Historical Analysis of Theories of Chelonian Relationship

Abstract

Abstract.—The history of chelonian systematics reflects the underlying theme of biologic sys-tematics: the search for natural groups characterized by an inter-nesting pattern of features. Eighteenth century turtle systematics was dominated by the discovery of new species followed by the subdivision of Linnaeus ' single genus, Testudo, into many genera. Higher category clas-sifications were first based on habitat-related features; but as more morphologic information became available and was seen to be inconsistent with these classifications, new higher taxa (e.g., cryptodires and pleurodires) were recognized and tested successfully. The advent of pro-cess hypotheses in the form of evolutionism had a deleterious effect on turtle systematics due to the erection of supposedly ancestral and adaptational taxa. Phylogenetic systematics may be considered as the most recent phase in chelonian systematics but instead of being a new meth-odology, it is a more precise and objective technique of discovering and testing natural groups of the sort systematists have been seeking for centuries. A new classification and cladogram of turtles utilize these principles. [Classification; turtles; cladistics; history.] The most important contribution of comparative biology is the recognition that