Two new species of dinoflagellate are described from the upper Cenozoic of the North Atlantic region. They are assigned to the goniodomacean genus Capisocysta Warny and Wrenn, 1997 emend., whose archeopyle uniquely forms by the extensive and exclusive dissociation of hypocystal plates. Capisocysta lata new species is recorded from the upper lower Pliocene Coralline Crag Formation of eastern England, the lower and upper Pliocene of the subsurface Great Bahama Bank, and as a living cyst from Phosphorescence Bay, Puerto Rico. Capisocysta lyellii new species is reported from the Coralline Crag Formation of eastern England. Capisocysta provides the only unambiguous example of a hypocystal archeopyle in the order Gonyaulacales and the only example of a hypotractal archeopyle in the division Dinoflagellata.

The spherical, proximate cysts have pre-formed lines of weakness that occur exclusively on the hypocyst, where they follow plate boundaries. Upon excystment, these sutures facilitate the separate release of plates 2–6″′, ps, 1p, and 1″″. Sulcal plates 1s and rs and postcingular plate 1″′ typically remain attached to the epicyst, forming a distinctive hyposulcal tab. The single antapical plate in C. lata is represented in C. lyellii by two plates (left and right first antapical homologues) that are released separately.

Capisocysta has a tropical to warm temperate distribution today. It thrived and perhaps formed blooms in tropical carbonate platform environments of the Bahamas during the Pliocene, and might prove to be a useful indicator of very warm intervals within the Pliocene of higher latitude regions including the southern North Sea basin.

To facilitate discussion of Capisocysta, several morphological terms have been modified or newly introduced. These terms more precisely describe archeopyle position and extent in dinoflagellates.

Relative differences between environmentally controlled variation and genetically controlled variation are important when investigating morphologic variation in general, especially when establishing species concepts. The colonial nature of bryozoans provides a means for distinguishing between the two sources; variation can be partitioned into within-colony (microenvironmental) and among-colony (environmental + genetic) components. For the Paleozoic order Cryptostomata, biologically and taxonomically significant morphologic characters are well defined and methods for recognizing morphotaxa are well established.

The importance of within-colony variation to the morphometric treatment of fenestrate species was assessed after the discovery of a large specimen of Hemitrypa sp. Variation within the colony was compared to variation among and within two congeneric species. The distribution of study segments across the colony allowed assessment of variation both along the growth axis and laterally between segments of approximately equivalent generational age. Repeatability of methods was assessed using data measured independently from identical segments by three workers.

Variation within the large colony is less than variation among congeneric species, indicating that genetic differences among species exceed variation resulting from combined phenotypic and genotypic sources within species. Neither astogenetic nor ontogenetic morphologic gradients are recognized. Variation between data collected from identical segments by pairs of workers falls within the range of variation for the entire colony. Thus, multiple workers can reproduce data to the finest level of meaningful resolution. Cryptostome morphospecies concepts are validated.

The potential for partitioning genotypic versus environmental variation in reduced, multidimensional morphospace is reinforced. Studies of microevolution and speciation may be designed that account for these factors.

Structures that mimic the general shape of cheilostome avicularia occur within the Paleozoic fenestrate bryozoan genus Fenestrapora. These structures, here termed aviculomorphs, are isolated within laminar extrazooidal skeleton and are characterized by an elongate triangular outline that surrounds a shallow, concave pit. The acute tip of the triangular structure was elevated above the general level of the surrounding skeleton, as is the case for many avicularia. The aviculomorphs could not have functioned precisely as do avicularia, but like avicularia they are inferred to have had a thickened cuticular mandible that matched the skeletal base and to have been able to articulate the mandible open and closed along a fulcrum on the short side of the triangular skeletal outline.

Phylogenetic relationships among higher taxa of articulate brachiopods that developed a spiralium as mineralized support for the lophophore, and the resulting classifications, are not universally agreed upon due to the complex pattern of character evolution within the phylum. Our results, using phylogenetic methodology in conjunction with traditional methods, showed a more complete and easily testable picture of this evolution than either method used alone. A detailed working hypothesis of athyridide phylogeny and the supporting evidence on character distribution is given, and a new classification of the impunctate and punctate athyrids sensu lato is presented with diagnoses to subfamily. Agreement between the stratigraphical first appearance of athyridid subfamilies and their cladistic rank was quite good (except for the koninckinoids), suggesting that both outgroup and traditional paleontological methods indicate a similar direction of character polarity in the evolution of the group. The classification is proposed based on a mix of external and internal characters which persisted during unbroken lineages. New taxa are the families Parazygidae and Triathyrididae; the subfamilies Whitfieldellinae, Triathyridinae, Septathyridinae, Cleiothyridininae, Ochotathyridinae and Plectospirinae, and the genera Brimethyris, Carteridina, Tetraloba and Cooperispira. We studied the great morphological diversity among the athyridids. Their complete stratigraphical ranges help in building phyletic lineages.

Analysis of previously unstudied shell characters reveals the existence of three new genera of Cenozoic muricid neogastropods. These are the new genera Muregina (type species: Murex lugubris Broderip, 1833; ?early Miocene, Pliocene to Recent, eastern tropical Pacific); Kestocenebra (type species: Murex curvicosta Grateloup, 1840; early to late Miocene, Europe); and Edithais (type species: Concholepas drezi Vokes, 1972; early to late Miocene, circumtropical).

A review of muricids with a labral tooth (a ventrally directed projection on the outer lip) shows that this structure forms in several distinct ways. It may form at the end of an external groove (as in Muregina) or cord (as in Kestocenebra), grow continuously or discontinuously, and lie at positions ranging from the upper end of the siphonal canal to just below the middle of the outer lip. The labral tooth evidently evolved independently several times, often quite recently in genera such as Muregina, in which older representatives lack a labral tooth.

Thirty-four species of trilobites belonging to 21 genera are recognized in the Albertella Biozone within the Grassy Spring Member (new name) of the Pioche Shale of southeastern Nevada. Genera include Pagetia, Poliella, Kootenia, Olenoides, Albertella, Albertellina, Albertelloides, Delamarella, Mexicaspis, Paralbertella, Ptarmiganoides, Ursinella, Zacanthoides?, Amecephalites, Mexicella, Nyella, Onchocephalites?, Pachyaspis, Panacus, Plagiura, and Volocephalina. Two new corynexochid genera and species, Delamarella brevispinaspis and Ursinella major, are described. The existing corynexochid genus Albertella is revised to include two new species, A. fritzi and A. highlandensis. A new species, Albertelloides kitai, is described. Two new ptychopariid genera, Amecephalites and Panacus, plus four new ptychopariid species, Amecephalites sundbergi, Mexicella granulata, Panacus palmeri, and Volocephalina variosa, are described and Nyella immoderata Palmer is revised. In addition, the Albertella Biozone is divided into three new subbiozones, the lower Albertellina aspinosa Subbiozone, the middle unnamed subbiozone, and the Albertella highlandensis Subbiozone.

Superbly preserved specimens of Eucalyptocrinites tuberculatus from the Waldron Shale (Silurian, Wenlockian) of Indiana have been found with epibionts attached in living position to their stems. The rhynchonellid brachiopod Stegerhynchus indianense, the tabulate coral Favosites forbesi, the annelids? Spirorbis and Cornulites, bryozoans, and rarely the ichnogenus Tremichnus utilized living crinoids as secondary tiering surfaces. Crinozoans also attached to upright crinoid columns, and their holdfasts are the most abundant epibionts on pluricolumnals. Eucalyptocrinites crassus individuals contributed to the success of their epibionts by providing stable attachment surfaces elevated up to one meter above the sediment-water interface. Although crinoid-epibiont relationships are frequently blurred by taphonomic processes, articulated crinoid specimens and encrusters on pluricolumnals suggest that secondary tiering was a significant paleoecological element in the Waldron Shale.

An exceptionally large skeleton of Pentaceratops sternbergi (Ornithischia:Ceratopsia) provides for the first time an accurate impression of the body proportions in this horned dinosaur. This is the only known specimen with a skull associated with most of the postcranial skeleton. The restored skull is nearly three meters in length and is thus the largest of any ceratopsian and the largest skull thus far known in any terrestrial vertebrate. The elongate rostrum, elaborate premaxillary structure, and complex frontal and cornual sinuses demonstrate a high level of intraspecific variability in these features. Such features are therefore likely not useful in providing species-level discrimination in other chasmosaurines. The function of the intricate chasmosaurine premaxillary narial structures is probably associated with an advanced level of herbivory.

A shallow-marine fossil biota was recovered from the Blue Bluff unit (formerly part of the McBean Formation) in the Upper Coastal Plain of eastern Georgia. Biochronologically significant mollusks (e.g., Turritella nasuta, Cubitostrea sellaeformis, Pteropsella lapidosa) and calcareous nannoplankton (e.g., Chiasmolithus solitus, Reticulofenestra umbilica, Cribocentrum reticulatum) indicate a latest Lutetian-earliest Bartonian age, or about 40 to 41 Ma. Georgiacetus vogtlensis new genus and species is described from a well-preserved, partial skeleton. Georgiacetus is the oldest known whale with a true pterygoid sinus fossa in its basicranium and a pelvis that did not articulate directly with the sacral vertebrae, two features whose acquisitions were important steps toward adaptation to a fully marine existence. The posterior four cheek teeth of G. vogtlensis form a series of carnassial-like shearing blades. These teeth also bear small, blunt accessory cusps, which are regarded as being homologous with the larger, sharper accessory cusps of basilosaurid cheek teeth.

Storeacolumnella hudsonensis is described as a new genus and species of encrusting, colonial organism that lived in an intertidal, rocky-shore environment. The fossil was discovered in the basal beds of the Upper Ordovician Port Nelson Formation at a coastal outcrop on Hudson Bay near Churchill, Manitoba. Showing some possible characteristics of sponges and other possible characteristics of calcaerous green algae, this matlike organism is considered nonetheless to have uncertain taxonomic affinities. It consists of cylinder-shaped columns, each with an internal system of star-shaped filaments or spicules as viewed in transverse section. The cylinders stand vertical in longitudinal section and are densely packed together to form a mat. The hard substrate to which the mat is attached consists of a boulder eroded from the Precambrian Churchill Quartzite. Maximum colony size observed in a single example exhibits a diameter of not less than 80 mm and maximum thickness of 5.85 mm.

The siphonophrentidae is a family of Devonian rugose corals that are known mostly from eastern North America, a part of the Eastern Americas biogeographical Realm (EAR) during the Devonian. Breviphrentis Stumm, 1949, has been considered a siphonophrentid by most previous authors and, in a recent monograph (Oliver, 1993), I described three EAR species as Breviphrentis and referred others to the genus.

Shi and Waterhouse (1996, p. 127) proposed a new genus, Yukonella, for a distinctive licharewiinid species (Spiriferida, Brachiopoda) based on well-preserved material from the Lower Permian upper Jungle Creek Formation, northern Yukon Territory, Canada. However, the Editor of the Zoological Record, Mrs. M. Joan Thorne (personal commun., 1997), has kindly informed me that the name Yukonella is preoccupied by an Upper Triassic poriferan genus published by Senowbari-Daryan and Reid (1986, p. 900). I therefore rename the brachiopod genus Nahoniella after the Nahoni Range in the northern Ogilvie Mountains of northern Yukon Territory, Canada, where the type species of the genus, Nahoniella plana (Shi and Waterhouse), was collected.

In 1992 Sander described in this journal a find of the ichthyosaurian genus Cymbospondylus from the Middle Triassic of Spitsbergen. At the time of publication, the specimen illustrated in figures 2-4 (Sander, 1992) and five associated elements (not figured) were housed at the Paleontological Institute and Museum of the University of Zürich (PIMUZ A/III 496 and PIMUZ A/III 647-651). These specimens were later donated by their collector and owner Professor Hans-Joachim Schweitzer (Bonn) to the Paleontological Museum of the University of Oslo (PMO), where they are now stored under the following numbers:

• PMO 162.003 (=PIMUZ A/III 496, figs. 2-4 in Sander, 1992)

• PMO 162.004 (=PIMUZ A/III 647)

• PMO 162.005 (=PIMUZ A/III 648)

• PMO 162.006 (=PIMUZ A/III 649)

• PMO 162.007 (=PIMUZ A/III 650)

• PMO 162.008 (=PIMUZ A/III 651)