Biomechanics of Animal Movement

Study Notes

Biomechanics of Animal Movement

Biomechanics is the study of animal movement, often called "the mechanics of life."
It examines how animals navigate and adapt to their environment.

Biomechanics of Extinct Animals

Examining extinct animals provides insights into forms not currently observed.
This aids in understanding the limitations of these extinct animals.
Functional adaptations, such as terrestrial movement and flight, are studied.
Examples include Quetzalcoatlus (pterosaur) and Patagotitan (sauropod).

Skeletal Adaptations to Size

Small animals do not scale proportionally with larger animals.
Small animals have thinner bones and crouched postures.
Large animals have thicker, more robust bones and a straighter, column-like posture.
Examples include the wood mouse and elephant.

Posture

Sprawling posture was the ancestral form for tetrapods.
Erect posture, seen in dinosaurs and mammals, necessitates special adaptations.
An open hip socket in dinosaurs supported an erect posture.
Examples include early tetrapod trackways and Seymouria, an early tetrapod.

Quadrupedalism

Movement using all four limbs is ancestral for most tetrapods, promoting stability.
Movement involves rotation of the chest and hips.

Bipedalism

Walking on two hind limbs.
Obligate bipedalism is seen in birds and humans, typically exhibiting erect postures.
Bipedalism was ancestral to dinosaurs, enabling flight and increased manual dexterity in humans.
Partial or occasional bipedalism is observed in other mammals.
Examples include ostriches and dinosaurs like Tyrannosaurus.

Bipedalism—Further Innovations

Bipedalism facilitated flight (birds) and increased manual dexterity and tool use (humans).

Bipedalism—Other Forms

Occasional bipedalism is seen in some mammals and reptiles.
Kangaroos use a tripodal stance, employing three limbs for support.

Postural Enigma

Spinosaurus (Late Cretaceous theropod), inhabiting Egypt and Morocco, presents a postural challenge.
Its wrists cannot pronate (rotate inwards) for hand support, unlike other theropods.
Fossils of Spinosaurus hands and forearms are missing.

Speed Measurement

Running speeds are measured from live animals.
Stride length is analyzed using statistical tools.
Dr. Robert McNeill Alexander, a biomechanist, determined relationships between speed, stride length, and body size in dinosaurs.

Alexander's Dinosaur Speed Calculator

Predictions of running speeds were made using stride length and body size.
These methods used empirical observations of modern animals, applied to dinosaur fossils.

Speed—Dinosaurs

Smaller dinosaurs could reach speeds >35 km/hr.
Large dinosaurs like Tyrannosaurus were slower.

Description

Explore the fascinating field of biomechanics as it applies to animal movement, including extinct species. Understand how skeletal adaptations relate to size and the evolution of posture in various animals. This quiz covers everything from modern adaptations to the mechanics involved in the movement of ancient organisms.