Dinosaurs: A Very Short Introduction by David Norman

Author:David Norman
Language: eng
Format: epub, pdf
Publisher: Oxford University Press, USA

The cladogram that results from this type of analysis represents no more than a working hypothesis of the relationships of the animals that are being investigated. Each of the branches on the tree mark points at which it is possible to define a group of species that are all connected by their sharing a number of characteristic features. And using this information it is possible to construct what is, in effect, a sort of genealogy or phylogeny representing a model of the evolutionary history of the group as a whole. For example, if the known geological times of occurrence of each of the species are plotted on to this pattern, it becomes possible to indicate the overall history of the group, and also the probable time at which various of the species may have originated. In this way, the cladogram, rather than simply representing a convenient spatial arrangement of species, begins to resemble a real genealogy. Obviously, each such phylogeny created in this way is only as good as the data available, and the data and how it is scored can change with the discovery of new, better, or more complete fossils, and also as new methods of analysis are developed or older ones are improved upon.

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