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

CHAPTER 3: Tensile keystone model of fundional arthrology in the
tyrannosaurid arctometatarsus
As noted in the Introduction to this thesis, integrative studies of the
musculoskeletal system provide a promising approach for revealing locomotor
dynamics in extinct vertebrates. The immediately preceding section (Chapter 2)
describes the osteological characteristics of the tyrannosaurid arctometatarsus.
Osteology alone is of limited utility in interpreting biomechanis when considered
in isolation from muscles, tendons, and ligaments (Alexander 1977, Maloiy et
al. 1979). The curent chapter explores hypothesized interactions between
tyrannosaurid metatarsals and the ligaments that bound them together.
A number of studies have explicated the locomotor role of foot ligaments and
tendons and their interactions with associated bones. Elastic fore and hind foot
connective elements store, retum, and distribute fwtfall energies and forces; the
plantar aponeurosis and intennetatarsal ligaments of humans (Kerr et al. 1987;
Alexander 1988) and intercarpal ligaments of horses (Rubeli 1925) are
noteworthy examples.
A shock-absorbing function of ligaments obtains under specific physical
conditions. Ligaments paradoxically display greater strength and resiliency when
subject to high magnitude, sudden loadings, such as those inwrred during rapid
locomotion (Frank and Shrive 1994). In animals of large body size the
extensibility of ligaments increases, because their cross sectional area is Iower
relative to mass than ligaments of smalier animals (Pollock 1991). The ligaments
of large animals store and retum more elastic strain energy, which increases