The successful definition of chitinozoan genera depends primarily on the precision of the criteria used. A standardized morphological terminology based upon details from scanning electron microscope observations of the most representative taxa bearing these characters is therefore proposed. The 143 genera, or subgenera, described so far in the literature are reviewed in order to exclude invalid taxa and obvious junior synonyms. Particular attention is paid to preventing the overlap of generic definitions of the 56 genera ultimately retained. A brief account of the diagnostic features and stratigraphic range of selected genera is given, and basic information concerning the type material of these genera is listed. Finally, a suprageneric classification of the whole Chitinozoa group based on diagnostic features whose hierarchy is established on statistical and evolutionary grounds, is given. One new subfamily, Pogonochitininae, three new genera, Baltochitina, Hyalochitina, and Saharochitina, and a new species Baltochitina nolvaki, are defined. The subspecies Fungochitina fungiformis spinifera is elevated to a specific rank.

A new enigmatic Lower Cambrian fossil, Spygoria zappania, is described From the Nevadella zone (Botoman) of Lander County, central Nevada. In gross morphology, Spygoria fossils consist of stacks of small (5–10 mm in diameter) irregular calcified cups that are preserved in vertical, concave-up life orientation. Stacks are linked laterally into large monospecific bioherms which flourished in a shallow turbulent marine environment.

The Spygoria organism is interpreted as a metazoan which presumably inhabited the uppermost cup in each stack and periodically secreted new cups as it grew upward. Absence of holdfast structures suggest that the organism was held in place by sticky mud until opportunistically cementing to adjacent individuals. The affinity of Spygoria remains problematical, though we suggest that its stacked structure somewhat resembles the cone-in-cone structure of Cloudina, which formed similar dense thickets in shallow turbulent carbonate environments during the terminal Proterozoic.

Tectatodinium rugulatum (Hansen, 1977) McMinn, 1988, from the lower Danian of Denmark, is considered conspecific with, and a junior synonym of, the extant thermophilic species Tectatodinium pellitum Wall, 1967. However, the Danian material, based on holotype and topotype specimens, appears to show a degree of morphologic variability not seen in younger material. The accepted stratigraphic range base of Tectatodinium pellitum is now extended to the lower Danian, where this species appears to be a useful biostratigraphic marker in the Danish North Sea basin.

During growth of colonial corals, the basic organization of skeletal elements was determined by inherent factors, but arrangement of corallites within a colony could be affected if environmental change induced a modified growth form. Comparisons of internal and external characters during colony development indicate how environmental and genetic factors determined growth form. The results of these comparisons have implications for understanding of colony integration, functional morphology, and systematics.

This study is based on serially sectioned coralla of the cerioid tabulate Paleofavosites subelongus, from the uppermost Ordovician to lowermost Silurian of the east-central United States. Colony growth form resulted from changes in maximum growth angle of marginal corallites, and in the shape of the growth surface. These features were coordinated with corallite characters and were dependent on variation in corallite growth. At the same time that a colony became broader by expanding its maximum growth angle and developing a taller growth surface, its corallites became larger, more new corallites were initiated, and recently initiated corallites expanded more rapidly. When a colony's maximum growth angle was reduced and the growth surface became flatter, corallites also became smaller, fewer corallites were initiated, and those corallites that were recently initiated expanded slowly.

Genetic constraint of growth is illustrated by consistent patterns of initial colony growth, and by relationships among characters of internal and external morphology. Frequent small-scale variations in growth angle and growth surface height:width during astogeny indicate fluctuating environmental factors. Sedimentation and subsidence of the colony were probably the major environmental controls on form.

Palaeacmaea typica, the type species of the genus, and P. irvingi, the only other Late Cambrian taxon considered congeneric are redescribed herein. Their morphology suggests that they are neither Monoplacophora, where they are currently assigned, nor are they Mollusca. Specimens of P. irvingi demonstrate considerable variation in shape, interpreted as distortion of a flexible integument, of essentially no thickness. A neotype is designated for P. irvingi; it is interpreted as a medusiform fossil, possibly a cnidarian. Only the holotype of P. typica is known, but it shows comparable features. The genus and the family Palaeacmaeide are placed in Phylum Incertae Sedis. Four Ordovician species previously assigned to Palaeacmaea, show none of the characteristics noted, and they are tentatively reassigned to other genera.

New specimens representing species of Cyrtiopsis Grabau, 1923, described by Grabau (1931a) were recovered in samples from the Late Devonian deposits of the Changlongjie Member of the Xikuangshan Formation in central Hunan Province of South China. Associated Famennian age conodonts and morphotypes of the rhynchonellid brachiopod Yunnanellina lineage fix the ranges of species of Cyrtiopsis and related taxa in the Xikuangshan Formation within the interval of the Middle triangularis Zone through the Lower crepida Zone (early Famennian) in central Hunan Province.

Detailed study and comparison of external and internal shell structures of the type species of Cyrtiopsis Grabau, 1923, and related species described in Grabau (1931a) shows that Cyrtiopsis from South China includes the type species, C. davidsoni (embodied by the holotype), and C graciosa. Both of these species are shown to lack a delthyrial plate. Grabau's paratypes of C. davidsoni are considered to belong in Cyrtiopsis intermedia Grabau, 1931. The species C. kayseri Grabau, 1931, and C. shensiensis Grabau, 1931, are also deemed synonyms of C. davidsoni Grabau, 1923 (as restricted above). “Cyrtiopsis” intermedia differs from other species of Cyrtiopsis by development of a short delthyrial plate and its systematic position remains uncertain.

The genus Pseudocyrtiopsis is proposed with Cyrtiopsis spiriferoides Grabau, 1931, as the type. Pseudocyrtiopsis new genus is distinguished from Cyrtiopsis Grabau, 1923, by its alate hinge and development of a delthyrial plate. Comparisons of species of Cyrtiopsis from South China with cyrtospiriferid brachiopods identified as Cyrtiopsis by Crickmay (1952) demonstrate that none of the early Famennian species from western Canada can be assigned to the genus as revised here, although C. mimetes Crickmay, 1952, is closely related to “C.” intermedia Grabau, 1931.

A low-diversity brachiopod assemblage from the upper member of the Zorritas Formation in the Sierra de Almeida, northern Chile, further confirms the presence of Lower Carboniferous (Tournaisian) strata in that region. Key taxa include Schuchertella? sp., Chilenochonetes anna new genus and species, Paurorhyncha chavelensis (Amos), and Septosyringothyris covacevichi new species. Other elements of the assemblage, including Paraconularia sp., Posidoniella sp., Bellerophon (Bellerophon) sp., Eocanites sernageominus, and Imitoceras? sp. support this Early Carboniferous age assignment. Local distribution of taxa suggests small-scale environmental control. Rhynchonelloid and syringothyroid shells, many articulated, occur in lenticular sandstone bodies that were deposited in deltaic distributary channels; chonetids, schuchertellids and mollusc-bearing, iron-rich concretions are found in siltstones and mudstones that reflect interdistributary quiet-water settings and possibly a delta-front setting. Certain elements of this fauna are also present in northwestern Argentina and Peru, indicating a regional nearshore clastic regime. The closest correlation elsewhere is with the Tournaisian faunas of southeastern Australia, although analogous big-shell assemblages are found in lower Mississippian clastic strata of the central Appalachians, Ohio, and Indiana.

Dentalium martini Whitfield, 1882, is a calcareous worm tube, not a mollusk, and is placed in synonymy of Coleolus crenatocinctum Hall, 1879. The growth of D. martini mimics logarithmic curvature in the holotype, but in other specimens shape varies from irregularly curved to straight. A prime reason for reassignment is variation of the wall thickness around the circumference in D. martini, which in late Paleozoic and Recent scaphopods of the same size is of uniform thickness.

Maastrichtian ammonites are described from two areas in Pakistan. The upper part of the lower unit of the Korara Shale in the southern Pab Range, Kirthar Province, southern Balochistan, is dated as Late Maastrichtian, based on the presence of Menuites fresvillensis (Seunes, 1890), which is accompanied by abundant Indoceras baluchistanense Noetling, 1897, common Baculites ambatryensis Collignon, 1971, and rarer Neophylloceras surya (Forbes, 1846), Gaudryceras kayei (Forbes, 1846), Anagaudryceras politissimum (Kossmat, 1895), Kitchinites spengleri n. sp., Pachydiscus (Pachydiscus) noetlingi n. sp., Libycoceras acutodorsatus (Noetling, 1897), and Diplomoceras cylindraceum (Defrance, 1816). A smaller assemblage from the Mughal Kot Formation near Kach, Suleman Province, northern Balochistan cannot be dated more precisely than Maastrichtian from the presence of Pachydiscus (Pachydiscus) neubergicus (Hauer, 1858), the first occurrence of which has been provisionally adopted by the Subcommission on Cretaceous Stratigraphy as marking the base of the Maastrichtian stage. It is associated with numerous Eubaculites binodosus (Noetling, 1897).

A single specimen of a saleniid echinoid recently collected from the Late Maastrichtian of the type area of the Maastrichtian Stage is notable in being closely related to Salenia nutrix Peron and Gauthier, 1881. Representatives of the “nutrix group” have previously been recorded from the Late Cretaceous of the Mediterranean and north Africa. The occurrence in the type Maastrichtian of a representative of this group thus furnishes additional evidence of Tethyan incursions in the area during the Late Maastrichtian.

Phosphatic microfossils including copious microvertebrates and conodont elements indicative of the upper Icriodella discreta–Icriodella deflecta Zone (Aeronian) are found in a single bed of the Hendricks Formation, Burnt Bluff Group, Sturgeon Bay, Wisconsin. Scales of thelodonts, including Loganellia sp. cf. Loganellia siberica Karajute-Talimaa, 1978, and rare Valyalepis crista Turner (in Turner and Nowlan, 1995) predominate among the microvertebrate remains. Most scales are referred to Zuegelepis potanus Turner new genus and species. Associated with the thelodont scales are rare phosphatic fragments of questionable dermal “bone” and scales, possibly of heterostracan origin. Thelodont scales are also found in the Hendricks Formation at Fayette State Park, Michigan and in the subsurface Byron Formation (Burnt Bluff Group) in Schoolcraft County, Michigan.

A large ichthyosaur from the Los Molles Formation (Early Bajocian) of the Neuquén Basin, Northwestern Patagonia, Argentina, represents a new genus and species, Mollesaurus periallus. The holotype of M. periallus new species represents, along with the type of Chacaicosaurus cayi that was found at the same locality, the only diagnostic ichthyosaur specimens from the Aalenian-Bathonian interval.

In four genera of schizotheriine Chalicotheriidae—Moropus, Tylocephalonyx, Phyllotillon, and Ancylotherium–proximal and middle phalanges of digit II of the manus fuse to form a duplex bone. Fusion of proximal and middle phalanges of digit II of the pes also occurs in many species of these genera. Radiographic and sagittal-sectional study of the fused duplex phalanges of Moropus elatus and Tylocephalonyx skinneri shows that the joint between the two bones formed fully prior to fusion but had little movement. Fusion proceeded by external enthesial interactions at the insertion of the ligament capsule and by disruption of cortical bone with trabecular bridging along the internal part of the original articular surface. Cortical disruption is more rapid on the middle than on the proximal phalangeal component of the duplex. In M. elatus, the degrees of external and internal fusion roughly correspond, and a ventral surficial groove sometimes traces the former facet, whereas in T. skinneri external fusion is much more developed than internal fusion. Phalangeal fusion seems to have strengthened the digit against strong forces applied along the medial (radial or tibial) side of the foot.

We summarize faunal changes through the thickest and one of the most complete records of terrestrial vertebrates spanning Lancian (∼latest Cretaceous) and Puercan (∼earliest Paleocene) ages, the type Ferris Formation in the Hanna Basin, southern Wyoming. Observed faunal changes predate tectonic definition of local Laramide basins. Nonmammalian vertebrates exhibit no major changes in taxonomic composition below the Lancian-Puercan boundary; diversity of non-avian dinosaurs remains high within uppermost levels of the Lancian section. Nevertheless, dinosaurian extinction was not necessarily “catastrophic” within a biologically relevant interval. Primitive condylarths appear locally above the highest known dinosaurs, probably as immigrants. At least in this part of the North American western interior, the first evolutionary radiation of condylarths was subsequent to the last appearance of dinosaurs, not synchronous with or prior to it. Niche-partitioning among condylarths is first recorded near the boundary between Puercan Interval-zones Pu1 and Pu2 (early and middle Puercan time, respectively), by which time the first great mammalian diversification of the Cenozoic had begun. Major experimentations in dental morphology and increasing ranges of body sizes had developed within 400,000 years of the Lancian-Puercan boundary. We recognize no evidence suggesting that placental mammals were “recovering” from events that led to demise of the dinosaurs. The true diversity of marsupials and condylarths precisely at the Cretaceous-Tertiary boundary, throughout the western interior, remains unknown. We cannot, therefore, evaluate extensiveness of competition, if any, at that time among members of the two groups.

The shallow-marine Carmel Formation (Middle Jurassic) in central Utah hosts low-diversity trace fossil assemblages, including Arenicolites, Chondrites, Gyrochorte, Lockeia, Planolites, Protovirgularia, Rosselia, Scalarituba, Skolithos, Taenidium, and Teichichnus. Non specialized ichnotaxa with a remarkably small burrow size dominate the assemblages. The amount of bioturbation is lower than expected in comparison with modern shallow-marine carbonate environments. These ichnological features also are significantly different from those of other Jurassic shallow-marine carbonates. The trace fossils represent an environmentally stressed benthic community in a marginal marine, restricted setting, with salinities above normal marine and with depletion of oxygen in pore waters.