In many species of lower Paleozoic trepostomes (Bryozoa; class Stenolaemata) transverse partitions called skeletal diaphragms differentiated feeding from non-feeding regions of colonies. It has been thought that each diaphragm floored the living chamber of a feeding polypide. However, analysis of skeletal growth patterns has shown that many diaphragms were too close to colony surfaces or too closely spaced in ontogenetic sequences to have accommodated feeding polypides at any given life horizon. Apparently colonies were capable of maintenance and even robust growth with reduced numbers of active polypides, an interpretation supported by comparison with living stenolaemates.

A synthesis of the inferred functions of colonies of the extinct trepostomes with post-Triassic fossil and living stenolaemates suggests that walls of trepostome autozooids grew continuously outward so that living chambers starting from their basal diaphragms ranged from shallow to full-sized on colony surfaces. Under-sized polypides apparently grew with their under-sized living chambers and fed as they regenerated to full size, as in living stenolaemates. Actively feeding colony surfaces included autozooids either having polypides at similar or different stages of polypide regeneration, or fully regenerated. Nonfeeding colony surfaces included autozooids either having degenerated polypides, autozooids with diaphragms too closely spaced to skeletal apertures to have housed polypides, or possibly, autozooids that stopped skeletal growth in proximal regions of some large colonies.

Linguliform brachiopods were recovered from the Upper Cambrian Downes Point Member (lower Sunwaptan) and from the Middle Ordovician Factory Cove Member (Arenig) of the Shallow Bay Formation, Cow Head Group, of western Newfoundland. These rocks are a series of Middle Cambrian to Middle Ordovician conglomerates, lime mudstones, and shales that formed a sediment apron at the base of the lower Paleozoic continental slope of Laurentia. The linguliform brachiopod fauna consists of sixteen species assigned to twelve genera. Three new species are described: Picnotreta lophocracenta, Neotreta humberensis, and Siphonotretella parvaducta.

Although a number of brachiopod genera have been defined mainly from their internal structures, the fixity of those structures has rarely been investigated. Variability of the rather simple loops of two New Caledonian species of the Recent genus Stenosarina (Terebratulida), one species having a variant with endemic morphology, provides insight into the relationship between the two species. Procrustes methods based on landmarks are used. Intra-population variability is found to be of the same order of magnitude as inter-population variability. Moreover, the morphological distance between the endemic variant and the other specimens is greater than the distance between the two species of Stenosarina. The study also identifies a morphocline between the three forms of Stenosarina under study.

A small fauna of 11 species belonging to 10 genera of Permian Brachiopoda from the lower part of the Qubuerga Formation outcropping near Shengmi village in the Qomolangma region of southern Xizang (Tibet) is figured and new taxa are described. New taxa are Quinquenella semiglobosa and Costatumulus shengmiensis. The fauna is most likely of Wuchiapingian (Djhulfian) age as indicated by the majority of the brachiopod species.

Gastropods that occur in the Anomalorthis brachiopod zone in the Spring Inlet Member of the Table Point Formation and in the Orthidiella brachiopod zone of the Shallow Bay Formation of the Cow Head Group are documented. Gastropods from western Newfoundland comprise part of the Toquima-Table Head fauna, and six of the seven genera described here are also found in Whiterockian strata of Nevada. Four species assigned to Monitorella Rohr, 1994, Maclurites Le Sueur, 1818, and Malayaspira Kobayashi, 1958, originally described by E. Billings in 1865 from Middle Ordovician (Whiterockian) strata of Newfoundland are revised. Five species of Helicotoma Salter, 1859, Malayaspira Kobayashi, 1958; Lytospira Koken, 1896; Rossospira Rohr, 1994; and Pachystrophia Perner, 1903, not previously reported from Newfoundland are also described. The probable opercula of Monitorella crenulata (Billings, 1865), and Maclurites emmonsi (Billings, 1865), are also illustrated for the first time.

This paper presents a review of Cretaceous to Eocene genera and species of the Cantharus group of the buccinoidean neogastropod subfamily Pisaniinae, the description of two new genera and one new species, and a nonphylogenetic discussion of character evolution in this group. The new genus Ickarus is introduced for Tritonidea ickei Martin, 1914, from the Nanggulan beds (middle Eocene) of Java, Indonesia. Editharus (type species: Fusus polygonus Lamarck, 1803, middle Eocene of the Paris Basin, France) is a new genus with seven to nine species ranging from the early to late Eocene of Europe. Editharus is unusual in having a labral tooth formed at the angular junction between the adapical and abapical sectors of the outer lip. Editharus angulilabris from the Marinesian (early late Eocene) is a new species from the Paris Basin closely related to E. polygonus. The incidence and expression of several characters has sharply increased in the Cantharus group from the Paleogene to the Neogene. These characters include the presence of lirae (spiral ridges) on the inner side of the outer lip, the presence of a parietal tooth at the adapical end of the inner lip, and determinate growth (as inferred from a unique adult varix). These trends are also exhibited by other Cenozoic gastropod clades.

Schimperella acanthocercus, a new species of lophogastrid crustacean, is described from the Triassic of southwest China. This species is very similar to modern forms as well as the rare fossil Lophogastrida, known to date only from the Jurassic and Triassic. The sister “mysidacean” group to the Lophogastrida, the Mysida, are also rare in the fossil record; they too demonstrate remarkable similarities to living forms, suggesting that the extant “mysidaceans” had achieved “stable body plans” relatively early in their history, certainly by the Jurassic and Triassic. The third “mysidacean” group, the Pygocephalomorpha, have a considerably more extensive fossil record and are thus better understood. While “mysidaceans” are relatively rare in the fossil record, enough is known to suggest some possible biogeographic and evolutionary relationships.

More than thirty complete specimens of Carcineretes planetarius Vega, Feldmann, Ocampo, and Pope, 1997, a member of the extinct decapod family Carcineretidae, have been collected from the upper part of the Ocozocuautla Formation in Chiapas, southeast Mexico. Stratigraphic occurrences of Carcineretes in the Caribbean Province suggest that this crab should be regarded as an index fossil for the early Maastrichtian. Six samples of this species may represent individuals that died during molting. The sudden disappearance of this family at the end of the Maastrichtian and its restricted paleobiogeographic distribution in the vicinity of the impact site suggest that the Carcineretidae may have been affected by the Chicxulub impact. Other decapod specimens collected from the same localities were assigned to the Xanthidae; Parazanthopsis meyapaquensis new genus and species, and Megaxantho zoque, new genus and species, are described. They constitute the second and third reports of Cretaceous xanthid crabs from Mexico. A lagoonal paleoenvironment is suggested, based on associated fauna and flora. Occurrences of index species of benthic and planktic foraminifera along with that of diagnostic rudist species confirm an early Maastrichtian age.

Distinguishing among members of the Hexapodidae Miers, 1886, the Asthenognathinae Stimpson, 1858, and the Chasmocarcininae Serène, 1964, is difficult in fossil specimens that lack preserved pereiopods or sterna. Members of the Hexapodidae are easily identified if sterna and pereiopods are present, because possession of four pairs of pereiopods and seven exposed sternites is diagnostic for the family. Several features of the dorsal carapace are useful in differentiating among genera assigned to that family and other subfamilies belonging to the Goneplacidae and Pinnotheridae; however, dorsal carapace characters are less useful in assigning taxa at the family or subfamily level. A key to the taxa discussed herein permits generic differentiation based upon the relative dimensions of the carapace, the shape and size of the orbits, the shape and size of the rostrum, carapace ornamentation, and the degree of fusion of abdominal somites in males.

A new species of Palaeopinnixa Via, 1966, Palaeopinnixa rotundus, is described from the Eocene Coaledo Formation of Oregon, USA. A new hexapodid genus and species, Globihexapus paxillus, is recognized from the Miocene Astoria Formation of Washington, USA. Prepaeduma decapoda Morris and Collins, 1991, is referred to Hexapus de Haan, 1833. Viapinnixa new genus has been erected to accommodate material previously assigned to Pinnixa (Palaeopinnixa) nodosa Collins and Rasmussen, 1992, and Orthakrolophos has been named to accommodate three species of Palaeograpsus Bittner, 1875. Asthenognathus urretae new species is described from the middle Eocene Centinela Formation of southern Argentina.

The morphology of the eyes of the olenid trilobite Jujuyaspis keideli Kobayashi, 1936, is described and illustrated. Studied specimens come from Early Tremadocian pyritiferous black shales of the Casa Colorada Formation (= Purmamarca shales) at Purmamarca, Jujuy Province, northwestern Argentina. The eyes are holochroal and proportionately large relative to the overall size of cephalon. They are always found attached to the librigena, showing no preserved lenses, only molds of their surfaces. Their molds demonstrate that lenses were numerous, biconvex, hexagonal in outline and arranged in an hexagonal close-packing system. The eye curvature and the disposition of the facets covering all the visual surface indicate that Jujuyaspis keideli Kobayashi had a visual field wider than that of most benthic olenids. The pattern of lens arrangement and the poorly developed peripheral zone support pelturine affinities for the species.

Stratocladistics combines morphological and stratigraphic data in a parsimony-based analysis of evolutionary relationships. We use stratocladistics here to provide an overview of the phylogeny of the extinct echinoderm class Blastoidea. Both cladistic and stratocladistic methods evaluate alternative phylogenies by comparing the number of ad hoc hypotheses needed to reconcile each alternative to observed data. Minimization of ad hoc hypotheses selects the phylogeny best supported by data and enables phylogenetic analyses to incorporate data from different sources. Cladistics treats ad hoc hypotheses of homoplasy, whereas stratocladistics additionally considers ad hoc hypotheses of differential preservation probability of lineages in the stratigraphic record.

The blastoid phylogeny derived using stratocladistics is more resolved than hypotheses selected by cladistics. Although the morphological characters are relatively homoplasious, in this instance the stratigraphic ordering of fossils provides both structure and altered polarity for the stratocladistic hypothesis. The stratocladistic phylogeny supports previous paleontological conclusions of convergence among blastoid lineages and facilitates evaluation of specific hypotheses of character transformation that are integral to recent systematic revisions. Additionally, consideration of temporal data makes some hypotheses of ancestor-descendant relationships more parsimonious than hypotheses of derivation from a common ancestor. The ability to recognize sequential members within single lineages allows more accurate estimation of faunal diversities and more specific reconstruction of evolutionary histories. Chief among possible confounding factors in stratocladistics are instances where preservation potential shows significant geographic variation, although problems of preservation are more tractable than the difficulties homoplasy presents for cladistic analysis.

Three flexible crinoids occur in the Upper Ordovician Maquoketa Formation of Illinois, Iowa, and Minnesota: Protaxocrinus girvanensis Ramsbottom, 1961, Clidochirus anebos new species, and Proanisocrinus oswegoensis (Miller and Gurley, 1894). Protaxocrinus girvanensis is also found in the Upper Ordovician of Scotland which indicates that the ocean was narrow enough to allow at least one crinoid species to cross the barrier. The Upper Ordovician of North America and Scotland also share many common crinoid genera. Both phenetic and cladistic methods result in similar phylogenies of flexible crinoids. Protaxocrinus was derived from a cupulocrinid ancestor during the Middle Ordovician. Clidochirus evolved from Protaxocrinus or its ancestral stock prior to the Richmondian of the Late Ordovician. The Richmondian Proanisocrinus and later anisocrinids are most closely related to Clidochirus or its immediate predecessor. Thus, three major lineages of flexible crinoids, Protaxocrinus (taxocrinid group), Clidochirus (icthyocrinid), and Proanisocrinus (anisocrinids and homalocrinids), appeared during the Ordovician. Despite their rarity during the Ordovician, all three flexible lineages survived the Latest Ordovician extinction, whereas their more abundant and successful cupulocrinid ancestors were eliminated.

Two new species of primitive cladid crinoids, Costalocrinus ibericus and C. thymos, from the Lower Devonian (Emsian) of northwest Spain, provide important information on the evolution of the Costalocrinus-Barycrinus lineage during the Devonian and Mississippian. Costalocrinus ibericus n. sp. is morphologically similar to Barycrinus rhombiferus (Owen and Shumard, 1852) from the Mississippian, except for the characters of the anal X plate and degree of calcification of the anal sac. These two species are separated by approximately 55 m.y. and provide evidence of slow morphologic change, or phenotypic bradytely, in this lineage. Such slow morphologic change is consistent with the previous interpretation of Barycrinus as an ecologic generalist. Very few other genera of Paleozoic crinoids evolved at such a slow rate. Costalocrinus thymos n. sp. is more typical of other species of Costalocrinus from the Middle Devonian and Lower Mississippian. Phylogenetic analysis suggests the ancestral lineage of the Mississippian genus Barycrinus evolved from Costalocrinus near the base of its radiation in the Early Devonian (Emsian).

Field work conducted in the northeastern Aral Sea Region, southwestern Kazakhstan has produced a large number of vertebrates from late Cretaceous and early Tertiary sediments. Included among these vertebrates are sharks, bony fishes, amphibians, turtles, lizards, crocodiles, and dinosaurs. This fauna comes from three formations, the Turonian-Coniacian Zhirkindek, the Santonian-Campanian Bostobe, and the early Tertiary Akzhar formations. In this paper we describe the microvertebrate fauna. The Akzhar fauna consists only of marine sharks, one hexanchiform species (Notidanodon cf. loozi) and four lamniform species (Carcharias teretidens, Striatolamia striata, Otodus obliquus var. minor, and Palaeocarcharodon orientalis). These suggest a Paleocene age, most likely Selandian or earliest Thanetian. In addition to previously described components, the Bostobe fauna now includes a discoglossid frog and the lizard Slavoia cf. darevskii. This is the first Mesozoic record of each in Kazakhstan and the latest record anywhere of the latter. The Zhirkindek fauna is now known to include a varanid lizard.

A partial skeleton of Daspletosaurus sp. from the Late Cretaceous (Campanian) Two Medicine Formation of western Montana preserves the first gut contents reported for a tyrannosaurid. Associated remains found with this skeleton consist of acidetched vertebrae and a fragmentary dentary from juvenile hadrosaur dinosaurs. Hadrosaur bonebed data and comparisons of hadrosaur and tyrannosaurid limb proportions suggest that juvenile hadrosaurs represented both an abundant and accessible food source. The surface corrosion exhibited by the hadrosaur elements matches that produced by stomach acids and digestive enzymes in a wide variety of living vertebrates. Based upon these and other gut contents, and also upon tooth-marked bone studies, it appears that Daspletosaurus and most theropods ingested and digested prey in a manner similar to that of extant archosaurs (crocodilians and birds), employing a two-part stomach with an enzyme-producing proventriculus followed by a thick-walled muscular gizzard. This two-part stomach appears to be an archosaur synapomorphy.

A new genus and species of tapiromorph, Karagalax mamikhelensis, is described from the Eocene Mami Khel Formation of northwest Pakistan. The new species is known from adult and juvenile dentitions, juvenile skulls, and partial postcrania. It is the most primitive perissodactyl yet reported from Indo-Pakistan. The morphology of its lophodont molars indicates that Karagalax is a tapiromorph, and it is here included in the primitive family Isectolophidae. Karagalax is more derived (more lophodont) than North American isectolophids Systemodon and Cardiolophus or the Asian early Eocene Orientolophus and Homogalax wutuensis, and more primitive (less lophodont) than North American Homogalax and Isectolophus. It is distinct from the poorly known and enigmatic Indian isectolophid Sastrilophus. Karagalax lacks any derived features of the Deperetellidae, Helaletidae or Lophialetidae, including Kalakotia, a primitive lophialetid from the middle Eocene of northwest India. The partial postcrania of Karagalax, which include fragmentary humeri, femora, ulnae, tibiae and metapodials, show a combination of primitive and derived features and suggest that it was more cursorial than other basal tapiromorphs for which postcrania are known.

A provisional analysis of the phylogenetic positions of Karagalax and Kalakotia supports the hypothesis that primitive perissodactyls dispersed to Indo-Pakistan, most probably by way of continental Asia. The evolutionary position of Karagalax is consistent with an early Eocene age for H-GSP Locality 300, as argued previously on the basis of other mammals.

Due to similarities in size as well as in morphology between the type materials of both species, synonymy of Atlantoxerus idubedensis Cuenca Bescós, 1988, with the species A. blacki (de Bruijn, 1967) is proposed. New and previously described material of the genus Atlanioxerus from the Aragonian type area in Spain are assigned to a single species, A. blacki, on the basis of metrical and morphological analyses. An emended diagnosis for A. blacki is proposed in order to include the observed variability. This species is characterized by its high morphological variability, tendency towards reduction in some relative dental proportions, and tending to increase in size rapidly.

Diverse assemblages of silicified microfossils have been detected in lenses of black chert within peritidal carbonates of the Neoproterozoic (Upper Riphean) Shorikha and Burovaya formations, Turukhansk Uplift, northeastern Siberia. These microbiotas are represented by 19 species of simple filamentous and coccoidal microfossils, multicellular trichomes, and thick-enveloped sphaeromorphic and acanthomorphic acritarchs. Microfossils include both prokaryotic (possibly cyanobacterial) and eukaryotic (mainly phytoplanktonic) microorganisms. The eukaryotes in these formations are relatively diverse—the result of an explosive radiation near the Meso-Neoproterozoic boundary. The discovery of abundant phytoplanktonic microorganisms in the Shorikha and Burovaya cherts increases the biostratigraphical potential of Proterozoic silicified microbiotas and fills a gap in the paleontological record of the Turukhansk Uplift, a potential candidate for the stratotype of the Meso-Neoproterozoic boundary. The affinities of the formally described taxa are postulated as follows: Oscillatoriaceae: Eomicrocoleus crassus Horodyski and Donaldson, 1980; Oscillatoriopsis obtusa Schopf and Blacic, 1971; O. media Mendelson and Schopf, 1982; Oscillatoriaceae or Nostocaceae: Siphonophycus robustum (Schopf, 1968); S. typicum (Hermann, 1974); S. solidum (Golub, 1979); Nostocaceae or Stigonemataceae: Archaeoellipsoides minor (Golovenoc and Belova, 1984); Chroococcaceae: Gloeodiniopsis lamellosa Schopf, 1968, Eosynechococcus grandis Hofmann, 1976; Incertae sedis: Scissilisphaera gradata Green, Knoll and Swett, 1989; Myxococcoides minor Schopf, 1968; M. inornata Schopf, 1968; M. stragulescens Green, Knoll, and Swett, 1989; Myxococcoides sp.; Pterospermopsimorpha? sp.; Shorikhosphaeridium knolli new genus and species; Leiosphaeridia jacutica (Timofeev); problematic ellipsoidal forms; and problematic spiny forms.

Early Permian (late Leonardian Series) plant assemblages from King, Knox, and Stonewall Counties of North-Central Texas are dominated by seed plants, some apparently congeneric with taxa heretofore known only from the Late Permian or the Mesozoic. Conifers are the dominant elements, including one or more species of Ullmannia, Pseudovoltzia liebeana, both known from the Late Permian Zechstein flora of Germany and England, Podozamites sp., characteristic of the Mesozoic, and Walchia sp., abundant in Early Permian floras. Locally common are Taeniopteris cf. eckardtii, a Zechstein species, an unidentified plant represented by pinnulelike laminae with fine parallel veins, similar to pinnules of some Mesozoic cycads, and calamite stems. Rarely encountered are leaf fragments of the Paleozoic ginkgophyte Dicranophyllum, flabellate ginkgophyte leaves, leaves with a broad midvein and narrow, fimbriate lamina, and Wattia, typical of the Early Permian. Associated with these foliar remains are ovulate reproductive structures including the presumed cycad megasporophyll Dioonitocarpidium, known only from the Mesozoic, a voltzialean cone scale similar to Swedenborgia, and a variety of seeds, some remarkably similar to Agathis, of Cretaceous age. The assemblage includes only rare scraps of foliage and seeds possibly attributable to the pteridophyllous elements (gigantopterids, callipterids, and ferns) that dominate the Permian. The fossil plants occur in multistorey, fining-upwards, tidal-channel deposits that also include pelecypods and fragmentary palaeoniscoid fish. The occurrence of derived lineages in xeric habitats during the Early Permian indicates that some supposed Mesozoic groups actually preceded and survived the end-Permian extinction, reappearing in basinal lowlands during the mid-Mesozoic.

Fossilized opercula are uncommon in Paleozoic rocks, and shells with the operculum in place are rare. A single specimen with the operculum in place was discovered by P. Slehofer in a concretion in the Ordovician Zahorany Formation of the Prague Basin. Formerly known as Trochonema excavatum Barrande in Perner, 1903, the species is the basis of the new genus Slehoferia. Perner (1903) reported the shell of the same species from two localities, and additional specimens without the operculum are in the collections of the National Museum and Czech Geological Survey. Studied material is deposited in the paleontological collection of the Czech Geological Survey, Prague.