The graptolite, Bohemicograptus bohemicus tenuis (Bouček, 1936), was collected with additional hexactinellid sponges from the Roberts Mountains Formation in the Snake Mountains of Elko County, Nevada, and dates the sponge beds as Ludlovian. To the modest fauna of hexactinellid sponges described by Rigby et al. (1991), can be added the new sponge genera and species Divaricospongia dilata and Fistellaspongia inclinata. The new species, Gabelia intermedia, is intermediate in size between the moderately fine-textured Gabelia pedunculus Rigby and Murphy, 1983, and the large Gabelia giganta Rigby et al. 1991. Additional specimens of Gabelia pedunculus were collected in association with well-preserved specimens of Gabelia fasiculata Rigby et al. 1991, which show additional skeletal and canal details. Associated coarse root tufts and patches of protosponge skeletal mesh were also discovered as part of the new collections and are described here, although not generically nor specifically identifiable.

Damage displayed by 18 of 954 relatively mature (> 35 mm diameter) specimens of Gonioloboceras goniolobum (Meek) from North American Midcontinent Upper Carboniferous sediments is interpreted to be bite marks caused by condrichthyans and other fish, particularly the symmoriid shark Symmorium reniforme. It is likely that these and other predators regularly preyed on Gonioloboceras goniolobum because all of the analyzed specimens of Gonioloboceras exhibit some evidence of unrepaired damage, including broached camerae and missing body chambers. Two new characteristics utilized with caution to detect predatory events on ammonoids are raised oval or circular pedestals on internal molds and the breakage and termination of septa in conjunction with a broken external shell. When sufficient damage to the Gonioloboceras conchs occurred during predatory attacks, the broached camerae flooded, the conch became negatively buoyant, and it sank in the vicinity of the attack. When preserved, these conchs form a variable component of an autochthonous fossil accumulation that can include numerous other cephalopod taxa, which also were probably subjected to predatory attacks. Other, but not all, ammonoid accumulations in the fossil record form similar autochthonous deposits, or even autochthonous portions of mixed deposits.

Givetian species of Chinese brachiopods previously assigned to the genus Spinatrypa or Spinatrypina reveal an internal structure characteristic of other species referred to the Eifelian genus Kerpina and the cosmopolitan Frasnian genus lowatrypa. Serial sections clarify the nature of the Middle Devonian Chinese species, which are described here as a new genus, Invertina (type species, Atrypa aspera var. sinensis Kayser, 1883). The internal structure of the Late Devonian type species of Iowatrypa, Atrypa owenensis Webster, 1921, is illustrated for the first time for comparison. These three genera, as well as three other genera, are referred to a new Devonian (Emsian-Frasnian) subfamily, the Invertininae, allocated to the family Atrypidae.

Investigation of specimens of “Terebratella” ovula Anderson, 1938 from the upper Lower Albian Upper Chickabally Member of the Budden Canyon Formation, Great Valley Group, California has allowed the examination of the species' internal structures by serial sectioning. “Terebratella” ovula Anderson is now referred to the genus Dzirulina Noutsoubidze, 1945. The stratigraphic range of the genus is extended from the Hauterivian–Aptian to the Albian. The geographic range of Dzirulina is increased from central and western Europe, the Caucasus and Georgia of eastern Europe, and northern Zululand, Africa to now include northern California, North America. This represents an additional record of an Early Cretaceous brachiopod genus with a low-latitude, transatlantic distribution, most probably related to dispersal across the opening Central Atlantic Ocean.

Two rhabdomesonid cryptostome bryozoans, Rhabdomeson progracile n. sp. and Rhabdomeson rhombiferum (Phillips, 1836), are described from the Lower Carboniferous of the British Isles. A revised familial diagnosis of Rhabdomesidae Vine, 1884, and a revised generic diagnosis of Rhabdomeson Young and Young, 1874, are presented. Taxonomic complications relating to the type species of the genus, which date from 1844, are discussed, and it is suggested that a new type species is required.

Uninterrupted, ~800 m thick, Ashgill through Llandovery carbonate strata from Anticosti Island (eastern Canada) reveal five new brachiopod genera, enhancing present knowledge about the early evolution of the spire-bearing order Atrypida, spanning some 10.2 million years of time, and a global mass extinction crisis. New taxa include smooth-shelled forms such as the Late Ordovician genus Xysila, type X. astaca n. sp., and two new Early Silurian genera, Becscia, type B. scissura n. sp., and Cerasina, type C. pycnata n. sp. New costate genera include the Early Silurian reef-dwelling form Dihelictera, type D. acrolopha n. sp., and a deeper water inhabitant, Joviatrypa, type J. brabyla n. sp. For comparison with these new taxa, the spiralia and jugal processes of the type species of the Llandovery genera Protatrypa and Meifodia are illustrated and described for the first time.

A brachiopod fauna from the upper part of the Wadleigh Limestone, Alexander terrane, southeastern Alaska, is of late Frasnian age and includes the new taxa Gypidula cornuta alaskensis n. subsp., Gypidula upatensis n. sp., Gypidula perryi n. sp., Gypiduloides craigensis n. gen. and sp., Parapugnax schmidti n. sp., Westbroekina chaconenesis n. gen. and sp., Emanuella altus n. sp., Emanuella neumani n. sp., Adolfispirifer sanjuanensis n. sp., Theodossia albertoensis n. sp., Cyrtospirifer paridaensis n. sp., and Tenticospirifer wadleighensis n. sp. A few other taxa are cosmopolitan or conspecific with species known from elsewhere in western North America. The fauna overall may have North American affinities but includes an unusual number of previously undescribed forms. This lends support to the view, based on the affinities of Frasnian conodonts from this same locality (Savage, 1992) and Famennian brachiopods described from nearby (Savage et al., 1978), that these Alexander terrane faunas were not in general communication with Late Devonian North American cratonic faunas to the east.

Fossiliferous marine Devonian has been known in Chile for less than a decade. The initial discovery from south of the Salar de Atacama region, in the Sierra de Almeida, northern Chile is described together with its brachiopods. The brachiopods indicate an age span of Emsian–Eifelian or Givetian, shallow-water conditions in the Benthic Assemblage 2 range, and a biogeographic boundary region between the cool climate Malvinokaffric Realm and warmer region extra-Malvinokaffric Realms, including the Eastern Americas Realm and the Rhenish-Bohemian Region of the Old World Realm. The recent discovery of a Malvinokaffric Realm trilobite far to the south in Chile, at Buill in the Andes of Chiloe, serves to underline our very preliminary knowledge of the Chilean Devonian, whereas the alleged Devonian brachiopods from the Chonos Archipelago far to the south are probably bivalves of uncertain age.

New Middle Cambrian fossils demonstrate unusual tagmosis within the Arthropoda. Rare specimens from the Spence Shale of northern Utah are assigned to Meristosoma paradoxum n. gen. and sp. One specimen from the Marjum Formation of west-central Utah is assigned to Meristosoma sp. These taxa are further assigned to the new family Meristosomatidae. Meristosoma, which reached 17 cm in length, is characterized by a short anterior shield, a long thorax with 36 or more articulating segments, and a posterior shield with as many as 11 fused segments. Its short anterior shield and long, multisegmented thorax have a myriapodan aspect, but Meristosoma differs from all myriapods by its posterior tagmosis. In dorsal view, its posterior shield is most like that of some macropygous trilobites, but Meristosoma differs from all trilobites by having a shorter anterior shield, ringed thoracic segments without trilobation, and no ventral doublure. Phylogenetic analysis indicates that Meristosoma is a primitive and basal arthropod. A more precise taxonomic assignment is hampered by a lack of information about its limb morphology.

Two species of terebratulide brachiopods are described from the upper part of the Bateque Formation (middle Eocene) on the Pacific coast of Baja California Sur, Mexico, Terebratulina cf. Terebratulina louisianae Stenzel, 1940, and Terebratalia batequia n. sp. Terebratalia batequia n. sp. is the earliest confirmed record of the genus Terebratalia Beecher, 1893, which has been an important component of Pacific brachiopod faunas through to the present day. The occurrence of Terebratulina cf. Terebratulina louisianae Stenzel is one of the earliest records of the genus from the west coast of North America. These brachiopods, like other elements of the Bateque invertebrate fauna, may record Eocene migration from the Atlantic to Pacific Ocean via the Central American seaway.

Four species of megathyrid brachiopods from the Lower Cretaceous (Berriasian) of Crimea, Ukraine, and one species of megathyrid from the lower Upper Cretaceous (Cenomanian) of England are reinvestigated using scanning electron microscopy. The species are variously assigned to one existing genus, Praeargyrotheca Smirnova (P. hexaplicata (Smirnova) and P. megatrema (J. de C. Sowerby)) and two new genera, Krimargyrotheca (K. concinna (Smirnova) and K. balkii n. gen. and n. sp.) and Evargyrotheca (E. alta (Smirnova)). Taxa are distinguished principally on differences in shell shape, plication, and, in particular, surface microornament. The shell microstructure of all five species is investigated with particular emphasis on endopunctation and microornament. Dental plates are present briefly early in ontogeny. Based on the possession of transient dental plates, a septalium, and conspicuous microornament, Praeargyrotheca is removed from the family Megathyrididae and assigned, along with the two new genera, to a new family Praeargyrothecidae. Scanning electron microscopy study of loop development in both fossil and Recent terebratelloids and megathyrids supports a recent immunological study of living taxa from both groups that suggests that the two groups are not as closely linked phylogenetically as previously maintained. The family Megathyrididae is thus removed from the superfamily Terebratelloidea and assigned, along with the new family Praeargyrothecidae, to a new superfamily Megathyridoidea.

Several biostratigraphically important gastropod genera are described from Alberta, British Columbia, Yukon Territory, and the District of Mackenzie. Malayaspira is present in the mid-Ibexian Kechika Group. Palliseria, Maclurites, Teiichispira, Malayaspira, Barnesella, and Ceratopea occur in the Skoki Formation (highest Ibexian and lower Whiterockian) and Helicotoma and Palliseria in the Sunblood Formation (lower Whiterockian). The largest known Teiichispira operculum is illustrated. The forms are particularly useful for age determination within relatively narrow limits and most of the taxa are readily identified in the field.

The mollusk Hemithecella, which occurs abundantly both above and below the Cambrian-Ordovician boundary in the Ozark region of Missouri, is discussed and compared with Matthevia and with the polyplacophoran order Paleoloricata and found to be distinctly different. Based upon the presence of monoplacophoran-like multiple muscle scars and asymmetrical valves, Hemithecella and related forms described here are considered to be molluscan problematica. Hemithecellids are mollusks; however, their affinity to other classes is unclear although structural similarities to the Monoplacophora are noted. The new order Hemithecellitina is proposed. It contains two new families, the Hemithecellidae and the Robustidae. Three new genera, Conodia, Robustum, and Elongata, and nine new species are proposed: Conodia levicosta, C. acuminata, Robustum nodum, R. phallarium, Elongata perplexa, Hemithecella elongata, H. abrupta, H. quinquelites, and H. eminensis.

Three species of mollusks and one annelid are described from the Paleocene upper mudstone member of the Potrerillos Formation (La Popa Basin), and from the upper part of the Rancho Nuevo Formation (Parras Basin). The species described include a gastropod, a bivalve, a nautiloid and a serpulid worm, which are formally reported for first time as Paleocene fauna of the Difunta Group in northeastern Mexico. The nautiloid species provides the basis for correlation between the two sedimentary basins of the Difunta Group, as it is reported for Paleocene layers of the two formations studied. Shoreface and tidal-flat depositional environments are inferred for the Paleocene rocks of the Difunta Group.

The morphology of Argyrotheca lorioli Smirnova, 1972, from the Lower Cretaceous (Berriasian) of Crimea, Ukraine, was reinvestigated using SEM, found to be impunctate, and reassigned as the type species of a new genus Apodosia, new family Apodosiidae, order ?Rhynchonellida. Another micromorphic brachiopod, Spiriferina? oolitica (Moore, 1855) from the Middle Jurassic (Bajocian) Inferior Oolite of Somerset, England, is also reassigned to the new genus.

Previously undescribed Holmiidae from the Sectigena Zone of Morocco indicate correlation of this zone with other zones bearing Holmiidae on Baltica, Avalonia, Siberia, and Laurentia. The occurrence of the youngest Antatlasiinae in the Sectigena Zone and the oldest Protoleninae in the overlying Hupeolenus Zone suggests correlations of the Sectigena Zone with upper Atdabanian beds bearing the youngest Antatlasiinae and the Hupeolenus Zone with Botomian beds bearing the oldest Protoleninae in Siberia. The occurrence, in the overlying Hupeolenus and Cephalopyge Zones, of Paradoxides s.l. in association with the olenelloid Cambropallas and with trilobites characteristic of the Lower Cambrian “Protolenus” Zone of Avalonia calls into question the major criteria for recognition of strata of Early and Middle Cambrian age. New taxa include lyouella contracta n. gen. and sp. of the Holmiidae and Bondonella sdzuyi n. sp. of the Neltneriidae. The known species of Neltneria, N. jacqueti and N. termieri, are revised.

Newly discovered trigonioid bivalves are systematically described from the Late Albian of the Fossil Bluff Group of Alexander Island, Antarctic Peninsula. The fauna includes Nototrigonia (Nototrigonia) ponticula Skwarko, N. (Callitrigonia) offsetensis n. sp., Eselaevitrigonia macdonaldi n. sp., Pterotrigonia (Pisotrigonia) capricornia (Skwarko), and Pacitrigonia praenuntians n. sp. It represents the first Albian trigonioid fauna described from the Antarctic. It is also the first published record of the Nototrigoniinae (excluding Pacitrigonia) outside Australasia. Paleoecologically, this fauna represents the shallowest and highest energy molluscan assemblage from the Fossil Bluff Group and occurs near the base of a significant transgressive unit, the Mars Glacier Member of the Neptune Glacier Formation. The paleogeography of Austral Cretaceous trigonioids is reviewed. Endemic centers are identified in India–east Africa, southern South America, and Australasia. Only one trigonioid genus, Pacitrigonia, had its origin in the Antarctic. During the earliest Cretaceous, cosmopolitan trigonioid genera occurred in Antarctica. In the mid-Cretaceous faunal similarity of Antarctica with Australasia was strong, and in the latest Cretaceous affinity with southern South America increased.

New discoveries of trigonioid bivalves are documented from three areas in the Antartic Peninsula: the Fossil Bluff Group of Alexander Island, the Latady Formation of the Orville Coast, and the Byers Group of Livingston Island, South Shetland Islands. Eleven taxa are described, representing six genera or subgenera. The faunas are characterized by genera including Vaugonia (Vaugonia), the first Early Jurassic trigonioid recognized on the continent; Vaugonia (V.) and V. (Orthotrigonia?) in the Late Jurassic; and Iotrigonia (Iotrigonia), Myophorella (Scaphogonia), and Pterotrigonia (Pterotrigonia), which span the Jurassic–Cretaceous boundary, reaching the Berriasian stage. The following species are new: Pterotrigonia (P.) cramei n. sp., Pterotrigonia (P.) thomsoni n. sp., Vaugonia (V.) orvillensis n. sp., and V. (Orthotrigonia?) quiltyi n. sp. The faunas show affinities with those of New Zealand and southern Africa. Trigonioids characterize the shallower marine biofacies in the Jurassic of the Antarctic and reflect the principal shallowing events in the history of the region.

Lithostratigraphy and depositional and epeirogenic history of the upper Placentian Series (Cuslett-Fosters Point Formations of the Bonavista Group) and Branchian Series (Brigus Formation) are identical in the northern Antigonish Highlands; Cape Breton Island; and eastern Placentia Bay, southeastern Newfoundland. Preliminary evidence suggests that the lower Middle Cambrian is present in the field area. A unified, uppermost Precambrian–Lower Cambrian, formation- and member-level nomenclature is appropriate to Avalonian North America, and the stratigraphic nomenclature of southeastern Newfoundland is applied in northern mainland Nova Scotia.

Latest Placentian shoaling and deposition of a peritidal carbonate lithosome and unconformable onlap of the trilobite-bearing Branchian Series occurred in shallow Avalonian shale basins from eastern Massachusetts to central England.

Uppermost Placentian Series faunas are very diverse in the Fosters Point Formation. Limited similarities with the South Australian Lower Cambrian are indicated by the presence of Camenella sp. cf. C. reticulosa, Conotheca australiensis, and Hyptiotheca sp., but these forms do not contribute to highly resolved correlation.

Twenty-eight taxa are illustrated from the upper Placentian and Branchian Series. Caveacus rectus n. gen. and sp., a phosphatic problematicum, is limited to the upper Placentian Series. The oldest, skeletalized, macrophagous predators are the Pseudoconodontida and the later appearing Protoconodontida (n. orders). The Pseudoconodontida includes the Protohertzinacea n. superfamily and Strictocorniculacea n. superfamily (with the Rhombocorniculidae and Strictocorniculidae n. families). Strictocorniculum vanallerum n. gen. and sp. is described. The tommotiid family Sunnaginiidae emend. includes Eccentrotheca, Sunnaginia, Kulparina, and Jayceia deltiformis n. gen. and sp.

Demonstrating stasis in the fossil record has proven to be problematic with respect to both data collection and analysis. A previous approach is morphometric analysis of lineages sampled temporally and geographically. A hypothesis of stasis is apparently supported if morphological distances between descendent species and ancestral species are no greater than those between geographically distant samples of the descendent species. Evidence presented in this paper conflicts with such interpretations for at least one bivalve lineage, Chione erosa–Chione cancellata, of the late Neogene of tropical America. The direction and magnitude of morphological variance were quantified between two geographically distant groups of C. cancellata from the Recent, and compared to Pleistocene samples of C. cancellata and Pliocene samples of C. erosa. The results indicate that, although the magnitude of intraspecific geographic variation is as great as interspecific temporal variation, the species are morphologically discrete groups. The direction of morphological variance is as important as its magnitude, and interpretations overlooking this point are at best equivocal.