Mongolian elmyi (foot) + Latin -saurus [Greek sauros (lizard or reptile)]. = "foot lizard."

Formation and Stratigraphy: the Dinosaur Park Formation and the Nemegt Formation (Upper Cretaceous).

Geography and Locality: (Nemegt F.) the Khulsan locality, Bayankhongor, Mongolia; (Dinosaur Park [Judith River] F.) southern Alberta, Canada.

Age: the middle Campanian to possibly the early Maastrichtian.

Elmisaurus was a medium-sized, robust (about 7 feet estimated is full grown; see Osmólska, 1981) with robust toes, and an unusual, fused tarsometatarsal structure of the epipodials reminiscent of birds, but unlike them in the lack of fusion between the metatarsal bones themselves. The genus Elmisaurus contains two species, and manual elements are known by only the type species (E. rarus) so manual description is reserved for that species. However, manual elements do not differ in any distinguished way between Elmisaurus rarus and Chirostenotes pergracilis, so the manual elements are not considered significant taxonomic characters except as apomorphies of the Caenagnathidae (see Currie and Russell, 1987; Currie, 1990; and Sues, 1997).

• Chirostenotes rarus Paul, 1988 (Osmólska, 1981)

Elmisaurus; Latin rarus (rare). = "rare foot lizard."

Formation and Stratigraphy: the Nemegt Formation (Upper Cretaceous).

Geography and Locality: the Khulsan locality, Bayankhongor, Mongolia.

Age: the late Campanian to possibly the early Maastrichtian.

Holotype:
• ZPAL MgD-I/172: nearly complete left tarsometatarsus (metatarsals fused to distal tarsals 1-3), lacking mt I.

  Refered specimens:

• ZPAL MgD-I/20: proximal portion of right tarsometatarsus (metatarsals fused to distal tarsals 1-3), lacking all but tip of mt III.
• ZPAL MgD-I/98: partial pes, distal ends of right metatarsals II-IV, pedal digits 1 (I-1), 2 (II--1-3), 3 (III--1-3), 4 (IV--4), and partial manus, mc 1, all but proximal portion of mc 2, and distal half of mc 3, manual digits 1 (I--1-2), 2 (II--102), and 3 (III--1-2).

Along with the generic description, E. rarus includes a manus with some robust metacarpals, as does Chirostenotes pergracilis (see Currie and Russell, 1987; Currie, 1990; Sues, 1997), but is interesting in having a third digit that appears to be especially slender, when compared with C. pergracilis, but this does not appear to offer any relative weakness in the bones, as the phalanges are laterally compressed, and flexion of the manus would act on the narrow, deep edge and not exert forces on the broader, shallower lateral sides, so strength is relatively increased. This may have offered E. rarus a relatively stronger grasping hand than is known in other oviraptorosaurs, including Chirostenotes (Osmólska, 1971; Barsbold, Osmólska, and Maryanska, 1990; Currie and Russell, 1987; Currie, 1990; and Sues, 1997).

E. rarus differs from the second Elmisaurus species, E. elegans, by the relative more completeness of the tarsal fusion, and the prescence of a posterior ridge on the proximal surface of the tarsal cap (Currie, 1988), as well as being larger comparatively, with greater girth of the metatarsus and in being shorter relative to width.

• Chirostenotes elegans Sues, 1997 (Parks, 1933)
• Ornithomimus elegans Parks, 1933

Elmisaurus; Latin elegans (elegant or refined). = "elegant foot lizard."

Formation and Stratigraphy: the Dinosaur Park Formation (Upper Cretaceous).

Geography and Locality: southern Alberta, Canada.

Age: the middle Campanian to possibly the early Maastrichtian.

Holotype:
• ROM 781: a partial tarsometatarsus.

  Refered specimens:

• RTMP 82.39.4: a metatarsal.
• ROM 37163: a metatarsal.

More slender than E. rarus, E. elegans has no true metatarsus, the distal tarsals fused together, but not to the metatarsus, forming a tarsal "cap," and lacks the posterior proximal ridge present in E. rarus (Osmólska, 1981), making this animal more superficially similar to Chirostenotes, to which Sues (1997) referred it, making the species Chirostenotes sternbergi a junior synonym of "Chirostenotes" elegans (see Currie, 1988; Sues, 1997). I reserve E. elegans in Elmisaurus based on the multitude of Elmisaurus features, contra Sues (1997), considering that the tarsal cap and posteromedial tongue of the tarsus are key features of Elmisaurus, lacking in all specimens of Chirostenotes having pedal material that have been published (see Currie and Russell, 1987; Currie, 1988; Sues, 1997).

E. elegans (or rather, ROM 781) has the distinction of being refered to three different taxa: Ornithomimus elegans Parks, 1933; Chirostenotes elegans Sues, 1997; and Elmisaurus elegans Currie, 1988. E. elegans can be distinguished from E. rarus on the based of its more slender metatarsus, lack of a tarsometatarsus (in known specimens), and lack of a proximal posterior ridge on the fused tarsus; it has the most slender foot of the oviraptorosaurs, including Conchoraptor and Chirostenotes (see Barsbold et al., 1990; and Currie, 1990), and would probably have had longer or more slender limbs than E. elegans, but future discoveries will settle the phylogenetic and morphological questions surrounding this taxon.

Discussion:

The appearance of Elmisaurus is an enigma, given the paucity of material adequate to forming even a vague impression of its appearance. It would have been similar to Chirostenotes, given morphology of the manus and pes, but other than that, there is no way of knowing what it would have looked like. The lack of such information has left me to make this the one oviraptorosaur taxon that doesn't have some sort of drawing of its life restoration, unless (and I'm not) I would be prone to draw its hands and feet alone. Such a restoration offers me no clue to its identity.

Phylogenetically, Elmisaurus pairs with Chirostenotes consistently in simple binary cladistic tables, with the non-cranial caenagnathid characters can be chosen as apomorphies of the taxon (Caenagnathidae == { Elmisaurus + Chirostenotes } although Sereno (1999) has defined it thus: Caenagnathidae == { Chirostenotes > Oviraptor }; I use the Buchholz--Wagner Phylogenetic Notation System, a complete run down of which can be found at T. Michael Keesey's website (see below)). This makes it most likely that Elmisaurus the closest relative of Chirostenotes, which has not been contested (Currie, 1990).

• Barsbold R.; Maryanska, T.; and Osmolska, H. 1990. Oviraptorosauria. p. 249-258. (in Weishampel, D.A.; Dodson, P.; and Osmolska, H. (eds.) The Dinosauria [University of California Press, Berkeley (Los Angeles, Oxford)]).
• Currie, P.J. 1989. The first records of Elmisaurus (Saurischia, Theropoda) from North America. Canadian Journal of Earth Sciences 26: 1319-1324.
• Currie, P.J. 1990. Elmisauridae. p. 245-248 (in Weishampel, D.A.; Dodson, P.; and Osmolska, H. (eds.) The Dinosauria) University of California Press, Berkeley [Los Angeles, Oxford].
• Currie, P.J. and Russell, D.A. 1988. Osteology and relationships of Chirostenotes pergracilis (Saurischia, Theropoda) from the Judith River (Oldman) Formation of Alberta, Canada. Canadian Journal of Earth Sciences 25: 972-986.
• Osmólska, H. 1981. Coossified tarsometatarsi in theropod dinosaurs and their bearing on the problem of bird origins. Palaeontologia Polonica 42: 79-95.
• Parks, W.A. 1933. New species of dinosaurs and turtles from the Belly River Formation of Alberta. University of Toronto Studies (Geological Series) 34: 1-33.
• Paul, G.S. 1988b. Predatory Dinosaurs of the World: a Complete Illustrated Guide. [Simon & Schuster, New York]. pp. 464.
• Sues, H.-D. 1997. On Chirostenotes, a Late Cretaceous oviraptorosaur (Dinosauria: Theropod) from western North America. Journal of Vertebrate Paleontology 17: 698-716.
• Weishampel, D.B.; Dodson, P.; and Osmólska, H. 1990. The Dinosauria. [University of California Press; Berkeley, Los Angeles, London]. pp. 733.

  Web Links:

• Keesey, T.M., 1999. The Dinosauricon ... Click Here.

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