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.

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.

The skeleton of a newly discovered, exceptionally preserved specimen of Saniwa ensidens is described in detail. The fossil consists of a complete articulated skeleton exposed in dorsal view. It adds important additional information to our knowledge of the anatomy of this fossil varanoid taxon, including a detailed description of the dermatocranium in dorsal view, complete vertebral counts, and a detailed account of the appendicular skeleton. Cartilage preservation allows the identification of treacheal rings, sternum, inscriptional ribs, epicoracoid and suprascapula. Patches of skin are preserved on dermal skull bones, and scattered scales surround the entire skeleton. Incomplete ossification of carpal and tarsal elements, as well as of epiphyses, indicate that the specimen is not fully mature.

Epipunctae, a new type of shell perforation, are well developed in typical taxa of the family Plaesiomyidae, a group of common orthide brachiopods from Laurentia and some other tropically located tectonic plates of Late Ordovician age. These minute, prominently elongate, tubular structures are similar to endopunctae in size and density, but differ in being oblique, intersecting the shell surface at a relatively low angle, and being confined largely to the outer portion of the shell wall. The tubules are similar in orientation to aditicules within the same shells but are much smaller and denser, usually aligned along fine growth lines and arranged in crude longitudinal columns. Exceptionally preserved phosphatic molds of bundled setal canals inside epipunctae and aditicules, described for the first time in this paper, are direct evidence that these two types of tubular structures of different sizes had the same function of housing sensory setae along the shell margin, but both the setae and the tubules became abandoned in the outer portion of the shell wall through burial by the secondary shell layer when the shell margin migrated forward. Epipunctae have been found so far only in plaesiomyid shells, but aditicules are common in many groups of the order Orthida. The taxonomic value of epipunctae is shown by a reassessment of PionorthisSchuchert and Cooper, 1932. The hypotype previously regarded widely, but erroneously, as the archetype of ‘Orthis sola’ Billings, 1866, the type species of Pionorthis, is allied to PlaesiomysHall and Clarke, 1892. It bears the characteristic epipunctae. The holotype of Orthis sola is a dalmanelloid shell with true punctae, assignable to MendacellaCooper, 1930. This warrants rejection of the genus Pionorthis.

The recovery of well-preserved silicified immature exuviae allows the first description of the early ontogeny of the phacopid Nephranops incisus incisus from the lower Famennian of Thuringia (central Germany). Evidence is presented that both planktonic and benthic protaspid larval stages were present in phacopid trilobites. Ontogenetic meraspid changes of this species are similar to those of Weyerites and Phacops, supporting the close phyletic relationships between these genera and the ontogenetic homogeneity of the Phacopidae.

Description of two new species of macruran decapod crustaceans, Hoploparia uzbekensis and Linuparus dzheirantuiensis, from Late Cretaceous rocks in the Kyzylkum Desert, Uzbekistan, represents the first published record of decapods from that country. Hoploparia is considered to be an intact, integrated genus. Specimens of Hoploparia uzbekensis and Linuparus dzheirantuiensis collected from the Aitym and Bissekty formations, respectively, are preserved as altered cuticular material in a sandy matrix. Specimens of Hoploparia and Linuparus collected from the Uchkuduk and Dzheirantui formations, respectively, are preserved as ironstone replacements, an unusual preservation style for decapods. The cephalothorax on the specimen of Linuparus from the Dzheirantui Formation has been partially broken in a manner suggestive of predation. The lateral thoracic flanks of the holotype of Linuparus dzheirantuiensis bear a raised, ridged area suggestive of a stridulating structure. These genera, although cosmopolitan in the Cretaceous fossil record, have not been recognized previously in central Asia.

New material from the Late Mississippian Fayetteville and Caney Formations of the south-central USA supports the taxonomic revision of the Mississippian actinoceroid cephalopods. New representatives of the previously poorly known Rayonnoceras solidiforme, Campyloceras striatulum, and Campyloceras imoense are described. Carbactinoceras procerum new species and Elmoceras graffhami new genus and species are described, and the genus Campyloceras is emended. Character evaluation suggests the shape of the endosiphuncular deposits in the Actinoceratida and Pseudactinocerida are homoplastic because similar patterns of endosiphuncular deposits occur in distantly related nautiloid clades. Apex shape, however, is shown to have previously unrecognized potential for taxon discrimination. Cladistic analysis of 13 actinoceroid and pseudorthocerid nautiloids supports the splitting of the Orthocerida and the creation of a sister group to the Actinoceratida which is identical with the largely neglected Pseudorthocerida.

Pterygotus monroensis from the Pittsford and Harris Hill members of the Silurian Vernon Formation, New York State, USA, is here assigned to Erettopterus osiliensis, previously known only from Saaremaa, Estonia, based on new material (carapaces, chelicerae, a prosomal appendage VI, several metastoma, genital opercula with appendages, an almost complete opisthosoma, and several bilobed telsons), and re-examination of the original specimens. Telson morphology indicates assignment to Erettopterus or Truncatiramus, but the differences between these two genera are here interpreted as insignificant, and all species are treated as belonging to Erettopterus. The much rarer Pterygotus? sarlei n. sp., a possibly basal pterygotid, also from the Pittsford Member, is based on two telsons with pterygotid-like marginal cuticular sculpture. The telson shape is unlike that of any other adult pterygotid; it is relatively similar to juvenile pterygotids and Slimonia, but lacks the long posterior spine found in Slimonia. These systematic revisions have implications for other pterygotid taxa. Pterygotus impacatus, from Estonia, is a junior synonym of E. osiliensis. P. waylandsmithi, from slightly higher in the Vernon Formation, and is transferred to Erettopterus based on similarities of the chelicerae to E. osiliensis.

Six stratigraphically distinct trilobite faunas are recognized in the Lower Mississippian strata of the central United States. These faunas range in age from earliest Kinderhookian to Meramecian, and are, in ascending order: Pudoproetus missouriensis, Comptonaspis swallowi, Proetides insignis-Perexigupyge, Breviphillipsia semiteretis, Exochops portlockii, and Hesslerides bufo. Trilobite species diversity waxed and waned through the early Mississippian of the central United States, but reached its maximum during the late Kinderhookian within the Comptonaspis swallowi fauna. The Comptonaspis swallowi, Breviphillipsia semiteretis, and Exochops portlockii faunas of the mid-continent can be correlated with the C. swallowi, B. semiteretis, and Hesslerides arcentensis faunas of the Caballero and Lake Valley Formations of New Mexico. The vertical distribution, composition, and diversity variations among individual faunas suggest that they are evolutionarily discrete and therefore of biostratigraphic utility. Their stratigraphic distribution appears to be controlled by sea level and climatic fluctuations.

A new genus and species of turrid neogastropod, Kyllinia parentalis, is described based on three shells from the Pliocene (North Italy) and the Pleistocene (northwestern Peloponnesus) of the central Mediterranean area. The new taxon is compared to the buccinid (sensu lato) genus MetulaH. and A. Adams, 1853 with which it shows a few superficial similarities mainly limited to the latticed sculptural pattern of the teleoconch. Kyllinia parentalis is placed in the turrid subfamily Mangeliinae on the basis of teleoconch characters (double sinuosity of the outer lip and the short, forward curved anterior canal) and protoconch (a characteristic pattern formed by narrow axial riblets giving a coronated suture to the larval shell). These taxonomic characters, together with the almost clathrate teleoconch sculpture, form an original combination within the Mangeliinae, thus justifying the description of a new genus. The Recent species Philbertia marchadiKnudsen, 1956 (for which we consider the previous attributions to PhilbertiaMonterosato, 1884 and Diaugasma, Melvill, 1917 incorrect) from the Republic of Guinea and Angola closely resembles K. parentalis, but differs in having axial folds on early teleoconch whorls, a more slender shell, and a proportionally taller last whorl. Philbertia marchadi fits well with the characteristics of the herein described genus, so that we propose the new combination Kyllinia marchadi (Knudsen, 1956). Kyllinia parentalis, a species originated in the Mediterranean Pliocene, is to be considered as the ancestor of K. marchadi. Kyllinia parentalis should be regarded as a meaningful marker in recognizing warm Mediterranean Pleistocene events.

The tricranocladine sponges (now assigned to the suborder Eutaxicladina) are a conservative group consisting of the single family Hindiidae. The genus Hindia Duncan is considered the base of the tricranoclad evolutionary record. A new sponge discovered from the Ordovician limestones of the San Juan Formation in the Argentine Precordillera allows a reexamination of the Hindiid lineage and extends the early history of the tricranocladines back to the Darriwilian. Eoscheiella concava n. gen. and sp. is described and illustrated. It is known from a single chertified, spherical specimen with a central hollow core, a typical character found in several genera of the family. Tricranoclads, megarhizoclones, and radial monaxonic spicules are the main skeletal components of the new genus. The presence of a band of subparalell tangential monaxons on the surface of Eoscheiella can be related to an inferred, small, root tuft that attached the spherical sponge to the substrate. The discovery of Eoscheiella modifies the evolutionary view of the family, for it is the oldest genus now known with simple dipodal and tripodal tricranoclads without a brachyome, radial monaxons, and megarhizoclones. Eoscheiella displaces the genus Hindia from the base of tricranocladine evolutionary history. Variability in spicule form, arrangement, and clasping possibilities observed in Permian representatives are clearly more accentuated in the Ordovician Eoscheiella. All these features appeared earlier than expected in previously proposed evolutionary trends.

Eosaniwa koehni is an enigmatic platynotan that differs from related varanoids in the possession of a very long snout resulting in extremely elongate nasals and vomers; a robust and broad jugal; the presence of denticles on palatines, pterygoids, and vomers; the presence of a subdental shelf on the dentary; and a strongly twisted retroarticular process on the mandible. Phylogenetic analysis suggests that Eosaniwa is a derived varanoid platynotan, nested within a clade also including mosasauroids, Coniasaurus, and Paravaranus.

We establish a new genus of a hyaenaelurine hyaenodontid (Creodonta: Mammalia), Orienspterodon for “Pterodon” dahkoensis, which is known from three late middle Eocene localities in central and southern China and Myanmar. This paper provides a full description of the species and a comment on the early evolution of Hyaenaelurinae. Some features of Orienspterodon (p2–p3 without an anterior accessory cuspulid, lesser reduction of the m3 talonid relative to m1–m2 talonids, double-rooted P3, and better fusion of the paracone and metacone on M1) confirm that O. dahkoensis is distinct from Pterodon. Orienspterodon differs from the other specialized hyaenodontids from the Paleogene of Asia in being a hyaenaelurine, in being unrelated to Hyaenodon, and in having a geographical distribution in the southern part of the continent. Orienspterodon represents the earliest fossil records of Hyaenaelurinae, and some features (small metaconid on m3, basined talonid on all lower molars, a short and more diagonally oriented metastyle, large size, better fused paracone and metacone) indicate an early branching of this genus from the other hyaenaelurines.

Two specimens of the cornute Phyllocystis crassimarginataThoral, 1935 from the Lower Ordovician of Southern Montagne Noire (Languedoc, France) showing abnormal numbers of marginal plates are described. The first one (UM 310) is characterized by the insertion of one extra plate between the fourth right marginal and the zygal plate Z. Comparison with a new, undescribed Tremadoc boot-shaped cornute suggests that 1) the extra plate of UM 310 is equivalent to M4, and 2) the three right marginals located between M1 and Z in “normal” specimens of Phyllocystis can be identified as M2, Mc, and M3. Plate configurations of the right thecal margin are thus identical in “normal” Phyllocystis, chauvelicystids, and cothurnocystids. This result indicates that Phyllocystis is probably more closely related to these two clades than to scotiaecystids. Consequently, the identification of the four marginals forming the left thecal margin of Phyllocystis (M′2, M′3, M′5, and M5) is deduced from a comparison with the cothurnocystid plate pattern. The second abnormal specimen of P. crassimarginata (R64546) is characterized by the loss of M′3. It confirms that reduction in the number of marginals is a general trend in boot-shaped cornutes.