The palaeobiology of late Cambrian protoconodonts, paraconodonts and euconodonts

Cochrane, Karen Dawn (2001). The palaeobiology of late Cambrian protoconodonts, paraconodonts and euconodonts. University of Birmingham. Ph.D.

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Abstract

Late Cambrian protoconodonts, paraconodonts and euconodonts from Laurentia and Baltoscandia have been investigated in terms of their apparatus composition and histology. Protoconodonts are considered to be members of the phylum Chaetognatha in accordance with the views of previous authors. The apparatus compositions of some primitive euconodonts are more complex than previously thought, with Eoconodontus notchpeakensis being assigned a septimembrate apparatus that has been described using nomenclature formerly applied to Panderodus. The histology of primitive and more derived euconodonts is homologous, with the exception that 'true' white matter is replaced by 'pseudo'-white matter in the enamel crown. Globular calcified cartilage and atubular dentine are present in the basal bodies of species from the Proconodontus complex. Similarities in apparatus composition and histology between primitive euconodonts suggest that they form a monophyletic group. Paraconodonts possess multielement apparatuses, and a suprageneric classification has been erected on the basis of new apparatus descriptions. Finally, a histological comparison of the inner core in the paraconodont Proonoeotodus and the basal body in several euconodont genera, leads to the conclusion that certain paraconodonts are related to euconodonts, and that the history of the vertebrate mineralised dermal skeleton can be extended into the Middle Cambrian.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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