Dinoflagellate cysts from the classic mid-Pliocene Coralline Crag locality of Rockhall Wood, Suffolk are described, representing the first systematic treatment of mid-Pliocene dinoflagellates from the North Sea region. The dinoflagellates broadly reflect warm-temperate surface waters whose temperatures were considerably higher than today. Two assemblages are recognized: an older assemblage (late early Pliocene or earliest late Pliocene, possibly not younger than 3.3 Ma) confined to the Ramsholt Member, and a younger assemblage (predating 2.6 Ma) confined to the overlying Sudbourne Member. Assemblages are characterized by quantitative differences and their succession indicates either: 1) slight cooling within a probable warm-temperate range; 2) a slight increase in open marine influence; or 3) a taphonomic effect perhaps related to a change in bottom currents.

Specimens have been observed using light (LM) and scanning electron (SEM) microscopy, and cyst wall ultrastructure is emphasized as a valuable but underutilized character for Neogene dinoflagellate taxonomy. Operculodinium? eirikianum Head et al. is emended and the following new taxa are proposed: Achomosphaera andalousiensis suttonensis new subspecies, Ataxiodinium zevenboomii new species, Bitectatodinium raedwaldii new species, and Operculodinium tegillatum new species. Geonettia? sp. is new to science but formal description awaits detailed analysis of tabulation.

A moderately diverse assemblage of anthaspidellid demosponges has been recovered from reef-bearing carbonate platform deposits of Early Ordovician, Tremadoc to early Arenig age, in Hubei Province. The sponges occur, in part, in the Tremadoc Fenxiang Formation and, in part, in the lower Arenig Honghuayuan Formation at several localities near Yichang, Xintan, and Liujiachang. Archaeoscyphia nana Beresi and Rigby, 1993, Archaeoscyphia pulchra (Bassler, 1927), and Archaeoscyphia minganensis (Billings, 1859) occur with the new genera and species, Jianghania yichangensis and Velellospongia adnata, and the new species Rhopalocoelia sanxiaensis and Anthaspidella lamellata. This is the first reported occurrence of Anthaspidella in Ordovician rocks of China. Great numbers of these species of fossil sponges have been found in Lower Ordovician outcrops, particularly in the eastern Yangtze Gorge area of Hubei Province.

The Silurian (Wenlockian) Racine Formation of Milwaukee, Wisconsin has yielded 22 types of siliceous and silicified sponge spicules. The spicules occur in bioturbated dolomite mudstone, and they are part of a high-diversity community of small crinozoans, brachiopods, and other taxa. Siliceous desmas of the order Lithistida comprise 79 percent of recovered spicules. Siliceous triaxons of the class Hexactinellida and silicified sexiradiates of the class Heteractinida each comprise 7 percent of spicules. Eleven additional types of siliceous spicules of uncertain taxonomic affinity form 7 percent of the assemblage. No complete sponge skeletons have been observed, probably because of slow deposition and high bioturbation. The Racine spicule assemblage resembles sponge faunas of Silurian offshore deposits in the Canadian Arctic and Great Basin, which suggests moderate bathymetric relief in the Michigan Basin during Wenlockian times.

A thin limestone tongue in the upper part of the Murdock Mountain Formation of northeastern Nevada contains abundant bryozoans of earliest Wordian age. This bryozoan fauna is close to the Kungurian-Kazanian boundary in Russia. These bryozoans are younger than those found in the Kaibab Formation of southern Nevada and slightly older than those in the Gerster Limestone of northern Nevada. This limestone tongue, herein referred to as the Stenodiscus beds, lies below the Thamnosia beds described by Wardlaw in the Murdock Mountain section of the Leach Mountains. This bryozoan-rich limestone tongue serves as a marker unit for mapping the Murdock Formation in the Leach Mountains.

Nine new species of bryozoans occur in the Stenodiscus beds of the Murdock Mountain Formation: Hinganella felderi, Neoeridotrypella schilti, Stenopora parvaexozona, Stenodiscus murdockensis, Dyscritella acanthostylia, Pseudobatostomella irregularis, Streblotrypa (Streblotrypa) elongata, Morozoviella praecurriensis, and Thamniscus erraticus, Hinganella felderi, Neoeridotrypella schilti, Dyscritella acanthostylia, and Streblotrypa (Streblotrypa) elongata are very similar to species described from Russia.

Odontopleurids are a diverse component of rich silicified trilobite faunas recovered from the Wenlock and Ludlow of the Cape Phillips Formation, central Canadian Arctic. Odontopleurinae and Acidaspidinae are common, but Ceratocephalinae and Koneprusiinae are also represented. This work treats all of the Odontopleurinae, with the exception of the genus Acanthalomina Prantl and Přibyl, 1949.

New species of Kettneraspis Prantl and Přibyl, 1949, include the upper Sheinwoodian K. wrightae, the lower Homerian K. lindoei, and the Gorstian K. caldwelli. Rare specimens assigned to Odontopleura Emmrich, 1839, and Radiaspis Richter and Richter, 1917, occur in the Sheinwoodian of the central Arctic.

Edgecombeaspis (type species E. johansonae new species) is proposed for an odontopleurine clade endemic to Laurentia, and in the Silurian restricted to northern Laurentia. Cladistic analysis yields a hypothesis of ingroup structure that is in general calibrated with stratigraphic sequence. An exception is a group of Telychian species from the Mackenzie Mountains, whose stratigraphic sequence was used to support a previous hypothesis of an ancestral-descendant lineage. The cladistic result indicates that the stratigraphic pattern is the inverse of the phylogenetic pattern: the stratigraphically lowest species in the proposed lineage is the most derived, and the highest is most primitive. In addition to the type, new species of Edgecombeaspis include the mid-Sheinwoodian E. jahansi and the lower Homerian E. soehni. Edgecombeaspis apparently became extinct in the Homerian.

The species Kettneraspis lenzi (Chatterton and Perry, 1983) and Radiaspis cf. R. norfordi (Chatterton and Perry, 1983) occur in the central Arctic, and further strengthen previous correlations with strata in the central Mackenzie Mountains, Northwest Territories.

The Mazon Creek Cycloidea contain four taxa: Cyclus americanus Packard, 1885, Cyclus obesus, new species, Halicyne max, new species, and Apionicon apioides, new genus, new species. We conclude, based on a cladistic analysis, that cycloids are specialized maxillopodan crustaceans and a possible sister group to the Copepoda. They may have filled a niche similar to modernday crabs.

Callianassid fossils, preserved within their burrows, collected from Mount Discovery, East Antarctica, provide the first such occurrence in Antarctica as well as evidence for deposition in a shallow marine environment distal to a deltaic system. The age of the specimens, based upon associated dinoflagellate cysts, is late early to middle Eocene.

The Cretaceous and early Cenozoic species of the shallow-marine, warm-water bivalve Plicatula from California (United States) and Baja California (Mexico) are reviewed, and three new species are named. All of these species are representatives of Plicatula and not of the closely related taxon Harpax, which is associated with high-latitude and cool-water regions. The earliestknown Cretaceous species of Plicatula from the study area is P. variata Gabb, 1864, from Lower Cretaceous (Hauterivian Stage) strata in northern California, and our studies show it to be conspecific with Plicatula onoensis Anderson, 1958.

Plicatula allisoni new species is from Lower Cretaceous (Albian Stage) strata in Baja California, Mexico. Plicatula modjeskaensis new species is from Upper Cretaceous (Turonian Stage) strata in the Santa Ana Mountains, southern California. A possible new species from the same strata is also mentioned. A poorly preserved specimen of Plicatula? sp. is known from Upper Cretaceous (upper Campanian to lower Maastrichtian) strata in northern California.

The only Paleocene species of Plicatula from the study area is P. ostreiformis Stanton, 1896, from lower Paleocene strata of Lake County, northern California, and our studies show it to be conspecific with Ostrea buwaldana Dickerson, 1914. The only previously described Eocene species of Plicatula from the study area is P. juncalensis Squires, 1987, from lower middle Eocene (“Capay Stage”) strata of Los Angeles County, southern California. Plicatula surensis new species is from middle lower Eocene (“Capay Stage”) strata in Baja California Sur, Mexico. In addition, there is a Plicatula? sp. from Eocene strata of Baja California Sur, Mexico.

Although Plicatula is of uncommon occurrence north of Baja California, its thermophilic trait makes it useful in recognizing periods of warm climate.

A structured evolutionary pattern emerges from cladistic and stratocladistic analyses of the Calceocrinidae (Echinodermata). These Paleozoic disparid crinoids were dominated by three long-ranging genera, and other genera were derived during endemic radiations in North America and in Europe. Calceocrinid evolution was highly mosaic, including the repetition of morphological transitions, numerous character reversals, and evolutionary independence of characters.

As a family, the calceocrinids make up a highly derived, unique family because the crown is bilaterally symmetrical, is reflexed onto the stem by a hinge between the radial and basal circlets, and was normally situated just above the substratum. The analysis included 23 genera with 17 characters; three were coded as ordered based on previously observed evolutionary trends. Standard cladistic analysis yielded a total of 17,000 equally parsimonious trees. The addition of stratigraphic data through the use of stratocladistic methodology reduced this number to 16 equally parsimonious trees.

Molds of numerous Early Carboniferous echinoderms collected by Christian van de Loo for James Hall in 1867 from four miles south of Crawfordsville, Montgomery County, Indiana and now in the collection of the New York State Museum have been examined using latex casting techniques. Described here are the ophiuroids Vandelooaster plicatilis new genus and species, Schoenaster fimbriatus Meek and Worthen, Aganaster gregarius Meek and Worthen and Lumectaster howelli new genus and species. The types of Calyptactis confragosus Miller are redescribed for comparison. Nine crinoids, a blastoid, and an echinoid are recognized in van de Loo's collection; all have been recorded from Crawfordsville.

Intexalvichnus magnus, new ichnogenus and ichnospecies, is erected for material from the Lower Carboniferous of northwest Ireland. This ichnogenus is characterized by a horizontal primary basal gallery, from which a series of secondary near-vertical shafts originate on either side of the gallery. Intexalvichnus magnus is typified by vertical shafts occurring in offset closely packed pairs on either side of the horizontal gallery, and by their recurved conical morphology. Such material somewhat resembles Phycodes, and in particular “Phycodes” pedum, although overall morphology and mode of construction distinguish I. magnus from Phycodes (including “P.” pedum), warranting separate ichnogeneric status. Although forming monospecific associations, I. magnus occurs within shallow-water deltaic sand-dominated facies with diverse ichnofaunal assemblages. Consideration of ichnofaunas from similar shallow-water paleoenvironments suggests that I. magnus should be globally and stratigraphically widespread. Perhaps because of its relatively large size I. magnus has been overlooked, or referred to other ichnogenera.

Floodplain deposits of the Permian Laguna Polino Member (La Golondrina Formation) of southern Patagonia, Argentina, contain a moderate diversity invertebrate ichnofauna. This member consists of up to 500 m of ripple cross-laminated and trough cross-bedded, medium-grained sandstone and mudstone, with some conglomerate. It records sedimentation in braided fluvial environments with moderate channel sinuosity. The system was characterized by the development of multistory channels, transverse or linguoid bars, and levees. At the Laguna Grande locality, trace fossils were recovered from current-rippled, very fine-grained muddy sandstone beds formed in a pond adjacent to the levee. The ichnofauna consists of a mixed pascichnia, repichnia, and domichnia assemblage composed of Cochlichnus anguineus, Ctenopholeus kutscheri, Helminthoidichnites tenuis, Helminthopsis abeli, and Palaeophycus striatus. These low-energy ponds were more suitable for development of benthic fauna and preservation of ichnofossils than were fluvial channels and point bars. Accordingly, preservation of distinct trace fossil-bearing pond horizons within an otherwise unfossiliferous fluvial succession may be regarded as taphonomic and colonization windows. The colonization history of these beds can be traced through the study of cross-cutting and substrate relationships. Detailed ichnologic analysis suggests the following succession: 1) large Cochlichnus tracemakers colonizing transitional soupgrounds to softgrounds; 2) large and small Cochlichnus, Helminthopsis and Helminthoidichnites formed in softgrounds; and 3) Palaeophycus and Ctenopholeus emplaced in transitional soft to firm substrates. The colonization sequence suggests an ecologic replacement of a surface mobile fauna dominated by nematodes, nematomorphs, and larval insects by a more stationary infauna consisting of adult insects as a result of increasing consolidation. Presence of Ctenopholeus is significant because it represents the second report of this ichnogenus and the first from nonmarine settings.

Reexamination of the chondrenchelyid Harpagofututor volsellorhinus from the Bear Gulch Limestone (Health Formation, Upper Chesterian, Mississippian), has revealed that the preserved fossil pigments are those originally associated with particular, well-vascularized abdominal organs (liver, spleen, and gonads) and major venous sinuses (orbital, gonadal, pelvic). The pattern of pigment localization reflects circulatory pathways of fossilized vessels. This determination was confirmed by comparison of fossil patterns to the visceral and circulatory anatomy of extant chondrichthyans. The arrangement of these pigments conveys strong, and otherwise unavailable, evidence for the internal reproductive features of these sexually mature, Paleozoic chondrichthyans. Under the appropriate preservational conditions the pigments also reveal asphyxia as the cause of death. Thus, the value of these pigments cannot be underestimated. Unfortunately, they are prone to spontaneous and progressive degradation that starts immediately upon excavation. Consequently, it is imperative to record data accurately and in a timely fashion. This report thus introduces the use of a color flatbed scanner as a particularly effective laboratory research tool for the collection and archiving of ephemeral fossil data.

A nearly complete skull of Anchitheriomys from the Miocene of Nebraska allows description of the cranial foramina. In skull characters, Anchitheriomys most closely resembles Agnotocastor and Neatocastor among castorids; it retains primitive features that it shares with eutypomyids (position of the posterior palatine foramina, smooth palatal surface, nearly parallel tooth rows, retention of dP3) combined with derived features (elongate rostrum, procumbent incisors) that are shared only with Agnotocastor and Neatocastor. A new subfamily, Agnotocastorinae, is erected for this group of primitive beavers.

The record of fossil land mammals from Antarctica has been restricted previously to the middle levels of the Eocene-?early Oligocene La Meseta Formation in Seymour Island, Antarctic Peninsula. This mostly shallow-marine sequence was divided informally into seven subunits (Tertiary Eocene La Meseta or TELM 1 to 7) by Sadler (1988). Land mammals, representing South American lineages of marsupials, edentates, and ungulates were recovered from TELM 3, 4, and 5 (Marenssi et al., 1994; Vizcaíno et al., 1994). The purpose of the present note is to report the discovery of a well-preserved ungulate tooth from the uppermost level of the La Meseta Formation (TELM 7) and to discuss its paleoenvironmental implications.

The purpose of this note is to record the availability for research of highly fossiliferous sediment from a late Pleistocene terrestrial deposit in the Caribbean. The Red Hills Road cave in the parish of St. Andrew, northwest of Kingston, Jamaica (for more precise locality information, see Donovan et al., 1995, p. 12-15) is a late Pleistocene, essentially unstratified, cave deposit. The terrestrial fauna from this site includes diverse vertebrates (Savage, 1990; D.A. McFarlane and R.D.E. MacPhee, research in progress) and gastropods, associated with rare arthropods including millipedes (Donovan and Veltkamp, 1994), isopods, ostracodes and claws of non-marine crustaceans (J. S. H. Collins, research in progress).

The editor of the Zoological Record has kindly informed me that the generic name Polysiphonia Finks, 1995, (class Calcarea, order Murrayonida, family Maeandrostiidae) (Finks, 1995, page 4) is preoccupied (Mrs. M. Joan Thorne, personal commun., 1996). I therefore rename it Polysiphonaria.