Acta Palaeontologica Polonica

The classification and evolution of the Heterostraci

L. Beverly Tarlo

Acta Palaeontologica Polonica 07 (1-2), 1962: 249-290

An outline classification is given of the Heterostraci, with diagnoses of the following orders and suborders:  Astraspidiformes, Eriptychiiformes, Cyathaspidiformes (Cyathaspidida, Poraspidida, Ctenaspidida), Psammosteiformes (Tesseraspidida, Psarnmosteida), Traquairaspidiformes, Pteraspidiformes (Pteraspidida, Doryaspidida), Cardipeltiformes and Amphiaspidiformes (Amphiaspidida, Hibernaspidida, Eglonaspidida). It is shown that the various orders fall into four main evolutionary lineages - cyathaspid, psammosteid, pteraspid and amphiaspid, and these are traced from primitive tessellated forms. A tentative phylogeny is proposed and alternatives are discussed.

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