The distinctive cheilostome bryozoan Stictostega durhami Shaw, 1967, from the Upper Campanian Ozan Formation of Arkansas, is redescribed and its relationships are reconsidered. Originally interpreted as a hippothoid ascophoran, the presence of a cryptocystal frontal shield and other characters suggest that it is a coilostegan anascan. Pores in the frontal shield are inferred to have served for the passage of parietal muscles (or their ligaments), which operated on the frontal membrane to raise hydrostatic pressure and protrude the lophophore in the same way as recently demonstrated in living Macropora. Stictostega is provisionally interpreted as a stem-group macroporid.

Forty species of gastropods (six of them new: Calliomphalus (Planolateralus) mexcalensis, Nododelphinula diminuta, Potamides temalacensis, Ptychopotamides ancestralus, Amaurellina guerrera, and Drilluta gloriae), and 13 species of bivalves are described from the lower Maastrichtian marls of the basal Mexcala Formation from Guerrero State, southern Mexico. Age interpretation was based on planktic foraminiferans. Associated fauna includes planktic and benthic foraminiferans, ostracods, solitary corals, crustaceans, echinoids, and vertebrates. The distribution of bivalve and gastropod species suggests that this area has affinities with the Gulf Coast Plain Province of the United States, although some species also are reported from the Middle East, Europe, and South America.

A new trigonotarbid arachnid, Gigantocharinus szatmaryi new genus and species, is described from Upper Devonian (Late Famennian) sediments in Pennsylvania. Devonian trigonotarbids were known before from only a single North American locality and several European ones. The new trigonotarbid occurs in what had previously been a significant time gap between the faunas of the Middle Devonian and the late Carboniferous. Gigantocharinus szatmaryi is assigned with some hesitation to the family Palaeocharinidae.

Well-preserved stem remains of the three crinoid species Qingyanocrinus kueichounensis (Dubatolova and Shao, 1959), Bangtoupocrinus kokeni n. gen. n. sp. and Silesiacrinus parvus n. sp. from the lower Upper Anisian (Middle Triassic) of Qingyan, Guizhou Province, southwestern China, are described. The former two taxa originally were described as one species, Entrochus rotiformis Koken, 1900, which is a nomen dubium. The two new genera Qingyanocrinus and Bangtoupocrinus are established. Bangtoupocrinus and Silesiacrinus are the earliest known millericrinid genera. For these Middle Triassic millericrinids, the new family Bangtoupocrinidae, comprising the new subfamilies Bangtoupocrininae and Silesiacrininae, is defined. The strongly cirrate genus Qingyanocrinus is assigned to the new family Qingyanocrinidae, whose systematic position is uncertain.

In all three species, the morphological features of the columnals characteristically vary in different parts of the stems. The millericrinids were cemented to (secondary) hard substrates by distal encrusting holdfasts. Qingyanocrinus kueichounensis most likely lived on soft substrates and for attachment made use of its rootlike distal stem end and cirri. Stems of Bangtoupocrinus kokeni regenerated after breakage show that these crinoids were able to continue living in spite of the traumatic loss of their basal fixation. Juvenile Encrinus cf. liliiformis Lamarck, 1801, and other invertebrates utilized the crinoids and their skeletal remains as substrates for attachment.

In the first broad survey of skeletal crystallography in fossil crinoids, we examine 10 Ordovician species representing five orders and apply crystallographic data to questions of crinoid phylogeny, homology, and development. Orientations of c crystallographic axes in the large calcite crystals that form the skeletal plates of the crinoid calyx vary systematically according to the position of each plate on the calyx. Plates lower on the calyx have axes more inclined toward the stem attachment than are axes from plates higher on the calyx. Although most specimens display this general pattern, exact orientations vary widely between species with no discernible relationship to phylogeny. Furthermore, the topological pattern of variation does not correlate with the order of addition of plates to the calyx during growth.

Lack of a phylogenetic signal among diverse crinoids early in the clade's history implies that crystallographic data will be of limited use to high-level phylogenetic studies within crinoids. Neither does skeletal crystallography strongly favor any of several competing interpretations of homologies among major crinoid calyx plates. Crystallographic data are informative, however, for some minor skeletal plates. Brachial plates have c axes that roughly parallel the surface of the plate, whereas interbrachial plates have perpendicular c axes, suggesting that distinct generative processes produce these plates. Anal plates have orientations similar to interbrachials, suggesting similar developmental mechanisms.

Although c axes have regular orientations relative to plate morphology within a specimen, a axes show extensive intraspecimen variability with respect to plate morphology.

The attachment of a small edrioasteroid to the nonperiproctal surface of a small specimen of the pleurocystitid rhombiferan Amecystis has implications for the life posture of pleurocystitids and indicates that Amecystis was epifaunal. Articulation of the preserved portions of both thecae indicates that the edrioasteroid and Amecystis were alive at or very near the time of burial and that the edrioasteroid used the Amecystis theca as an attachment surface. Other examples of edricasteroids attaching to live organisms are known suggesting that an edrioasteroid attached to a live rhombiferan is not highly unusual. The position of the edrioasteroid on the rhombiferan suggests that Amecystis was oriented with the anal side down in life and that this pleurocystitid was fully epifaunal.

An examination of Devonian through Pennsylvanian postibullinid edrioasteroids indicates the presence of two clades in the monophyletic subfamily Postibullinae, new subfamily. Postibulla is characterized by the presence of a posterior oral protuberance and a cover plate pattern with three primary plates and includes Postibulla legrandensis, P. lukei, P. keslingi, P. neglecta, and P. alabamaensis new species. Parapostibulla new genus is characterized by double biserial cover plates, the lack of the posterior oral protuberance, and an unusual hydro-gonopore, and includes Parapostibulla hybolopus (Fraunfelter and Utgaard, 1970), P. murphyi new species and Parapostibulla species A. Additional poorly-preserved edrioasteroids are illustrated from the Missourian and Virgilian of Kansas and Iowa that are the youngest known from North America.

An investigation of the morphology and astogenetic pattern of isolated specimens of two species of Paraclimacograptus permits an assessment of the phylogenetic relationships of this genus. Forty-two specimens previously assigned to Paraclimacograptus innotatus ssp. isolated from turbiditic limestone from the Southern Urals of Russia (Cystograptus vesiculous Zone) and limestone concretions from the Canadian Arctic (Coronograptus cyphus Zone) were examined using the method of infrared video microscopy. Paraclimacograptus has a Pattern H astogeny and is therefore a member of the family Normalograptidae. At least three species can be distinguished using biometric criteria, P. innotatus, P. exquisitus, and P. obesus. Rhabdosomal characteristics of Paraclimacograptus indicate that it is phylogenetically related to early species of the genus Neodiplograptus. The point of divergence of the proximal thecae is defined by the interfingering of fuselli of markedly different widths. This suggests that fuselli were not necessarily secreted at a constant rate. In addition, this pattern of fusellar interfingering is here regarded as more consistent with a pterobranch mode of secretion than with a model of growth under an enveloping extrathecal mantle.

Collections from upper Ibexian (Tulean Stage) rocks of western United States, from the Canning Basin in western Australia, and from the Argentine Precordillera contain a seximembrate apparatus of multidenticulate conodonts whose elements have been included by authors in species of Prioniodus Pander, 1986, and Reutterodus Serpagli, 1974. The individual elements as well as the complete apparatus are not consistent with assignment of the species to either of these genera or to any other extant genus. A new generic name, Stiptognathus Ethington, Lehnert, and Repetski, is proposed with Reutterodus borealis Repetski, 1982, as type species. The apparatus consists of Pa, Pb, Sa-c, and M elements; the genus represents either the Prioniodontidae or the Periodontidae.

The Upper Olentangy Shale of Ohio, a green pyritic shale interbedded with thin dark gray shale beds, disconformably overlies the lithologically similar Middle Devonian Lower Olentangy Shale. The muds were deposited in a quiet offshore environment on the distal margin of the Appalachian Basin during the Late Frasnian through Early Famennian. The Upper Olentangy Shale contains abundant and diverse conodonts of MN Zone 13 and the Middle triangularis Zone. The Frasnian-Famennian boundary is 4-8 cm below the base of the Huron Shale at the Olentangy Shale type section in Delaware, Ohio. The boundary interval is a green shale containing a mixed highest Frasnian (e.g., Palmatolepis bogartensis, P. linguiformis) and lowest Famennian (e.g., P. delicatula, P. subperlobata, P. triangularis) conodont fauna. An ash horizon, pyritic bed, finely laminated dark shale, and a thin green-blue shale comprise the upper 3 cm of the Olentangy, and contain a conodont fauna indicative of the Middle triangularis Zone.

All aspects of conodont paleontology rely on the identification and description of homologous anatomical units or elements. But the current schemes of anatomical notation and terms for orientation were formulated at a time when little was known of conodont anatomy or skeletal architecture, resulting in some confusion and difficulties in their application. With improving knowledge of conodonts, these problems are becoming increasingly acute.

In an attempt to address current problems, we introduce new terms for orientation in conodonts and their elements, and a modified scheme of anatomical notation. The principal axes of the conodont body are identified as rostrocaudal, dorsoventral, and mediolateral, with opposite lateral sides designated dextral and sinistral. Anatomical notation is defined according to topological relationships between elements with reference to the principal axes of the body and takes the form of letters with numeric subscripts (e.g., P1, P2, S0-S4). The ozarkodinid apparatus serves as a standard, but the Pn-Sn scheme can be applied rigorously to all taxa that are known from natural assemblages or where an hypothesis of topological homology can be inferred from secondary morphological criteria.

The Yahatinda Formation of southern Alberta and British Columbia consists of a series of channels cut into lower Paleozoic rocks and represents deposition in marine to littoral environments across a major regional unconformity. The age of the beds is late Givetian based on spore assemblages and plant macrofossils. A vertebrate fauna from the formation is described here for the first time and includes Heterostraci (two new species of tuberculated pteraspidids), Placodermi (an antiarch and the arthrodire Holonema together with indeterminate arthrodires), Osteolepiformes, and Porolepiformes. This report documents for the first time that pteraspidids, considered to be organisms characteristic of the Lower Devonian elsewhere, lingered to the end of the Middle Devonian in western North America. This fauna is similar to others occurring further south in the western United States.

The sphenodontian Ankylosphenodon pachyostosus new genus and species is the second unusual sphenodontian reported from the Albian deposits of the Tlayua Formation, near Tepexi de Rodríguez, Central Mexico. The skeleton is robust with pachyostotic ribs and vertebrae. Unique long teeth are ankylosed deep into the lower jaw extending close to the edge of the Meckelian canal. Long teeth with open roots, the lack of worn-out teeth, and the presence of posterior wear surfaces exhibiting dentine suggest that tooth growth was continuous. These features combined with a propalinal action of the deep lower jaw suggest herbivory. Herbivorous specializations of Ankylosphenodon are different from the laterally expanded teeth of Toxolophosaurus and Eilenodon and may have evolved to prevent total tooth loss, a feature which is observed in sapheosaurs. A pachyostotic skeleton, a delay of the ossification of the epiphyses, and a solid structure of the vertebral column could be related to a none obligated aquatic behavior. These specializations differ greatly from those of other aquatic sphenodontians such as Pleurosaurus and Palaeopleurosaurus. A stout skeleton with swollen horizontal zygapophyses suggests affinities with sapheosaurs; however, cladistic analysis support sister-group relationship with Toxolophosaurus and/or Eilenodon on the basis of shared propalinal jaw action and deep jaws. The presence of two unique sphenodontians in the Tlayua Quarry suggests the presence of an area for the diversification of lepidosaur reptiles. The late presence of sphenodontians in the Albian also suggests that this area was a refuge for archaic forms at the time.

Predominantly horizontal, gently curved to slightly sinuous traces constituting uniserial rows of imbricated, subspherical sediment pads occur in Pennsylvanian tidal-flat facies of eastern Kansas. These traces exhibit a complex, actively filled internal structure. The presence of a median tunnel enveloped by overlapping pads of reworked sediment indicates that these biogenic structures should be included in the ichnogenus Nereites MacLeay in Murchison, 1839. A new ichnospecies, N. imbricata, is erected. Externally, Nereites imbricata differs from the other Nereites ichnospecies by the large, tightly packed, imbricated pads that commonly result in an annulated appearance on bedding-planes. Internally, obliquely arranged, arcuate laminae envelope the median tunnel and tend to follow the outline of the external semispherical pads. Additionally, the behavioral pattern reflected by N. imbricata is less specialized than that of the other Nereites ichnospecies. Eione monoliformis Tate, 1859 resembles N. imbricata in general appearence, but lack the diagnostic Nereites internal structure, and is invariably preserved as positive epireliefs. Occurrence of Nereites imbricata as both median tunnels surrounded by reworked sediment (Nereites preservation) and uniserial rows of imbricated sediment pads (Neonereites preservation) supports the notion that Neonereites Seilacher, 1960 is a preservational variant of Nereites. The ichnogenus Nereites is an eurybathic form and is a common component of Paleozoic shallow-marine facies.

The occurrence of amber in Sierra de Cantabria (álava, Basque Country) has been known for more than two decades but biological inclusions have only recently been found. The existence of crustaceans (amphipods and isopods), chelicerates (acari and arachnids), 12 orders of insects, and several bird feathers are reported in this preliminary study. In addition, there are leaf remains, molluscs, and a fair number of inorganic inclusions.

Pollen analysis of the clastic series indicates an age between upper Aptian—middle Albian, which allows an assignment of this stratigraphic unit to the Nograro Formation. Chemical analysis indicates that the amber has high maturity, which reflects its Cretaceous age. Chemical composition analysis also indicates an araucariacean origin, which is corroborated by pollen found within the amber deposit.

This new fossil site provides information for the reconstruction of paleocommunities of arthropods and sedimentary environments in the extreme south of the Basque-Cantabrian Basin during the Lower Cretaceous, characterized by coniferous forests with an understory of vascular cryptograms. Some of the identified arthropods add to the fossil record for various groups that are poorly known or unknown for this time period. This Lagerstätte constitutes one of the most important deposits of Mesozoic amber in the world.

An enigmatic encruster from the Upper Ordovician rocky shore exposed near Churchill, Manitoba, was recently described by Johnson et al. (1998). The specimen was found attached to a quartzite boulder enclosed in carbonate matrix. The matlike, calcareous fossil consists of densely packed, vertical, cylindrical columns with upward-radiating structures issuing from their centers. It was identified as a new genus and species, Storeacolumnella hudsonensis, of uncertain taxonomic affinity but with possible characteristics of sponges and calcareous green algae. In particular, the radiating structures within columns were compared with spicules of a sclerosponge and with the siphon system of siphonous green algae.

Fossil vertebrates have been described from the Paleocene of Big Bend National Park, Brewster County, Texas, by Wilson et al. (1952), Wilson (1967), Schiebout (1973, 1974), and Standhardt (1986). These studies focused on the mammalian component of the fauna, although crocodylian and chelonian remains are known. Schiebout (1973) referred a partial dentary to Diplocynodon. Teeth in the Black Peaks Formation were referred to Allognathosuchus by Straight (1996); Standardt (1986) discussed isolated crocodyliform teeth from across the Cretaceous-Tertiary Boundary in this area, but did not assign any of them to named taxa. Brochu (1996) briefly reviewed more complete remains, which were found to include an alligatorid and a member of Borealosuchus. The giant crocodylian Deinosuchus and a goniopholidid are known from underlying Cretaceous sediments (Rowe et al., 1992), and overlying Eocene units are known to preserve remains of the ziphodont taxon Pristichampsus (Busbey, 1986).