New specimens of the arthropod Pectocaris Hou, 1999 have yielded important new information. The entire body of Pectocaris spatiosa Hou, 1999 is known. Odaraia? eurypetala Hou and Sun, 1988 is transferred to Pectocaris. In addition to the finlike lateral flukes, setal imprints and new specimen indicate a median fluke as in the Burgess Shale Odaraia. The cephalic region bears stalked eyes and the crustacean characteristics first and second antennae and mandibles. The mandibles are succeeded by about 53 pairs of branchiopod-type appendages, each corresponding to a head or body segment. Branchiopod characters include endites with setae turned backwards, the elongation of the telson, and its fluke-shaped rami. Pectocaris has a fairly basal position in the phylogenetic tree of the extant crustaceans and probably belongs to the branchiopod crustaceans. It is the first arthropod with definite crustacean characteristics described from strata from below the Upper Cambrian.

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.

A review of all known species of the scutelluine trilobite Paralejurus corroborates its distinction from contemporaneous representatives of the subfamily. The overall morphology together with observed habitat conditions favor the view of its having had a semiendobenthic life habit analogous to that of many earlier illaenids. Particular features that are shared with the Silurian Rhaxeros, such as the pronounced convexity of the exoskeleton and the wide axis, are considered as homeomorphies related to a burrowing lifestyle rather than the expression of phyletic relationships. The data set based on conodont biostratigraphy reveals earliest occurrences of Paralejurus in the Pragian and the disappearance of last representatives at the base of the Middle Devonian. In the lower Early Devonian Paralejurus was restricted to the North Gondwana margin and related microplates. Later and in consequence of geodynamic plate movements that led to the reduction of oceanic barriers, the Paralejurus dormitzeri group succeeded in spreading to the epicontinental margin of Laurussia in Late Emsian times. New material from Southern Morocco, including Paralejurus spatuliformis n. sp. and Paralejurus tenuistriatus n. sp., and the first representative of the genus from Spain, Paralejurus carlsi n. sp., are described. Paralejurus dormitzeri rehamnanus Alberti, 1970 is considered an independent species emphasized by the discovery of complete exoskeletons.

The Shanglun Formation at the Shanglun locality contains a sinoleperditiine fauna of five species of which two are new [Sinoleperditia (Sinoleperditia) shanglunensis and Paramoelleritia (Paraleperditia) wangchengyuani] and one is left in open nomenclature because of inadequate materials. In this fauna, the ratio of the vertical height of the trailing chevron muscle scar to that of the adductor muscle scar (th:ah ratio) ranges from 0.85 to 0.95 with a mean value of 0.90. On the basis of the sinoleperditiines and a beyrichiid ostracode, the upper part of the Shanglun Formation is correlated with the middle-to-late early Emsian Moding Formation. The sinoleperditiines and microfacies analysis indicates that the sediments bearing the fauna were deposited in a low energy restricted carbonate platform environment.

A new small twiglike anthaspidellid sponge, Virgaspongiella ramosa new genus and species, and an incrusting lithistid sponge have been recovered from silicified residues of etched limestone blocks from the Middle Permian Franson Member of the Park City Formation in western Wyoming. Virgaspongiella n. gen. has a skeleton of upwardly and outwardly divergent trabs formed of merged tips of runglike dendroclone spicules in ladderlike series. One to a few oxeas function as coring spicules in the trabs and project as fine spines from the dermal surface, and other monaxial spicules project from pores of the canals.

The incrusting sponge, Incrustatospongia superficiala new genus and species, forms a distinct, thin, uniform lithistid skeletal layer, composed largely of X-shaped dendroclones, incrusted on both the inner and outer surfaces of productoid brachiopod valves. Separated monaxial spicules locally protrude from the sponge's dermal surface apparently as spinose defensive elements.

The oldest known thrips, order Thysanoptera, are described from the Late Triassic of Virginia and Kazakhstan: Triassothrips virginicus Grimaldi and Fraser, new genus and species (Cow Branch Formation: Carnian), and Kazachothrips triassicus Shmakov, new genus and species (Tologoy Formation: Carnian-Norian). Prior to this the oldest definitive thysanopterans were from the Late Jurassic of Kazakhstan (Kimmeridgian), some 80 My younger. Well-preserved, relatively complete, wing venation indicates the Triassic thrips are phylogenetically the basalmost thysanopterans, and their venation even allows identification and homologizing the highly reduced veins in Recent thrips. Another basal thrips is described from mid-Cretaceous (Turonian) amber of New Jersey, Cretothrips antiquus Grimaldi, new genus and species, which is similar to several Recent genera of Aeolothripidae. A phylogenetic hypothesis of basal relationships in Thysanoptera based on wing venation supports a basal relationship for Aeolothripidae and derived position for Phlaeothripidae among Recent families.

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.

More than 500 specimens of embryonic shells of orthocerid nautiloids from the Imo Formation were investigated. Although the material is recrystallized, the external and internal features of the early growth stages are exceptionally well preserved. The material comprises eight species of Pseudorthoceratidae: Pseudorthoceras knoxense (McChesney, 1860); Ristedtoceras teriliratum n. sp.; Mooreoceras imoense n. sp.; Mooreoceras striatulum n. sp.; Reticycloceras peytonense Gordon, 1965; Dolorthoceras tenuifilosum Gordon, 1965; Mitorthoceras girtyi Gordon, 1965; and Euloxoceras angustinus Gordon, 1965. A new genus, Ristedtoceras, is erected and the genus Pseudorthoceras Girty, 1911 is emended.

The analysis indicates that the morphologic diversity of the early growth stages of the shells of these species are much more diverse than expected. The different species vary strongly in the embryonic shell size, cicatrix position and shape, numbers of septa in the embryonic shell at the time of hatching, embryonic shell ornamentation, and the outline of the first segment of the siphuncle and its position in cross section. This study shows that the shape and position of the cicatrix is a morphologic feature that has been under utilized in previous investigations. The high morphologic variance of the embryonic shells in these Imo orthocerids requires a revision of our understanding of the Pseudorthoceratidae. In addition, the implication of this analysis strongly supports using the morphology of the embryonic shell, and especially the cicatrix, in all future orthocerid systematic and phylogenetic analyses because it is proving to be an important set of characters in detecting homeomorphic evolutionary relationships that are not discernable in mature specimens.

Halkieriids are part of a distinctive Early Cambrian fauna, the “Tommotian fauna” sensu Sepkoski (1992), that is preserved mostly as phosphatic and secondarily phosphatized skeletal elements. The distinctiveness of the Tommotian fauna is ascribed, in part, to its preferential elimination during the end-Early Cambrian mass extinction event (the “Botomian extinction”). Newly discovered halkieriids in phosphatic limestones of the Middle Cambrian (Ptychagnostus gibbus Zone) Monastery Creek Formation, Georgina Basin, Australia, now indicate that this group not only survived the end-Early Cambrian extinction, but was at least locally abundant thereafter. Most of the Georgina halkieriid sclerites can be accommodated within a single species, Australohalkieria superstes new genus and species, described and partly reconstructed here. Remaining sclerites probably represent two additional but rare halkieriid species. Additional newly discovered sclerites may have affinities with the sachitids, another problematic “Tommotian” taxon related to the halkieriids. Rare wiwaxiid sclerites extend the taphonomic and geographic distribution of this clade. The Monastery Creek Formation provides a valuable window on Middle Cambrian life, both because it provides information that is distinct from but complementary to other, similarly aged windows (e.g., the Burgess Shale) and because it represents a taphonomic window similar to those that preserve Early Cambrian small shelly problematica. A decline during the Cambrian in conditions necessary for the early diagenetic phosphatization of shallow-shelf and platform limestones may have effectively closed this taphonomic window, potentially biasing apparent patterns of diversity change through the period.

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.

Application of new preparation techniques for cleaning and study of fossil crabs to Dromiopsis rugosa (Schlotheim, 1820), from the late middle Danian limestone in the Fakse quarry, Denmark, has revealed remarkable detail of the carapace surface and epibionts infesting inner and outer surfaces of the carapace. Epibionts, identified as clionid sponges, scleractinian corals, cheilostome and ctenostome bryozoans, serpulid worms, and brachiopods, are interpreted as having attached to molted carapaces after the molted carapace had been released.

All known post-Paleozoic asteroids belong to the crown group, and no crown-group asteroid is known from the Paleozoic. A scanty fossil record provides limited data on morphology of both Paleozoic stem-group sister lineages and on the Triassic crown group diversification. Timing of events is weakly constrained. Interpretations based on this meager record are tentative.

Within limitations of the record, recent work suggests that skeletal arrangement of the ventral surface offers apomorphies of crown-group diversification. Enlarged disk size is common in the crown group. Large disks are constructed in part by addition of many ventral and ventral-lateral so-called “actinal” ossicles. Actinals in the crown group are comparatively uniform in size, shape, and arrangement within each species. Actinal alignment is of one of two patterns, parallel to adambulacrals or parallel to marginals. Actinals in the crown group are tentatively considered to be an apomorphy of the crown group, although the incomplete fossil record leads to uncertainty.

Enlarged disks are found in some Paleozoic (stem-group) asteroids. Axillary ossicles, marginal series extending onto ventral interbrachia, and enlarged disk adambulacrals are modes of disk size increase known only from Paleozoic asteroids. Actinal ossicles are found in a few stem-group species but arrangements are unlike those of the crown group.

Certain Carboniferous and Permian genera share aspects of ambulacral column construction with the crown group, but lack actinal apomorphies. Actinal arrangement is available for two of the three known Triassic genera. In certain ways, patterns are intermediate between stem-group and Jurassic and younger crown-group asteroids.

Carniaster orchardi n. gen. and sp. (Echinodermata: Asteroidea) is only the fourth Triassic asteroid known from material complete enough to warrant a generic name. Data indicating familial and ordinal positions are not available. All four Triassic genera belong to the exclusively post-Paleozoic crown group. Carniaster does not appear to differ significantly from other described Triassic genera, and it probably represents a broadly basal lineage within the crown group diversification. Available morphological data suggest no ecologic parameters that would be unusual among living asteroids. Carniaster is the first complete Triassic asteroid known from beyond Europe.

Based on 137 specimens examined, the new species Commutia exoleta is characterized by a small, slightly scolecoid shape with 21 septa at a mean maximum corallite diameter of 6 mm (range 3 to 10.5 mm); a persistent inner wall, which encloses an aulos with a mean maximum diameter of 1.2 mm, formed during an early ontogenetic stage when the axial ends of the cardinal, alar and counter-lateral septa fused; short counter septa are lacking in the earliest stage of development.

Corallites are highly variable. Characters exhibiting a wide range of variation are: size and shape of corallites, number of septa, diameter of aulos and the timing of its appearance, number of septa connected to the inner wall, and the septal arrangement in each growth quadrant. Combinations of these variable characters result in corallites that are each uniquely different. Variations of those characters are partly due to stressed environments, such as unstable, muddy substrates resulting in corallite rejuvenescence and redirection.

Epibionts on both living and fossil decapod crustaceans may serve as valuable proxies for paleoecological factors such as behavior and environment. Prevalence of epibionts, as observed primarily on the carapaces of fossil brachyurous decapod crustaceans, appears to be less than observed on living crabs, based upon observations in the literature, and from the study of a limited preserved biological and fossil collection. Among these factors, the three most important are that many extant epibionts do not possess skeletal structures and, therefore, are unlikely to be preserved; the epicuticle upon which epibionts attach to living brachyurans is lightly calcified and tends to be lost readily as a result of taphonomic processes; and the most common mode of preservation of fossil brachyurans is in concretions which tend to break open and leave a layer of cuticle on the counterpart, thus obscuring the potential surface of attachment of epibionts. Other factors such as the life habits of the crab, whether burrowing, burying, or remaining above the substrate; lifestyle, whether benthic or pelagic; and duration of the intermolt phase of the organism also play important roles in potential prevalence of epibionts. Careful preparation of part and counterpart remains of brachyurans as well as reference to the occurrence of epibionts in systematic studies will enhance knowledge of the host and epibiont.

Numidiaphyllum is one of the Paleozoic scleractiniamorphs. The genus is characterized by a poorly integrated, uniserial fasciculate form with an epithecate wall and simple morphological traits. Parent corallites are divided into several daughter corallites using one mode of division among several theoretically possible alternatives. Bipartite increase is most common, followed by hexapartite and then tripartite increase. Daughter corallites possess relatively large diameters from the beginning, along with a robust colonial pattern. This parricidal increase caused the morphologies of both parent and daughter corallites to be greatly altered and to show high morphological variability. For ecological and structural reasons, co-occurring daughter corallites generally are equal or subequal in size. Daughter corallites initially show a bilateral symmetry in both outline and septal arrangement during the course of hystero-ontogeny. However, this symmetry results only from structural necessity and is transitory. It is not homologous with the bilaterality of body plans characteristic of anthozoan groups. The morphological simplicity, related parricidal reproduction, and resulting poorly integrated growth form as seen in Numidiaphyllum, all suggest conservative features that could have resulted from phylogenetic antiquity within the scleractiniamorph body plan. Those generalized features are not themselves related to immediate phylogenetic relationships with any simply constructed rugosan group, nor would they have been due to surrounding, stressful ecologic conditions. They may have been phylogenetic-specific.

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.

The upper part of cores of the Onakawana B Drillhole in the Moose River Basin in northern Ontario includes the upper part of the upper member of the Williams Island Formation (22.5 m, 16 samples), and the entire overlying Long Rapids Formation (75.1 m, 49 samples). The sequence of conodonts from the drillhole was analyzed by graphic correlation as well as conventional zonation.

The upper carbonate member of the Williams Island Formation correlates with lower Frasnian zones 2 to 5. Below this, mixed Frasnian and Famennian conodont faunas occur partly in a brecciated interval within the member and represent stratigraphic leak below the Frasnian. The lower member of the Long Rapids Formation correlates in its lowest part with Zone 5, followed by a hiatus of zones 6 to 8. This is succeeded by zones 9 and 10. Zone 11 is missing, followed by an interval that correlates with upper Frasnian zones 12 and 13 to within the lower Famennian Middle triangularis Zone. The Frasnian-Famennian boundary occurs within a narrow interval in the lower member. The Upper triangularis Zone and perhaps part of the Middle triangularis Zone are missing.

The middle member of the Long Rapids Formation correlates with the Lower to Uppermost crepida zones. A sequence from high in the rhomboidea Zone to within the Lower marginifera to perhaps slightly into the Upper marginifera Zone occurs in the upper member of the formation.

Sixteen species are described, of which seven are new: Palmatolepis angularis, P. angusta, P. mystica, P. nodosa, P. parva, Palmatolepis n. sp. A, and Mehlina? unica. Two species that affect definition and identification of the Frasnian-Famennian boundary, P. triangularis and P. ultima (=P. praetriangularis), are revised.

Previously undescribed trilobites associated with microbial patch reefs have been recovered from the Upper Cambrian (upper Steptoean Stage) Ore Hill Limestone Member of the Gatesburg Formation in south-central Pennsylvania. Reefs in the Imler Quarry and Drab-Beaverton measured sections yielded low-diversity assemblages of trilobites that we assign to the uppermost Cliffia lataegenae Subzone of the Elvinia Zone. The faunas are dominated by the catillicephalid Buttsia drabensis Wilson, 1951, and include several new taxa that are not known from coeval off-reef facies. Fine-scale correlation between the two sections reveals that the reefs in the Drab-Beavertown section are slightly younger than those at Imler Quarry and represent the youngest Steptoean fauna described from the Appalachian region.

New taxa include Imlerella n. gen. (type species Imlerella praecipita n. sp.), Stittaspis n. gen. (type species Stittaspis loria n. sp.), and Dellea rogersi n. sp. Stigmacephalus? distorta Wilson, 1951, is reassigned to Stittaspis and is restricted to the type. Additional material of Buttsia drabensis illustrates features not discernible in previous treatments of this variable species.

New aplodontid material recovered from Hepburn's Mesa, Montana, stimulated reexamination of Ansomys, a genus of aplodontid previously known only from Asia. A cladistic analysis of the known species of Ansomys, as well as new material from Hepburn's Mesa and a few other morphologically similar species, prompted reconstruction of the biogeographic history of the genus. One new species, A. hepburnensis, from the Barstovian of Montana, is described, and two other species, A. nexodens and A. descendens, are placed in Ansomys rather than in Pseudallomys and Plesispermophilus, respectively. Addition of these three species to Ansomys extends its distribution throughout the Holarctic in the mid-Miocene. Stratigraphic ranges combined with phylogenetic relationships between species suggest this wide distribution as early as the late Oligocene, which is unique among aplodontid genera. The distribution, the rarity, the unusually small size, and the complex cusp morphology of Ansomys suggest a very specialized ecology for members of this clade.