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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 Vasicek, 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.

The Agrio Formation of the Neuquen Basin, Argentina, contains an extensive sequence of ammonite faunas, most of which are monogeneric. Detailed collecting through 15 sections across the basin has facilitated a major revision of the ammonite zonation. Formerly embracing four broad zones, the Agrio Formation is now divided into nine zones, the lowest four of which are divided into a total of 11 subzones. The new zonation provides a standard against which other South American faunas can be compared. The degree of subdivision now achieved is comparable to that for the 'standard' sequences of the West Mediterranean region. Although it is not possible to correlate the two regions in detail, the occurrence of some widely distributed genera (Olcostephanus, Karakaschiceras, Oosterella, Spitidiscus and Crioceratites) at well-defined levels in the Neuquen Basin provides some crucial links. Thus the approximate positions of the Lower/Upper Valanginian, Valanginian/Hauterivian and Lower/Upper Hauterivian boundaries can be determined.

A new genus and species of heteroceratid ammonite from the Barremian of California has been identified. The type specimens are differentiated from other known members of Heteroceratidae by the rate of whorl expansion of the conch cross-section, the orientation of the spire axis with respect to the planispiral portion of the conch axis and ornamentation.

The Early Permian (late Sakmarian to early Artinskian) adrianitid ammonoid Nevadoceras steelei new genus and species occurs in a fauna containing the ammonoids Properrinites Elias, Prothalassoceras Bose, Daraelites Gemmellaro, Almites Toumanskaya, Bamyaniceras Termier and Termier, Akmilleria Ruzhencev, Agathiceras Gemmellaro, Metalegoceras Schindewolf, Stenolobulites Mikesh, Glenister, and Furnish, Crimites Toumanskaya, Neocrimites Ruzhencev and the conodonts Sweetognathus whitei (Rhodes) and Mesogondolella bisselli (Clark and Behnken). This fauna occurs in a concretionary interval within micritic basinal facies of the Dry Mountain trough at Portuguese Springs, White Pine County, east-central Nevada.

Shell shape varies within many ammonoid species, and some ammonoid lineages appear to have evolved in concert with changes in their environment. We report variation within an Upper Cretaceous ammonoid species that correlates with facies differences and is consistent with a hydrodynamic explanation. In the Turner Sandy Member of the Carlile Shale (Turonian) of South Dakota and Wyoming, more compressed morphs of Scaphites whitfieldi Cobban are found in nearshore sandy facies, whereas more depressed morphs occur in offshore muds. We measured drag forces on models of juvenile and adult shells that differed in lateral compression of the shell. Plots of drag coefficient as a function of Reynolds number indicate that thinner, more compressed morphs swam more efficiently at higher velocities and depressed morphs swam more efficiently at low velocities. Higher swimming velocities may be essential for life in nearshore sandy environments, which have higher ambient current velocities. Shelled cephalopods swim most efficiently at low swimming speeds; therefore, lower velocity, more energetically economical swimming should be preferred in more quiescent offshore settings. An analysis of power consumption supports this interpretation. Correlated changes in shell compression and environmental factors, here observed within a species, have been documented in numerous ammonite lineages. These iterative evolutionary changes within lineages may be similarly explained by selection for shell morphologies appropriate to environments that fluctuate cyclically with sea level.

Representatives of the ancestral cyclolobin ammonoid Demarezites Ruzhencev (Cyclolobidae) are known from only a few localities in North America where they occur as rare faunal elements. Demarezites furnishi n. sp. is based on a single specimen from 'Middle' Permian (Roadian) strata in the Meade Peak Member of the Phosphoria Formation in eastern Idaho. Several specimens of the closely comparable Demarezites n. sp., described herein, are known from the Pipeline Shale Member of the Brushy Canyon Formation in West Texas.

Reticuloceras (Swintoceras) n. subgen. unites an early group of the mid-Carboniferous goniatite family Reticulocertidae, in which reticulate sculpture is weakly developed or lacking and the typically reticuloceratid suture has slightly expanded ventral prongs. The type species, Reticuloceras (S.) spiraloides (Bisat and Hudson, 1943), is a rare, poorly known species from the British Namurian. Two additional species, R. (S.) wainwrighti (Quinn, 1966) and R. (S.) tiro (Gordon, 1969), are common in the basal type Morrowan Series, Lower Pennsylvanian, of Arkansas. Swintoceras occurs with two distinctive, late forms of the ammonoid, Hudsonoceras: Hd. ornatum (Foord and Crick, 1897) in Britain and Hd. moorei Quinn and Saunders, 1968, in Arkansas. The co-occurrence of these taxa correlates the basal Morrowan in its type region with the Namurian Reticuloceras nodosum (R(sub 1b)) Zone of Britain and thereby also dates the close of the Mid-Carboniferous Eustatic Event in the North American Midcontinent.

The Saratoga Chalk of Arkansas yields a rich ammonite fauna of 17 species, referred to the Nostoceras (N.) hyatti zone. Recognition that the northwest European N. (N.) pozaryskii Blaszkiewicz, 1980, is a synonym of N. (N.) hyatti Stephenson, 1941, and N. (N.) helicinum (Shumard, 1861) dates the zone as latest Campanian on the basis of co-occurrence with Belemnitella langei Jeletzky, 1948, in Poland. Most previous estimates of the Campanian-Maastrichtian boundary in the Gulf Coast have been drawn at too low a level, at least in terms of ammonite faunas. Elements of the N. (N.) hyatti zone fauna occur in the United States Western Interior, and show the base of the Maastrichtian there to lie above the Baculites jenseni zone.

Questions on the validity of Alteceras originate from a lack of completely preserved material. However, a Queensland Museum specimen of the type species Myloceras (Alteceras) has helped to dispel this doubt. Fossil analysis suggests a mudstone Allaru Formation origin although other fragmented specimens suggest Toolebuc origins. It is generally accepted that Myloceras (Aleteceras) includes three species: M. (A.) andinus, M. (A.) nautiloides and M. (A.) plectoides.