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Chasmosaurus
Taxonomy
Chasmosaurus was named by Lambe (1914). It is the type genus of Chasmosaurinae.
It was synonymized subjectively with Ceratops by Gregory and Mook (1925).
It was assigned to Monocloniinae by Nopcsa (1928) and Huene (1950); to Ceratopsinae by Tatarinov (1964); to Ceratopinae by Olshevsky and Ford (1994); to Ceratopsidae by Abel (1924), Huene (1927), Hay (1930), Russell (1930), Lull (1933), Parks (1935), Gilmore (1935), Sternberg (1940), Sternberg (1949), Romer (1956), Parsch (1963), Kuhn (1964), Romer (1966), Charig (1967), Swinton (1970), Powell (1973), Molnar (1980), Lehman (1981), Dodson (1983), Russell (1984), Ostrom and Wellnhofer (1986), Clemens (1986), Carroll (1988) and Longrich (2008); and to Chasmosaurinae by Lambe (1915), Lehman (1989), Dodson and Currie (1990), Lehman (1990), Forster and Sereno (1993), Godfrey and Holmes (1995), Lehman (1996), Vickaryous and Ryan (1997), Dodson (1997), Dodson (1997), Eberth et al. (2001), Dodson et al. (2004), Farke (2004), Diem and Archibald (2005), Ryan and Evans (2005), Lucas et al. (2006), Wu et al. (2007), Ryan (2007), Hunt and Lehman (2008), Longrich (2010), Xu et al. (2010), Ryan et al. (2010), Maidment and Barrett (2011), Farke et al. (2011), Farke (2011), Fiorillo and Tykoski (2012), Longrich (2014), Konishi (2015), Evans and Ryan (2015) and Campbell et al. (2016).
It was synonymized subjectively with Ceratops by Gregory and Mook (1925).
It was assigned to Monocloniinae by Nopcsa (1928) and Huene (1950); to Ceratopsinae by Tatarinov (1964); to Ceratopinae by Olshevsky and Ford (1994); to Ceratopsidae by Abel (1924), Huene (1927), Hay (1930), Russell (1930), Lull (1933), Parks (1935), Gilmore (1935), Sternberg (1940), Sternberg (1949), Romer (1956), Parsch (1963), Kuhn (1964), Romer (1966), Charig (1967), Swinton (1970), Powell (1973), Molnar (1980), Lehman (1981), Dodson (1983), Russell (1984), Ostrom and Wellnhofer (1986), Clemens (1986), Carroll (1988) and Longrich (2008); and to Chasmosaurinae by Lambe (1915), Lehman (1989), Dodson and Currie (1990), Lehman (1990), Forster and Sereno (1993), Godfrey and Holmes (1995), Lehman (1996), Vickaryous and Ryan (1997), Dodson (1997), Dodson (1997), Eberth et al. (2001), Dodson et al. (2004), Farke (2004), Diem and Archibald (2005), Ryan and Evans (2005), Lucas et al. (2006), Wu et al. (2007), Ryan (2007), Hunt and Lehman (2008), Longrich (2010), Xu et al. (2010), Ryan et al. (2010), Maidment and Barrett (2011), Farke et al. (2011), Farke (2011), Fiorillo and Tykoski (2012), Longrich (2014), Konishi (2015), Evans and Ryan (2015) and Campbell et al. (2016).
Synonyms
Synonymy list
| Year | Name and author |
|---|---|
| 1902 | Monoclonius canadensis Lambe p. 63 figs. Pl. 17-18 |
| 1905 | Monoclonius canadensis Lambe p. 3 |
| 1907 | Ceratops canadensis Hatcher et al. p. 172 |
| 1914 | Ceratops canadensis Brown p. 378 |
| 1914 | Protorosaurus Lambe p. 131 |
| 1914 | Monoclonius canadensis Lambe p. 132 |
| 1914 | Chasmosaurus Lambe pp. 149-155 |
| 1914 | Ceratops canadensis Lambe p. 154 |
| 1915 | Eoceratops Lambe p. 1 figs. Pl. 1-2 |
| 1915 | Eoceratops canadensis Lambe p. 1 |
| 1915 | Chasmosaurus Lambe p. 20 |
| 1915 | Eoceratops Lambe p. 20 |
| 1915 | Eoceratops canadensis Lambe p. 117 |
| 1916 | Eoceratops canadensis Lambe p. 194 |
| 1922 | Eoceratops Joleaud p. 64 |
| 1923 | Eoceratops canadensis Gilmore p. 51 |
| 1924 | Chasmosaurus Abel p. 712 |
| 1924 | Eoceratops Abel p. 712 |
| 1925 | Eoceratops canadensis Parks p. 5 |
| 1927 | Ceratops caudensis Huene p. 261 |
| 1927 | Chasmosaurus Huene p. 261 |
| 1927 | Eoceratops Huene p. 261 |
| 1928 | Chasmasaurus Nopcsa p. 185 |
| 1928 | Eoceratops Nopcsa p. 185 |
| 1930 | Eoceratops Hay p. 221 |
| 1930 | Eoceratops canadensis Hay p. 221 |
| 1930 | Chasmosaurus Hay p. 223 |
| 1930 | Chasmosaurus Russell p. 149 |
| 1930 | Eoceratops Russell p. 149 |
| 1930 | Eoceratops canadensis Russell p. 149 |
| 1933 | Chasmosaurus kaiseni Brown |
| 1933 | Eoceratops Lull p. 91 |
| 1933 | Eoceratops canadensis Lull p. 91 |
| 1933 | Chasmosaurus Lull p. 92 |
| 1933 | Chasmosaurus brevirostris Lull p. 94 figs. Pl. VIIA |
| 1933 | Chasmosaurus kaiseni Lull p. 94 fig. 38 |
| 1935 | Chasmosaurus Gilmore p. 164 |
| 1935 | Chasmosaurus Parks p. 193 |
| 1935 | Chasmosaurus brevirostris Parks p. 193 |
| 1939 | Chasmosaurus kaiseni Riabinin p. 25 |
| 1940 | Eoceratops canadensis Sternberg p. 471 |
| 1940 | Chasmosaurus Sternberg p. 478 |
| 1940 | Chasmosaurus brevirostris Sternberg p. 478 |
| 1946 | Chasmosaurus kaiseni Gray p. 796 |
| 1946 | Chasmosaurus brevirostris Gray p. 797 |
| 1949 | Chasmosaurus brevirostris Lull and Gray p. 493 |
| 1949 | Chasmosaurus Sternberg p. 41 fig. 1 |
| 1949 | Eoceratops Sternberg p. 41 fig. 1 |
| 1949 | Chasmosaurus kaiseni Sternberg p. 42 fig. 1 |
| 1950 | Chasmosaurus Huene p. 351 |
| 1950 | Eoceratops Huene p. 351 |
| 1956 | Chasmosaurus Romer p. 639 |
| 1956 | Eoceratops Romer p. 639 |
| 1963 | Chasmosaurus Parsch p. 8 |
| 1963 | Eoceratops Parsch p. 8 |
| 1964 | Chasmosaurus Kuhn p. 56 |
| 1964 | Chasmosaurus brevirostris Kuhn p. 56 |
| 1964 | Chasmosaurus kaiseni Kuhn p. 56 |
| 1964 | Eoceratops Kuhn p. 56 |
| 1964 | Eoceratops canadensis Kuhn p. 56 |
| 1964 | Chasmosaurus kaiseni Russell p. 13 |
| 1964 | Eoceratops canadensis Russell p. 13 |
| 1964 | Eoceratops Tatarinov p. 583 |
| 1964 | Eoceratops canadensis Tatarinov p. 583 |
| 1964 | Chasmosaurus Tatarinov p. 585 |
| 1966 | Chasmosaurus Romer p. 371 |
| 1966 | Eoceratops Romer p. 371 |
| 1966 | Chasmosaurus kaiseni Russell p. 21 |
| 1966 | Chasmosaurus brevirostris Russell p. 30 |
| 1967 | Chasmosaurus Charig p. 717 |
| 1967 | Eoceratops Charig p. 717 |
| 1967 | Eoceratops canadensis Charig p. 717 |
| 1970 | Chasmosaurus Swinton p. 259 |
| 1973 | Chasmosaurus Powell p. 118 |
| 1975 | Eoceratops canadensis Langston p. 1585 |
| 1980 | Chasmosaurus Molnar p. 138 |
| 1981 | Eoceratops Lehman p. 209 |
| 1981 | Eoceratops canadensis Lehman p. 209 |
| 1981 | Chasmosaurus Lehman p. 214 |
| 1981 | Chasmosaurus kaiseni Tyson p. 1244 |
| 1983 | Chasmosaurus Dodson p. 94 |
| 1983 | Eoceratops Dodson p. 94 |
| 1984 | Chasmosaurus Russell p. 25 |
| 1984 | Eoceratops Russell p. 25 |
| 1985 | Chasmosaurus kaiseni Sloan p. 265 |
| 1986 | Chasmosaurus Clemens p. 80 |
| 1986 | Eoceratops Clemens p. 80 |
| 1986 | Chasmosaurus Ostrom and Wellnhofer p. 116 |
| 1986 | Eoceratops Ostrom and Wellnhofer p. 116 |
| 1986 | Chasmosaurus brevirostris Tokaryk p. 195 |
| 1988 | Chasmosaurus Carroll |
| 1988 | Eoceratops Carroll |
| 1989 | Chasmosaurus Lehman p. 138 |
| 1989 | Chasmosaurus canadensis Lehman p. 139 |
| 1990 | Chasmosaurus Dodson and Currie p. 612 |
| 1990 | Chasmosaurus canadensis Dodson and Currie p. 612 |
| 1990 | Chasmosaurus Lehman p. 212 |
| 1990 | Chasmosaurus canadensis Lehman p. 224 |
| 1993 | Chasmosaurus Forster and Sereno p. 14 |
| 1993 | Chasmosaurus canadensis Lehman p. 284 |
| 1994 | Chasmosaurus Olshevsky and Ford |
| 1995 | Chasmosaurus Godfrey and Holmes p. 727 |
| 1996 | Chasmosaurus Lehman p. 505 fig. 10 |
| 1996 | Chasmosaurus canadensis Lehman p. 505 fig. 10 |
| 1997 | Chasmosaurus Dodson p. 12 |
| 1997 | Chasmosaurus Vickaryous and Ryan p. 492 |
| 2001 | Chasmosaurus Eberth et al. p. 59 |
| 2004 | Chasmosaurus Dodson et al. p. 495 |
| 2004 | Chasmosaurus Farke p. 4 |
| 2005 | Chasmosaurus Diem and Archibald p. 251 |
| 2005 | Chasmosaurus Ryan and Evans p. 325 |
| 2006 | Chasmosaurus Lucas et al. p. 368 |
| 2007 | Chasmosaurus Ryan p. 391 fig. 12 |
| 2007 | Chasmosaurus Wu et al. p. 1261 fig. 14 |
| 2008 | Chasmosaurus Hunt and Lehman p. 1132 |
| 2008 | Chasmosaurus Longrich p. 994 |
| 2010 | Chasmosaurus Longrich pp. 682-683 |
| 2010 | Mojoceratops Longrich p. 682–683 fig. 10 |
| 2010 | Chasmosaurus Ryan et al. p. 185 |
| 2010 | Chasmosaurus Xu et al. p. 1634 fig. 3 |
| 2011 | Chasmosaurus Farke p. 5 |
| 2011 | Mojoceratops Farke p. 5 |
| 2011 | Chasmosaurus Farke et al. p. 699 |
| 2011 | Chasmosaurus Maidment and Barrett p. 4 |
| 2012 | Chasmosaurus Fiorillo and Tykoski |
| 2014 | Chasmosaurus Longrich p. 303 fig. 8 |
| 2014 | Mojoceratops Longrich p. 303 fig. 8 |
| 2015 | Chasmosaurus Evans and Ryan |
| 2015 | Chasmosaurus Konishi p. 610 |
| 2016 | Chasmosaurus Campbell et al. p. 34 |
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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.
G. †Chasmosaurus Lambe 1914
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†Chasmosaurus belli Lambe 1902
†Chasmosaurus russelli Sternberg 1940
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Invalid names: Mojoceratops perifania Longrich 2010 [synonym]
Invalid names: Chasmosaurus brevirostris Lull 1933 [nomen dubium], Chasmosaurus kaiseni Brown 1933 [nomen dubium], Eoceratops Lambe 1915 [synonym], Mojoceratops Longrich 2010 [synonym], Monoclonius canadensis Lambe 1902 [nomen dubium], Protorosaurus Lambe 1914 [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| N. R. Longrich 2010 | Chasmosaurine ceratopsid characterized by the following combination of characters: (1) supraorbital horns reduced (length no more than 200% of basal diameter in adults) or absent; (2) parietal epoccipitals 1 and 2 both upturned and curving forward; (3) parietal caudal rami dorsoventrally compressed and strap-like, with a thickened caudal rim; (4) parietals subequal to squamosals in length, (5) epijugal small, often low and button-like; (6) parietal caudal emargination weakly developed, angle between lateral rami of parietal caudal bar at least 120°, (7) supraorbital horns oriented anterodorsally, (8) frill not erect, long axis of parietal median bar forming an angle of about 30° to the horizontal. | |
| N. R. Longrich 2010 (Mojoceratops) | As for type and only species. | |
| S. C. R. Maidment and P. M. Barrett 2011 | Chasmosaurus is diagnosed based on the following combination of characters: (1) Premaxillary flange along entire anterior margin of external naris; (2) supraorbital horns, when present, curve posteriorly along their length; (3) frill broadens posteriorly to form triangular shield with maximum width more than twice the skull width at orbits; (4) medial margin of squamosal, where it articulates with the lateral bar of the parietal, straight; (5) parietal fenestrae large, occupying most of the parietal, and being rounded or anteroposteriorly longer than transversely wide; (6) epiparietals triangular in shape and project posteriorly or dorsally but do not curve anteriorly. Characters 1–3 after Forster et al. (1993). All of these features are seen in other chasmosaurines and do not, therefore, represent autapomorphies, but this combination of features appears to be unique to Chasmosaurus. See discussion for more details. | |
| T. Konishi 2015 | From Maidment and Barrett (2011, p. 4): (1) Premaxillary flange along entire anterior margin of external naris; (2) supraorbital horns, when present, curve posteriorly along their length; (3) frill broadens posteriorly to form triangular shield with maximum width more than twice the skull width at orbits; (4) medial margin of squamosal, where it articulates with the lateral bar of the parietal, straight; (5) parietal fenestrae large, occupying most of the parietal, and being rounded or anteroposteriorly longer than transversely wide; (6) epiparietals triangular in shape and project posteriorly or dorsally but do not curve anteriorly. In addition to these, I propose the following new character: (7) squamosal dorsal border laterally adjacent to supratemporal fenestra straight in profile, anteriorly at level with base of postorbital horncore, and sloping posteroventrally at a shallow angle before ascending farther posteriorly to form lateral border of parietal fenestra. Like the other six characters, the last character is not an autapomorphy for Chasmosaurus among chasmosaurines (Maidment and Barrett 2011). The combination of characters 2 and 7 uniquely diagnoses Chasmosaurus, as Agujaceratops Lucas et al., 2006 is the only other chasmosaurine genus to possess character 2, yet in the latter the dorsal squamosal border lateral to the supratemporal fenestra ascends posteriorly instead (Forster et al. 1993, fig. 3). The polarity of character 7 within Chasmosaurinae is presently unknown. | |
| J. A. Campbell et al. 2016 | Chasmosaurus is diagnosed based on the following unique combination of characters: (1) Premaxillary flange along entire anterior margin of external naris; (2) postorbital horncores, when present, curve posteriorly along their length; (3) squamosal dorsal border laterally adjacent to dorsal temporal fenestra straight in profile, anteriorly at level with base of postorbital horncore, and sloping posteroventrally at a shallow angle before ascending farther posteriorly to form lateral border of parietal fenestra; (4) medial margin of squamosal, where it articulates with the lateral bar of the parietal, straight; (5) frill broadens posteriorly to form rectangular to triangular shield with maximum width more than twice the skull width at orbits; (6) parietal fenestrae large, occupying most of the parietal, and being rounded or anteroposteriorly longer than transversely wide; and (7) epiparietals straight and triangular in shape and oriented posteriorly or anterodorsally. |
Measurements
No measurements are available
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| Source: g = genus, subo = suborder, o = order | |||||
| References: Marsh 1875, Peczkis 1995, Norman and Weishampel 1991 | |||||
Age range: base of the Late/Upper Campanian to the top of the Campanian or 83.50000 to 72.10000 Ma
Collections (21 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Campanian | Canada (Alberta) | C. russelli (64401) | |
| Late/Upper Campanian | Canada (Alberta) | C. belli (45730 45731 58909 58954 59047 191258) C. brevirostris (58912) C. kaiseni (35379) C. russelli (64400) C. sp. (22656 22659 59006 59014 59136 191255) Eoceratops canadensis (59026) Monoclonius belli (60873) | |
| Middle Campanian - Late/Upper Campanian | Canada (Alberta) | C. russelli (64402) Monoclonius canadensis (60874) | |
| Middle Campanian - Late/Upper Campanian | USA (Montana) | C. sp. (50907) |