Paleoecological and sedimentological significance of bioturbated crinoid calyces

Rapid burial of crinoids commonly is responsible for spectacular preservation of articulated specimens. However, some Paleozoic crinoids, especially large-calyx (≈camerate) crinoids, were scavenged after rapid, intact burial. Crinoids that were catastrophically buried and subsequently scavenged can be recognized in the fossil record by presence of (1) bioturbational texture, (2) abundant articulated stems, arms, and pinnules, (3) disarticulated calyx plates, and (4) articulated arms and pinnules oriented in hydrodynamically unstable positions. Large-calyx crinoids may have been selected by scavenging organisms preferentially because the large calyces housed gonads, which generally are the most nutritious parts of echinoderms.