The Ceratopsia,

Hatcher, J. B.; Lull, Richard Swann; Marsh, O. C.; Osborn, Henry Fairfield

doi:10.5962/bhl.title.60500

Cited by 67 publications

(110 citation statements)

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“…A portion of the supraoccipital remains between the exoccipitals and contributes to the posterior foramen magnum at least through subadult ontogeny as observed in the skull of MOR 1120. In the adult Triceratops skull, UCMP 113697, the supraoccipital is completely excluded from the foramen magnum and overlies the exoccipitals, as described by Hatcher et al (1907) and confirmed by Forster (1996b) and Dodson et al (2004) as the adult condition.…”

Section: Resultsmentioning

confidence: 98%

Major cranial changes during Triceratops ontogeny

2006

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This is the first cranial ontogenetic assessment of Triceratops, the well-known Late Cretaceous dinosaur distinguished by three horns and a massive parietal-squamosal frill. Our analysis is based on a growth series of 10 skulls, ranging from a 38 cm long baby skull to about 2 m long adult skulls. Four growth stages correspond to a suite of ontogenetic characters expressed in the postorbital horns, frill, nasal, epinasal horn and epoccipitals. Postorbital horns are straight stubs in early ontogeny, curve posteriorly in juveniles, straighten in subadults and recurve anteriorly in adults. The posterior margin of the baby frill is deeply scalloped. In early juveniles, the frill margin becomes ornamented by 17-19 delta-shaped epoccipitals. Epoccipitals are dorsoventrally compressed in subadults, strongly compressed and elongated in adults and ultimately merge onto the posterior frill margin in older adults. Ontogenetic trends within and between growth stages include: posterior frill margin transitions from scalloped to wavy and smooth; progressive exclusion of the supraoccipital from the foramen magnum; internal hollowing at the base of the postorbital horns; closure of the midline nasal suture; fusion of the epinasal onto the nasals; and epinasal expansion into a morphologically variable nasal horn. We hypothesize that the changes in horn orientation and epoccipital shape function to allow visual identity of juveniles, and signal their attainment of sexual maturity.

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Section: Resultsmentioning

confidence: 98%

Major cranial changes during Triceratops ontogeny

2006

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“…Anchiceratops (Mallon and Holmes 2010), and Chasmosaurus (RH, pers. obs., although there appears to be some variability in the course of the ridge in the latter genus), but is distinct from the condition in Triceratops (Hatcher et al 1907) and Torosaurus (Johnson and Ostrom 1995), in which the ridge terminates posteriorly midway between the dorsal and ventral margins of the blade. Both coracoids are preserved and essentially complete, but were folded under the body during dorsoventral compression of the carcass, obscuring details of the scapulocoracoid suture and coracoid foramen.…”

Section: Pectoral Girdle and Limbmentioning

confidence: 74%

“…The incomplete synsacrum includes two dorsosacrals, four sacral vertebrae bearing stout sacral ribs ('parapophyses' of Hatcher et al, 1907 andLull, 1933), two complete caudosacrals, and the anterior half of the third caudosacral (Figs. 9, 11).…”

Section: Synsacrummentioning

confidence: 99%

“…These ribs project posterolaterally, and expand distally to form the anterior portion of the buttress supporting the medial surface of the acetabular bar. A partial transverse process ('diapophysis' of Hatcher et al 1907 andLull 1933) is preserved only on the left side of the first sacral vertebra. A bony septum originating from the dorsal surface of the sacral rib sweeps posterodorsally to support the underside of this transverse process.…”

Section: Sacral Vertebrae and Ribs: Each Sacral Centrum Ismentioning

confidence: 99%

“…However, a proxy for the process lenght was made by measuring the distance from the distal margin of the articular facet to the tip of the process and dividing this by the total length of the ulna. This gives the following ratios: CMN 41357, 0.34; Triceratops (Hatcher et al 1907 Chasmosaurus and Pentaceratops overlap the centrosaurine range, which suggests the possibility that olecranon length is a variable character in ceratopsids and therefore of no taxonomic significance. The anterolateral process of the ulna does not present a triangular outline as it does in Chasmosaurus (Maidment and Barrett 2011) and Pentaceratops (Wiman 1930:plate 6), but rather forms a broadly rounded crest that extends for a considerable distance onto the lateral surface of the olecranon.…”

Section: Ulnamentioning

confidence: 99%

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The postcranial skeleton of Vagaceratops irvinensis (Dinosauria, Ceratopsidae)

Holmes

2014

Vert. Anat. Morph. Palaeo.

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Abstract:The postcranial skeleton of Vagaceratops (= Chasmosaurus) irvinensis (CMN 41357), lacking only the tail, most of the left front and left hind limbs, and portions of the pelvis, is preserved in articulation. It is one of the most complete, best articulated ceratopsid skeletons known. Both the manus and vertebral column exhibit conspicuous pathologies, possibly an indication of advanced age at the time of death. The vertebral column comprises a syncervical, six additional cervical vertebrae, and 12 dorsals. A partial synsacrum is represented by two dorsosacrals, four sacrals, two caudosacrals, and a partial third caudosacral centrum. The ribcage, although crushed, is nearly complete. The sternum is unusually wide compared with other ceratopsids. As in other chasmosaurines, the humerus bears a prominent deltopectoral crest that forms the anterior edge of the broad, rectangular proximal humeral expansion. The medial tuberosity is separated from the dorsal surface of the humerus by a distinct notch. The insertion for the latissimus dorsi is conspicuous. The deltopectoral crest extends a full half of the distance to the distal end of the humerus. Epipodials of the forelimb are relatively short compared to the corresponding propodial. The ulna has a long, distinctly triangular olecranon, broadly rounded anterolateral process, prominent medial process, and a deeply concave trochlear notch. The terminal phalanges on the fourth and fifth manual digits are relatively large, and unlike other ceratopsids have distinct distal (possibly articular) facets. The fourth trochanter of the femur is relatively proximal in position. This study and other recent studies of ceratopsid postcrania suggest that potentially useful taxonomic variation is present in the number of dorsosacrals, size of the groove on the ventral surface of the sacrum, morphology of the last dorsal and dorsosacral ribs, morphology of the scapula and proximal expansion of the humerus, morphology of the ulna, ratio of humerus/epipodium, morphology of the fifth manual digit, and position of the fourth trochanter of the femur.

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Jaw Mechanics in Basal Ceratopsia (Ornithischia, Dinosauria)

Tanoue

Grandstaff

You

et al. 2009

The Anatomical Record

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Ceratopsian dinosaurs were a dominant group of herbivores in Cretaceous terrestrial ecosystems. We hypothesize that an understanding of the feeding system will provide important insight into the evolutionary success of these animals. The mandibular mechanics of eight genera of basal ceratopsians was examined to understand the variability in shape of the jaws and the early evolution of the masticatory system in Ceratopsia. Data were collected on lever arms, cranial angles and tooth row lengths. The results indicate that psittacosaurids had higher leverage at the beak and in the rostral part of the tooth row than basal neoceratopsians, but lower leverage in the caudal part of the tooth row. Although the vertebrate mandible is generally considered as a third-class lever, that of basal neoceratopsians acted as a second-class lever at the caudal part of the tooth row, as is also true in ceratopsids. When total input force from the mandibular adductor muscles on both sides of the skull is considered, the largest bite force in basal ceratopsian tooth rows was exerted in the caudal part of the tooth row at the caudal extremity of the zone with near-maximum input force. Medially positioned teeth generate higher leverage than laterally positioned teeth. The largest bite force in all basal ceratopsians is smaller than the maximum input force, a limit imposed by the morphology of the basal ceratopsian masticatory system. In ceratopsids, caudal extension of the tooth row resulted in a much larger bite force, even exceeding the maximum input force. Anat Rec, 292:1352Rec, 292: -1369Rec, 292: , 2009. V V C 2009 Wiley-Liss, Inc.

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The Ceratopsia,

Cited by 67 publications

References 0 publications

Major cranial changes during Triceratops ontogeny

Major cranial changes during Triceratops ontogeny

The postcranial skeleton of Vagaceratops irvinensis (Dinosauria, Ceratopsidae)

Jaw Mechanics in Basal Ceratopsia (Ornithischia, Dinosauria)

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