THE UNIVERSITY OF CALGARY Eric Snively A ... - Ohio University

tyrannosaurids (Figure 3.5), but are not present at this locations in Allosaurus
(Figure 3.9). A faceted distal MT III-MT IV articulation occurs in tyrannosaurids
(Figures 3.ô-3.8), but is entirely absent in Allosaurus, in whid'i MT IV shows
pronounced lateral angulation (Figure 3.9).
Figures 3.6-3.9 display the shape of al1 identified scars, in reconstructions of
the initial tracings. Proximal scars are subtriangular in al1 assessed theropods,
but in Allosaurus are long proximodistally relative to the length of the metatarsus.
In al1 three tyrannosaurids, distal articulations are long and taper proximally. The
average areas of adjacent distal scars are quite extensive in the tyrannosaurids
(Table 3.2). The average distal scar area exceeds the average proximal area by
1.5728 in the Daspletosaunrs specimen (MOR 590), 1.4029 in Alberfosaurus
(MOR 657), and by a factor of 1.4666 in the Tyrannosaurus metatarsus (MOR
555). Table 3.2 presents individual and average areas of intermetatarsal soft
tissue correlates in ail speurnens.
DISCUSSION
lmplicatîons of articulation anatomy
The results indicate correlates of soft tissues present on large theropod
metatarsals. However, the hypothesis that these are ligament attachment sites
must first be tested. Apparent ligament sites must be differentiated from tendon
attachments through phylogenetic inference (Bryant and Russell 1992, Bryant
and Seymour 1990, Wtmer 1995) and mechanical considerations. The
metatarsus is fusd in modem theropods (Gauthier 19861, which obviates extant