. Bulletins of American paleontology. Middle Ordovician Crinoids: Brower & Veinus 403 are commonly thick shelled forms in which the buried region of the shell is greatly thickened for increased stability (Rudwick, 1970, pp. 91-94). This feature is conspicuously absent in C. dicyclicus (Sarde- son). For these reasons, the Twin Cities carabocrinid is thought to be a substrate dweller rather than a partially-buried species. Both possibilities are shown in Text-figure 3. The carabocrinids lived in an environment that was highly agi- tated periodically. Some crowns may have been detached from t
. Bulletins of American paleontology. Middle Ordovician Crinoids: Brower & Veinus 403 are commonly thick shelled forms in which the buried region of the shell is greatly thickened for increased stability (Rudwick, 1970, pp. 91-94). This feature is conspicuously absent in C. dicyclicus (Sarde- son). For these reasons, the Twin Cities carabocrinid is thought to be a substrate dweller rather than a partially-buried species. Both possibilities are shown in Text-figure 3. The carabocrinids lived in an environment that was highly agi- tated periodically. Some crowns may have been detached from their holdfasts by either or both wave and current action. This leads to. Text-figure 3. — Restorations of Twin Cities carabocrinids. The specimen in the foreground shows the most probable mode of life with the holdfast cemented directly to the seafloor. A less likely orientation with the holdfast and part of the dorsal cup buried in the sediment is sketched in the background. The crown is mainly reconstructed from NMNH 43008, which has a height of about 10 cm. The holdfast and stem are Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
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