Previously unstudied and earlier-known specimens have revealed the wide cephalic doublure and median ventral suture in Stenopilus; the hypostome is unknown but was probably natant. The cranidium of S. pronus differs from that of the type species S. intermedius in its greater length and convexity; the pygidium is known from rare complete specimens. These two species are present in Quebec, Newfoundland, and Vermont. They are differentiated from Leiocoryphe, which also had a highly effaced cephalon. Relationships remain problematic between these two genera and others currently placed in Plethopeltidae. An enrolled specimen of S. pronus is refigured and the anatomy and mode of life considered as that of a vagrant benthic animal rather than one that lived in a burrow as previously thought.

Middle and Upper Ordovician Triarthrinae from the Precordillera of San Juan, Argentina, include the Whiterock/Llanvirn Porterfieldia turneri (Baldis and Pöthe, 1995) and P. acava new species, and the early Caradoc Triarthrus jachalensis (Harrington and Leanza, 1957). Each of these species is described based on silicified material, including ontogenies, from the Las Aguaditas Formation. Porterfieldia maanssonae new species from the lower member of the Gualcamayo Formation (late Arenig) at Río Gualcamayo, San Juan Province, and Río Guandacol, La Rioja Province, is closely allied to P. turneri. Two protaspid stages are present in Porterfieldia, whereas mineralized protaspid stages are apparently lacking in Triarthrus jachalensis. Triarthrus jachalensis was capable of sphaeroidal enrollment by meraspid degree 2. Precordilleran species bear closest comparison to others from Spitsbergen (Porterfieldia acava n. sp. and P. parapunctata) and Sweden/Norway (Triarthrus jachalensis and T. linnarssoni).

Two lineages exist for Cahabagnathus. Lineage 1 is C. friendsvillensis–C. chazyensis–C. sweeti–C. carnesi. Three new species are proposed in lineage 2, which consists of C. baueri n. sp.–C. directus–C. cooperi n. sp. and C. craigi n. sp. The distribution pattern of Cahabagnathus was strongly influenced by Chazyan sea-level changes. The wide distributions of C. friendsvillensis and C. sweeti correspond to two large transgressions and the more narrow distribution of C. chazyensis and C. carnesi correspond to regression events. A similar relationship exists between sea-level change and the distribution of species in lineage 2. Evolution of the cahabagnathids was apparently influenced by the rise of sea level, which widely distributed taxa, and the fall of sea level, which isolated taxa. We propose that it was from peripheral isolates of widely distributed taxa that endemic Cahabagnathus taxa (C. baueri, C. cooperi, C. craigi, C. chazyensis, and C. carnesi) evolved.

This paper describes a unique deepwater brachiopod fauna from the upper part of the Talung Formation at the Dongpan Section, southern Guangxi, South China. This brachiopod fauna includes 10 species belonging to 10 genera. New taxa are Anidanthus mucronata n. sp., Dongpanoproductus elegans n. gen. and sp., Costatumulus dongpanensis n. sp., and Spinomarginifera semicircridge n. sp. This fauna is characterized by small, thin-shelled species with high abundance and low diversity, and therefore is different in generic and species composition from the coeval faunas of the Late Permian limestone facies in South China. The brachiopod fauna can be safely assigned to the latest Changhsingian as indicated by the presence of abundant Paracrurithyris pigmaea, the immediately underlying radiolarian Neoalbaillella optima Zone of late Changhsingian age, and the overlying ammonoid Ophiceras sp. cf. O. tingi Tien of the lowest Triassic. This fauna is most likely to have lived in a deepwater environment as indicated by coexistence with the radiolarian Latentifistularia, small thin-shelled brachiopods, and the dominance of silica-bearing mudstone.

Abundant fossil and modern specimens of the bivalve Panomya collected from Hokkaido, northern Japan, belong to five extant species, including P. norvegica and P. trapezoidis (both no longer present in Japan), and P. beringiana, P. nipponica, and P. ampla for modern specimens. I examine the taxonomy for these species around Japan and also for the extinct P. simotomensis and P. izumo from Japan and discuss the geographic history of Panomya. Panomya originated during the latest Oligocene to middle Miocene in the northeastern Gulf of Alaska. Subsequently, P. simotomensis and P. beringiana appeared in the early to late Miocene of northeastern Asia, while P. izumo and P. trapezoidis appeared in the middle to late Miocene of northeastern Asia and Alaska. Panomya nipponica, P. ampla, and P. norvegica appeared during the Plio–Pleistocene in northern Japan and Bering regions. All extant species evolved in the North Pacific; Panomya trapezoidis and P. norvegica extended their ranges to the North Atlantic in the middle Pliocene and early Pleistocene, respectively, and P. beringiana and P. ampla migrated into the Arctic Ocean in the late Pleistocene to Holocene.

The integration of Geographic Information System (GIS) methodology within a phylogenetic and statistical framework provides a background against which to evaluate the relationship between biogeographic changes and evolution in the fossil record. A case study based on patterns in Middle and Late Devonian phyllocarids (Crustacea) illustrates the usefulness of this integrated approach. Using a combined approach enhances determination of rates of biodiversity change and the relationship between biogeographic and evolutionary changes. Because the interaction between speciation and extinction rates fundamentally determines biodiversity dynamics, and speciation and extinction rates are influenced by the geographic ranges of component taxa, the relationship between biogeography and evolution is important. Furthermore, GIS makes it possible to quantify paleobiogeographic ranges.

Phylogenetic biogeography resolved patterns of both vicariance and geodispersal and revealed that range expansions were more abundant than range contractions in Devonian phyllocarids. In addition, statistical tests on GIS-constrained species ranges and evolutionary-rate data revealed a relationship between increasing species' ranges and increases in both speciation and extinction rates. Extinction rate, however, increased more rapidly than speciation rate in the phyllocarids. The pattern of extinction rate increasing faster than speciation rate in the phyllocarids may illuminate aspects of the Late Devonian biodiversity crisis in particular, and protracted biodiversity crises in general.

The recovery of well-preserved silicified larvae from the early Tournaisian of Montagne Noire, southern France, allows the first description of the early ontogeny of proetoid trilobites, survivors of the end-Devonian Hangenberg extinction event. The fauna comprises various taxa that can only partly and tentatively be assigned to the genera Liobolina, Diacoryphe, and Pedinocoryphe without specific attribution. The close resemblance of these larvae to previously described proetoid larvae from the Ordovician and Devonian emphasizes the ontogenetic homogeneity of this superfamily. Moreover, it supports the view that the Proetida is composed of two clades: the Aulacopleuroidea/Bathyuroidea group and the Proetoidea. The Carboniferous anaprotaspides exhibit an unusually wide size-range that may provide evidence of the acquisition of an extended planktonic period in the early ontogeny of at least some Carboniferous proetoids. This change in the ontogenetic strategy may have enabled proetoid trilobites to survive during the end-Devonian biocrises.

A relatively diverse chelicerate fauna has been detected in Early Devonian, Siegenian strata of the Westerwald area, Rhineland-Palatinate, Germany. The arachnids, comprising trigonotarbids and the oldest phalangiotarbids, are described and figured here along with the chasmataspidids. To accomodate the phalangiotarbid a new genus and species in the family Architarbidae, Devonotarbus hombachensis, is raised. Devonotarbus n. gen. is characterized by an approximately straight posterior carapace margin, abbreviated and undivided anterior tergites, a large sixth tergite, and fused posterior tergites. The chasmataspidid closely resembles Diploaspis casteri from the Emsian assemblage of Alken an der Mosel, but is readily discernible as a new species, D. muelleri, by a strong tuberculation of its dorsal integument. With only fragmentary opisthosomal remains available, the trigonotarbids cannot be placed in known taxa with any certainty at this time.

The xanthoid genus Xanthilites Bell, 1858 is herein restricted to contain only the type species X. bowerbanki and possibly a second species. Xanthilites sensu stricto, Pulalius, Tumidocarcinus, Paratumidocarcinus, and Baricarcinus are placed within the Tumidocarcinidae new family within the Xanthoidea. It is hypothesized that the Carpiliidae, Platyxanthidae, Tumidocarcinidae new family, Zanthopsidae, and at least some subfamilies of the Eriphiidae form a natural group and may belong to a discrete superfamily, based upon paleontological and neontological evidence. The earliest documented occurrence in the fossil record for the xanthoid Platyxanthidae is in Eocene rocks, with the referral herein of a fossil species to the family. The two related families, Eriphiidae and Platyxanthidae, are difficult to distinguish from one another in fossil specimens; diagnoses which take into account preservable characters are provided. Moreover, based upon morphological features the Eriphiidae as currently defined may comprise at least two families. Revision of Xanthilites has resulted in two new genera, Jakobsenius and Rocacarcinus, erected for Xanthilites? cretacea and X. gerthi respectively, both placed within the extinct Palaeoxanthopsidae. The common ancestor of at least some families currently referred to the Xanthoidea may lie within the Palaeoxanthopsidae, which may have embraced “pre-adapted survivor” taxa, surviving the end-Cretaceous extinction event. Goniocypoda tessieri is confirmed as a member of the Hexapodidae, extending the range of that family into the Cretaceous; however, the family is not a likely candidate for embracing the ancestral xanthoids. The illustrated specimen of Menippe frescoensis retains a barnacle epibiont, very rare in the fossil record of decapods.

The Mississippian ammonoids Kazakhstania mangeri new species, Muensteroceras cf. oweni (Hall, 1860), and Masonoceras kentuckiense Work and Manger, 2002 occur near the base of the Nancy Member of the Borden Formation in northeastern Kentucky. Associated conodonts indicate an early Osagean [Fern Glen or lower Burlington (Dolbee Creek Member) equivalent] age corresponding to the lower Ivorian Stage of the Belgian upper Tournaisian succession.

Fossilized argonaut egg cases have been recovered from marine siltstones of the late Miocene exposed around margins of the Los Angeles Basin, California. Low radial ribs on the thin, keelless, planispirally coiled egg cases suggest referring them to Mizuhobaris lepta new species. Occurrence of these egg cases in fine-grained Monterey Formation sediments with mesopelagic fish fossils, nannofossils, and Foraminifera indicate deposition in middle-to-upper bathyal depths. Argonaut egg cases have been described from Tertiary strata in Japan, New Zealand, Sumatra, and Europe, but this is the first report of fossilized argonaut egg cases from the Western Hemisphere.

Secretion of egg cases by argonauts probably developed during the Paleogene as a solution to problems of spawning encountered by octopi as they acquired an epipelagic, open-ocean habitat. Shape and sculpture of the egg cases represent responses to hydrodynamics rather than an inheritance from or copying of ectocochliate cephalopods. The cases may provide the eggs with protection from ultraviolet radiation present in the argonauts' near-surface habitat.

Restudy of two Early Silurian (Aeronian) stricklandioid species, Stricklandinia transversa Grabau, 1925 and Stricklandiella robusta Rong and Yang, 1981 from the Yichang area of South China, leads to the recognition of two new genera, Sinokulumbella and Sinostricklandiella. Two types of spondylia and four types of cardinalia are recognized for the Stricklandioidea and can be used for classification of the superfamily at the generic or even familial level. On the basis of these characters, five groups (typified by Stricklandia, Stricklandiella, Kulumbella, Microcardinalia, and Aenigmastrophia) can be recognized within the superfamily. Sinokulumbella n. gen., with a small, shallow, bowl-shaped spondylium and a pair of outer hinge plates that are discrete from the crura, is regarded to be affiliated with the Kulumbella group. Sinostricklandiella n. gen. has superimposed plicae and costae, although its internal structures are similar to the Stricklandiella group. A revised classification of stricklandioids implies that the Chinese pentamerides were characterized by strong provincialism during the early and middle Llandovery. This interpretation is supported further by the complete lack of true Stricklandia and Microcardinalia lineages in South China. Different stocks of stricklandioids in Baltica, Laurentia, South China, Siberia, and Kazakhstan may have experienced allopatric evolution, punctuated by several pulses of faunal migration or exchange between these paleoplates during the Llandovery. Evolution of the Stricklandia lineage is significantly different from that of Kulumbella and Sinokulumbella, particularly in that the outer plates disappeared earlier in the kulumbellids than in the stricklandiids.

Argenthina emilyae is a new genus and species of extinct muricid gastropods from the early Middle Miocene of southern Argentina. Most of its shell features are consistent with those of the Acanthina-clade of Thais-like ocenebrines, including a broad, rounded body whorl, a large aperture lacking ornamentation, and a short, open siphonal canal, although other characters are consistent with the Ocinebrina-like ocenebrines, such as the differentiation of axials into varices and intervaricals and complex spiral sculpture. This combination of traits is unique in the Ocenebrinae. It is not yet clear whether this new taxon represents an episode of morphological experimentation by a stem group of Thais-like ocenebrines resulting in convergence on the Ocinebrina-like shell form or an evolutionarily intermediate step between Thais-like and Ocinebrina-like ocenebrines. Intermediates are expected from previously published phylogenetic hypotheses for the Ocenebrinae that suggest Ocinebrina-like ocenebrines have evolved multiple times from Thais-like ocenebrines. Until now, however, such intermediates have not been reported from the fossil record.

The paraphyletic group Grylloblattida, formerly included in the Protorthoptera sensu lato, is of great importance for the phylogeny of some ‘polyneopterous’ orders, because it is currently assumed to contain the sister groups of modern Plecoptera (stoneflies) and Grylloblattodea. We present new discoveries and new observations and interpretations concerning this crucial assemblage. Lodevopterum angustus new genus and species and Depressopterum minutus new species are described from the Upper Permian of the Lodève Basin (Hérault, France). The ‘Grylloblattida’ from Commentry (Allier, France; Upper Carboniferous) are revised: the family Protoblattinidae Meunier, 1909a is restored after the redescription of the type species Protoblattina bouvieri Meunier, 1909a; the family Stenoneuritidae Lameere, 1917 is revised; Palaeocixius fayoli Handlirsch, 1906b and Protoblattina giardi Meunier, 1921 are synonymized with Palaeocixius antiquus Brongniart, 1893, followed by a discussion on the possible familial attributions of this genus. The affinities of the poorly known family Protoperlidae Brongniart, 1885a are discussed after a critical compilation of the available data, i.e., Protoperla boltoni Lameere, 1917 is considered as Grylloblattida incertae sedis and Polyetes elegantissima Meunier, 1921 is transferred into Laurentiaupterum new genus and assigned to Paraphenopteridae new family. Close phylogenetic relationship of Atactophlebia termitoides Martynov, 1928 (Tikhiye Gory, Tatarian Republic, Russia; Upper Permian) and Pinidelia sukatshevae Storozhenko, 1994 (Tyulkino, Perm region, Russia; Upper Permian) is based on a new interpretation of their forewing venation. The recent taxonomy and phylogeny of the Grylloblattida proposed by Storozhenko (1998, 2002) are refuted. The current concepts of Protorthoptera, Plecopteroid Assemblage, and Grylloblattida are compared.

New species of Early Ordovician bivalves and rostroconchs from the northwestern Argentina basin are described. Bivalves include the following species: Cienagomya bidentata new genus and species, Goniophorina tenuicostata, Lipanella purmamarcensis new genus and species, Ucumaropsis lermaensis new genus and species, and Coxiconchia babini new species. Among rostroconchs, Ribeiria pojetai new species is recognized. Cienagomya bidentata (late Tremadoc–early Arenig) may represent a phylogenetic link between the families Intihuarellidae and Cycloconchidae. The new family Lipanellidae is erected to include Lipanella n. gen. Recognition of Ucumaropsis n. gen. in the early Arenig attests to the important radiation of the Anomalodesmata in northwestern Argentina.

Isolated marginal tooth crowns of the early Campanian mosasaur Hainosaurus Dollo, 1885, from the Kristianstad Basin and the Vomb Trough, southern Sweden, are described and illustrated. The teeth have been collected from a narrow stratigraphic interval corresponding to the highest belemnite zone in the lower part of the European two-fold division of the Campanian stage. A reexamination of dental and skeletal characters in two alleged species of Hainosaurus, ‘H.’ pembinensis Nicholls, 1988 and ‘H.’ gaudryi (Thévenin, 1896), and detailed comparisons with the corresponding elements in H. bernardi Dollo, 1885 and Tylosaurus proriger (Cope, 1869a), strongly indicate that ‘H.’ pembinensis and ‘H.’ gaudryi are both Tylosaurus Marsh, 1872. Diagnostic features of Hainosaurus include a very small infrastapedial process on the quadrate (conspicuous protuberance in Tylosaurus), flattened, symmetrically bicarinate marginal teeth (asymmetric and conical in Tylosaurus), short and wide pygal centra, and anteriorly situated intermediate caudal vertebral centra with dorsoventrally thin transverse processes (markedly triangular centra and thick processes in Tylosaurus).

Species of Trophon Montfort, 1810 are well known from Tertiary rocks exposed over a wide area of Patagonia. All nominal species referable to the genus were revised and, where necessary, synonymized. Valid species were redescribed and reillustrated, based on type material and additional material collected at other localities ranging from Península Valdés to south of the mouth of the Santa Cruz River (along the Atlantic coast of Patagonia) to Lake Pueyrredón (along the foothills of the Andes). Of the 17 nominal species, only six are considered valid, i.e., Trophon sowerbyi new name (replacement for Fusus patagonicus Sowerby, 1846 in Darwin non d'Orbigny), Trophon santacruzensis Ihering, 1897, Trophon camachoi new species, Trophon leanzai Brunet, 1997, Trophon contortus Brunet, 1997, and Trophon inornatus Pilsbry, 1897.

The following differences were found between the members of the cornulitids, Cornulites and Conchicolites. Both genera have egg-shaped embryonic shells, which presumably calcified after the settling of Iarva to the substrate, but the embryonic shells in Cornulites are larger than in Conchicolites. Cornulites has a regularly foliated shell ultrastructure and pseudopuncta, whereas the shell ultrastructure in Conchicolites is prismatic. In Cornulites the outer part of the shell contains numerous vesicular cavities that were never observed to cross the interspaces of the surface annulae, indicating cyclic shell secretion. In several species the vesicles are internally coated by calcitic lamellae that are oriented subparallel to the shell surface. In Conchicolites the vesicular shell structure is absent and the calcitic prisms are deposited at the shell aperture more or less at right angles to the longitudinal shell axis. The function of the surface annulae in Cornulites and transverse ridges in Conchicolites may have been to strengthen the shell wall and protect it against longitudinally developing cracks. Vesicular structure in Cornulites seems to have provided a stronger shell for less material and smaller cost of energy. Differences between Cornulites and Conchicolites indicate that the two taxa were probably unrelated and that cornulitids may be a polyphyletic taxon. Cornulites shares the most characters with the lophoporates and tentaculitids. Biological affinities of Conchicolites are controversial, and its morphologic features need further revision to affiliate this group with certainty to any extant animal phylum.

A detailed morphometric approach applied to the diversity (interspecific variation)/disparity (intraspecific range of variation) was developed. It was based on outline analysis, and it was applied to 41 cross sections of Kosmoceras from the Upper Callovian of eastern France (Prusly). The cross sections represent an excellent basis for evaluation of the global shape of the shell: the main morphologic descriptors include the proportion of umbilical diameter/conch diameter and the thickness of the whorl; they also indirectly describe the ornament that influences the aspect of the whorl section. This analysis was conducted to quantify the size and shape variations and to determine the relations among some of the ‘morphological species’ defined by Tintant: K. bizeti, K. fibuliferum, K. phaienum? and K. interpositum? Numerous analyzed individuals may not belong to these categories.

The results suggest that despite a wide range of variability four main morphotypes can be ascribed a probable taxonomic status, whose mean representatives can be properly assigned to Tintant's four ‘species.’ Moreover, three of them could constitute a morphological series, continuously related through ontogeny. The fourth (K. interpositum) may be an independent species, rarely recovered in the studied area.

Five species of aulacopleurid trilobites occur in rich, silicified trilobite faunas from the Upper Ordovician of Virginia: Harpidella triloba (Hu, 1975a), Strasburgaspis cona (Hu, 1971), and Strasburgaspis? n. sp. A, all from the Turinian Edinburg Formation, Harpidella whittingtoni new species, from the overlying Turinian Oranda Formation, and Harpidella evitti new species, from the Chatfieldian Martinsburg Formation. The species of Harpidella, similar to other sets of congeneric taxa known from the formations, are subtly but pervasively differentiated. In addition to qualitative differentia such as the expression of the eye socle and of pygidial tubercle rows, the species are shown to differ in cranidial and librigenal shape via landmark-based geometric morphometric analysis. The genus Strasburgaspis (type species S. cona) is new. It is assigned to Aulacopleuridae on the basis of its micropygous morphology, but it shares potential apomorphies with Brachymetopidae and could prove to be the most plesiomorphic representative of that family.