Morphological changes in pedal phalanges through ornithopod dinosaur evolution: A biomechanical approach

Moreno, Karen; Carrano, Matthew T.; Snyder, Rebecca

Abstract

The evolution of ornithopod dinosaurs provides a well-documented example of the transition from digitigrady to subunguligrady. During this transition, the ornithopod pes was drastically altered from the plesiomorphic dinosaurian morphology (four digits, claw-shaped unguals, strongly concavo-convex joints, phalanges longer than wide, excavated collateral ligament fossae, presence of sagittal ridge, and prominent processes for the attachment of tendons) to a more derived condition (tridactyly, modification of the unguals into hooves, phalanges wider and thinner than long, lack of collateral ligament fossae, loss of sagittal ridge and tendon attachment processes, relatively flattened articular surfaces). These changes are particularly noteworthy given the overall conservatism in pedal morphology seen across Dinosauria. But what are the ftinctional consequences of these specific morphological transitions? To study them, we examine a wide range of pedal morphologies in four non-avian dinosaurs and two birds. Our analyses of the external morphology, two-dimensional models (using Finite Element Analysis), and internal bone structure demonstrate that this evolutionary shift was accompanied by a loss of digit mobility and flexibility. In addition, pedal posture was modified to better align the pes with the main direction of the ground reaction force, thus becoming well suited to support high loads. These conclusions can be applied to other, parallel evolutionary changes (in both dinosaurs and mammals) that involved similar transitions to a subunguligrade posture.

Más información

Título según WOS: ID WOS:000243272100005 Not found in local WOS DB
Título de la Revista: JOURNAL OF MORPHOLOGY
Volumen: 268
Número: 1
Editorial: Wiley
Fecha de publicación: 2007
Página de inicio: 50
Página final: 63
DOI:

10.1002/jmor.10498

Notas: ISI