Protamphisopus wianamattensis (Chilton, 1918) from the Middle Triassic (Anisian) Ashfield Shale in the Sydney Basin, Australia, is the earliest-known freshwater representative of the basal isopod suborder Phreatoicidea. In contrast, the late Paleozoic Palaeophreatoicidae species, which are morphologically distinct from extant families, are found in marine or estuarine facies. Comparison of Protamphisopus wianamattensis with living Phreatoicidea permits the external morphology of the fossils to be reconstructed and the species to be coded for cladistic analysis using a revised and expanded character set developed for living phreatoicideans. In resulting parsimonious trees as well as immediately suboptimal trees, Protamphisopus is nested within clades related to the family Amphisopodidae. Although not included in the analysis, the Late Permian Protamphisopus reichelti Malzahn (in Glaessner and Malzahn, 1962) appears to be a member of the Palaeophreatoicidae, rather than among the crown group of the Phreatoicidea. Therefore, a minimum age of Middle Triassic can be assigned to the basal branches within the phreatoicid crown group. The minimum age for the colonisation of fresh water by the suborder is also established although, given the advanced position of Protamphisopus wianamattensis in the cladograms, the habitat shift may have occurred earlier. The biogeographic distribution of extant Phreatoicidea on fragments of Gondwana is consistent with early Mesozoic origins for the major clades of this isopod suborder.

The Early Oligocene to Recent genus Lirabuccinum Vermeij, 1991, is a North Pacific clade of rocky-bottom predatory buccinid gastropods. A re-examination of all available material from eastern Asia and comparison of this material with western American species leads us to recognize four northwestern Pacific species: L. fuscolabiatum (Smith, 1875) from the Pliocene to Recent; L. japonicum (Yokoyama, 1926) from the Pliocene and Early Pleistocene; L. branneri (Clark and Arnold, 1923) from the early Middle Miocene, also known from the Oligocene in the eastern Pacific; and Lirabuccinum sp. from the late Middle Miocene. The genus originated in the eastern Pacific and subsequently spread to the western Pacific by late Early Miocene to early Middle Miocene time. Lirabuccinum exemplifies a common pattern among rocky-bottom North Pacific gastropods in that the early species have a thick, internally strongly ribbed or denticulate outer lip. As they adapted to the colder boreal realm during the Pliocene and Pleistocene, Lirabuccinum and such other clades as Nucella, Ceratostoma, and Ocinebrellus (all Muricidae) evolved thinner, less heavily reinforced outer lips.

New heterostrophic gastropods are reported from the lowermost part of the Dayie Formation (Early Triassic, Leping, Jiangxi province, China). A new genus Jiangxispira (Streptacididae) is described. Jiangxispira yangouensis new genus and new species has an almost discoidal, heterostrophic protoconch that is typical of the largely Paleozoic Streptacididae, yet the teleoconch resembles that of certain Mesozoic opisthobranchs belonging to the Superfamily Cylindrobullinoidea. This character combination in Jiangxispira may indicate a phylogenetic link between the Paleozoic Streptacididae (Allogastropoda) and the Mesozoic Cylindrobullinoidea (Opisthobranchia). Small opisthobranchs form an important component of Early Triassic gastropod faunas. The opisthobranchs seemingly benefited from selective processes operating during the Permo-Triassic mass extinction and the reorganization of gastropod faunas during the subsequent recovery period.

Myophorellid bivalves (Trigonioida, Myophorellacea) with conspicuously tuberculate shells are abundant in Lower Cretaceous rocks of the Neuquén Basin represented by the Gondwanian genus Steinmanella Crickmay, 1930. Publications concerning Neuquén trigonioids deal only with taxonomy, and until now the sedimentary environments of the Steinmanella bearing facies have not been interpreted. The present study analyzes morphology, taxonomy, stratigraphy, and paleobiology of Steinmanella species collected from five sections of the Lower Member of the Agrio Formation, including the type locality. Two species are differentiated: Steinmanella pehuenmapuensis (Leanza, 1998) from the lower part of the member (Pseudofavrella angulatiformis Zone) and Steinmanella transitoria (Steinmann, 1881) from the middle and upper part of the member (Holcoptychites neuquensis, Hoplitocrioceras gentilii, and Weavericeras vacaensis Zones).

Specimens of both species have been recorded in intermediate to high-energy shoreface and low-energy offshore deposits. The inferred paleoecologic model is that Steinmanella lived semi-infaunally and burrowed on sandy substrates in the shoreface and on muddy substrates in the offshore. Colonization of low-energy subenvironments in the offshore probably occurred during increased sea-floor oxygenation and reduced net sedimentation or brief omission periods.

Study of the shell features of Givetian and Frasnian spiriferid brachiopods attributed to the genus Cyrtospirifer shows that the type species C. verneuili has micro-ornament consisting of fine concentric growth lines, radial capillae, with microspines arising from some capillae, spine bases appear to extend into the primary shell layer. Its dorsal interior features a pseudoseptum supporting the cardinalia. Micro-ornament of Cyrtospirifer varies widely and is a useful criterion for characterization of species of the genus. Most Frasnian species retained in the genus have micropustulate shells. Two late Givetian and Frasnian phylogenetic species groups of Cyrtospirifer are recognized based on similarities of shell form and external and internal shell features. Species of the verneuilisyringothyriformis group have transverse alate shells, and are the most abundant and widespread group in Frasnian deposits worldwide. The verneuiliformis group includes the oldest known species of Cyrtospirifer with narrow hinges and more inflated ventral valves where shell width is close to or equal to length. The oldest Cyrtospirifer originated in western Europe during the late Givetian, and subsequently migrated at different times during the Frasnian into other shelf areas of Eurasia, North America and China. The initial migration of Cyrtospirifer into tropical and subtropical shelf settings in North America coincided with the middle Frasnian eustatic sea level rise of Devonian Transgressive-Regressive (T-R) cycle IIc of Johnson and others. A second late Frasnian dispersal from western Canada to subtropical carbonate and clastic shelves in the southwestern and central U.S. coincided with the initial sea level rise of T-R cycle IId of Johnson and others. The Frasnian species Cyrtospirifer glaucus Crickmay, 1952a (middle Frasnian of western Canada) is the type species for Regelia Crickmay, 1952b, and is considered a valid genus, and is not a synonym of C. chemungensis (Conrad, 1842) as previously interpreted by some authors. Regelia differs from Cyrtospirifer in the absence of a delthyrial plate, complete in-filling of the delthyrial cavity by secondary shell material, its simpler rod-like teeth, and its fewer medial sinal shell plications. Species of Regelia are restricted to the middle to late Frasnian of North America.

The Late Carboniferous bransoniid conocardioidean Apotocardium lanterna (Branson, 1965) had an entirely aragonitic shell with a finely prismatic outer shell layer, a predominantly crossed lamellar to complex crossed lamellar middle shell layer, and an “inner” shell layer of finely textured porcelaneous and/or matted structure. This “inner” layer is probably homologous with the inner part of the middle shell layer and the inner layer sensu stricto of bivalved molluscs. Shell morphological and microstructural convergences between conocardioids and living heart cockles suggest that at least some conocardioids may have farmed algal endosymbionts in their posterior mantle margins. This symbiosis may have helped conocardioids compete with the biomechanically more efficient bivalves during the latter part of the Paleozoic.

A new genus Ibergirhynchia, a member of the rhynchonellide superfamily Dimerelloidea, is described for the species Terebratula contraria Roemer, 1850, from Early Carboniferous deposits of the Harz Mountains, Germany. Ibergirhynchia contraria is from a monospecific brachiopod limestone that formed on top of the drowned Devonian Iberg Reef which persisted as a seamount during Famennian and Early Carboniferous times. Ibergirhynchia contraria is considered a cold seep-related brachiopod based on this locality. Such seep associations have been observed for Mesozoic representatives of the rhynchonellide superfamily Dimerelloidea. Ibergirhynchia is considered the first Paleozoic representative of the family Rhynchonellinidae. Ibergirhynchia resembles Dzieduszyckia externally and may be derived from this dimerelloid.

We used 24 fossil and Recent species to construct character states of both composite and exemplar taxa for phylogenetic analyses of Neogene genera and subgenera of the Corbulidae from tropical America. All characters were conchologic and two matrices, which differed in the manner that commarginal-rib characters were coded, were analyzed using branch and bound searches and maximum parsimony. Character polarity was determined using Corbula sensu strictu as an outgroup. These analyses produced a limited number of robust and well-resolved cladograms that require only one ghost lineage. Such stable results indicate a high level of congruency among characters, and demonstrate that conchologic data sets can yield highly resolved cladograms.

Tropical American corbulids are not monophyletic, and include two major clades. Crown groups within these clades are endemic, and all genera endemic to tropical America first appear in the Miocene. In fact, generic diversity and body size peak in the upper Miocene of the Caribbean/western Atlantic. Range restrictions and extinctions of large-bodied genera from both corbulid clades contribute to a post-Miocene decline in body size in this region. The eastern Pacific does not experience a similar decline in diversity and body size. Diversity and morphologic trends in Caribbean corbulids coincide with regional environmental changes, in particular decreases in seasonality and productivity. Except for the extinction of Bothrocorbula, however, corbulid extinctions apparently predate faunal turnover reported for other molluscs.

Associated with these extinctions, we found evidence of geographic range restriction, but not range shifts, in corbulid genera, indicating that the geologic development of environmental refugia contributed more to survival than eurytopy. Large-bodied genera of the southern Caribbean Gatunian Province (Tenuicorbula, Panamicorbula, and Hexacorbula) became restricted to the eastern Pacific. Range restriction to this high productivity refugium (i.e., paciphilic genera), rather than origination of new taxa, produced several corbulid genera now endemic to the region. Large-bodied genera from the Caloosahatchian Province of the southeastern U.S. (Bothrocorbula and Bicorbula), however, underwent global extinction. These subtropical and warm temperate taxa are presumably more eurytopic than their tropical counterparts, but do not exhibit range shifts in response to Neogene environmental change.

Small, silicified rostroconchs are present in the late Wolfcampian Bird Spring Formation in Nevada. Hadropipetta nevadaensis new species, Minycardita sectilis new genus and species, and Baiosoma sp. are described.

Parazophocrinus callosus Strimple, 1963, is redescribed as a cladid crinoid belonging to the Codiacrinidae. Parazophocrinus is a reasonably large cladid crinoid that is composed primarily of basal plates, radial plates, and oral plates; arms are absent; and the anal opening is along the side of the aboral cup. The radial plates are hypertrophied laterally, producing a disc-shaped aboral cup, and this very unusual crinoid is considered to be neotenic. Presumably, feeding in Parazophocrinus occurred only with tube feet projected through opened oral plates or from epidermal nutrient uptake. Typical codiacrinids may lack arms, may have the anal opening from the side of the aboral cup, and commonly have prominent oral plates; but in contrast to Parazophocrinus, they are small to very small in size. This small size and arrested development is considered progenetic.

Parazophocrinus is the second oldest genus in the Codiacrinidae. Apparently, when developmental controls broke down during the early evolution of this family, both neotenic and progenetic crinoids evolved. However, ultimately, the Parazophocrinus morphology, a large crinoid lacking arms, was not successful through time. Thus, although more than one heterochronic pathway was possible, functional and ecologic constraints determined which developmental pathway would have long-term success.

Three new genera and six new species of shallow-marine gastropods are named from Upper Cretaceous strata found mainly in California. The trochids Cidarina cretacea new species and Cidarina beta new species, the ficid Bulbificopsis garza new genus and new species, and the cancellariid Mataxa arida new species are from the Maastrichtian part of the Moreno Formation of north-central California. This is the earliest record of Cidarina, whose previous chronologic range was middle Eocene to Recent. Bulbificopsis is the first record of a Cretaceous ficid from the Pacific slope of North America, and Mataxa was previously known only from Upper Cretaceous strata in the southeastern United States and northeastern Brazil. The buccinid Eripachya jalama new species and the fasciolariid Calkota daileyi new genus and new species are from the lower upper Campanian Jalama Formation in southern California. Calkota is also recognized herein as occurring in upper Maastrichtian strata of North Dakota and South Dakota. The new melongenid genus, Pentzia, established for Fulgur hilgardi White, 1889, is from Campanian strata throughout California; middle Campanian strata on Sucia Island, Washington; and upper Campanian to lower Maastrichtian strata in northern Baja California, Mexico.

A new Burgess Shale-type soft-bodied fauna crossing the Lower-Middle Cambrian boundary in the Comet Shale Member of the Pioche Formation in Lincoln County, Nevada, contains common remains of soft-bodied ecdysozoan taxa. These fossils provide important new information about the nature and variety of Cambrian soft-bodied organisms. Arthropod taxa include one species of Canadaspis Novozhilov in Orlov, 1960, one species of ?Perspicaris Briggs, 1977, three species of Tuzoia Walcott, 1912, and at least two species of Anomalocaris Whiteaves, 1892. A priapulid referable to Ottoia Walcott, 1911a, was also recovered. A comprehensive review of Tuzoia is given. Some specimens from Early Cambrian sections are replaced by hematite, resulting in iron staining similar to that in such other Early Cambrian soft-bodied faunas as the Kinzers Formation in Pennsylvania. Some taxa in the Comet Shale, and in other Early and Middle Cambrian soft-bodied faunas, have prodigious geographic ranges that spanned much of Laurentia and even other Cambrian cratons. Moreover, these taxa ranged across the Early-Middle Cambrian boundary relatively unscathed. This is in contrast to many trilobite taxa that had narrow geographic ranges in the Early Cambrian and high levels of extinction at the Early-Middle Cambrian boundary.

A new genus, Anomalosaepia, and four new species, A. alleni, A. mariettani, A. vernei, and A. andreanae (Sepiida: Belosaepidae) from the Castle Hayne Limestone of southeastern North Carolina are described. Belosaepia jeletzkyi from the Cook Mountain Formation of Louisiana is assigned to Anomalosaepia. All new and referred species differ from Belosaepia in having strongly laterally curved ventral plates, guard-like sheaths without external rugosities, and spine tips with a slit-like aperture.

Emphereaster missouriensis new genus and species, Ambigaster, new genus, and Delicaster, new genus are assigned to the Carboniferous asteroid family Neopalaeasteridae Schuchert. The neopalaeasterids are similar to but separable from the Carboniferous Monasteridae, Calliasterellidae, and Fandasteridae, n. fam., in ambulacral and other characters. The several families indicate that late Paleozoic asteroids were diverse although poorly documented.

Similarities between late Paleozoic stem-group and post-Paleozoic crown-group asteroids allow argumentation on ossicular homologies. In species with only a single row of arm marginals, an earlier suggestion that certain disk ossicles are superomarginals is rejected. Enlarged proximal adambulacrals fill space on the actinal surface whereas actinal ossicles, generally lacking in Paleozoic asteroids, provide the space-filling service in crown-group asteroids.

The body wall beyond the ambulacral column and accessory ossicles traditionally have been stressed in the classification of asteroids of all ages. Because of body wall homoplasies, many older taxonomic concepts do not identify monophyletic late Paleozoic clades, nor do they indicate the derivation of the crown group. Ambulacral characters in contrast are conservative through long periods of geologic time, improving phylogenetic resolution as more taxonomic data become available. Now-available ambulacral skeletal data for certain Carboniferous genera suggest membership in lineages basal to the post-Paleozoic crown group.

Emphereaster missouriensis and most neopalaeasterids are stoutly constructed suggesting a defensive mechanism against durophagous chondrichthyan fish that co-occur with the holotype of Emphereaster. Abundant sponge spicules within the disk of the holotype suggest it fed on sponges, a prey type widely exploited by living asteroids.

The ctenonotellid ostracode species Brezelina palmata (Krause, 1889) and the tetradellid species Ogmoopsis bocki (Öpik, 1935) are represented by seven and five molting stages, respectively. Both species display an association of velar and size dimorphism in the three last instars. The analysis of the juvenile morphology of O. bocki provides evidence for a close relationship with the earliest known palaeocope ostracode species Nanopsis nanella (Moberg and Segerberg, 1906). The population age structure of B. palmata in synchronous beds at two localities reveals different types of thanatocoenoses, supporting the hypothesis of a deepening gradient along the Baltic-Ladoga Klint.

Intra- and interspecific variation in the early internal shell features of ammonoids has been examined in 14 Late Cretaceous species representing four suborders on the basis of large samples from Hokkaido (Japan) and the U.S. Western Interior Province. Our observations indicate that quantitative characters such as the size of the initial chamber and ammonitella, the length of the prosiphon, and the ammonitella angle exhibit moderate variation within species. The ranges of variation partly overlap among species, indicating that these characters are not suitable for studies of the higher-level systematics of ammonoids, but may sometimes help diagnose species. In contrast, there is much less variation within species with respect to qualitative characters such as the shape of the prosiphon, the presence or absence of accessory threads of the prosiphon, the shape of the caecum, and the initial position of the siphuncle. Examination of these characters shows that they appear to be stable at the superfamily level for the Ammonitina, but variable among species in the Lytoceratina. Thus, these characters are potentially more useful for higher-level phylogenetic analysis.

Hyolith assemblages from Middle and Upper Ordovician strata in Estonia include representatives of Hyolithes Eichwald as H. gerhardi new species and H. burgessi new species, and one assigned to that genus with question. Dorsolinevitus Syssoiev is known from D. marri new species, D. dispar? (Holm, 1893) and D. textilis? (Holm, 1893); one questionable species of that genus is left in open nomenclature. Sulcavitus Syssoiev is represented by one unidentifiable species, and one incompletely preserved orthothecid constitutes the first member of that group to be recorded from Estonia. Despite the overall paucity of identifiable hyoliths from Estonia, several of the same genera are now known to be present in Estonia and Sweden, reinforcing the notion that the hyoliths of Baltica constitute a distinct biogeographic province with limited mixing of faunas from elsewhere.

Although bradoriids locally are common components of the Cambrian biota, they have been reported previously from Antarctica only from Tertiary glacial deposits. Here, we describe the bradoriid, Bicarinella evansi new genus and species, collected in situ from the upper Lower Cambrian (Botomian) of the Pensacola Mountains in East Antarctica. Bicarinella evansi n. gen and sp. is characterized by a subtriangular carapace with a well-defined marginal rim, subequal anterior and posterior lobes that are elongated into sharp ridges extending one-third the length of the carapace, and a broad dorsal node placed between the anterior and posterior lobes. The surface of the carapace exhibits three kinds of ornamentation: fine pitting, pustules, and reticulae. Several smaller carapaces with reduced ornamentation collected from the same bed are interpreted as instars of this species. Bicarinella n. gen. is assigned to the family Hipponicharionidae and appears to be closely related to Albrunnicola Martinsson, 1979, or Hipponicharion Matthew, 1886. Although strong archaeocyath faunal similarities demonstrate a close biogeographic relationship between Australia and Antarctica in the Early Cambrian, the possible sister group relationship of Bicarinella n. gen. to Hipponicharion, which is otherwise unknown from Gondwana, may suggest a separate biogeographic pathway to East Antarctica that did not involve Australia.

Fourteen species of echinoids ranging in age from early to late Eocene, including four new species, are described from Texas. New taxa include Schizaster (Schizaster) caddoensis from the Reklaw and Weches Formations (Claiborne Group, middle Eocene), Schizaster (Schizaster) stenzeli and Eupatagus texanus from the Weches Formation, and Schizaster (Paraster) susana from the Caddell Formation (Jackson Group, upper Eocene). Fibularia meyeri (Aldrich, 1921) and Fibularia alabamensis Cooke, 1959 are synonymized with Fibularia texana (Twitchell, 1915) from the Weches and Cook Mountain Formations (Claiborne Group, middle Eocene). Other reported species are Linthia hollandi Barry, 1942, from the Sabinetown Formation (Wilcox Group, lower Eocene); Gagaria sp., Protoscutella tuomeyi (Twitchell, 1915), Protoscutella mississippiensis mississippiensis (Twitchell, 1915), Maretia arguta (Clark, 1915), and Linthia? sp. from the Weches Formation; Spatangus? sp. and Eupatagus carolinensis? Clark, 1915 from the Cook Mountain Formation, and Periarchus lyelli (Conrad, 1834) from the Cook Mountain and Caddell Formations. These echinoids are sensitive indicators of depositional environment, in particular their distribution serves as a marker for stenohaline (open marine) environments and illustrates the biogeographic variability along the northeast Texas coast during the Eocene.

The Upper Albian Desmoceras species of Japan are described, based on material from the Yezo Supergroup in Hokkaido, north Japan, and from the Fujikawa Formation in Shikoku, southwest Japan. Based on comparative analysis of morphologic variation and shell growth of relevant specimens, we assign the present material to two species: Desmoceras (Desmoceras) latidorsatum (Michelin, 1838) and Desmoceras (Pseudouhligella) poronaicum Yabe, 1904. Japanese examples of the latter species have been previously referred to “Desmoceras (Pseudouhligella) dawsoni,” a Canadian species present on Queen Charlotte Islands, British Columbia, but not represented in the Japanese Islands. Desmoceras (Pseudouhligella) poronaicum is also known from British Columbia.

The subgenus Pseudouhligella presumably originated in the eastern Pacific during the Late Albian and subsequently migrated to the western Pacific during latest Albian to earliest Cenomanian time. Desmoceras (D.) latidorsatum is a Tethyan form; its presence in the Upper Albian of the North Pacific probably reflects a northward excursion of warm-water currents from the tropical region during Late Albian time.