[D] Chirostenotes elegans
Describer
Sues, 1997
Time
Cretaceous Late Campanian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Oviraptorosauria Caenagnathidae
Diet
Carnivore
Fossilsite
Red Deer River, Oldman Formation, Judith River Group (Wedge), Alberta, Canada
Fall Under
Chirostenotes
Info
Chirostenotes (Gilmore, 1924) > Chirostenotes pergracilis (Gilmore, 1924) >> Macrophalangia canadensis (Sternberg, 1932) |> Chirostenotes elegans (Sues, 1997) > Elmisaurus elegans (Parks, 1933) >> Ornithomimus elegans (Parks, 1933)
ROM 00781 Holotype, Metatarsal II; Metatarsal IV; complete; Metatarsal III; incomplete; Left
Osmolska (1981) created the family Elmisauridae because of the similariteis between Chirostenotes and Elmisaurus. However Sues in 1997 in \\\" On Chirostenotes, a Late Cretaceous oviraptorosaur (Dinosauria: Theropoda) from western North America Journal of Vertebrate Paleontology, 1997, 17(4):698-716 \\\" described a previously unrecognized partial skeleton ROM 43250 of Chirostenotes pergracilis (Gilmore, 1924) from the Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada including parts of the skull, much of the pelvic girdle, and elements from all regions of the vertebral column.
According to Sues close structural correspondence between the maxilla of this specimen and the mandible of Caenagnathus collinsi R. M. Sternberg , 1940 indicates that the latter taxon should be considered a subjective junior synonym of Chirostenotes pergracilis and he also concluded that \\\'\\\'Ornithomimus\\\'\\\' elegans Parks, 1933 is probably also referable to Chirostenotes. He regarded the family-level taxon Elmisauridae Osmolska, 1981 as a subjective junior synonym of Caenagnathidae R. M. Sternberg, 1940.
Currie and Russell (1988) sorted the \\\"elmisaurid\\\" material then described from North America into two distinct morphs based on the morphology of the manus and pes: a \\\"robust\\\" morph (CMN 2367 [type of Chirostenotes pergracilis], CMN 8538 [type of Macrophalangia canadensis]) and a \\\"slender\\\" morph (ROM 781 [type of \\\'\\\'Ornithomimus\\\'\\\' elegans], RTMP 79.20.1) suggesting that the two morphs may represent the two sexes of a single dimorphic species and speculated that the mandibles named Caenagnathus collinsi and Caenagnathus sternbergi (which also differ in their relative slenderness) may also be referrable to these robust and slender morphs of Chirostenotes pergracilis, respectively.
Currie (1989, 1990) made ROM 781, an incomplete hindlimb, the holotype of his new combination, Elmisaurus elegans. ROM 781 was first described and named \\\'\\\'Ornithomimus\\\'\\\' elegans by Parks (1933). Russell (1972) had referred the material to Macrophalangia. Currie (1989) noted similarities between ROM 781 and theropod hindlimb bones from Mongolia named Elmisaurus rarus. These similarities included the degree of coossification of the tarsometatarsus (complete fusion of metatarsals II-IV with adjoing tarsals III and IV), a prominent proximolateral process on tarsal IV, and the proximal part of metatarsal III being triangular in section (not diamond-shaped, as in Chirostenotes pergracilis). Currie (1989) consequently removed ROM 781 from Chirostenotes pergracilis and made it the holotype of a second species of Elmisaurus, Elmisaurus elegans. Currie referred to this species two hitherto undescribed tarsometatarsi from Alberta which also showed this same pattern of coossification (RTMP 82.39.4, ROM 37163).
Sues did not include the degree of tarsometatarsal fusion as a defining character for Chirostenotes (and its included species), but instead employed much the same criteria that Currie and Russell (1988) had earlier used to distinguish two separate morphs of Chirostenotes pergracilis. In light of ROM 43250, Sues (1997) could confidently refer CMN 8776 to Chirostenotes pergracilis, thereby sinking Caenagnathus collinsi as a junior synonym of Chirostenotes pergracilis CMN 2367. Sues (1997) returned ROM 781 to the genus Chirostenotes as the holotype of a second species, Chirostenotes elegans. Sues also assumed that Chirostenotes elegans and Caenagnathus sternbergi (Cracraft, 1971) CMN 2690 represented the same species.
Chirostenotes elegans differs fromother species of Chirostenotes[=\\\"Caenagnathus\\\"] in having smaller adult size and articular with higher, more arched cranio-caudal ridge on articulating surface, medial glenoid that is relatively short anterocaudally (Cracraft, 1971), no wel developed chorda tympani foramen or slot (Varricchio, 2001) Chirostenotes pergracilis can be distinguished from Chirostenotes elegans by its more elongate and shallow dentary; a proportionately longer mandibular symphysis; and the presence of a median ridge on the dorsal edge of this symphysis. Chirostenotes pergracilis also appears to be a larger and (judging by the construction of the hand and foot bones) less gracile species than Chirostenotes elegans. (Sues, 1997)
Varricchio (2001) described a fragmentary lower jaw (MOR 1107), including the caudal end of the right mandibular ramus and referred the specimen to \\\"Caenagnathus sternbergi\\\" (=?Chirostenotes elegans) collected from the Upper Cretaceous (Campanian) Two Medicine Formation at Lanslide Butte, Clacier County, Montana.
Sources: Tim Williams pers comm.; Glut The Encyclopedia Sup. 3; Suez, (1997); The Dinosauria II; Mesozoic Vertbrate Lfie, (Tanke & CArpenter, (2001)
Sues, 1997
Time
Cretaceous Late Campanian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Oviraptorosauria Caenagnathidae
Diet
Carnivore
Fossilsite
Red Deer River, Oldman Formation, Judith River Group (Wedge), Alberta, Canada
Fall Under
Chirostenotes
Info
Chirostenotes (Gilmore, 1924) > Chirostenotes pergracilis (Gilmore, 1924) >> Macrophalangia canadensis (Sternberg, 1932) |> Chirostenotes elegans (Sues, 1997) > Elmisaurus elegans (Parks, 1933) >> Ornithomimus elegans (Parks, 1933)
ROM 00781 Holotype, Metatarsal II; Metatarsal IV; complete; Metatarsal III; incomplete; Left
Osmolska (1981) created the family Elmisauridae because of the similariteis between Chirostenotes and Elmisaurus. However Sues in 1997 in \\\" On Chirostenotes, a Late Cretaceous oviraptorosaur (Dinosauria: Theropoda) from western North America Journal of Vertebrate Paleontology, 1997, 17(4):698-716 \\\" described a previously unrecognized partial skeleton ROM 43250 of Chirostenotes pergracilis (Gilmore, 1924) from the Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada including parts of the skull, much of the pelvic girdle, and elements from all regions of the vertebral column.
According to Sues close structural correspondence between the maxilla of this specimen and the mandible of Caenagnathus collinsi R. M. Sternberg , 1940 indicates that the latter taxon should be considered a subjective junior synonym of Chirostenotes pergracilis and he also concluded that \\\'\\\'Ornithomimus\\\'\\\' elegans Parks, 1933 is probably also referable to Chirostenotes. He regarded the family-level taxon Elmisauridae Osmolska, 1981 as a subjective junior synonym of Caenagnathidae R. M. Sternberg, 1940.
Currie and Russell (1988) sorted the \\\"elmisaurid\\\" material then described from North America into two distinct morphs based on the morphology of the manus and pes: a \\\"robust\\\" morph (CMN 2367 [type of Chirostenotes pergracilis], CMN 8538 [type of Macrophalangia canadensis]) and a \\\"slender\\\" morph (ROM 781 [type of \\\'\\\'Ornithomimus\\\'\\\' elegans], RTMP 79.20.1) suggesting that the two morphs may represent the two sexes of a single dimorphic species and speculated that the mandibles named Caenagnathus collinsi and Caenagnathus sternbergi (which also differ in their relative slenderness) may also be referrable to these robust and slender morphs of Chirostenotes pergracilis, respectively.
Currie (1989, 1990) made ROM 781, an incomplete hindlimb, the holotype of his new combination, Elmisaurus elegans. ROM 781 was first described and named \\\'\\\'Ornithomimus\\\'\\\' elegans by Parks (1933). Russell (1972) had referred the material to Macrophalangia. Currie (1989) noted similarities between ROM 781 and theropod hindlimb bones from Mongolia named Elmisaurus rarus. These similarities included the degree of coossification of the tarsometatarsus (complete fusion of metatarsals II-IV with adjoing tarsals III and IV), a prominent proximolateral process on tarsal IV, and the proximal part of metatarsal III being triangular in section (not diamond-shaped, as in Chirostenotes pergracilis). Currie (1989) consequently removed ROM 781 from Chirostenotes pergracilis and made it the holotype of a second species of Elmisaurus, Elmisaurus elegans. Currie referred to this species two hitherto undescribed tarsometatarsi from Alberta which also showed this same pattern of coossification (RTMP 82.39.4, ROM 37163).
Sues did not include the degree of tarsometatarsal fusion as a defining character for Chirostenotes (and its included species), but instead employed much the same criteria that Currie and Russell (1988) had earlier used to distinguish two separate morphs of Chirostenotes pergracilis. In light of ROM 43250, Sues (1997) could confidently refer CMN 8776 to Chirostenotes pergracilis, thereby sinking Caenagnathus collinsi as a junior synonym of Chirostenotes pergracilis CMN 2367. Sues (1997) returned ROM 781 to the genus Chirostenotes as the holotype of a second species, Chirostenotes elegans. Sues also assumed that Chirostenotes elegans and Caenagnathus sternbergi (Cracraft, 1971) CMN 2690 represented the same species.
Chirostenotes elegans differs fromother species of Chirostenotes[=\\\"Caenagnathus\\\"] in having smaller adult size and articular with higher, more arched cranio-caudal ridge on articulating surface, medial glenoid that is relatively short anterocaudally (Cracraft, 1971), no wel developed chorda tympani foramen or slot (Varricchio, 2001) Chirostenotes pergracilis can be distinguished from Chirostenotes elegans by its more elongate and shallow dentary; a proportionately longer mandibular symphysis; and the presence of a median ridge on the dorsal edge of this symphysis. Chirostenotes pergracilis also appears to be a larger and (judging by the construction of the hand and foot bones) less gracile species than Chirostenotes elegans. (Sues, 1997)
Varricchio (2001) described a fragmentary lower jaw (MOR 1107), including the caudal end of the right mandibular ramus and referred the specimen to \\\"Caenagnathus sternbergi\\\" (=?Chirostenotes elegans) collected from the Upper Cretaceous (Campanian) Two Medicine Formation at Lanslide Butte, Clacier County, Montana.
Sources: Tim Williams pers comm.; Glut The Encyclopedia Sup. 3; Suez, (1997); The Dinosauria II; Mesozoic Vertbrate Lfie, (Tanke & CArpenter, (2001)