Sciadiocrinus Moore and Plummer is synonymized with Schistocrinus Moore and Plummer, with the name Sciadiocrinus retained by the Law of Priority. This synonymy is based on a reexamination of the type material, study of a previously undescribed ontogenetic sequence in S. tegillum Strimple and Moore, and close inspection of separate radial plates and anal-sac spines. The holotype specimen of the type species of Sciadiocrinus was incorrectly illustrated in the original description of the genus, and appears to be immature. The basal plates of this specimen are shown to be separated from each other by the junction of the radial plates with the infrabasals—a principal character in the original concept of Schistocrinus. The Sciadiocrinus tegillum hypodigm now includes specimens which also have relatively large radial–infrabasal sutures as well as individuals with little or no contact between these plates. Examination of this collection and previously described material shows that mode of arm branching, details of radial-plate articular facets, and some features of the anal-sac spines are also equivalent in the two genera.

Sciadiocrinus, presently classified in the family Pirasocrinidae, is distinct from all known pirasocrinid taxa in a number of morphological characters. We believe the genus should be removed from the Pirasocrinidae, and recommend its assignment to the family Anobasicrinidae based primarily on similarities in arm structure. The remarkable convergence between Sciadiocrinus and the Pirasocrinidae emphasizes the adaptive significance of the spinose, umbrella-like anal-sac roof, which apparently served as a deterrent to predators.

Recent studies of drill-cores and outcrops have resulted in the discovery of previously unknown, taxonomically diverse, graptolite faunas in the late Middle (Mohawkian) and early Late Ordovician (Cincinnatian) strata in the Cincinnati region, the type area of the Cincinnatian Series. These faunas contain several zonal indices and other biostratigraphically important species that are used for close correlation with the standard graptolite zone succession in New York and Quebec. The new data show that the base of the Cincinnatian Series in its type area is near the middle of the Climacograptus (Diplacanthograptus) spiniferus Zone. Significantly, about a dozen Cincinnati region graptolite species are shared with apparently coeval strata in the standard Australian graptolite zone succession in Victoria, and this key faunal evidence indicates that the base of the typical Cincinnatian corresponds to a level near the middle of the Climacograptus (Climacograptus) baragwanathi Zone (Ea2) of the Eastonian Stage. This represents a considerable revision of some recently published correlations of the basal Cincinnatian in terms of the Australian graptolite zone succession.

A single specimen of Cyclolobus persulcatus Rothpletz (1892), a species interpreted as a primitive member of the genus, is described from the Cherrabun Member of the Hardman Formation, Liveringa Group, Canning Basin, Western Australia. It is the youngest Permian ammonoid known from Australia. Type and other representatives of C. persulcatus from Indonesia (Timor) are part of the “Amarassi fauna,” which is considered post-Guadalupian. Cyclolobus is sporadically abundant and widely distributed in the Dzhulfian Stage, and probably extends into the overlying Dorashamian Stage.

The hyolith orders Camerothecida Syssoiev and Diplothecida Syssoiev are here incorporated into the order Hyolithida Matthew. Morphologic features used to distinguish Camerothecida and Diplothecida are interpretive reconstructions of features presumed to have been present but not actually preserved on any existing specimens. The few morphologic features retained by those fossils are consistent with assignment to the Hyolithida. Poor preservation of the types of Hyolithes (Camerotheca) gracilis Matthew and Diplotheca hyattiana Matthew, which formed the basis for those two orders, as well as those of Hyolithes (Camerotheca) micmac Matthew in Walcott, Hyolithes acadica Hartt in Walcott, and Hyolithes matthewi Sinclair, renders generic assignment of these species uncertain. Hyolithes matthewi Sinclair is assigned to Tulenicornus Val'kov with question, and Hyolithes danianum Matthew in Walcott is here transferred to Nitoricornus Syssoiev.

New species of Aphelognathus, Belodina, Taoqupognathus, and Yaoxianognathus have been identified in the Late Ordovician Cliefden Caves Limestone Group in central-western New South Wales, Australia. Of the Aphelognathus species, Aphelognathus percivali n. sp. and A. webbyi n. sp. occur in the basal Gleesons Limestone Member and A. packhami n. sp. and A. stevensi n. sp. occur 30 m higher in the Wyoming Limestone Member. It seems likely from the similarity of several of the elements that A. packhami is closely related to A. percivali, and A. stevensi to A. webbyi. Yaoxianognathus wrighti n. sp. occurs in the Gleesons Limestone Member but not in the Wyoming Limestone Member. Belodina confluens, Belodina hillae n. sp., Belodina n. sp., Panderodus gracilis, Taoqupognathus philipi n. sp., and Phragmodus? tunguskaensis occur at both horizons. The conodonts suggest a middle to late Caradocian (mid-Shermanian to mid-Edenian) age for the lowest part of the Cliefden Caves Limestone. The occurrence in southeastern Australia of the forms Taoqupognathus, Yaoxianognathus, and Phragmodus? tunguskaensis suggest affinities to coeval faunas in China and eastern Siberia. The four new species of Aphelognathus are distinct from known species in the Late Ordovician of North America and Europe but they may help characterize a paleobiogeographic region that includes eastern Australia and southeast Asia.

An abundant, low diversity, poorly preserved Late Permian ostracode faunule was recovered from residues of dissolved limestone. Collections are from the Corumbataí Formation exposed near Conchas, about 194 km northwest of São Paulo and from a borehole into the upper part of the Corumbataí Formation. Although the Corumbataí Formation has been interpreted mainly as a restricted marine-transitional offshore/shoreface and tidal-flat deposit, the ostracodes represent nonmarine taxa. Steinkerns of Candona, Cypridopsis?, Darwinula?, Gutschickia?, and genus unknown are illustrated in open nomenclature; they indicate freshwater influences. Several Permian marine genera from lower Gondwana (=Carboniferous-Permian), illustrated in open nomenclature, show that their steinkerns would differ from those illustrated here from Brazil. Although the Late Permian drainage from the north into the Paraná Basin has been considered to have been meager, rivers from the north must have supplied sufficient water to freshen the margins of the basin so that immigration of nonmarine ostracodes occurred.

Based on the similarity of the distinctive lateral outline of the Brazilian specimens to the nonmarine living genus Candona, the stratigraphic range of the genus is tentatively extended into the Permian.

Detailed qualitative analysis of the Pa element and multielement analysis emphasizing the associated Pb element have led to the present revision of the Frasnian species of Ancyrognathus. Diagnostic characters of the Pa element, such as the platform outline, carinal pattern, and shape of the pit, as well as salient features of the Pb element, are the basis of this revision. As a consequence, the restriction in the definition of A. triangularis, formerly a heterogeneous concept including several discrete species, has in turn led to the recognition of a substantially increased number of species of Ancyrognathus.

The lowest occurrence of Ancyrognathus primus is used here to delimit the base of Zone 6 of the Montagne Noire Frasnian sequence. The exact relationship of the Montagne Noire zonation to the published standard zonation is problematical. For example, the base of the range of A. triangularis is possibly above the zone for which it is the nominal species in the standard zonation. Two new species are named herein, A. coeni and A. seddoni, both of which have been widely illustrated in the literature, and three new species are recognized in open nomenclature.

Specimens of Sphenothallus ruedemanni (Kobayashi, 1934), which were originally assigned to Serpulites, are described from the Asaphellus Zone (Tremadocian) of the Dumugol Formation, Korea. Previously, Sphenothallus was known to occur in Middle Ordovician to Permian rocks, thus making Sphenothallus ruedemanni the earliest record of this genus. This species is characterized by a distally expanding tube with smooth to variously wrinkled surface. The tube is presently composed of quartz, chlorite, and/or muscovite, which appear to have replaced calcium phosphate. The zoological affinity of this tube-building animal is still uncertain.

The dorsal cups of 17 calceocrinid species illustrate the relations between ontogeny and phylogeny for this unique family. Paedomorphosis in conjunction with increasing adult body size comprises the dominant pattern. During evolution, the plate structure of the dorsal cup was rearranged so that the hinge of advanced crinoids resembles the juvenile configuration of more primitive species. Consideration of allometric equations dealing with the size and shape of the dorsal cup and hinge suggests that most changes were caused by displacements of the initial intercepts and offsets of timing in development. The growth of the hinge moment of typical taxa produces hinges that are functionally equivalent in adult crinoids of different body sizes.

Previously poorly known Devonian actinocerids are described from Gedinnian (Early Devonian) strata of the Fukuji Formation, Gifu Prefecture, central Japan. They include two new species, Ormoceras japonicum and Metarmenoceras kameii. Two specimens of a probable new species of the family Ormoceratidae are also recorded and illustrated. This is the first detailed systematic report of actinocerids from Japan.

Juvenile specimens of the Paleocene–Eocene pantodont Coryphodon provide more extensive ontogenetic information for this genus than is available for other Paleocene–Eocene mammals. The dental eruption sequence for Coryphodon is: 1) (DC11, DI1–31–3); 2) DP44; 3) DP33; 4) DP22; 5) (M11, I33); 6) DP11, 7) M22; 8) P44; 9) P33; 10) (P22, I11?); 11) C11; 12) (M33, I22) (eruption sequence of tooth positions in parentheses is uncertain). The DP11 of Coryphodon do not have permanent successors. No significant, qualitative morphological variation can be detected in deciduous cheek teeth of Coryphodon, and metric analysis of these teeth failed to detect taxonomically significant differences. The ontogenetically youngest Coryphodon is known from parts of a skeleton of an individual perhaps less than three years old at the time of death. This skeleton and other partial juvenile skeletons suggest that juvenile Coryphodon grew quickly and approached near-adult proportions before the deciduous dentition was lost or the epiphyses of the long bones began to fuse.

The barnacle fauna of the Miocene Bear Lake Formation of the Alaska Peninsula includes Chirona (Chirona) alaskana n. sp., and three species of Balanus Da Costa conspecific with or related to the extant species Balanus balanus (Linnaeus), B. nubilus Darwin, and B. crenatus (Bruguière). Although the Bear Lake fauna lived in warm temperate waters, its modern counterparts are found primarily in boreo-arctic and cool temperate regions of the North Pacific and North Atlantic Oceans. Miocene barnacle faunas in Japan are similar to those of the Alaska Peninsula, lacking relatives of B. nubilus, but including Semibalanus Pilsbry, which does not appear until the Pleistocene in the eastern Pacific. Elements of this boreo-Arctic fauna do not appear in the North Atlantic basin until the Pleistocene, suggesting migration of the fauna into the Atlantic with the opening of the Bering Straits.

A fragmentary tyrannosaurid skull and postcranial skeleton from the Kirtland Shale of northwestern New Mexico is the most complete specimen of a carnivorous dinosaur known from these strata. The specimen is identified as Aublysodon cf. A. mirandus on the basis of its narrow frontals, V-shaped frontal-parietal suture, and nondenticulate incisiform premaxillary tooth. The D-shaped cross section of the premaxillary tooth, rugose postorbital, well-developed footed pubis, and proximally constricted third metatarsal confirm the assignment of Aublysodon to the Tyrannosauridae. The limb bones are gracile and similar in proportions to those of Albertosaurus; however, the tibia and metatarsals are shorter relative to the femur. The distal end of the tibia exhibits a unique medial emargination not reported in other tyrannosaurids.

Two new species of Eomyelodactylus, E. sparteus and E. uniformis, are described from the Lower Silurian of New York. Macnamaratylus murrayi Bolton from the Lower Silurian of Ontario, Canada, is redescribed and assigned to Eomyelodactylus. Together, these species permit detailed description of this poorly known myelodactylid genus.

In paleontological investigations the number of individuals of a particular species, ni, is often expressed as a proportion of the total number of individuals, ∑i=1S ni = n, for all, S, species. This proportion, p = ni/n expressed in percent, is referred to by various authors as percent species, relative abundance, percentage abundance, species frequency, fractional abundance, and so on. Naturally, researchers are interested in the confidence limits that can be placed on these estimates, and in the number of individuals required to obtain them. The binomial distribution was used by Dryden (1931), Dennison and Hay (1967), Wright and Hay (1971), and Patterson and Fishbein (1989) for this purpose.

Odontopleura (Odontopleura) arctica, a new species of odontopleurine trilobite, is described from the Canadian Arctic. A method of cladistic analysis is detailed. Parsimony analysis should be performed treating all characters as unordered. The universe of directed trees implied by the resulting rootless network(s) can then be examined and a preferred tree selected by a criterion of congruency. Namely, the most parsimonious directed tree that accommodates the most congruent arrangement of character-states should be taken as the preferred cladogram. Since this is essentially a general congruency method operating within the constraints of parsimony, it is termed “constrained congruency.” The method is applied to the genus Odontopleura, resulting in the recognition of two major species groups, the nominate subgenus and Sinespinaspis n. subgen. Odontopleura (Ivanopleura) dufrenoyi Barrande is tentatively included in the genus, but considered too poorly known for cladistic analysis. Species assigned to Odontopleura (Odontopleura) include Odontopleura ovata Emmrich, Odontopleura brevigena Chatterton and Perry, Odontopleura (Odontopleura) arctica n. sp., and Diacanthaspis serotina Apollonov. Species assigned to Sinespinaspis n. subgen. include Taemasaspis llandoveryana Šnajdr, Odontopleura greenwoodi Chatterton and Perry, Odontopleura maccallai Chatterton and Perry, and Odontopleura nehedensis Chatterton and Perry. Odontopleura bombini Chatterton and Perry is tentatively placed in synonymy with Odontopleura nehedensis. The genus had a wide distribution throughout the Early and Middle Silurian, due to preferences for deep-water, distal shelf or shelf-slope transition zone habitats.

Sixty-five fossil brachyuran crabs, collected from rocks of the Orca Group, Tokun Formation, and Poul Creek Formation, have been assigned to six species, five of which were described previously. One of these, Pilumnoplax hannibalanus, is reassigned to Neopilumnoplax. Morphologic descriptions of Raninoides vaderensis, Eumorphocorystes naselensis, Portunites alaskensis, and Branchioplax washingtoniana are emended. Orbitoplax plafkeri n. gen. and sp. is described from the Poul Creek Formation on Wingham Island. The diagnosis of age for the Orca Group has been problematic. However, the well-preserved brachyurans, Branchioplax washingtoniana, Neopilumnoplax hannibalanus, and Raninoides vaderensis, provide corroborative evidence for an Eocene or older age for the rocks. Alaskan decapods include species common to the entire Pacific coast north of California, as well as species endemic to Alaska.

Representatives of 12 conodont species, including Oulodus equirectus n. sp., have been recovered from the Silurian Lilley Formation, Lilley–Peebles transition unit, and Peebles Dolomite at six localities in southern Ohio. The Lilley, Lilley–Peebles transition unit, and Peebles belong in the Kockelella ranuliformis–K. amsdeni to Ozarkodina? crassa Chronozone and are late early to middle Wenlockian in age.

The Lilley is conformable and transitional with the underlying Bisher Formation and overlying Peebles. The unconformity between the upper Niagaran Peebles and overlying lower Salinan Greenfield Dolomite represents middle Wenlockian to late Ludlovian or early Pridolian time.

The Lilley, Lilley–Peebles transition unit, and Peebles were deposited in a gradually shoaling sea that was controlled by eustatic sea-level fall during the late early to middle Wenlockian. Uplift along the Cincinnati Arch, probably due to northward tilting of the arch, began during/after deposition of the Peebles in the middle Wenlockian. The combined effects of uplift and eustatic sea-level fall caused the sea to withdraw from southern Ohio. The Peebles was exposed and eroded prior to return of the sea to begin Greenfield deposition in the late Ludlovian or Pridolian (Ozarkodina remscheidensis Chronozone).

Three species of Upper Pennsylvanian crinoids, two inadunates and one flexible, exhibit a sufficiently complete growth series to describe and quantify their ontogeny. Apographiocrinus typicalis (Moore and Plummer), Erisocrinus typus (Meek and Worthen), and Euonychocrinus simplex (Strimple and Moore) were collected from the middle shale of the Millersville Limestone Member of the Bond Formation at the Charleston Stone Quarry, Coles County, Illinois. Ten other crinoid species were collected in insufficient numbers for growth studies. Both bivariate and multivariate statistical procedures were used to analyze the growth of these crinoids.

In the inadunate crinoids skeletal growth was highly coordinated in the dorsal cup and cup plates. Arm length increased by addition of secundibrachials. Food groove width increased almost three times from immature to adult stages, thus allowing a larger range of food particles to be consumed by adults. Growth of the cup is isometric in E. typus and slightly anisometric in A. typicalis. Primibrachials in both species develop anisometrically. Immature specimens possess long, slender primibrachials, with the A ray plate being longest. In maturity, the primibrachials become equidimensional and equalized in all rays. The A ray arm is followed by the C and D ray arms, and finally the B and E ray arms, in sharp contrast to arm development in disparid inadunates. Pinnules appear late in the immature stage of growth. Primary emphasis on the expansion of the arms in young inadunates demonstrates a rapid establishment of a filtration-fan mode of feeding. Subsequent development involves widening of the plates for strength and support of the arms and to accommodate wider food grooves that permit a larger array of food particles to be captured.

The flexible crinoid, E. simplex, experienced a less correlated pattern of growth. Cup plates and arms grew isometrically and all arms were added simultaneously. Development suggests that flexibles fed differently than the associated inadunates and the cup may have played a less important role in functioning of the calyx.

The upright, elevated growth pattern of stalked crinoids exposed them to a sequence of competitive interactions with other epifaunal animals that had important adaptational ramifications for their evolution, diversity, and extinction. The fact that most living crinoids, stalked and unstalked, have abandoned a permanently fixed place of growth may have been an advantageous factor in their survival.