Two new Deseadan interatheriine genera (Interatheriidae, Notoungulata) from the late Oligocene Salla Beds of Bolivia are described. Both are monotypic and one is known from a partial skeleton, a rarity among known pre-Santacrucian interathere taxa. Phylogenetically, both taxa nest well within Interatheriinae, showing characteristically bilobed p3–4. Both taxa also have derived characters (hypselodont cheeckteeth, persistent lingual sulcus on upper molars) relative to basal interatheriines such as Santiagorothia and Proargyrohyrax but are clearly plesiomorphic with respect to younger, more highly derived Santacrucian interatheriine taxa such as Interatherium and Protypotherium. New species Brucemacfaddenia boliviensis is on average larger than the other new Salla interatheriine, Federicoanaya sallaensis, although they do overlap in size. Distinguishing between the two new taxa based purely on molar morphology is confounded by lack of diagnostic characters on the molar teeth and the overlap in size between the taxa. We overcome this difficulty of identifying specimens that preserve only molars by using discriminant analysis. We present a few of the simpler yet still robust discriminant functions we used so that future workers have a means of identifying problematic specimens. Analysis of Salla interathere specimens and stratigraphic provenance indicates both taxa experienced a modest increase in body size upsection, the driving mechanism for which remains unknown, but could be environmental changes or simple drift. These two new taxa help emphasize the fact that while the Salla fauna shares elements with roughly contemporaneous Deseadan faunas from more southerly latitudes, important faunal distinctions mark the two regions as well.

Acid processing allowed systematic identification of 458 Upper Triassic silicified scleractinian corals (20 genera, 47 species) from the Alexander terrane (southeast Alaska) and Wrangellia (Wrangell Mountains, southern Alaska and Vancouver Island, Canada). Coral faunas, here presented, show taxonomic affinity with coeval collections from other Cordilleran terranes, specifically the Wallowa terrane (northeastern Oregon and Idaho) and Peru (South America) as well as the distant Tethys region. Genera from the Alexander terrane include: Kompsasteria Roniewicz, Gablonzeria Cuif, Cuifia Melnikova, Paracuifia Melnikova, Distichophyllia Cuif, Retiophyllia Cuif, Kuhnastraea Cuif, Margarosmilia Volz, Distichomeandra Cuif, Astraeomorpha Reuss, Pamiroseris Melnikova, Crassistella Roniewicz, Stylophyllum Frech, and Meandrostylis Frech. Genera from Wrangellia include: Gablonzeria Cuif, Distichophyllia Cuif, Retiophyllia Cuif, Kuhnastraea Cuif, Margarosmilia Volz, Distichomeandra Cuif, Astraeomorpha Reuss, Parastraeomorpha Roniewicz, Chondrocoenia Roniewicz, Pamiroseris Melnikova, Crassistella Roniewicz, Ampakabastraea? Alloiteau, Recticostastraea Stanley and Whalen, Meandrostylis Frech, Anthostylis Roniewicz, and the new genus Campesteria n. gen. New species include: Gablonzeria grandiosa n. sp., Paracuifia smithi n. sp., Paracuifia jennieae n. sp., P. anomala n. sp., Retiophyllia dendriformis n. sp., R. obtusa n. sp., and Campesteria prolixia n. sp.

A variety of Pennsylvanian sponges have been recovered from exposures along the shore of Lake Bridgeport and in nearby areas in Wise County, north-central Texas. Calcareous and hexactinellid sponges have locally weathered out of the Jasper Creek Shale (=upper Lake Bridgeport Shale) and the overlying Devil's Den Limestone of the Graford Formation, of Late Pennsylvanian Missourian age.

The Demospongea protomonaxonids Heliospongia excavata King, 1933, and Coelocladia spinosa Girty, 1908 are represented in the studied collections by several specimens, as is the new genus and species Luterospongia texana. Agelasid ceractinomorph demosponges are represented by the fissispongiid Fissispongia jacksboroensis King, 1938, the maeandrostiid Maeandrostia kansasensis Girty, 1908, and the girtycoeliid, Girtycoelia typica King, 1933. Sponges of the Class Hexactinellida and the amphidiscophorid Family Stiodermatidae are represented by an extensive suite of specimens of the new genus and species Dermosphaeroidalis irregularis. Representatives of the hexactinellid reticulosid sponges include some unusually large specimens of the vase-shaped Endoplegma calathus Finks, 1960, of the Family Docodermatidae, and fragmental specimens of ?Stereodictyum orthoplectum Finks, 1960, of the Family Stereodictyidae. One unclassified root tuft fragment is also described and illustrated.

Much of this diverse sponge fauna was endemic to the western embayment of Pangaea.

Late Mississippian and earliest Pennsylvanian trilobite faunas of North America are dominated by the Paladin and Kaskia clades. Phylogenetic analysis of middle Carboniferous species of these clades demonstrates the close ancestral relationship between these groups. The Kaskia clade consists of eight species: K. chesterensis Weller, 1936, K. osagensis (Cisne, 1967), K. longispina (Strong, 1872), K. wilsoni (Walter, 1924), K. genevievensis (Walter, 1924), K. rosei (Cisne, 1967), K. gersnai n. sp., and K. rollinsi n. sp. Kaskia Weller, 1936 ranges from late Osagean to middle Chesterian (early Visean-early Serpukhovian) and is restricted to cyclothemic shelf and nearshore deposits. Species of Kaskia appear to have evolved in areas of shallow water and high environmental stress. The Paladin clade consists of 12 species including previously named species P. morrowensis (Mather, 1915), P. girtyianus Hahn and Hahn, 1970, P. rarus Whittington, 1954, P. helmsensis Whittington, 1954, and P. moorei (Branson, 1937). New species belonging to this clade are Paladin moorefieldensis n. sp., P. pleisiomorphus n. sp., P. imoensis n. sp., P. mangeri n. sp., and P. wapanukaensis n. sp. This group ranges from the early Chesterian to early Morrowan (late Visean-late Bashkirian). Species of Paladin appear to be confined to outer shelf shelf-edge and off-shelf facies where presumably deeper water environments existed. This is manifested in their paleogeographic distribution, which is paleoenvironmentally controlled.

Seemingly consistent proportional differences in several palatal structures have been noted between Permian and Triassic anomodont therapsids for nearly a century. These patterns have been cited as evidence in support of a decline in atmospheric oxygen concentrations that may have contributed to end-Permian terrestrial extinctions. However, it is not known whether the observed differences are significant, or whether they stem from continued directional selection. If they are not significant, or if their timing does not match that proposed for the oxygen decline, support for the hypoxia-based extinction scenario would be weakened. We tested whether the internal nares and bony secondary palate, two palatal features proposed to be related to respiratory efficiency, are significantly larger in Triassic anomodonts, and whether the variation can be attributed to a long-term tendency for increase. Results based on raw data indicate that Triassic anomodonts have significantly larger secondary palates than Permian anomodonts. They also have significantly larger internal nares, but only when primitive, morphologically-divergent specimens are not considered. Although nares and palate size are correlated with stratigraphic occurrence, available data reject the hypothesis that the observed differences were the result of a long-term trend. Most of these findings are consistent with the predictions of the hypoxia scenario. However, removing the effects of body size and phylogeny causes some of the differences to break down, indicating that if selection for increased respiratory efficiency affected these characters, it was most likely not the only factor to do so. Therefore, the characters provide only weak evidence in support of the hypoxia scenario, and we recommend against their use for this purpose. Our results emphasize the need for caution when invoking presumed differences between Permian and Triassic vertebrates as support for hypoxia, or other extinction scenarios, without a rigorous study of the character(s) in question.

Microscopic teeth isolated from the early Cambrian Mahto Formation, Alberta, Canada, are identified as components of a molluscan radula, the oldest on record. Tooth-rows are polystichous and lack a medial rachidian tooth-column. Anterior-posterior differences in tooth-row morphology are interpreted as ontogenetic and correspond broadly to the diversity of isolated teeth, some of which correspond closely with those of extant aplacophoran molluscs. Associated pock-marked cuticular fragments are interpreted as having supported multiple biomineralized sclerites/spines in the manner of a modern chiton girdle. On the assumption that the cuticle and radula derive from the same species, there is a strong case for identifying this fossil as an aculiferan (aplacophoran polyplacophora) mollusc, possibly a stem-group chiton. Similarities between the Mahto radula and the feeding apparatus of Wiwaxia and Odontogriphus are shown to be superficial. Terminal wear on some of the Mahto teeth indicate that they were used to scrape hard-substrates.

The Mysidiellidae are morphologically isolated among Triassic bivalves but share important characters with Late Paleozoic Ambonychioidea. Apart from a great similarity in the general shape of the shell, the most primitive mysidiellid genus Promysidiella resembles ambonychioids in the presence of a duplivincular-opisthodetic ligament system. Within the Mysidiellidae, this ligament type evolved into the transitional ligament system that characterizes Late Triassic Mysidiella. The phyletic polarity indicates that this evolution probably took place by paedomorphosis. New examinations of the shell microstructure of Mysidiella demonstrate the presence of simple prismatic and possibly foliated structures in the calcitic outer shell layer, which further supports an ambonychioid affinity. Therefore, the Mysidiellidae are removed from the Mytiloidea and assigned to the Ambonychioidea. The poorly known genus Protopis, which was originally included in the Mysidiellidae, probably had a parivincular ligament system and was hence a member of the Heteroconchia. Joannina, which was previously considered a junior synonym of Protopis, is re-established. The hinge margin of Joannina carries a well developed nymph but lacks teeth. These characters as well as its modioliform shape, anterior shell lobe, and pronounced diagonal carina link Joannina with the Late Triassic genus Healeya (Modiomorphoidea). Both taxa are herein placed in the new family Healeyidae, which differs from the morphologically similar Kalenteridae in the absence of elaborated hinge teeth. Protopis, as well as the recently described genera Leidapoconcha, Waijiaoella, and Qingyaniola, are tentatively assigned to the Healeyidae.

The penguin skeleton studied here constitutes the fourth partial skeleton found in Patagonia, and the third one with an associated humerus and tarsometatarsus. The finding of this partial skeleton identified with certainty as Palaeospheniscus patagonicus Moreno and Mercerat, 1891 (Aves, Sphenisciformes) allows the first description of elements other than the tarsometatarsus. The material comes from the basal sector of the Gaiman Formation (Early Miocene), located along the Atlantic coast of Chubut Province, south of Rawson city. This unit comprises a succession of shales, fine tuffs, sandstones, tuffaceous sandstones, and coquinas deposited in a shallow marine environment. These beds contain abundant marine vertebrates (sharks, dolphins, rays, birds), mollusk casts, and oyster beds. The skeleton includes: rostrum, two thoracic vertebrae, right coracoid without the distal end, left humerus, right femur, right tarsometatarsus, left fragmentary scapula, left coracoid, left radius without the distal end, proximal portion of left ulna, proximal end of left femur, and preacetabular part of the synsacrum. P. patagonicus would have been a medium-sized penguin weighing about 5 kg that inhabited the breeding colonies established in the nearby Bryn Gwyn area during the early Miocene. Despite the abundance of penguin remains known for Argentina, and the fact that they are among the birds with a better fossil record, this skeleton is an exceptional case. This finding allows a readjustment of the taxonomic criteria applicable to fossil and living species.

Three crinoids are known from the Upper Ordovician Hatter Limestone at Union Furnace in central Pennsylvania, i.e., Haptocrinus buttsi n. sp., an unknown crinoid with a lichenocrinid holdfast, and an indeterminate columnal that probably belongs to a crinoid. Two crowns enable H. buttsi n. sp. to be reconstructed. The animal lived about 70 cm above the seafloor and was attached to a strophomenid brachiopod with a lichenocrinid holdfast. Its endotomous arms formed an efficient filtration net that covered much of the water within its planar filtration fan. The application of filtration theory indicates that H. buttsi n. sp. could begin to feed at a comparatively low ambient current velocity and balance its energy budget. Like many other ramulate disparids, H. buttsi n. sp. mainly collected moderately small food particles. As a member of the Tornatilicrinidae, H. buttsi n. sp. is a relatively primitive disparid. Another crinoid taxon bears a longer and thinner stem and a different type of lichenocrinid holdfast cemented to the same strophomenid shell. A third species, most likely a crinoid, is represented by a single columnal. The fauna lived in a quiet water lagoonal area, which is an unusual habitat for Paleozoic crinoids.

The Cambrian fossil record of the Arachnomorpha is rich and diverse and includes trilobites, chelicerates, and many taxa known from various soft-bodied faunas including the Burgess Shale and the Chengjiang. Exceptionally well-preserved arthropod fossils are also known from Middle Cambrian strata in Utah. Recently, two new arachnomorphs (Dicranocaris Briggs, Lieberman, Hendricks, Halgedahl, and Jarrard, 2008 and Nettapezoura Briggs, Lieberman, Hendricks, Halgedahl, and Jarrard, 2008) were described from the Wheeler and Marjum formations of Utah. Cladistic analysis is undertaken to investigate arachnomorph relationships in light of these two new genera. The character matrix of Edgecombe and Ramsköld (1999) serves as the foundation for this study, augmented by new characters and taxa. The results of our cladistic analysis suggest that at least three distinct arachnomorph clades had diverged by the Middle Cambrian, and perhaps much earlier; the Utah genera can be referred to groups within one of these clades.

This paper presents a description of new gastropods belonging to the superfamily Porcellioidea (Vetigastropoda) from the richly diverse Lower Devonian gastropod fauna of the Road River Formation in the Royal Creek area, Yukon Territory. This fauna belongs to Western Canada Province of the Old World Realm. The Pragian species Porcellia (Porcellia) yukonensis n. sp. and Porcellia (Paraporcellia) sp. represent the oldest presently known members of subgenera Porcellia (Porcellia) and Porcellia (Paraporcellia). Their simple shell ornamentation fits well with an earlier described evolutionary trend in shell morphology of the Porcellinae. Late Pragian to early Emsian Perryconcha pulchra n. gen. and n. sp. is the first member of the Porcellioidea bearing a row of tremata on adult teleoconch whorls. The occurrence of this shell feature in the Porcellioidea is additional evidence that the evolution of the apertural slit was much more complicated than has been proposed in classical models of Paleozoic gastropod evolution.

Additional Silurian (Ludlovian) gastropods are described from the Heceta Formation in the Alexander terrane on Prince of Wales Island, southeastern Alaska. Species include Spinicharybdis krizi n. sp., Spinicharybdis boucoti n. sp., Morania wagneri n. sp., Haplospira craigi n. sp., Australonema sp., Pachystrophia cf. gotlandica (Lindström,1884), and Medfrazyga gilmulli n. sp. An additional new Silurian species, Morania nixonforkensis n. sp., is described from the Nixon Fork subterrane of the Farewell terrane of west-central Alaska.

The spine-bearing Spinicharybdis is placed into a new subfamily Spinicharybdiinae together with Hystricoceras Jahn, 1894. Joint occurrences of genera Beraunia, Coelocaulus, and Morania, as well as members of subfamily Spinicharybdiinae in the gastropod fauna from the Heceta Formation, support its close relationship with gastropod fauna of Bohemia. Additionally, the occurrence of the genus Medfrazyga suggests a faunal link between the Alexander and Farewell terranes of Alaska. Medfrazyga gilmulli n. sp. is the oldest known and the only early Paleozoic member of the family Palaeozygopleuridae.