Morphology,ontogeny, and heterochrony in lower and middle Cambrian Gogiids (Eocrinoidea,Echinodermata) from Guizhou Province,China |
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Authors: | Ronald Parsley |
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Institution: | 1.Department of Earth and Environmental Sciences,Tulane University,New Orleans,USA |
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Abstract: | Gogiid eocrinoids from the Lower Cambrian (Balang Formation — Guizhoueocrinus) and basal Middle Cambrian (Kaili Formation — Sinoeocrinus, Globoeocrinus) in Guizhou Province, China are found in great numbers and are extremely well preserved as high fidelity molds in shale/mud
sized siliciclastics. Because of their numbers, complete ontogenetic growth sequences have been observed. Significant differences
in growth patterns (heterochrony) are present between Lower and Middle Cambrian genera: thecal plates tend to be paedomorphic
in development, while the sutural pores developed between them are peramorphic in their development. Because of the large
surface area of theca and brachioles relative to the size of the attachment area, considerable drag in ambient currents would
necessitate a strong attachment medium. Anchoring by “biogluing”, possibly by collagen, directly to the substrate or to biodetritus
is proposed as the method of attachment. |
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