The Ornithomiimid Group

Matthew, W. D., & Brown, B., 1922, The family Deinodontidae, with notice of a new genus from the Cretaceous of Alberta., Bulletin of the American Museum of Natural History 56, pp. 365-385 : 373

3.— The Ornithomiimid Group of the Cretaceous

Coelosaurus , Ornithomimus , and Struthiomimus

It will hardly be open to question that these three genera form a closely allied natural group. Whether they should or should not be held distinct is at present a matter of opinion. The family may be characterized on the basis of the Struthiomimus skeleton described by Osborn as follows:

1.—Moderate size and slender proportions.

2.—Skull relatively small, toothless, orbital fenestra very large, jaw short and shallow.

3.—Quadrate closely sutured to quadratojugal, elongated, extending forward and • downward.

4.—Unknown.

5.—Cervicals very long and slender.

6.— Fore limb slender but much elongate throughout.

7.—Manus peculiarly specialized, me. I—III of equal length and thickness, me. I divergent at distal end, appressed medially to me. II, me. Ill parallel but not appressed, phalanges greatly elongate. Distal ends of metacarpals all with convex heads.

8.—Ungual phalanges of manus moderately compressed, elongate, not strongly curved.

9.—Pelvic bones united. Ilium without peduncle, elongate and decurved anteriorly, ischium long, slender, flattened and decurved, moderately expanded at tip.

10.—Tibia longer than femur, metatarsals long, phalanges of moderate proportions.

11.—Metatarsals II and IV long, slim, subequal, median metatarsal broader at distal end but the shaft greatly reduced in the distal portion, trigonal, the inferior sides closely appressed to the lateral metacarpal shafts, in the proximal portion reduced to little more than a thread, partly concealed between the lateral shafts; the head a little enlarged but enclosed dorsad and plantad by the much larger heads of the lateral metatarsals. The distal ends of the lateral metatarsals are convex both ways, that of the median plano-convex. Vestigial 1st and 5th metatarsals as in Megalosauridae , but further reduced or sometimes? absent.

12.—Phalanges of pes of moderate length, the unguals rather short and not strongly curved or compressed.

13.—Tail elongate, the distal caudals strongly interlocked by prolongation of the postzygapophyses.