Citipes

Skeletal reconstructions of Dinosaur Park Formation caenagnathids. Skeletal reconstructions of Citipes elegans (left), Chirostenotes pergracilis (middle), and Caenagnathus collinsi (right), showing variation in skeletal representation and body size. Previously referred material is indicated in white and newly referred material is indicated in red for each taxon. Blue asterisks indicate elements that have been histologically sampled for each taxon. Citipes elegans: dentaries, metatarsal IV; Chirostenotes pergracilis: dentaries, tibia; Caenagnathus collinsi: pubis.

Skeletal reconstruction of Citipes elegans. Previously referred material is indicated in white and newly referred material is indicated in red.

Life restoration of Citipes elegans.

UALVP 59606, metatarsal IV of Citipes elegans. Left metatarsal IV and fused distal tarsal IV of UALVP 59606 in anterior (A), lateral (B), posterior (C), medial (D), proximal (E) and distal (F) views. Red line indicates plane of section in Figure 15. Abbreviations: cond, condyle; dt IV, distal tarsal IV; lclf, lateral collateral ligament fossa; lp, lateral process; mclf, medial collateral ligament fossa; mt II, contact for metatarsal II; mt III, contact for metatarsal III; mt V, contact for metatarsal V; mt IV, metatarsal IV; m.tc, attachment for m. tibialis cranialis; pdp, proximodorsal process; plr, posterolateral ridge; pprt, posterior protuberance.

Osteohistology of UALVP 59606, metatarsal IV of Citipes elegans. Overview of histological thin section of UALVP 59606 in plane-polarized (A) and cross-polarized (B) light, showing locations of close-up images. Detail (C) of cortex showing predominantly primary fibrolamellar bone with longitudinal-reticular vascularity, endosteal layer, and cyclical growth marks (arrows), under plane-polarized light. Close-up (D) of well developed endosteal layer on the medullary cavity, showing sec- ondary excavation by simple vascular canals, under cross-polarized light. Close-up (E) of tightly packed cyclical growth marks (arrows) near the periosteal surface of the cortex, under plane-polarized light. Close-up (F) of periosteal surface of cortex, showing avascular parallel-fibered bone indicating an incipient external fundamental system (double ended arrow) with three LAGs (arrows). Abbreviations: efs, incipient external fundamental system; el, endosteal lamellae; hb, Haversian bone; pfb, parallel-fibered bone; radv, radial simple vascular canal; so, secondary osteon.

Tarsometatarsi of caenagnathids from the Upper Campanian Dinosaur Park Formation, Dinosaur Provincial Park, Alberta, Canada. A. TMP 1993.036.0181 (Chirostenotes pergracilis). B. TMP 1982.016.0006 (Citipes elegans). C. ROM 781 (Citipes elegans holotype). D. TMP 1996.012.0141 (Citipes elegans). Tarsometatarsi in proximal (A1–D1), anterior (A2–D2), and posterior (A3–D3) views.

Skeletal reconstructions of Dinosaur Park Formation caenagnathids. Skeletal reconstructions of Citipes elegans (left), Chirostenotes pergracilis (middle), and Caenagnathus collinsi (right), showing variation in skeletal representation and body size. Previously referred material is indicated in white and newly referred material is indicated in red for each taxon. Blue asterisks indicate elements that have been histologically sampled for each taxon. Citipes elegans: dentaries, metatarsal IV; Chirostenotes pergracilis: dentaries, tibia; Caenagnathus collinsi: pubis.

Skeletal reconstruction of Citipes elegans. Previously referred material is indicated in white and newly referred material is indicated in red.