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A comprehensive taxonomic account of fourteen ammonite species from the upper Albian succession of the Cauvery Basin, south India is presented. They belong to the genera/subgenera Gaudryceras, Anagaudryceras, Tetragonites, Puzosia (Puzosia), Puzosia (Bhimaites), Desmoceras (Desmoceras), Desmoceras (Pseudouhligella), Stoliczkaia (Stoliczkaia) and the heteromorphs Anisoceras and Mariella. Most of these ammonite species are cosmopolitan and well-known, especially from the western margin of the Tethys. The additional value of this study in contrast to earlier studies is founded in the intensive bed-by-bed collection from a well-documented measured section. This allows to establish a first detailed range chart for the uppermost Albian of this region and to correlate the Cauvery Basin section with the upper Albian Mortoniceras perinflatum Zone-Arrhaphoceras briacensis Zone interval of the Standard Tethyan Scheme.

Late Aptian – early Albian ammonoids of southern Patagonia are described. They are represented by Carinophylloceras collignoni Klinger, Wiedmann and Kennedy, Phyllopachyceras reymenti sp. nov., Tetragonites heterosulcatus Anthula, Anagaudryceras sacya (Forbes), Puzosia cf. rectecostata Collignon and Douvilleiceras mammillatum Schlotheim. T. heterosulcatus Anthula occurs in the Peltocrioceras deeckei Assemblage Zone (≈Jacobi Standard Zone, upper Aptian), and all the other species have been recorded from the lower Albian Aioloceras argentinum and/or Aioloceras rollerii Assemblage Zones (≈Mammillatum Standard Zone, lower Albian). The late Aptian–early Albian ammonoid fauna here described indicates a direct migration route with central Tethys, through southeastern Africa and supports for this time correlation of the Austral faunal region with the European Standard.

Recent biostratigraphic and sedimentologic studies in the lower–mid Campanian ammonite-rich shelf deposits of the James Ross Basin, Antarctica made possible a precise reconstruction of facies tracts along an onshore–offshore transect about 70 km in length. In proximal, inner-shelf settings the Santa Marta Formation include trigoniid-rich coquinas and cross-bedded and massive sandstones. In distal, mid- to outer-shelf settings the age-equivalent Rabot Formation consists of bioturbated mudstones and interbedded inoceramid- and brachiopod-rich tempestites. Each of these sedimentary facies is characterized by a very distinctive ammonite facies, whose characterization along a neritic-oceanic gradient offer clues to ammonite habitats. Ammonite facies of proximal settings are dominated by relatively large and ornate kossmaticeratids, with subordinated heteromorphs, desmoceratids, gaudryceratids and tetragonitids. Taphonomy, size–frequency distribution, and non-lethal injuries attributed to arthropods consistently suggest a shallow habitat and a nektobenthic (demersal) mode of life for the kossmaticeratids. Conversely, in distal settings the ammonite facies is dominated by gaudryceratids, including large Anagaudryceras sp., and tetragonitids, with subordinated small kossmaticeratids and large pachydiscids. Restriction to offshore oceanic-influenced facies suggests that these gaudryceratids have a mesopelagic, planktic mode of life. The hamitocone heteromorphs are equally distributed in shallow and deep facies with a high degree of shell fragmentation, particularly in shallow settings. This pattern suggests that hamitocones were exposed to extensive post-mortem drift. Fil: Olivero, Eduardo Bernardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego; Argentina Fil: Raffi, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego; Argentina

Nine ammonoid species are reported from the Maastrichtian Senpohshi Formation exposed along the western coast of Akkeshi Bay, eastern Hokkaido, and their respective chronologic assignments are discussed on the basis of a previous magnetostratigraphic study. Pachydiscus flexuosus occurs in the lower and middle parts of the formation (= polarity chron C31n, i.e., middle to upper middle Maastrichtian). Gaudryceras makarovense, Anagaudryceras matsumotoi and Diplomoceras cf. notabile and P. flexuosus as well occur in the lower part (middle middle Maastrichtian). The uppermost part of the formation (= probably the lower part of polarity chron C30n, i.e., lower upper Maastrichtian) is fossiliferous and yields a diverse ammonoid assemblage including Neophylloceras sp., Pseudophyllites sp., Zelandites varuna, A. matsumotoi, Gaudryceras cf. seymouriense, Gaudryceras sp., and D. cf. notabile. Integration of bio- and magnetostratigraphy in the Senpohshi Formation makes it possible to determine precise and detailed chronologic assignment of strata containing similar faunas in the Northwest Pacific realm.

We describe an asymmetrical basal delphinoid skull from the upper lower Miocene Yamato Formation of Hokkaido, northern Japan. The skull shows clear cranial asymmetry: the nasal process of the left premaxilla is longer than that of the right one; the mesethmoid and frontals are left skewed 2.9°; and the right nasal is larger than the left one. Evaluation of the deformation of the fossil based on the carbonate content of the matrix indicates that the concretion in which the skull was found formed in an early stage of diagenesis and that the present specimen was not affected by compaction during diagenesis. A cladistic analysis including the new specimen shows cranial asymmetry among Delphinoidea extends back to the late early Miocene in the fossil record, and supports the hypothesis that cranial asymmetry in basal delphinoids is more common than previously thought. On the other hand, trait analyses suggest that the common ancestor of Delphinoidea had a symmetrical skull. We hypothesize that some e...

Anagaudryceras compressum sp. nov., the most slender of this genus, is newly described from the Nostoceras hetonaiense Zone of earliest Maastrichtian age (Late Cretaceous), in the Hobetsu area, Hokkaido, northern Japan. Its shell is fairly small (< 80 mm in diameter) and compressed with a highly arched venter. The last whorl is ornamented with low, broad, gently flexed band-like ribs. Its ornamentation is very similar to A. matsumotoi, thus suggesting a close phylogenetic relationship with this taxon, which is probably its descendant.

Maastrichtian ammonites are described from two areas in Pakistan. The upper part of the lower unit of the Korara Shale in the southern Pab Range, Kirthar Province, southern Balochistan, is dated as Late Maastrichtian, based on the presence ofMenuites fresvillensis(Seunes, 1890), which is accompanied by abundantIndoceras baluchistanenseNoetling, 1897, commonBaculites ambatryensisCollignon, 1971, and rarerNeophylloceras surya(Forbes, 1846),Gaudryceras kayei(Forbes, 1846),Anagaudryceras politissimum(Kossmat, 1895),Kitchinites spenglerin. sp.,Pachydiscus (Pachydiscus) noetlingin. sp.,Libycoceras acutodorsatus(Noetling, 1897), andDiplomoceras cylindraceum(Defrance, 1816). A smaller assemblage from the Mughal Kot Formation near Kach, Suleman Province, northern Balochistan cannot be dated more precisely than Maastrichtian from the presence ofPachydiscus(Pachydiscus)neubergicus(Hauer, 1858), the first occurrence of which has been provisionally adopted by the Subcommission on Cretaceous Stratigraphy as marking the base of the Maastrichtian stage. It is associated with numerousEubaculites binodosus(Noetling, 1897).

Maastrichtian cephalopods and a brachiopod were dredged from the Butakov, Fedorov, Kotsebu, Il’ichev, Govorov, Gelendzhik, and Ita-Mai-Tai guyots in the Magellan Seamounts. The ammonoids Hypophylloceras sp., Phyllopachiceras sp., Anagaudryceras? sp. A, Anagaudryceras? sp. B, Gaudryceras aff. propemite Marshall, Gaudryceras sp., and Pseudophyllites cf. indra (Forbes), and the single brachiopod Basiliolidae gen. and sp. indet. are a first discovery in this oceanic region, following earlier finds of belemnites (Dimitobelus? sp., Dimitobelidae gen. and sp. nov., and Belemnitella? sp.), and two ammonoid species (Zelandites aff. japonicus Matsumoto and Tetragonitidae gen. and sp. indet.). The Late Cretaceous Magellan Seamounts dimitobelid belemnite fauna shows affinities with southern high latitude forms (New Zealand) and the ammonoid fauna with northern, middle and high latitude ones (Hokkaido-Sakhalin and/or Kamchatka). This suggests by the end of the Cretaceous major surface palaeo-currents from S and N sides in direction of the central Palaeo-Pacific, a position coinciding with the plate tectonic reconstruction of the Magellan Seamounts.

The Quiriquina Formation in central Chile is famous for its abundant and diverse ammonite assemblages of Maastrichtian age. In the type locality around the Concepcion Bay in the Bio-Bio Region of central Chile we have identified a total of 30 species referred to 17 genera. Hypophylloceras (Neophylloceras) ramosum, H. (N.) hetonaiense, H. (N.) inflatum, H. (N.) surya, Anagaudryceras politissimum, Gaudryceras kayei, Zelandites varuna, Pseudophyllites indra, Kitchinites darwini, Kossmaticeras (Natalites) erbeni, Grossouvrites gemmatus, Gunnarites spinosissimus, Maorites densicostatus, Pachydiscus (P. ) jacquoti chilensis, Menuites fresvillensis, Diplomoceras cylindraceum, Phylloptychoceras sp., Baculites huenickeni, Baculites vicentei and Eubaculites carinatus have been recorded previously from the Quiriquina Formation. Hoploscaphites constrictus quiriquiniensis sensu WILCKENS (1904). Phyllopachyceras forbesianum, Anagaudryceras subtilineatum, Gunnarites cf. bhavaniformis and Baculites anceps are new records for the Quiriquina Formation added here. Kitchinites vicentensis n. sp., Kitchinites ifrimae n. sp., Grossouvrites joharae n. sp., Pachydiscus (P. ) gutierrezi n. sp. and Menuites gerardoi n. sp. are new. Gaudryceras kayei specimens are recorded with diameters in excess of 200 mm and present marked changes during growth. Anagaudryceras politissimum and Zelandites varuna also show strong ontogenetic changes. Kitchinites darwini of the Quiriquina Formation differs from material from Antarctica; we propose that the latter should by separated. The presence of Hypophylloceras (Neophylloceras) surya, Zelandites varuna, Pachydiscus (P. ) jacquoti, Diplomoceras cylindraceum, Baculites anceps, Eubaculites carinatus and Hoploscaphites constrictus quiriquiniensis indicates a Maastrichtian age for the Quiriquina Formation. Menuites fresvillensis confirms the late Maastrichtian age for most of the Quiriquina Formation. The assemblage presented shows cosmopolitan and Indo-Pacific affinities with a few European and Tethyan links.

Cretaceous sediments of the Yezo Group in the Yezo forearc basin-fill are widely distributed along the meridian zone of Hokkaido, Japan. The uppermost part of the Cretaceous sequence, namely the Hakobuchi Formation, ranges in age from Early Campanian to Late Maastrichtian and partly into Late Paleocene. It is subdivided into, in ascending order, the Kamikoma, Heitaro-zawa, Oku-utsunai and Utsunaigawa members in the Nakatonbetsu area, north Hokkaido. Recently, an unconformable sequence boundary was found between the Heitaro-zawa and Oku-utsunai members. A Lower Campanian and two Lower Maastrichtian inoceramid zones are established in the lower half of the Hakobuchi Formation. A lower Upper Maastrichtian ammonite fauna, composed of Anagaudryceras matsumotoi, Pseudophyllites indura and Zelandites varuna, can be recognized above the inoceramid extinction horizon in the upper Heitaro-zawa Member. Although there are no good index megafossils in the two overlying members, Glycymeris shell-beds of the basal Oku-utsunai Member overlie the Upper Maastrichtian Heitaro-zawa Member with a sharp, undulating, erosional surface. As Late Paleocene nannofossils were reported from the two upper members, the uppermost Maastrichtian and Lower Paleocene appear to have been eroded away at the unconformity. The K/Pg gap can be traced into the Oyubari and north Hobetsu areas of central Hokkaido and four drillholes offshore from Honshu in the Pacific Ocean. This might indicate large-scale subaerial erosion caused by a relative sea-level fall throughout the Yezo Basin.

Sediments of the Mendez Formation near Cerralvo, north-eastern Mexico, yield an abundant and diverse Maastrichtian ammonite assemblage. A total of 23 species referred to 18 genera are described, in addition to the possible coleoid Naefia neogaeia. The assemblage is considered to be of early Maastrichtian age on the basis of ammonite occurrences and has been dated to the lower Maastrichtian biozone CF 7 by planktic foraminifera. None of the ammonite species has been reported previously from the Mendez Formation and most species are recorded from Mexico for the first time. In addition to faunal elements known from other Gulf of Mexico localities [Baculites ovatus, Nostoceras (N.) alternatum, N. (N.) colubriformis, N. (N.) rugosum, Solenoceras reesidei] the assemblage is characterized by cosmopolitan (e.g. Anagaudryceras politissimum, Desmophyllites diphylloides, Diplomoceras cylindraceum, Gaudryceras kayei, Phyllopachyceras forbesianum, and Pseudophyllites indra) and Tethyan elements [e.g. Brahmaites (Anabrahmaites) vishnu, Fresvillia constricta, Hauericeras rembda, Solenoceras texanum, Tetragonites superstes]. Some ammonite species have been known from the Indopacific region a [e.g. Fresvillia aff. F. teres, Neophylloceras (Hypophylloceras) hetonaiense, Zelandites varuna] and are clearly cold-water species. The composition of the assemblage contrasts with other Gulf of Mexico faunas which is related to bathymetry.

The first record of the Albian ammonite Aioloceras is documented from the Kotick Point Formation, James Ross Island, northern Antarctic Peninsula. The material is identified with the type species, Aioloceras argentinum (Bonarelli, 1921), previously only known from southern Patagonia. It is associated with Desmoceras sp., Anagaudryceras sp., Parasilesites sp., Rossalites sp. and Phyllopachyceras sp. On the basis of this assemblage, the presence of the Aioloceras argentinum Assemblage Zone from Patagonia, which is considered coeval to the upper lower Albian Mammillatum Superzone, is extended to Antarctica.

Tanabe, K., Landman, N.H. & Kruta, I. 2011: Microstructure and mineralogy of the outer calcareous layer in the lower jaws of Cretaceous Tetragonitoidea and Desmoceratoidea (Ammonoidea). Lethaia, Vol. 45, pp. 191–199. Based on the differences in their relative size, overall shape, structure and the degree of development of an outer calcified covering, lower jaws of the Ammonoidea have been classified into four morphotypes: normal, anaptychus, aptychus and rhynchaptychus types. However, detailed microstructural and mineralogical comparison of these morphotypes has not yet been addressed. This article documents the results of SEM and XRD observations of the lower jaws of three Late Cretaceous ammonoid species belonging to the Tetragonitoidea (Anagaudryceras limatum) and Desmoceratoidea (Pachydiscus kamishakensis and Damesites aff. sugata), based on excellent material preserved in situ within the body chamber, and retaining an aragonitic shell wall. The lower jaws of the three species are assigned to an intermediate form between anaptychus and aptychus types for the first two species and the rhynchaptychus type for the third species. Their black, presumably originally chitinous outer lamella is wholly covered with a calcareous layer. The calcareous layer is composed of aragonite in D. aff. sugata and A. limatum, and calcite in P. kamishakensis. The microstructure of the outer calcareous layer differs among the three species, i.e. granular in A. limatum, spherulitic prismatic in D. sugata, and prismatic in P. kamishakensis, all of which can be distinguished from the lamellar and spongy structure of the outer-paired calcitic plates of the typical aptychus-type lower jaws in some Jurassic and Cretaceous Ammonitina and Ancyloceratina. Our study suggests that most Jurassic and Cretaceous ammonoids possessed an outer calcareous layer in their lower jaws, although its mineralogy, microstructure and relative thickness vary among different taxa. □Ammonoidea, Cretaceous, Desmoceratoidea, lower jaw, microstructure, Tetragonitoidea.

The stratigraphy of Cretaceous marine mudstones in the Fuegian Andes, roughly equivalent to Charles Darwin's clay-slate formation, remains a still unsolved problem. Previous records of Albian, Turonian-Coniacian, and Santonian-Campanian bivalves are combined with new findings of the Late Albian inoceramid Inoceramus anglicus Woods, and the Maastrichtian ammonites Diplomoceras sp., Anagaudryceras sp., Maorites densicostatus (Kilian and Reboul), Maorites sp., and Pachydiscus (Neodesmoceras) sp. to further constrain the Cretaceous stratigraphy of the eastern Fuegian Andes. In addition, new records of distinctive trace fossils and ichnofabric are meaningful for stratigraphic division and delineation of paleoenvironmental settings in these Cretaceous mudstones. The Lower Cretaceous ichnoassemblage of Chondrites targioni (Brongniart) and Zoophycos isp. is consistent with the inferred slope-volcaniclastic apron settings of the Yahgan Formation; Nereites missouriensis (Weller) reflects distal basin plain depositional settings for the Beauvoir Formation. In the Upper Cretaceous, the "Estratos de Buen Suceso" record the earliest extensively bioturbated horizons, reflecting prolonged well-oxygenated bottom conditions. In the Bahía Thetis Formation, organic-rich, channel margin or distal basin slaty mudstones record the last occurrence of inoceramid bivalves in the Austral Basin; the generalized absence of trace fossils is consistent with dysoxic bottom conditions. The thoroughly bioturbated Policarpo Formation, records a marked change in paleoceanographic conditions. The strong contrast in the intensity of bioturbation between the Upper Campanian-Maastrichtian Bahía Thetis Formation, almost devoid of trace fossils, and the highly bioturbated Maastrichtian-Danian Policarpo Formation reflects a change from dysoxic-anoxic to well ventilated conditions, probably associated with a cooling trend of bottom waters in the austral deep oceans. Fil:Olivero, E.B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Medina, F.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

One of the richest and best preserved late Campanian-Maastrichtian ammonite faunas of the world occurs within the Lopez de Bertodano Formation on Seymour Island. The excellent exposure of this sequence has offered an opportunity for detailed stratigraphic study of the fauna, providing a stratigraphic control unavailable for most other Southern Hemisphere strata of similar age.Ammonites are restricted to the Cretaceous portion of the Lopez de Bertodano Formation, becoming more abundant and increasing in diversity within a 600-m interval below the Cretaceous-Tertiary boundary. The ammonite-rich levels are divided into three zones (from oldest to youngest:Pachydiscus ootacodensis, P. riccardiandP. ultimuszones), extending from the late Campanian-Maastrichtian to the latest Maastrichtian.The taxonomic study of this fauna shows a predominance of endemic taxa of the family Kossmaticeratidae, including the speciesMaorites tuberculatusHowarth,M. seymourianus(Kilian and Reboul),M. densicostatus(Kilian and Reboul),M. weddelliensisn. sp.,Grossouvrites gemmatus(Huppe) andGunnarites bhavaniformis(Kilian and Reboul). These taxa, together with the members of the family DesmoceratidaeKitchinites(Kitchinites)darwini(Steinmann) andK.(K.)lauraen. sp., are mostly restricted to the margins of the Late Cretaceous Weddellian Province that extended from southern South America to Australia.Cosmopolitan genera described in this work become more abundant up section and include the speciesAnagaudryceras seymouriensen. sp.,Zelandites varuna(Forbes),Pseudophyllites loryi(Kilian and Reboul),Diplomoceras lambiSpath,Pachydiscus(Pachydiscus)ootacodensis(Stoliczka),P.(P.)riccardin. sp. andP.(P.)ultimusn. sp.

A complete taxonomic survey of ammonites from the Clarence and Raukumara Series (Albian-?Santonian) is presented. Eleven new species, Anagaudryceras woodsi, Hamites (Hamites) kaiwhataensis, Turrilites (Turrilites) exutus, Hypoturrilites varians, Mariella (Mariella) thomsoni, Scaphites wellmani, S. vellai, Worthoceras parvum, W. costatum, W. johnstoni and Puzosia (Puzosia) bushgrovenis and a new subspecies, Scaphites equalis coverhamensis are erected. Anisoceras, Ammonoceratites, Idiohamites, Worthoceras, and authentic Hamites and Turrilites are recorded from New Zealand for the first time. New Zealand species of Worthoceras throw new light on the phylogenetic significance of this genus. Two formal ammonite zones, the Worthoceras parvum Assemblage Zone (lower Ngaterian) and the Scaphites equalis coverhamensis Assemblage Zone (upper Ngaterian) are established. Continued submersion of the Coverian Stage within the Ngaterian is advocated in spite of its distinctive ammonite assemblage. Relationships ...

Genus Nautilus, Linnaeus. There are four well-marked species of this genus in the collection. Two of them appear to be identical with European species, and two are new. The former are cretaceous forms: of the latter, one is nearly allied to a cretaceous and the other to oolitic species. Not one of the specimens is in perfectly good condition, so that the certainty of the determinations may hereafter be questioned. I. Nautilus laevigatus , D’Orbigny? N. testâ subglobosâ, inflatâ, laevigatâ, subumbilicatâ; aperturâ orbiculari-lunatâ; septis obsolete undulatis; siphunculo subcentrali. Median diameter, 6 inches. Breadth at base of aperture, 4 inches. Shell subglobose, much-inflated, slightly umbilicated, externally smooth; the mouth suborbicular and lunate. The chambers have a slight tendency to show a sinuated outline. The siphon is a little nearer to the spire than to the back. The spaces between the chambers and the degree of inflation of the entire shell vary in different specimens. Young examples have a very smooth shell. I cannot distinguish it from the Nautilus laevigatus, except in that the chambers of the French species are usually wider. M. D’Orbigny describes his shell as from the “ couches moyennes de la craie, a 1’etage des craies tufau et au gres vert.” (D’Orb. P. F. Terrains Cretaces, vol. i. p. 84. pi. 17.) Locality, Pondicherry. 2. Nautilus sphaericus , sp. nov. N. testâ globosâ inflatissimâ (laevigata ?), umbilicatâ; aperturâ latissimâ, hinatâ, angustatâ; septis arcuatis; siphunculo excentrico. Median diameter, 4 inches. A very