Phylogeny of calceocrinid crinoids (Paleozoic: Echinodermata): Biogeography and mosaic evolution

Abstract

A structured evolutionary pattern emerges from cladistic and stratocladistic analyses of the Calceocrinidae (Echinodermata). These Paleozoic disparid crinoids were dominated by three long-ranging genera, and other genera were derived during endemic radiations in North America and in Europe. Calceocrinid evolution was highly mosaic, including the repetition of morphological transitions, numerous character reversals, and evolutionary independence of characters. As a family, the calceocrinids make up a highly derived, unique family because the crown is bilaterally symmetrical, is reflexed onto the stem by a hinge between the radial and basal circlets, and was normally situated just above the substratum. The analysis included 23 genera with 17 characters; three were coded as ordered based on previously observed evolutionary trends. Standard cladistic analysis yielded a total of 17,000 equally parsimonious trees. The addition of stratigraphic data through the use of stratocladistic methodology reduced this number to 16 equally parsimonious trees.