During preparation of a manuscript on new collections of Upper Cambrian trilobites from the Threadgill Creek section in central Texas (Longacre, 1970, text-fig. 6), a new trilobite species Ptychopleurites spinosa was discovered that can be used to recognize a revised base to the Saukia Zone (Trempealeauan Stage) in central Texas. This species is represented in central Texas by numerous, well-preserved cranidia and librigenae, but no pygidia have been recovered. Recently Ptychopleurites spinosa was also identified in a collection of trilobites of the partly correlative Illaenurus Zone (= lower part of Saukia Zone) from the type section of the Deadwood Formation in the Black Hills of South Dakota. This work is part of a paper that will describe the latest Franconian and Trempealeauan trilobites from the Deadwood Formation, using collections made by Dr. Christina Lochman-Balk. Ptychopleurites spinosa is represented in the Black Hills by incompletely preserved cranidia and well-preserved librigenae. Because it is not known which of these two papers will be published first, it was decided to establish Ptychopleurites spinosa as a new species with one of the better Texas cranidia as the holotype and the Black Hills material as part of the suite of paratypes.

Cyclocystoids are one of the rarest and most enigmatic of the extinct echinoderm groups. Despite recent systematic revision (Smith and Paul, 1982), their basic anatomy and functional morphology remain poorly understood. Smith and Paul (1982) recognized eight genera and 39 species ranging in age from Lower Ordovician to Late Devonian. Since then, one new genus and species, Monocycloides oelandicus, has been established by Berg-Madsen (1987), and the range of the genus Sievertsia has been extended to the Middle Devonian of the U.S.A (Fluegeman and Orr, 1990). In addition, undescribed cyclocystoid marginal ossicles have been found in the Lower Carboniferous of Ireland (G. D. Sevastopulo, personal communication). Here we record an additional new species from the Late Ordovician of Kentucky.

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.

Spiral coprolites from the Upper Cretaceous of North America are poorly known. Enterospirae (fossilized intestines) reported from the Upper Cretaceous Niobrara Formation of western Kansas (Stewart, 1978) were disputed by McAllister (1985), who felt they represented spiral coprolites similar to those described from the Permian by Neumayer (1904). Previously described coprolites from the Upper Cretaceous of Alberta are small, unstructured, ellipsoidal forms thought to derive from a crocodilian or terrestrial, carnivorous reptile of necrophagic or piscivorous habits (Waldman, 1970; Waldman and Hopkins, 1970).