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
3 - Problems in understanding metatherian evolution
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
… present writer has pointed out the probability that the aplacental condition of most Marsupials is actually primitive, and that the placental connection in Perameles, like a multitude of other characters in which Marsupials resemble Placentals, has been independently acquired; in other words, that it represents a convergent or homoplastic development.
However this may be, we have the more definite fact that the marsupials and Placentals are collateral and, in a certain sense, equivalent groups of common parentage; and this conception may be welcomed as clearing the way for a better perception of the details of their secondary evolution or adaptive radiation.
Bensley (1903, p. 85)Importance of determining the order of appearance of diagnostic characters. – The relative age of different characters should in all cases be a primary object of research. The historical method (although open to many pitfalls) when judiciously applied seems more likely to lead to lasting phylogenetic results than the time honored method of setting down resemblances and differences between two animals…”.
Gregory (1910, p. 112)The simple well corroborated theme in this section that underlies the scrutiny of a few areas of marsupial biology is that answers without history are very incomplete. Yet, this history cannot be deciphered without considerable input from a most current understanding of causality (proximal as opposed to more distal) of sundry biological processes and mechanisms.
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- Publisher: Cambridge University PressPrint publication year: 1995