Two new conulariid species, Conularia clarkei Babcock and C. paraguayensis Babcock from the Vargas Peña Shale, are the first Silurian conulariids to be described from Paraguay. They increase to three the number of Silurian species to be described from South America. The concept of Conularia Miller in Sowerby, 1820, is emended. It includes as junior synonyms Conularia (Plectoconularia) Bouček, 1939, Diconularia Sinclair, 1952, and Yangoconularia Xu and Li, 1985. The age of the Vargas Peña Shale has long been disputed, but conclusions based on organic-walled microfossils indicate an Early Silurian (Llandoverian) age for the unit.

A disk-shaped massive colony of Tetradium, from the Middle Ordovician Bobcaygeon Formation in southern Ontario, displays features of a coral microatoll. This is the first pre-Holocene coral microatoll yet described, indicating that some tabulate corals in level-bottom communities were growing as microatolls as do many modern colonial skeleton-secreting organisms.

The microatoll therefore is not strictly a Quaternary or even Cenozoic phenomenon, but has a fossil record that may span most of the Phanerozoic. This indicates that the special conditions necessary for microatoll growth have existed outside of reef environments, and were present before the advent of scleractinian coral reefs. It may be possible to use ancient microatolls to estimate absolute water depths at low tide, thereby providing a means for estimating maximum water depths on a local and regional scale.

Among the abundant, well-preserved rhynchonellid brachiopods in the Upper Ordovician–Lower Silurian rocks of Anticosti Island, Fenestrirostra Cooper, 1955, one of the earliest camarotoechiid genera to appear in the fossil record, is probably of oligorhynchiid ancestry and seemingly endemic to the Anticosti Basin. The genus differs most obviously from other camarotoechiids in its peculiar costae, which are angular and strong posteriorly and flat and weak anteriorly.

Three successive species of Fenestrirostra, found in micritic mudstones and calcareous shales of the middle and upper Merrimack and Lower Gun River Formations, provide an example of gradualistic evolution. The most primitive species, F. primaeva, occurs only in the lower part of the middle Merrimack Formation; the descendant intermediate species, F. glacialis, occurs mainly in the upper part of the middle and in the upper Merrimack and in the lowermost Gun River Formations; and the descendant terminal species, F. pyrrha, occurs only in the lower Gun River Formation. Four major morphoseries distinguish the lineage: 1) change in the proportions and size of the shells; 2) increase in the number and concomitant loss of the costae from the anterior halves of the shells; 3) change in the orientation and reduction in the size of the hinge plates and hinge fossettes; and 4) change in the height of the median septum. The evolutionary modifications, estimated to have been accomplished in no more than 1 m.y., may have been adaptive responses to persistent low-energy marine conditions.

Biostratigraphically, the Fenestrirostra lineage provides the basis for three interval or range zones that straddle the Rhuddanian–Aeronian interstage boundary in the Anticosti Basin.

More than five thousand specimens of nine species of articulate brachiopods from the Waynesville-Liberty Formation (Late Ordovician) of southeastern Indiana were analyzed for the percentage of specimens disarticulated and the ratio of pedicle to brachial valves. Among biconvex species, the rhynchonellid Hiscobeccus capax displayed the highest ratio (2.66) of articulated to disarticulated specimens, an observation attributed to its cyrtomatodont hinge. The six orthid species from the same assemblages have much higher frequencies of disarticulated valves and deltidiodont hinges, which did not necessitate breakage of the teeth or sockets in order to disassociate the valves. Platystrophia clarksvillensis has the highest percentage of articulated specimens among the orthids, a fact attributed to the hydrodynamic stability of this species and the interlocking of the valves by the plicae around the commissure. The largest of the three concavo-convex taxa, Rafinesquina ponderosa, has the highest ratio of articulated to disarticulated specimens (3.03) and requires the fastest current velocities to transport the shells based on flume experiments.

Additionally, the deltidiodont hinge of R. ponderosa is more complex than those of Strophomena planumbona and Leptaena richmondensis, which might have increased the amount of jostling necessary to disarticulate the valves. The infrequency of brachial valves of H. capax, Hebertella occidentalis, Plaesiomys subquadrata, S. planumbona, and R. ponderosa and the pedicle valves of L. richmondensis probably reflects the comparative mechanical weaknesses of these valves given the high frequency of fragments in the biosparites, which resemble tempestites. Pedicle valves of orthids and rhynchonellids are up to 10 times thicker posteriorly relative to corresponding points on the opposite valve. Brachial valves of L. richmondensis are more than four times thicker anteriorly relative to the pedicle valve. The occurrence of posterior remnants of the fragmented brachial valve still hinged to the unfractured pedicle valve support the idea that the thinner valve is mechanically much weaker.

Inspection of the type collection of the Lower Silurian brachiopod Anabaia Clarke, 1899, from the Pitinga Member of the Trombetas Formation, shows that Harringtonina Boucot, 1972, is a junior synonym. Three species are recognized for this endemic Malvinokaffric Realm genus: Anabaia paraia, the type species from the Llandovery of the northern rim of the Amazon Basin and the Titicaca region in southern Peru, Anabaia paraguayensis from the Llandovery of eastern Paraguay, and Anabaia australis from the later Llandoverian through Ludlovian and possibly Pridolian in the Andean region extending from the Precordillera de San Juan, Argentina, north through Bolivia to the Titicaca region of southern Peru. It is predicted that Anabaia will eventually be recognized in South Africa, and probably in West Africa as well, in beds of Malvinokaffric Realm affinity.

The Early to Late Silurian sedimentary rocks of the Limestone Point and La Vieille Formations of northern New Brunswick and the Anse à Pierre-Loiselle, La Vieille, and Gascons Formations of the Gaspé Peninsula possess diverse and abundant tabulate coral faunas that include six species of Heliolitidae distributed among Heliolites and Stelliporella. Two species, Heliolites laxus and Heliolites distinctus, are new. A revised concept of the genus Heliolites is proposed. The Heliolitidae from this region show a substantial degree of endemism and are most similar to northern European faunas.

The distribution of individual heliolitid species was under a high degree of facies control. The heliolitids are more restricted in distribution than are other groups of Tabulata in this region and are most abundant in open shelf and carbonate bank facies.

A fragmentary and probably immature polyplacophoran shell from the Middle Triassic Germanic Muschelkalk is presented. Morphological peculiarities of the specimen are a stiff connection of the head valve to the adjoining intermediate valve and the presence of a yet undescribed brim-like shell constituent, informally called border-plate herein. The unusually well-preserved shell structure is discussed in detail comprising tegmentum, crossed-lamellar p. hypostracum and the (articulamental?) border-plate. Characteristics indicate a systematic position within the order Lepidopleurina.

Oriostoma bromidensis n. sp., the oldest reported occurrence of Oriostoma Munier-Chalmas, 1876, is described from the Bromide Formation (Middle Ordovician, Blackriverian) of Oklahoma. The species is also the oldest known representative of the family Oriostomatidae Wenz, 1938. It is one of few gastropods known from the Bromide and is smaller than the widespread and abundant Oriostoma typical of the Silurian.

Marginovatia is proposed as a new genus of small North American linoproductid brachiopods that developed a narrow shelf around the anterior and anterolateral margin of the visceral disc in the brachial valve and a corresponding small flange in the pedicle valve interior. When the valves closed, these structures fit together and helped seal off the visceral cavity. This genus first appeared in the Late Mississippian (late Meramecian), continued through the Early and earliest Middle Pennsylvanian (Morrowan), and may have continued into the early Middle Pennsylvanian (Atokan). In addition to the type species, Productus inflatus var. minor Snider, seven species are assigned to this genus: Marginovatia aureocollis n. sp., M. catinulus n. sp., Linoproductus duodenarius Easton, M. eurekensis n. sp., M. manardensis n. sp., Productus (Linoproductus) semicubiculus Bell, and L. pumilus Sutherland and Harlow. An eighth species, identified as Marginovatia aff. M. pumila (Sutherland and Harlow), occurs in rocks of probable middle to late Morrowan or Atokan age in southeastern Alaska.

Lower and Middle Devonian brachiopod-dominated communities of Nevada are numerous (46) and most are positioned on or adjacent to the carbonate-platform foreslope or ramp. Level-bottom community chains are fundamentally different from community associations that are interrupted by a platform margin. All communities require relative abundance data of constituent species for recognition. These communities prove to be endemic to the Nevada-southeastern California area, even though faunal similarities with distant regions in North America can be recognized. Analogous communities, the same age as comparable communities in Nevada, differ in overall specific content and in relative abundance of diagnostic species. Identification of analogous communities requires recognition of common physical environments (first) and faunal similarity (second). Groupings of communities based on presence-absence data of key species and genera are not meaningful.

Biofacies boundaries sited on carbonate-platform foreslopes separate community associations and also act as filter boundaries for faunal realms. The platform and peripheral biofacies thus delineated are also realms, a pattern that is repeated by different organisms from Cambrian to Cenozoic. Biofacies boundaries shift in concert with large-scale sea-level fluctuations. During platform emergence, most faunas are peripheral and therefore cosmopolitan. Transgression initially forms small, isolated epeiric seas populated from offshore, and endemic faunas evolve. Increased transgression merges epeiric seas and faunas, reducing provinciality and diversity through competition. Regression results in extinctions in proportion to its rate and the area involved. The cycle repeats.

The hermanni-cristatus conodont Zone is replaced with the name hermanni Zone. The disparilis Zone is divided into Lower and Upper Subzones. The norrisi Zone is proposed at the top of the Middle Devonian.

Extensive collections from stratigraphically controlled sections allow reassessment and systematic revision of Middle Jurassic inoceramids from Argentina. Two species are doubtfully referred to Parainoceramus Voronetz, including P.? westermanni n. sp. Five species of Retroceramus Koshelkina, including R. cf. R. marwicki (Speden), R. patagonicus (Philippi) and R. stehni n. sp., are present. The Bajocian–early Callovian species of Retroceramus show strong affinities with Aalenian–Bathonian inoceramids from the Northern Hemisphere, and also with the South Pacific forms of the galoi–haasti group of Heterian–Ohauan age, except for minor differences in outline, ornamentation, and the umbonal region.

The time range of each species in Argentina was determined by associated ammonoids. There is strong morphological evidence, supported by the stratigraphic distribution of species, that Retroceramus cf. R. marwicki, R. patagonicus, and R. stehni belong to a single clade, which developed from the late Bajocian to the early Callovian in the Andean region.

The rhynchonellid genus Ptilorhynchia Crickmay and the terebratulid genus Sellithyris Middlemiss are described from Mexico for the first time. This is the first formal description of Sellithyris from the American Continent. Ptilorhynchia (Proteorhynchia) imlayi n. sp. is described from the late Aptian of the La Penã Formation, Coahuila. “Rhynchonella’ durangensis Imlay from the Valanginian of the Carbonera Formation, Durango, is assigned to Ptilorhynchia (Proteorhynchia). “Terebratula’ coahuilensis Imlay from the Valanginian Barril Viejo Formation, Coahuila, is referred to Sellithyris. Sellithyris coahuilensis indicates close links with contemporaneous Valanginian faunas of southern Europe. During the early Early Cretaceous Sellithyris had a fairly restricted latitudinal and broad longitudinal distribution (Tethys and its extension across the opening Central Atlantic Ocean). Ptilorhynchia (Proteorhynchia) in Mexico is significant as the first low-latitude record for Ptilorhynchia. Other Lower Cretaceous records are from northern and southern high latitudes, previously interpreted as a bipolar distribution. It is suggested that Ptilorhynchia had a Boreal-East Pacific distribution with Ptilorhynchia (Proteorhynchia) being a low-latitude Early Cretaceous offshoot. The genus may prove to be pandemic. Proteorhynchia Owen is regarded as a subgenus of Ptilorhynchia.

The hyolithid species Hyolithes crebescens Resser and Endo, Hyolithes cybele Walcott, and Hyolithes delphus Resser and Endo from the Middle Cambrian of China are assigned respectively to the genera Nevadotheca Malinky, Novakotheca n. gen., family Hyolithidae, and Crestjahitus Syssoiev, family uncertain, all in the order Hyolithida. Recognition of Nevadotheca extends its geographic range from North America to China, and the occurrence of Crestjahitus in the Middle Cambrian of China increases its geographic and stratigraphic distribution from the Early Cambrian of the Soviet Union.

Poor preservation of the type specimens of Hyolithes? aliger Resser and Endo, H.? aplatus Resser and Endo, H.? cariniferus Resser and Endo, H.? daphnis Walcott, H.? delia Walcott, H.? endoi Howell (as H. ornatus Resser and Endo), H.? mantouensis Resser and Endo, and H.? tenuis Resser and Endo renders their generic identification uncertain. Hyolithes (Orthotheca) glabrus Resser and Endo is here transferred to the hyolith order Orthothecida Marek and referred with question to Decoritheca Syssoiev, family Novitatidae.

Morphology of the types of “Hyolithes” fuchouensis Resser and Endo, “H.” kuantungensis Resser and Endo, “H.” sondai Resser and Endo, “Orthotheca” daulis Walcott, and “O.” doris Walcott does not support assignment to the Hyolitha for these species; their phylogenetic affinity is uncertain.

The marine bivalve Fimbria susanensis n. sp. is reported from the uppermost Paleocene part of the “Meganos Stage” in the upper Santa Susana Formaton, Simi Hills, southern California.

Fimbria pacifica n. sp. is reported from the middle lower Eocene “Capay Stage” strata of the Pacific coast of southwestern North America. The new species is present in the lower Bateque Formation, Baja California Sur, Mexico, and in the lower Juncal Formation, Whitaker Peak area and Santa Ynez Mountains, southern California.

Fimbria susanensis n. sp. and F. pacifica n. sp. are the only fimbriids known from the Pacific coast of North America. Previously reported Pacific coast species, which gave a range of Late Cretaceous to late Eocene for this genus in this particular area, do not belong to Fimbria.

A new terebratellid brachiopod species, Modestella jeletzkyi n. sp., is described from the Early Cretaceous of Prince Patrick Island, Northwest Territories, Canada. The occurrence extends the paleobiogeographic range of Modestella from northwest Europe into the northern high-latitudes of the North American continent. This new record of Modestella suggests brachiopod dispersal between northwest Europe and North America via the East Greenland Seaway, probably during the Albian. The occurrences of two other Cretaceous terebratellid genera, Advenina and Psilothyris, are updated. They are both homeomorphic with Modestella. Advenina, from the Tethyan and Jura regions of Europe, is now recorded from the Early Cretaceous of Sardinia. The occurrence of Psilothyris in North America and Europe is best explained by dispersal through the opening central Atlantic Ocean, indicating the continuation of Hispanic Corridor-type faunal links established during the Jurassic.

Permian corals of Bolivia are confined to the Lower Permian (Wolfcampian, Leonardian) Copacabana Limestone. The coral fauna of the formation in the Lake Titicaca to the central altiplano areas of the Department of La Paz consists of two solitary rugose coral species, two colonial rugose coral species (one each of fasciculate and cerioid), and two tabulate coral species. New taxa are Stylastraea branisai n. sp., Durhamina pandolfi n. sp., Michelinia escobari n. sp., and Cladochonus carrascoi n. sp. Lophophyllidium striatum (d'Orbigny, 1839), based on Bolivian specimens, is redescribed, a lectotype designated, and the range extended to North America. Although the fauna is small, its taxonomic composition shows clear affinity with faunas of similar age northward through South and Central America to Mexico and the USA Texas-Oklahoma-Midcontinent region. The Bolivian fauna thus is confirmed as belonging to the Cyathaxonid Coral Province, which is restricted to the above areas. A species of Durhamina previously erected for Guatemalan specimens occurs in the Copacabana Limestone of Peru and strengthens the province assignment of the formation.

Re-examination of some North American collections of the late middle to early late Norian pterioid bivalve Monotis confirms the separation of M. (M.) alaskana Smith from the European type species M. salinaria (Schlotheim). The related M. (M.) haueri Kittl, as differentiated statistically, is more widely represented in southern Alaska, the Canadian Yukon, and Nevada than was formerly recognized. Species described originally from northeastern USSR and now confirmed as present in rocks from Alaska and western Canada include: M. (Entomonotis) pachypleura (Teller), M. (Eomonotis) daonellaeformis Kiparisova, and M. (E.) anjuensis Bytschkov and Efimova. Monotis subcircularis Gabb and related forms are transferred from the subgenus Entomonotis to the new subgenus Pacimonotis in order to give the former subgenus a more homogeneous morphologic range.

Re-evaluation of the stratigraphic occurrences of these species shows that M. alaskana occurs above M. subcircularis and below M. haueri in the Wrangell Mountains, Alaska. Elsewhere in North America, however, Monotis haueri occurs at the same level as M. subcircularis and is thus a long-ranging form. These three taxa, as well as M. pachypleura, are representative of the upper Norian Cordilleranus Zone. Monotis daonellaeformis is among the oldest Monotis species of the middle Norian Columbianus Zone; M. anjuensis in North America is probably also from the Columbianus Zone but could overlap in occurrence with the upper Norian M. subcircularis.

A new species of the late Mesozoic–Cenozoic family Ringiculidae (Ringicula (Ringicula) cockburnensis n. sp.) is described from basal glauconitic beds of late Eocene age of Cockburn Island, Antarctica, and is the first reported occurrence of the family Ringiculidae from the continent of Antarctica. Ringicula (R.) cockburnensis n. sp. most closely resembles R. castigata from the middle Oligocene Duntroonian Stage of New Zealand and provides further support for the strong provinciality (Weddellian Province) that existed along the southern margin of the Pacific during the Late Cretaceous and early Tertiary.

Late Osagean to Meramecian Platycrinites and Eucladocrinus from Illinois, Iowa, and Missouri are redescribed and redefined from study of type material. Three of the oldest species were incorrectly synonymized with P. sarae, and this correction leads to a realignment of species systematics within Platycrinites. Accordingly, six species of Platycrinites and one species of Eucladocrinus are considered valid in the Keokuk Limestone through St. Louis Limestone of the stratotype area. Valid species include Platycrinites saffordi (Hall), P. sarae (Hall), P. georgii (Hall), P. pumilus (Hall), P. brevinodus (Hall), P. niotensis (Meek and Worthen), and Eucladocrinus millebrachiatus Wahsmuth and Springer. Nomenclatoral changes include the following: 1) P. sarae is redescribed and all junior synonyms are removed; 2) P. georgii is a valid senior synonym of P. bonoensis (White), P. aeternalis (Miller), P. boonvillensis (Miller), and P. cauducus; 3) P. pentagonus (Miller) is a junior synonym of P. niotensis; 4) P. pumilus is a valid senior synonym of P. prattenanus (Meek and Worthen), and P. monroensis (Worthen); 5) P. bloomfieldensis (Miller) is designated as a nomen dubium; and 6) Eucladocrinus millebrachiatus immaturus is a junior synonym of E. millebrachiatus.

The evoluton of new species in Platycrinites was by a combination of cladogenesis and possibly anagenesis. Platycrinites sarae evolved from P. saffordi possibly through anagenesis, P. pumilus evolved from P. niotensis through cladogenesis, and P. hemisphaericus evolved through cladogenesis from P. brevinodus, although P. hemisphaericus does not occur in the geographic area of this study.

Groomodiscus rossi n. gen. and sp., a bellerophontacean from the Ordovician of Nevada that uncoiled at maturity, is described and placed in the Gastropoda. The deep notch or sinus of the shell is interpreted to have functioned the same as a deep slit, and the new genus is placed within the tropidodiscinids. Uncoiling and thickening of the shell in the mature stage of growth is probably an indication of a fundamental change of life style to a sedentary mode. Fragmentary specimens of the final, uncoiled portion of the whorl resemble the apertural portion of hyoliths. From a functional viewpoint, compressed planispiral shells are concluded more likely to be gastropods than monoplacophorans.