Calcified cyanobacteria are of considerable research value for reconstructing the ecology of Paleozoic and Mesozoic benthic communities on carbonate platforms due to their ability to produce oxygen and fix nitrogen and CO2. The diversity and abundance of calcified cyanobacteria was initially suggested to have declined in the Middle and Late Ordovician, although more recent work suggests that complex and diverse assemblages persisted throughout the Ordovician. Here, calcified cyanobacteria and associated microfossil flora from the Middle and Late Ordovician of the Ordos Basin, North China Block, are systematically described for the first time based on 1330 thin sections from seven outcrop profiles and four drill cores. In total, there are 18 species belonging to 16 genera, including a new species, Proaulopora ordosia n. sp. Girvanella, Subtifloria, Acuasiphonoria, Xianella, and Oscillatoriaceae gen. indet. are assigned to Osillatoriales of cyanobacteria; Ortonella, Hedstroemia, Cayeuxia, Zonotrichites, Proaulopora, and Phacelophyton are assigned to Nostocales of cyanobacteria; and Garwoodia, Renalcis, Izhella, Rothpletzella, and Wetheredella are assigned to calcified Microproblematica. A literature survey of Ordovician microfloral assemblages shows that cyanobacteria and associated microfossils occur in reef, open platform, lagoon, and tidal facies. Most genera occur on at least two independent blocks, and many have a cosmopolitan distribution in similar sedimentary facies. Our research suggests that calcified cyanobacteria and associated microfossils formed complex ecosystems and played greater ecological roles on carbonate platforms during the late Middle and Late Ordovician than was previously thought.

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Faunules of largely hexactinellid sponges have been collected from siltstones of Early Silurian Wenlock or latest Landovery age within the upper Road River Group from northern British Columbia. The assemblages include the new species: Protospongia columbiana, Hexatractiella pseudonevadensis and Cyathophycus akiensis. Other taxa described include the hexactinellids Protospongia conica Rigby and Harris, 1979, Hexatractiella nevadensis (Rigby and Stuart, 1988), Diagoniella sp., Gabelia pedunculus? Rigby and Murphy, 1983, and a specimen of the monaxonid demosponge Wareiella typicala Rigby and Harris, 1979. Also included is a fragment of what must have been a steeply obconical-cylindrical hexactinellid sponge of uncertain taxonomy; it has a skeleton of robust hexactines in an unquadruled net, above a root-tuft of 10-20 spicules. Other sponge impressions include small circular clusters of hexactines with radiating, to basketlike patterns and somewhat similar, isolated and dissociated, long probably roof tuft spicules and possible basal root tuft rosettes of monaxons. The faunules are similar to other outer continental margin, black shale, sponge assemblages of the Early Paleozoic Era, and include elements previously described from northern British Columbia and central Nevada.

Five taxa of amynodontid rhinoceroses have been named from Kazakhstan. We consider only two of these valid, and recognize three amynodontid taxa from Paleogene deposits in Kazakhstan: Cadurcodon ardynensis (=Cadurcodon zaisanensis; =Amynodon tuskabakensis) from the upper Eocene (Ergilian)-lower Oligocene (Shandgolian) of the Zaysan basin, Zaisanamynodon borisovi, from the Ergilian of the Zaysan basin and Cadurcodon kazakademius, from Shandgolian strata in the vicinity of the Chelkar-Teniz lake basin. Gigantamynodon akespensis, from the upper Oligocene north of the Aral Sea is a rhinocerotid, not an amynodontid. Close similarity of the amynodontids of Kazakhstan to those of Mongolia and China supports direct correlation of Ergilian and Shandgolian strata across Asia.

Small bioherms in the uppermost Tansill Formation and Capitan Limestone in the northern Guadalupe Mountains, New Mexico, have been informally interpreted as sponge reefs by past workers. Samples collected during the present cycle of field work in 1993 and 1994 suggest that some of these isolated carbonate mounds have a different origin. Guadalupe Mountains complexes have been recognized for many years as outstanding models for interpretation of reefs, reef facies, and reef faunas (for example, King, 1948; Newell et al., 1953; Achauer, 1969; Yurewicz, 1976, 1977; Babcock, 1977; Kirkland et al. 1993).

Pre-pleistocene fossil vertebrates are rare fossils in the Antillean region. The majority of vertebrate deposits found in the West Indies are of Late Pleistocene age, usually, but not always (MacPhee et al., 1989), dating from after the last interglacial. These faunas are cave and fissure accumulations of disarticulated bones of small terrestrial vertebrates, particularly rodents, birds, and lizards. In contrast, pre-Quaternary vertebrates of the Caribbean islands are particularly poorly known. For example, Jamaica, which has one of the most extensively studied fossil records in the region, has hitherto produced only three Tertiary vertebrates, all aquatic and hitherto known only from unique specimens. These include: the late Early Eocene sirenian Prorastomus sirenoides Owen, 1855, originally described on the basis of the skull, mandible, and atlas vertebra (for a recent discussion of this species, see Savage, 1977); the lower jaw of the early Middle Eocene crocodilian Charactosuchus kugleri Berg, 1969; and a fragment of needlefish jaw from the Pliocene (Caldwell, 1966). It is therefore significant to report the discovery of an early Middle Eocene sequence in which bones are not uncommon, including a bone bed that has produced a moderate diversity of aquatic (marine?) taxa.

An investigation of middle Eocene calcareous nannofossils from Deep Sea Drilling Project Sites 162 and 361 has revealed a new species, Discoaster praebifax, and prompted the emendation of Discoaster bifax Bukry. Based on their morphologic similarities and stratigraphic relationship, D. praebifax is suggested to be the ancestor of D. bifax. Because the new species closely resembles D. bifax, the use of the latter as an index species for Subzone CP14a should be cautioned. The first occurrence of D. praebifax is, however, a potentially useful datum in Zone CP12.

The fissurellid, haliotid, and scissurellid gastropods described herein are representatives of a diverse, but poorly documented, molluscan assemblage from the Upper Cretaceous carbonate-platform deposits of the Caribbean Faunal Province. Among the Fissurellidae, the Emarginulinae are represented by Emarginula pojetai n. sp., E. marchmontensis n. sp., E. sp., Puncturella (Alatrix) leesi n. sp., and P. (A.) sp.; the Diodorinae by Diodora decussata n. sp., Diodora hazeli n. sp., Diodora? pedinostoma n. sp., and D. sp.; the Fissurellinae by Fissurella kollmanni n. sp. Haliotis antillesensis n. sp. is only the second verifiable member of the family Haliotidae to be described from the Cretaceous and Scissurella marchmontensis n. sp. represents the first record of the Scissurellidae in that period.

Two species and genera of pteraspidids (Agnatha, Heterostraci), Blieckaspis priscillae n. gen., and Panamintaspis snowi n. gen. and n. sp., together with two undetermined species, are described from the lower part of the Lippincott Member of the Lost Burro Formation, southeastern California. The sharing of similar faunal elements with the Early Devonian assemblages of the Sevy Dolomite and Water Canyon Formation of Utah and Nevada, respectively, together with stratigraphic constraints on the age of the Death Valley fauna, suggest that these assemblages are age equivalent and have a late Emsian (inversus–serotinus Zones) age. The vertebrate-bearing unit of the Lippincott Member is interpreted as a channel-fill deposit laid down in an estuarine environment with low or fluctuating salinity.

Five species of rostroconchs are known to occur in six Mississippian units in Ohio. Aphelakardia alternistriata (Herrick) n. gen. and Hippocardia herricki n. sp. are present in the Meadville and Wooster Members, Cuyahoga Formation (Osagean). ?Hippocardia sp. occurs in the Meadville Member. Pseudomulceodens cancellatum (Hyde) n. gen. is known from the Byer Member, Logan Formation, and Wooster and Blackhand Members, Cuyahoga Formation (Osagean). Bransonia hydei n. sp. occurs in the Maxville Limestone (Chesterian). An unidentified taxon occurs in the Allensville Member of the Logan Formation.

Three new species and one new subspecies of Streptognathodus were discovered during systematic stratigraphic study of conodonts from Virgilian cyclothems of Kansas. Streptognathodus bitteri n. sp. characterizes faunas from the middle of the Plattsmouth Limestone but ranges into the upper Wabaunsee Group. Streptognathodus brownvillensis n. sp. is restricted to the Brownville Limestone. Streptognathodus holtensis n. sp. occurs in the Holt Shale, as well as the Church, Burlingame, Wakarusa, and Elmont Limestones. A new subspecies of S. pawhuskaensis (S. pawhuskaensis deflectus) was recovered from the lower half of the Shawnee Group.

Additional Whiterockian gastropods are described from the Antelope Valley Formation of Nevada. A new genus with affinities to Oriostoma is described as well as the new species Clathrospira glindmeyeri, Trochonemella antelopensis, and Raphispira martinensis. The lower ranges of Clathrospira Ulrich in Ulrich and Scofield and Trochonemella Okulitch, the species Liospira americana Billings and Raphistomina lapicida (Salter) are extended to the Whiterockian. The ranges of Raphispira Perner and the family Oriostomatidae Wenz are tentatively extended downward to the Whiterockian.

The marine gastropod genus Struthiochenopus appears first in the late Cretaceous of the Antarctic Peninsula. Until the Oligocene only one or two species were extant at the same time. This changed drastically in the early Miocene when at least three species were living coevally in southern South America. A possible fourth early Miocene species, Struthiochenopus sp., is known from Ipún Island, Chile, but its identification remains unclear. Another taxon, S. echtleri new species, described from Neogene deposits of Mocha Island, Chile, has no precise age available but it is likely the latest survivor of the genus.

A new spinicaudatan species, Estherites? jocelynae new species, is described from more than fiftyspecimens collected from the Medicine Lodge Formation (early Oligocene) of the Beaverhead Basin in southwestern Montana, USA. This is the first spinicaudatan species reported from Cenozoic strata of North America and is the second-youngest fossil clam shrimp described globally. The new species extends the range of the superfamily Estheriteoidea into the Paleogene. Carapaces of E.? jocelynae n. sp. are preserved as a calcium carbonate replacement of the original chitin-calcium-phosphate structure, which is an uncommon style of preservation for spinicaudatans. The unique preservation coupled with the range extension suggests that the sparse Cenozoic fossil record of spinicaudatans may be partly attributable to preservation bias related to geochemical conditions rather than exclusively to diversity decline following the end-Cretaceous mass extinction. The presence of E.? jocelynae n. sp. in the Medicine Lodge Formation indicates that lakes in the Beaverhead Basin experienced seasonality and fluctuating lake levels with at least some drying at the lake margins. The ecological inferences support previous paleoenvironmental interpretations based on paleobotanical and other faunal evidence.

Studies of paleoenvironments have commonly focused on large mammalian herbivores such as ungulates. Many localities, however, have yielded large numbers of small mammalian herbivores, including lagomorphs and rodents. These fossils represent an untapped paleoecological resource. However, the fossils are often in the form of isolated teeth, and microwear analysis cannot be used due to taphonomic alteration. As a result, we use ungulate gross dental wear as a model. The dental wear features of extant western Canadian lagomorphs are identified and used to create dietary categories that can be applied to make predictions about the diets of extinct forms. The Horse Local Fauna of the Cypress Hills Formation of Saskatchewan has yielded approximately 2,500 fossil specimens, of which nearly 300 are lagomorphs. Two leporid species (rabbits and hares) are present in the Horse Local Fauna, Palaeolagus temnodon and Megalagus brachyodon. Qualitative analysis of the gross dental wear of the lagomorphs of the Horse Local Fauna indicates that M. brachyodon was mainly folivorous and P. temnodon was primarily frugivorous, suggesting that the contemporaneous ecosystem was tree dominated. Gross dental wear analysis allows the use of small herbivores and isolated teeth in paleoecological studies. Studying the diets of small herbivorous mammals will allow more nearly complete reconstructions of past environments and will become increasingly important as more detailed reconstructions are required by paleontologists.

E. H. Sellards (1916, p. 96) applied the new binomen “Hipparion minor” to the very small hipparionine horse from the early Pliocene Bone Valley District of peninsular Florida. Since the gender of Hipparion is neuter, the ending of the species name must be amended to agree with it (Articles 32d and 34b, ICZN, 1985), and thus the correct spelling of the original species name for this taxon is Hipparion minus Sellards. This correction was previously instituted by Hay (1930, p. 693). However, this name is a primary junior homonym of Hipparion minus Pavlow, 1890, a Eurasian species of horse, and as such is permanently invalid (Articles 52b, 53c(ii), and 57b, ICZN, 1985). Hipparion minus Pavlow was in common use for small hipparionine horses from Russia and Greece during the first quarter of this century. Although now generally regarded as a nomen dubium, it was used as a valid subspecies as recently as Pirlot (1956). Its present disuse in no way affects the condition of primary homonymy between the two species names.

A partial skeleton, including a skull with part of the axial skeleton, part of a second skull, and fragments of ribs have been recovered from the Sinemurian of the Sandilands Formation exposed at Kennecott Point in the northwestern Queen Charlotte Islands. This material is the most complete Early Jurassic collection from North America reported to date; other occurrences include a forefin from the Nordegg Formation (Sinemurian) of Alberta positively identified as Ichthyosaurus (McGowan, 1978) and vertebral centra from the Nicely Formation (Pliensbachian), Oregon, not assigned conclusively to a genus (McGowan, 1978). The discovery of ichthyosaurs in the allochthonous insular belt of British Columbia adds weight to the contention that ichthyosaurs were cosmopolitan in their distribution (McGowan, 1978; Orr, 1986).

In the El Castro Formation, cropping out on the Asturian coast of northern Spain, two fossiliferous horizons have been studied. Above the basal one, containing the Llandeilian brachiopods Tissintia cf. T. convergens and Howellites? sp., a new horizon of estimated Ashgillian age has been identified that has yielded the new brachiopod species Mcewanella vulcanica and Hesperinia asturica. The new species of Mcewanella, close to the Irish Rawtheyan Mcewanella dorsisulcata, is characterized by a great delay of the insertion of costellae, which gives many adults a strikingly costate ornament for this genus. Hesperinia was, up to now, poorly known from a small number of specimens from the Llanvirnian Tank Hill Formation in Nevada; thus, the new record, besides allowing a better understanding of the genus and its relationship with other oepikinids, extends its known time span to the Late Ordovician. These two species were dwellers on a low-energy bottom formed of loose sand and gravel supplied by nearby volcanic eruptions. The ash-flow depositional pattern of these sediments would have had lethal effects on the brachiopod communities, periodically causing their destruction. These species of the genera Mcewanella and Hesperinia are new representatives of the immigration of North American and Northern European warm-water faunas into the circumpolar Mediterranean Province during the Late Ordovician.

“Phylloid algae” (Pray and Wray, 1963, p. 209) are problematical fossils that occur profusely in Pennsylvanian carbonate microfacies in the United States (Wray, 1968) and many other parts of the world (Mamet, 1991). Taxonomic affinities of most phylloid alga are uncertain. The questionable affinities of phylloid algae and related paleoecologic problems have been summarized by Riding (1977), Wray (1979), and James et al. (1988) and will not, therefore, be repeated here. Our ability to establish probable taxonomic affinities of fossil calcareous algae is dependent largely upon the recognition of their internal microstructures. Because phylloid algae are very susceptible to dissolution and neomorphism, their original internal microstructures are rarely well preserved.

A flat, thin, platelike operculum from the Antelope Valley Limestone of central Nevada fits the aperture of the shell of Palliseria robusta; abundance of these shells at the locality where the operculum occurs further supports its association with P. robusta. The operculum shows no evidence of spiral growth; its inner surface has one muscle prong. Palliseria shells are present in Nevada in enormous numbers, but opercula are known from only three localities. Because these platelike opercula are less robust than the coiled shells, most opercula may have been destroyed by wave and current movements after death of the animals.

Arthrophycus alleghaniensis is a well-known trace fossil common in the lower Silurian of the Appalachian Basin, eastern U.S.A. Despite the distinctive morphology of this trace, with few exceptions, hypotheses about the nature of the tracemaker have not extended beyond that of a long-bodied, segmented organism. A single organic compression of a long-bodied arthropod discovered in shale interbedded with sandstones containing A. alleghaniensis in the Silurian (Llandovery) Tuscarora Formation at Mann Narrows, Pennsylvania is described. The specimen preserves evidence of two trunk tagmata: an anterior tagma with tergites extending into broad, rectangular pleurae, and a posterior tagma bearing long, curved spines. Head and appendages are not preserved. The new arthropod, Pleuralata spinosa n. gen. n. sp., matches the size and general morphology required for an A. alleghaniensis tracemaker. Precise systematic affinities of this new arthropod could not be determined. This discovery supports the conclusion that the tracemakers of various Arthrophycus ichnospecies are likely poorly preserved, and presently unknown, members of the Ecdysozoa.