The Lower Cambrian Shuigoukou Formation of Xichuan, Henan province, China, yielded phosphatized instars belonging to the protolenid Ichangia ichangensis Chang, 1957, and two undetermined taxa. With relatively simple body plans, the three larval forms resemble each other to some extent, and protaspides of I. ichangensis show general similarities to those of the ellipsocephalid Palaeolenus lantenoisi Mansuy. However, their early ontogenetic processes exhibit subtle yet distinct differences. One group of unassigned protaspides possesses a sagittal glabellar furrow and protomarginal spines with branching extremities. The other unassigned protaspides bear especially long genal and protomarginal spines. The detailed preservation of these larvae reveals delicate structural variations that help provide a framework for evaluating relationships among Early Cambrian trilobites.

Compared to their Recent counterparts, fossil abalone are rare and poorly known. Their taxonomy is problematic, because most of the 35 fossil species have been described from single specimens and shell characteristics of Recent species are extremely plastic. Thus, the use of fossil species in phylogeny is questionable. Abalone first appear in the Upper Cretaceous (Maastrichian) with one species each in California and the Caribbean, are unknown in the Paleocene, and appear again in the late Eocene and Oligocene of New Zealand and Europe. They are regularly found from the late Miocene to the Recent in tropical to temperate regions worldwide. Most records are from intensely studied areas: SW North America, Caribbean, Europe, South Africa, Japan, and Australia. Despite their highest present-day diversity being found in the Indo-Pacific, their scarcity in the fossil record in this region is remarkable. The family may have originated in the central Indo-Pacific, Pacific Rim, or Tethys. An extensive list of all known fossil records including new ones from Europe and western North America is given. Fossil and Recent abalone both apparently lived in the shallow, rocky sublittoral in tropical and temperate climates. No on-shore/off-shore pattern is detected.

The Walcott-Rust Quarry, at Trenton Falls, New York, has yielded a large number of well-preserved, fully articulated fossils from the lower third of the Middle Ordovician Rust Formation, Trenton Group. Along with three species of the more common trilobites from the Trenton Group, fourteen species of rare and uncommon trilobites are found within a thin package of micritic limestones and shales. The first trilobites with preserved appendages, Ceraurus pleurexanthemus Green, 1832 and Flexicalymene senaria (Conrad, 1842), were described from one layer from this quarry. Unique specimens of Isotelus walcotti UIrich in Walcott, 1918, and Sphaerocorphe robusta Walcott, 1875, were found in the next higher bed. Re-excavation of the quarry yielded information about the taphonomy of the trilobites and stratigraphy of the trilobite layers. Nearly half of the beds surveyed (n = 50) yield direct evidence of obrution (i.e., rapid post-mortem or live burial) of benthic organisms. Unusual anaerobic microenvironments in partially enrolled trilobites of the Ceraurus layer facilitated very early calcification of appendages and other soft parts.

Pleurocystites strimplei new species, from the Galena Group of Iowa and Minnesota, is closely related to P. squamosus Billings from the Appalachians and Michigan. Numerous specimens provide information about growth, living habits, functional morphology, and respiration. The development of P. strimplei n. sp. is largely isometric with several exceptions. New dichopores form throughout ontogeny. Length of the dichopores and the area available for respiration are characterized by strong positive allometry relative to the volume of the animal. The length of the distal stem increases with respect to the size of the theca. During life the aboral side faced up. Some animals were largely covered by a thin layer of sediment whereas others lay directly on the seafloor. The orientation of the brachioles is most consistent with deposit feeding. Quantitative models of respiration suggest that the pectinirhombs accounted for over half of the needs of youngsters but this contribution falls to about 38 percent in adults. Respiration by the surface area of the theca and the water vascular system provide small amounts of oxygen, especially for animals living on the surface of the seafloor. Cloacal pumping or a similar type of respiratory device probably furnished the remainder of the oxygen required by P. strimplei n. sp. The morphometric data in conjunction with parameters taken from Recent oceans and echinoderms produce a plausible respiration budget, which is affected by size, age, allometry, and living orientation.

A new, low-density trilobite body cluster from an Upper Ordovician Kope Formation mudstone in the Cincinnati region is characterized by well-preserved, articulated specimens. This cluster is polytaxic, size-segregated, and shows an unusual variety of flexure postures in the most common taxon, Flexicalymene aff. granulosa. Specimens show internal pyritization and associated pyritefilled tubular burrows, and were preserved by rapid deposition of mud from a sediment-laden flow. Size-segregation among species, but size-consistency within species, coupled with sedimentological data and apparently haphazard body orientation data, suggest that the trilobites represent a biological association, rather than the product of mechanical sorting. While the majority of specimens are inverted, many are dorsal-up, and some are inclined to bedding. Postures include prone (i.e., nonflexed), simple dorsal or ventral flexure, and complex stances that combine both dorsal and ventral flexure. Flexure pattern appears largely unrelated to sediment compaction. We interpret the cluster as an association of live trilobites that were entombed in situ. Specimens may have inverted prior to burial as a behavioral posture, or as a response to onset of burial. The animals were likely preserved in the process of escaping, as they tried to free themselves from being buried. This is in contrast to the tightly enrolled stance in some trilobites, especially other Flexicalymene, commonly associated with rapid burial events, and indicates a new behavioral aspect of trilobite paleobiology. The distribution of associated burrows suggests that the rotting carcasses attracted scavengers.

Phosphatic microfossils including copious microvertebrates and conodont elements indicative of the upper Icriodella discreta–Icriodella deflecta Zone (Aeronian) are found in a single bed of the Hendricks Formation, Burnt Bluff Group, Sturgeon Bay, Wisconsin. Scales of thelodonts, including Loganellia sp. cf. Loganellia siberica Karajute-Talimaa, 1978, and rare Valyalepis crista Turner (in Turner and Nowlan, 1995) predominate among the microvertebrate remains. Most scales are referred to Zuegelepis potanus Turner new genus and species. Associated with the thelodont scales are rare phosphatic fragments of questionable dermal “bone” and scales, possibly of heterostracan origin. Thelodont scales are also found in the Hendricks Formation at Fayette State Park, Michigan and in the subsurface Byron Formation (Burnt Bluff Group) in Schoolcraft County, Michigan.

Four specimens of a new cornute-grade stylophoran Ponticulocarpus robisoni new genus and species are described from the Spence Shale of northern Utah. Ponticulocarpus has wide and thin spinal and glossal processes interpreted as a mechanism for snowshoeing in a soft substrate. The presence of a posterior bar across the inferior posterior lobe, and two small bridges connecting the left adoral to M′2 on the superior face and connecting M1 to M3 on the inferior face are unique in cornute-grade stylophorans. The posterior bar may be homologous with the posterior marginals M′5 and M6 of other cornute-grade stylophorans, and an opening of the most posterior portion of the theca may have resulted in the development of the digital and glossal processes from marginals.

A crinoid and stelleroid fauna is described from the Famennian (Late Devonian) Broken Rib Member of the Dyer Formation of the White River Plateau, Colorado. The fauna postdates the Late Devonian extinction event. Six new crinoid species described, including the new genus Tarassocrinus, are: Strimplecrinus dyerensis, Catactocrinus? torus, Hypselocrinus? bisonensis, Gilmocrinus? albus, Eireocrinus? coloradoensis, and Tarassocrinus synchlydus. The cladid-dominated crinoid fauna is transitional between earlier Devonian and later Carboniferous faunas. It contains the first report of Cupressocrinites (a Famennian Lazarus taxon) and Eireocrinus? in North America and extends ranges of several Carboniferous genera into the Late Devonian. A preliminary revision of the Rhenocrinidae is recommended. The family Glossocrinidae is recognized, and the Cupressocrinitidae are transferred to the Gasterocomacea.

A new stelleroid genus and species, Pleiadeaster inceptus (Asteroidea; family unknown), and an ophiuroid, Ophiopolytretus aethus (Ophiuroidea; Lapworthuridae?) are named. In addition, Hudsonaster (Hudsonasteridae; Asteroidea) and two unassigned asteroids are present, and three further stelleroids cannot be assigned to the class level. Pleiadeaster and Hudsonaster are important because they suggest that the Late Devonian might have been a time of transition for asteroids. Ophiopolytretus aethus is an oegophiurid ophiuroid with distinctive respiratory? pores penetrating the disk plates.

Pliomerina Chugaeva, 1958, a characteristic element of the peri-Gondwanan Eokosovopeltis-Pliomerina Province, occurs in Llanvirn and Caradoc strata of the Argentine Precordillera. Three protaspid instars are present in the ontogeny of the Early Caradoc Pliomerina peripata new species. A species possibly representing Pliomerella is a rare element in Early Caradoc strata of the Las Aguaditas Formation. Prosopiscus is represented by a Llanvirn species with a first record of protaspid larvae for the enigmatic Family Prosopiscidae. Early growth stages support closest relations of prosopiscids to Phacopina. The presence of Pliomerina and Prosopiscus, along with the cheirurid Pateraspis, demonstrates a peri-Gondwanan influence on the Precordilleran fauna by the Llanvirn, and supports the proximity of the Precordillera terrane to the South American margin by that time.

New cheirurid trilobite species from the Las Aguaditas Formation in San Juan Province include the Llanvirn Macrogrammus rafi, and the Early Caradoc Ceraurinella zhoui, Nieszkowskia jakei, and N. yongyii. Precordilleran species, such as the Llanvirn Macrogrammus pengi new species from the Gualcamayo Formation, reinforce sinoparapilekiinid affinities for the poorly known Macrogrammus Whittard, 1966, although the monophyly of Sinoparapilekiini requires corroboration. The ontogeny of Ceraurinella zhoui confirms the presence of early protaspid stages for this genus (and Cheirurinae in general). Rare cheirurids include species of Heliomeroides, Pateraspis, and an additional acanthoparyphinid.

Silurian trilobites of the central United States belong to a series of temporally-successive associations which appeared abruptly, maintained taxonomic stasis for a time, and then disappeared abruptly. Their disappearance resulted from global perturbations of short-term duration and moderate magnitude, which caused substantial taxonomic replacement but no reorganization of major ecosystems. The most significant extinction and replacement in Silurian trilobite associations in the study area occurs near the Llandovery–Wenlock boundary. This turnover in trilobite associations appears to correspond to Jeppsson's Ireviken Event in his model of oceanic and climatic cyclicity. Major sea-level changes earlier in the Llandovery did not have a similar impact on trilobite associations.

A large ichthyosaur from the Los Molles Formation (Early Bajocian) of the Neuquén Basin, Northwestern Patagonia, Argentina, represents a new genus and species, Mollesaurus periallus. The holotype of M. periallus new species represents, along with the type of Chacaicosaurus cayi that was found at the same locality, the only diagnostic ichthyosaur specimens from the Aalenian-Bathonian interval.

Embedded thalli of Permian Ivanovia tebagaensis, a calcified, cyathiform, codiacean, Chlorophyta, were X-rayed with a medical CT (computed tomography) scanner. The two-dimensional digital X-ray image files were copied to floppy disks and transferred to an IBM-compatible personal computer. The images were cropped, and built into a data volume with a commercial three-dimensional software program. The data were color edited so that only the algae were visible. The data volume was then systematically manipulated to visualize some hitherto unknown details of the structure of the utricles, and of a vegetative propagule, a developing bud.

The Prout Dolomite of north-central Ohio lies disconformably above the lowest Givetian (upper Middle Devonian) Plum Brook Shale and below the lowest Famennian (upper Upper Devonian) Ohio Shale. A sample from its base yielded over 4,000 diverse conodont specimens. Included is Polygnathus ansatus Ziegler and Klapper, 1976, the index species for the Middle varcus Subzone, which is not reported from strata of this age in Ontario and Indiana, a fact that long caused their miscorrelation with the Lower varcus Subzone. Also present is P. rhenanus Klapper, Philip, and Jackson, 1970, considered to be also indicative of the Middle varcus Subzone in North America, and P. ovatinodosus Ziegler and Klapper, 1976. Lowest occurrences of the latter are in the middle part of this subzone; its presence indicates correlation with the lower Tully Limestone of New York, the basal unit of the Taghanic Series. The Prout and equivalent strata in the region therefore represent a long unrecognized continuous time-rock unit created by Johnson's (1970) Taghanic onlap. The collection includes a new species of Ancyrolepis, A. huntleyi; a new species of Polygnathus is left in open nomenclature, as are nine specimens assigned to Tortodus but of otherwise uncertain taxonomic status.

Givetian conodont correlation between North America and the Global Stratotype Section and Point established by the Subcommission on Devonian Stratigraphy (SDS) in Morocco is extremely problematical because of relatively erratic distribution (probably owing to limited ecologic adaptability) of P. ansatus and P. hemiansatus Bultynck, considered herein to be an early morphotype of P. ansatus. The base of the Givetian Stage has been defined by the SDS as coinciding with the lowest occurrence of P. hemiansatus. The only possible evidence for the SDS's hemiansatus Zone in North America involves reported occurrence of that morphotype in the uppermost Arkona Shale of Ontario, a position above the top of the Plum Brook Shale, which has been considered to be of Givetian age for decades. Also it appears that the interval between the Eifelian (lower Middle Devonian) kockelianus Zone and the hemiansatus Zone at the SDS's global-stratotype section in Morocco is of questionable age and probably too thin to represent continuous sedimentation. Adoption of a widely recognized faunal break at the base of strata deposited during the If T-R cycle of North America and Europe as the base of the Givetian could provide a sound alternative.

Over 600 elements of the Ordovician conodont index Eoplacognathus suecicus Bergström, 1971, were obtained from the Segerstad and Skärlöv Limestones at the Lunne section, which is the type locality of E. suecicus, and at the Kullstaberg section both in Jämtland, Sweden. Specimens of E. suecicus from different stratigraphic levels and representing different growth stages show obvious morphological differences. The stratigraphically early elements of E. suecicus are very similar to the stratigraphically late elements of Eoplacognathus pseudoplanus (Viira), being distinguished mainly by the appearance of the secondary postero-lateral denticle row in the stelliplanate element. Eoplacognathus suecicus apparently was derived from E. pseudoplanus, and probably evolved into Eoplacognathus lindstroemi (Hamar).

An isolated premaxillary tooth of a tyrannosaurid from the Lower Cretaceous section of the Tetori Group, Central Honshu, Japan, complements Siamotyrannus, which is based upon an incomplete postcranium for existence of tyrannosaurids in the Early Cretaceous of Asia. The occurrence of a tyrannosaurid tooth in the Japanese early Early Cretaceous further supports the possibility that tyrannosaurids originated during the Early Cretaceous in Asia and migrated to North America when the two continents were connected via a land bridge during the early Late Cretaceous. Thickening of the premaxillary teeth might have predated the increase in body size in tyrannosaurid evolution.

The change in depositional environments observed in the Cretaceous (Upper Campanian) strata in the region of Dinosaur Provincial Park, Alberta, from the proximal coastal plain deposits of the Oldman Formation to the lowland coastal plain deposits of the Dinosaur Park Formation, reveals an associated change in faunal composition. An assemblage collected from a microvertebrate site in the paralic deposits of the Lethbridge Coal Zone (uppermost Dinosaur Park Formation) reflects an increasing marine influence. Elasmobranch (sharks and rays) remains are the most abundant, both in terms of number of overall taxa and number of elements, and they are the best-preserved specimens. However, several brackish-water-tolerant osteichthyan taxa, and four reptile taxa (two marine and two terrestrial), were also recovered, although they exhibited evidence of extensive taphonomic reworking.

The elasmobranch fauna collected from the Dinosaur Park locality is uncommon for vertebrate microfossil assemblages in the Dinosaur Park Formation of Alberta and in equivalent beds in Montana. Seven of the 10 taxa collected from this site [Cretorectolobus olsoni Case, 1978; Eucrossorhinus microcuspidatus Case, 1978; Odontaspis aculeatus (Cappetta and Case, 1975); Archaeolamna kopingensis judithensis Siverson, 1992; Protoplatyrhina renae Case, 1978; Ischyrhiza mira Leidy, 1856; and Ptychotrygon blainensis Case, 1978] are recorded for the first time from the uppermost section of the Judith River Group in Alberta; Carcharias steineri (Case, 1987), represents the first occurrence within the upper Judith River Group from either Alberta or Montana.

Molostovskaja (1979, p. 54) described without illustrations the family Darwinuloididae Molostovskaja, 1979. The following year, Molostovskaja (1980, p. 33) described the family again as new [Darwinuloididae fam. nov.]. She included the genus Whipplella Holland, 1934, in the family and illustrated Darwinuloides svijazhicus (Sharapova 1948) (Molostovskaja, 1980, p. 28, figs. 5a, b, 8). Schneider (1948, p. 29, pl. 2, figs, 1a, b) originally described and illustrated this species as “Darwinula svijazhicus Sharapova n. mns.” Two years later, Molostovskaja (1982, p. 158) illustrated cross-sections of the adductor muscle attachment scar patterns in the families of the Darwinulacea Brady and Norman, 1889. Later Molostovskaja (1990, p. 166) erected the superfamily Darwinuloidacea Molostovskaja, 1979 to include Whipplella Holland, 1934, Vymella Kalis and Mischina in Mischina and Kalis, 1975, and questionably Pruvostina Scott and Summerson, 1943. In the same paper, she illustrated Whipplella sp. (pl. 72, figs. 6a, b) [from Sohn, 1977], Vymella dobrinini (Kashevarova, 1961) (pl. 72, figs. 7a-c), Darwinuloides sentjakensis (Sharapova in Schneider, 1948) (pl. 73, figs. 5, 6), and D. svijazhicus (Sharapova in Schneider, 1948) (pl. 74, figs. 14a, b).

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.

Trilobites from thrombolitic reefs in the Ore Hill Member of the Upper Cambrian Gatesburg Formation are assigned to (in ascending order) the Pseudosaratogia magna, Cliffia lataegenae, and Irvingella major Subzones of the Elvinia Zone. These reef faunas contrast markedly with those from coeval off-reef grainstones (tempestites), representing separate biofacies rather than biostratinomic variants. Associated lithologies suggest that the fauna of the P. magna Subzone at the base of the member comprises a biofacies associated with shallower microbial reef environments than those occupied by faunas in the overlying C. lataegenae Subzone. Reefs in the C. lataegenae Subzone yield a fauna dominated by Buttsia drabensis, extending the documented range of catillicephalid abundance in microbial reef biofacies downward into the highest strata of the Steptoean Stage. This reef fauna also includes several new taxa, including Cheilocephalus quadratus new species (described herein), an atypical species of Cheilocephalus with catillicephalid-like cranidial features. The fauna in off-reef tempestites low in the C. lataegenae Subzone contains the genera that characterize the Xenocheilus–Kindbladia Biofacies, expanding the known environmental and geographic range of that biofacies. Sulcocephalus, typically a minor component of faunas in the I. major Subzone, dominates the fauna in reefs within this subzone such that a distinct Sulcocephalus Biofacies can be recognized immediately above the extinction horizon that defines the base of the Sunwaptan Stage.