The ostracode genus Poseidonamicus has been widespread and abundant in deep-sea sediments since the Eocene. Despite its prominent role in a number of evolutionary studies, species identification in this genus is often difficult and phylogenetic relationships among its species are not well understood. Here I present the findings from a comprehensive study of this genus with the purpose of discovering novel phylogenetic characters and clarifying species relationships. I briefly describe the adult carapace and trace some of the major morphological changes that occur over the last several instars. I focus particular attention on the arrangement of fossae in the reticulate mesh; these features have been shown in other ostracodes to correspond to underlying epidermal cells. I describe the development of fossae in the region posterior to the adductor muscle scars, and hypothesize a sequence of specific cell divisions to account for the addition of fossae over ontogeny.

Phylogenetic characters were derived from many different types of characters, including aspects of carapace shape, the presence and location of pores, characteristics of specific ridges and spines, and the relative position of homologous fossae in the reticulum. A parsimony analysis of 42 characters and 40 operational taxonomic units (36 ingroup and four outgroup) resulted in a set of optimal trees whose strict consensus is relatively well resolved, well supported, and generally consistent with the order in which taxa appear in the fossil record. the monophyly of Poseidonamicus is supported, as is the monophyly of all deep-sea members of this genus. Within the clade of deep-sea Poseidonamicus, several subgroups are recovered with varying levels of character support. in addition to providing a general framework for understanding morphological evolution in this genus, the results of this phylogenetic analysis have two specific implications for the evolution of sightedness in this genus. First, because Poseidonamicus ocularis is nested deeply within a clade of entirely deep-sea species, its putatively ocular features are probably not related to vision. Second, there has likely been just a single transition from sighted to blind in Poseidonamicus, coincident with its colonization of the deep sea. No support is found for the recent suggestion that sighted shallow-water dwelling Poseidonamicus species may have evolved from blind deep-sea ancestors, although data from additional taxa will be necessary to test this hypothesis more fully.

The mid-Moscovian Izvarino section, Donets Basin, eastern Ukraine, exhibits a complete sedimentological record of siliciclastics (sandstones, siltstones, and calcareous shales) with limestone intercalations and, rarely, coal seams. A multidisciplinary study including microfacies analysis, systematic paleontology (conodonts, fusulinoideans, and ostracodes), biostratigraphy, and paleoecology was focused on the limestones, from limestone L4 through limestone M1, and the adjacent marine shales. Based on sedimentology and fossil associations, the cyclic sediments of the Izvarino section were interpreted as entirely marine deposits of open- and shallow-marine, nearshore and offshore environments with variable terrigenous input.

The well-preserved ostracode faunas are dominated by representatives of the families Amphissitidae, Hollinellidae, Healdiidae, Cavellinidae, and Paraparchitidae. The total fauna is 18 species, of which four are new: Hollinella (Hollinella) granuloba Fohrer, n. sp., Hollinella (Praehollinella) kamenka Fohrer, n. sp., Jordanites krasnodonensis Fohrer, n. sp., and Asturiella donbassica Fohrer, n. sp. The conodont fauna includes 21 species belonging to nine genera and includes one new species: Idiognathodus izvaricus Nemyrovska, n. sp. The conodont faunas are dominated by idiognathodontids. Representatives of Diplognathodus and Neognathodus play a subordinate role. A total of 56 fusulinoidean species referable to 20 genera has been identified; one is new: Eostaffella brazhnikovae Ueno, n. sp.

Conodont and fusulinoidean biostratigraphy led to surprising differences in the age assignment of the Izvarino section and its correlation with the nearby Moscow Basin, Russia. The interval studied is lower Kashirian (Tsninskaya) to middle Kashirian (Narskaya), according to conodonts. It extends to the base of the Podolskian, however, according to fusulinoideans. This discrepancy is possibly related to problems in correlation of the type sections in the Moscow Basin. It calls for reexamination of the mid-Moscovian boundary interval and shows the limits of interbasinal correlations based on a single fossil group.

Norman Gary Lane (1930–2006), president of the Paleontological Society (1987–88) and founder of “Friends of the Echinoderms” (1967), contributed to the lives of each of the authors of this essay. He was an excellent paleontologist, a very fine person, and our friend. He influenced each of us, in ways large and small, and through his wisdom, insight, and sheer human decency he helped each of us to become better scientists, better teachers, and better human beings. We are proud to number ourselves among a great many for whom Gary Lane was a role model.

Naraoiids, defined as lightly sclerotized arthropods with a dimidiate tergum of two sclerites separated by a single transverse articulation, have been found in the Cambrian and Silurian. During the Cambrian they had a wide distribution coinciding with trilobite realms. This pattern may be related to the breakup of a Neoproterozoic supercontinent, probably Pannotia, which implies that naraoiids originated before the Cambrian “explosion.” Based on new observations on the original material from the Burgess Shale (Middle Cambrian, British Columbia), Naraoia halia is reconsidered as a valid species. The validity is further confirmed by a new record of the occurrence of this species in the Chengjiang Lagerstätte (Lower Cambrian, China). In addition, some structures of N. compacta of the Burgess Shale have been reinterpreted. Two more naraoiid species are redescribed in detail from the Chengjiang Lagerstätte on the basis of more than 1,000 well-preserved specimens. Naraoia spinosa shows dimorphism and Misszhouia longicaudata exhibits geographical variation in the overall shape of the dorsal exoskeleton. Naraoiids may have a protaspis-like larva, but the previously assigned protaspis has proven to be a separate taxon, Primicaris. In dorsal view, naraoiids resemble a giant “degree 0” meraspis (i.e., without thorax), and could have originated from different heterochronic processes, neoteny or hypermorphosis. Naraoiids are generally accepted as vagrant benthos. A predatory/scavenging life mode is supported by functional morphology and recent analogues. A healed injury in M. longicaudata suggests that they could be the prey of larger predators, most likely anomalocaridids. We suggest that differences in exopod composition might represent evolutionary changes through the Early–Middle Cambrian. The monophyly of the Naraoiidae is not firmly established. Similarity to liwiids, supposed to be the close relatives of naraoiids, is limited to overall shape. We exclude naraoiids from the Trilobita, though there do exist a number of similarities between them.

Dimorphosiphon talbotorum n. sp. from the Upper Ordovician Bighorn Dolomite of Wyoming is an ancient representative of the erect skeleton-building green algae. Circumstantial evidence indicates that the original skeletal material was aragonite. If so, D. talbotorum and its Ordovician relatives in eastern North America, Europe, and Kazakhstan are reminders that even morphologically simple aragonite producers could thrive during one of Earth's “calcite sea” intervals.

Unlike previously described Ordovician members of its family, the new species is represented by selectively silicified thalli showing three-dimensional details of internal tubes and a highly variable external form. It differs from a similar taxon, D. rectangulare, in having branched as well as unbranched thalli and in morphology of radial tubes. the new species is the first thoroughly documented record of Dimorphosiphon in western North America. Its stratigraphic position in the Richmondian part of the Bighorn Dolomite correlates with previously reported occurrences of the genus in the Red River Formation of North Dakota and Manitoba.

The Wyoming fossils typically occur as scattered components of wackestone and include both silicified and calcitic individuals. the change in skeletal composition from aragonite to calcite apparently took place before tubes decayed, thus preserving tube morphology. Subsequent silicification varied in degree among specimens, probably reflecting differences in permeability of the secondarily calcitic skeletons.

Metrarabdotos Canu, 1914 and the related genera Escharoides Milne Edwards, 1836b, Adeonellopsis MacGillivray, 1886, and Reptadeonella Busk, 1884 were key taxa in the decline of Bryozoa with erect, arborescent colonies and concomitant increase in numbers of species with encrusting colonies in the late Paleogene and Neogene of tropical America. In particular, the abundance, continuity of occurrence, and diversity of Metrarabdotos before its decline have made this genus, over the past 20 years, a model taxon for detailed morphometric studies of fine-scale evolutionary tempo and mode. During the same period, significant new occurrences of both Metrarabdotos and its near relatives have been documented with detailed collections from tropical American areas not represented in the original studies.

In this paper we present a complete reanalysis of the original morphometric data (Cheetham, 1986a), incorporating the new tropical American material and comparative material of selected Metrarabdotos species from Europe and Africa in order to formalize the taxonomy of the genus, many species of which have been in open nomenclature since 1986, and to explore their possible phylogenetic relationships to each other and to Escharoides, Adeonellopsis, and Reptadeonella. The new analysis, with procedures slightly modified from those used in the original analysis, is based on more than twice the number of specimens and 20% more morphological characters. Although the results include changes in species assignments for 13% of the specimens in the original analysis, the pattern of intraspecific morphological stasis previously identified in the tropical American Neogene species, and thus the concomitant interpretation of evolutionary tempo and mode, are unaltered.

Cladistic analysis resulted in a single most parsimonious tree for the 22 tropical American Metrarabdotos species, arranged in two monophyletic crown groups and a paraphyletic stem group. The stem group, ranging from latest Eocene to late Early or early Middle Miocene in age, includes four species, two of which are new: M. aguilerai from Venezuela and M. hispaniolae from the Dominican Republic and Haiti. Crown group A comprises seven species occurring in deposits of Late Miocene to Recent age, four of which are new: M. arawakorum from Venezuela; M. boldi and M. saundersi from the Dominican Republic; and M. coatesi, which occurs in the Dominican Republic, Costa Rica, and Panama. Crown group B, comprising 11 species, ranges from Early Miocene to Recent and includes five new species: M. cubaguaense from Venezuela; M. vokesorum from the Dominican Republic, Costa Rica, and Panama; and M. tainorum, M. jungi, and M. lopezense from the Dominican Republic. Incorporation of six European and African (eastern Atlantic) species, ranging in age from Early Miocene to Recent, into cladograms with the tropical American species produced more variable results in terms of both numbers of alternative trees and the positions of the tropical American species in them. One of these species, M. thomseni from the Pleistocene of Greece, and possibly a second, M. cf. M. maleckii Cheetham, 1968 from the Miocene of the Czech Republic, are new. With one exception, the eastern Atlantic species were placed in more or less basal positions in one or the other of the crown groups, suggesting that, as hypothesized by Cheetham (1968), the “Old World” and “New World” species of Metrarabdotos represent largely independent radiations. The exception is the living species M. cookae Cheetham, 1968, from West Africa and the Cape Verde Islands, which is placed unequivocally in a terminal position in crown group B. Although the three groups of tropical American species correspond in part to subgenera of Metrarabdotos erected by Cheetham (1968), the paraphyly of the stem group and the unresolved identity of the type species of the subgenus apparently corresponding to crown group A suggest that formalizing the taxonomy of these groups is unwarranted at present.

A further cladistic analysis, incorporating the three groups of Metrarabdotos species and Escharoides, Adeonellopsis, and Reptadeonella, yielded two trees, both of which support Cheetham's (1968) hypothesis that Metrarabdotos is more closely related to Escharoides than to Adeonellopsis and Reptadeonella. Escharoides is represented in tropical American Neogene deposits by two species, one of which, E. guraboensis from the Dominican Republic, is new. Of the six tropical American Neogene species of Adeonellopsis, four are new: A. cribrospiramen and A. guraboensis from the Dominican Republic, A. limonensis from Costa Rica, and A. antilleana from Cuba and Jamaica. Three of the six tropical American Neogene species of Reptadeonella, R. buddae from the Dominican Republic, R. collinsae from the Dominican Republic, Panama, Costa Rica, and the southeastern United States, and R. buricaensis from Panama, are also new.

A partial skeleton (including both skull and postcranium) and referred dental material attributable to a new species of Oligo-Miocene kangaroo, Nambaroo gillespieae, are described from the Riversleigh World Heritage Area, northwestern Queensland, Australia. The holotype specimen is one of the oldest articulated fossil kangaroo skeletons yet discovered and includes the first postcranial material definitively attributable to the extinct family Balbaridae. Functional-adaptive analysis (including comparisons with modern taxa) of the hindlimb and pedal elements suggests consistent use of quadrupedal progression rather than true hopping. Robust forelimbs and an opposable first pedal digit (lost in most macropodoids) might also indicate limited climbing ability. Cladistic analysis of 104 discrete cranio-dental and postcranial characters coded for 25 ingroup and one outgroup taxon places N. gillespieae in a plesiomorphic sister clade (also containing other Balbarids and the propleopine Ekaltadeta ima) to all other macropodoids. This result supports recent revisions to the classification of kangaroos, which recognize Balbaridae as the most basal macropodoid family-level taxon.

The Permian–Triassic boundary, examined at two sections in the Southern Alps, occurs ~ 1.0 to 1.5 m above the base of the Tesero Oolite Member of the Werfen Formation in a depositionally continuous sequence of inner neritic carbonates. Lagenide foraminifers from the boundary interval comprise 27 species in 15 genera plus additional unidentified taxa, most of which became extinct during the end-Permian crisis. The only survivors were “Nodosaria” elabugae and unidentified species in Geinitzina and Nodosinelloides, with representatives of the latter two genera being short-term holdovers. The end-Permian lagenide extinction level occurs a few decimeters below the biostratigraphically defined erathem boundary, just above the contact between the Bulla Member of the Bellerophon Formation and the overlying Tesero Oolite Member. Confidence intervals (>96%) for the lagenide extinction at the two sections are 0.03 and 0.04 m thick. Plots of species' stratigraphic abundance versus their last observed occurrences below the estimated extinction intervals at both localities are consistent with abrupt extinction or gradual extinction lasting no more than the time required for 1 m of rock to accumulate. Blooms of the foraminiferal disaster taxa Rectocornuspira kalhori and Earlandia sp. occur in the extinction interval and continue well into the Dienerian part of the Mazzin Member of the Werfen Formation, consistent with a protracted survival phase. A detailed carbon isotope record has been obtained from rocks bracketing the extinction at the well-known Tesero section. The combined microfossil and carbon isotope data indicate that the extinction occurred during an initial negative shift in δ13C. Therefore, the negative excursion is likely to be related to the cause of extinction and unlikely to be merely a consequence of extinction.

Isolated spines and scales from acanthodian fishes are common elements in vertebrate assemblages from the Early Devonian (Emsian) of Arizona, Idaho, Nevada, Utah, and Wyoming. The material described here is from the Sevy Dolomite and lower Grassy Flat Member, Water Canyon Formation, and includes one partially articulated specimen plus isolated fin spines and dermal plates of a new ?climatiid Sevyacanthus elliotti n. gen. and sp.; spines and shoulder girdle elements of a ?climatiid Nodocosta denisoni n. sp.; dentigerous jawbones from at least two ischnacanthiform taxa Ischnacanthus sp. and Cacheacanthus utahensis n. gen. and sp.; fin spines from a ?diplacanthiform Bryantonchus peracutus n. gen.; and scales of Ptychodictyon americanum n. sp. Most of the species appear endemic, although some show a close relationship with older Euramerican taxa (Ischnacanthus, Climatiidae sensu stricto) and younger Baltic taxa (Ptychodictyon rimosum, Nodocosta pauli).

The cephalon of Nephrolenellus multinodus and its stratigraphically higher sister-taxon N. geniculatus passed through the same four successive phases of development: entry into phase 2 is defined by a change from a decrease to an increase in the dynamic pattern of distance between the intergenal spine bases relative to cephalic length; entry into phase 3 is defined by the appearance of genal spines; and entry into phase 4 is defined by the effective isolation of glabellar furrow S3 from the axial furrow. Phase transitions were associated with significant changes in allometric growth patterns of the cephalon. Five instars are identified within the early development (phases 1 and 2) of N. multinodus. Despite the general similarity in cephalic ontogeny, significant interspecific differences in patterns of shape change are documented throughout phases 1, 2, and 3 of cephalic development which, with differences in rates of glabellar shape change relative to size (higher in N. multinodus) and ontogenetic loss of glabellar axial nodes (higher in N. geniculates), demonstrate that evolutionary modification to ontogeny was mosaic and complex. Stratigraphic occurrences and a temporal trend towards increased rate of glabellar axial node loss relative to size in N. geniculates are consistent with a hypothesis that N. geniculates was a direct descendant of N. multinodus. However, ontogenetic data are needed for immediate outgroups of Nephrolenellus to determine whether two potential autapomorphies of N. multinodus, which refute such a hypothesis, are indeed unique to this taxon. Nephrolenellus jasperensis is recognized as a junior synonym of N. multinodus.

The genus Palmoconcha in the family Loxoconchidae of Ostracoda is found in Cenozoic sediments from the North Pacific. the genus Palmoconcha from the North Pacific is divided into two morphological groups: One is the P. parapontica characterized by having a prominent murus along a posterodorsal margin. Another is the P. laevimarginata group characterized by the nonprominent murus. Both the P. parapontica and P. laevimarginata groups contain six species including a new species and six species, respectively. the P. parapontica group is distributed in only northwestern Pacific, whereas the P. laevimarginata group occurs in both the western and eastern sides of the North Pacific. the assemblages occupied by the P. parapontica group, together with Acanthocythereis, Falsobuntonia, and Robertsonites occur from deposits of Japan during the middle Miocene and the early Oligocene climatic cooling. They associate with temperate molluscan faunas, and are considered to have appeared in shelf environments under temperate realms around the Japanese Islands during the Oligocene and Miocene climatic cooling.

Four species including three new species from the Oligocene Waita Formation are also described.

A delicate and well-preserved latest Permian radiolarian fauna was obtained from muddy siliceous rocks and siliceous mudstones in the Dongpan Section, southwest Guangxi, China. the specimens of family Albaillellidae in the fauna have been selected for taxonomic study in this paper. Two genera and 14 species belonging to this family are recognized and described, including three new species and one new subspecies, namely Neoalbaillella minuta, Albaillella flabellata, Albaillella fida, and Albaillella yaoi longa, respectively. This assemblage is correlated to the Neoalbaillella optima Assemblage Zone. Its biostratigraphic significance and the final extinction of Albaillellidae at the end of Late Permian are observed and discussed herein.

The Pennsylvanian fusulinid genus Profusulinella appeared in sub-Arctic North America in Medial Atokan (=Early Moscovian) time, roughly 4–5 My later than its oldest known occurrence in the Eurasian-Arctic province. the genus originated in the latter area in late Early Bashkirian time and then underwent significant diversification, so that by Early Moscovian time a range of shell morphologies existed. the first sub-Arctic North American species in the genus are interpreted as immigrants from Eurasia, with their migration through the Franklinian corridor having been facilitated by generally east-to-west currents during a glacio-eustatic flooding event. Previous work suggested that North American Profusulinella spp. may have derived from a local ancestor such as Eoschubertella. This possibility seems unlikely given that early North American species in Profusulinella are very similar to age-equivalent Eurasian forms, that they differ from North American Eoschubertella in a number of morphologic features, and that there are no known North American intermediates between Eoschubertella and Profusulinella. Fusulinoidean faunas apparently migrated from Eurasia to North America on multiple occasions during Pennsylvanian time. These migrations were an important source of North American diversity, and their recurrence is a dominant theme in fusulinoidean biogeography.

The morphologic variation in Yabeina columbiana (Dawson) was carefully studied using probable topotype specimens from the Marble Canyon-Hat Creek area, southern British Columbia, and the material was compared with related species of neoschwagerinids from various parts of the circum-Pacific region. in the five Marble Canyon-Hat Creek samples examined, we found considerable individual variation in important characters, such as the size of the proloculi, and shape and development of primary and secondary transverse septula in relation to the growth stage of the test. These differences gradually changing from specimen to specimen within and among samples are thought to represent intraspecific variation within this species. Wide individual variations are also found in three different species of Yabeina from Japan, Yabeina sp., Y. kaizensis (Huzimoto), and Y. globosa (Yabe).

Most North American species of Yabeina, such as Yabeina columbiana, have morphological features such as the occurrence of primary and secondary transverse and axial septula in later whorls and the average size of proloculi that reasonably place them as early species in the genus Yabeina. Yabeina columbiana is neither a Lepidolina nor a Colania as some authors had previously thought. Evolved forms of Neoschwagerinidae in the western Cordillera of North America consist of Yabeina cordillerensis Ross, Y. cascadensis (Anderson), Y. columbiana (Dawson), Y. packardi Thompson and Wheeler, and Lepidolina dunbari (Skinner and Wilde).

The earliest North American Yabeina is thought to be Y. cordillerensis from northwestern British Columbia where it is associated with Afghanella sp., Pseudodoliolina sp., and the Wordian ammonoid Waagenoceras. This assemblage is closely comparable to that in the lowest zone of the Midian Stage in the Tethyan realm, the Afghanella robbinsae and Yabeina archaica Zone. the remainder of the known North American Cordilleran species of Yabeina are assignable to the second zone of the Midian Stage, the Yabeina globosa and Lepidolina multiseptata Zone and to the Japanese Yabeina globosa Zone. This zone is considered equivalent to the Capitanian Stage at the top of the Guadalupian Series in southwestern North America. Morphological and faunal analyses of these North American Cordilleran species of Yabeina and Lepidolina and most of the associated species of schwagerinids (for example, Chusenella andersoni, C. atlinensis, and Schwagerina pavilionensis) suggest ages that range through the late Guadalupian. the highest zone of the Tethyan Midian lacks Yabeina and other neoschwagerinids and is based on the ammonoids Eoaraxoceras and Anderssonoceras. This zone is found in sediments of post-Capitanian (post-Guadalupian) age in northern Mexico.

Well-preserved Ordovician conodonts are described from a micritic limestone sequence exposed in the Satun area of southern peninsular Thailand. the faunas represented by these conodonts have North Atlantic Realm affinities and are identical to those reported from North Atlantic Middle to Upper Ordovician successions. Representative conodonts of some of these faunas have also been reported from South China. in ascending order, three conodont zones are discriminated in the Satun sequence: the Pygodus anserinus range Zone, the Baltoniodus sp. cf. B. variabilis range Zone, and the Hamarodus europaeus range Zone. Strata between the B. sp. cf. B. variabilis and H. europaeus zones are not zoned. the conodont-bearing limestone is thought to have been deposited on the continental margin of northeastern Gondwana. Sixteen species belonging to 12 conodont genera, and two unidentified coniform elements, are systematically investigated.