Dimorphosiphon talbotorum n. sp. from the Upper Ordovician Bighorn Dolomite of Wyoming is an ancient representative of the erect skeleton-building green algae. Circumstantial evidence indicates that the original skeletal material was aragonite. If so, D. talbotorum and its Ordovician relatives in eastern North America, Europe, and Kazakhstan are reminders that even morphologically simple aragonite producers could thrive during one of Earth's “calcite sea” intervals.

Unlike previously described Ordovician members of its family, the new species is represented by selectively silicified thalli showing three-dimensional details of internal tubes and a highly variable external form. It differs from a similar taxon, D. rectangulare, in having branched as well as unbranched thalli and in morphology of radial tubes. The new species is the first thoroughly documented record of Dimorphosiphon in western North America. Its stratigraphic position in the Richmondian part of the Bighorn Dolomite correlates with previously reported occurrences of the genus in the Red River Formation of North Dakota and Manitoba.

The Wyoming fossils typically occur as scattered components of wackestone and include both silicified and calcitic individuals. The change in skeletal composition from aragonite to calcite apparently took place before tubes decayed, thus preserving tube morphology. Subsequent silicification varied in degree among specimens, probably reflecting differences in permeability of the secondarily calcitic skeletons.

A delicate and well-preserved latest Permian radiolarian fauna was obtained from muddy siliceous rocks and siliceous mudstones in the Dongpan Section, southwest Guangxi, China. The specimens of family Albaillellidae in the fauna have been selected for taxonomic study in this paper. Two genera and 14 species belonging to this family are recognized and described, including three new species and one new subspecies, namely Neoalbaillella minuta, Albaillella flabellata, Albaillella fida, and Albaillella yaoi longa, respectively. This assemblage is correlated to the Neoalbaillella optima Assemblage Zone. Its biostratigraphic significance and the final extinction of Albaillellidae at the end of Late Permian are observed and discussed herein.

Well-preserved Ordovician conodonts are described from a micritic limestone sequence exposed in the Satun area of southern peninsular Thailand. The faunas represented by these conodonts have North Atlantic Realm affinities and are identical to those reported from North Atlantic Middle to Upper Ordovician successions. Representative conodonts of some of these faunas have also been reported from South China. In ascending order, three conodont zones are discriminated in the Satun sequence: the Pygodus anserinus range Zone, the Baltoniodus sp. cf. B. variabilis range Zone, and the Hamarodus europaeus range Zone. Strata between the B. sp. cf. B. variabilis and H. europaeus zones are not zoned. The conodont-bearing limestone is thought to have been deposited on the continental margin of northeastern Gondwana. Sixteen species belonging to 12 conodont genera, and two unidentified coniform elements, are systematically investigated.

The Lower Cambrian brachiopod Heliomedusa orienta Sun and Hou, 1987a, first identified as a jellyfish, was later described as a craniopsoid brachiopod. A new sample of 1,150 individuals of this brachiopod, measuring 3.1–22.0 mm long, from two new sites of the Lower Cambrian Yuanshan Formation was examined. The sample includes several with exceptional preservation of nonmineralized skeletons that reveal previously unknown features and fill a gap in our knowledge of the detailed anatomy of fossil discinids. It is here reinterpreted as a discinid brachiopod on the basis of its many distinctive, discinid anatomical features, such as a longitudinally oval pedicle foramen in the anterior region of the posterior sector of the ventral valve; inferred, short, but large pedicle descending ventrally from the ventral valve; inferred, paired rectus muscles in the large pedicle canal; elongate scars of paired anterior adductors; and a median septum connected to a U-shaped ridge on the ventral interior. The two growing zones of its exceptionally preserved, unique lophophore extend posteriorly instead of anteriorly as in all Recent inarticulate brachiopods. Its recognition as the first and earliest discinoidean extends its stratigraphic range from the Ordovician to the Lower Cambrian. This reassignment implies that the organophosphatic, pediculate lingulids and discinids evolved before the carbonate, nonpediculate craniopsids and craniids. Its occurrence at chronological proximity to the Cambrian explosion of small metazoans sheds light on the early morphological diversification and the adaptive radiation of the Lower Cambrian brachiopods into the available niches.

The Arco Hills Formation contains abundant lingulate, strophomenate, and rhynchonellate brachiopods, echinoderms, corals, bryozoans, and rare vertebrate and trilobite fossil fragments. Fossils are equally abundant in carbonate and siliciclastic units; however, silicified brachiopods are limited to carbonate lithologies which occasionally have minor amounts of siliciclastic sediment. These silicified brachiopods were extracted for taxonomic, taphonomic, and paleoecologic description. Chesterian brachiopod assemblages of the Cordilleran region are poorly described and this work represents the only systematic treatment of Chesterian macrofossil assemblages in Idaho. Fifteen genera (23 species) of brachiopods are presented from Arco Hills Formation, including two new species: Anthracospirifer arcoensis and Composita idahoensis, described herein.

Giant Middle Coniacian to Lower Campanian Platyceramus Seitz is among the largest Cretaceous bivalves, commonly reaching an axial length of over 1 m, and occasionally over 2–3 m in size. The genus is characterized by its large size, very low convexity, normal inflation limited mostly to the umbonal area, and flattened flanks. It is especially common in moderately deep calcareous shale facies, as well as in chalks and limestones of the Niobrara Formation and equivalents. Preferred facies contain abundant pyrite, elevated total organic carbon (TOC), and very low biotic diversity. The genus maintains its giant size in these facies, and becomes more abundant. It clearly prefers dysoxic facies. As such, it probably is chemosymbiotic; photosymbiosis is almost ruled out because of inferred water depths of 200–350 m. It is also found more sparsely, and of smaller size, in oxygenated facies, including shoreface sandstone. The study area contains over 81 giant-sized Platyceramus platinus (Logan, 1898) on a single bedding plane; there are very few small ones. This allows spacing, orientation, and size analysis to be performed on an adult population.

Fourteen species of Volutidae are recognized from the Neogene of central to southern Chile. Seven species are known from previous descriptions: Voluta triplicata, V. alta, V. domeykoana, V. obesa, V. vidali, Proscaphella taverai, and Adelomelon reconditus. A neotype is designated for Voluta alta. Proscaphella gracilior, type species of the genus Proscaphella, is considered to belong to the genus Miomelon, which places Proscaphella in synonymy with Miomelon. Most species of “Proscaphella,” excluding the type species, form a separate group well distinguished from Miomelon, and for these the new genus Palaeomelon is introduced with Voluta triplicata as type species. Seven new species are reported: Palaeomelon tucapeli, Palaeomelon angoli, Adelomelon colocoloi, Adelomelon caupolicani, Miomelon lautaroi, Miomelon? pelantaroi, and Pachycymbiola? galvarinoi. Voluta triplicata, V. domeykoana, and Proscaphella taverai are included in Palaeomelon n. gen., Voluta obesa and V. alta are referred to Adelomelon, and Voluta vidali is referred to Pachycymbiola. The fossil record of the Recent volute genera Miomelon and Pachycymbiola extends back into the Miocene, Adelomelon is known from the Late Eocene, while Palaeomelon is known in Chile only from the Miocene. Species are morphologically very similar among genera, and from this it is inferred that separation of genera probably occurred in the late Paleogene.

The Platteville crinoid fauna of northeastern Iowa consists of six species: Abludoglyptocrinus charltoni (Kolata, 1975), Carabocrinus sp. Kolata, 1975, Cupulocrinus plattevillensis Kolata, 1975, Ectenocrinus simplex (Hall, 1847), Merocrinus britonensis Kolata, 1975, and Porocrinus pentagonius Meek and Worthen, 1865. Other echinoderms include an unidentified cyclocystoid and several rhombiferan and crinoid plates. The echinoderms are mostly associated with a variety of passive suspension and filter feeders, principally brachiopods and bryozoans. Complete crowns and columns are available for the porocrinid and cupulocrinid, which lived at elevations of 28 and 50–60 mm above the seafloor, respectively. Although entire stems are not preserved, specimens from other stratigraphic units suggest that Abludoglyptocrinus charltoni, Ectenocrinus simplex, and Merocrinus britonensis occupied higher areas above the seafloor. The elevation of the carabocrinid is not known. The cyclocystoid was located on the seafloor. The crinoids are ecologically separated in two ways: different elevations above the substrate and food groove width, which is correlated with the size of the food items taken. The high-level crinoids mainly ate a narrow range of small items. However, the crinoids at lower levels caught many larger food particles and utilized a much wider range of food sizes. Cup growth of Cupulocrinus plattevillensis is isometric except for the heights of the infrabasals and radials, which exhibit significant positive and negative allometry relative to overall size. The proximal brachs are strongly allometric in which the widths increase much more rapidly than the heights.

Trilobites from the Lower Cambrian succession at Angorichina in the eastern Flinders Ranges, South Australia, are described. Silicified material from the Mernmerna Formation reveals the presence of a new assemblage from the Pararaia bunyerooensis Zone, including the eponymous species, Yorkella aff. australis, Eoredlichia sp., Redlichia sp., and the new species Wutingaspis euryoptilos and Yunnanocephalus macromelos. Trilobites of the Pararaia bunyerooensis Zone show a strong affinity with those from the Yu'anshan Member of the Heilinpu Formation in Chengjiang and Jinning Counties, Yunnan Province, southwest China. The Pararaia bunyerooensis Zone is correlated with the Yunnanocephalus Assemblage subzone (upper Eoredlichia–Wutingaspis Zone) of the Chiungchussuan (=Qiongzhusian) Stage of China. Additional trilobites from Angorichina include Elicicola calva from the Wilkawillina Limestone, Estaingia occipitospina (Jell) new combination from the Oraparinna Shale, and Redlichia guizhouensis Zhou from the Wirrealpa Limestone. Australian Early Cambrian trilobite biozonation is reviewed, with discussion of distinct assemblages within the Pararaia janeae Zone that have the potential for zonal subdivision, and evidence to support the placement of the northern Australian Ordian/Early Templetonian Stage within the late Early Cambrian.

A possible paedomorphic lineage between Pararaia bunyerooensis and P. janeae is proposed. Adult specimens of P. janeae retain juvenile characteristics of the progenitor P. bunyerooensis. Retardation in onset of maturity in P. janeae resulted in the attainment of a larger adult size than in P. bunyerooensis, indicating the former species evolved via neoteny.

Sections of fore- and hindlimbs of a Paleozoic sarcopterygian (Eusthenopteron foordi from the Devonian) possess a thin cortical compacta and an extensive and relatively loose medullary spongiosa. Most long bones have no free medullary cavity. The smallest bones appear to have a proportionately thicker cortical compacta (although the trend is not statistically significant) and a free medullary cavity. The morphological synapomorphies of panderichthyids and stegocephalians that could be interpreted as suggesting a life in shallow water and possibly occasional excursions on dry land are absent in E. foordi. Thus, recent data on sarcopterygian morphology are congruent with recent paleoecological interpretations that E. foordi lived in a marginal marine or estuarine environment and had an aquatic lifestyle.

A partial skeleton tentatively referred to the Lower Cretaceous pliosauroid genus Leptocleidus is described from predominantly Aptian (Lower Cretaceous) opal-bearing deposits of the Bulldog Shale near Andamooka in South Australia. Small size coupled with incomplete fusion of the basicranial elements, vertebral centra, neural arches and cervical ribs, and incomplete ossification of the articular surfaces on the propodials and distal limb bones, indicate that the specimen was at an early stage in its ontogeny. Comparison with more mature specimens attributed to Leptocleidus spp. highlights several growth-related differences, particularly a marked disparity in proportions of the humerus and femur relative to the estimated maximum body length. Changes in the cranial skeleton during growth are harder to document because of the fragmentary nature of the skull. Nevertheless, fusion of some cranial sutures and well-developed cranial joint surfaces suggest that extensive ossification may have taken place in parts of the skull during early ontogeny. The potential implications of these findings for feeding, locomotion, and behavior in juvenile plesiosaurs are discussed.

The dyrosaurids of the Iullemmeden Basin (West Africa) are mainly represented by two genera, Hyposaurus and Rhabdognathus. Hyposaurus has been recognized in the Paleocene of Mali and Nigeria with two species, H. nopcsai and H. wilsoni. Diagnostic characters given by previous authors for these species do not enable their distinction from each other, nor from North American species. It is therefore reasonable to consider H. nopcsai and H. wilsoni as nomina dubia. In 1930, Swinton erected the new genus and species Rhabdognathus rarus on the basis of mandibular remains, and Buffetaut referred a skull to this species in 1980. A new skull was described in 2002 by Brochu et al., and referred to Rhabdognathus sp. Unfortunately, it is impossible to refer either skull to the type species, the mandibular remains having no diagnostic characters at the specific level. Thus, R. rarus is a nomen dubium, and two new names are erected for the two skulls: R. keiniensis n. sp. and R. aslerensis n. sp., all the mandibular remains being referred to Rhabdognathus sp. The species Rhabdognathus compressus is reassigned to the genus Congosaurus, since its mandible is higher than that of Hyposaurus, shorter than that of Rhabdognathus, and the lateromedially compressed teeth demonstrate that C. compressus and C. bequaerti are closely related.

A comparative analysis of the postcranial skeletal morphology of three species of pakicetid cetaceans provides new insights into their locomotor behavior. In gross morphology, they are similar to their smaller early artiodactyl relatives, lacking obvious signs of their transition to an aquatic niche. Features linking them are related to a cursorial adaptation centered in the reduction of joint mobility to the parasagittal plane, evident in both the elbow and the ankle. In addition to cursorial features of the limbs, the earliest whales and early artiodactyls both possess a long, stable lumbus and robust tails. The three pakicetid genera can be distinguished by size, proportion, and details of articular morphology. However, all pakicetid postcrania bear microstructural specializations commensurate with aquatic locomotion, and incompatible with cursoriality. The most striking modification is the presence of systemic increased bone density, likely used as skeletal ballast. When both postcranial morphology and microstructure are considered, it can be concluded that pakicetid cetaceans were highly adapted for an aquatic niche. As in several extant semiaquatic taxa, the pakicetid tail undoubtedly contributed to its locomotor repertoire, whether in propulsion or stabilization.

Two new insect-related ichnogenera are reported in fossil dinosaur bones from Upper Cretaceous continental strata in Madagascar and Utah. Cubiculum ornatus n. igen. and isp. is described from numerous fossil bones in the Upper Cretaceous Maevarano Formation of northwestern Madagascar, and consists of hollow, ovoid chambers with concave flanks excavated into both spongy and compact bone. Traces similar in morphology to Cubiculum ornatus have been reported elsewhere in North America, Asia, Europe, and Africa in bones ranging in age from Jurassic to Pleistocene, and have been interpreted as pupal chambers constructed by carrion beetle larvae. Osteocallis mandibulus n. igen. and isp. is described in dinosaur bones from continental deposits of the Upper Cretaceous Maevarano Formation of Madagascar and the Upper Cretaceous Kaiparowits Formation of southern Utah. O. mandibulus consists of shallow, meandering surface trails, composed of numerous arcuate grooves, bored into compact (cortical) bone surfaces, and is tentatively interpreted as a feeding trace. Based on similar patterns of bioglyph preserved in both Cubiculum ornatus and Osteocallis mandibulus, the tracemaker is interpreted to be the same or similar for both borings. Given the recurrent association with animal remains, the tracemaker is furthermore presumed to be a necrophagous or osteophagous insect that used bone as a substrate for both reproduction (C. ornatus) and feeding (O. mandibulus).