Litopterna is represented in the Pleistocene of the Brazilian Intertropical Region by a monospecific genus of Macraucheniidae, Xenorhinotherium. Although most of the knowledge about this family is derived from the dentition, some dental features still remain unknown. This study describes the eruption sequence of permanent dentition and classifies the hypsodonty status of X. bahiense. The specimens studied are from Toca dos Ossos, a limestone cave located in Bahia State. We perform qualitative macroscopic analysis to describe the eruption dental sequence. Additionally, we perform quantitative analysis to determine the hypsodonty index. The dental eruption sequence of the juvenile specimen is M1, M2, I1, I2, M3, I3, P1, P2, P3, and P4. In addition, the analysis of tooth wear in adult specimens provides similar results. The hypsodonty index assigns a mesodont tooth crown for X. bahiense. The dental eruption sequence is most similar to a rapid-growth extant mammal. Moreover, our results do not support afrotherian-like delayed dental eruption to Litopterna. The hypsodonty index can be related to data on vegetation of the Brazilian Intertropical Region and the shape of the premaxilla of X. bahiense, both of which suggest a browsing diet for this macraucheniid.

The late Jurassic Paulchoffatiinae, one of two named subfamilies of the family Paulchoffatiidae (suborder Plagiaulacoidea), are generally recognized as the most primitive known, undoubted multituberculates (e.g., Hahn, 1969; Clemens and Kielan-Jaworowska, 1979; Hahn and Hahn, 1983; Hahn et al., 1989). Despite the primitive morphology of members of this subfamily (Paulchoffatia and Pseudobolodon), three features have been posited as autapomorphic for the subfamily (or family), and thus to preclude it from the ancestry of later multituberculates: 1) the distribution of cusps on M2 (Hahn, 1969, 1971); 2) the complex structure of I3 (Hahn, 1969, 1971); and 3) the position of M2 relative to M1 (Van Valen, 1976; Clemens and Kielan-Jaworowska, 1979; Hahn, 1987). Van Valen (1976) argued that the first two features are not unequivocally autapomorphic for paulchoffatiines and that they could, and indeed should, be considered primitive for the order. Hahn (1977) responded to Van Valen's assessment but Clemens and Kielan-Jaworowska (1979, p. 138) opined that “neither argument is particularly compelling” in light of the poor early record of multituberculates and the consequent lack of knowledge concerning morphological variability.

By the end of the Cretaceous, the Clavagellidae (Mollusca: Pelecypoda) maintained a distribution that was marginal to the core-Tethys, occurring in both North America and the Old World. Traditional paleozoogeographic interpretation contends that the clavagellids then went extinct in the New World because no Cenozoic fossil or living clavagellids have been documented from the Western Hemisphere. This report describes the occurrence of Eocene clavagellids from the Ocala Group of peninsular Florida. The presence of these pelecypods in Upper Eocene strata is consistent with the large Tethyan faunal component already known from this unit and requires a reassessment of Tertiary zoogeographic patterns for the clavagellids.

Two new well-preserved cornute stylophorans from the Upper Cambrian Whipple Cave Formation represent a new genus and species assigned here to Cardiocystella prolixora. These nearly complete specimens contain morphological information not available from other cornute specimens previously collected from this formation. Both specimens are preserved with superior faces exposed. One specimen contains a nearly complete theca but a somewhat disrupted aulacophore, whereas the other theca has been partially damaged by burrows but has a nearly complete but moderately eroded aulacophore. Cardiocystella prolixora exhibits wide marginals, abundant supracentral platelets, and an aulacophore with cover plates. Supracentral platelets cover much of the interior regions of the theca, which lacks a visible zygal bar in both specimens. In holotype 1791TX13, a bulge in the superior face of the theca likely shows the zygal bar position. The wide marginals of these new specimens resemble those of a specimen previously described from a partial theca and aulacophore assigned to Archaeocothurnus species indeterminate (Sumrall et al., 1997); however, the specimens described here are heart-shaped rather than boot-shaped. The placement of this specimen in a new genus and species is based on its unique marginal shape and arrangement.

Phylloid (leaf-shaped) fossil algae are common constituents in sedimentary rocks of Late Pennsylvanian through Early Permian age in the Midcontinent, U.S.A., commonly producing porous algal-rich bioherms that may be prolific petroleum reservoir rocks. During the course of re-evaluating the paleontological character of these fossil algae in Kansas, remarkably well-preserved codiacean algae were found in an oncolitic nodule in the Wakarusa Limestone Member of the Bern Limestone (Virgilian) in Lyon County, Kansas. Although this is the locality and stratigraphic bed from which the genotype Anchicodium funile Johnson, 1946, was collected, the new alga is not of that genus, but occurs with specimens of Anchicodium.

Describing the chemical ontogeny of 36 specimens of Nautilus allowed the identification, as well as the determination of the relative effects, of the controls on Mg and Sr concentration in skeletal aragonite. The previously documented trend that aragonite contains higher concentrations of Sr than Mg persists within skeletal structures of Nautilus. This relationship suggests that neither physiological nor environmental controls overwhelm the mineralogical control. Significant differences in Mg and Sr concentrations of nacreous shell, prismatic shell, and septal nacre suggest that these structures may form from extracellular fluids with differing elemental concentrations. Many specimens exhibit greater variability of Mg and Sr concentrations in juvenile portions of the skeleton than in more mature portions. This suggests that either the physiochemical system matures during ontogeny and achieves increasing control over skeletal chemistry or the organism adjusts to the new conditions and behavioral maturation stabilizes elemental concentrations by reducing stress. The decreased growth rate that Nautilus experiences as it approaches maturity does not effect Mg or Sr concentrations. Differences in combined Mg and Sr concentrations among species of Nautilus indicate that extracellular fluids that produce each skeletal structure are chemically distinct, with the exception of the fluids that produced septal aragnite of N. belauensis and N. scrobiculatus, and exemplify phyletic control of trace element concentration at the species level. Although significant chemical separation exists among species of Nautilus, sufficient variation and overlap persists in elemental concentrations to make a classification based solely on these two elements ineffective. Significant chemical differences between two sympatric species of Nautilus demonstrate that physiological systems, and not environmental variables, primarily control elemental concentrations in skeletal aragonite.

In four genera of schizotheriine Chalicotheriidae—Moropus, Tylocephalonyx, Phyllotillon, and Ancylotherium–proximal and middle phalanges of digit II of the manus fuse to form a duplex bone. Fusion of proximal and middle phalanges of digit II of the pes also occurs in many species of these genera. Radiographic and sagittal-sectional study of the fused duplex phalanges of Moropus elatus and Tylocephalonyx skinneri shows that the joint between the two bones formed fully prior to fusion but had little movement. Fusion proceeded by external enthesial interactions at the insertion of the ligament capsule and by disruption of cortical bone with trabecular bridging along the internal part of the original articular surface. Cortical disruption is more rapid on the middle than on the proximal phalangeal component of the duplex. In M. elatus, the degrees of external and internal fusion roughly correspond, and a ventral surficial groove sometimes traces the former facet, whereas in T. skinneri external fusion is much more developed than internal fusion. Phalangeal fusion seems to have strengthened the digit against strong forces applied along the medial (radial or tibial) side of the foot.

Two new species, Mojavemys galushai and Phelosaccomys neomexicanus, are described from the Barstovian of New Mexico. Both of these species are assigned to a new subfamily, the Mojavemyinae. It is uncertain as to whether this new subfamily should be referred to the Heteromyidae or Geomyidae.

Both Mojavemys an Phelosaccomys retain some heteromyid characteristics while developing advanced traits of geomyids. It is possible that these genera represent transitional forms between a heteromyid ancestor and advanced geomyines, thus deriving the Geomyidae directly from the Heteromyidae sometime in the middle Tertiary. It is also possible that the Mojavemyinae are a subfamily of heteromyids only convergent with geomyids. A third possiblity is that the mojavemyines are among a group of middle Tertiary geomyoids from which both Recent heteromyids and geomyids were derived.

The generic name Terebellina was proposed by E. O. Ulrich for large (> 100 mm long, several millimeters wide), siliceous, tubular fossils from Cretaceous rocks of southern Alaska. Originally interpreted as annelid tubes, these unusual agglutinated fossils are locally abundant in Triassic to Neogene flysch and other basinal deposits of the Pacific borderlands. Other generic names employed for the same fossils include Torlessia (used in New Zealand) and Yokoia (in Japan). Although most authors have regarded the tubes as body fossils of worms, some workers have speculated recently that Pacific Terebellina are really large bathysiphonid foraminiferids. At the same time, the name has been co-opted by trace fossil workers for thick-walled, grain-lined burrows usually occurring in outer-shelf to slope facies.

Based on comparisons with modern and fossil bathysiphonids, including a new species (Bathysiphon harperi) from the Cretaceous of southwestern Oregon, the body fossils called Terebellina are here reinterpreted as large species of Bathysiphon, and the name Terebellina is therefore a junior synonym of this foraminiferid genus. Except for the compression and recrystallization of tubes, Pacific Terebellina resemble very closely the tests of larger species of modern Bathysiphon. Terebellina should not be salvaged for use as an ichnogenus. Most of the trace fossils identified with this name in the recent literature could be accommodated in other established ichnogenera, primarily Palaeophycus (where grain-lined burrows occur individually and are dominantly horizontal) and Schaubcylindrichnus (where they occur in curved bundles).

During the Eocene, Hahajima Island of the Ogasawara (Bonin) Islands of the Izu-Mariana Arc in the North Pacific was located near the present-day position of western Pacific Micronesia. We identified 17 Eocene ostracode species from the island, of which are new species and likely endemic to this island or to the West Pacific. These new species are systematically described herein and include: Costa matsumarui n. sp., Cytherelloidea ogasawaraensis n. sp., Havanardia ujiiei n. sp., Jugosocythereis nishii n. sp., Neonesidea boninensis n. sp., Schizocythere antiquimicronesiana n. sp., and Uroleberis hahajimaensis n. sp. The Eocene ostracode fauna has a higher rate of endemism than does the modern Micronesian fauna and contains Tethyan genera. These findings contradict a hypothesis that the Pacific fauna had a higher endemism rate after the Paleogene. The findings support another hypothesis that some genera invaded the Pacific from Tethys during the Paleogene. They suggest that West Pacific species did not disperse to the periphery of the Indo-West Pacific region during the Middle–Late Eocene. The “center of origin” hypothesis cannot be applied to Middle–Late Eocene marine ostracode biogeography.

The Late Ordovician (late Katian) Tcherskidium fauna consisted of large- and thick-shelled virgianid pentamerid brachiopods characterized by large and ribbed shells of Tcherskidium and Proconchidium and usually associated with Holorhynchus, Deloprosopus, and Eoconchidium. This unique fauna was widely distributed across several tectonic plates, largely confined to the paleoequatorial and especially the northern paleotropical zones, such as northern Laurentia, accretionary terranes of Alaska, Kolyma, Baltica, Siberia, Kazakh and adjacent terranes, and South China. In Laurentia, the eponymous genus Tcherskidium was predominant in regions north of the paleoequator and, in sharp contrast, was absent south of the paleoequator. In this study, Tcherskidium lonei n. sp. and Proconchidium schleyi n. sp. are described from Alaska and North Greenland, respectively, adding new data on the Tcherskidium fauna of the Late Ordovician Northern Hemisphere. Shell gigantism, together with the sharp paleobiogeographic division, suggests that the Late Ordovician (late Katian) Northern Hemisphere had a prevailing warm-water mass, probably due to the lack of large landmass beyond the northern tropics. This was in sharp contrast to the Southern Hemisphere, which was frequently influenced by cold-water invasions from the ice-bearing Gondwana supercontinent centered on the South Pole.

UUID: http://www.zoobank.org/25d9b772-bd7d-4ad6-bfc6-ba02b1567cf3

Two middle Permian (Capitanian) to Early Triassic (Griesbachian) rugosochonetidae brachiopod genera, Fusichonetes Liao in Zhao et al., 1981 and Tethyochonetes Chen et al., 2000, have been regarded as two distinct taxa and used as such for a wide range of discussions including biostratigraphy, paleoecology, paleobiogeography, and the Permian-Triassic boundary mass extinction. However, the supposed morphological distinctions between the two taxa are subtle at best and appear to represent two end members of a continuum of morphological variations. In this study, we applied a range of quantitative and analytical procedures (bivariate plots, Kolmogorov-Smirnov test, categorical principle component analysis, and cladistic analysis) to a dataset of 15 quantified morphological variables, integrating both key external and internal characters, measured from 141 specimens of all well-known Fusichonetes and Tethyochonetes in order to test whether or not these two genera could be distinguished in view of the chosen characters. The results indicate that these two genera are morphologically indistinguishable and that the species classification previously applied to these two genera appears to represent polyphyletic groupings within the genus Fusichonetes. Consequently, Tethyochonetes is concluded to be a junior synonym of Fusichonetes. The diagnosis and key characteristics of Fusichonetes are clarified and refined based on a new suite of well-preserved specimens from the Permian−Triassic Xinmin section in South China.

Jamaica has the best-known fauna of fossil crinoids of the Antillean islands. Two Cretaceous species have been reexamined on the basis of new material. Lower Cretaceous Apiocrinites sp., previously referred to Austinocrinus n. sp. and first documented from a short pluricolumnal, is now known from brachials and further fragments of column. This is the first millericrinid, and only the second non-isocrinid stalked crinoid, to be identified from the Jamaican and Antillean fossil record. Other ossicles may be derived from the cirri of a comatulid. Applinocrinus cretacea (Bather) is well known from the upper Senonian of England, North America and the West Indies, although Caribbean specimens have not been figured previously. Functional interpretations of the mode of life of Applinocrinus suggest that it was a benthic crinoid, presumably with arms. It lived embedded in the sediment.

Heliolitine corals are closely associated with lithistid sponge-dominated reef mounds in Ludlow carbonate ramp facies on Somerset Island. The corals occur abundantly in argillaceous, fossiliferous wackestone immediately flanking and capping the reef mounds, less commonly in calcilutite mudstone within the reef mounds, and with sharply decreasing abundance in nodular argillaceous wackestone to mudstone away from the reef mounds. Exhaustive field collection, and systematic study that included biometric analysis of collected assemblages, indicates that ten heliolitine species are present, including the new species Heliolites furyi, H. garnieri, and H. greineri, and two unidentified species, Heliolites sp. A, and Podollites? sp. The occurrence of H. subdecipiens Klaamann, 1984, H. tchernyshevi Bondarenko, 1966, H. cf. H. rariformis Tchi, 1976, Stelliporella cf. S. podolica Bondarenko, 1971, and Squameolites anomalus Tchi, 1976 indicates an affinity with Eurasian rather than North American faunas of equivalent age. Many new species have been ascribed to Stelliporella since the mid-1970s; most lack the diagnostic axial structures of the genus and are more appropriately regarded as belonging to Heliolites. Newly defined structures termed septal florets occur commonly in H. garnieri and very rarely in three other species of Heliolites. Effective taxonomic use of septal development requires very careful study because of the degree of intraspecific and intracolony variation in some species.

Oyenaster oblidus, Ocalaster timucum, and Ocalaster seloyi are new genera and species of the family Goniasteridae (Asteroidea) described from the Eocene Ocala Limestone of Florida. Although the fossil record of asteroids is sketchy, goniasterids appear to have been important contributors to marine communities since at least the Middle Jurassic. Similarities between living goniasterids and their fossil precursors indicate that plesiomorphy and convergence have been important in family history, and as a result, taxonomic interpretation is challenging. Even partial fossil goniasterids are rare, forcing systematists to rely heavily on isolated marginal ossicles, although some authors have expressed the need for caution. Building around three new taxa, we suggest that broader approaches can aid systematic interpretation of all crown-group asteroids. We also suggest that the inevitably idiosyncratic interpretations of marginal-based systematics can be partially tested using blind evaluations.

Reconsideration of the nature of zooids in trepostomate Bryozoa defines them as physically connected and asexually replicated colony members that housed systems of organs necessary to perform vital functions for the colonies. Zooids known to contain organs in trepostomes are limited to autozooids, the requisite feeding and sexual units, and polymorphs, including macrozooids and two rare zooids of unknown function. Other colony structures are extrazooidal and remain outside zooidal boundaries throughout colony life. They include the commonly occurring mesopores, exilapores, and styles. This two-part morphologic division of colonies reveals two correlated functions. The essential autozooids dominated the growth patterns and physiology of trepostome colonies; the extrazooidal parts grew concurrently and passively to connect autozooids and to support and strengthen colonies.

A large collection of Silurian Syringoporidae, mainly from the Limestone Point and La Vieille formations of northern New Brunswick, includes one new species and three species previously described from this area. Syringopora lambei n. sp. is distinguished from the superficially similar S. bifurcata Lonsdale by its larger corallites with much broader axial tubes and less frequent corallite contacts. Similar problems which have existed in the past in the distinction of S. compacta Billings and S. reteformis Billings can be resolved, as shown in this study, on the basis of the larger, geniculate and densely-packed corallites of S. reteformis. All four species are defined using more quantitative data than has previously been applied to syringoporid taxonomy. A new lectotype for S. compacta is proposed. Recognition of epibionts on a corallum of S. bifurcata as virtually identical to the “epithecal scales” used to distinguish Syringoalcyon Termier and Termier from Syringopora Goldfuss argues strongly against the continued recognition of the former as a separate genus. Preliminary analysis of syringoporid distributions in relation to stratigraphy and sedimentary associations suggests strong facies and paleoenvironmental control on these distributions. For this reason and because of their long stratigraphic ranges, no well-defined biozonal scheme can be proposed at this time.

A diverse cirriped fauna, including the scalpelloids Cretiscalpellum homseyi n. sp., Arcoscalpellum withersi Collins, Arcoscalpellum bakeri Collins, Virgiscalpellum gabbi heintzi n. subsp., Virgiscalpellum sp., V. cf. V. gabbi apertus Collins, and the brachylepadomorph Brachylepas solida n. sp., occurs in the Upper Cretaceous Mt. Laurel Sand at the Biggs Farm locality on the Chesapeake and Delaware Canal, New Castle County, Delaware. This fauna represents the Maastrichtian Virgiscalpellum Zone originally identified in the Ripley and Prairie Bluff formations of the eastern Gulf Coast.

Cocks and Rong (1989) subdivided the species of the Ordovician brachiopod genus Bimuria into two groups, those with a simple, or not undercut, cardinal process and those with an undercut cardinal process. They placed the second group in a new genus, Cooperea, and grouped Cooperea with Craspedelia in the new subfamily Craspedeliinae of the family Sowerbyellidae. However, the cardinal process of Bimuria ranges from not undercut to undercut within at least two species. Cooperea is therefore placed in synonymy with Bimuria, and Craspedelia is returned to the Bimuriidae.

Cocks and Rong (1989) inferred that, with rare exceptions, the cardinal process of the Plectambonitacea evolved from simple to trifid to undercut. The evidence from Bimuria indicates, however, that the undercut process developed more than once and, in Bimuria, directly from the simple type.

As an adjunct to the above discussion three new species are described: Bimuria gilbertella, Craspedelia intonsa, and Craspedelia sp. 1. Craspedelia is a rarely reported genus documented here for the first time in western North America (northern California). Additional evidence is introduced that the ratio Lmusbv/Lebv decreased from middle to late Ordovician species of Bimuria.

Dimorphosiphon talbotorum n. sp. from the Upper Ordovician Bighorn Dolomite of Wyoming is an ancient representative of the erect skeleton-building green algae. Circumstantial evidence indicates that the original skeletal material was aragonite. If so, D. talbotorum and its Ordovician relatives in eastern North America, Europe, and Kazakhstan are reminders that even morphologically simple aragonite producers could thrive during one of Earth's “calcite sea” intervals.

Unlike previously described Ordovician members of its family, the new species is represented by selectively silicified thalli showing three-dimensional details of internal tubes and a highly variable external form. It differs from a similar taxon, D. rectangulare, in having branched as well as unbranched thalli and in morphology of radial tubes. the new species is the first thoroughly documented record of Dimorphosiphon in western North America. Its stratigraphic position in the Richmondian part of the Bighorn Dolomite correlates with previously reported occurrences of the genus in the Red River Formation of North Dakota and Manitoba.

The Wyoming fossils typically occur as scattered components of wackestone and include both silicified and calcitic individuals. the change in skeletal composition from aragonite to calcite apparently took place before tubes decayed, thus preserving tube morphology. Subsequent silicification varied in degree among specimens, probably reflecting differences in permeability of the secondarily calcitic skeletons.