RECOGNITION OF THE ASTEROID (ECHINODERMATA) CROWN GROUP: IMPLICATIONS OF THE VENTRAL SKELETON

From: Journal of Paleontology | Date: March 1, 2004| Author: | Copyright information

ABSTRACT-All known post-Paleozoic asteroids belong to the crown group, and no crown-group asteroid is known from lhe Paleo/.oic. A scanty fossil record provides limited data on morphology of both Paleozoic stem-group sister lineages and on the Triassic crown group diversification. Timing of events is weakly constrained. Interpretations based on this meager record are tentative. Within limitations of the record, recent work suggests that skeletal arrangement of the ventral surface offers apomorphies of crowngroup diversification. Enlarged disk size is common in the crown group. Large disks are ...

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