Problematic sclerites are common in Cambrian rocks around the world, but much less so in those of the Ordovician. Eurytholia prattensis new genus and species and E. elibata new species, described herein, are rare but widely distributed faunal elements in a narrow stratigraphical interval (Pygodus serra and P. anserinus conodont biozones) within Ordovician beds in an area bordering Iapetus (South Wales, UK; Alabama, USA; Dalarna, Sweden; and North Estonia). Specimens are minute plates (usually less than 1 mm wide), transversely ovoid, and hollow. They are not closely comparable with any previously described fossils. Eurytholia plates are interpreted as dorsal dermal sclerites from an animal of uncertain affinities. The scleritome is provisionally reconstructed as ovoid in form, with sclerites arranged in sub-longitudinal rows.

Through a review of older type collections and identifications of undescribed collections, using a broad species definition, the Devonian succession is divided into 10 assemblages. The names of many species are revised. With the exception of the Pragian, all stages of the system are represented by one or more assemblages. The ranges of important taxa are plotted and shown to be relatively short and diagnostic of the 10 intervals. In the absence of conodonts in the reef facies, stromatoporoids offer a supplementary method of correlation. Many species occurring in Canada can be recognized in the stromatoporoid faunas of the former Soviet Union, China, Europe, and Australia.

Heliophyllum halli contains highly variable, mostly solitary rugose corals. Specimens reported here come from shaly beds of the Middle Devonian Hamilton Group in New York State. Early recognition of morphotype variation led James Hall to establish numerous species in the H. halli group that were later interpreted by John Wells in terms of varying life history. Life on unstable and/or soft substrates was facilitated for these corals by talons, root-like structures that allowed larval settling and post-larval development on hard particles such as echinoderm or shell debris. Variation in subsequent growth history is reflected in corallum shape and change in diameter. Straight growth axes reflect partial burial accompanied by vertical growth, while growth axis curvature resulted from unequal settling into substrate or alternatively, life at the surface of substrate, with sharp bends (geniculations) reflecting major changes in growth orientation. Decrease in diameter resulted from environmental stress, with greatest effects on the peripheral portion of the calice. Other major reactions to increased burial rate (through sinking or increased sedimentation) are epithecal secretion to form an outer wall for isolation of itself from surrounding sediment or decrease in polyp size as shown by terminal shrinking of the corallum diameter, at times nearly to zero. Yonge's (1940) summary of observations on living coral polyps suggests that the living H. halli was nonzooxanthellate, with an efficient system of feeding that utilized its multitude of tentacles without the help of cilia, which thus were able to generate currents to promote efficient sediment cleansing. Sediment shedding would also have been aided by polypal distension (swelling) above a reflexed calical margin.

The Early Carnian (Upper Triassic) phaceloid coral originally described by Volz (1896) as Hexastraea fritschi, type species of Quenstedtiphyllia Melnikova, 1975, reproduced asexually by “Taschenknospung” (pocket-budding), a process documented herein for the first time. This type of budding is recognized only in the Amphiastraeidae, a family thus far recorded only from Jurassic-Cretaceous strata. Similar to amphiastraeids, Quenstedtiphyllia fritschi (Volz, 1896) has separate septal calcification centers and a mid-septal zone built of serially arranged trabeculae. The most important discriminating characters of the new amphiastraeid subfamily Quenstedtiphylliinae are one-zonalendotheca and radial symmetry of the corallite in the adult stage (in contrast to two-zonal and bilateral symmetry in the adult stage in Amphiastraeinae). Quenstedtiphyllia fritschi shares several primitive skeletal characters (plesiomorphies) with representatives of Triassic Zardinophyllidae and, possibly, Paleozoic plerophylline rugosans: e.g., thick epithecal wall and strongly bilateral early blastogenetic stages with the earliest corallite having one axial initial septum. To interpret the phylogenetic status of amphiastraeid corals, we performed two analyses using plerophylline rugosans and the solitary scleractinian Protoheterastraea, respectively, as the outgroups. The resulting phylogenetic hypotheses support grouping the Zardinophyllidae with the Amphiastraeidae in the clade Pachythecaliina (synapomorphy: presence of pachytheca). Taschenknospung is considered an autapomorphy for the Amphiastraeidae. This study is the first attempt to analyze the relationships of the Triassic corals cladistically.

Two new genera and ten new species of shallow-marine, warm-water gastropods are reported from several Upper Cretaceous formations found between British Columbia and southern California. The buccinid Zaglenum new genus is represented by two new species and the turbinellid Fimbrivasum new genus is represented by three new species. The nododelphinulid Trochacanthus pacificus new species is the first record of this genus in the Western Hemisphere, and the procerthiid Nudivagus? califus new species could be the first record of this genus on the Pacific slope of North America. The xenophorid Xenophora (Endoptygma) hermax new species is only the second known Cretaceous species of this genus on the Pacific slope of North America, and this species establishes that Endoptygma Gabb, 1877, is a valid taxon. The neritid Otostoma sharonae new species is only the fourth known Cretaceous species of this genus on the Pacific slope of North America. The ringiculid Ringicula? (Ringiculopsis?) hesperiae new species is the first Campanian record of this genus on the Pacific slope of North America and the first recognition of this subgenus in this area.

A diverse fauna of numerous, well-preserved polyplacophorans are present in the Mississippian (Osagean) Gilmore City Formation, Humboldt Member at Humboldt, Iowa. Specimens were collected from oolitic and skeletal packstones. New taxa include Gryphochiton demissus new species, Euleptochiton ellipticus new species Platychiton gerki new genus and species, Angulochiton humboldtensis new genus and species, and Systenochiton triangulus new genus and species.

The functional morphology and autecology of leperditicopid arthropods (Ordovician-uppermost Devonian) are analyzed in the light of well-preserved specimens from the Devonian of China and detailed comparisons with recent ostracodes. Leperditicopids were large, bivalved arthropods (adults ranging from 5 to about 50 mm in length) typically with an asymmetric carapace (strong ventral overlap), a complex muscular system (powerful adductors, extrinsic muscles, tendinous structures) whose insertions are preserved as scars on the inner surface of the exoskeleton and steinkerns, and an extensive radiating network of integumental sinuses probably involved in gaseous and ionic exchanges (oxygen uptake and transport, osmoregulation). The conspicuous chevron scars adjacent to the adductor scars are interpreted as the anchoring spots of mandibular tendinous structures possibly involved in the opening mechanism of the valves. The ultrastructure of the carapace is comparable to that of thick-shelled recent myodocopid ostracodes. A review of leperditicopid occurences (depositional environment, associated faunas and floras) shows that the group preferentially occupied very shallow marginal habitats (tidal flats, reef-flats, lagoons, embayments, or estuarian complexes) that were subjected to environmental stress (salinity, temperature, moisture). This ecological range implies specific adaptations (osmoregulation, resistance to desiccation) supported by morphological evidence (e.g., circulatory system, carapace closing system, thick shell). Most leperditicopids had epibenthic lifestyles and were probably detritus feeders. They may have been adapted (powerful mandibles) to scrape food on algal/microbial mats. Their typical pattern of occurrence (monospecificity, large numerical abundance) displays some of the characteristics of opportunistic populations (e.g., recent ostracodes, branchiopods) living in variable environments. Morphological similarities with Ostracoda are important (e.g., muscular and tendinous features, circulatory system, valve overlap, carapace ultrastructure) but taxonomic relationships with that group remain inconclusive because of the lack of evidence from soft parts.

Phylogenetic analysis was used to evaluate evolutionary relationships within the Cambrian suborder Olenellina Walcott, 1890; special emphasis was placed on those taxa outside of the Olenelloidea. Fifty-seven exoskeletal characters were coded for 24 taxa within the Olenellina and two outgroups referable to the “fallotaspidoid” grade. The Olenelloidea, along with the genus Gabriellus Fritz, 1992, are the sister group of the Judomioidea Repina, 1979. The “Nevadioidea” Hupé, 1953 are a paraphyletic grade group. Four new genera are recognized, Plesionevadia, Cambroinyoella, Callavalonia, and Sdzuyomia, and three new species are described, Nevadia fritzi, Cirquella nelsoni, and Cambroinyoella wallacei. Phylogenetic parsimony analysis is also used to make predictions about the ancestral morphology of the Olenellina. This morphology most resembles the morphology found in Plesionevadia and Pseudojudomia Egorova in Goryanskii and Egorova, 1964.

Although Middle Cambrian trilobites of the Braintree Member in eastern Massachusetts were among the first published on in North America, re-examination of this fauna has led to wholesale taxonomic and biostratigraphic re-evaluation. This low diversity fauna now includes at least seven species, with the first report of agnostoids (three poorly preserved taxa) and the ellipsocephalid Kingaspis avalonensis new species. Paradoxides (Acadoparadoxides) harlani Green emend., a senior synonym of P. (A.) haywardi Raymond, allows correlation into the lowest Middle Cambrian elsewhere in Avalon. However, all the polymeroid species are endemic, and this precludes a highly resolved correlation into other Cambrian paleocontinents. A breakdown of provincial barriers in the late Early Cambrian as western Gondwana passed from equatorial to the higher south latitudes of Avalon led to faunal exchanges between these continents. Paradoxides (Acadoparadoxides) and Kingaspis of the Braintree fauna are shared with western Gondwana, while Braintreella and “Agraulos” quadrangularis are closest to genera known from the Spanish, Moroccan, and Perunican (Bohemian) margins of Gondwana.

A recently discovered series of hardground surfaces in the lower Salem Limestone (Meramecian, Mississippian) and upper Muldraugh Member of the Borden Formation (upper Osagean to lower Meramecian, Mississippian), in Hardin County, Kentucky is colonized by a hard substrate community that includes three species of pyrgate edrioasteroids. Torquerisediscus kypsi n. gen. and n. sp. differs from other edrioasteroids by bearing a cyclic pattern of twelve ambulacral cover plates and meandering distal ambulacra. Ulrichidiscus spinosus n. sp. differs from other species of Ulrichidiscus by the presence of large spines on the ambulacral cover plates, anal pyramid plates, and hydropore orals. Two small specimens are assigned tentatively to Ulrichidiscus aff. pulaskiensis.

Edrioasteroid populations occurring on several surfaces show marked differences in size frequency distribution. Three of the surfaces only have large individuals of Torquerisediscus kypsi whereas a fourth surface is colonized by only juvenile specimens of T. kypsi as well as both species of Ulrichidiscus suggesting subtle differences in environment and duration of surface colonization prior to burial. Furthermore, taphonomic pathways differ among these four surfaces with some containing only disrupted individuals and others containing only fully articulated individuals suggesting either differences in burial depth, or some differences in decomposition of edrioasteroid carcasses prior to final burial.

The Všeradice section was trenched and continuously sampled for graptolites from the base of the post-extinction upper Homerian strata to low in the Ludlow. The upper Homerian is divisible into three biozones, a lower parvus–nassa Biozone, a middle praedeubeli–deubeli Biozone, and an upper ludensis–gerhardi Biozone, the last named being succeeded by graptolites of the lowest Ludlow nilssoni Biozone. The graptolite diversity of nine species in the upper part of the parvus–nassa Biozone is the highest in the world. Five monograptid species, Pristiograptus parvus Ulst, 1974, P. dubius (Suess, 1851), Colonograptus deubeli (Jaeger, 1959), Colonograptus gerhardi (Kühne, 1955), and Colonograptus praedeubeli (Jaeger, 1990) are described from the upper Homerian. Twelve species of retiolitids, Gothograptus nassa (Holm, 1890), Neogothograptus cf. balticus (Eisenack, 1951), Spinograptus spinosus (Wood, 1900), Spinograptus clathrospinosus (Eisenack, 1951), Spinograptus munchi (Eisenack, 1951), Spinograptus reticulolawsoni (Kozłowska-Dawidziuk, 1997) Spinograptus? cf. nevadensis (Berry and Murphy, 1975), Spinograptus? sp. A and Spinograptus? sp. B, Plectograptus macilentus (Törnquist, 1887), and Plectograptus? karlsteinensis new species and Plectograptus? ovatus new species, are described and illustrated from upper Homerian and lowest Ludlow strata. The two new species occur in the upper parvus–nassa and lowest praedeubeli–deubeli, and ludensis–gerhardi biozones, respectively. Two morphs of Gothograptus nassa, a narrow (more typical) form, and a wide form, are recognized. While overlapping in their overall ranges, their occurrences in any particular small interval are sometimes mutually exclusive, suggesting ecological control.

An unusually well-preserved fauna of isolated monograptid graptolites has been recovered from the Sakmara Formation, in the Orenburg District of the South Urals of Russia. Seven different taxa belonging to three genera can be distinguished in these collections, including four new species, Pribylograptus orskensis n. sp., Monoclimacis? galeritus n. sp., Monoclimacis? orenburgensis n. sp., and Monoclimacis? oscitatus n. sp. Study of these new species using infrared video microscopy reveals two features never previously identified in monograptid graptolites on the three species of Monoclimacis?: thecal hoods constructed from both apertural and genicular fuselli; and, a resorption porus that shows some outward inflation or bulging as well as slight fusellar deflection. These two features may both represent stages of morphologic transition to the more “advanced” primary porus and apertural hoods and hooks seen in later monograptids. Phylogenetic analysis of these and some other Rhuddanian taxa suggests that species with “monoclimacid”” thecae arose once in the Rhuddanian from a Huttagraptus ancestor and these species later gave rise to the various groups of biform and uniform monograptids with apertural-hooded and hooked thecae. Those biform taxa with “monoclimacid” or hooked proximal thecae and lappeted (“pribylograptid”) distal thecae appear to have arisen from within this group independently of the lineage leading to Pribylograptus sensu stricto.

Based on specimens from Australia and Iran, five species of rhipidognathid conodonts, Appalachignathus delicatulus Bergström, Carnes, Ethington, Votaw, and Wigley, 1974, Bergstroemognathus extensus (Graves and Ellison, 1941), B. hubeiensis An (MS) in An, Chen, and Li, 1981, B. kirki Stait and Druce, 1993, and Rhipidognathus? yichangensis (Ni, 1981), are described and revised in terms of multielement morphology. All three genera comprising the Rhipidognathidae are interpreted as having a septimembrate apparatus, partially confirmed by bedding plane assemblages of B. extensus from Victoria. Occurrence of A. delicatulus in allochthonous limestones (about the Middle-Upper Ordovician boundary) of central New South Wales is the first record of the species outside North America. Recognition of Rhipidognathus? yichangensis in Early Ordovician strata of the Canning Basin, reinforces biogeographic affinities of Australia and South China. The three described species of Bergstroemognathus are mainly restricted to late Early Ordovician strata. Bergstroemognathus extensus is widely distributed in North America, western Argentina (Precordillera), China, and Australia. Bergstroemognathus hubeiensis, described from east-central Iran, has been previously recorded only from China, while the slightly younger B. kirki seems endemic to central and northern Australia, where it was restricted to shallow, warm water environments. In contrast, B. extensus and B. hubeiensis inhabited a spectrum of water depths from shallow to deep.

One of the southernmost North American late Campanian microvertebrate assemblages was collected from the upper Aguja Formation, Big Bend National Park, Texas. The dinosaurs provide additional evidence that distinct southern and northern terrestrial vertebrate provinces occurred contemporaneously during this time due to latitudinal differences in temperature and rainfall. Southern areas, such as west Texas, were warm dry, with non-seasonal climates, and with open-canopy woodlands; they appear to be less fossil-rich and less diverse than northern areas. Nine dinosaurs are present, based on isolated teeth: pachycephalosaurid; hadrosaurid; ceratopsian; tyrannosaurid; Saurornitholestes cf. langstoni (Sues, 1978); Richardoestesia cf. gilmorei (Currie et al., 1990); a new species of Richardoestesia, which is named here; and a undetermined theropod unlike any previously described. Previous reports of Troodon sp. from the Talley Mt. and Terlingua microsites are mistaken; they are a pachycephalosaurid. Many of the dinosaur teeth are small, and are probably from juveniles or younger individuals, evidence that dinosaurs nested in the area. Paleoecologically, the upper Aguja was probably more similar to the lower and more inland faunas of the Scollard Formation (~66 Ma) of Alberta than to contemporaneous northern faunas: both had drier, open environments and lower dinosaur abundance. This connection between climate and dinosaur abundance suggests that climatic factors were important in the Late Cretaceous dinosaur extinctions.

Abundant examples of exoskeletal abnormalities have been known in various trilobites since Portlock's (1843) first report on a teratological pygidium of Phillipsia ornata (cf. Babcock, 2000). Owen (1985) and Babcock (1993) recognized three types of trilobite malformations: healed injuries, teratological conditions, and pathological conditions. It is not always easy, however, to distinguish between the various types of malformations, especially in case of teratological or pathological conditions. In general, healed injuries are considered to have resulted from trauma during molting (Walcott, 1883; Whittington, 1956; Henningsmoen, 1975; Snajdr, 1981; Owen, 1983; Ramsköld, 1984) or wounds by predatory attack (Ludvigsen, 1977; Rudkin, 1979; Ŝnajdr, 1979, 1981; Owen, 1985; Conway Morris and Jenkins, 1985; Babcock, 1993; Pratt, 1998). Many healed injuries are indicated by broken spine stumps, indented and cicatrized edges of exoskeletons, and callused or regenerated exoskeleton around the broken surface (Ŝnajdr, 1981; Owen, 1983; Babcock, 1993). Teratological conditions are represented primarily by the irregular development of glabellar lobes, cephalic borders, and pygidial border spines, and anomalous number of segments on the thorax and pygidium. For example, Owen (1980) described a teratological cranidium of Calyptaulax norvegicus with two additional lateral glabellar lobes between the l p and 2p lobes. On the other hand, pathological conditions are marked by gall-like swellings and vermiform borings on exoskeletons that are thought to have been caused by diseases or parasitic infestation (Lochman, 1941; Ŝnajdr, 1978; Conway Morris, 1981; Owen, 1985).