The Neoproterozoic Ediacara biota at Mistaken Point contains the oldest diverse Ediacaran assemblages and is one of the few known deepwater localities, yet the biota is dominated by endemic forms, nearly all of which remain undescribed. Thectardis avalonensis new genus and species, one of these endemic forms, is a cm-scale triangular fossil with a raised rim and a featureless-to-faintly-segmented central depression. More than 200 specimens occur on two bedding plane surfaces: the 565 Ma E surface and the 575 Ma Pigeon Cove surface, nearly 2,000 m lower in the succession. Morphological and taphonomic data suggest that the organism was an elongate cone that may have lived as a suspension-feeding “mat sticker” with its pointed base inserted into the microbially bound sediment. If true, Thectardis n. gen. would be the tallest-known mat sticker, reaching a maximum height of over 15 cm. Specimens display little ontogenetic change in length:width ratio, suggesting that Thectardis grew uniformly by incremental addition of material to its distal end. Morphological differences between specimens at two well-separated stratigraphic levels may have resulted from evolutionary or ecophenotypic variation.

New and previously described “Sphinctozoan” taxa have been collected from six different localities in northern Spain, all of them dated as Late Carboniferous, from Moskovian to Kasimovian in age. The sphinctozoans in the collection are all assigned to the Demospongiae: a new species of polyglomerate type, Cystothalamia vandegraaffi n. sp., and known species Amblysiphonella barroisi Steinmann, 1882, Amblysiphonella carbonaria (Steinmann, 1882), Discosiphonella mammilosa (King, 1943), Discosiphonella maior (Van de Graaff, 1969), and Sollasia ostiolata Steinmann, 1882. Some of these specimens present interesting paleoecological features, such as the use of a piece of calcareous algae as a hard substrate in a soft muddy bottom and a possible branching pattern determined by photophilic or negative geotaxic growth.

Detailed analysis of certain growth characteristics in Trabeculites maculatus contributes to an understanding of the paleobiology and phylogeny of early tabulate corals. Some coralla of T. maculatus contain peculiar, vertically oriented cylindrical lacunae (open areas) that are lenticular, or in one case circular, in cross section. The nature of these structures and their relation to adjacent corallites suggest that they were formed by the coral in response to soft-bodied biotic associates of unknown taxonomic affinity.

Trabeculites maculatus is an unusual tabulate coral featuring both axial and lateral modes of corallite increase. Axial increase was common, often occurring in association with rejuvenation following injury and less commonly involving normal, undamaged corallites. Lateral increase of normal corallites was typical, but this form of increase could also be involved in the termination of lacunae and occurred in response to a divergent growth pattern around the circular lacuna. Corallite decrease was fairly common, usually taking place adjacent to lenticular lacunae but in some cases involving normal corallites not associated with lacunae. Corallite fusion was uncommon; it could be either temporary or permanent. Conspicuous relocation of corallites and restructuring of corallite arrangement generally involved mass rejuvenation and/or regeneration, usually over a large surface area of the corallum.

The growth features in T. maculatus are fundamentally the same as those in the co-occurring Saffordophyllum newcombae, including types of axial increase unknown in other tabulate corals. The basic paleobiologic similarity of these species supports the interpretation that the genera they represent are closely related phylogenetically. The relationship of these taxa to other tabulates, however, remains unresolved.

A previously unknown Namurian goniatite and brachiopod fauna is described from Southeast Asia. The goniatites provide new insights into their global distribution and the age of the fauna. Two new brachiopod genera, Eileenella Racheboeuf and Plicambocoelia Boucot and Brunton, and five new species are described. The brachiopod fauna is unlike any known previously from Asia.

Based on well-preserved material from the Sinemurian of the western Carpathians, the new subgenus Terquemia (Dentiterquemia) is proposed, which is presently represented only by its type species T. (Dentiterquemia) eudesdeslongchampsi n. sp. Dentiterquemia is separated from Terquemia sensu stricto by a series of denticles along the hinge margin and corresponding, chevronlike ridges on the ligament area. The combination of hinge teeth with a cementing habit is interpreted as a defense strategy inhibiting torsion of the valves as well as manipulation of the animal as a whole. Whereas different kinds of articulating hinge structures evolved independently in several clades of early Mesozoic cementing bivalves, Paleozoic cementing bivalves generally lack such structures. It is proposed that this difference reflects an early Mesozoic proliferation of durophagous predators and therefore points to a beginning of the “Mesozoic marine revolution” soon after the end-Permian mass extinction.

Many bivalves and brachiopods possess multilayered shells. In one such bivalve, Mytiloides ipuanus (Wellman, 1959) (Inoceramidae), the mineralized shell comprises an outer prismatic calcite layer and an inner nacreous aragonite layer. Each of the three shell surfaces—the external, internal, and shell layers' interface—has a distinct sculpture. Pronounced costae on the shell interface are “cryptic” in the sense that, in life, they would have been barely expressed on the internal surface and only expressed as comparatively weak, broad, rounded costae on the external surface. In fossil specimens, depending on the timing of shell dissolution relative to compaction and lithification, any of these sculptures may be preserved and combined in various ways on simple or composite surfaces/ molds. Many of the resulting specimens appear to be morphologically quite distinct from each other. The form and distribution of particular “taphomorphs,” however, can be predicted from a knowledge of shell mineralogy and taphofacies. The different sculptures present on the three shell surfaces, and their wide range of taphonomic expressions, had not been recognized previously, resulting in the erection of three nominal taxa for this single species, based on different taphomorphs. It is not clear whether similar problems remain undetected in other multi-shell-layered invertebrate fossil groups.

Pectinids are the most abundant and widely distributed taxa in the Tertiary marine beds of Patagonia. Along with other very common molluscan species, they characterize five assemblages, from oldest to youngest: 1) the Oligocene Panopea sierrana– Parinomya patagonensis Assemblage; 2) the Late Oligocene–Early Miocene Jorgechlamys centralis–Reticulochlamys borjasensis Assemblage; 3) the Early Miocene Reticulochlamys zinsmeisteri–Struthiolarella patagoniensis–Pleuromeris cruzensis Assemblage; 4) the Early Miocene Pseudoportlandia glabra–Antimelatoma quemadensis Assemblage; and 5) the latest Early Miocene–earliest Middle Miocene Nodipecten sp.–Venericor abasolensis–Glycymerita camaronesia Assemblage. A brief analysis of the origin and composition of these Tertiary Patagonian molluscan faunas is provided. Striking compositional changes occurred through time, recorded mainly in the Late Paleocene, Late Eocene, Late Oligocene–Early Miocene, and Late Miocene.

Mexfusus rotundicostatus new genus and species is a neogastropod of uncertain affinities from the Late Cretaceous (Early Maastrichtian) Mexcala Formation of southern Mexico. It is characterized by strong, rounded, axial ribs, fine spinelets at the intersection of axial ribs and sharp spiral cords, subsutural cord, strong simple spiral cords, and an apparently smooth, glazed columellar lip. A possible second species is Peristernia conica Riedel, 1932 from the Coniacian of Cameroon.

The Mississippian ammonoids Polaricyclus conkini new species, P. ballardensis (Gordon, 1965), Winchelloceras knappi new species, and Cantabricanites? greenei (S. A. Miller, 1892) occur with Gnathodus texanus Zone conodonts near the base of the New Providence Shale Member of the Borden Formation in north-central Kentucky. Both ammonoids and conodonts indicate an early late Osagean (lower Keokuk equivalent) age corresponding to the middle or, more probably, the late Chadian (latest Tournaisian or early Viséan) portion of the Fascipericyclus–Ammonellipsites Zone.

The discovery of a new naraoiid nektaspid in the Upper Silurian (Pridolian) of southeastern Ontario significantly extends the range of this unusual group. Nektaspids are nonmineralized arthropods typical of Early and Middle Cambrian soft-bottom communities, but were thought to have become extinct in the Late Ordovician. The unique holotype specimen of Naraoia bertiensis n. sp. comes from a Konservat–Lagerstätte deposit renowned for its eurypterid fauna (the Williamsville Member of the Bertie Formation). Naraoia bertiensis lacks thoracic segments and is morphologically similar to Naraoia compacta from the Middle Cambrian Burgess Shale, save for the presence of a long ventral cephalic doublure and a subtly pointed posterior shield. To examine the phylogenetic relationships of the new naraoiid, we coded characters of the holotype specimen and of nine previously described nektaspids. The results confirm a sister taxon relationship between Naraoia compacta and Naraoia bertiensis and the monophyly of nektaspid forms lacking thoracic segments (family Naraoiidae). This latter group may have arisen from an ancestral segment-bearing form through heterochronic loss of thoracic segments early in the Cambrian. The disjunct occurrence of a naraoiid nektaspid in the Late Silurian resembles the reappearance of other “Lazarus taxa” that were thought to have been eliminated during mass extinction events. The naraoiid lineage survived the Late Ordovician biotic crisis, but in this case the “Lazarus effect” seems likely to be taphonomic in origin.

Despite their importance in breaking down lignified tissue today, much is still unknown about the role of mites in the fossil record, especially with reference to the Paleozoic–Mesozoic transition. This study examines permineralized peat from three localities in the central Transantarctic Mountains, ranging in age from Permian to Jurassic, for evidence of diversity and abundance of wood-boring mites. Evidence of mites, in the form of coprolites and tunnels in wood and other tissues, was found at all three localities; the Triassic site included more than 10 times as many wood borings as the Permian site. Our results supplement prior evidence of wood-boring mites during the Mesozoic and thereby fill in the known geologic range of this plant/animal interaction.

We characterized the skeletal crystallography of representatives of nine rhombiferan, three diploporan, and three paracrinoid species. Crystallographic data from these groups are similar to data from previous studies of crinoids, echinoids, and blastoids in that 1) orientations of c axes are consistent within species and within higher taxonomic groups; 2) c axes typically are oriented subparallel to the medial plane of their respective plates; and 3) the inclination of axes within the medial plane varies between taxa. Rhombiferan c axes are oriented normal to plate surfaces whereas diploporan c axes are tangential to plate surfaces. Paracrinoids more closely resemble diploporans in having irregular patterns of thecal plating but their c axes are approximately perpendicular to plate surfaces as in rhombiferans.

In contrast to c axes, a axes in all specimens show little regularity and cannot be distinguished from random orientations.

The rhombiferan Caryocrinites ornatus displays minor differences in the inclinations of c axes depending on the location of skeletal elements on the theca. Plates at the base of the theca have slightly aborally inclined axes, whereas distal plates have axes inclined slightly adorally. This pattern matches orientations in some early crinoids, suggesting similarities between rhombiferans and crinoids in development or skeletal construction.

Skeletal crystallography in various echinoderms can be compared in light of hypotheses of homology proposed in the Extraxial-Axial Theory (EAT). Skeletal elements homologized under the EAT do not correspond to any particular crystallographic axis orientation, suggesting that the homologies proposed in the EAT encompass significant underlying skeletal variation.

Remains of a large sea turtle, Terlinguachelys fischbecki n. gen. and sp., were recovered from paralic deposits of the Upper Cretaceous (Campanian) Aguja Formation in Big Bend National Park, Texas. T. fischbecki is a primitive protostegid that retains a constricted humerus, well ossified plastron and costals, prominent retroarticular process on the lower jaw, and long slender femora; however, it has some features, such as a prominent tubercle at the base of the scapular acromion process, found elsewhere only in derived leatherback sea turtles. The unique combination of primitive and derived traits in T. fischbecki illustrates further diversity among Cretaceous sea turtles and another case of parallelism common in sea turtle phylogeny.

The Antilocapridae was a diverse artiodactyl family present in some late Tertiary faunas of North America. In México, its Tertiary fossil record is poorly known. The antilocaprid material described in this paper was collected from the early Blancan fluvial deposits of the San Miguel de Allende Area, state of Guanajuato, México. It includes isolated upper and lower premolars and molars, dental series, and some rami fragments. The material is assigned to Capromeryx tauntonensis. The presence of this species in the early Pliocene of central México represents the oldest record in North America and extends its known geographic distribution from the northwestern United States to central México.