What is Mitrocrinus wetherbyi S. A. Miller and Gurley, 1894?

Abstract

Phylogenetic classification is dependent upon confident ordering of character states that can be greatly facilitated if the earliest members of a clade are known and well understood. Unfortunately, one of the oldest known representatives of the camerate crinoid order Monobathrida is the problematic Mitrocrinus wetherbyi S. A. Miller and Gurley, 1894. It is problematic because it is a teratologic specimen with hexamerous symmetry and because its basic constructional design is more typical of middle to late Paleozoic monobathrids than of a Middle Ordovician monobathrid. A more advanced-looking construction does not preclude this crinoid from being the most primitive monobathrid a priori, but these two problems have relegated this taxon to an addendum in most classifications. Bather (1900, p. 203) included Mitrocrinus as an “incorrect or indeterminable name” by stating that it was “based on a six-rayed individual, probably abnormal, and a Periechocrinid or Carpocrinid” and Ubaghs (1978, p. T518) designated it as order, suborder, superfamily, and family uncertain.