Using engineering technologies, Rivron and his team assembled them for the first time in such a way as to trigger self-organisation, resulting in the formation of what they called "blastoids
Faunas preserved and collected in this manner, here and elsewhere (for example, the Salem Limestone of southern Indiana [Beede 1906]), are commonly dominated by camerate crinoids and blastoids. This tendency may be controlled by either the ecology of the facies that supported organisms, which as fossils were susceptible to this type of preservation, crinoid taphonomy, or both.
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.
(** Denotes holotype, * specimen crushed.) 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.
Many fossilized blastoids and crinoids have platyceratid-snail fossils attached near their anus, a location that matches most of the drill holes.
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.
There are even examples in which this has been demonstrated (e.g., 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.