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Description
The programme looks first at some examples of convergent evolution and secondly examines why different animals have different skeletal structures.
Metadata describing this Open University video programme
Module code and title: S101, Science: a foundation course
Item code: S101; 18
First transmission date: 10-07-1979
Published: 1979
Rights Statement:
Restrictions on use:
Duration: 00:24:00
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Producer: Denis Gartside
Contributors: R. McNeill Alexander; Neil Chalmers; John E. B. Currey
Publisher: BBC Open University
Keyword(s): Convergent evolution
Subject terms: Skeleton
Footage description: Film shots of bats in flight, of a bat giving birth to live young, of pigeons flying, of penguins swimming and hatching their eggs, of seals swimming and giving birth to live young, and of fish in a tank. Commentary by Chalmers - introduces the programme with a brief outline of what is meant by convergent evolution. Neil Chalmers looks in more detail at specific examples of convergent evolution; the forelimbs of several flying animals. Shots of skeletons of a human hand, of a bat wing, and of a pigeon wing. Also shots of the skeletal breast modifications in these two flying animals. Chalmers goes on to look at examples of convergent evolution in the forelimbs of aquatic animals. Shots of penguins, sealions, fish, and of their skeletons. Finally, Chalmers briefly looks at examples of divergence in quadrupedal land mammals. Shots of water buffalo, of hyena, of zebra, of an elephant, of a cheetah, and of a lion. He explains the purpose of the skeleton in these animals. Chalmers, with the aid of a piece of rubber, briefly explains what is meant by the terms 'stress' and 'strain' when referring to the forces acting on animal bones. McNeill Alexander, at the Dept. of Zoology, Leeds University, demonstrates some of the equipment with which he measures the forces acting on animal feet so that he can calculate the stresses in their leg bones. He demonstrates the apparatus. Then, with the aid of a canine leg bone to illustrate his points, he explains how he goes about calculating the stresses on the leg bones. Chalmers examines a skeleton of Tyranosaurus Rex and points out that enormous forces must have been acting on the legs of this animal. In order to study the stresses which develop in bones before the bone breaks, John Currey examines a piece of plastic in a tensile testing machine under polarised light. He then tests a piece of simulated plastic bone to destruction. Neil Chalmers and John Currey explain how various land mammals from tiny antelopes to elephants adapt their skeletons to cope with the large forces placed on them. Shots of chevrotain, antelope and elephant skeletons. Also shots of plastic 'bones' of different shapes being tensile tested under polarised light. Finally, shots of an antelope and an elephant humerus.
Master spool number: 6HT/72910
Production number: FOUS018T
Videofinder number: 1193
Available to public: no