Book contents
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Phylogenetics of characters and groups, and the classification of taxa
- 3 Problems in understanding metatherian evolution
- 4 Form–function, and ecological and behavioral morphology in Metatheria
- 5 Background to the analysis of metatherian cruropedal evidence
- 6 Mesozoic and Cenozoic: Fossil tarsals of ameridelphians unassociated with teeth
- 7 Cruropedal attributes of living and fossil families of metatherians
- 8 Taxa and phylogeny of Metatheria
- 9 Paleobiogeography and metatherian evolution
- References
- Index
4 - Form–function, and ecological and behavioral morphology in Metatheria
Published online by Cambridge University Press: 16 October 2009
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Phylogenetics of characters and groups, and the classification of taxa
- 3 Problems in understanding metatherian evolution
- 4 Form–function, and ecological and behavioral morphology in Metatheria
- 5 Background to the analysis of metatherian cruropedal evidence
- 6 Mesozoic and Cenozoic: Fossil tarsals of ameridelphians unassociated with teeth
- 7 Cruropedal attributes of living and fossil families of metatherians
- 8 Taxa and phylogeny of Metatheria
- 9 Paleobiogeography and metatherian evolution
- References
- Index
Summary
It may be said that natural selection is daily and hourly scrutinising, throughout the world, every variation even the slightest; rejecting that which is bad, preserving and adding up all that is good; silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life. We see nothing of these slow changes in progress, until the hand of time has marked the long lapse of ages, and then so imperfect is our view into long past geological ages, that we only see that the forms of life are now different from what they formerly were.
Darwin (1859, p. 84)Morphologists have been slow in realizing that the basic principles of Darwin's theory of evolution by natural selection meant that understanding the evolution of anatomical features must be based on an analysis of how these structures interact with demands of the external environment on the organisms.
Bock (1990, p. 254)Some assumptions
Mammalian skeletal elements and coadapted areas within the body reflect the loading of the bones, the mechanics of locomotion, and habitual postures to varying degrees. The hand and foot are in particularly close physical contact with the details of the surface of the substrate. On the microscopic or tissue level the arrangement of different types of osteons in the Haversian system or the trabecular patterns further mirror the specific epigenetic responses of the tissue to stresses in addition to inherited patterns of bone form.
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- Publisher: Cambridge University PressPrint publication year: 1995