The St. George Group in western Newfoundland is nearly 600 m thick and is subdivided into the Watts Bight, Boat Harbour, Catoche, and Aguathuna Formations. The group is a nearly complete Lower Ordovician succession representing about 15–20 m.y. The depositional environment of the St. George Group is represented by three main lithofacies (supratidal, peritidal, and subtidal), expressed as two first-order cycles and five second-order cycles.

In the study of St. George Group conodonts, over 70 multielement species are represented in 45,000 conodont specimens from 432 samples of 10 sections. Computer cluster analysis of most of those samples on the basis of similarity of conodont species was used to determine conodont community structure. Both the principal coordinate analysis (PCA) partitioning method and the agglomerative method (UPGMA with Bray-Curtis) were chosen for the statistical analysis. The four lithological formations and five secondary lithological cycles in the St. George Group emerge as distinct entities when the samples are clustered together on the basis of conodont data for analysis of first-order and second-order variations in community composition.

Two deeper water, five shallow-water, and five intermediate communities through this time interval are recognized. The majority of conodonts from these communities are of Midcontinent Realm affinities, but some species represent strong North Atlantic Realm influxes during the transgressive periods.

Eosuchus minor (Marsh, 1870) is based on skeletal fragments from the Late Paleocene or Early Eocene of New Jersey, but more complete material from the Late Paleocene of New Jersey, Maryland, and Virginia permits a detailed description and systematic assessment. It is a slender-snouted form and can be distinguished from most other crocodylians on the basis of an enlarged quadrate foramen aereum; a distinct W-shaped rugosity along the ventral margin of the basioccipital tuber; a prominent crest on the lateral braincase wall encompassing portions of the quadrate, pterygoid, and basisphenoid, forming the lateral wall of the lateral eustachian canal at its ventralmost extent; and arrangement of dentary alveoli into couplets. Specimens of larger crocodylians from the same units may represent either the adult form of E. minor or a separate taxon. The enlarged quadrate foramen aereum, couplet arrangement of dentary alveoli, and basioccipital tuber shape are shared with Eosuchus lerichei from the Late Paleocene of Europe. Eosuchus lies within Gavialoidea crownward of the basal forms Thoracosaurus and Eothoracosaurus. The braincase of Eosuchus is intermediate between that of Thoracosaurus and that of Gavialis; the basisphenoid retains a short (but externally visible) descending lamina, but the basisphenoid is also anteroposteriorly expanded at the level of the median eustachian foramen.

The early Miocene Durudawiri inusitatus new genus and species (Marsupialia: Phalangeroidea) is described from the Riversleigh World Heritage Property in northwestern Queensland. It appears to represent the plesiomorphic sister group of the late Oligocene species of Miralina from South Australia. Its molar morphology is not as complex as that of species of Miralina or ektopodontids, but it is more complex than that of phalangerids. The degree of morphological difference between species of Durudawiri and Miralina suggests subfamilial distinction for the two groups. Strange cusps on the upper molars could be interpreted as either large neometaconules and paraconules, or lingually-displaced metacones and paracones with very large stylar cusps on the buccal shelf.

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 visceral skeleton (including complete mandibular, hyoid, and branchial arches) and teeth of the Lower Cretaceous hybodontid shark Tribodus limae are described based on well preserved fossil material. Jaw suspension and musculature are reconstructed, representing the first reconstruction of jaw musculature in a hybodont. The jaw suspension of Tribodus is similar to batoids and advanced galeomorphs in lacking direct cranio–palatine articulations and having skeletal jaw support by the hyoid arch alone (unlike most other hybodonts), but differs from batoids in that an intact hyoid arch is present. As in Asteracanthus and Lonchidion, the jaws do not extend to the snout, and were connected symphysially but not fused. CT scanning reveals the presence of supportive ‘trabecular cartilage’ struts in force-bearing regions of the jaws, representing the first report of these structures in an extinct chondrichthyan. Five branchial arches are present, of which pharyngobranchial, epibranchial, and ceratobranchial elements are observed although hypobranchials and basibranchials were presumably also present. A pharyngobranchial blade is present, as in some other hybodonts (e.g., Lissodus) and extant galeomorphs (e.g., Heterodontus), and the posteriormost pharyngobranchials are unfused. Tribodus is considered durophagous, based on presence of ‘trabecular cartilage’ struts and a weakly heterodont monognathic pavement dentition of flattened hexagonal teeth, as in extant myliobatoid rays. SEM examination shows that teeth of T. limae are anaulacorhize with a double layer of single crystallite enameloid (SCE), and confirms the presence of columnar osteodentine, as in other Acrodontidae.

The late Miocene Gatun Formation of northern Panama contains a highly diverse and well sampled fossil marine assemblage that occupied a shallow-water embayment close to a purported connection between the Pacific and Atlantic (Caribbean) oceans. However, the diverse chondrichthyan fauna has been poorly documented. Based on recent field discoveries and further analysis of existing collections, the chondrichthyan fauna from this unit comprises at least 26 taxa, of which four species are extinct today. The remaining portion of the total chondrichthyan biodiversity has affinities with modern taxa and is therefore comprised of long-lived species. Based on known records of the modern geographic distribution range of the Gatun chondrichthyans, the fauna has mixed biogeographic affinities suggesting that around 10 million yr ago, a connection likely occurred between the Pacific Ocean and the Caribbean Sea. Given the known habitat preferences for modern chondrichthyans, the Gatun fauna was primarily adapted to shallow waters within the neritic zone. Finally, comparisons of Gatun dental measurements with other faunas suggest that many of the taxa have an abundance of small individuals, in agreement with previous studies that proposed this area as a paleonursery habitat for the species Carcharocles megalodon.

Echinoid fragments were reported by Zachos (1990) from a Weches Formation (Clairborne) outcrop on Hooker Creek in Burleson County, Texas. Enough fragments have been found at the latter locality to piece together a composite identifiable as a species of the spatangid genus Maretia, most likely M. arguta. This species has not previously been reported outside of Clarke County, Mississippi. A search of the stratigraphic collections of the Texas Memorial Museum in Austin, Texas, has uncovered several previously unidentified specimens of M. arguta from two Weches localities, at Kickapoo Shoals on the Trinity River in Houston County and at Nacogdoches in Nacogdoches County. In addition, spatangoid fragments, some of which are attributable to M. arguta, are common in collections from the Weches and Cook Mountain Formations.

A low-diversity crinoid fauna is described from the Fitchville Formation, Lower Mississippian (Late Devonian to Early Mississippian) of Utah County, Utah. Based on the crinoid fauna, composed of Nunnacrinus olsoni new species, Paracosmetocrinus lundi new species, and Platycrinites sp., this fauna is interpreted as being from the Kinderhookian, Upper Fitchville Formation. This occurrence of Nunnacrinus extends the geographic and facies range of this genus in western North America and the geographic range of Paracosmetocrinus within western North America.

Fossiliferous marine Devonian has been known in Chile for less than a decade. The initial discovery from south of the Salar de Atacama region, in the Sierra de Almeida, northern Chile is described together with its brachiopods. The brachiopods indicate an age span of Emsian–Eifelian or Givetian, shallow-water conditions in the Benthic Assemblage 2 range, and a biogeographic boundary region between the cool climate Malvinokaffric Realm and warmer region extra-Malvinokaffric Realms, including the Eastern Americas Realm and the Rhenish-Bohemian Region of the Old World Realm. The recent discovery of a Malvinokaffric Realm trilobite far to the south in Chile, at Buill in the Andes of Chiloe, serves to underline our very preliminary knowledge of the Chilean Devonian, whereas the alleged Devonian brachiopods from the Chonos Archipelago far to the south are probably bivalves of uncertain age.

Neoplagiaulacid multituberculates are among the most numerous and best represented members of early Cenozoic North American mammal faunas, achieving their greatest diversity during the Paleocene. Despite their relatively dense record in the Torrejonian (middle Paleocene) and Tiffanian (late Paleocene), the study of early Cenozoic neoplagiaulacids has been limited more often than not to isolated teeth or, more rarely, incomplete skull, gnathic, or postcranial remains. The current study reports on new neoplagiaulacid multituberculates from the Paleocene Paskapoo Formation of central Alberta, Canada, at localities along the Blindman River near the City of Red Deer. The exceptionally well-preserved specimens consist of incomplete articulated and associated skull and gnathic remains, and collectively document four new species: Ectypodus elaphus, Neoplagiaulax serrator, Neoplagiaulax paskapooensis, and Neoplagiaulax cimolodontoides. Neoplagiaulax paskapooensis is the most dentally complete neoplagiaulacid so far discovered, with a single specimen documenting for the first time left and right I2 and I3 in situ with the cheek teeth, along with the associated lower dentition. Specimens of Neoplagiaulax cimolodontoides record important details of the rostrum and palate, and provide the first direct evidence of incisor replacement in Neoplagiaulax. The new neoplagiaulacids, together with other multituberculates from the Blindman River localities, document unusually high multituberculate diversity in the latter half of the Tiffanian in western Canada. Despite superficial similarity to some European species of Neoplagiaulax, the new taxa from the Paskapoo Formation apparently show no closer relationship to these than do other North American congeners, suggesting parallel evolution in endemic North America and western European clades.

Abundant, well-preserved specimens of a new peltocystidan mitrate carpoid, Jaekelocarpus oklahomensis n. gen. and sp., have been discovered in the Pennsylvanian (Morrowan Series) Gene Autry Shale Member, Golf Course Formation, in southern Oklahoma. The new carpoid postdates the youngest previously known carpoids (Middle Devonian) by about 65 million years. It is characterized by a small (to 4 mm in length) globose theca composed of six plates: two large adaulacophorals, two large marginals, and two relatively small plates that frame the main thecal orifice. One of the plates at the orifice bears a single stout spine. The theca and plates that comprise the theca display a high degree of bilateral symmetry. In contrast, the styloid has an asymmetrical array of spines and blades.

We hypothesize that most mitrates, including this one, were adapted to an infaunal life mode. The streamlined, generally symmetrical body shape is an adaptation to moving on or through the substrate. Spines and blades on the lower surface of the styloid and proximal aulacophore are inferred to be adaptations for gripping the substrate as the animal pulled itself backwards (aulacophore first). The main thecal orifice opposite the aulacophore was the site of both mouth and anus. Evidence for a sluggish, epifaunal life mode in the cornute carpoids includes the typically flattened, asymmetrical body, the presence of downward projecting spines and knobs on the marginal thecal plates of many species, and the specialized thecal pores and slits that faced away from the substrate.

A new, flattened, eocrinoid-grade, blastozoan echinoderm Haimacystis rozhnovi new genus and species is described from the uppermost Lower Ordovician Wah Wah Limestone of western Utah. Although apparently most similar in morphology to the rhipidocystids, Haimacystis differs in its plane of thecal flattening, lack of one-piece marginals, and ambulacral system development. A comparison of overall morphology and plane of thecal flattening is presented for flattened blastozoans. Haimacystis was a streamlined suspension feeder attached to the sea floor by a holdfast at the end of a relatively short stem and bent over in the water column in moderate currents.

Purgatorius titusi, represented by 51 teeth and jaw fragments, is described from the lower Paleocene Bear Formation of the Crazy Mountains Basin in south-central Montana. Several synapomorphies, including a weak postprotocingulum and mesial inflection of molar trigonids, are indicative of the taxon's “plesiadapiform” affinities. Other features, such as wider stylar shelf and a less squared lingual outline on upper molars, are more primitive than those of Purgatorius unio, heretofore the earliest occurring species of well-represented primatomorphs.

The discovery of a new naraoiid nektaspid in the Upper Silurian (Pridolian) of southeastern Ontario significantly extends the range of this unusual group. Nektaspids are nonmineralized arthropods typical of Early and Middle Cambrian soft-bottom communities, but were thought to have become extinct in the Late Ordovician. The unique holotype specimen of Naraoia bertiensis n. sp. comes from a Konservat–Lagerstätte deposit renowned for its eurypterid fauna (the Williamsville Member of the Bertie Formation). Naraoia bertiensis lacks thoracic segments and is morphologically similar to Naraoia compacta from the Middle Cambrian Burgess Shale, save for the presence of a long ventral cephalic doublure and a subtly pointed posterior shield. To examine the phylogenetic relationships of the new naraoiid, we coded characters of the holotype specimen and of nine previously described nektaspids. The results confirm a sister taxon relationship between Naraoia compacta and Naraoia bertiensis and the monophyly of nektaspid forms lacking thoracic segments (family Naraoiidae). This latter group may have arisen from an ancestral segment-bearing form through heterochronic loss of thoracic segments early in the Cambrian. The disjunct occurrence of a naraoiid nektaspid in the Late Silurian resembles the reappearance of other “Lazarus taxa” that were thought to have been eliminated during mass extinction events. The naraoiid lineage survived the Late Ordovician biotic crisis, but in this case the “Lazarus effect” seems likely to be taphonomic in origin.

An enteletid brachiopod genus Peltichia Jin and Liao, 1981, is reviewed and emended based on specimens from the Permian sequences of Japan, South China, Vietnam, and Transcaucasia. New and revised taxa are Peltichia akasakensis (Ozawa), P. kwangtungensis (Zhan), P. ruzhencevi (Sokolskaja), P. sinensis (Huang), P. subtriangularis new species, P. transversus (Huang), and P. zigzag (Huang). The genus Peltichia, consisting of 10 species, ranges from Kungurian to Changhsingian, and is distributed geographically in the Tethyan Realm and its surrounding areas and probably as well as in the western Panthalassan region.

The species Pleurostomella concava is a new benthic foraminifer recognized in Oligocene and Miocene sediments from the Indian and Pacific Oceans. The first mentioned finding of this species is in the material recovered from the experimental Mohole drilling near Guadalupe Island off Baja California. The morphology of Pleurostomella concava differs distinctively from other species of the genus Pleurostomella by its concave apertural face and keel-like rim around the ultimate chamber.