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Ceratosaurus nasicornis

Reptilia -

Ceratosaurus nasicornis was named by Marsh (1884). Its type specimen is USNM 4735, a skeleton, and it is a 3D body fossil. Its type locality is Felch Quarry 1, Garden Park (YPM), which is in a Kimmeridgian/Tithonian channel sandstone/claystone in the Morrison Formation of Colorado. It is the type species of Ceratosaurus.

It was recombined as Megalosaurus nasicornis by Cope (1892).

Synonymy list
YearName and author
1884Ceratosaurus nasicornis Marsh p. 330 figs. Pl. 8-14
1884Ceratosaurus nasicornis Vetter p. 357
1885Ceratosaurus nasicornis Woodward p. 12
1890Ceratosaurus nasicornis Gaudry p. 233
1890Ceratosaurus nasicornis Zittel p. 727
1891Ceratosaurus nasicornis Boule p. 19
1892Megalosaurus nasicornis Cope pp. 241-245
1893Ceratosaurus nasicornis Marsh p. 437
1896Ceratosaurus nasicornis Marsh p. 157
1898Ceratosaurus nasicornis Woodward p. 200
1899Ceratosaurus nasicornis Knight p. 22
1900Ceratosaurus nasicornis Walcott p. 23
1902Ceratosaurus nasicornis Hay p. 494
1902Ceratosaurus nascomis Mansel-Pleydell p. lxxviii
1903Ceratosaurus nasicornis Lambe p. 134
1904Ceratosaurus nasicornis Lambe p. 5
1911Ceratosaurus nasicornis von Zittel p. 281
1913Ceratosaurus nasicornis Tornier p. 369 fig. 47–48
1915Ceratosaurus nasicornis Nopcsa p. 388
1915Ceratosaurus nasicornis Stromer p. 7
1920Ceratosaurus nasicornis Gilmore pp. 76-77
1933Ceratosaurus nasicornis Janensch p. 232
1934Ceratosaurus nasicornis Stromer p. 78
1934Ceratosaurus nasicornis Swinton p. 31
1935Ceratosaurus nasicornis Lowe p. 418
1964Ceratosaurus nasicornis Tatarinov p. 538
1970Ceratosaurus nasicornis Steel p. 30
1970Ceratosaurus nasicornis Swinton p. 139
1972Ceratosaurus nasicornis Osmólska et al. p. 137
1974Ceratosaurus nasicornis Molnar p. 1012
1977Ceratosaurus nasicornis Anonymous p. 16
1980Ceratosaurus nasicornis Molnar and Pledge p. 285 fig. 3
1981Ceratosaurus nasicornis McIntosh p. 8
1981Ceratosaurus nasicornis Osmolska p. 90
1984Ceratosaurus nasicornis Jensen p. 375
1984Ceratosaurus nasicornis Welles pp. 156-158
1986Ceratosaurus nasicornis Gauthier p. 9
1988Ceratosaurus nasicornis Paul pp. 275-276
1989Ceratosaurus nasicornis Rowe p. 125
1990Ceratosaurus nasicornis Rowe and Gauthier p. 152
1991Ceratosaurus nasicornis Bonaparte p. 18
1991Ceratosaurus nasicornis Molnar p. 165
1992Ceratosaurus nasicornis Bakker et al. p. 9 fig. 3D
1996Ceratosaurus nasicornis Richmond and Stadtman p. 117
1997Ceratosaurus nasicornis Carpenter p. 91
1997Ceratosaurus nasicornis Novas p. 1
1997Ceratosaurus nasicornis Rowe et al. p. 106
1997Ceratosaurus nasicornis Vickaryous and Ryan p. 488
1998Ceratosaurus nasicornis Holtz, Jr. p. 38
2000Ceratosaurus nasicornis Foster and Chure p. 8 fig. 3
2000Ceratosaurus dentisulcatus Madsen Jr. and Welles
2000Ceratosaurus magnicornis Madsen Jr. and Welles p. 2
2003Ceratosaurus nasicornis Rauhut p. 24
2003Ceratosaurus dentisulcatus Yates p. 320
2004Ceratosaurus dentisulcatus Tykoski and Rowe p. 49
2004Ceratosaurus magnicornis Tykoski and Rowe p. 49
2004Ceratosaurus nasicornis Tykoski and Rowe p. 49
2005Ceratosaurus nasicornis Yates p. 105
2005Ceratosaurus dentisulcatus Yates p. 109
2005Ceratosaurus magnicornis Yates p. 114
2006Ceratosaurus dentisulcatus Chure et al. p. 236
2006Ceratosaurus magnicornis Chure et al. p. 236
2006Ceratosaurus nasicornis Chure et al. p. 236
2006Ceratosaurus nasicornis Hunt and Lucas p. 117
2006Ceratosaurus magnicornis Langer and Benton p. 320 fig. 5
2006Ceratosaurus dentisulcatus Mateus p. 226
2006Ceratosaurus magnicornis Mateus p. 226
2006Ceratosaurus nasicornis Mateus p. 226
2006Ceratosaurus dentisulcatus Mateus et al. pp. 123-124
2006Ceratosaurus magnicornis Mateus et al. p. 124
2006Ceratosaurus nasicornis Mateus et al. p. 124
2007Ceratosaurus nasicornis Sampson and Witmer p. 33
2007Ceratosaurus dentisulcatus Smith p. 104
2008Ceratosaurus nasicornis Carrano and Sampson p. 192
2008Ceratosaurus dentisulcatus Soto and Perea p. 441
2008Ceratosaurus magnicornis Soto and Perea p. 441
2008Ceratosaurus nasicornis Soto and Perea p. 441
2010Ceratosaurus nasicornis Paulina Carabajal and Canale p. 249
2010Ceratosaurus nasicornis Rauhut et al. p. 156
2011Ceratosaurus nasicornis Hone et al. p. 502
2011Ceratosaurus nasicornis Ruiz et al. p. 1271
2012Ceratosaurus nasicornis Carrano et al. p. 226
2012Ceratosaurus nasicornis Paulina Carabajal and Currie p. 86
2016Ceratosaurus magnicornis Foster et al. p. 45
2016Ceratosaurus nasicornis Martill et al. p. 33
2018Ceratosaurus dentisulcatus Rauhut et al. p. 18
2018Ceratosaurus nasicornis Rauhut et al. p. 18

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phylumChordataHaeckel 1847
subclassDipnotetrapodomorpha(Nelson 2006)
SauriaGauthier 1984
Archosauromorpha(Huene 1946)
ArchosauriformesGauthier 1986
AverostraPaul 2002

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

J. H. Madsen and S. P. Welles 2000 (Ceratosaurus magnicornis)Differs from Ceratosaurus nasicornis in being more massive; having a longer and lower skull (H:Lratio of 40 versus 47); the anterior border of the premaxilla is straighter; the maxilla is longer (412 versus 360 mm); its anterior edge is almost vertical, versus an anterior dip of about 50°; its lower border is more convex, its lateral face more deeply impressed by the recess, and its nasal process has a deep maxillary vacuity; the upper edge of the maxilla, below the antorbital fenestra, dips only 15° posteriorly versus 25°, and the anterior edge of the maxilla is lower at the front of the fenestra; the nasal horn core is longer and lower; the teeth are longer and stouter, especially posteriorly; the lacrimal is more massive, bears a high, rugose horn core with a longer base, and a much larger recess; the quadratojugal is more massive ventrally; the quadrate has a much larger, lower articular surface, and its pillar is more concave posteriorly; the dentary is much more concave dorsally and convex ventrally, the chin much more rounded with the bone more massive, becoming 148 mm high at the surangular contact at 546 mm from the chin, versus 92 mm at 320 mm; there are 11, possibly 12 alveoli versus 15. The 6th cervical is 80 mm long versus 65 mm, and its neural spine is much higher (145 versus 120 mm) and is longer anteroposteriorly (52 versus 34 mm); the table slants up more steeply posteriorly; the posterior chonos is much shorter; the diapophysis is much higher above the parapophysis; there is a stout epipophysis. The femur is 630 mm long versus 620 mm, its head 120 mm broad versus 150 mm, and the distal end of each is 135 mm broad; the shaft is 75 mm broad below the trochanteric shelf, versus 52 mm, and is much straighter. The tibia is 520 mm long versus 555 mm (T:F ratio of 83 versus 90) and the tuberosity is not so well developed; the proximal diameters are 135 and 180 mm, the distal are diameters 132 and 140 mm; the astragalar facet is similar, but the dorsal process of the astragalus completely fills the facet. The calcaneum is broader anteriorly, occupying 43% of the astragalocalcanear breadth, versus 28%, and the suture runs dorsolaterally; the calcaneum is also broader in lateral view. For differences from Ceratosaurus dentisulcatus, n. sp. see the diagnosis for that species on page 21.
J. H. Madsen and S. P. Welles 2000 (Ceratosaurus dentisulcatus)In addition to significantly larger size, the largest ceratosaur of record differs from Ceratosaurus nasicornis in the following: subnarial border of premaxilla arched and almost horizontal versus straight and dipping forward; nasal process lower; body of premaxilla longer, and with several large foramina; maxilla more massive, alveolar border more concave, and recess more pronounced; posterior edge of nasal process rises more steeply; front of antorbital fenestra more open; three large openings into body of maxilla at front of maxillary recess and base of nasal process; 12 alveoli versus 15; teeth more massive and more strongly recurved; dentary more massive and more upturned from tooth 6 forward; dentary teeth more massive, and only 11 versus 15; atlas-axis 100 mm long versus 84; odontoid more prominent, axial centrum much shorter, its ventral edge less downcurved, its spine higher and very much shorter anteroposteriorly, its anterior edge dipping 70° anteriorly versus 20°; the edge of its table much steeper and straighter, there is no prezygapophysis and there is an epipophysis extending far behind the spine; third centrum shorter, its ends almost vertical, its spine shorter and almost vertical rather than strongly recurved, its epipophysis very much larger; tibia longer (594 versus 554 mm) and more massive; the tuberosity heavier, as is the shaft; the astragalar overhang dips only 5° versus 28°; the distal end is 165 mm broad versus 140 mm; there is a weak horizontal groove across the front of the astragalus, and its dorsal process is ossified; the fibula is longer (564 versus 502 mm); in lateral view its upper end is vertical, rather than dipping 70° anteriorly, and is broader; the tibial flange dips posteriorly versus anteriorly, and its upper edge versus lower edge projects anteriorly; the distal end is broader (81 versus 53 mm) and is convex, evenly rounded versus truncated. It differs from Ceratosaurus magnicornis, n. sp. in having a much more massive premaxilla; the muzzle is more
rounded and the nasal process curves back more sharply, making the snout and naris lower; the lower border of the naris is convex behind an anterior concavity, as opposed to
smoothly concave; the maxilla is about the same length, but has a steeper nasal process with a straight posterior border so the antorbital fenestra has a more open anterior border; there are three additional openings into the maxilla at the front of the recess and the base of the nasal process; the lateral face of the bone is higher above the first three teeth; the lower half of the anterior border dips steeply posteriorly, versus anteriorly; the alveolar border is slightly more convex; the foramina in the row above the alveolar border are larger, and the grooves below them deeper; the anterior three teeth are more recurved, and the posterior teeth more vertical. The 5th cervical vertebra has a similarly downset centrum, but is shorter; the transverse process ends with the diapophysis higher above the parapophysis; the table is shorter; the epipophysis much smaller; the spine is lower, shorter, and the shoulder weaker. The humerus is longer (333 versus 292 mm) and is much more massive; the head dips only 10° laterally versus 20° and the anteroventral process of the greater tuberosity is much larger; the deltoid tuberosity is 93 mm long, versus 84 mm, and is thinner; the shaft is 63 mm broad versus 35 mm.
M. T. Carrano and S. D. Sampson 2008Ceratosaur with: (1) mediolaterally narrow, rounded midline horn core on the fused nasals, (2) medial oval groove on nasals behind horn core, (3) pubis with large, rounded notch underneath the obturator foramen, (4) small median dorsal osteoderms (modified from Rauhut 2003: 24).
M. T. Carrano et al. 2012Ceratosaur with: (1) mediolaterally narrow, rounded midline horn core on nasals, fused in adults (modified from Marsh 1884); (2) medial oval groove on nasals behind horn core (Rauhut 2003); (3) pubis with large, rounded notch ventral to obturator foramen (Rauhut 2003); and (4) small median dorsal osteoderms (Marsh 1884).