EXTENSIVE Echinoderm Death Assemblage

Description: This massive plate holds an extensive asmblage of echinoderms. There are no less than TEN ophiuroid starfish of the genus Stenaster. This is a most unusual brittlestar in that it is most asteroid-starfish-like in its exterior morphology. While it has a “typical” starfish shape with short, wide arms, it lacks the madreporite and ambulacral grooves of a true starfish. Stenaster is interpreted as an ophiuroid which has secondarily adopted a deposit-feeding mode of life, analogous to that of some extant asteroids, making it convergent on the true starfish (asteroids). The second echinoderm is a pair of juvenile Cupulocrinus seen crossed at the top of the matrix. There are numerous additional crinoid stems, a Brachiopod, and several pieces of coral to round out this excellent representation of the Middle Ordovician seafloor of Ontario.