Lower to Middle Cambrian shales of the Mount Cap Formation in the Mackenzie Mountains, northwestern Canada, host a variety of Burgess Shale-type macrofossils, including anomalocarid claws, several taxa of bivalved arthropod, articulated hyolithids, and articulated chancelloriids. Hydrofluoric acid processing has also yielded a broad range of organic-walled fossils, most of which are derived from forms more typically known as shelly fossils; e.g., trilobites, inarticulate brachiopods, small shelly fossils (SSF), hyolithids, and chancelloriids. Organic-walled hyolithids include conchs, opercula and helens; the proximal articulation of the helens is erosive, suggesting that they were formed “instantaneously” and periodically replaced. Organic-walled chancelloriid sclerites exhibit a polygonal surface texture and an inner “pith” of dark granular material with distally oriented conoidal divisions; such a pattern is similar to that seen in the fibers of some modern horny sponges and points to a poriferan relationship for the chancelloriids. The robust nature but minimal relief of most of these fossils suggests that primary biomineralization was minimal.

A limited fauna of relatively simple, thin-walled, hexactinellid sponges, including moderately coarse-textured, funnellike Hexactinella(?) conica new species, fine-textured, tubular to branched Hexactinella(?) tubula new species, fragments of delicate Eurete goederti(?) Rigby and Jenkins, 1983, and Farrea(?) species, has been found in the Oligocene Lincoln Creek Formation on Canyon River, in the southcentral part of the Olympic Peninsula, Washington. These sponges dominate a chemosynthetic invertebrate assemblage that included the gastropod Provanna antigua Squires, 1995; the polyplacophoran Leptochiton alveolus (Lovén, 1846), and radiolarians. Most of the sponges are preserved as silica in a localized cherty and botryoidal, calcareous cement-filled limestone formed at bathyal depths by bacterial oxidation of methane at a cold seep. This is the third known report of sponges from ancient chemosynthetic deposits.

Well-preserved, laterally flattened, farreid hexactinellid sponges of the new species Farrea rugosa have been recently discovered in the upper Miocene Puente Shale in the Peralta Hills in southeastern Anaheim, Orange County, California. This is the first farreid sponge reported from the Miocene of California and is one of the few Miocene sponges reported from North America. The cluster is of upward bifurcating, moderately complex sponges in which branches are regularly rugose and skeletons are each a single layer of dictyid net, with aborted proximal and distal rays in the otherwise laterally fused quadruled skeleton of original silica. The sponges occur in pinkish brown sandy siltstone in the limited exposure beneath older alluvium that blankets much of the local area.

The late Llandovery through late Ludlow sequences of the stable carbonate platform of Gotland (Baltic Basin; western side of the Silurian paleocontinent Baltica) and the carbonate ramp of the Welsh Borderland area in England contain a richly fossiliferous fauna of atrypid brachiopods, including more than 60 species. This was a time of diversification for the atrypids in the tropical equatorial latitudes, with new lineages appearing for the first time that were to dominate the Devonian Period. Included in this burst of new groups was the ribbed atrypid group, the Plectatrypinae (new subfamily), which quickly led to the first spinose atrypids, the Spinatrypinae. For the Plectatrypinae, a new subgenus and species, Plectatrypa (Gutnia) capidula, and a new genus, Xanthea, are described. The evolution of expanded growth lamellae and frills on the shell at this time led not only to the growth of large shells assignable to Atrypa, but also to the rise of affiliated ribbed taxa, such as the perireefal and reefal genus Endrea echoica new genus and species (Wenlock-Ludlow). The nature, affinities and taxonomy of the smooth atrypid Lissatrypa obovata (Sowerby) from the U.K. are also clarified, indicating that the type species for the unrelated genus Glassia needs to be revised.

Following the mass extinction event at the end of the Cretaceous, the marine molluscan faunas of the high southern latitudes underwent a marked period of diversification during the early Paleocene. The appearance of four new species belonging to the new genus Seymourosphaera, tentatively placed in the subfamily Pseudolivinae, from the lower Paleocene strata of Seymour Island, Antarctic Peninsula, clearly illustrates the post-Cretaceous extinction diversification. The abrupt radiation of the buccinids during the early Paleocene, was also apparently related to geographic isolation of Antarctica during final breakup of Gondwana. Comparative analysis of shell morphology of Seymourosphaera, new genus reveals close morphologic similarities, not only with taxa within Pseudolivinae, but also with several genera and subgenera belonging to the families Buccinidae and Nassariidae. However, incompleteness of the fossil record and a “generalized” shell morphology make difficult establishment of unequivocal phylogenetic relationships for Seymourosphaera. A taxonomic review of most closely related, and possibly ancestral genus Austrosphaera Camacho, 1949, is provided. The following new species of genus Seymourosphaera new genus are described: Seymourosphaera bulloides new species, S. subglobosa new species, S. depressa new species, and S. elevata new species.

Iheringinucula, a new Tertiary genus of the family Nuculidae, is proposed. This taxon is known only from the Patagonian region (Argentina), and its range is from the late Eocene to the early Miocene. Two species are known: Iheringinucula tricesima (Ihering) from the Monte León Formation (upper Oligocene-lower Miocene) and Iheringinucula crassirugata new species from the San Julián Formation (upper Eocene-lower Oligocene?) and the Monte León Formation.

Crassadoma monroensis new species (Mollusca: Bivalvia: Pectinidae), from the lower upper Pliocene Ochopee Limestone Member of the Tamiami Formation of southern Florida, is the first undoubted member of the genus Crassadoma Bernard, 1986, to be discovered in the Neogene on the eastern side of the Americas. The new species was likely byssate, not cemented, and fills the geographic gap between ancestral members of the tribe Crassadomini in the eastern Atlantic and Crassadoma gigantea, the giant cemented species that lives along the western shores of North America.

The marine offshore shelf mudstones of the Early Cambrian Buen Formation at Sirius Passet, North Greenland, contain a rich Konservat-Lagerstätte which includes abundant well-preserved material of the bivalved arthropod Isoxys volucris new species. The new material confirms Isoxys Walcott, 1890 as a component of the earliest arthropod faunas worldwide. Isoxys species are known from the Early Cambrian of Spain, Siberia, South Australia and Southwest China and also from the Early to Middle Cambrian of Laurentian North America. Isoxys occurs in the Redlichiid, Bigotinid and Olenellid trilobite faunal realms but is restricted to within tropical/subtropical regions, attesting to possible paleolatitudinal controls on its distribution. Isoxys resembles some phyllocarid and bradoriid arthropods but without knowledge of its soft-parts the affinity of the genus remains uncertain.

A model for crinoid plate circlet homologies is proposed based on a tricyclic (four-circlet) aboral cup, with Aethocrinus the characteristic tricyclic crinoid. The plate circlets in the aboral cup of Aethocrinus, from bottom to top, are lintels (named herein), infrabasals, basals, and radials. In this model, traditional interpretation is maintained for the aboral cup plates of most crinoids. Cladids, flexibles, articulates (primitively), and diplobathrid camerates are dicyclic and are composed of infrabasal, basal, and radial circlets. Monobathrid camerates are monocyclic, and they have basal and radial circlets. Disparid plate circlet homologies are reinterpreted. Among disparids, “basals” are lintels, “inferradials” and “radials” are infrabasals, and “superradials” are radials.

The “Law of Wachsmuth and Springer” is judged to be a relationship that has most fidelity applied to lumen angles. This “law” is considered to be only a consequence of development and not an invariable basis by which to determine plate homologies. In the model presented here, plates cannot be shifted around after the juvenile calyx is sutured, and arms may grow on either radials or infrabasals, whichever plates are at the top of the cup when arms begin to grow.

A new isocrinine species, Nielsenicrinus japonicus, is described from the Maastrichtian of western Kyushu, Japan. This is the first confirmed occurrence of this genus outside Europe. Three isocrinine genera, Nielsenicrinus, Cainocrinus, and Teliocrinus, have a common arrangement of ligamentary articulations in the primibrachials and secundibrachials. These taxa possibly constitute a single lineage since the Early Cretaceous through the Recent, and they were known only from Eurasia, or from Indian Ocean (Teliocrinus).

A new classification is proposed for late Paleozoic Edrioasteroidea (Echinodermata), separating forms with the advanced clavate thecal design from those with the ancestral pyrgate thecal design, and a new Subfamily Discocystinae is erected to receive the clavate agelacrinitid edrioasteroids. Lepidodiscus Meek and Worthen is restricted to the pyrgate type species L. squamosus (Meek and Worthen) and two unnamed species, whereas the clavate L. laudoni (Bassler) is assigned to Clavidiscus, new genus. The clavate Discocystis priesti Strimple and three new species, Hypsiclavus kinsleyi, new genus and species, Hypsiclavus huntsvillensis, new genus and species, and Hypsiclavus guensburgi, new genus and species, are placed in Hypsiclavus, new genus. Bostryclavus, new genus, is erected to receive Echinodiscus sampsoni Miller. A redescription of Discocystis kaskaskiensis (Hall) and a diagnosis of Spiraclavus Sumrall are included for completeness.

A new genus and two new species of late Paleozoic edrioasteroids, Giganticlavus bennisoni and G. gelasinus, are described from the Early Pennsylvanian of Oklahoma and New Mexico. Giganticlavus differs from other clavate edrioasteroids by its large size, extreme ambulacral length and ambital overlap, extreme thickness of interambulacral and recumbent zone plates, and the tessellate nature of the recumbent zone plating. The extreme length of ambulacra and thickness of the plating are interpreted as adaptations for increased size and rigidity.

Ptyctodonts from the Upper Devonian Martin Formation on Mt. Elden, northern Arizona, were hitherto known only from tooth plates ascribed to Ptyctodus bradyi. Recent collections include dental elements of P. bradyi as well as body and skull plates and dental elements of a previously unknown ptyctodont, described here as Denisonodus plutonensis new genus and species. Comparison with other ptyctodonts suggests that the new genus has close affinities to other North American forms. As the holotype of Ptyctodus bradyi has been lost a neotype is designated here.

As part of a study of vertebrate trackways in the cross-stratified Coconino Sandstone (Permian) of northern Arizona, trackways made by living salamanders under different substrate conditions were compared. The sample of 230 trackways of the western newt, Taricha torosa, included ten combinations of the following substrate characteristics: 1) sediment: muddy or of fine sand; 2) attitude: level or sloped (25 degrees); 3) moisture content: dry, damp, wet, or submerged.

Trackways in wet mud produced the most accurate representation of the number of toes per foot and the arrangement of toes. All other conditions studied yielded a reduced average number of toes per foot, and a large sample was needed before the data had the potential to indicate the true structure of the trackmaker's feet. Trackways made on sloped, submerged mud or sand, sloped, dry sand, and sloped, damp sand rarely included the full complement of toes. The positions and orientations of the toe marks were distorted if the animals were walking underwater or on sloped, damp sand. Trackways on the slopes of cross-stratified deposits make reliable identification of the trackmaking animals exceptionally difficult.

The large number of ichnospecies in Permian vertebrate ichnology literature is often a result of a failure to recognize substrate or gait-controlled variations in trackway morphology. Additionally, regional studies were often performed in isolation from studies in other areas. Nomenclatural priority applies to the names first assigned to trackways from the Corncockle and Locharbriggs Sandstone Formations (Permian) of Dumfries and Galloway, Scotland. Only one ichnogenus, Chelichnus, and four ichnospecies are recognized here and all had been identified in the studies of Jardine in 1850 and 1853. Chelichnus represents tetrapod trackways with rounded manus and pes impressions, subequal in size with up to 5 short digits where preservation is complete. The normal trackway pattern shows a pes pace angulation of up to 90° with the manus and pes being impressed close together or possibly with a slight overlap of the manus by the pes. Chelichnus bucklandi shows a pes size of 10 to 25 mm, C. duncani shows a pes size of 25 to 75 mm, C. gigas shows a pes size of 75 to 125 mm, and C. titan displays a pes size exceeding 125 mm in length. This restriction to four ichnospecies is more in accord with the low faunal diversity to be expected from an eolian environment of Late Permian age than was the former taxonomic classification. The Permian ichnofaunas of the Coconino Sandstone of Arizona and the Cornberger Sandstein of Germany are also composed largely of these four ichnospecies.

Previously described upper and lower molars from the Fort Union Formation (Swain Quarry, Wyoming) are referred to Swaindelphys cifellii new genus and species. This taxon is assigned to the subfamily Herpetotheriinae, family Didelphidae. These molars were originally referred to a new, unnamed species of Peradectes (subfamily Peradectinae), with similarities to P. pusillus (now Thylacodon pusillus) and P. elegans. However, upper molars differ from these taxa in being dilambdodont, in possessing more strongly developed stylar cusps, especially on M2 and M3, and in having a protocone that is shifted anteriorly. These characters suggest similarity to taxa such as Peratherium (subfamily Herpetotheriinae, family Didelphidae), rather than Peradectes. The assignment of the lower molars from Swain Quarry is more problematic: these molars are similar to the holotype Thylacodon pusillus in that the entoconid and hypoconulid separated by a strong notch; however, the Swain Quarry lower molars differ in being smaller overall and possessing an anteroposteriorly shorter talonid. These lower molars are similar to didelphid lower molars in having a hypoconulid that is lower than the entoconid (these are subequal in height on lower molars of Peradectes), but differ from didelphid lower molars in that the hypoconulid does not form a low, posteriorly projecting shelf. Nevertheless, the upper and lower molars from Swain Quarry are considered to belong to a single taxon, and with the assignment of the Swain Quarry materials to the subfamily Herpetotheriinae, the geological range of this subfamily is extended from the early Eocene back into the middle Paleocene (Torrejonian, or To3).

A new genus and species of thylacinid, Muribacinus gadiyuli, is described from Miocene deposits of Riversleigh in northwestern Queensland. Muribacinus gadiyuli shares six character states associated with carnassialisation common among thylacinids, but is uniformly less derived for each. The closest affinities of this species lie with another plesiomorphic thylacinid from Riversleigh, Nimbacinus dicksoni. Two previously recognised thylacinid synapomorphies are reconsidered in the light of new evidence. A growing body of molecular and fossil data indicates that the modern dasyurid radiation is a relatively recent phenomenon. Character analysis suggests that no reliable dental synapomorphies define the Dasyuridae at present. It is proposed that a number of plesiomorphic late Oligocene and Miocene taxa previously considered as dasyurids be regarded as Dasyuromorphia incertae sedis pending the identification of shared derived dental characters for the family, or the discovery of more complete material.

This paper describes the petrosal (periotic) and the inner ear of Herpetocetus sp., an archaic mysticete whale (Mysticeti, Mammalia) from the Yorktown Formation (Pliocene) of North Carolina, USA. Parsimony analysis of 28 petrosal characters of Herpetocetus sp. and 11 other cetacean taxa supports the monophyly of mysticetes and the division of odontocetes and mysticetes. The in-group taxa of this analysis are: Herpetocetus, Parietobalaena, Pelocetus, Balaenidae, Eschrichtius, and Balaenopteridae. Odontocetes and the archaeocete Zygorhiza were used as successive outgroups to root phylogenetic trees and to establish character polarities. Among the modern mysticetes, the Balaenopteridae (rorquals) and the Eschrichtiidae (gray whales) are more closely related to each other than either is to the Balaenidae (bowhead and right whales). Several Miocene “cetotheriid” mysticetes and balaenids share some resemblance in the petrosal, suggesting their affinities. Quantitative information of the inner ear of Herpetocetus sp. was obtained by serial sectioning and computer graphic reconstruction. Herpetocetus sp. is much less developed than odontocetes in the cochlear structures that are crucial for high frequency hearing. Some cochlear structures in this fossil mysticete resemble more closely the non-echolocating modern mysticetes than early fossil toothed whales, indicating a possible specialization in low frequency hearing. This suggests that the archaic mysticetes of the Miocene and Pliocene did not have high frequency hearing necessary for echolocation. Herpetocetus sp. is similar to modern mysticetes but different from odontocetes in the spherical shape of the vestibule.

Upper Pennsylvanian dysoxic marine shales of midcontinent North America yield permineralized remains of apparently extrabasinal vegetation. A large percentage of the plants are surprisingly unlike the well known swamp, fluvial and lacustrian floras of the late Paleozoic paleotropics, revealing numerous aspects of the morphology, anatomy and reproductive biology of plants that may have been ancestral to the dominant taxa of the Mesozoic. Included among the assemblages are ovulate coniferophyte remains that demonstrate the occurrence of vojnovskyalean seed plants in equatorial Euramerica. Specimens consist of simple ovulate cones that are more-or-less clustered along eustelic stems in the axils of helically arranged, strap-shaped leaf bases, and are described as Sergeia neuburgii new genus and species. Individual cones are up to approximately 2 cm long and 1.5 cm in maximum diameter, with helically arranged scales and sporophylls that diverge from a eustelic axis. Scales occur in the basal region of the cone, and are laminar and pointed. Sporophylls are borne distally. One specimen shows about 45 sporophylls, each of which terminates as one erect ovule. Most of the other cones have abraded apices, and terminate in relatively terete foliar appendages that are interpreted to be sporophyll bases. Ovules are flattened and winged, approaching 180° rotational symmetry. Integument histology, vascular tissue distribution and pollen chamber structure are similar to those of cordaiteans and callistophytalean seed ferns. Sergeia adds to the number of late Paleozoic conifer-like plants that do not conform to the Pinopsida as traditionally circumscribed, and poses additional questions to assumptions of monophyly for coniferophytes and for conifers sensu lato.

Distinctive galls have been found on a fossil oak leaf from the Miocene Gillam Springs Flora of Washoe County, Nevada. The described galls are located on the leaf surface of Quercus hannibali Dorf, an analogue of the modern species Q. chrysolepis Liebmann. Similar galls are found on extant Quercus, but the fossils seem distinctive enough to warrant description as Antronoides schorni new genus and species. The occurrence of Antronoides schorni coincides with a rapid episode of change from a mesic to a more xeric habitat, with a concomitant shift from an oak-dominated to a conifer-dominated paleoflora. Recent work suggests that speciation and radiation of galling insects is highest in xeric environments, possibly due to decreases in rates of parasitism and disease. This pattern has been documented for modern galling insects and fits the qualitative fossil evidence we present. These galls also support the hypothesis that cynipids in the Antron group originated in Nevada or eastern California and migrated from their point of origin to their current range in the Sierra Nevada and Coast Ranges.