Sphenothallus and fossils similar to Sphenothallus are found in Ordovician, Devonian, and Mississippian rock units in Ohio and adjacent states and provinces. Although the Ordovician of Québec, Ontario, and Indiana has yielded parts of tubes, Ordovician specimens from southwest Ohio and nearby areas consist almost entirely of holdfasts on hardgrounds and shelly fossils. Sphenothallus is abundant in the Chagrin Shale (Famennian) of northeast Ohio where it is found in about four percent of concretions that contain identifiable fossils. The Chagrin specimens, usually parts of tubes, are occasionally preserved three-dimensionally. The rate of distal expansion of Chagrin Sphenothallus tubes varies intraspecifically; thus, this rate cannot be used to distinguish species. Some Chagrin specimens are attached to larger, conspecific specimens and to articulate brachiopods. Brachiopods have also been found attached to Chagrin Sphenothallus. Bedford-Berea sequence (Famennian) specimens from northern Kentucky and Meadville Member (Kinderhookian or Osagian) specimens from the Cuyahoga Formation of northeast Ohio are usually preserved as flattened tubes. In both occurrences tubes are similar in width, indicating that individuals in each assemblage are probably the same age. Meadville tubes possess characteristics diagnostic of Sphenothallus, but Bedford-Berea specimens, which lack longitudinal thickenings and exhibit little tube tapering, cannot be assigned to Sphenothallus sensu strictu.

Sphenothallus was a gregarious, opportunistic species, tolerant of dysaerobic conditions and able to colonize environments ranging from hardgrounds to soft, muddy sea bottoms. No distinct branching was observed among the Chagrin, Bedford-Berea, or Meadville specimens, suggesting that larval dispersal was the primary mode of reproduction for the genus.

A new genus and species of tentaculitid, Hidagaienites arcuatus, is described from calcareous beds near the Carboniferous–Permian boundary in the Hida-Gaien Terrane, Central Japan. Its mode of occurrence excludes the possibility that the specimens are derived from older strata. Thus, this tentaculitid represents the youngest record of the class Tentaculitoidea, which was previously thought to have become extinct in the Late Devonian.

Abundant and morphologically fairly diverse siliceous sponge spicules of Darriwilian (Middle Ordovician) age were collected from the Table Cove Formation of Port au Port Peninsula, western Newfoundland. Without co-occurrence of appropriate sponge body fossils, it is difficult to refer these disarticulated sponge spicules to existing or to new taxa. However, representatives of demosponges and hexactinellids are recognized. While marked differences are noted between older and younger lithistid dendroclones, for example, spicule form in these Middle Ordovician specimens is similar overall to previously known assemblages of various ages, demonstrating the morphologically conservative nature of the spicular skeleton.

Stromatoporoids from the Brassfield Formation (Early Silurian, Llandovery) near Fairborn, Ohio, provided substrata for a diverse epizoic community. The stromatoporoids were colonized by at least 28 taxa, including bryozoans, cnidarians, echinoderms, annelids, and endolithic organisms. Analysis of the occurrence, diversity, distribution, and coverage of the epizoans recognized patterns of site-selective attachment on the surface of the stromatoporoids.

The upper surface of the stromatoporoids had a slightly higher total epizoan coverage than the lower surface. Concentric zones outlined from the margin also had differences in area and percent coverage. On the upper and lower surfaces, epizoan occurrence decreased from the margin to the interior. Epizoan coverage for the lower surface also decreased inward. On the upper surface, the middle zone had the highest coverage followed by the outer and polar zones, respectively. Among the major invertebrate phyla, only the echinoderms were randomly distributed. Bryozoans, cnidarians, and miscellaneous taxa including borers, cornulitids, and spirorbids were distributed nonrandomly on the surface of the stromatoporoids.

Over 95 percent of the stromatoporoid area analyzed is not covered by epizoans. However, epizoans are commonly clumped or in direct contact with one another. These physical interactions are the result of site-selective attachment by epizoans in close proximity rather than competition for available space.

Saffordophyllum newcombae Flower, 1961, displays unique abilities and an unprecedented range in types of corallite increase. Cerioid growth was characteristic, but colonies on soft substrates could grow in a tollinaform manner during early astogeny. The capacity for recovery from damage and partial mortality is amazing. Rejuvenation may have been accompanied by peripheral expansion in some cases. Rapid regeneration could involve axial increase. Circular lacunae that formed during recovery became sites of rapid lateral increase or corallite decrease.

Two types of axial increase occurred within coralla. Lateral increase was concentrated mainly along the basal wall and adjacent to certain circular lacunae. In typical cerioid parts of the corallum, lateral increase seldom yielded “adult” corallites, but incipient lateral offsets could be numerous. The level of colony integration was probably moderately high. There was likely soft-tissue continuity among polyps, coordination of polyp behavior, subjugation of individuals for the good of the colony, and perhaps astogenetic control.

Saffordophyllum newcombae is considered to be a tabulate coral, although one type of axial increase is similar to that in a few rugose corals and the other type of axial increase as well as possible peripheral expansion resemble modes of increase in some coralline sponges. Lateral increase is considered compatible with cnidarian rather than poriferan biology. Corallite size is typical of tabulates. Saffordophyllum may not be the direct ancestor of favositid tabulates, and may not even be closely related to them; S. newcombae is very different from Paleofavosites and Favosites.

The remarkable range in forms of increase discovered in S. newcombae demonstrates the critical need for detailed paleobiologic studies, if we are to understand the early evolutionary history of corals and to establish reliable criteria for distinguishing various coral groups and homeomorphs.

The poorly known type species of Lingulella, Lingula davisii M‘Coy, 1851b, is redefined from new material collected from the type locality and horizon (Upper Cambrian, North Wales). Lingulella is similar to Obolus and to Ungula in its musculature, mantle canals, and pseudointerareas, but has a thinner shell and irregular pits over its internal surface, concentrated in the visceral areas. A dissolution method that can facilitate the study of lingulate brachiopods preserved in clastic lithologies is described, and its wider adoption is recommended in order to reveal diagnostic morphological characters.

Development of the ventral muscle field has been studied in 12 genera of clitambonitidine brachiopods: Eremotoechia, Clitambonites, Vellamo, Pahlenella, Lacunarites, Oslogonites, Gonambonites, Estlandia, Anchigonites, Kullervo, Antigonambonites, and Raunites. The last two have a pseudospondylium instead of spondylium, which links them to polytoechiids. The spondylium of the studied genera is not derived from convergent dental plates, but develops from the free plate in the early phase of morphogenesis. The early growth stages of spondylium triplex and simplex are identical. The hypothetical ancestor of clitambonitidines with spondylium was presumably a protorthid-like brachiopod probably of the mid-Cambrian age. On the contrary, polytoechiids, as well as Antigonambonites and Raunites, may have been derived from a late Cambrian billingsellid with dental plates. The polyphyly of clitambonitidines follows from development of their ventral muscle field.

The cyrtospiriferid brachiopod genus Tenticospirifer Tien, 1938, is revised based on restudy of the type species from the Frasnian (Late Devonian) of the Russian Platform. As revised the genus includes cyrtospiriferid species with pyramidal ventral valves, catacline ventral interareas, a narrow delthyrium, few sinal plications, and lack a median dorsal septum and pseudodeltidium. All species retained in the genus are of Givetian and Frasnian age. All Famennian age species described from South China and North America are rejected from the genus. It appears that Tenticospirifer evolved during the early Givetian in western Europe and remained endemic to that region during the remainder of the Givetian. Successive migrations of Tenticospirifer from eastern Laurussia to North America, then to South China and possibly Australia, coincided with middle and late Frasnian eustatic sea level rises, respectively. The North American species Spirifera cyrtinaformis Hall and Whitfield, 1872, and related species identified as Tenticospirifer by North American workers, are reassigned to Conispirifer Lyashenko, 1985. Its immigration to and widespread dispersal in carbonate platforms of western Laurussia, northern Gondwana and tropical island arcs (?) coincided with a major late Frasnian eustatic sea level rise. The new family Conispiriferidae is proposed with Conispirifer Lyashenko, 1985, selected as the type genus. The new family also includes the new genus Pyramidaspirifer with Platyrachella alta Fenton and Fenton, 1924, proposed as the type species. The affinity of the new family remains uncertain pending restudy of key genera currently included in the Superfamily Cyrtospiriferoidea. Available data from the Devonian brachiopod literature indicate that species of Pyramidaspirifer are restricted to late Frasnian deposits of central and western North America.

The lower part of the Shinarish Formation of Djebel Sinjar, northwest Iraq, yields an ammonite assemblage of Upper Campanian age dominated by heteromorph taxa: Nostoceras (Nostoceras) ellipticum new species, N. (N.)(?) budanyi Foldyna and Vašiček, 1977, N. (N.) cf. hyatti Stephenson, 1941, Exiteloceras(?) etequense Lewy, 1969, Didymoceras sp., unassigned nostoceratid fragments, Solenoceras reesidei Stephenson, 1941, and Lewyites oronensis (Lewy, 1969), together with the normally coiled Hauericeras (Gardeniceras) sp. Several of the species present also occur in the lower part of the Mishash Formation in Israel, in the Gulf Coast region of the United States, and as rarities in the U.S. Western Interior. All occurrences are compatible with an Upper Campanian attribution.

Decapod crustaceans bearing major claws with long, slender fingers armed with pectinate (comblike) denticles have been described in six genera arrayed within three families (Polychelidae, Nephropidae, and Ctenochelidae) in three infraorders (Palinura, Astacidea, and Anomura, respectively). Only one or a few genera in each infraorder exhibit this claw form. The pectinate claw form is confidently interpreted as having evolved independently in four lineages: once in the Polychelidae, once in the Ctenochelidae, and twice in the Nephropidae. Three of the lineages are known from both the fossil record and modern seas; the polychelid form is known only from Jurassic rocks. Convergence in this claw form developed to the extent that isolated fossil claws (i.e., claws without associated bodies) have commonly been misidentified at high taxonomic levels. The fossil record confirms what seems intuitively reasonable: that claw morphology is prone to convergence and should not, by itself, be given a high degree of taxonomic importance.

A new species of Late Ordovician callocystitid rhombiferan (Glyptocystitidae), Lepadocystis decorus, is described from the Brainard Shale of north-central Illinois. This species is characterized by five pectinirhombs, open infralateral and lateral plate circlets, and well-developed ridges on the thecal plates. Lepadocystis decorus well illustrates that open vs. closed plate circlets in glyptocystitids can largely be a function of pectinirhomb length and is therefore in part an ontogenetically linked characteristic. Consequently, great care must be taken to assure maturity when using this feature in taxonomy.

A microevolutionary event involving the conodont Paroistodus lineage is documented in the Gualcamayo Formation (Middle Ordovician), Argentine Precordillera. A detailed sampling of limestones throughout the upper part of the San Juan Formation and the lower member of the Gualcamayo Formation yielded over 14,000 well-preserved conodont elements. Paroistodus originalis (Sergeeva, 1963) was recorded through the upper 230 m of the San Juan Formation and the lower member (10 m thick) of the Gualcamayo Formation. The derived species Paroistodus horridus (Barnes and Poplawski, 1973) was recorded throughout the middle member of the Gualcamayo Formation (65 m thick). The intermediate linking forms between both species are identified as two new taxa: Paroistodus horridus primus Albanesi, 1998b, and P. h. secundus Albanesi, 1998b. They were recorded in the uppermost 70 cm of the lower member. Apparently, the speciation event occurred under stressed environmental conditions with the drowning of the carbonate platform, i.e., the San Juan Formation, and the beginning of a deeper and restricted environment represented by the Gualcamayo black shales. The demise of the carbonate production was caused by a sea level rise and a significant influx of volcanic ashes. The punctuated speciation event occurred within an allopatric setting while the Precordillera occupied an isolated (Iapetus) oceanic position in its overall drift from Laurentia to Gondwana.

Two ichthyosaurian specimens from the Upper Jurassic lithographic limestones of Bavaria, namely an almost complete skeleton with soft tissue impression and another partial one, are described for the first time. Both belong to the same taxon, which is mainly characterized by a long and slender snout; numerous small, delicate, packed, and well-anchored teeth; a medium size orbit; a reduced triangular squamosal in the cheek region; an angular largely exposed laterally reaching as far anteriorly as the surangular; a humerus with three distal facets for radius, intermedium and ulna; an extrazeugopodial element anterior to the radius; a very reduced hindlimb; packed polygonal paddle elements; and a bipartite pelvis with a distally greatly expanded puboischiatic complex. This combination of characters permits differentiation from all other known genera; moreover, it could be compared to the species inquirendae Ichthyosaurus leptospondylus Wagner, 1853a. A new genus, Aegirosaurus, is created and proposed as a new combination for this species. Aegirosaurus clearly belongs to the clade Ophthalmosauria because of an angular largely exposed laterally and reaching as far anteriorly as the surangular, and the occurrence of an extrazeugopodial element anterior to the radius and the associated digit distal to it. A systematic review of ichthyosaurs from the lithographic limestone of Bavaria (most of them destroyed during World War II) reveals the occurrence of probably three different taxa, namely Aegirosaurus, an indeterminate form close to Ophthalmosaurus or Caypullisaurus, and an indeterminate one possibly close to Nannopterygius.

The skull of the Miocene Yarala burchfieldi Muirhead and Filan, 1995, is described. Analysis of skull morphology supports phylogenetic conclusions based on dental morphology. Y. burchfieldi shares a number of synapomorphies with other peramelemorphians, some of which are unique and help to define this order of marsupials. Y. burchfieldi is the most plesiomorphic peramelemorphian known. Although sharing some derived characters with a number of extant taxa, Y. burchfieldi lacks synapomorphies that unite all other peramelemorphian taxa as the Superfamily Perameloidea. The Yaraloidea and Yaralidae, a new superfamily and family of peramelemorphians, is proposed and diagnosed on the basis of Y. burchfieldi. Fossil evidence supports the late divergence of perameloids, while peramelemorphian diversity in the Tertiary indicates an ancient derivation for the order.

A conifer from the uppermost Permian with small, helically arranged leaves is described from the Guangxi Autonomous Region and Guizhou Province of South China as Szecladia multinervia, new genus and species. The material includes both impression specimens and the first anatomically preserved Paleozoic conifer fossils from China. Shoots are irregularly branched, with small, helically arranged, multiveined leaves. Stems display an endarch eustele with abundant, dense wood. Leaf traces diverge from the stele as a single bundle that divides several times in the cortex and at the base of the leaves, forming about seven or eight parallel veins in each leaf. Szecladia is the earliest known conifer with multiveined leaves and it represents a distinctive coniferous element of the uppermost Permian Cathaysian flora in South China. Szecladia further demonstrates that conifers with wood and leaf venation suggestive of the Podocarpaceae may have evolved by the end of the Paleozoic.

Newly discovered benthic fossils and specimens illustrated in the paleontological literature indicate that drilling predators (or parasites) were present in the Permian. New field data from southern Brazil document the first drill holes ever reported for Permian bivalve mollusks. In addition, a literature review revealed drill holes in shells of articulate brachiopods from Russia, Greece, and West Texas. Holes range in size from 0.1 to 5.8 mm and are typically round, cylindrical, singular penetrations perpendicular to the valve surface. Incomplete, healed, and multiple holes are absent. Drilling frequency, a proxy for predation intensity, is very low: less than 1 percent (this estimate may be seriously affected by taphonomic and monographic biases). Literature data suggest that frequency of drilled specimens varied significantly among higher brachiopod taxa. The geography and stratigraphy of drilled specimens indicate that drilling organisms were worldwide in their occurrence and continuously present in marine ecosystems throughout the Permian. This report is consistent with other recent studies indicating that although drillers were continuously present throughout the Phanerozoic, drilling intensity was lower in the Late Paleozoic and early Mesozoic.