Blastoids commonly are taphonomically similar to camerate crinoids (Meyer and others 1989; Ausich 2001).
Only two blastoid species and six crinoid species have been described from the Columbus Limestone of central Ohio (Table 1), and no identified echinoderms have been described previously from the Delaware Limestone.
TABLE 1 Blastoid and Crinoid fauna of the Columbus Limestone.
Some of the holes drilled in fossils of the marine echinoderms called blastoids and crinoids seem to have been made by parasites, not predators, says Tomasz K.
Blastoids and crinoids are related to modern starfish and sea urchins.
Other researchers have found multiple holes, as well as some incomplete and healed holes, in specimens of other blastoids.
The writer's collection includes well-preserved solitary and colonial corals, crinoid columns and calices, bryozoans, and blastoids
, including a rare Diploblastus wholly or partially replaced by fluorite.
On the other hand, certain subgroups - trilobites and blastoids - showed the opposite pattern (Foote 1993).
For hierarchical development, trends in variability are consistent with increasing depth of developmental interactions (although other explanations cannot be ruled out) in arthropods and blastozoans, but not in trilobites and blastoids.
early Paleozoic eocrinoids, a group of echinoderms from which ultimately descended blastoids, rhombiferans, and some other taxa) (Smith 1994).
After extensive phylogenetic study involving careful character analysis, he found that the Permian survivors among blastoid echinoderms were drawn from many branches of the evolutionary tree.
Stratocladistic reconstruction of blastoid evolutionary history.