Pronunciation: droh-MISS-ee-oh-MY-muss
Meaning: Emu mimic
Author/s: Russell (1972)
Synonyms: Struthiomimus brevitertius (Parks, 1926)
First Discovery: Alberta, Canada
Acta Ordinal: #228
Dromiceiomimus brevitertius
Discovered in 1924 and described by William Parks in 1926, this lightly built ornithomimid began its scientific life under a different name: Struthiomimus brevitertius, and sat for decades in collections as just another "ostrich-mimic" dinosaur, its long legs and slender arms noted but not yet appreciated. That changed in 1972, when Dale Russell performed an extensive review of North American ornithomimids, paying particular attention to their limb proportions, and presumed that Struthiomimus proper—with more robust arms and proportionately shorter legs compared to its back—was built less for running and more for digging. Given those differences, Struthiomimus brevitertius was renamed
Dromiceiomimus—the "emu mimic"—and it also snaffled the remains that were previously known as Struthiomimus ingens.
In 1981, however, Anthony P. became the third Russell to stick his thumb into the Albertan ornithomimid pie, questioning whether arm build and leg length were enough to separate genera, and by the early 2000s, Dromiceiomimus was being folded into Ornithomimus edmontonicus. Yet renewed analysis in 2018, focusing on exceptionally long hindlimbs and distinctive thigh–shin-ratios of a referred specimen that became the first dinosaur to be removed from the field by helicopter in 1967, revived the possibility that Dromiceiomimus truly represents a separate, fleet-footed lineage. Right now, the for and against crowd are roughly 50/50.
In 1981, however, Anthony P. became the third Russell to stick his thumb into the Albertan ornithomimid pie, questioning whether arm build and leg length were enough to separate genera, and by the early 2000s, Dromiceiomimus was being folded into Ornithomimus edmontonicus. Yet renewed analysis in 2018, focusing on exceptionally long hindlimbs and distinctive thigh–shin-ratios of a referred specimen that became the first dinosaur to be removed from the field by helicopter in 1967, revived the possibility that Dromiceiomimus truly represents a separate, fleet-footed lineage. Right now, the for and against crowd are roughly 50/50.
(Emu Mimic with short third metatarsals)Etymology
Dromiceiomimus is derived from "dromiceius" (the old spelling of the genus name of the Emu) and the Greek "mimos" (mimic). The species epithet, brevitertius, is derived from the Latin "brevis" (short) and "tertius" (third), likely referring to its "short" third metatarsal. Parks noted that the second and fourth metatarsals were "closely apposed" where they meet the ankle, with no recess between them for a "missing bone", and therefore interpreted the third metatarsal as genuinely reduced in length. In reality, he was describing the arctometatarsalian condition decades before the term existed, whereby the third metatarsal is "pinched" between its neighbours into a tapering wedge that disappears from view at the front-top end, and is thought to be an adaptation for swift running. Probably.
Discovery
The first remains of Dromiceiomimus were discovered in the Horsethief Member of the Horseshoe Canyon Formation, 38 m above the east bank of the Red Deer River, Alberta, Canada, by G. Lindblad in 1924. In 1926, Parks listed the discovery site as in the "Edmonston Formation", but that was before the Edmonton was elevated to group status and divided into four formations; the Horseshoe Canyon, Whitemud, Battle and Scollard.
The holotype (ROM 797) is a partial skeleton consisting of hip and back vertebrae, part of the tail, pelvic bones, and both legs.
Referred material:
AMNH 5201.
Both upper arm bones, pelvic bones, left thigh bone, both lower legs, and parts of the foot.
Found 9 m above the west bank of the Red Deer River. NMC 12068.
Hip and back vertebrae, most of the tail, pelvic bones, and both hind legs.
Found 55 m above the east bank of the Red Deer River. NMC 12069.
A partial tail, pelvic bones, a left thigh, both lower legs, and both feet.
Found at the same site as NMC 12068. NMC 12070.
Lower ends of both lower legs, metatarsals, and several toe bones.
Found at the same site as NMC 12068. NMC 12228.
A partial skull and lower jaws, much of the backbone, a nearly complete tail, pelvic bones, left thigh and lower leg, left metatarsals, and two toe bones.
Found 44 m above the west bank of the Red Deer River. ROM 852 (type of "Struthiomimus ingens").
Hip and back vertebrae, pelvic bones, a complete left hind leg, a right thigh and most of a right lower leg.
Found 61 m above the east bank of the Red Deer River. UALVP 16182.
A partial skeleton, discovered in what is now known as TMP locality #L2205 in the Tolman Member of the Horseshoe Canyon Formation, Dry Island Buffalo Jump Provincial Park, east of Huxley, Alberta, Canada, by Bob Graham of Stettler, Alberta, in 1966. UALVP 16182 was excavated by a team led by Dr. Richard Fox in 1967, and is historically noteworthy for being the first dinosaur specimen ever extracted from the field using a helicopter.
