Fourteen new species and six new genera of the molluscan class Monoplacophora are described from the Upper Cambrian Potosi and Eminence formations and the Lower Ordovician Gasconade Formation of the Ozark Uplift of Missouri and some new biostratigraphic horizons are introduced. A new superfamily, the Hypseloconellacea nom. trans. Knight, 1956, and a new family, the Shelbyoceridae, are named. The genus Proplina is represented by five new species: P. inflatus, P. suttoni from the Cambrian Potosi Formation, P. arcua from the Cambrian Eminence Formation and P. meramecensis and P. sibeliusi from the Lower Ordovician Gasconade Formation. A new genus and species in the subfamily Proplininae, Ozarkplina meramecensis, is described from the Upper Cambrian Eminence Formation. Four new monoplacophoran genera in the superfamily Hypseloconellacea and their species are described, including: Cambrioconus expansus, Orthoconus striatus, Cornuella parva from the Eminence Formation, and Gasconadeoconus ponderosa, G. waynesvillensis, G. expansus from the Gasconade Formation. A new genus in the new family Shelbyoceridae, Archeoconus missourensis, is described from the Eminence Formation and a new species of Shelbyoceras, S. bigpineyensis, is described from the Gasconade Formation.

Mineralogical and microstructural analyses of Quenstedtoceras shells (Callovian, Poland) show that the outer shell material is preserved as nacreous aragonite, while the septal material shows different degrees of alteration. The septa in part are pyritized or show signs of cementation by equant/acicular calcite cement; paleoenvironmental interpretation of the least-altered outer shell material using the Sr/Na ratio suggests that the shell material was deposited in seawater which had a salinity of about 33 ppt and a range of about 32–35 ppt. Other data, such as Mn and Fe, imply that the oxygen level of the seawater was normal. The paleotemperature, using δ18O values with a salinity correction, was calculated to be about 11.0–14.5°C with an average water temperature of about 12.5°C. These paleoenvironmental parameters, in part, account for the faunal character of the Boreal Realm of the Jurassic.

Exuviae comprising immature growth stages allow the tracing of morphological and morphogenetical features of the reduced-eyed phacopid species Plagiolaria poothaii Kobayashi and Hamada, 1968, from the Early Devonian of Satun Province, southern Thailand. Biometric and morphometric approaches have been used to characterize the shape changes. This is the fourth phacopid genus for which ontogenetic information is known. Ontogenetic features of this species are generally similar to those of Phacops and Weyerites. However, the ankylosis of the facial sutures occurs at the end of the meraspid period, later than in Phacops, and this is probably a derived character.

Diameter, dip and orientation of burrows of the ghost crab Ocypode quadrata (Fabricius) were measured in back-beach areas: dune faces, dune crests, swales, blowouts and washover fans. Slope direction of the substrate at each burrow site was also measured. Results support three conclusions. First, burrow diameter increases landward. Second, burrow dip is related more to topography than to distance from shoreline; burrows dip more steeply in flatter areas (swales, blowouts, washovers). Third, a causal relationship exists between burrow orientation (as measured by the direction in which apertures point) and substrate slope; contrary to previous conclusions, burrow orientation is unrelated to shoreline direction. Burrow apertures simply point in the same direction as substrate slopes. In fact, on landward faces of dunes, burrow apertures point away from shoreline.

Remingtonocetidae are Eocene archaeocetes that represent a unique experiment in cetacean evolution. They possess long narrow skulls, long necks, fused sacra, and robust hind limbs. Previously described remingtonocetids are known from middle Eocene Lutetian strata in Pakistan and India. Here we describe a new remingtonocetid, Rayanistes afer, n. gen. n. sp., recovered from a middle to late Lutetian interval of the Midawara Formation in Egypt. The holotype preserves a sacrum with four vertebral centra; several lumbar and caudal vertebrae; an innominate with a complete ilium, ischium, and acetabulum; and a nearly complete femur. The ilium and ischium of Rayanistes are bladelike, rising sharply from the body of the innominate anterior and posterior to the acetabulum, and the acetabular notch is narrow. These features are diagnostic of Remingtonocetidae, but their development also shows that Rayanistes had a specialized mode of locomotion. The expanded ischium is larger than that of any other archaeocete, supporting musculature for powerful retraction of the hind limbs during swimming. Posteriorly angled neural spines on lumbar vertebrae and other features indicate increased passive flexibility of the lumbus. Rayanistes probably used its enhanced lumbar flexibility to increase the length of the power stroke during pelvic paddling. Recovery of a remingtonocetid in Egypt broadens the distribution of Remingtonocetidae and shows that protocetids were not the only semiaquatic archaeocetes capable of dispersal across the southern Tethys Sea.

The trace-fossil name Tubotomaculum has been extensively used to refer to spindle-shaped pellet-filled tubes present in Upper Cretaceous to Miocene deep-marine deposits of the western Mediterranean region. However, it has never been formally diagnosed, and accordingly it was regarded as a nomen nudum. In this paper, we formally introduce the ichnogenus Tubotomaculum, including the new ichnospecies Tubotomaculum mediterranensis. Bioglyphs, represented by scratch traces that may be present on the basal and lateral surfaces of the structure, suggesting production by crustaceans. The functional meaning of these structures challenges the simple model of a mining strategy. Instead, the storing of pellets to use them as a bacteria-enriched resource during times when organic detritus was scarce is suggested. The association with chemoautothrophic bacteria in modern analogs of Tubotomaculum provides a crucial piece of evidence to support the cache model. Integration of information from modern environments and the fossil record points to a connection between Tubotomaculum, mud volcanism, fluid venting, and hydrocarbon seeps. The presence of bioglyphs suggests firmgrounds that may have resulted from bottom current scouring of the sea sediment, leading to erosional exhumation of previously buried compacted sediment, which was therefore available for colonization by the infauna. However, an alternative scenario involves enriched fluids related to mud-volcanism resulting in reducing conditions that favored carbonate precipitation and nodule formation just a few centimeters below the sediment-water interface.

The mechanism that guides the formation of exceptionally preserved fossils with soft tissues variously displayed is a paramount challenge to paleontology. The key question for exceptional preservation is the nature of the slowdown of decay and acceleration of soft tissue mineralization. Here we report the experimental formation of subfossils of the brine shrimp Artemia salina (Crustacea, Branchiopoda), which were produced during 14 months of aging in a kaolinite clay sediment. EDS/SEM elemental analyses showed that the subfossils were preserved as thin clay-organic replicas that displayed fine anatomical details. Decomposition in the clay-colloidal solution established highly heterogeneous acidic conditions, with the lowest pH typically found in the vicinity of the buried organisms, and visually manifested in patchy coloration of the sediment. Elevated acidity is likely what ultimately slowed the decay. An acidic environment increases the rate of clay destruction and, consequently, the diffusion rate decline. As a result, the acidic products quickly accumulate around a buried body; this in turn inhibits bacterial proliferation, accelerates the acidic hydrolysis of clay and, accordingly, the release of tanning and mineralizing agents. The subfossils remained stable under experimental high pressure and temperature. These model subfossils exhibit features that are typical of some Lagerstätten fossils preserved in fine-grained sediments.

The discovery of a new locality yielding giant Guadalupian (Lower Permian) fusulinids in east-central Alaska extends the range of these forms much farther north than previously known, and into a tectonostratigraphic terrane from which they previously had not been reported. The number of areas from which giant parafusulinids are known in North America is thus raised to eight. Three of these localities are in rocks that previously had been referred to the allochthonous McCloud belt arc, and one, West Texas, is known to have been part of Paleozoic North America. Comparison of species from all areas suggests that there are two closely related species groups: one represented in Texas and Coahuila, and the other represented in Sonora, northern California, northeastern Washington, southern and northern British Columbia, Alaska, and apparently in Texas. These groups may differ because they are of slightly different ages or because interchange between the faunas of Texas–Coahuila area and the other regions was somewhat inhibited during the Early Permian.

Notobatrachus degiustoi is the most completely known Jurassic frog and has been recorded in many outcrops of the La Matilde Formation of the Deseado Massif area in southern Patagonia. Herein, we erect a new species of the genus based on partially articulated remains collected from the Callovian Las Chacritas Member of the Cañadón Asfalto Formation, about 500 km northwest of the northern limit of the known geographical distribution of N. degiustoi. The new species differs from the latter in having a maxilla with a distinct pterygoid process and lacking teeth at least along the posterior two-thirds of its length, and a complete maxillary arch. We also provide an expanded diagnosis of Notobatrachus. This finding adds to our understanding of the early diversification of frogs.

Very well preserved specimens of a macruran decapod from the Lower (Lacustrine) Member of the Ñirihuau Formation, northwestern Patagonia, Argentina, permitted description of Lammuastacus longirostris, a new genus and species of Parastacidae. The sedimentological and paleontological evidences provided by the faunal assemblage indicate a freshwater environment. This is the first certain record of a fossil Parastacidae from Tertiary deposits, most probably Oligocene. The fossil material shows similarities with Geocharax, the extant Australian genus considered to retain many primitive characters, and other related genera from New Zealand and Chile.

A well-preserved and moderately diverse acritarch assemblage was recovered from the upper Ordovician Maquoketa Shale of northeastern Missouri. Based on graptolite and conodont evidence, the Maquoketa in northeastern Missouri is considered Richmondian (=Ashgill) in age.

The acritarch assemblage comprises 28 species, distributed among 17 genera including two new genera, Caelatosphaera and Stictosoma. There are 11 new species, Baltisphaeridium adiastaltum, Caelatosphaera verminosa (type species), Dorsennidium undosum, Elektoriskos aktinotos, Lophosphaeridium acinatum, L. varum, Micrhystridium hirticulum, M. prolixum, Peteinosphaeridium accinctulum, P. septuosum, and Stictosoma gemmata (type species); together with two species similar to previously named species and three species left in open nomenclature. Cosmopolitan and stratigraphically important species identified include Baltisphaeridium perclarum Loeblich and Tappan, 1978; Cheleutochroa sp. cf. C. diaphorosa Turner, 1984; Dorsennidium hamii (Loeblich, 1970) Sarjeant and Stancliffe, 1994; Excultibrachium concinnum Loeblich and Tappan, 1978; Orthosphaeridium insculptum Loeblich, 1970; O. rectangulare (Eisenack, 1963) Eisenack, 1968, and Villosacapsula setosapellicula (Loeblich, 1970) Loeblich and Tappan, 1976. Polygonium gracile Vavrdová, 1966 emend. Sarjeant and Stancliffe, 1994 and Micrhystridium hirticulum new species dominate the assemblage, followed by Dorsennidium undosum new species, Baltisphaeridium oligopsakium Loeblich and Tappan, 1978, Veryhachium sp. cf. V. oklahomense Loeblich, 1970, Peteinosphaeridium accinctulum new species, and Lophosphaeridium acinatum new species. Additionally, the palynoflora contains chitinozoans, scolecodonts, cryptospores, and the enigmatic palynomorph Gloeocapsomorpha prisca Zalessky, 1917 emend. Foster, Reed, and Wicander, 1989.

Paleontologic-palynologic and sedimentologic evidence indicates that the Maquoketa Shale at the two studied localities accumulated under low energy, somewhat offshore, and unrestricted marine conditions. The present Maquoketa Shale acritarch palynoflora shows greatest similarity to those of the Sylvan Shale (Ashgill; Richmondian) of Oklahoma and the Maquoketa Shale (Caradoc and Ashgill) of Kansas. Whereas there are some cosmopolitan acritarch species present in the Maquoketa Shale, its palynoflora shows no pronounced similarity with age-equivalent acritarch suites from outside of North America.

The oldest known microsaur is preserved in a nodule from the Kinkaid Formation (Mississippian; Elvirian) collected near Goreville, Illinois. At least eight individuals are represented: three by partial skulls plus vertebral column segments with associated limb elements, and five by postcrania only. Skulls are crushed, incomplete, and exposed mainly in palatal view. Palatal bones are denticulate and the palatine has in addition a single large tooth. The basipterygoid process is laterally directed and the basipterygoid joint is open. The atlas carries large articulating facets for proatlantes, a pair of which are identifiable in one specimen. These features have not been found previously in a microsaur. All vertebral segments are dominated by a biconcave pleurocentrum; sutures between the pleurocentrum and neural arch are visible in presacral vertebrae. Distinctive microsaurian intercentra occur between all presacral pleurocentra. Their presence reinforces the hypothesis that microsaur intercentra are homologous with those of other early tetrapods. Caudal vertebrae retain separate haemal arches and some have ribs.

Observed microsaur synapomorphies include: atlas with large median odontoid; atlas with concave lateral facets for occipital condyle; paired occipital condyles that are broad and concave; and thin, straplike intercentra. No observed features support a sister-group relationship with any other microsaur species, or placement within any higher level microsaur group. Because significant portions of the skeleton are missing or inaccessible, the Goreville microsaur is not formally named. A standardized, hierarchical format for skeletal characters is introduced that facilitates data sharing and comparison and fosters rapid archiving and retrieval.

Family Orthothecidae Sysoev, 1958 is herein emended to encompass only hyoliths that possess a very shallow longitudinal ventral concavity and a tightly rounded dorsum, resulting in a near-triangular to only slightly kidney-shaped cross section. Orthotheca Novak, 1886 is restricted to orthothecids that possess longitudinal ornamentation on the dorsum, with Cryptocaris suavis Barrande, 1872 now recognized as the type species of that genus. Based on the revised generic concept, orthothecids from the Lower Devonian (Emsian) Shriver Chert of northeastern Pennsylvania are here included within the genus as Orthotheca shriveri n. sp., making this the first occurrence of the genus in North America. The Orthothecida were a group of sessile, benthic hyoliths that ranged from Early Cambrian to Early Devonian. Their life habit appeared to have included filter-feeding. Their ability to retract the operculum into the shell when closed probably aided in preventing sediment influx, and the ventral furrow may have been an adaptation to differing degrees of firmness of the underlying substrate. Despite faunal linkages between the Devonian paleocontinents, the majority of orthothecid genera seem to be largely restricted to their type areas, although Orthotheca documented herein has eroded slightly their endemic character.

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.

Fossil evidence of barnacle encrustation of vertebrate bones is reported from the middle Pleistocene Port Orford Formation of southern coastal Oregon. This material includes two associated thoracic vertebrae and a femur referable to the extinct sea lion Proterozetes ulysses that are encrusted by 1400+ individual barnacles (cf. Hesperibalanus hesperius), and a scapula of Zalophus californianus with barnacle attachment scars. In areas, the encrusting barnacles exhibit a roughly bimodal size range, and small barnacles are observed directly encrusting other larger individuals. The size, probable age, and lifespan of extant Hesperibalanus hesperius indicates a minimum period of four to seven months of seafloor exposure between decomposition and burial, although this estimate must be longer because at least two colonization events are represented. Barnacle attachment traces are identified as Anellusichnus circularis. The wide distribution of barnacles on some of these bones suggests these were regularly overturned by bottom currents, which would prevent barnacles from being smothered by prolonged contact with the sediment. Detailed study of barnacle-induced trace fossils on these specimens suggests that episkeletozoans and their traces can be useful sources of data regarding the biostratinomic history of vertebrate fossils.

Hystricurus millardensis Hintze, 1953 has been recorded widely in Laurentia. Revision on the basis of abundant new silicified topotype material indicates that most of these records are of morphologically distinct, though related, taxa and that a plexus of related species is involved. The new genus Millardicurus, with H. millardensis as type, is proposed for this clade, which also includes two well-documented new species, M. housensis and M. paramillardensis, from the House Formation of western Utah, several named species from Greenland, and several unnamed new species from various parts of Laurentia that have in the past been referred to M. millardensis. Millardicurus is not apparently closely related to younger Skullrockian-Stairsian hystricurids from Laurentia, but may be related to poorly known coeval Siberian Platform species classified in the genus Nyaya Rozova, 1963. Landmark-based geometric morphometric methods comprising principal component analysis of partial warp scores and Goodall's F test of pairwise means indicate significant shape differences among cranidia, librigenae, and pygidia of the House Formation species of Millardicurus.

Volutes are widely distributed in the Cenozoic record of Patagonia and Tierra del Fuego, where they are represented by the South American endemic genera Adelomelon Dall, 1906, Pachycymbiola Ihering, 1907, Odontocymbiola Clench and Turner, 1964, and Miomelon Dall, 1907. These taxa have been restricted to the southwestern Atlantic and southeastern Pacific Oceans from Tertiary times to the Recent, and since their earliest record in the ?Middle Eocene–Late Oligocene–earliest Miocene they have evolved adaptations to variations in water depth and temperature. These ecological adaptations were less marked for Adelomelon and Pachycymbiola, which have achieved a similar geographical pattern since the Tertiary, but they were strongly modified in Miomelon. In the Atlantic, Miomelon migrated southwards from the shallow and warm-temperate waters that it typically inhabited during the Tertiary, to deeper, colder waters of the Recent Magellanic Province and Subantarctic region, where it is restricted at present. A detailed discussion of the validity of Tertiary genus Proscaphella Ihering, 1907 herein concludes it to be a synonym of Miomelon Dall, 1907. Seven species are redescribed and illustrated: Adelomelon pilsbryi (Ihering), A. cannada (Ihering), A. (Pachycymbiola) ameghinoi Ihering, ?Pachycymbiola feruglioi (Doello Jurado), Miomelon gracilior (Ihering), M. dorbignyana (Philippi), and M. petersoni (Ortmann); and four new ones are described: Miomelon castilloensis, Pachycymbiola chenquensis, P. camachoi, and P. arriolensis.

Food gathering of some adult Upper Ordovician crinoids was modeled by means of filtration theory. The arm-branching patterns of the 13 species examined range from nonpinnulate isotomous arms to uniserial and biserial arms with numerous pinnules. Most taxa are roughly equivalent with respect to ambient current velocities and the nutrient contents needed from seawater. Two species with extensively branched arms have markedly higher nutritional requirements at any one ambient current velocity. The results are somewhat correlated with environment in the form of differential current velocities, water flow patterns, and food abundance and composition. The data are generally compatible with filtration theory and the environmental distributions of many Ordovician and other Paleozoic crinoids, and they reveal that Upper Ordovician crinoids had at least partially developed the ecological patterns seen in later Paleozoic crinoids. Various morphological, physiological, and behavioral changes can be employed by crinoids to alter their nutritional balance. The size distributions of food particles that are caught by the crinoids are modeled. These food particle distributions for the Ordovician fossils resemble those of modern crinoids. Relative to the population of food items, the distributions of particles that are trapped are shifted towards larger items because the crinoid filtration nets are more efficient at catching larger particles. Crinoids with relatively open filtration nets and large food-catching tube feet are generalized and feed on a wide range of food particles of a relatively large mean size. The more specialized taxa with extensively branched arms bearing small and closely packed food-catching tube feet are restricted to a more narrow range of smaller food particles.

The atlas-axis complex in the Early Permian diadectomorph Diadectes is shown to be similar to those of a variety of primitive amniotes. Diadectes does not possess elements in addition to the standard complement seen in advanced batrachosaurs and primitive amniotes as previously thought. Characteristics of the complex include: paired, well-developed proatlases and atlantal neural arches, lack of atlantal neural spines, an extremely robust atlantal intercentrum, fusion of the atlantal pleurocentrum and axial intercentrum, a large anterior projection of the axial intercentrum, exclusion of the atlantal pleurocentrum from ventral exposure, fusion of axial neural arch and pleurocentrum, and a robustly developed axial neural spine. An analysis of the transformations of the atlas-axis complex in advanced anthracosaurs and primitive amniotes indicates that many of the characteristics of the complex previously thought to be definitive of amniotes or reptiles appear to be conditions common to Diadectes plus Amniota.

During the Cenozoic, the New World tropics supported a rich biodiversity of mammals. However, because of the dense vegetative ground cover, today relatively little is known about extinct mammals from this region (MacFadden, 2006a). in an exception to this generalization, fossil vertebrates have been collected since the second half of the twentieth century from Neogene exposures along the Panama Canal. Whitmore and Stewart (1965) briefly reported on the extinct land mammals collected from the Miocene Cucaracha Formation that crops out in the Gaillard Cut along the southern reaches of the Canal. MacFadden (2006b) formally described this assemblage, referred to as the Gaillard Cut Local Fauna (L.F., e.g., Tedford et al., 2004), which consists of at least 10 species of carnivores, artiodactyls (also see recent addition of peccary in Kirby et al., 2008), perissodactyls, and as described by Slaughter (1981), rodents. Prior to the current report, the horses (Family Equidae) from the Gaillard Cut L.F. consisted of only four fragmentary specimens including: two isolated teeth, i.e., one each of Archaeohippus sp. Gidley, 1906 and Anchitherium clarencei Simpson, 1932; a heavily worn partial dentition with p2-p4 of A. clarenci; and a partial calcaneum of Archaeohippus. Although meager, these fossils appear to represent two distinct taxa of three-toed horses otherwise know from the middle Miocene of North America, i.e., the dwarf-horse Archaeohippus sp. and the larger Anchitherium clarencei.