Carbonaceous bedded cherts of the late Neoproterozoic (Cryogenian) ∼800 to 750 Ma old Chichkan Formation of South Kazakhstan contain an abundant, diverse assemblage of exquisitely preserved microorganisms. Like many Proterozoic microbiotas, the Chichkan assemblage is dominated by prokaryotic cyanobacteria, both filamentous (oscillatorialeans and nostocaleans, represented primarily by cellular trichomes and empty sheaths) and coccoidal (chroococcaleans and pleurocapsaleans, including solitary, colonial, and stalk-forming specimens). However, unlike Proterozoic microbiotas reported from peritidal settings, the Chichkan fossils, permineralized in cherts deposited in the open shelf facies of the formation, include diverse microscopic eukaryotes: vase-shaped testate amoebae, spiny (acanthomorphic) phytoplanktonic unicells, large (up to ∼1 mm diameter) megasphaeromorphic acritarchs, and sausage-shaped vaucheriacean green alga-like filaments.

Given the composition of this biota and the presence in it and similarly aged assemblages of numerous taxa typical of late Neoproterozoic deposits (e.g., Cerebrosphaera, Jacutianema, Melanocyrillium, Stictosphaeridium, Trachyhystrichosphaera, and Vandalosphaeridium), the Chichkan Lagerstätte appears representative of the Cryogenian biota as now known, thereby documenting the status of the marine biosphere at a time closely preceding the radiation of the Metazoa. As such, we interpret this and other coeval mixed assemblages of prokaryotic and eukaryotic microfossils as representing an evolutionary stage transitional between the predominantly prokaryote-dominated Precambrian and the eukaryote-dominated Phanerozoic biospheres.

As reported here, the Chichkan assemblage is composed of 39 taxa (of which two forms are described informally) that are assigned to 23 genera of microscopic prokaryotes and eukaryotes and that include two new species: Polybessurus crassus n. sp. and Vandalosphaeridium koksuicum n. sp.

Precambrian microbiotas, such as that permineralized in bedded and stromatolitic cherts of the late Neoproterozoic, 750- to 800-Ma-old, Chichkan Formation of South Kazakhstan, have traditionally been studied by optical microscopy only. Such studies, however, are incapable of documenting accurately either the three-dimensional morphology of such fossils or their chemical composition and that of their embedding minerals. As shown here by analyses of fossils of the Chichkan Lagerstätte, the solution to these long-standing problems is provided by two techniques recently introduced to paleontology: confocal laser scanning microscopy (CLSM) and Raman imagery. The two techniques are used together to characterize, in situ and at micron-scale resolution, the cellular and organismal morphology of the thin section-embedded organic-walled Chichkan fossils. In addition, Raman imagery is used to analyze the molecular-structural composition of the carbonaceous fossils and of their embedding mineral matrix, identify the composition of intracellular inclusions, and quantitatively assess the geochemical maturity of the Chichkan organic matter.

CLSM and Raman imagery are both broadly applicable to the study of fossils, whether megascopic or microscopic and regardless of mode of preservation, and both are non-intrusive and non-destructive, factors that permit their use for analyses of archived specimens. They are especially useful for the study of microscopic fossils, as is demonstrated in this first in-depth study of diverse taxa of a single Precambrian microbiota for which they provide information in three dimensions at high spatial resolution about their organismal morphology, cellular anatomy, kerogenous composition, mode of preservation, and taphonomy and fidelity of preservation.

We provide the first detailed systematic taxonomy and paleoecological investigation of late Paleozoic brachiopod faunas from Korea. Specifically, we focus on the brachiopods from the Geumcheon-Jangseong Formation, the lower part of the Pyeongan Supergroup in the Taebaeksan Basin. The formation yields a variety of marine invertebrate fossils, including brachiopods, molluscs, echinoderms, corals, fusulinids, and conodonts. Diverse brachiopods are described from six siliciclastic horizons of the formation at three localities, including 23 species belonging to 20 genera with two new species: Rhipidomella parva n. sp. and Stenoscisma wooi n. sp. Three brachiopod assemblages of the late Moscovian (Pennsylvanian) age are recognized based on their species compositions and stratigraphic distributions, namely the Choristites, Rhipidomella, and Hustedia assemblages. The brachiopod faunal composition varies within each assemblage as well as between the Assemblages, most likely reflecting local paleoenvironmental and hence paleoecological differences. The Choristites Assemblage includes relatively large brachiopods represented by Derbyia, Choristites, and Stenoscisma and may have inhabited open marine to partly restricted marine environments, whereas the Rhipidomella and Hustedia Assemblages consist of a small number of small-sized brachiopods living in lagoonal environments. The Choristites Assemblage shows a close affinity with Moscovian brachiopod assemblages in the eastern Paleo-Tethys regions, especially the Brachythyrina lata–Choristites yanghukouensis–Echinoconchus elegans Assemblage of North China, whereas the Rhipidomella and Hustedia assemblages both exhibit strong endemism.

Rudists are a principal biotic component of Cretaceous carbonates in Tibet and in the Western Tarim Basin. Barremian to Maastrichtian carbonate units are widespread on the northern margin of the Indian Plate and in Tethyan tectonic slices that were welded onto Eurasia in successive stages during the Late Cretaceous and Paleogene. In far northwestern Tibet, Barremian-Cenomanian endemic rudists and cosmopolitan orbitolinid foraminifera occupied isolated carbonate platforms in the eastern Tethys. Rudists, corals, and stromatoporoids composed bioherms up to 10 m thick and several kilometers in lateral extent. A unique endemic requieniid rudist, Rutonia, is compared to morphologically similar but older, less derived genera. Associated specimens in this assemblage are indeterminate requieniid valves, monopleurids, and two genera with three radiolitid species that are re-described and taxonomic positions re-evaluated. In southern Tibet, mainly endemic Campanian-Maastrichtian radiolitid rudists and cosmopolitan larger benthic foraminifera contributed to carbonate shelves on the northern Indian Plate near the Cretaceous equator. In the Western Tarim Basin Cenomanian strata yield Tethyan rudist species.

Coiling morphometric analysis using the three-dimensional morphology Raup diagram shows that Requieniidae valves in contact with the substrate are convergent with the basic gastropod shell. More derived strongly coiled, younger requieniids were adapted to encrusting or semi-infaunal habits. Stratigraphic analysis confirms that Requieniidae diversity crises coincided with Cretaceous oceanic anoxic events

Two end members of valve geometry each appear to be primitive and derived characters respectively and separate the family Requieniidae into two clades that are here recognized as two new subfamilies. The end members are defined by the coiling geometry, whether the spire is close to the plane of commissure or it is translated along the coiling axis and by myophore structures. The older matheroniform clade has a low spirogyrate LV that is translated slightly from the commissure along the coiling axis; this group is composed of Matheronia (and its subgenus Monnieria), Hypelasma, Lovetchenia, Rutonia, and Kugleria. Genera in the younger clade have a tall trochospiral LV that is translated along the coiling axis and consists of Requienia, Toucasia, Pseudotoucasia, Apricardia, Bayleoidea, and Bayleia. Claditics support these relationships.

Four species of rugose corals (one new) are described from the Silurian of the Kurosegawa Terrane, Southwest Japan. They are Neobrachyelasma japonica n. sp., Pseudamplexus sp., Amsdenoides sp., and Amplexoides sp. aff. A. chaoi (Grabau, 1925). These species occur in the Middle Member of the Gionyama Formation, which is Late Llandovery to Early Ludlow in age. Neobrachyelasma is reported for the first time from Japan. This genus occurs in the Lower Llandovery to Upper Silurian of Japan, South China, Kazakhstan, and the Altai and might be distributed only in South China and Japan during the Late Llandovery. Its occurrence in Japan may support a paleogeographic proximity of ‘Proto-Japan’ and the South China Block during the Silurian.

Morphometric analyses of shell morphology in the Pennsylvanian nautiloid Metacoceras mcchesneyiMurphy, 1970 (Cephalopoda, Mollusca) recovered from coal mines in Madison Township, Columbiana County, Ohio, USA, reveal the ontogenetic change from hatching to maturity as well as intra-specific variation of shell morphology. The shell shape of M. mcchesneyi has isometric relationships, and the umbilicus diameter between umbilical shoulders has a positive allometric relationship with shell diameter. These show that the relative whorl shape was constant through the ontogeny, but the umbilicus became relatively broader with growth. The siphuncle position moved from a ventro-central position toward the center with growth until 420° of the total rotational angle had been attained. A constriction was recognized on the early whorl at 9.5 mm in shell diameter, and the interval angles of succeeding septa were changed at the 5th septum, indicating that hatching occurred at this diameter. The ventral apertural wall, the disappearance of ornamentation toward the last preserved aperture, and the last whorl separating from the previous whorl indicate that M. mcchesneyi attained maturity at ca. 70 mm in shell diameter. Most characteristics of shell morphology in M. mcchesneyi (the relative shell shape and ornamentation through ontogeny) are comparable to those in modern and younger fossil nautilids, irrespective of taxonomy and age, supporting the conclusion that evolutionary rates of shell morphology are conservative in nautilid history.

Articulated meraspid and holaspid exoskeletons of Guangxiaspis guangxiensis from the Guole Township, Jingxi County, Guangxi Province, China, are preserved in mudstone deposited during an obrution event. The species has a short dorsal pre-cranidial median suture that splits ventrally into a pair of posteriorly divergent connective sutures. The rostral plate of G. guangxiensis is thus triangular in outline, as in the co-occurrent Shergoldia laevigata, which also bore a conterminant hypostome. These two taxa appear to be closely related. The cephalic venter of Shergoldia laevigata has recently been interpreted to suggest a diphyletic origin of the median suture within the order Asaphida, but Guangxiaspis guangxiensis, Shergoldia laevigata and other tsinaniid trilobites display several characters reminiscent of members of the non-asaphide suborder Leiostegiina. These include swellings adjacent to the margins of the L1 glabellar lobe, the shape and furrows of the glabella, a semi-circular pygidium with a long and thin axis, and macrospinous first opisthopleurae of the holaspid pygidium. Based on these characters and on other new information on the early ontogeny of other tsinaniids, all these taxa likely belong within Leiostegiina. This suggests that the median suture arose independently in corynexochide and asaphide trilobites. The degree of convergence between S. laevigata and members of the derived asaphide family Asaphidae was remarkable. Guangxiaspis guangxiensis shows marked morphological change during both meraspid and holaspid ontogeny and might include more than a single morphotype.

Environmental variability exerts a substantial control on massive, free-living, colonial corals such as Manicina areolata, influencing their shape and size as well as other characters, such as base morphology and colline complexity in meandroid forms. This species is well adapted for life in shallow, wave-swept waters due to its self-righting capabilities. Two different ecophenotypes of M. areolata, as defined by overall shape and base morphology, are present in two approximately coeval Pleistocene localities (PBA Quarry and Holey Land Canal) in southern Florida. These differences reflect adaptation to two depositional settings. Corallum size, shape, and oral complexity allow clear differentiation between these two environments. Greater corallum size, as primarily manifested by significantly greater height, tends to accompany increased grain size. The basal area and weight per cm² of the coralla appear to be primary limiting factors in M. areolata's growth by controlling the coral's ability to self-right after overturning or causing sinking into less cohesive substrates. Complexity of confluent corallites increases with increasing size and colony volume. Thus, complexity of valley and colline patterns on the oral surface increases as a function of base area, so that collines developed on smaller, soft-substrate-inhabiting colonies are characteristically less complex than are those of larger, higher colonies. These complexities and variation in shape are apparently related to environmental conditions, predominantly substrate, water depth, and physical energy, resulting in recognizable ecophenotypes.

Conoidal shells of Cornulites celatus n. sp. occur commonly within host coralla of Propora conferta Milne-Edwards and Haime, 1851, sensu lato, from the Laframboise Member of the Ellis Bay Formation (Ashgill: Upper Ordovician) at Pointe Laframboise on western Anticosti Island. Examples have also been found at the same locality in the tabulate corals Paleofavosites sp., Acidolites arctatus Dixon, 1986, and A. compactus Dixon, 1986, and the stromatoporoid Ecclimadictyon sp., but not in other associated tabulate coral species. Growth interference between the shells and their hosts indicates a commensal relationship. C. celatus apparently had a more limited paleoenvironmental range than its principal coral host species, which occurs abundantly elsewhere on the island without its endobiotic partner. The diagnosis of Cornulites is emended to include forms having a two-layered shell wall with a distinctive outer layer consistently preserved as prismatic calcite. This new species extends the known stratigraphic range of cornulitids in commensal relationships with corals and stromatoporoids from the Silurian back to the Upper Ordovician.

Five new species of Early Permian (late Sakmarian to Kungurian) colonial corals from eastern Nevada and southeastern California, one assigned to a new genus, are described and illustrated. These include Heintzella playfordi n. sp. from the Arcturus Formation in Nevada and the Darwin Canyon Formation in California, Paraheritschioides fergusonensis n. sp. from the Ferguson Mountain and Bird Spring formations in Nevada, and Wendoverella arca n. gen. and n. sp., Permastraea nevadensis n. sp., and Pararachnastraea moormanensis n. sp. from the Pequop Formation in eastern Nevada. These new taxa are distinct from all previously described species, but most are related to other species in the North American miogeocline. Wendoverella arca n. sp., however, is unlike any other species described from North America but is quite similar to a Russian species, indicating faunal communication between the Ural Mountains and the Cordilleran miogeocline at least into Artinskian time.

Re-evaluation of teeth referred to the Late Cretaceous shark Ptychodus polygyrus from North America are hereby determined to be synonymous with another species having similar tooth morphology, Ptychodus marginalis Agassiz. Ptychodus marginalis differs from P. polygyrus by having an elevated and rounded tooth crown with transverse ridges restricted centrally on the apex of the crown with a clearly defined marginal area. The type specimen of P. marginalis was described from Middle Cenomanian to Middle Turonian deposits in the English Chalk, and teeth possessing identical tooth morphologies are found within contemporary units in North America, whereas teeth having the typical P. polygyrus morphology are restricted to Late Santonian-Early Campanian deposits.

A rare new turban-shaped basal Middle Cambrian gogiid eocrinoid, Turbanicystis inflatus new genus and species is described from the Kaili Formation (Kaili Biota), Guizhou Province, China. It co-occurs with three other markedly different gogiids, Sinoeocrinus, Globoeocrinus, and Balangicystis, and is part of a unique Middle Cambrian community that is dominated by echinoderms.

The rudist bivalve Durania aguilae Adkins was described from the Mendez Formation in Mexico and originally attributed to the Santonian. We revise this species and show that it belongs to the genus Chiapasella Müllerried. We also recognize that Chiapasella aguilae (Adkins) is a senior synonym of Chiapasella trechmanni Mitchell and Gunter, an important biostratigraphic indicator in the late late Maastrichtian of Jamaica. Chiapasella aguilae is therefore an important late late Maastrichtian marker fossil that has been recorded from Jamaica, Mexico, and Cuba.

We report on well-preserved upper and lower jaws found inside the body chambers of two specimens of Didymoceras nebrascense (Meek and Hayden, 1856) from the Upper Cretaceous Pierre Shale of the USA. The finds are described and compared to existing material, and their possible functions are discussed.

A new species of the marsupial Peradectes is described from the early Eocene Nanjemoy Formation of Virginia. It is the first Tertiary marsupial known from the Atlantic Coastal Plain north of Florida. The smallest species of Peradectes, it is more closely related to species known from the Western Interior of North America than to contemporaneous European species.

We provide clarification of the nature of the junction between cup and arms in Titanocrinus sumralli Guensberg and Sprinkle 2003, accompanied by an emended reconstruction. This morphological feature of so basal a species informs further phylogenetic studies.