. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 186 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 18. H. tucki. A. Right pelvis, lateral view. B. Left femur, lateral view. Scale = 5 cm. The single most important feature of the acetabulum is the expanded articular surface at the posterodorsal corner. Here the ischiadic peduncle of the ilium flares out, creating an horizontal articular shelf and buttress against which the femoral head would have rested. The ventral surface of this shelf is a continuation of the acetabulum and would have borne articular c
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. 186 ANNALS OF THE SOUTH AFRICAN MUSEUM. Fig. 18. H. tucki. A. Right pelvis, lateral view. B. Left femur, lateral view. Scale = 5 cm. The single most important feature of the acetabulum is the expanded articular surface at the posterodorsal corner. Here the ischiadic peduncle of the ilium flares out, creating an horizontal articular shelf and buttress against which the femoral head would have rested. The ventral surface of this shelf is a continuation of the acetabulum and would have borne articular cartilage during life. The ilio-ischial suture lies below this buttress and is separate from it. Structurally, this articular buttress closely resembles the antitrochanter of birds (completely different from the 'antitrochanter' of dinosaurs). Very strong ligaments connect the iliac antitrochanter and the femoral greater trochanter in birds. This system resists the collapse of the body on the femur when the body is supported by only one leg. Unquestionably, the structural similarity to the avian acetabulum argues that some similar mechanical system in the pelvis and hind limb of H. tucki prevented excessive pelvic tilt when weight was borne by a single hind limb. The dorsal margin of the ilium is slightly convex; its arc is 101 mm while the chord (that is, maximum iliac length) is 96,7 mm. A ridge for muscle attachment runs from the tip of the anterior to the tip of the posterior process: beginning on the ventral flange of the anterior process, it passes obliquely upwards to the dorsal margin of the ilium, 20 mm behind the tip of the anterior process; the very last 15 mm of the ridge descends from the dorsal rim to the middle of the lateral surface of the posterior iliac process. In Romer's reconstruc- tion of the hind limb musculature of Thescelosaurus {\921a) this ridge marks the attachment of the ilio-tibialis and ilio-fibularis muscles. The ilio-tibialis 1. Please note that
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
