A literature-based compilation of phylogenetic relationships and biometric measurements of 342 Cenozoic planktonic foraminiferal species suggests that the group shows a net increase in size through the Cenozoic, thus appearing to follow Cope's Rule of phyletic size increase. However, when the data are corrected for size-related biases, they do not support the hypothesis that this apparent trend is driven by an organismal adaptive advantage of larger size.

When the planktonic foraminifera return to their “primitive” globigerine morphology during the Eocene-Oligocene transition, there is no indication of size-dependent origination or extinction; however, when the extinction signal is decomposed into pseudoextinctions and true lineage terminations, a differential pulse of pseudoextinction is observed among the smaller forms. This observation suggests that smaller bodied species, rather than surviving stressful times with static morphologies, may evolve their way through times of crisis and go on to found lineages which, by virtue of their initial small size, are stochastically likely to increase in mean size during subsequent diversification. Thus, one general explanation for Cope's Rule might be that smaller bodied species are more adaptively responsive due to their tendency to have shorter generation times. During times of stress, this adaptive responsiveness may give them an advantage that is correlated with, but causally unrelated to, their size.

A fauna of eight taxa of demosponges and hexactinellid sponges has been collected from the Lower Devonian (Lochkovian) Ross Formation, largely out of the upper Birdsong Shale Member in Benton, Decatur, and Perry Counties in west-central Tennessee. The Upper Birdsong Shale (“bryozoan zone”) in which the sponges are most common appears to have been deposited below normal wave base in a quiet marine environment, and represents a terrigenous clastic sediment influx onto a carbonate shelf that had existed in the area from at least the middle Silurian. Benton Quarry in Benton County was the most productive locality for fossil sponges.

The new demosponge genera and species Ginkgospongia foliata and Coniculospongia radiata occur with the new species Haplistion lobatum and skeletal mats of fine spicules, along with moderately rare specimens of Hindia sphaeroidalis Duncan. The new hexactinellid genus and species Stiodermiella amanita and Stiodermiella tetragona are characterized by peculiar ornamented papillose, swollen spicules that produce a massive, armored layer on the upper part of the sponge. The latter are associated with the new hexactinellid species Twenhofelella bulbulus, which has relatively normal-appearing hexactines, and with an indeterminate hexactinellid genus, which has spinose hexactines in irregular orientation in a small, platelike fragment. Root tufts of probable hexactine origin also occur.

Swollen spicules in Stiodermiella are reminiscent of swollen spicules in the family Stiodermatidae Finks, largely from the Permian of western Texas, but elements of the family are also known from Lower Carboniferous to Permian rocks in Europe and North America.

Well-preserved silicified sponges have been recovered from the Upper Permian Changxing Formation at Huangnitang in western Hubei province. The new species Cystauletes grossa and Cystothalamia irregulara are associated with Cystothalamia sp., Colospongia salinaria irregularis Zhang, 1983, Sollasia ostiolata Steinmann, 1882, Virgola? osiensis (de Gregorio, 1930), a questionable inozoan species, and a form questionably referred to the genus Hikorodium? sp. These sponges were detrital fragments that accumulated at the toe of the forereef, at the margin of slope fades and basin fades, at Huangnitang. Amblysiphonella vesiculosa minima Zhang, 1983, is represented in the collections from the Upper Permian Heshan Formation at the village of Guwu, near Heshan City in central Guangxi. Heshan beds that produced the silicified sponges are of Wujiapingian age and accumulated on a normal-marine, shallow-water carbonate platform, or in skeletal shoals within the carbonate platform, and represent a level-bottom community.

Givetian species of Chinese brachiopods previously assigned to the genus Spinatrypa or Spinatrypina reveal an internal structure characteristic of other species referred to the Eifelian genus Kerpina and the cosmopolitan Frasnian genus lowatrypa. Serial sections clarify the nature of the Middle Devonian Chinese species, which are described here as a new genus, Invertina (type species, Atrypa aspera var. sinensis Kayser, 1883). The internal structure of the Late Devonian type species of Iowatrypa, Atrypa owenensis Webster, 1921, is illustrated for the first time for comparison. These three genera, as well as three other genera, are referred to a new Devonian (Emsian-Frasnian) subfamily, the Invertininae, allocated to the family Atrypidae.

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.

Newly discovered trigonioid bivalves are systematically described from the Late Albian of the Fossil Bluff Group of Alexander Island, Antarctic Peninsula. The fauna includes Nototrigonia (Nototrigonia) ponticula Skwarko, N. (Callitrigonia) offsetensis n. sp., Eselaevitrigonia macdonaldi n. sp., Pterotrigonia (Pisotrigonia) capricornia (Skwarko), and Pacitrigonia praenuntians n. sp. It represents the first Albian trigonioid fauna described from the Antarctic. It is also the first published record of the Nototrigoniinae (excluding Pacitrigonia) outside Australasia. Paleoecologically, this fauna represents the shallowest and highest energy molluscan assemblage from the Fossil Bluff Group and occurs near the base of a significant transgressive unit, the Mars Glacier Member of the Neptune Glacier Formation. The paleogeography of Austral Cretaceous trigonioids is reviewed. Endemic centers are identified in India–east Africa, southern South America, and Australasia. Only one trigonioid genus, Pacitrigonia, had its origin in the Antarctic. During the earliest Cretaceous, cosmopolitan trigonioid genera occurred in Antarctica. In the mid-Cretaceous faunal similarity of Antarctica with Australasia was strong, and in the latest Cretaceous affinity with southern South America increased.

Demonstrating stasis in the fossil record has proven to be problematic with respect to both data collection and analysis. A previous approach is morphometric analysis of lineages sampled temporally and geographically. A hypothesis of stasis is apparently supported if morphological distances between descendent species and ancestral species are no greater than those between geographically distant samples of the descendent species. Evidence presented in this paper conflicts with such interpretations for at least one bivalve lineage, Chione erosa–Chione cancellata, of the late Neogene of tropical America. The direction and magnitude of morphological variance were quantified between two geographically distant groups of C. cancellata from the Recent, and compared to Pleistocene samples of C. cancellata and Pliocene samples of C. erosa. The results indicate that, although the magnitude of intraspecific geographic variation is as great as interspecific temporal variation, the species are morphologically discrete groups. The direction of morphological variance is as important as its magnitude, and interpretations overlooking this point are at best equivocal.

The stratigraphic section at Aidaralash Creek, northern Kazakhstan, provides a complete and well-developed succession of strata across the Carboniferous–Permian boundary. This section, containing abundant and well-preserved ammonoid, fusulinacean, and conodont faunas, can serve well as the Carboniferous–Permian boundary stratotype. A profound change in ammonoid faunas, which occurs at the Orenburgian–Asselian boundary and which has been recognized by previous workers (e.g., Ruzhencev, 1950, 1951, 1952; Bogoslovskaya and Popov, 1986a, 1986b; Furnish, 1973; Glenister and Furnish, 1981), occurs in the Aidaralash Creek section, at the boundary between beds 19 and 20, and serves to mark the Carboniferous–Permian boundary. Additionally, Lower Permian strata at Aidaralash Creek mark the first appearance of widespread Permian ammonoid taxa, including representatives of Svetlanoceras, Juresanites, Prostacheoceras, Tabantalites, and Kargalites, that are preceded by the extinction of characteristic Late Carboniferous genera such as Prouddenites, Uddenites, Shumardites, Vidrioceras, Schistoceras, and Subkargalites.

Agnostus acadicus Hartt (in Dawson, 1868) was the first agnostoid trilobite to be described from Middle Cambrian strata in North America. It was later designated the type species of Acadagnostus Kobayashi, 1939. The original description of A. acadicus was based on two specimens, a cephalon and a pygidium, which are illustrated for the first time with photographs. These are interpreted to represent separate species, each belonging to a different genus. The holotype cephalon is reassigned as Peronopsis acadica, which is judged to be a subjective senior synonym of Agnostus fallax Linnarsson, 1869, and several other species-group taxa. Consequently, Acadagnostus is suppressed as a subjective junior synonym of Peronopsis. Agnostus fallax is the type species of Axagnostus Laurie, 1990, which also is suppressed as a subjective junior synonym of Peronopsis. The pygidium on which the original description of A. acadicus was based is reassigned to Hypagnostus parvifrons (Linnarsson, 1869).

Peronopsis acadica, as emended, is a common, cosmopolitan agnostoid in open-marine lithofacies. It has an observed stratigraphic range from the Ptychagnostus praecurrens Interval-zone to the Ptychagnostus punctuosus Interval-zone.

Maurotarion Alberti, 1969, is a diverse otarionine clade that can be readily distinguished from Harpidella M'Coy, 1849. Both genera appear in the Upper Ordovician and range until the Middle Devonian. A new diagnosis for each taxon is given. New species of the genera from the Ordovician and Silurian of the central Mackenzie Mountains, Northwest Territories, Canada, include Harpidella kurrii (Ashgill), H. tikkaneni (Llandovery), H. greggi (Wenlock), and Maurotarion messieri (Llandovery). Harpidella megalops (M'Coy, 1846), H. triloba (Hu, 1975), H. spinafrons (Williams in Cooper and Williams, 1935), Maurotarion struszi (Chatterton, 1971), and M. instita (Whittington and Campbell, 1967) are revised.

Aulacopleurine trilobites from Llandovery strata of the Whittaker Formation in the central Mackenzie Mountains, Northwest Territories, Canada, include Aulacopleura andersoni n. sp., Aulacopleura? ranfordi n. sp., and Songkania smithi n. sp. The subfamily Aulacopleurinae consists of only the genera Aulacopleura Hawle and Corda, 1847, and Songkania Chang, 1974, characterized by smooth, broad early growth stages and holaspides having expanded frontal and genal areas, covered with dense caecal pits, but usually very subdued tuberculate sculpture. The relationship of Aulacopleura? ranfordi and A.? reedi Přibyl, 1947, to the remainder of species assigned to the genus is ambiguous.

Twenty-four nearly complete carapace samples were collected at three different localities of the Maastrichtian (Late Cretaceous) Cárdenas Formation in San Luis Potosí, east-central Mexico. The material has been assigned to five families: the Callianassidae, Dakoticancridae, Carcineretidae, ?Majidae, and Retroplumidae. Two genera of callianassid shrimp are described, Cheramus for the first time in the fossil record. Dakoticancer australis Rathbun is reported as the most abundant crustacean element; one new genus and species of carcineretid crab, Branchiocarcinus cornatus, is erected, and a single, fragmentary specimen is questionably referred to the Majidae. The three localities reflect paleoenvironmental differences, exhibited by different lithologies, within marginal marine, lagoon environments. The record of dakoticancrid crabs in the Cardenas Formation extends the paleobiogeographic range of the family and the genus Dakoticancer. Carcineretid crabs, although not abundant, seem to have been a persistent element of crustacean assemblages in clastic environments during the Late Cretaceous of the ancestral Gulf Coast of Mexico.

Two species of eoparisocrinid crinoids from the Middle Ordovician Galena Group of northern Iowa and southern Minnesota are described, namely Eoparisocrinus crossmani n. sp. and E. grandei n. sp. The post-larval development of Eoparisocrinus crossmani is examined. Crinoid arms grow by addition of new plates at their distal tips in conjunction with calcite deposition on old plates. New branches appear where axillary plates are initiated. Consequently, the growth rates for number of brachials and length of food-gathering system compared to crown volume are much faster than if the animals were isometric. The number of food particles collected is related to the number of food-catching tube-feet, which can be estimated if the length of the arms and height of the covering plates are known. The size of the largest food item is constrained by the food groove width. Thus, food-gathering capacity is the number of food-catching tube-feet multiplied by food groove width. The food-gathering capacity increases more rapidly than if the animal grew isometrically, and the ratio of food-gathering capacity: crown volume only declines slightly over the known growth range. All Ordovician cladid crinoids examined follow nearly identical ontogenetic trajectories. The ecological niche of a stalked crinoid is related to four basic parameters: stem length, food groove width, tube-foot spacing, and branch density. Stem length limits the highest elevation above the seafloor. The column of E. crossmani becomes longer during ontogeny due to the formation of new columnals and height growth of old ones. Consequently, individuals gradually “move up” until the adult elevation of about 50 mm is reached. The growth rates of stem length relative to crown size are slow in the youngest and mature animals but rapid in juveniles. The food grooves become wider throughout growth so that older crinoids ate larger food particles than younger ones. The food groove width increases less rapidly than if the shape were constant, because distal plates and branches are more narrow and have more slender food grooves than proximal plates. Growth curves for food groove width versus stem length and elevation were generated for E. crossmani and other crinoids that commonly occur in the same beds. Together, elevation and food particle size define the main dimensions of the niche. The various taxa are more or less separated by different food groove widths at most comparable elevations. This pattern minimizes ecological overlap and probably competition between the different species. The tube-foot spacing of E. crossmani is constant regardless of size, which suggests that it employed the same type of feeding mechanism throughout post-larval ontogeny. The arm branches of adults gradually become less densely spaced relative to the area of water filtered than in juveniles.

Camptocrinus alabamensis Strimple and Moore, from the Gasperian (Mississippian: Chesterian) part of the Monteagle Limestone and overlying Bangor Limestone in northern Alabama, is the only species of Camptocrinus known to have more than 10 arms. Camptocrinus alabamensis exhibits morphological features (basals that are taller on their posterior ends than on their anterior ends, flattened primanal, shorter posteriormost secundibrachs on C ray and D ray) indicative of a tightly coiled life position, with most of the stem lying along the sediment. Unlike other coiled crinoids, Camptocrinus alabamensis had a double-folded stem and more than 10 arms, which we interpret to have been compromise solutions to the problems of protection from high current energy and predation pressure coupled with the need to lift the animal into a feeding posture. In addition, C. alabamensis is the only dichocrinid exhibiting highly modified pinnules, which may have been used as rheo/chemosensory organs. Camptocrinus alabamensis was a leeward passive suspension feeder that, in times of danger, could fold in its arms and coil tightly against the sediment.

Camptocrinus alabamensis is removed from synonymy with C. cirrifer and the diagnosis of Camptocrinus is modified. Species of the genera Camptocrinus and Neocamptocrinus should be used only for specimens in which calyces are known; therefore, the plethora of stem-species erected over the years should all be assigned to stem genera unless adequate calyx descriptions are available.

Aldebarania arenitea (Astropectinidae; Asteroidea; Echinodermata) is described from the Rocky Point Member of the Maastrichtian (Upper Cretaceous) Peedee Formation of North Carolina. A turbulent, shallow-water environment is suggested by sedimentary features, a diverse marine fauna, and the morphology of Aldebarania. Aldebarania appears to be a partial ecological equivalent of living Astropecten and Luidia; however, phylogenetic relationships within the Astropectinidae are unstudied and the origin of similarities is unknown.

Species of Ivanovia (Codiaceae or Udoteaceae, Chlorophyta) have traditionally been characterized as phylloid or leaf-like. Extraordinarily well preserved specimens of I. tebagaensis in limestone from the Upper Permian of southern Tunisia indicate that the thallus was cyathiform or cup-shaped, similar to the broadly conical codiacean Calcipatera and to living Udotea cyathiformis. Ivanovia also shared with Calcipatera the same general membrane structure consisting of bilateral cortices with palisades of utricles, now filled with micrite, and a medulla of tubular coenocytes, now filled with sparry calcite mosaic. A cyathiform thallus would have had an inner and an outer cortex and those of I. tebagaensis were dimorphic. The utricular structure as usually seen in thin sections using transmitted light is much clearer when viewed on polished surfaces of hand specimens using reflected light. Commonly occurring fused membranes suggest that the thalli reproduced vegetatively by budding. The complexity and regularity of the I. tebagaensis membrane structure strongly suggest that a model which proposes that Ivanovia is simply a diagenetic stage in the fossilization of the red alga, Archeolithophyllum, is invalid.

Two new specimens of Periastron reticulatum Unger emend. Beck have been collected from the Erin Slate, Talladega Slate Belt, southern Appalachians. Preserved anatomical features provide a basis for an expanded understanding of the genus and provide a biostratigraphic basis for dating the uppermost unit of the Talladega Slate Belt.

A branched, scratch-ornamented burrow system is described from early Pleistocene sediments of Sicily, Italy. The trace fossil occurs in a bed of volcanic ash beneath a shallow marine silty unit and is remarkable in possessing enlarged, ovoid chambers above the multiple branching points of a maze. The structure, named Spongeliomorpha sicula, was probably produced by crustaceans. A likely interpretion is as an agrichnion, in which microbial gardening took place in the chambers.