Paleontological studies of organisms with accretionary skeletons should take full account of the implications of accretionary growth. These implications are discussed in this paper with examples from the Brachiopoda.

Descriptions of morphology should recognize the ‘dynamic’ character of preserved structures as embodying a sequence of previous growth stages; ‘static’ descriptions can result in misleading morphological characters and spurious taxonomic distinctions. Analysis of ontogeny in dynamic terms, and particularly the topological comparison of structures of varied form, can help distinguish true from false homologies, and hence evaluate the probability of inferred phyletic pathways. Such analyses can also be used to infer the morphogenetic ‘rules’ that governed the development of particular structures and, hence, to locate major phyletic innovations and discontinuities in structure.

Four distinct classes of functional interpretation are applicable to accretionary structures. Functional analysis of structures developing through ontogeny can help to discriminate between analogical and homological resemblances and to identify functional changes during ontogeny. Likewise, functional interpretation of postulated transformations of structure can be used to evaluate the phylogenies suggested; interpretation of structures that are functionally dependent on absolute size can also help to identify major adaptive innovations and discontinuities.

The ontogenies of Prorensselaeria and Nanothyris, described here for the first time, suggest that Cloud's Dielasmatidae are closely affiliated phylogenetically with Cloud's Centronellidae. This is based on the fact that the type species of Nanothyris goes through an initial mutationellinid (Cloud's Dielasmatidae) growth stage before reaching its adult rensselaerinid (Centronellidae) growth stage. The ontogeny of Prorensselaeria requires that it be transferred from the Globithyrinae (Rhipidothyrididae) to the Mutationellinae (Meganteridae [=Cloud's Dielasmatidae = Stehli's Mutationellidae]). Further consideration of their ontogenies permits the transfer of Meganteris, Meganterella, and Reeftonella to the Meganterinae of the Meganteridae. It is recommended, because of the placement of Meganteris in the Meganterinae, that the term Meganteridae replace Mutationellidae, and Mutationellinae be restricted to costate Meganteridae. The subfamily Adreninae of the Meganteridae (=Stehli's Mutationellidae) is proposed to include Adrenia, Cydimia, Micidus, Sturtella, Barbarothyris, and Lingshanella.

The information developed here permits one to conclude that there are two kinds of families: 1) those generated by directional selection, involving major adaptive radiations, the type generated by quantum evolution in Simpson's sense; and 2) those generated by minor developmental changes, that do not involve major adaptive radiations, although they do result in morphological and biogeographical differences great enough to warrant the erection of families.

Jugiaster n. gen. is based on the Upper Ordovician asteroid (Echinodermata) Petraster speciosus; in addition, a second Upper Ordovician occurrence, Phyrtosaster casteri, new gen. and sp., is described. Both species exhibit mouth frame characters suggestive of those long considered typical of early ophiuroids, thereby demonstrating the adaptive versatility and complexity of asterozoan diversification. Jugiaster specimens also exhibit delicate ambulacral column articulation. The new fossils indicate the need for much further study before early asterozoan history will be well understood.

Madrynomya bruneti n. gen. and sp. is an undescribed bivalve collected from the late Miocene Puerto Madryn Formation in northern Patagonia. The specimens were collected together with other generally well-preserved mollusks from a parauthochtonous assemblage within a fine-grained sandstone. Based on their unique shell morphology, the specimens are placed in the Modiomorphoidea, a group of bivalves known only from the Paleozoic and Mesozoic. This conclusion is based on comparisons with other bivalve taxa such as Mytiloida, Dreissenidae, Modiomorphidae, Hippopodidae, and Anomalodesmata, which they resemble in different morphological features. However, careful inspection of key characters suggests that none of them are closely allied to this new genus, and placement in the Modiomorphidae is only tentative until more material is found and further characters, such as shell microstructure, can be properly analyzed. Likewise, an accurate reconstruction of this bivalve's life habit is presently impossible to determine with the two available specimens, but an endobyssate mode is probable, as has been inferred for Myoconcha.

Conodonts from the upper Burgen, Tyner, and Fite Formations (Middle Ordovician) of eastern Oklahoma include two new species, Phragmodus harrisi and Plectodina tynerensis. The conodont fauna indicates that the upper Burgen through middle Tyner is Whiterockian (pre- to earliest Chazyan) and that the upper Tyner–Fite is probably Kirkfieldian in age.

The Whiterockian Burgen–Tyner preserves a regressive succession of shoreface, lagoonal, and intertidal deposits. That change is reflected by the conodont succession, which shows replacement of a fauna dominated by species of Neomultioistodus, Scandodus?, and Paraprioniodus by one dominated by species of Phragmodus, Plectodina, and Erismodus.

Carbonate deposits of the Kirkfieldian(?) upper Tyner and Fite Formations follow a major hiatus and reflect shallow, subtidal to intertidal conditions. The conodont fauna is composed of species of Aphelognathus, Plectodina, Curtognathus, Erismodus, and Oulodus, among others.

The Pleistocene fossil sloth Australonyx aquae De Iuliis, Cartelle, and Pujos, 2009 (Mammalia, Xenarthra, Megalonychidae) was described from the intertropical region of Brazil. However, its mandible was not known and only cursory descriptions of the ear ossicles were included. The mandible was subsequently recognized among the remains originally collected from the type locality, and belongs to the holotype individual. As a particularly important skeletal element for specific recognition, it requires description to complement our understanding of this species. The ossicles, usually poorly represented in the fossil record, require further description to allow differentiation from those of other sloths. Comparisons of the mandible and ossicles are conducted with homologous elements of the contemporaneous and sympatric Ahytherium aureum Cartelle, De Iuliis, and Pujos, 2008, the only other megalonychid sloth known from intertropical Brazil, and reinforce the distinction between these two species detailed in their initial descriptions. Comparisons with other sloths (e.g., Acratocnus, Megalonyx, Neocnus) also reveal differences with Au. aquae in such features as form and size of the caniniform tooth, angular process, and mandibular condyle. Differences among the malleus and incus of Au. aquae and several species of other sloth clades reveal clade level distinctions among Megatheriidae, Nothrotheriidae, and Megalonychidae. A well-preserved skull from the Brazilian state of Rondônia is noted as probably belonging to Au. aquae. This skull cannot be assigned formally to this species because it is not deposited in a recognized institution, but it does extend considerably the known range of the species.

Analysis of previously unstudied shell characters reveals the existence of three new genera of Cenozoic muricid neogastropods. These are the new genera Muregina (type species: Murex lugubris Broderip, 1833; ?early Miocene, Pliocene to Recent, eastern tropical Pacific); Kestocenebra (type species: Murex curvicosta Grateloup, 1840; early to late Miocene, Europe); and Edithais (type species: Concholepas drezi Vokes, 1972; early to late Miocene, circumtropical).

A review of muricids with a labral tooth (a ventrally directed projection on the outer lip) shows that this structure forms in several distinct ways. It may form at the end of an external groove (as in Muregina) or cord (as in Kestocenebra), grow continuously or discontinuously, and lie at positions ranging from the upper end of the siphonal canal to just below the middle of the outer lip. The labral tooth evidently evolved independently several times, often quite recently in genera such as Muregina, in which older representatives lack a labral tooth.

McRoberts (1992, figs. 4.13, 4.14, 6.8) illustrated the shell microstructure of late Triassic Gryphaea (Gryphaea) arcuataeformis Kiparisova, 1936, and Gryphaea (Gryphaea) nevadensis McRoberts, 1992. McRoberts (1992, p. 33) described the left valve of G. arcuataeformis as showing “neomorphosed calcite with multiple laminae of ?prismatic structure perpendicular to [the] outer shell surface ….” He described the left valve of G. nevadensis as consisting of two distinct layers of neomorphosed calcite:“…an outer layer with ?prismatic structure occasionally with bands of dark material (?micritic matrix), and a much thinner inner layer with ?cross-foliated structure ….” Subsequent study has shown these microstructural diagnoses to be inaccurate. They are revised as follows.

The bryozoan fauna from the South American Cenozoic is poorly known. The study of new material collected in the Monte León Formation (early Miocene), gave us the opportunity to describe four new species: Valdemunitella canui n. sp., Foveolaria praecursor n. sp., Neothoa reptans n. sp., and Calyptotheca santacruzana n. sp. Two of them (V. canui and C. santacruzana) were first recorded by F. Canu and interpreted as recent species from the Australian bryozoan fauna, but are herein described as new species. The stratigraphic range of Otionella parvula (Canu, 1904) is extended to the early Miocene. The present study emphasizes the close relationships between the South American Neogene bryozoan faunas and those of other Gondwanan sub-continents such as New Zealand and Australia.

The first Laurentian records of Pacificurus Ramsköld, 1986 are provided by Pacificus chilorhodus n. sp. (latest Llandovery?–early Wenlock, Mackenzie Mountains, Canada) and Pacificurus sp. A (early Ludlow, northern Maine). These closely related species represent an early divergence (minimally late Llandovery) from Australian/Asian congenerics.

Records of abnormal fossil arthropods present important insight into how extinct forms responded to traumatic damage and developmental complications. Trilobites, bearing biomineralized dorsal exoskeletons, have arguably the most well-documented record of abnormalities spanning the Cambrian through the end-Permian. As such, new records of malformed, often injured, trilobites are occasionally identified. To further expand the documentation of abnormal specimens, we describe malformed specimens of Lyriaspis sigillum Whitehouse, 1939, Zacanthoides sp. indet., Asaphiscus wheeleri Meek, 1873, Elrathia kingii (Meek, 1870), and Ogygiocarella debuchii (Brongniart, 1822) from lower Paleozoic deposits. In considering these forms, we propose that they illustrate examples of injuries, and that the majority of these injuries reflect failed predation. We also considered the origin of injuries impacting singular segments, suggesting that these could reflect predation, self-induced damage, or intraspecific interactions during soft-shelled stages. Continued examination of lower Paleozoic trilobite injuries will further the understanding of how trilobites functioned as prey and elucidate how disparate trilobite groups recovered from failed attacks.

The Zittel wing of Rhamphorhynchus muensteri is reinterpreted as preserving negative impressions of closely spaced broad flat actinofibrils that were replaced by calcite but were prepared away by the specimen’s finder. The Marsh specimen preserves positive impressions of the dorsal and ventral surfaces of the wing, which show that the skin was smooth with fine wrinkles and that actinofibrils were not on the wing surface. Based on comparisons of those specimens, the dactylopatagium consisted of dorsal and ventral skins of epidermis and dermis surrounding a common hypodermis core, and keratinous actinofibrils developed in place within the dorsal epidermis adjacent to a layer of linear collagen fibers in the dorsal dermis. The actinofibrils and linear collagen fibers together formed the main functional structure of the dactylopatagium. That structure made the dactylopatagium somewhat stiff and essentially inextensible so that it folded up along discrete fold lines that probably were genetically determined. A pneumatic retrophalangeal wedge behind the antebrachium through at least wing phalanx 3 streamlined the transition between the thick wing spar and thin patagium.

Six species belonging to the families Proporidae and Plasmoporidae occur in the Lower and Upper Silurian rocks of the Limestone Point and La Vieille Formations of northern New Brunswick and of the Anse à Pierre-Loiselle, La Vieille, and Gascons Formations of the Gaspé Peninsula of Québec. The three species of Propora are widely distributed but show varying faunal affinities, while both species of Plasmopora, Plasmopora logani and Plasmopora corrugata, are new and are almost endemic. Revised concepts of Propora and Plasmopora are proposed. The holotype specimen for the type species of Camptolithus was examined and confirms the genus as distinct from Propora, rather than a synonym as has been previously suggested.

The facies distribution of these corals is variable. In general, the proporids, which mostly occur in facies indicating shallow carbonate banks and patch reefs, are more restricted in distribution than the plasmoporids, which occur in these facies and also in others representing a variety of open-shelf environments.

In neoceratopsian dinosaurs, the centra, neural arches, and neural spines of several anteriormost cervical vertebrae are fused together to form a structure called the cervical bar (Langston, 1975) or syncervical (Ostrom and Wellnhofer, 1986). This structure characterizes all neoceratopsians (Dodson and Currie, 1990; Dodson et al., 2004; You and Dodson, 2004) for which the anterior cervicals are known, but it remains controversial how many vertebrae are fused together to produce this structure, namely, whether it consists of the first three (atlas through the third cervical) or four (atlas through the fourth cervical) elements. Analyses of ceratopsian interrelationships have employed from two (Sereno, 1984; Chinnery, 2004) to five (Xu et al., 2002) characters related to the cervical bar; accordingly, sorting out the exact identities of the elements contributing to this structure may have implications for our understanding of support, branch lengths, and rates in ceratopsian evolution.

Cyclocystoids (range: Ordovician–Devonian), particularly of Devonian age, are extremely rare fossils and stratigraphic ranges of most taxa are little known. For this reason, the discovery of a single fragmentary specimen referable to Sievertsia (Smith and Paul, 1982) from the Traverse Formation (Middle Devonian) in Cass County, northern Indiana, deserves mention. Furthermore, the precise stratigraphic position of the cyclocystoid occurrence is documented by a combination of significant conodont and brachiopod faunas. The specimen was collected in situ on a weathered surface from a position approximately 1.2 m above the base of the type section of the Miami Bend Lithofacies (Cooper and Phelan, 1966, p. 6, U.S. National Museum Locality 391a; Orr, 1969, p. 338, Locality 5) exposed at the top of the west wall of the old France Stone Company quarry (inactive) on the north side of U.S. Highway 24, 3.2 km east of Logansport, SW¼, NE¼, sec. 27, T27N, R2E, Cass County, Indiana (Logansport 7½′ quadrangle).

Two amphibian taxa are reported for the first time from the lower to middle Miocene shallow-marine Calvert Formation. These are Batrachosauroides aff. B. dissimulans (a large proteoid salamander) and cf. Notophthalmus robustus (a small newt). Four kinds of identifiable nonmarine turtles were reported previously from this formation. These are Bairdemys miocenica (a pleurodire), Kinosternon sp. (a musk turtle), Hesperotestudo ducateli and Hesperotestudo wilsoni (tortoises). Four additional taxa reported here are Chrysemys isoni n. sp. (a painted turtle), Trachemys sp. (a pond turtle), Floridemys hurdi n. sp. (a small tortoise), and Apalone lima (a softshell turtle). Most of these taxa are known from elsewhere in the Atlantic and Gulf Coastal Plains from New Jersey to Texas. The regional widespread occurrence of many of these taxa indicates that they represent a modestly diverse community of amphibians, fresh water turtles, and land turtles that were endemic to the Atlantic and Gulf coastal regions of the United States during the late early and early middle Miocene. Their pattern of distribution is similar to that of eastern American land mammals during this time interval, indicating that the Atlantic and Gulf coastal plains of the southeastern United States then lay within a single climatic zone that constituted a distinctive and long-lived faunal province throughout the early and middle Miocene (Hemingfordian through Barstovian land mammal ages).

Microforaminiferal linings assigned to 10 known genera have been recovered from Early Devonian (Lochkovian to Late Emsian) limestones from Victoria, New South Wales, and Queensland. These organic linings have been identified by comparison with normal-sized agglutinated foraminiferan genera known to occur in the associated sediments. Microforaminiferal linings with smooth walls and reticulate sculptured walls were present and the possible implications of these (diagenetic, relict structure, naked homeomorphs, or processing artifact) are discussed. Evidence is presented that Ordovicina may have a bilamellar organic wall lining.

The genus Baffinicythere is a northern high-latitude marine ostracode, which includes four species: B. howei Hazel, B. ishizakii new species, B. reticulata new species, B. robusticostata new species. The first species occurs only in late Pliocene to Recent sediments of the Arctic and northern Atlantic Oceans. The remaining three species are abundant in the Plio–Pleistocene formations of northern Japan, which yield cold-water molluscan faunas. Detailed morphological analyses and paleogeographic distribution of the three new species indicates that: 1) B. reticulata has some primitive characters relative to the other two species; 2) B. ishizakii and B. robusticostata seem to have had different strategies as regards rate of ontogenetic size increase; 3) the left valve outlines can be resolved into two components, ontogenetic shape changes and species-specific distinctions among the species; and 4) B. robusticostata invaded areas inhabited by B. reticulata and may have excluded it during the late Pleistocene. The Atlantic species B. howei has not been recorded from northern Japan. Comparisons of B. reticulata and B. howei, based on their pore distribution and reticulate sculptures, suggest that B. reticulata could have migrated to the Arctic Province after the Bering land barrier had been breached and then evolved rapidly into B. howei.

Abundant and diverse dinosaur footprints have been discovered recently on bedding surfaces of the Lower Cretaceous Patuxent Formation of Maryland and Virginia. Found along with those ichnofossils is a fossil preserved partially as natural casts and partially as natural molds of a baby nodosaurid ankylosaur so small as to justify interpreting it as a hatchling. Despite the rather unusual type of preservation, the find is properly termed a body fossil and not an ichnite, per se, because it records not the action of an organism, but the body form and bone structure (including partial articulation) of a dinosaur. We here name it Propanoplosaurus marylandicus and provide a description of its diagnostic characteristics. Although actual skeletal remains referable to P. marylandicus have not been found in the Patuxent Formation, other nodosaurids recognized from skeletal remains are known from both the Lower and Upper Cretaceous strata of the Western Interior of North America and Europe. P. marylandicus represents the only diagnostic nodosaurid from the Early Cretaceous of the eastern U.S.A., provides information on growth patterns among nodosaurids, and is the first direct evidence of a dinosaur hatchling and, deductively, nesting, on the entire eastern seaboard.

A new upper Bajocian ammonite assemblage containing the morphoceratids Dimorphinites dimorphus (d'Orbigny) and Vigoriceras defrancei (d'Orbigny) is reported from the circum-Pacific area. These ammonites were found at the top of the Torcazas Formation, in the Quebrada San Pedro area, Precordillera of northern Chile. Taphonomic, systematic, and paleobiogeographic data confirm these dimorphs were part of indigenous populations within the Tarapaca Basin, belonging to the same demic biospecies: Dimorphinites defrancei (d'Orbigny). The West Tethyan and East-Pacific distribution of D. defrancei corroborates the availability of the migratory seaway, the so-called Hispanic Corridor, between the western Tethys and the eastern Pacific Ocean during the upper Bajocian Parkinsoni Zone. The discovery of this upper Bajocian Dimorphinites assemblage provides a new biochronostratigraphic horizon in the Tarapaca Basin and an interoceanic correlation point for the latest Bajocian.