The holotype of Diplodocus carnegii Hatcher, 1901, consists of a partial skeleton (CM 84) that was recovered, along with a second partial skeleton of the same species (CM 94), from the upper 10 m of the Talking Rock facies of the Brushy Basin Member of the Morrison Formation exposed along Bone Quarry Draw, a tributary of Sheep Creek in Albany County, Wyoming. A composite measured section of the stratigraphic interval exposed adjacent to the quarry indicates that the Brushy Basin Member in this area is a stacked succession of lithofacies consisting of hackly, greenish gray, calcareous mudstone and greenish brown, dense, fine-grained limestone. The more erosion resistant limestone layers can be traced over many hundreds of meters. Thus, these strata do not appear to represent a highly localized deposit such as a stream channel, oxbow lake, or backwater pond. The Sheep Creek succession is interpreted as representing a clastic-dominated lake where high turbidity and sediment influx produced deposition of calcareous mudstone. During drier periods the lake's turbidity decreased and limestone and dolomite precipitation replaced mud deposition. Microkarsting at the top of some limestone/dolomite layers suggests subaerial deposition may have prevailed during these dry episodes.

The quarry of D. carnegii was excavated within the top strata of one of the numerous intervals of hackly, greenish gray, calcareous mudstone that represent an ephemeral freshwater lake. The quarry strata are directly overlain by 0.3 m of dolomite-capped limestone that was deposited shortly after interment of D. carnegii in the lake mudstones. The close vertical proximity of the overlying limestone to the skeleton's stratigraphic level suggests that the animal's carcass may have been buried beneath the drying lake deposits during a period of decreased rainfall.

Described from the Wymps Gap Member of the Mauch Chunk Formation of southwestern Pennsylvania and adjacent Maryland is a new species, Phyricodothyris lauriegrahamae, of the Upper Mississippian reticulariod brachiopod Phyricodothyris George, 1932. The Wymps Gap Limestone from which the type material was collected is middle Chesterian (late Viséan) in age. This is the first report of this genus from confirmed Mississippian rocks in North America.

Four exposed planar surfaces within the type area of the Monte León Formation (early Miocene) of southern Patagonia, Argentina, enclose significantly different fossil assemblages positioned in close geographic and stratigraphic proximity to one another. The exposed paleosurfaces were mapped in planar view using a quadrat grid system. Precise fossil position and orientation data, stable isotope thermometry and petrographic analyses, and petrologic and taphonomic evidence suggest an inner-shelf, shallow water habitat, above storm wave base, with a well-oxygenated benthos and weak offshore bottom currents. The rate of sedimentation was generally low, interspersed with periods of non-deposition and sporadic, higher-energy pulses of sediment input. Stable isotope analyses of foraminiferans indicate bottom water temperatures consistent with a modern mid-latitude coastal setting. Two distinctly different assemblages were observed: 1) a relatively diverse, normal marine benthic fauna consisting of bivalves, gastropods, bryozoans, echinoids, and decapods; and 2) a unique assemblage consisting solely of numerous, exceptionally preserved, fully-articulated crabs. These assemblages occur in a one meter interval within the lower-most beds of the Monte León Formation. The occurrence and preservation of large numbers of decapods within the fossil record are rare, making these deposits remarkable. The crab-rich assemblage was stratigraphically positioned below the surfaces containing the normal marine assemblage. The crabs are contained within a slightly compacted, argillaceous volcanic tuff, consisting mostly of volcanic glass shards and euhedral plagioclase grains. Biogenic fragments are noticeably absent from the deposit, unlike sediments collected from the upper surfaces. Most of the crabs were preserved with their third maxillipeds in an open, gaping posture. This is consistent with postures observed in extant crabs suffering from respiratory distress. From the above evidence it is inferred that the fossil crabs were suffocated, killed, and rapidly buried. Supradjacent layers record the re-establishment of normal marine conditions. The apparent faunal disparity observed on the four paleosurfaces within the Monte León Formation is interpreted as representing the initial decimation and eventual re-establishment of the benthic marine fauna following a catastrophic volcanic event.

The extant species of fleas in the North American ceratophylline genus Malaraeus Jordan, 1933, are reviewed and redescribed. Malaraeus sinomus (Jordan, 1925) is considered to be a junior synonym of Malaraeus eremicus (Baker, 1904). The second species, Malaraeus telchinus (Rothschild, 1905), is the commonest member of the genus. Traubella grundmanni Egoscue, 1989, is treated as a third species of Malaraeus. A key to the species is provided and the diagnostic characters of the three taxa are illustrated.

The biology and immature stages of snail-killing flies (Diptera: Sciomzyidae) that are predators on land snails and slugs are presented, including the geographic distribution, habitat occurrence, life cycle, and larval feeding habits of three species of Tetanocera Duméril preying on slugs (Tetanocera clara Loew, Tetanocera plebeja Loew, and Tetanocera valida Loew), and one species attacking land snails (Tetanocera phyllophora Melander).

The two North American species of the ceratophylline flea genus Amalaraeus Ioff, 1936, A. dissimilis (Jordan, 1938) and A. dobbsi (Hubbard, 1940), are discussed in light of our current knowledge of their distribution and host preferences. A key and distribution maps are included, as well as a detailed history of the nomenclature of the two taxa.