several other related forms. Today, Ceratops is considered a nomen dubium.[5] However, from time to time claims are made about discoveries that, also taking into regard their provenance, might have a provable connection with the Ceratops holotype.

In 1995, David Trexler and F.G. Sweeney noted that complete material from a bonebed that had been found in Montana could enable Ceratops to be reexamined. The site, known as the Mansfield Bonebed, belongs to the same stratigraphic level as the one that yielded the original Ceratops remains. It had initially been interpreted as containing Styracosaurus, but what earlier authors considered the frill spikes of Styracosaurus turned out to be chasmosaurine orbital horns. Trexler and Sweeney pointed out that these horns closely resembled those of Ceratops, and could allow the genus to be rescued as a valid name.[6] The ceratopsids in the bonebed were later referred to the genus Albertaceratops, and later re-classified in their own genus, Medusaceratops.[7]

In 1999, Paul Penkalski and Peter Dodson concluded that Ceratops, despite being a nomen dubium because the material is too meager, appeared closely related to Avaceratops which may even be a juvenile Ceratops; there is not enough material to prove it.[8]

Later species

[edit]

In 1889 Marsh named a second species of Ceratops: Ceratops horridus.[9] This would almost immediately in a subsequent article be renamed into Triceratops horridus. Ceratops horridus is thus the type species of Triceratops. In the same article Marsh renamed Bison alticornis, his misidentification of ceratopsid material for a giant bovid, into Ceratops alticornis.[10] In 1890 Marsh renamed Hadrosaurus paucidens into Ceratops paucidens;[11] but the original assessment of Hatcher that this represented hadrosaurid material is probably correct.[2]

In 1905 Hatcher renamed three Monoclonius species into Ceratops species: Monoclonius recurvicornis Cope 1889 became Ceratops recurvicornis; Monoclonius belli Lambe 1902 was made Ceratops belli and Monoclonius canadensis Lambe 1902 was renamed Ceratops canadensis.[12] C. canadensis later was made the separate genus Eoceratops, and C. belli was made the separate genus Chasmosaurus; in 1925 William King Gregory concluded that Ceratops and Chasmosaurus were identical,[13] but this was rejected by most researchers.

In 2005, remarkably well preserved cranial and postcranial elements of a Judithian ceratopsian were discovered in Fergus County, Montana. Nicknamed "Judith", preliminary examination suggested a close affinity with C. montanus. The locality has been determined to be on or in close proximity to the stratigraphic layer of C. montanus, and not too many miles away.[14] In 2016, the new animal was named Spiclypeus, and the authors stated that it may be identical to Ceratops, which they considered a nomen dubium, or a growth stage of Albertaceratops.[15]

Species list

[edit]

The naming history can be summarised in a species list.

  • Ceratops montanus Marsh 1888: nomen dubium; type species of Ceratops Marsh 1888; = Proceratops montanus (Marsh 1888) Lull 1906
  • Ceratops horridus Marsh 1889: = Triceratops horridus (Marsh 1889) Marsh 1889
  • Ceratops alticornis (Marsh 1887) Marsh 1889: nomen dubium; = Bison alticornis Marsh 1887, = Triceratops alticornis (Marsh 1887) Lull vide Hatcher, Marsh & Lull 1907
  • Ceratops paucidens (Marsh 1889) Marsh 1890: nomen dubium; = Hadrosaurus paucidens Marsh 1889; perhaps material of Lambeosaurus lambei
  • Ceratops belli (Lambe 1902) Hatcher vide Stanton & Hatcher 1905: = Monoclonius belli Lambe 1902; = Chasmosaurus belli (Lambe 1902) Lambe 1914
  • Ceratops canadensis (Lambe 1902) Hatcher vide Stanton & Hatcher 1905: = Monoclonius canadensis Lambe 1902; = Eoceratops canadensis (Lambe 1902) Lambe 1915
  • Ceratops recurvicornis (Cope 1889) Hatcher vide Stanton & Hatcher 1905: = Monoclonius recurvicornis Cope 1889

Classification

[edit]

Ceratops was placed by Marsh in the Ceratopsidae in 1888.[1] It thus belonged to the Ceratopsia, a group of herbivorous dinosaurs with parrot-like beaks which thrived in North America and Asia during the Late Cretaceous Period, which ended roughly 66 million years ago. In 1919 the group Ceratopsinae was named by Othenio Lothar Franz Anton Louis Abel,[16] but this concept is problematic: Paul Sereno has defined it as equivalent to the Chasmosaurinae but other researchers limit it to Ceratops itself as its direct relationships are uncertain.

Diet

[edit]

Ceratops, like all ceratopsians, was a herbivore biting off plant material with its beak and processing it with its tooth batteries.

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Ceratops

View on Grokipedia
from Grokipedia
Ceratops is a dubious genus of herbivorous ceratopsid dinosaur that lived during the Late Cretaceous period (Campanian stage), approximately 76 million years ago, in what is now western North America. The genus was established by paleontologist Othniel Charles Marsh in 1888 as the type genus of the family Ceratopsidae, with the single species Ceratops montanus, based on fragmentary holotype fossils (USNM 2411) consisting of a pair of postorbital horncores and a partial occipital condyle recovered from the Judith River Formation in Fergus County, Montana. The name Ceratops derives from the Greek words keras (horn) and ops (face), reflecting the prominent horned cranial structure typical of ceratopsids. As a member of , Ceratops would have been a large, quadrupedal ornithischian characterized by a robust beak-like mouth for cropping , a bony frill extending from the back of the skull, and epiossified (bony) projections on the frill, though no frill material is preserved for this genus. The known fossils indicate straight, elongate postorbital horncores that are mediolaterally compressed and lack distinctive features, measuring about 20 cm in length and showing a roughened surface texture consistent with mature individuals. Due to the limited and non-unique morphology of these remains—which closely resemble horncores of other centrosaurine ceratopsids such as Albertaceratops and —Ceratops montanus is classified as a , meaning its generic distinctiveness cannot be confidently confirmed. Subsequent research has occasionally referred additional isolated elements, such as teeth from the and the equivalent in , , to Ceratops, but these assignments are tentative and do not resolve the genus's taxonomic ambiguity. The , a fluvial and floodplain deposit spanning about 79 to 75 million years ago, has yielded a diverse ceratopsid assemblage including well-known genera like Centrosaurus, , and Judiceratops, highlighting a period of rapid among horned dinosaurs in (the western landmass of ). Despite its uncertain status, Ceratops represents an early contribution to the understanding of ceratopsian diversity and the "Bone Wars" rivalry between and , which accelerated dinosaur discoveries in the late .

Discovery and history

Initial discovery

The genus Ceratops was first established in 1888 based on fossils collected by John Bell Hatcher during a field expedition for in the of , USA. The specimen (USNM 2411), housed at the Smithsonian Institution's , comprises a partial occipital condyle and a pair of supraorbital horn cores from Late sediments approximately 77–75 million years old. Marsh promptly described and named the type species Ceratops montanus in December of that year, recognizing it as representative of a primitive horned and establishing the family , from which the clade derives its name. This hasty naming occurred amid the , the fierce rivalry between and that spurred rapid publications of incomplete material to claim scientific priority over emerging dinosaur discoveries.

Species and nomenclature

The genus Ceratops was established by in 1888 with the naming of the C. montanus, based on the specimen USNM 2411—a fragmentary partial consisting of two supraorbital horn cores (each approximately 22 cm long) and an occipital condyle—collected from the Campanian-age Judith River Formation of . The material was discovered earlier that year by field collector John Bell Hatcher and represents the first named ceratopsid genus, though its extreme fragmentation limited diagnostic utility from the outset. In 1889, Marsh proposed a second species, Ceratops horridus, based on a more complete partial skull (YPM 1821) from the of , but he promptly reassigned it as the type species of the new genus upon recognizing additional distinguishing features, such as a third nasal horn. Marsh also named C. alticornis that year for isolated horn cores (YPM 1820) from the Denver Formation of , later synonymized with Triceratops horridus. These early designations reflected the rapid taxonomic flux during the era, where and rival competed to classify emerging ceratopsian fossils; Cope had described related fragmentary material under (e.g., M. canadensis in 1888 and M. recurvicornis in 1889), some of which was later considered for referral to Ceratops. Subsequent nomenclatural efforts included John Bell Hatcher's 1905 revision, which transferred three species to Ceratops—C. canadensis, C. recurvicornis, and C. plicocompsus—based on perceived similarities in horn morphology, though these were provisional and lacked new material. Earlier tentative links to Cope's Agathaumas (1872, based on caudal vertebrae from the Pierre Shale) and Polyonax mortuarius (1874, based on a partial skeleton including limb bones from ) were proposed but rejected due to insufficient overlap with Ceratops type material and their own fragmentary conditions. Under (ICZN) rules, Ceratops is now classified as a because the of C. montanus provides no autapomorphic features sufficient to distinguish it from other ceratopsids, rendering the genus and indeterminate. This assessment was formalized in modern reviews, including Penkalski and Dodson (1999), who emphasized the meager, non-diagnostic nature of the remains and noted potential affinities to primitive chasmosaurines like Avaceratops without confirming referral. No complete or referred specimens reliably support the genus today, confining it to historical taxonomic context.

Description

Skull morphology

The of Ceratops (USNM 2411) consists of a pair of postorbital horncores and a partial occipital condyle, providing limited insight into its cranial morphology. The horncores are approximately 20-22 cm long, subtriangular at the base, and curve outward sharply, with a roughened surface texture indicating mature individuals. Due to the fragmentary nature of the remains and the genus's status as a , detailed skull features cannot be confidently attributed to Ceratops. Tentatively referred material, such as isolated squamosals (e.g., USNM 4802), suggests a short, broad frill comparable to other Judith River ceratopsids, but these assignments remain uncertain. No frill, preorbital region, rostrum, or dental elements are preserved in the , precluding descriptions of primitive traits like fenestrae or structure.

Postcranial skeleton

No postcranial remains are known for Ceratops montanus. Due to the limited holotype material and taxonomic ambiguity, body size and posture cannot be determined with confidence. Comparisons to contemporary ceratopsids suggest it was a medium-sized quadruped, but specific estimates are unavailable.

Classification

Taxonomy

Ceratops is classified within the Linnaean hierarchy as follows: Kingdom Animalia, Phylum Chordata, Class Reptilia, Order Ornithischia, Suborder Cerapoda, Infraorder Ceratopsia, Family Ceratopsidae, Genus Ceratops. The genus serves as the eponymous basal and for the infraorder , which was formally established by in 1890 based on fragmentary material initially collected by . Marsh named the type species Ceratops montanus in 1888 from postorbital horncores and an occipital condyle recovered from the in . Due to the limited and non-diagnostic nature of the material, Ceratops montanus is regarded as a , with the postorbital horncores potentially attributable to other ceratopsids such as Spiclypeus shipporum, Albertaceratops nesmoi, or Kosmoceratops richardsoni. Despite this, the genus Ceratops is retained in taxonomic for its historical significance as the foundational of and its utility in cladistic analyses of basal ceratopsians. Marsh briefly described a second species, Ceratops paucidens, in 1890, transferring material originally assigned to the hadrosaur Hadrosaurus paucidens (1889). However, subsequent studies have reaffirmed that this material belongs to a hadrosaurid dinosaur and is not ceratopsian. By the early 20th century, workers such as refined the understanding of Ceratops montanus as a primitive member of distinct from more derived ceratopsids.

Phylogenetic relationships

Due to the extremely fragmentary nature of the holotype material—limited to a pair of postorbital horncores and a partial occipital condyle—no detailed phylogenetic analysis has included Ceratops montanus. The straight, elongate horncores resemble those of several derived ceratopsids from the of , including Albertaceratops (Centrosaurinae), , and Spiclypeus (Chasmosaurinae), suggesting an uncertain but likely position within (Neoceratopsia). Its age (~76 Ma) precludes a basal position within , as more primitive ceratopsians are known from the and of . Ceratops shares a North American distribution with other Late Cretaceous ceratopsids but lacks close relatives among earlier Asian forms, consistent with the radiation of Neoceratopsia in Laramidia following migration from Asia. Its occurrence in the Judith River Formation highlights the early diversification of ceratopsids, though its exact relationships remain unresolved due to the non-diagnostic fossils.

Paleobiology

Diet and feeding

Given its nomen dubium status and fragmentary remains, the paleobiology of Ceratops is poorly known and must be inferred from other centrosaurine ceratopsids. As a ceratopsid, Ceratops was an herbivorous dinosaur that engaged in low-level browsing, consuming vegetation such as ferns, cycads, horsetails, and angiosperms available in its Late Cretaceous (Campanian) floodplain environment. This reflects the adaptations of ceratopsids to process tougher, fibrous plant material using a complex dental battery, rather than the softer foliage exploited by basal ceratopsians. The feeding apparatus of ceratopsids included a multi-layered dental battery with leaf-shaped teeth arranged in functional rows along the , enabling precise orthal occlusion and transverse grinding through palinal motion for efficient processing of . This system, combined with a robust beak-like rostrum for cropping, supported a powerful masticatory apparatus suited to the available . Biomechanical analyses of ceratopsids indicate substantial bite forces, amplified by elongated tooth rows, tall coronoid processes, and strong adductor muscles, allowing processing of tough, fibrous —far exceeding the capabilities of basal forms. Studies suggest ceratopsids were restricted to low browsing heights of around 1 meter, despite their large body size (up to 6-9 meters in length), due to neck posture and skull orientation. As a centrosaurine ceratopsid, Ceratops likely exploited a range of low vegetation, with its inferred horns and frill potentially aiding in defense during feeding. This niche contributed to ceratopsid diversification within herbivorous communities in Laramidia.

Growth and ontogeny

Due to the limited fossils, growth and ontogeny in Ceratops are inferred from related ceratopsids, such as centrosaurines like Pachyrhinosaurus. Bone histology reveals rapid early growth driven by fibrolamellar bone tissue, enabling juveniles to reach subadult sizes quickly. Growth rates in ceratopsids supported attainment of adult body lengths of 5-7 meters by late adolescence. Evidence for in ceratopsids is limited, with some studies suggesting subtle cranial differences, but no confirmed patterns in horn or frill development from available fossils. Lifespan estimates for ceratopsids range from 20-30 years, with maturity reached around 10-15 years based on lines of arrested growth (LAGs) and growth curve analyses in taxa like . Later stages show slower growth with parallel-fibered bone and an external fundamental system (EFS), indicating determinate growth. Ontogenetic changes in ceratopsids include closure of cranial fenestrae and elaboration of horns and frills with age, as seen in and series, reflecting maturation of defensive and display structures.

Paleoecology

Habitat and distribution

Ceratops is known solely from the in north-central , , where its and limited additional material were recovered. This formation consists of nonmarine deposits laid down in a fluvial-deltaic setting, featuring meandering rivers, extensive floodplains, and associated wetlands such as swamps and lakes. The temporal range of Ceratops spans approximately 77 to 75 million years ago during the Late Campanian epoch, aligning with the Judithian North American Land Mammal Age; all known specimens derive from this interval within the formation, with no records from outside western North America. The paleoenvironment of the Judith River Formation supported a warm, humid climate conducive to lush vegetation, including dominant conifers such as Sequoia and Thuja, ferns like Osmunda, and understory elements including horsetails, alongside emerging angiosperms such as Populus and Quercus. This setting, part of a coastal plain in the Western Interior foreland basin, featured moderate to high precipitation that fostered herbivore-supporting ecosystems. Fossils of Ceratops, including cranial elements, are primarily preserved in cross-bedded channel sandstones and associated overbank deposits, indicating post-mortem transport via fluvial currents followed by rapid burial to minimize and .

Contemporaries and interactions

Ceratops inhabited the of during the stage of the , approximately 77–75 million years ago, where it coexisted with a diverse assemblage of dinosaurs. Among herbivores, it shared its environment with hadrosaurids such as Gryposaurus and , which dominated the fauna as large browsers and grazers, as well as ankylosaurids including (formerly Palaeoscincus) and , known for their armored bodies and low-slung postures. Predatory theropods were represented by tyrannosaurids like , which preyed on medium- to large-sized dinosaurs, and smaller carnivores such as , a troodontid that likely scavenged or hunted juveniles. As an early ceratopsid, Ceratops occupied a mid-sized herbivorous niche, estimated at around 5 meters in length, functioning primarily as a browser of low-lying vegetation in and riverine habitats. This role likely overlapped with that of ornithopods like Gryposaurus, potentially leading to competition for understory plants such as ferns and cycads in the forested undergrowth of Laramidia's coastal plains. Unlike more derived ceratopsids, there is no fossil evidence, such as bonebeds indicative of mass mortality in herds, suggesting Ceratops lived solitarily or in small family groups rather than large social herds. Predation pressures on Ceratops were significant, given its primitive morphology lacking prominent horns or a robust frill for defense, making it vulnerable to attacks from apex predators like . This vulnerability is inferred from bite marks and pathologies observed on bones of contemporary and related ceratopsians, including tooth-scored squamosals and healed injuries consistent with tyrannosaurid encounters, which often targeted the vulnerable flanks or necks of herbivores. Such interactions highlight Ceratops' position lower in the food web compared to heavily armored or gregarious later ceratopsids. Within the broader biodiversity of , the Western Interior landmass of , Ceratops represented a relict primitive form persisting amid a rapid radiation of more advanced neoceratopsians. The preserves at least six valid ceratopsid species, including centrosaurines like , Albertaceratops, and Lokiceratops, and chasmosaurines such as Judiceratops, , and the transitional Spiclypeus, illustrating a high diversity of horned dinosaurs evolving complex cranial ornamentation for display and defense. This assemblage underscores Ceratops' role as an early, unspecialized member of a that diversified dramatically in the , filling varied ecological roles in a dynamic, river-dominated .

References

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  4. https://www.journals.uchicago.edu/doi/full/10.1086/684289
  5. https://ucmp.berkeley.edu/history/marsh.html
  6. https://doi.org/10.1080/02724634.1999.10011182
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  9. https://pmc.ncbi.nlm.nih.gov/articles/PMC3637170/
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  12. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0126464
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  14. https://pubs.usgs.gov/bul/0257/report.pdf
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  16. https://pmc.ncbi.nlm.nih.gov/articles/PMC4871577/
  17. http://www.paleofile.com/Dinosaurs/Ornithopods/Ceratops.asp
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  19. https://pubs.geoscienceworld.org/gsa/gsabulletin/article/136/3-4/1221/627333/The-Judith-River-Belly-River-problem-revisited
  20. https://www.sciencedirect.com/science/article/pii/0031018288900855
  21. https://www.cambridge.org/core/journals/paleobiology/article/origins-of-microfossil-bonebeds-insights-from-the-upper-cretaceous-judith-river-formation-of-northcentral-montana/06F4B6D9881C06B6D98EBC94F5C43C04
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