Morphometric analyses of shell morphology in the Pennsylvanian nautiloid Metacoceras mcchesneyi Murphy, 1970 (Cephalopoda, Mollusca) recovered from coal mines in Madison Township, Columbiana County, Ohio, USA, reveal the ontogenetic change from hatching to maturity as well as intra-specific variation of shell morphology. The shell shape of M. mcchesneyi has isometric relationships, and the umbilicus diameter between umbilical shoulders has a positive allometric relationship with shell diameter. These show that the relative whorl shape was constant through the ontogeny, but the umbilicus became relatively broader with growth. The siphuncle position moved from a ventro-central position toward the center with growth until 420° of the total rotational angle had been attained. A constriction was recognized on the early whorl at 9.5 mm in shell diameter, and the interval angles of succeeding septa were changed at the 5th septum, indicating that hatching occurred at this diameter. The ventral apertural wall, the disappearance of ornamentation toward the last preserved aperture, and the last whorl separating from the previous whorl indicate that M. mcchesneyi attained maturity at ca. 70 mm in shell diameter. Most characteristics of shell morphology in M. mcchesneyi (the relative shell shape and ornamentation through ontogeny) are comparable to those in modern and younger fossil nautilids, irrespective of taxonomy and age, supporting the conclusion that evolutionary rates of shell morphology are conservative in nautilid history.

Diverse and abundant fossil taxa have been described in the lower Cambrian Shipai Formation in the Three Gorges area of Hubei Province, South China, but the taxonomy and diversity of the co-occurring brachiopod fauna are still far from clear. Here we describe the brachiopod fauna recovered from the Shipai Formation in the Three Gorges area of South China, including representatives of the subphylum Linguliformea: linguloids (Lingulellotreta ergalievi, Eoobolus malongensis, and Neobolidae gen. indet. sp. indet.), and an acrotretoid (Linnarssonia sapushanensis); and representatives from the subphylum Rhynchonelliformea: the calcareous-shelled Kutorginates (Kutorgina sinensis, Kutorgina sp., and Nisusia liantuoensis). This brachiopod assemblage and the first occurrence of Linnarssonia sapushanensis shell beds permit correlation of the Shipai Formation in the Three Gorges area of Hubei Province with the Stage 4 Wulongqing Formation in the Wuding area of eastern Yunnan. This correlation is further strengthened by the first appearance datum (FAD) of the rhynchonelliform brachiopod Nisusia in the upper silty mudstone of both the Shipai and Wulongqing formations. The new well-preserved material, derived from siliciclastic rocks, also gives critical new insights into the fine shell structure of L. sapushanensis. Microstructural studies on micromorphic acrotretoids (like Linnarssonia) have previously been restricted to fossils that were acid-etched from limestones. This is the first study to carry out detailed comparative ultrastructural studies on acrotretoid shells preserved in siliciclastic rocks. This work reveals a hollow tube and solid column microstructure in the acrotretoid shells from the Shipai Formation, which is likely to be equivalent of traditional column and central canal observed in shells dissolved from limestones.

Notidanodon lanceolatus Woodward is reported from Late Aptian strata of northern California. This specimen, the oldest fossil cow shark (Hexanchidae) in the New World, greatly extends the geographic distribution of this species and confirms the eurytopic distribution of this genus. We suggest that cow shark teeth evolve in an orderly sequence in which the mesial edge of the tooth is at first smooth (Notidanus muensteri), then serrate (Notidanus serratus, Notorynchus aptiensis), and finally dentate (Notidanodon lanceolatus).

A new full description of the bivalve Shikamaia akasakaensis Ozaki (genotype species of Shikamaia) is presented, providing the first documentation of its hinge and ligament, and resolving many uncertainties about Shikamaia, the first described genus of the Permian bivalve family Alatoconchidae. The genus Shikamaia has a unique ligament, modified from typical duplivincular ligaments in occupying only half of the cardinal area, and having ligament sheets that extend themselves towards the beak with continued growth. This ligament is strikingly different from the ligaments of other alatoconchid genera. All alatoconchids are believed to have a common ancestry, but the magnitude of difference in their hinges warrants dividing the family into two subfamilies. The subfamily Saikraconchinae is erected new.

A Lower Silurian (Llandovery) shelly fauna is described; the first from the Iberian Peninsula. It is dated as late Llandovery (early Telychian) by Stricklandia aff. laevis and is overlain by a late Telychian conodont fauna. The fauna is from the volcaniclastic El Castro Formation, Viodo Limestone Member, north of Viodo, Asturias, northern Spain. There are seven common and five rarer brachiopods, including the new taxa Asturorthis sarreoensis new genus and species, Mendacella cantabrica new species, Katastrophomena truyolsi new species, Viodostrophia alcaldei new genus and species, Stegerhynchus juliverti new species, and Fenestrirostra? viodoensis new species.

The St. Clair Limestone and Clarita Formation contain large, Upper Silurian (Wenlockian) brachiopod faunas. The St. Clair Limestone crops out in two areas in north-central Arkansas; one is the type area near Batesville, in parts of Independence, Stone, and Izard Counties, the other is near Gilbert, Searcy County. The Clarita Formation, Fitzhugh Member, crops out in the Arbuckle Mountain region and Criner Hills of south-central Oklahoma. The articulate brachiopod fauna of the St. Clair Limestone comprises 45 species and subspecies referred to 35 genera and subgenera, and that of the Clarita Formation, Fitzhugh Member, comprises 23 species and subspecies referred to 22 genera and subgenera. The combined St. Clair-Clarita fauna totals 51 species and subspecies, of which 17 are new; 40 genera and subgenera are represented, of which 9 are new: Orthostrophella, Onychotreta (Eilotreta), Onychotreta (Lissotreta), Placotriplesia, Boucotides, Leangella (Opikella), Virginiata, Dicamaropsis, and Homoeospirella. The faunas of the St. Clair and Clarita are remarkably similar; all but six of the Clarita species are present in the St. Clair, and the two formations are closely related in age. Strata of this age are probably widely distributed in the Midcontinent area of the United States, although the brachiopod evidence for this is meager. The generic suite represented in the St. Clair-Clarita brachiopod faunas is similar to that of the Wenlock of Great Britain and the Slite and Mulde Marlstones of Gotland; the stage of development represented by the St. Clair species of Dicoelosia is also similar to that of D. biloba from the Wenlock Limestone and Slite and Mulde Marlstones. The St. Clair-Clarita brachiopod fauna does not show any marked similarity to brachiopod faunas known to be in the Silurian of Bohemia, and, in fact, correlation with the Czechoslovakian Silurian section is at present uncertain.

During the Pliocene, the diversification of the tribes Lamini and Camelini of the Family Camelidae took place in most of North America, but at present in Mexico the systematics of Pliocene Camelidae are poorly known. Fossil material described in this paper was recovered from Blancan I and Blancan III age floodplain and point bar deposits of the San Miguel de Allende basin, Guanajuato state, central Mexico, which approximately spans a time frame from 4.7 to 3.0 Ma. The identified taxa include the lamines Hemiauchenia blancoensis (Meade) 1945, Hemiauchenia gracilis Meachen, 2005, Blancocamelus meadei Dalquest, 1975 and Camelops sp., while the camelines are represented by Megatylopus sp. The records of H. gracilis and B. meadei in the Pliocene of central Mexico are the oldest in North America. Previous studies of the probable feeding strategies of these taxa indicate that they were browsers or browser-like intermediate feeders and just one was an intermediate feeder. The records of these species in the Early Blancan of Guanajuato extend their geographic distribution from the southern USA to central Mexico.

The analysis of trace fossils usually is performed qualitatively, which makes comparing trace fossils from different units less objective than quantitative approaches. Quantifying the shape of trace fossils enables scientists to compare trace fossils described by different people with greater precision and accuracy. This paper describes several methods for quantifying invertebrate trace fossils, including morphology dependent methods (motility index, mesh size, topology, tortuosity, branching angle, and the number of cell sides) and morphology independent methods (fractal analysis, burrow area shape, and occupied space percentage (OSP)). These tools were performed on a select group of graphoglyptid trace fossils, highlighting the benefits and flaws of each analytical approach. Combined together, these methods allow for more objective comparisons between different trace fossils.

This contribution presents the first description of crinoids from western margin of Parnaíba Basin. It also presents their first description in the Pimenteira Formation (Devonian of the Parnaíba Basin, state of Tocantins, Brazil). The material is represented by hundreds of columnals, pluricolumnals, as well as isolated calyx plates. Columnal and pluricolumnal morphology allowed the identification of Laudonomphalus aff. L. tuberosus, and Exaesiodiscus dimerocrinosus n. sp. Based upon calyx plate morphology a new Rhodocrinitidae species was erected, Monstrocrinus incognitus n. sp. The genera Exaesiodiscus, Laudonomphalus, and Monstrocrinus were previously described from the Devonian of Amazonas Basin. Exaesiodiscus dimerocrinosus is also identified from the northwest margin of Paraná Basin. The Monstrocrinus occurrence is rare in the Middle Devonian, until now known in Germany, Spain, and Algeria Lower Devonian (upper Emsian) and only in northern Brazil in the Middle Devonian (Eifelian.) These facts provide valuable arguments for paleogeographic interpretations regarding the pattern of distribution of invertebrates in this region of Gondwana and suggest potential migration routes in northern Gondwana during the Devonian.

Certain groups of living Chlorophyta (green algae) have thalli made up of long, tubular cells with many nuclei and many plastids (Tappan, 1980; Bold and Wynne, 1985). The only cross walls in these coenocytes are those that isolate the gamete-producing structures. As the coenocytes approach the edges of the thallus, they branch, generally dichotomously, one or more times and eventually terminate in clavate or bulbous segments called utricles (Latin for small bag or bottle). Thus, the utricles are the termini of coenocytes that occur along the surface of the thallus and interface with the environment. Utricles have been figured in many descriptions and illustrations of such calcified genera as Halimeda (Wray, 1977) and such noncalcareous genera as Codium (Bold and Wynne, 1985). Because of the easily recognized distinction between the parts of the coenocytes, the thallus in cross section consists of a cortex occupied by the utricles and their contiguous segments and a medulla occupied by the long tubular portions of the cell (Figure 1).

A true interreef crinoid fauna lacking components of reefal facies is reported from the Ludlovian of the Mississinewa Shale Member of the Wabash Formation in northern Indiana. The Mississinewa facies that contains this fauna is a dolomitic siltstone or a silty dolomite. The crinoid association reported is composed entirely of new species and is different from other reef and reef-associated, interreef, and non-reef crinoid associations. New species described, herein, include the following: Dimerocrinites (Eucrinus) ankylos n. sp., Periechocrinus shaveri n. sp., Bohemicocrinus? occidens n. sp., Macrostylocrinus styo n. sp., M. homalos n. sp., Gissocrinus hypselos n. sp., and Dendrocrinus diaphoros n. sp. This may be the first occurrence of Bohemicocrinus from outside Bohemia.

Pliocene to Holocene deposits of the U.S. Atlantic Coastal Plain from Maryland to Georgia are divided into four stages and four substages using molluscan biostratigraphic data. These divisions are the Wiltonian and Burwellian Stages (early Pliocene), Gouldian and Windyan Substages of the Colerainian Stage (late Pliocene to early Pleistocene), and Myrtlean and Yongesian Substages of the Longian Stage (late Pleistocene to Holocene). These stages may be recognized from Florida to as far north as Massachusetts and will facilitate correlation with other regions.

Two new records of gomphotheriid proboscideans, one identified as Rhynchotherium and the other as Cuvieronius, are reported in México. Both records are in the southwesternmost points of their known distributional range.

The remains of both genera consist of molars and tusks. Their measurements were compared with data available from the literature and collection specimens. The molar index of Rhynchotherium shows statistical differences between m2 and M2, and m3 and M3. However, differences between the m3 from both genera are not statistically significant, despite slight morphological differences.

This suggests that metric and morphological information should be included for a reliable identification of isolated molars and, if available, any other data of the associated tusk.

All known records relating to both genera suggest that they found southwestern México favorable for use as a dispersal corridor to South America, likely due to the region's tropical or subtropical climate. However, some distributional gaps in central México need to be resolved for Rhynchotherium. There are also important populations of Cuvieronius in central México, and preliminary information suggests that they occupied at least parts of eastern México, as well.

Lack of an adequately calibrated Devonian time scale precludes satisfactory comparisons of Recent and Devonian bryozoan diversities. Nevertheless, Devonian bryozoans apparently are 3–100 times less diverse than Recent bryozoans. This variation is a function of how Devonian time is divided (whole period, stages, per million years) as well as the diverse skeletal architecture of cheilostome bryozoans, the most abundant Recent bryozoan order.

The Givetian has the largest specific, generic, and familial diversity of any Devonian stage and the drop in bryozoan diversity from the Givetian to the Frasnian is greater than the rise or fall of diversity between any other adjacent stages. Diversity hardly changes among bryozoans across the Frasnian–Famennian boundary. Among bryozoans the Givetian–Frasnian extinction was a major event.

Devonian taxonomic diversity is less than nomenclatorial diversity, although both exhibit the same trends from stage to stage during the Devonian. The amount of difference between the two measures of diversity is probably a reflection of the intensity of research on Devonian Bryozoa, especially revisionary studies of previously described faunas. Monographic bursts in diversity are present and are a measure of the episodic character of taxonomic studies on less popular phyla. Examination of the literature commonly provides a finer stratigraphic resolution than indicated in compilations such as the Zoological Record.

Although some significant areas of the exposed continents have not received adequate study, Devonian bryozoans show marked geographic changes in diversity that can not be ascribed entirely to lack of study.

In the Recent biota, species of the hipponicid gastropod genus Sabia that excavate characteristic pits on the outer surfaces of shells of reef-dwelling gastropods and hermit crabs occur only in the tropical Indo-West Pacific region and in adjacent warm-temperate parts of Japan and Australia. I report the discovery of Sabia pits in reef-associated gastropod shells from the Cercado (late Miocene) and Gurabo (early Pliocene) Formations of the Dominican Republic. The likely culprit was Hipponix otiosa Pilsbry and Johnson, 1917, a species here reassigned to Sabia Gray, 1840. Pliocene extinction, which was far more severe in the Caribbean and elsewhere in the western Atlantic than in the Indo-West Pacific, selectively eliminated Sabia and its commensalism from Atlantic reef ecosystems. This case is one of several examples indicating the vulnerability of specialized associations to extinction-causing disturbances.

The Marginellidae Fleming and the Cystiscidae Stimpson, herein collectively referred to as marginelliform gastropods, are convergent families of thermophilic marine gastropods. Shallow-water marginelliform gastropods are found in the Ibero-Moroccan Gulf and Mediterranean, diversity rapidly increasing towards tropical West Africa. Surprisingly, in the tropical and subtropical European Miocene fossil record, marginelliform genera of tropical affinity such as Persicula Schumacher and Prunum Herrmannsen, occurring today in West Africa, are altogether missing. Others, such as Marginella Lamarck, are present only in the southwestern Iberian and Mediterranean Neogene record. This work describes the marginelliform gastropods from the Atlantic Iberian Neogene. Ten species are recorded, of which three are new, Persicula mikhailovae n. sp., Gibberula costae n. sp., and Gibberula brebioni n. sp. This study shows that Gibberula Swainson and Volvarina Hinds have been present in Europe since the Eocene. Marginella may have originated in southern Africa and migrated north to Europe in the Miocene, never extending further north than west central Portugal. Persicula and Prunum probably originated in the Caribbean and migrated east during the Pliocene, following closure of the Central American Seaway. The colonization of the Pliocene European Atlantic coast by gastropods of these genera was selective, only where high sea-water temperature and high productivity were combined. These findings suggest that post-Messinian recolonization of the Mediterranean during the Pliocene was a complex process, involving colonization by groups originating in various regions of the Atlantic, including Europe, Africa and the Americas.

Recent collecting provided fossil chitons (Mollusca, Polyplacophora) from upper Eocene to lower Oligocene deposits of Washington State, U.S.A. The study material consists of 140 valves from six localities in the Quimper, Makah, Lincoln Creek, Crescent and Gries Ranch formations. The material is mostly incomplete or very fragmented and/or worn so that a precise appreciation of diagnostic features has been in many cases difficult if not impossible. Fourteen species were identified, seven are described as new: Lepidopleurus propecajetanus n. sp., Leptochiton sp., Ischnochiton goederti n. sp., Ischnochiton? sp. A, Ischnochiton? sp. B, Stenoplax quimperensis n. sp., Stenoplax sp. A, Stenoplax sp. B, Lepidozona cowlitzensis n. sp., Lepidochitona lioplax (Berry, 1922), Lepidochitona washingtonensis n. sp., Lepidochitona squiresi n. sp., Lepidochitona sp. and Craspedochiton eernissei n. sp. The only species previously described from the study area is Lepidochitona lioplax and it is also the most common chiton in the study material (67% of the total). No species other than L. lioplax has been found in more than one locality. In four of these localities only a single species has been collected. The basal Lincoln Creek Formation at the Porter Creek site supplied the richest and most diverse chiton assemblage with seven species and 86% of the valves. The discovery and formal identification of such a diverse Paleogene fauna from the northeastern Pacific provides a comparative base for a better appreciation of Polyplacophora biogeography and evolution.

A new genus and species of the Elcanidae (Orthoptera, Elcanoidea), Cascadelcana virginiana n. gen. n. sp., is described based on a forewing specimen from the Upper Triassic (Norian) Cow Branch Formation in the Solite Quarry Lagerstätte near the North Carolina-Virginia boundary, USA. It is distinguished from other elcanid species by its RP+MA1 with six branches, M with two branches before stem MA1 fused with RP, and short CuA almost vertical against the posterior margin. This fossil represents the earliest definitive record of the family Elcanidae and the first orthopteran described from the Triassic of North America. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses show that the veins and a pterostigma-like structure on the wing of C. virginiana n. gen. n. sp. are preserved as carbonaceous compressions. The presence of a pterostigma-like structure in elcanids indicates that they may have evolved a particular flight mechanism distinct from those of other orthopterans.

UUID: http://zoobank.org/49526c99-5da4-48e3-ba6e-7018b8f9b1ae

New material from the Famennian of Morocco in the southern Maider comprises chondrichthyan teeth (Thrinacodus, Cobelodus, Denaea, Stethacanthus), actinopterygian remains (scales, teeth and hemilepidotrichium) and one acanthodian scale. The absence of crushing teeth suggests deeper water environments for the Maider Basin than the Tafilalt Basin. Vertebrate microremains from the Famennian of Sardinia, including Siamodus and Jalodus teeth, are illustrated and described. Ichthyofaunal relationships of the North Gondwanan platform during the Famennian are examined.

Fossil sharks are represented primarily by isolated teeth. Teeth are usually used for classification of extinct sharks, but their vertebrae may provide interesting paleoecological and taphonomical information even if not in association with teeth (e.g., Lucas et al., 1985; Gottfried, 1995). In this paper, I describe an isolated centrum of a shark vertebra from the Lower Cretaceous Kiowa Shale in Kansas, housed in the University of Kansas, Museum of Natural History (KUVP), Lawrence. A precise taxonomic assignment for this Kiowa shark is difficult because of its isolated occurrence, lack of large comparative collections of fossil shark vertebrae found in association with teeth, and poorly known morphological variation of fossil shark vertebrae. However, the specimen is noteworthy, because it is the largest Mesozoic shark vertebra known to date.