The Little East Lake Formation represents a spectrum of Late Ordovician (Ashgill) nearshore environments. These physical environments are characterized by a variety of quartz- and feldspar-rich sandstone and slate. Depositional environments include neritic nearshore, beach, tidal flat, and alluvial(?). The beach and neritic nearshore environments contain a variety of fossil invertebrates. The majority of the brachiopod fauna is confined to two taxa: Eodinobolus rotundus Harper, 1984, and Dalmanella testudinaria ripae Mitchell, 1978 (in Cocks, 1978). Some of the specimens have been broken and abraded suggesting transport within the beach swash zone. Gastropods include Lophospira cf. L. milleri (Hall), Lophospira(?), Trochonemella cf. T. notabilis (Ulrich and Scofield), and Daidia cerithioides (Salter). Tidal-flat environment contains the trace fossils Palaeophycus and Planolites.

The Late Ordovician (Caradoc and Ashgill) sedimentary basins developed subsequent to the collisional Taconian orogeny, wherein an arc accreted to the eastern Laurentian margin. Prior paleomagnetic reconstructions place the southeastern continental margin of Laurentia at approximately 25° south latitude during the Late Ordovician. Using these reconstructions, the siliciclastic Ashgill rocks discussed here would have been deposited in an elongated, northeast-trending basin on the southeastern Laurentian margin. The fauna developed along this margin, but in contrast to possibly adjacent Irish and Scottish assemblages, was located in much shallower water.

Rugose and tabulate corals from the Lower Permian (Wolfcampian) part of the Bird Spring Group in the Providence Mountains, San Bernardino County, southeastern California, comprise eight species in eight genera. Heritschioides mckassoni n. sp. is the lowest stratigraphic record for this index genus on the undoubted shelf of western North America. Paraheritschioides applegatei n. sp. is the first record for the genus in southern California. Neomultithecopora providensis n. sp. is a second species for the genus in the southern Great Basin. The other five species provide close ties to previously described faunas from the Spring Mountains and the Arrow Canyon Range of southwestern and southeastern Nevada. The combined Wolfcampian coral faunas of these three areas are somewhat closer at the genus and species level to the McCloud Limestone Wolfcampian faunas of northern California than to the Wolfcampian shelf faunas in east-central Nevada. Additional species present in the combined faunas are known originally from the Wolfcampian of central Nevada and Kansas and a genus is not otherwise known south of British Columbia. The faunas suggest a subprovince of the Durhaminid Coral Province for the southern California and southern Nevada area and perhaps imply partial isolation from the more northerly parts of the province by land barriers such as the Antler Highlands.

To document evolutionary patterns in late Cenozoic Caribbean reef corals, we compiled composite stratigraphic ranges of 49 genera and 175 species using Neogene occurrences in the Cibao Valley sequence of the northern Dominican Republic and faunal lists for 24 Miocene to Recent sites across the Caribbean region. This new compilation benefits in particular from increased sampling at late Miocene to early Pleistocene sites and from increased resolution and greater taxonomic consistency provided by the use of morphometric procedures in species recognition.

Preliminary examination and quantitative analysis of origination and extinction patterns suggest that a major episode of turnover took place between 4 and 1 Ma during Plio-Pleistocene time. During the episode, extinctions were approximately simultaneous in species of all reef-building families, except the Mussidae. Most strongly affected were the Pocilloporidae (Stylophora and Pocillopora), Agariciidae (Pavona and Gardineroseris), and free-living members of the Faviidae and Meandrinidae. At the genus level, mono- and paucispecific as well as more speciose genera became regionally extinct. Many of the extinct genera live today in the Indo-Pacific region, and some are important components of modern eastern Pacific reefs. Global extinctions were concentrated in free-living genera. During the turnover episode, no new genera or higher taxa arose. Instead, new species originated within the surviving Caribbean genera at approximately the same time as the extinctions, including many dominant modern Caribbean reef-building corals (e.g., Acropora palmata and the Montastraea annularis complex).

Excluding this episode, the taxonomic composition of the Caribbean reef-coral fauna remained relatively unchanged during the Neogene. Minor exceptions include: 1) high originations in the Agariciidae and free-living corals during late Miocene time; and 2) regional or global extinctions of several important Oligocene Caribbean reef builders during early to middle Miocene time.

Until the late 1960's, most of Nicholson's types of Paleozoic bryozoans were not available for study. We present a set of coded characters of many of Nicholson's types, which should assist in bringing his species into conformity with current taxonomic standards so that his species can be consistently recognized and used in biostratigraphic, paleobiogeographic, and evolutionary studies.

Cladistic and phenetic analyses of these species permit comparisons between inferred phylogenies of Nicholson specimens, adaptive morphospace, and treatise-based systematic relationships. Specimen-based cladistic and phenetic analyses of Nicholson's species both produce clusters that are congruent with existing family-level taxonomic assignments of species in the collection. However, cladistic analysis more fully retrieves the pattern of branching, or degree of relatedness, among higher taxa. Phenetic clusters represent adaptive peaks in morphospace for these specimens, but higher level “phenons” are strongly affected by multiple evolution of the same character states.

A new genus and species of obolellid brachiopod, Brevipelta chouberti, is described from the Early Cambrian of Morocco. It is a useful index fossil for the upper Choubertella Zone and the Daguinaspis Zone in Morocco. Additionally discussed are taphonomic aspects that lead to the question whether the shell may have been weakly calcified compared to other obolellid brachiopods and the calcareous part may have been composed of aragonite crystallites, or whether the preservation of Brevipelta is due to facile solubility of a calcitic shell substance. Brevipelta chouberti represents not only the oldest described Early Cambrian brachiopod from Africa, but one of the oldest obolellid brachiopods known worldwide.

The ontogenies of Prorensselaeria and Nanothyris, described here for the first time, suggest that Cloud's Dielasmatidae are closely affiliated phylogenetically with Cloud's Centronellidae. This is based on the fact that the type species of Nanothyris goes through an initial mutationellinid (Cloud's Dielasmatidae) growth stage before reaching its adult rensselaerinid (Centronellidae) growth stage. The ontogeny of Prorensselaeria requires that it be transferred from the Globithyrinae (Rhipidothyrididae) to the Mutationellinae (Meganteridae [=Cloud's Dielasmatidae = Stehli's Mutationellidae]). Further consideration of their ontogenies permits the transfer of Meganteris, Meganterella, and Reeftonella to the Meganterinae of the Meganteridae. It is recommended, because of the placement of Meganteris in the Meganterinae, that the term Meganteridae replace Mutationellidae, and Mutationellinae be restricted to costate Meganteridae. The subfamily Adreninae of the Meganteridae (=Stehli's Mutationellidae) is proposed to include Adrenia, Cydimia, Micidus, Sturtella, Barbarothyris, and Lingshanella.

The information developed here permits one to conclude that there are two kinds of families: 1) those generated by directional selection, involving major adaptive radiations, the type generated by quantum evolution in Simpson's sense; and 2) those generated by minor developmental changes, that do not involve major adaptive radiations, although they do result in morphological and biogeographical differences great enough to warrant the erection of families.

The systematics of vermetid gastropods is in a shambles, with few genera defined by valid autapomorphic characters. Heretofore, the genus Petaloconchus has been included among the few adequately characterized groups, thanks to possession of a double internal lamina on the middle whorls. Yet abundant anecdotal information has been available for 100 years on the absence of laminae in high percentages of individuals within samples, and in entire populations that must be placed within the genealogical nexus of Petaloconchus. I demonstrate that such a nonlaminate population exists within the very material used to define the type species of the genus, Pliocene Petaloconchus sculpturatus Lea, 1843, from the Gulf and Atlantic Coastal Plain of the United States. I use X-radiography and multivariate biometry to show that this population from the Pliocene Jackson Bluff Formation at Jackson Bluff, Florida, is fully alaminate, but otherwise indistinguishable from P. sculpturatus. After considering a range of solutions, I name this population as a new subspecies, Petaloconchus sculpturatus alaminatus. I discuss theoretical and practical issues arising from populations that lack the defining feature of their genus.

Representatives of the ancestral cyclolobin ammonoid Demarezites Ruzhencev (Cyclolobidae) are known from only a few localities in North America where they occur as rare faunal elements. Demarezites furnishi n. sp. is based on a single specimen from “Middle” Permian (Roadian) strata in the Meade Peak Member of the Phosphoria Formation in eastern Idaho. Several specimens of the closely comparable Demarezites n. sp., described herein, are known from the Pipeline Shale Member of the Brushy Canyon Formation in West Texas.

New Devonian fossil material from Bolivia includes internal molds of two species of paleotaxodont bivalve, Palaeoneilo musculosa (Knod) and P. pondeana (Hartt and Rathbun), with numerous accessory muscle scars. The unusual pattern of these scars appears to have been derived from excessive splitting. These muscle scars are described and a tentative interpretation is made. An adaptative role cannot be determined with certainty and it appears that these patterns were short-lived novelties without later success.

Maastrichtian strata of the Zumaya-Algorta Formation of southwestern France and northeastern Spain record a major pulse of extinction among inoceramid bivalves well before the Cretaceous–Tertiary (K–T) boundary. Inoceramids are the most abundant macrofossils preserved in the study sections; at least six species of Inoceramus [I. (Endocostea) aff. I. (En.) balticus Giers, I. (En.) pteroides Giers, I. (Platyceramus) aff. I. (Pl.) cycloides Wegner, I. (Trochoceramus) nahorianensis Kociubynskij, I. (Tr.) morgani Sornay, and I.(?) goldfussianus d'Orbigny] are common to abundant in lower Maastrichtian strata. However, all six species disappear over a few tens of meters of section near the base of the upper Maastrichtian, as defined by the first appearance of the planktonic foraminifer Abathomphalus mayaroensis. Tenuipteria argentea (Conrad), which has not been recovered from the lower Maastrichtian portions of the sections, occurs at low abundances through the upper Maastrichtian, disappearing within 10 cm of the K–T boundary.

The mid-Maastrichtian extinction interval among inoceramids occurs within the upper Globotruncana gansseri to lower Abathomphalus mayaroensis planktonic foraminiferal zone, in nannofossil zone 24 to 25A, in the Anapachydiscus fresvillensis ammonite zone, in magnetochron 31N, and near the base of a change in slope of the seawater strontium curve, all as recognized by previous studies in one or more of the study sections. Whereas the new data presented here are not global in extent, the observed distribution of inoceramids may be the local manifestation of global oceanic changes during the mid-Maastrichtian.

The distributional patterns of reticulate sculptures, corresponding to those of the underlying epidermal cells, of two Baffinicythere species (Ostracoda, Crustacea) are discussed from a geometrical point of view to understand whether they are under some rule or not. Reticulation geometry has been quantified by applying the method of Dirichlet domains defined as convex polygons, each being demarcated by bisectors normal to the lines connecting neighboring pairs of points. Studies of the distributional patterns of reticulation during growth reveal that these polygons become closer to Dirichlet domains and are dominated by hexagonal or subcircular fossa outlines toward the adult stage, and ultimately reach an equilibrium and stable pattern at maturity.

Examination of extremely well-preserved cuticle samples from the Maastrichtian retroplumid crab, Costacopluma mexicana Vega and Perrilliat, collected in the Difunta Group in Nuevo León State, Mexico, documents the preservation of corpses in an anoxic microenvironment produced by decomposition of soft tissue of the organisms. All four cuticular layers, epicuticle, exocuticle, endocuticle, and membranous layer, as well as pore canals and tegumental glands, can be recognized. There is no evidence of resorption that accompanies molting. X-ray analysis of the cuticle indicates that the organic matrix was replaced by carbonate-hydroxyapatite, that the original calcitic material was replaced by quartz, and that the replacement proceeded from the outer and inner surfaces of the cuticle toward the interior. The specimens were interpreted to have been preserved in an organic-rich, restricted lagoon in which pH was changed by periodic influxes of fresh water.

Borealarges n. gen. (type species B. reedi n. gen. and sp.) is a group of trochurine trilobites of mainly northern Laurentian distribution, closely related to both Richterarges Phleger and Terranovia Maximova. Richterarges is restricted to a Laurentian Ludlow-Přídolí clade of unambiguous monophyly. Taken together, the genera form a monophyletic subdivision of Trochurinae. Phylogenetic relationships within this clade are poorly resolved. The precise relationships of some members of the group are difficult to determine at present, and these species are referred to Borealarges sensu lato. Members of Borealarges are ubiquitous elements of silicified Wenlock–Ludlow trilobite faunas contained in debris flows of the Cape Phillips Formation of the central Canadian Arctic. At present, known post-Wenlock diversity of Borealarges is exclusively northern Laurentian, although this may be a function of lack of study in other areas. New species include B. reedi, B. morrisoni, and B. tuckerae, and B. s.l. B. calei. Borealarges mikulicorum (Perry and Chatterton) is revised.

Tyrannosaurids are a well-supported clade of very large predatory dinosaurs of Late Cretaceous Asiamerica. Traditional dinosaurian systematics place these animals within the infraorder Carnosauria with the other large theropods (allosaurids, megalosaurids). A new cladistic analysis indicates that the tyrannosaurs were in fact derived members of the Coelurosauria, a group of otherwise small theropods. Despite certain gross cranial similarities with the large predators of the Jurassic and Early Cretaceous, the Late Cretaceous tyrannosaurids are shown to be the sister group to ornithomimids and troodontids, which share a derived condition of the metatarsus. This clade is found to be nested within Maniraptora, which is a more inclusive taxon than previously recognized. The atrophied carpal structure found in tyrannosaurids and ornithomimids is derived from a maniraptoran condition with a large semilunate carpal, rather than from the plesiomorphic theropod morphology.

The taxa “Carnosauria” and “Deinonychosauria” (Dromaeosauridae plus Troodontidae) are shown to be polyphyletic, and the Late Jurassic African form Elaphrosaurus is found to be the sister taxon to Abelisauridae rather than a primitive ornithomimosaur. Purported allosaurid-tyrannosaurid synapomorphies are seen to be largely size-related, present in the larger members of both clades, but absent in smaller members of the Tyrannosauridae. The remaining giant tetanurine theropods (Megalosaurus and Torvosaurus) were found to be progressively distant outgroups to an allosaurid-coelurosaur clade. The inclusion of the Tyrannosauridae within Maniraptora suggests a major adaptive radiation of coelurosaurs within Cretaceous Asiamerica comparable to contemporaneous radiations in various herbivorous dinosaurian clades.

The Coelophysis dinosaur quarry at Ghost Ranch, near Abiquiu, New Mexico, is unique among Triassic fossil sites for its yield of numerous complete and partial skeletons of a single species of theropod dinosaur (Coelophysis bauri). Since its discovery in 1947 by E. H. Colbert in the red siltstone beds of the Upper Triassic Chinle Formation, the quarry has yielded the remains of at least 1,000 individuals from approximately 30 cubic meters of excavated material. The main bone-bearing strata are abandoned channel deposits that are part of a siltstone overbank sequence. The Coelophysis remains found at the quarry are remarkably whole and well preserved, though they range in degree of articulation from complete skeletons to isolated limbs and bones. Skeletons, partial skeletons, and bones are crudely aligned and show little evidence of predator or scavenger disturbance or surface weathering. Geologic and taphonomic evidence suggests that the dinosaurs preserved in the Ghost Ranch quarry were transported to the site as carcasses by fluvial currents. The carcasses blocked a small channel and were subsequently buried by silts. Petrographic study and neutron activation analysis reveal no evidence of volcanic ash, paleopathologic osteology, or unusual chemistry in the quarry bone and sediments. The virtual monospecificity, taphonomy, and ecology of the assemblage suggest that the dinosaurs perished due to a regional environmental crisis, such as drought.

A recently discovered vertebrate fossil-bearing locality in the Fleming Formation of easternmost Texas has revealed a highly diverse fauna that contains a minimum of 44 early Miocene vertebrate taxa. At least 17 different species of lower vertebrates were recovered including five fish, two amphibians, one lizard, two snakes, at least five chelonians, and two crocodilians. A tiny boid that compares favorably with Anilioides nebraskensis is the first record in the Gulf Coastal Plain, and remains of a large aquatic turtle referred to the genus Dermatemys possibly represent its first fossil occurrence. Other rare genera represented include the largemouth bass Micropterus, possibly the snook Centropomus, and the crocodilian Gavialosuchus. In addition, temporal and spatial range extensions are recorded for Micropterus and Alligator olseni. These taxa, along with the mammalian component to be discussed elsewhere, document the rare preservation of a forested subtropical to tropical coastal lowland paleoenvironment and provide evidence to imply that separation into mid-continent and coastal plain paleobiogeographic provinces had not yet occurred.

The Trinity Division exposures at Junction, Kimble County, Texas, yield a rich charophyte flora dominated by clavatoraceans. The presence of Atopochara trivolvis ssp. trivolvis (Peck, 1938) Grambast, 1968, and Clypeator corrugatus (Peck, 1941) Grambast, 1962, indicates an Aptian age for these strata and makes them the continental equivalent of the Lower Glen Rose. Atopochara trivolvis, whose type-material was recovered from the Trinity in a deep well in southern Texas, is known from numerous freshwater to oligohaline lakes from the Mesogean area in Europe and North Africa as well as from Cretaceous oil-bearing basins in China. Charophytes are clear indicators of supratidal environments and the abundant remains at Junction suggest a positive structural feature in this part of central Texas that might have been either an island or directly connected to the Llano Uplift.

It has long been considered that all monograptids have theca 1 originating from a primary porus in the sicula (i.e., sinus and lacuna stages; Bulman, 1970). The major basis for this assumption has been studies of Late Silurian monograptid species such as Saetograptus chimaera (Barrande), Pristiograptus bohemicus (Barrande), and Pristiograptus dubius (Suess) (e.g., Eisenack, 1942; Walker, 1953; Urbanek, 1958). That all monograptids possessed this type of development was not questioned due to the lack of well-preserved, early monograptid specimens clearly showing the sicula–theca 1 relationship. Hutt et al. (1970) described Monograptus gregarius Lapworth, from the gregarius Zone, as having theca 1 originating through a primary porus (Hutt et al., 1970; Rickards and Hutt, 1970, referred to this as a “primary notch” although, according to Bulman, 1970, p. V11, the notch corresponds only to the sinus stage). Their figures of these specimens, however, do not unequivocally confirm its presence (Hutt et al., 1970, p. 14, Pl. 3, figs. 65, 67). Rickards and Hutt (1970) alluded to the possible presence of a primary porus in Atavograptus ceryx (Rickards and Hutt) from the persculptus Zone, but could not determine its existence with certainty. Mitchell (1987) was the first to question the presence of this mode of development of theca 1 in relation to the origin of the monograptids. He proposed, however, that the development of the fully uniserial rhabdosome was coincident with a change in both the sicular structure (the sinus and lacuna stages) and the early ontogeny of theca 1. He suggested that the sinus and lacuna stages represented a homologue of the hooded foramen seen in the th 11 protheca of some Pattern H species, from which th 12 emerges and that, in the uniserial monograptids, this feature is accelerated in the astogenetic sequence, appearing in the metasicular ontogeny rather than that of the first theca. He pointed out that this hypothesis could only be tested once suitable, isolated specimens of earliest monograptids could be studied to see if the sinus and lacuna stages were, indeed, coincident with the achievement of a fully uniserial rhabdosome. New evidence from isolated, early monograptid material allows us to test Mitchell's theory on monograptid origin.