Editing Chasmosaurus (section)

{{Short description|Extinct genus of dinosaurs}}
{{Automatic taxobox
| fossil_range = [[Late Cretaceous]] ([[Campanian]]), {{fossilrange|77|74}}
| image = ChasmosaurusROM.JPG
| image_caption = ''C. belli'' skeleton, [[Royal Ontario Museum]] specimen 843
| taxon = Chasmosaurus
| authority = [[Lawrence Lambe|Lambe]], [[1914 in paleontology|1914]]
| subdivision_ranks = Species
| subdivision = *{{extinct}}'''''C. belli''''' <small>(Lambe, [[1902 in paleontology|1902]]) [originally ''[[Monoclonius]] belli'', [[type species|type]]]</small>
*{{extinct}}'''''C. russelli''''' <small>[[Charles Mortram Sternberg|Sternberg]], [[1940 in paleontology|1940]]</small>
*{{extinct}}'''''[[Vagaceratops|C. irvinensis]]'''''? <small>Holmes ''et al.'', [[2001 in paleontology|2001]]</small>
| synonyms = *''Eoceratops'' <small>Lambe, [[1915 in paleontology|1915]]</small>
*''Mojoceratops'' <small>Longrich, [[2010 in paleontology|2010]]</small>
*''[[Vagaceratops]]''? <small>Sampson ''et al.'', 2010</small>
}}

'''''Chasmosaurus''''' ({{IPAc-en|ˌ|k|æ|z|m|oʊ|ˈ|s|ɔːr|ə|s}} {{respell|KAZ|moh|SOR|əs}}) is a [[genus]] of [[Ceratopsidae|ceratopsid]] [[dinosaur]] from the Late [[Cretaceous]] [[Period (geology)|Period]] in [[North America]]. Its given name means 'opening lizard', referring to the large openings ([[Fenestra (anatomy)|fenestrae]]) in its frill ([[Ancient Greek|Greek]] ''chasma'', meaning 'opening', 'hollow', or 'gulf'; and ''sauros'', meaning 'lizard'). With a length of {{convert|4.3|-|4.8|m|ft|1|lk=on}} and a weight of {{convert|1.5|-|2|t|short ton|lk=on}}—or anywhere from 2,200 to nearly 5,000 lbs., give or take—''Chasmosaurus'' was of a slightly smaller to ‘average’ size, especially when compared to larger ceratopsians (such as ''[[Triceratops]]'', which were about the size of an [[African bush elephant]]).

It was initially to be called ''Protorosaurus'', but this name had been previously published for another animal. All of the excavated specimens of ''Chasmosaurus'' were collected at the [[Dinosaur Park Formation]], [[Dinosaur Provincial Park]], [[Alberta, Canada]]. Referred specimens of ''C. russelli'' come from the lower beds of the formation, while ''C. belli'' comes from the middle and upper beds.<ref name="Ornithischian">{{cite book |chapter=Ornithischian dinosaurs |title=Dinosaur Provincial Park: A Spectacular Ecosystem Revealed |author=Ryan, M.J. |author2=Evans, D.C. |name-list-style=amp |year=2005 |editor=Currie, P.J. |editor2=Koppelhus, E.B. |publisher=Indiana University Press |location=Bloomington |pages=312–348 }}</ref>