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==Conodonts==

==Conodonts==

Conodonts are extinct toothlike microfossils composed of calcium phosphate whose biological affinities, while poorly understood, lie with chordates. Conodonts are widely distributed in marine rocks of Cambrian through Triassic age. They are excellent indicators of time and thermal maturity—especially in carbonates, where other methods of evaluating organic thermal maturity are less successful. Conodonts are commonly used as zonal indices for the latest Cambrian through Triassic because they were abundant, evolved rapidly, and were widespread geographically.<ref name=ch17r83>Sweet, W., C., 1988, The Conodonta: morphology, taxonomy, paleoecology, and evolutionary history of a long-extinct animal phylum: Oxford [University Press] Monographs on Geology and Geophysics 10, 212 p.</ref> Although found in most marine rocks, conodonts are most efficiently recovered from the insoluble residues of carbonates dissolved in weak acids or from easily disaggregated shales.

Conodonts are extinct toothlike microfossils composed of calcium phosphate whose biological affinities, while poorly understood, lie with chordates. Conodonts are widely distributed in marine rocks of Cambrian through Triassic age. They are excellent indicators of time and thermal maturity—especially in carbonates, where other methods of evaluating organic thermal maturity are less successful. Conodonts are commonly used as zonal indices for the latest Cambrian through Triassic because they were abundant, evolved rapidly, and were widespread geographically.<ref name=ch17r83>Sweet, W., C., 1988, The Conodonta: morphology, taxonomy, paleoecology, and evolutionary history of a long-extinct animal phylum: Oxford [University Press] Monographs on Geology and Geophysics 10, 212 p.</ref> Although found in most marine rocks, conodonts are most efficiently recovered from the insoluble residues of carbonates dissolved in weak acids or from easily disaggregated shales.

Individual conodonts vary greatly in morphology, and taxonomy was originally based on the morphology of these individual specimens. While conodonts are common, the preserved remains of the soft-bodied animal that bore them are extremely rare. Based on a few preserved whole-animal specimens discovered recently (e.g., <ref name=ch17r40>Gabbott, S., E., Aldridge, R., J., Theron, J., N., 1995, A giant conodont with preserved muscle-tissue from the Upper Ordovician of South Africa: Nature, vol. 374, p. 800–803., 10., 1038/374800a0</ref> conodonts appear to have been located in the cephalic area and may have functioned as teeth.<ref name=ch17r71>Purnell, M. A., 1995, Microwear on conodont elements and macrophagy in the first vertebrates: Nature, vol. 374, p. 798–800., 10., 1038/374798a0</ref> However, the conodont animal apparently bore many conodonts of differing shapes and morphologies, based on the study of the very rare whole-animal specimens and rare bedding-plane groupings of conodonts representing individual animals. This recent information has led to more accurate multielement species concepts.

Individual conodonts vary greatly in morphology, and taxonomy was originally based on the morphology of these individual specimens. While conodonts are common, the preserved remains of the soft-bodied animal that bore them are extremely rare. Based on a few preserved whole-animal specimens discovered recently (e.g., <ref name=ch17r40>Gabbott, S., E., Aldridge, R., J., Theron, J., N., 1995, A giant conodont with preserved muscle-tissue from the Upper Ordovician of South Africa: Nature, vol. 374, p. 800–803., 10., 1038/374800a0</ref> conodonts appear to have been located in the cephalic area and may have functioned as teeth.<ref name=ch17r71>Purnell, M. A., 1995, Microwear on conodont elements and macrophagy in the first vertebrates: Nature, vol. 374, p. 798–800., 10., 1038/374798a0</ref> However, the conodont animal apparently bore many conodonts of differing shapes and morphologies, based on the study of the very rare whole-animal specimens and rare bedding-plane groupings of conodonts representing individual animals. This recent information has led to more accurate multielement species concepts.

[[:file:applied-paleontology_fig17-8.png|Figure 1]] shows some typical conodonts.

 

[[file:applied-paleontology_fig17-8.png|thumb|{{figure number|17-8}}See text for explanation.]]

==See also==

==See also==