A diverse, well-preserved assemblage of nautiloid cephalopods was collected from the Treptoceras duseri shale, a 1.5-m-thick claystone within the Waynesville Formation (Late Ordovician, early Richmondian) exposed in southwest Ohio. The strata, the enclosed fauna, and its taphonomy indicate deposition in a low-energy, mud-bottom marine environment, in water depths of 20–25 m, below wave base but within the zone of storm-current reworking.

Nautiloid specimens consist of complete conchs that have been replaced by calcite. Twelve species of nautiloids, belonging to eight genera, representative of four orders, have been collected from the shale in southwest Ohio. Longiconic orthocones are clearly the dominant nautiloid morphotype present, with the assemblage dominated by three species of the longiconic orthocerid Treptoceras and with fewer numbers of the endocerid Cameroceras and the slender orthocerid Isorthoceras?, the cyrtoconic oncocerids Oncoceras and Manitoulinoceras, and rare specimens of the orthocerid Gorbyoceras, the oncocerid Zittelloceras, and the ascocerid Schuchertoceras.

Nautiloid taphonomy, the diversity of nautiloid taxa present, the lack of postmortem buoyancy in the shells of the more common taxa, the recurrent nature of this assemblage, and the restricted distribution of this Treptoceras–Cameroceras fauna to portions of eastern North America in the Late Ordovician suggest that this nautiloid assemblage represents an in-situ accumulation of nautiloids representative of a living assemblage. These nautiloids were important elements associated with benthic communities in these epeiric sea mud-bottom environments and not simply assemblages of drifted, necroplanktonic shells.

New finds of the trilobites Cobboldites tichkaensis Geyer, 1988, Pseudocobboldia pulchra (Hupé, 1953), Protolenus (Protolenus) densigranulatus Geyer, 1990, Latoucheia (Latoucheia) tichkaensis Hupé, 1953, and Acanthomicmacca neltneri Hupé, 1953, from the basal Middle Cambrian near the peak of Tizi n'Tichka in the central High Atlas, Morocco, supplement the known morphology of these species; the trilobites Acanthomicmacca new species, Oreisator tichkaensis new genus and species, and “Parasolenopleura” sp. from that locality are new. Acanthomicmacca neltneri is the first species of the genus and family that is described and figured in detail in terms of morphologic plasticity and ontogeny; Oreisator tichkaensis is the first ptychopariacean trilobite formally described and based on material from Africa. Trilobites and other fossils from the locality suggest a strong affinity to other Mediterranean and to Avalonian faunas, which is well supported by helcionelloid and hyolith genera.

A new genus and species of Unionoidea, Tacuaremboia caorsii, are described from the Tacuarembó Formation (Upper Triassic–Upper Jurassic) of Uruguay. The genus is distinguished from other Unionoidea by its large size, thickness, edentulous hingeline, and the presence of claustra. It has some similarities with the Anodontinae and the Archanodontacea, but it cannot be assigned to any of the known family units.

Thirty-four species of trilobites belonging to 21 genera are recognized in the Albertella Biozone within the Grassy Spring Member (new name) of the Pioche Shale of southeastern Nevada. Genera include Pagetia, Poliella, Kootenia, Olenoides, Albertella, Albertellina, Albertelloides, Delamarella, Mexicaspis, Paralbertella, Ptarmiganoides, Ursinella, Zacanthoides?, Amecephalites, Mexicella, Nyella, Onchocephalites?, Pachyaspis, Panacus, Plagiura, and Volocephalina. Two new corynexochid genera and species, Delamarella brevispinaspis and Ursinella major, are described. The existing corynexochid genus Albertella is revised to include two new species, A. fritzi and A. highlandensis. A new species, Albertelloides kitai, is described. Two new ptychopariid genera, Amecephalites and Panacus, plus four new ptychopariid species, Amecephalites sundbergi, Mexicella granulata, Panacus palmeri, and Volocephalina variosa, are described and Nyella immoderata Palmer is revised. In addition, the Albertella Biozone is divided into three new subbiozones, the lower Albertellina aspinosa Subbiozone, the middle unnamed subbiozone, and the Albertella highlandensis Subbiozone.

Disarticulated net-like plates of the lobopod Microdictyon had a near cosmopolitan distribution from the early to middle Cambrian but are yet to be documented from the North China Platform. Here we report isolated plates of Microdictyon from the lower Cambrian Xinji Formation (Stage 4, Series 2) of the North China Platform, extending the paleogeographic distribution of Microdictyon in the early Cambrian. The plates of Microdictyon from the Xinji Formation are similar to those of other species established on the basis of isolated plates but do bear some new characters, such as mushroom-shaped nodes with a single inclined platform-like apex and an upper surface that displays radial lines. However, the plates documented here are left under open nomenclature due to inadequate knowledge of intraspecific and ontogenetic variation and low specimen numbers. Through comparison of the node shapes of the isolated plates of different Microdictyon species, we consider that low mushroom-shaped nodes could be a primitive and conservative character of Microdictyon while tall mushroom-shaped nodes may be a derived character. Subtle differences in shape and number of node apices may also represent intraspecific or ontogenetic variation.

Conodont faunas recovered from the upper 80 m of Late Permian limestones on the Greek island of Hydra (Idhra) include Neogondolella leveni (Kozur, Mostler, and Pjatakova), Neogondolella orientalis (Barskov and Koroleva), Hindeodus julfensis Sweet, Xaniognathus hydraensis n. sp., and Ellisonia sp. The conodonts occur with a rich assemblage of silicified brachiopods, fusulines, and other invertebrates. Diagnostic fusulines include Reichelina media Miklukho-Maklai and Palaeofusulina cf. P. prisca Deprat. The conodont and fusuline faunas are correlative with well-known faunas described from the lower part of the Ali Bashi Formation of the Djulfa region of Iran, and with similar faunas described from other regions of Central Asia. The presence of conodonts from the Neogondolella orientalis Zone of Kozur indicates that the age of the upper part of the Permian sequence on Hydra is early-middle Dzhulfian (Baisalian Substage).

Seven previously described and seven new taxa of gyrodiform naticoids from West Coast Late Cretaceous–Paleocene age strata are discussed. Gyrodes (Gyrodes) dowelli White of Turonian age is a typical Gyrodes; G. robustus Waring from the Paleocene has the shape of Gyrodes s.s. but lacks the crenulations. G. greeni Murphy and Rodda, G. yolensis n. sp., G. quercus n. sp., G. banites n. sp., G. canadensis Whiteaves, G. pacificus n. sp., and G. expansus Gabb comprise the new subgenus Sohlella, which thus ranges from Cenomanian through Maastrichtian. Gyrodes robsauli n. sp. resembles “Polinices” (Hypterita) helicoides (Gray), and Hypterita is reassigned to the Gyrodinae as a subgenus of Gyrodes. Gyrodes onensis n. sp. of Albian age is similar to the G. americanus group of Sohl (1960). Three texa—Natica allisoni (Murphy and Rodda) of Cenomanian age and N. conradiana Gabb and N. conradiana vacculae n. subsp. of Turonian age—which have all been previously considered to be Gyrodes are placed in Natica. Well marked relict color patterns on N. conradiana and N. conradiana vacculae suggest that these naticids from northern California and southern British Columbia were tropical forms.

Diversity of taxa and size of specimens are reduced at the end of the Turonian, suggesting a change in West Coast marine conditions at that time.

A new genus and two new species of late Paleozoic edrioasteroids, Giganticlavus bennisoni and G. gelasinus, are described from the Early Pennsylvanian of Oklahoma and New Mexico. Giganticlavus differs from other clavate edrioasteroids by its large size, extreme ambulacral length and ambital overlap, extreme thickness of interambulacral and recumbent zone plates, and the tessellate nature of the recumbent zone plating. The extreme length of ambulacra and thickness of the plating are interpreted as adaptations for increased size and rigidity.

To clarify the systematic positions of the important gonyaulacacean genera Operculodinium Wall, 1967 emend. Matsuoka et al., 1997 and Protoceratium Bergh, 1881, we present in detail the tabulation of the Oligocene–Pleistocene, thermophilic, cyst-defined species Operculodinium bahamense Head in Head and Westphal, 1999 emend., and the extant, cosmopolitan, theca-defined species Protoceratium reticulatum (Claparède and Lachmann, 1859) Bütschli, 1885. Both species have a sexiform hyposomal tabulation, and L-type (Protoceratium reticulatum) or modified L-type (Operculodinium bahamense) ventral organization. Protoceratium reticulatum has dextral torsion of the hypotheca, requiring assignation of the genus to the subfamily Cribroperidinioideae Fensome et al., 1993, whereas Operculodinium bahamense has neutral torsion requiring assignation to the subfamily Leptodinioideae Fensome et al., 1993. The stratigraphic range of this subfamily is now extended upwards to the lower Pleistocene. Paradoxically, Protoceratium reticulatum produces a cyst whose morphology is circumscribed by the cyst-defined genus Operculodinium, either implying polyphyletic origins for this genus or that combinations of ventral organization and torsion used to subdivide the family Gonyaulacaceae cannot always be applied rigidly. In detail, Operculodinium bahamense is shown to have an unusual ventral tabulation in which the first apical plate contacts the apical pore complex but not the sulcus. The new term “episert” is proposed to describe this plate relationship, which appears to have evolved independently in several lineages of the suborder Gonyaulacineae.

A delicate and well-preserved latest Permian radiolarian fauna was obtained from muddy siliceous rocks and siliceous mudstones in the Dongpan Section, southwest Guangxi, China. the specimens of family Albaillellidae in the fauna have been selected for taxonomic study in this paper. Two genera and 14 species belonging to this family are recognized and described, including three new species and one new subspecies, namely Neoalbaillella minuta, Albaillella flabellata, Albaillella fida, and Albaillella yaoi longa, respectively. This assemblage is correlated to the Neoalbaillella optima Assemblage Zone. Its biostratigraphic significance and the final extinction of Albaillellidae at the end of Late Permian are observed and discussed herein.

A review of the Late Ordovician, chiefly mid-Ashgillian, to Early Silurian, Llandoverian, pentameroidean brachiopods, the Virgianidae, permits them to be assigned to three subfamilies (Virgianinae [10 genera assigned], Mariannaellinae [5 genera assigned], Pleurodiinae [2 genera assigned]). Diagnoses are presented for each subfamily, with comments on diagnostic characters for each genus and species. All the genera occur in what are interpreted to have been relatively low latitude, warm water environments in Arctic North America, northern Europe, northern Asia, central Asia and South China; the presence of Australian Ordovician virgianids is uncertain at this time. The mid-Ashgillian pentameroid adaptive radiation was followed by latest Ordovician mass extinction, subsequently surviving recovery and radiation in the middle-Late Llandovery. Silurian radiations convergently mimicked the Ordovician event in many respects.

New specimens of an as yet unidentified carnivoran from the earliest Paleocene of Saskatchewan are described. The new specimens augment the evidence on which the contentious earliest (middle Puercan) occurrence of Carnivora is based, provide novel information of the lower dentition of the earliest carnivorans, and provides evidence for the earliest taxonomic diversity in Carnivora.

Recent field work at the Deseadan (late Oligocene) locality of Quebrada Fiera (Mendoza Province, Argentina) has provided new fossil remains that greatly increased the faunal assemblage of this site. A good number of specimens correspond to the Family Archaeohyracidae (Notoungulata) and are presented in this paper. Most of them are recognized as a unique taxon, corresponding to the genus Archaeohyrax, characterized by the presence of a strong, shallow, wide sulcus on the labial side of the talonid of m3. At specific level, it is identified with the species A. suniensis previously recognized at Salla (Bolivia). Specimens with different tooth wear degree show an intraspecific variation in occlusal morphology comparable to that observed among the Bolivian material. In addition to A. suniensis, an isolated p2 is tentatively related to Archaeotypotherium, due to their hypsodont but rooted condition and larger size. Two other isolated lower molars from this site had been previously related to this genus but they are comparable to the new specimens ascribed to Archaeohyrax. The identification of Archaeotypotherium is not well supported at present, but if later confirmed, it would increase the temporal distribution of the genus, so far recorded in Tinguirirican (early Oligocene) localities of Chile and Argentina. The recognition of A. suniensis in Quebrada Fiera establishes a greater affinity with the lower latitude Deseadan fauna of Salla than with that from Patagonia, where the genus is represented by A. patagonicus. Other faunal elements from Quebrada Fiera, however, do not support this affinity with Bolivia. Xenarthrans or some marsupials are equivalent to those from Patagonia, while other taxa such as the recently described notohippid or a rare, tiny metatheria are at present exclusive for Mendoza. The increasing knowledge of the Quebrada Fiera assemblage contributes to a better understanding of the paleogeographic scenario of Southern South America during late Oligocene.

A well-preserved mouth apparatus consisting of jaws and a radula was found in situ within the body chamber of the goniatite Cravenoceras fayettevillae Gordon, 1965 (Neoglyphiocerataceae: Cravenoceratidae), from the middle Chesterian (Upper Mississippian) of Arkansas. Both upper and lower jaws consist of a black material. The lower jaw is characterized by a widely opened larger outer lamella and a shorter inner lamella. The upper jaw is fragmental. The radula is preserved in the anterior portion of the buccal space and comprises a series of tooth elements. Each transverse tooth row consists of seven teeth (a rhachidian and pairs of two lateral and one marginal teeth), with a pair of marginal plates. This arrangement is typical of radulae of other ammonoids of Carboniferous to Cretaceous age, coleoids, and the orthoconic “nautiloid” Michelinoceras (Silurian, Michelinocerida), suggesting a phylogenetic affinity among them.

At the southernmost tip of South America, a thick pile of deep marine volcaniclastic rocks called the Yahgan Formation (Kranck, 1932) was deposited during the Early Cretaceous in a small marginal basin developed between the continent and a Pacific-facing volcanic arc (Katz, 1972; Dalziel et al., 1974). North and northwest of Tierra del Fuego, in the adjacent Austral or Magallanes basin, this unit is laterally replaced by coeval, fine-grained deposits representing basinal, slope, and platform marine settings (Winslow, 1982; Biddle et al., 1986; Wilson, 1991). The geometry of the basins changed markedly with a compressional event that produced the tectonic inversion of the marginal basin and the formation of a retroarc foreland basin in front of the rising cordillera. Closure of the marginal basin and strong deformation of the Yahgan Formation apparently occurred in the mid-Cretaceous (Halpern and Rex, 1972; Dalziel et al., 1974; Wilson, 1991); however, the timing of the opening and closing of the basin is poorly constrained because of the scarcity of fossil evidence. So far, a Late Jurassic-Neocomian age was favored for the Yahgan Formation on the basis of the record of belemnites and ammonites (Aguirre Urreta and Suárez, 1985; Halpern and Rex, 1972; Winn, 1978). Halpern and Rex (1972) mentioned the Hauterivian genus Favrella in Gardiner Island, but this record has been questioned by Thomson et al. (1982) who considered the ammonite imprint to be some kind of heteromorph. Also, the timing of the transition from marginal to foreland basin is not well documented. On the basis of indirect evidence the initiation of the foreland basin stage was assigned to the Albian in the Ultima Esperanza region of Chile (Wilson, 1991) and to the Late Cretaceous in northern Tierra del Fuego (Biddle et al., 1986). Recent field work by the authors in the area of No Top Mountain-Moat River, Tierra del Fuego (Figure 1), has resulted in the first record of diagnostic late Albian inoceramids in the Yahgan Formation. The objective of this note is to document this fauna and to briefly discuss its implications on the control of the timing of the transition from marginal to foreland basin in the area.

Outcrops of upper Miocene to upper Pliocene sediments in the Bocas del Toro Basin, Caribbean coast of western Panama, contain a record of the emergence of the southern Central American isthmus. Paleodepths and characteristics of past sedimentary regimes within the basin were determined from benthic foraminiferal species assemblages. The present Valiente Peninsula shallowed from upper bathyal depths of about 300–500 m to outer neritic depths of 150–200 m between latest Miocene (5.6–6.5 Ma) and middle Pliocene (3.5–3.6 Ma) times. Outer neritic assemblages from about 100–150 m paleodepth on the island of Escudo de Veraguas indicate negligible emergence through the late Pliocene, and their present sea-level altitude suggests rapid Quaternary shallowing. Middle neritic foraminiferal assemblages of Cayo Agua island shallowed from depths of about 40–80 m to 20–40 m between early (4.5–5.0 Ma) and middle (3.5–3.6 Ma) Pliocene times. Cayo Agua assemblages indicate establishment of a carbonate regime in the southwestern Caribbean region prior to complete closure of the Caribbean–East Pacific seaway around 3.5 Ma.

Aulacopleurine trilobites from Llandovery strata of the Whittaker Formation in the central Mackenzie Mountains, Northwest Territories, Canada, include Aulacopleura andersoni n. sp., Aulacopleura? ranfordi n. sp., and Songkania smithi n. sp. The subfamily Aulacopleurinae consists of only the genera Aulacopleura Hawle and Corda, 1847, and Songkania Chang, 1974, characterized by smooth, broad early growth stages and holaspides having expanded frontal and genal areas, covered with dense caecal pits, but usually very subdued tuberculate sculpture. The relationship of Aulacopleura? ranfordi and A.? reedi Přibyl, 1947, to the remainder of species assigned to the genus is ambiguous.

Morphometric analyses of shell morphology in the Cretaceous nautiloid Eutrephoceras clementinum (d'Orbigny, 1840) (Cephalopoda, Mollusca) from the Ariyalur area, southern India, reveal ontogenetic change from hatching to maturity as well as intra-specific variation in shell morphology. the shell breadth has a negative allometric relationship with shell diameter and with whorl height, and the umbilicus diameter has a positive allometric relationship with shell diameter. This shows that shell shape became relatively thinner with less variation, and the umbilicus diameter became relatively broader with growth. the siphuncle position moves from a dorso-central to ventro-central position with growth. A constriction was recognized on the early whorl at 20 mm in shell diameter, and the interval angles of succeeding septa were changed at the 8th septum, indicating that they hatched at this stage. the bending of umbilical walls of apertures toward the center of coiling suggests that E. clementinum attained maturity at about 115 mm in shell diameter. the comparison of the shell morphology of E. clementinum with that of E. bouchardianum (d'Orbigny, 1840) reported in the literature clarifies their difference in whorl shape and umbilical size, especially in the adult stage. This kind of morphometric study of nautiloids is essential for elucidating their adaptive designs for environment and mode of life, functional shell morphology, taxonomy, phylogeny, and evolution.

The ankylosaurine Pinacosaurus is one of the best known ankylosaur to date in terms of the number and preservational quality of specimens. Juvenile to sub-adult postcrania collected by the Soviet-Mongolian Paleontological Expedition from the Upper Cretaceous Alagteeg Formation at Alag Teeg, Mongolia can be assigned to Pinacosaurus grangeri based on discrete cranial characters. One individual is significantly larger than the others and demonstrates delayed fusion of postcranial elements with the earliest occurring between dorsal ribs and vertebrae. The robustness of forelimb elements is positively allometric with respect to their length, indicating weight-bearing relationship. Such length-dependent correlations are not seen in the hind limbs. Finally, incipient cervical half rings suggest a developmental pathway of outgrowths from the underlying band combined with fusion of overlying osteoderms.

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.