Ammonite Fauna Research Articles

A new ammonoid fauna from theGattendorfia-Eocanites Genozone of the Anti-Atlas (Early Carboniferous; Morocco)

From the eastern part of the Tafilalt (Anti-Atlas, Morocco), rich assemblages of ammonoids of the Gattendorfia-Eocanites Genozone are described. The detailed investigation of an outcrop near Mfis in the south-eastern Tafilalt yielded a diverse fauna with 24 species, of which 13 are new. The genus Weyerella n. gen. is newly erected with Weyerella protecta n. sp. as type species. Furthermore, the following new species are described: Paragattendorfia aboussalamae n. sp., Acutimitoceras hollardi n. sp., Acutimitoceras posterum n. sp., Acutimitoceras mfisense n. sp., Acutimitoceras occidentale n. sp., Imitoceras oxydentale n. sp., Kazakhstania nitida n. sp., Zadelsdorfia debouaaensis n. sp., Weyerella minor n. sp., Eocanites simplex n. sp., Eocanites rtbeckeri n. sp., and Eocanites dkorni n. sp. The state of preservation of the ammonoids as limonitic steinkern specimens permits a detailed study of sutures and conch ontogeny.

Stratigraphy, facies analysis and ammonite fauna of the Qal'eh Dokhtar Formation (Middle - Upper Jurassic) at the type locality west of Boshrouyeh (east-central Iran).

Stratigraphy, facies analysis and ammonite fauna of the Qal'eh Dokhtar Formation (Middle - Upper Jurassic) at the type locality west of Boshrouyeh (east-central Iran).

John Michael (‘Jake’) Hancock (1928–2004): a personal memoir

This is a personal memoir of my teacher, supervisor, colleague, collaborator and friend, Jake Hancock. He was a geological institution (as the publication of this part of the Proceedings demonstrates). Jake was born in Salisbury, Wiltshire, where he grew up. Education was interrupted by National Service between 1947 and 1949, after which he went up to Queen's College Cambridge. Awarded a BA in geology with petrology in 1952, he stayed on at Cambridge, working for his doctorate under the supervision of Maurice Black (1904–1973). The subject was the marginal facies of the British Chalk. The interests of Black and of Joscelyn Arkell (1904–1958) were to be reflected in his subsequent research career. Appointed to an Assistant Lectureship at King's College, London in 1955, he rose to Reader in 1977. With the closure of the King's department, he eventually joined Imperial College, London in 1986, with a professorship. Following retirement in 1993, he continued to teach at Imperial until his death in 2004. Jake's research output runs to over 100 articles on Cretaceous stratigraphy and sedimentation, palaeogeography, sea-levels, ammonite faunas, biostratigraphy and correlation. The deposition and diagenesis of the Chalk was a major preoccupation, both as curiosity-driven research and as a consultant to the North Sea hydrocarbon industry. In his later years, the link between geology and wine occupied much of his time. He was awarded the Lyell Medal of the Geological Society of London in 1989. His services to geology included a spell as President of the Geologists' Association between 1987 and 1989. Beyond this, he was a kind and generous man, a great eccentric, and a much-loved member of that invisible international college to which we geologists belong.

The stratigraphy of the Inferior Oolite at South Main Road Quarry, Dundry, Avon

A new section opened on the site of the former South Main Road Quarry, Dundry, Avon, is described. The biostratigraphy of the ammonite succession has been revised through careful bed-by-bed collecting and is presented in a range chart. It is recast in the form of a sequence of discrete ammonite fauna! horizons as has become customary in the classical areas of Somerset and Dorset first described in this way by Buckman. One new ammonite faunal horizon has been identified in the Lower Bajocian: Bj-10b, Sonninia micracanthica (Buckman). This carries several of what have been regarded in the past as leading guide-fossils of the Sauzei Zone. But it is now seen to be also the type horizon of the index of the Laeviuscula Zone, Witchellia laeviuscula. It is therefore retained in the Laeviuscula Zone as its youngest horizon on grounds of nomenclatural stability. The basal boundary of the overlying Sauzei Zone is drawn above it and its lowest ammonite horizon renamed, Bj-11a, Stephanoceras kalum (Buckman). The systematics of some important species based on types from Dundry are reviewed briefly and the origins and phylogeny of some important ammonite genera of the Ovale to Sauzei Zones are discussed. The succession of forms of Witchellia is now separated as a phyletic subfamily Witchelliinae subf. nov. within the polyphyletic clade of the Sonniniidae. A new species of Emileia, E. dundriensis, is described from the Laeviuscula Zone. The nautiloids are also reviewed briefly.

Ammonites at the Cenomanian–Turonian boundary in the Sergipe Basin, Brazil

Two distinctive ammonite faunas are described from the Cenomanian–Turonian boundary interval in the Sergipe Basin, Brazil. The Jardim 1 section assemblage comprises Euomphaloceras costatum Cobban, Hook & Kennedy, 1989, Burroceras transitorium Cobban, Hook & Kennedy, 1989, Pseudaspidoceras pseudonodosoides Choffat, 1898, and Vascoceras cf. gamai Choffat, 1898. This same association is found in New Mexico, where it occurs with the upper Cenomanian index fossil Neocardioceras juddii (Barrois & Guerne, 1898). On this basis the Sergipe assemblage is referred to the N. juddii Zone, and correlated with beds 79–84 of the Pueblo, Colorado section. These lie 1.14–0.63 m below the Global boundary Stratotype Section and Point (GSSP) for the base of the Turonian Stage, the base of bed 86, which corresponds to the first occurrence of the ammonite Watinoceras devonense Wright & Kennedy, 1981. The Japaratuba 16 locality in Sergipe yielded an assemblage of Pachydesmoceras kossmati Matsumoto, 1987, Watinoceras coloradoense (Henderson, 1908), Pseudaspidoceras flexuosum Powell, 1963, Pseudovascoceras nigeriense (Woods, 1911), Vascoceras globosum globosum (Reyment, 1954), V. simplex (Barber, 1957), and Pseudotissotia nigeriensis (Woods, 1911). The co-occurrence of W. coloradoense and P. flexuosum is also found in the Pueblo section, in bed 97, 1.65 m above the base of the Turonian. These ammonite records thus allow the placement of the Cenomanian–Turonian boundary in the Sergipe-Alagoas Basin, and correlation with the Global Boundary Stratotype Section and Point at Pueblo.

The youngest Maastrichtian ammonite faunas from Poland and their dating by scaphitids

The youngest Maastrichtian ammonite faunas from Poland are discussed in terms of their taxonomic composition, dating and significance for the end-Cretaceous extinction debate. The fauna from the top of the classic Upper Maastrichtian succession at Nasiłów comprises Baculites spp. (including B. anceps), Hoploscaphites constrictus subsp. A, Menuites terminus, Pachydiscus jacquoti and Sphenodiscus binckhorsti. The commonest components of this fauna, i.e. Baculites spp. and H. constrictus subsp. A, occur also at the top of the Maastrichtian at Bochotnica, Prawiedniki, Mętów and Klimusin. A distinctive fauna, identified for the first time in Poland, is present at the top of the Upper Maastrichtian at Mełgiew. It is composed of H. constrictus subsp. B and Baculites sp. In the standard Upper Maastrichtian Boreal succession at Stevns Klint, Denmark, H. constrictus subsp. A is present in the white chalk and is replaced by H. constrictus subsp. B in the overlying Grey Chalk. Details of the evolutionary succession of H. constrictus as recorded at Stevns Klint allow for relative dating of the ammonite occurrences in Poland. The youngest ammonite faunas from Nasiłów, Bochotnica, Prawiedniki, Mętów and Klimusin, which include H. constrictus subsp. A are considered to be older than the ammonite fauna from the Grey Chalk in Denmark. In contrast, the topmost Maastrichtian fauna from Mełgiew, with H. constrictus subsp. B, is thought to be coeval with that from the top of the Grey Chalk. The abundant occurrence of ammonite specimens at the top of the Maastrichtian successions at Stevns Klint and Mełgiew supports some earlier views that the Boreal ammonites did not suffer any perturbations immediately prior to the end of the Cretaceous.

Toarcian and Aalenian (Jurassic) ammonites from the Shemshak Formation of the Jajarm area (eastern Alborz, Iran)

In the Jajarm area (eastern Alborz Mountains, NE Iran) the ?Upper Triassic — Lower Bajocian siliciclastic Shemshak Formation is up to 2000 m thick. Whereas the lower third of the formation is nearly exclusively non-marine, the upper two-thirds are fully marine. The middle part is characterized by several levels containing a relatively diverse and well preserved assemblage of ammonites of the Toarcian to Aalenian stages. Two sections of the ammonite-bearing strata, spaced 20 km, are presented and correlated by means of ammonite biostratigraphy. The ammonite fauna consists of 27 taxa, some of which are recorded for the first time from the Alborz Mountains. The ammonites are briefly described and their palaeobiogeographic context is reviewed. The ammonite fauna of the Shemshak Formation at Jajarm, as elsewhere in North and Central Iran, is exclusively Northwestern Tethyan in character and is closely related to the faunas of Northwestern and Central Europe.

Les ammonites pliensbachiennes des nappes Lyciennes (Turquie méridionale). Description de faunes nouvelles, implications biostratigraphiques et paléobiogéographiques

This is the first description of Pliensbachian (Carixian and mainly Domerian) ammonite faunas from southern Turkey (Lycian Allochton, western Taurus). These faunas are from the Kısılka-Çorak unit (Kızılca locality, Tavas area) and from the Gümüslü unit (Ayıburnu Tepe and Kuru Dag localities). They consist of 32 species characterising seven biostratigraphic levels. Two new Carixian species are described: Lytoceras kisilcus nov. sp. and Fuciniceras lycius nov. sp. These Lycian faunas chiefly include Juraphyllitidae, Lytoceratoidea, Dactylioceratidae and Hildoceratidae. Conversely, Phylloceratidae are rather scarce. The faunas form a homogeneous assemblage of Mediterranean taxa clearly indicative of a South Tethyan paleobiogeographic affinity. The palaeobiogeographical analysis suggests for the Lycian Pliensbachian deposits a single area of sedimentation protected from oceanic influences by neritic barriers, possibly a basin between the Menderes and the Bey Dagları neritic platforms.

Ammonoid biostratigraphy of the Middle Triassic Latemar platform (Dolomites, Italy) and its correlation with Nevada and Canada

An extensive study of the ammonoid fauna occurring in the lagoonal facies of a Middle Triassic isolated carbonate platform (Latemar platform, Dolomites, Italy) has been undertaken, and ammonoids from selected coeval successions (Punta Zonia, Marmolada, Rio Sacuz) have been illustrated. Ammonoids from Latemar have been collected in 20 distinct horizons (storm deposits) within the ca. 500 m thick lagoonal succession of the platform, thus providing a biostratigraphy of a series which is unusually expanded for this time interval, close to the Anisian–Ladinian boundary. Contrary to general opinion, some ammonoids of the Latemar and other coeval carbonate platforms of the Dolomites (Marmolada, Cernera), in particular Aplococeras avisianum, Lecanites misanii, Celtites spp., and Paranevadites sp., are also present in nearby basinal series. The same taxa have been found in North American localities deposited at the opposite margin of Panthalassa. The homotaxis of these ammonoids in North America and Latemar allow to establish a global scale correlation between the Southern Alps and North America with the highest resolution to date possible. In the context of this study, Aplococeras transiens n. sp. and Esinoceras nerinae n. sp are established.

Biotic changes linked to a minor anoxic event (Faraoni Level, latest Hauterivian, Early Cretaceous)

A conspicuous renewal in the ammonite faunas of the Mediterranean Tethys occurred in the latest Hauterivian. This faunal turnover took place following a stepwise pattern. The first step occurred at the boundary between the Pseudothurmannia ohmi Subzone and the Pseudothurmannia mortilleti Subzone, coinciding with the base of the so-called Faraoni Level. This is a C org-rich interval that has been recognised in several basins of the Mediterranean Tethys and seems to be the expression of a short-lived oxygen-deficient event. It correlates with a well-documented second-order peak transgression. The oxygen depletion preferentially affected the deep nektic ammonites, which would explain the extinctions within this group around the Faraoni Level. On the contrary, an increase in the trophic resources in the photic zone favoured the diversification of epipelagic ammonites. Concurrently, an abrupt change took place at this level in the nannoconid assemblage composition. A minor second event, located at the base of the Pseudothurmannia picteti Subzone, was marked by the replacement of a few planktic ammonite species by closely related forms, and the structure of the ammonite assemblage was not substantially altered. The coincidence of this event with a further restructuring of the calcareous nannofossil assemblage suggests that some changes had to occur in the planktic ecosystem during the sea-level highstand subsequent to the peak transgression. The third and last stage of the renewal process started in the upper part of the P. picteti Subzone, coinciding with a drastic sea-level fall. It is characterised by the extinction of many of the species that had appeared in the two previous events, resulting in an extensive modification of the assemblage structure. The regression would probably cause a drop in the primary productivity and, consequently, an improvement in the oxygenation level of the sea bottom. This would explain the extinction of several planktic ammonite species and the appearance of new nektic and nektobenthic lineages.

Upper Albian and Lower Cenomanian ammonites from the Main Street Limestone, Grayson Marl and Del Rio Clay in northeast Texas

The ammonite faunas of the Main Street Limestone, Grayson Marl and Del Rio Clay form the basis for a revised upper Upper Albian to lower Lower Cenomanian zonal sequence in northeast Texas. A Mortoniceras ( Subschloenbachia) rostratum Zone, previously known to be well-represented in the Denton Clay, Weno Limestone, and Pawpaw Shale, extends into the lower Main Street Limestone. A M. ( S.) perinflatum Zone is also recognised in the Main Street on the basis of the occurrence of the index species, although precise stratigraphic relations of the scattered records of the two index species are not known. The succeeding Mariella ( Wintonia) brazoensis Zone is an Acme Zone, yielding a monospecific assemblage of the zonal index that is abundant in the Main Street Limestone, although the index species ranges both lower and higher in the sequence. The base of the Cenomanian, in ammonite terms, is drawn at the base of the succeeding Graysonites adkinsi Zone, on the basis of the first occurrence of Mantelliceratinae with inner and outer ventrolateral tubercles. The index species of the succeeding G. wacoensis Zone is the senior synonym of Graysonites lozoi Young, 1958, and G. wooldridgei Young, 1958. The Lower Cenomanian sequence is generally truncated by the erosive base of the terrigenous-clastic Woodbine Formation in the study area, but relics of Buda Limestone, and of Grayson Marl with ammonites of the upper Lower Cenomanian Budaiceras hyatti Zone are present locally in Denton and Grayson Counties. A total of 30 ammonite species are described, of which Moremanoceras flexuosum, Stoliczkaia ( Stoliczkaia) conlini, and Neophlycticeras ( Neophlycticeras) fascicostatum are new.

ALBIAN AMMONITE FAUNAS FROM PERU: THE GENUS NEODESHAYESITES CASEY, 1964

Our understanding of the Cretaceous ammonite succession of Peru is mainly based on the reference work of Benavides Caceres (1956) that updates the descriptive paleontological papers by Gabb (1877), Sommermeier (1910), and Knechtel et al. (1947), among others. New fossil collections made in the course 1995 and 1999 in northern and central Peru provide the basis for a revision of the Albian ammonite faunas of this country. In contrast to our predecessors, our collections are based on sections that have been sampled bed by bed. The present study concentrates on the Early Albian ammonites from the Inca Formation of northern Peru. These forms were previously described as Parahoplites nicholsoni Benavides Caceres, 1956, P. inti Benavides Caceres, 1956, and P. quilla Benavides Caceres, 1956. Comparison of the Peruvian specimens with material from Colombia has convinced us that these taxa should be placed in Neodeshayesites Casey, 1964. As interpreted herein, Neodeshayesites is a representative of Acanthohoplitinae that also includes species from Texas previously assigned to Hypacanthoplites Spath, 1923 and Parahoplites Anthula, 1899 (Scott, 1940; Young, 1974). The paleogeographic distribution of the genus is restricted to the New World and includes Colombia, Venezuela, Texas, and Peru. The newly collected Neodeshayesites come from the Banos del Inca and Tamberia Oeste sections in the department of Cajamarca in northern Peru. The first section is situated north of Banos del Inca, 10 km east of the city of Cajamarca, in the direction of Quebrada Otuzco. The second lies northwest of Algodon, near the Hacienda Tamberia, 20 km west of Aguas Calientes and near the junction of the Cajamarca and Crisnejas rivers (Fig. 1). Figure 1 —Map of geographic positions of the Banos del Inca and Tamberia Oeste localities. Details extracted from the 1/250,000 Topographic Map of …

Middle Permian ammonoids from the Kamiyasse-Imo district in the Southern Kitakami Massif, Northeast Japan

ABSTRACT Middle Permian ammonoid faunas are recognized from the Hosoo and Kamiyasse Formations in the Kamiyasse-Imo district, north of Kesennuma, Southern Kitakami Massif, Northeast Japan. The faunas comprise the following genera: Parastacheoceras, Demarezites, Demarezites?, Waagenoceras, Timorites, Tauroceras?, Cardiella, Adrianites, Agathiceras, Agathiceras?, Paraceltites and Cibolites. Parastacheoceras bidentatus gen. and sp. nov. is newly proposed. The genera Demarezites, Tauroceras, Cardiella and Adrianites are described for first time from Japan. Based on these ammonoids, the middle part of the Hosoo Formation, upper part of the Hosoo Formation to the lower middle part of the Kamiyasse Formation, and upper middle part of the Kamiyasse Formation are correlatable with the Middle Permian Roadian, Wordian and Capitanian, respectively. The discovery of genera Demarezites and Cardiella strongly supports the previous hypothesis that the South Kitakami Paleoland was located in the equatorial province during...

Early Permian ammonoids from the Kaeng Krachan Group of the Phatthalung-Hat Yai area, southern peninsular Thailand

An Early Permian small ammonoid fauna consisting of Neocrimites sp., Agathiceras suessi Gemmellaro, A. girtyi Böse, Agathiceras? sp., and Miklukhoceras sp. was found in nodules of a fine sandstone bed exposed in the Phatthalung-Hat Yai area of southern peninsular Thailand. The ammonoid-bearing bed belongs stratigraphically to the uppermost part of the Kaeng Krachan Group, which is essentially a clastic-dominant, Late Carboniferous (?) to Early Permian stratigraphic unit, widely distributed in western and peninsular Thailand. This ammonoid fauna is considered to be of Bolorian (Kungurian) age and includes Agathiceras girtyi Böse, which is described for the first time from Thailand. The present discovery of Bolorian ammonoids suggests that the uppermost part of the Kaeng Krachan Group is slightly younger than previously considered and around the latest Early Permian. This further implies that the continental margin environment of the Sibumasu Block drastically changed at around Bolorian time from a cool, clastic-dominant shelf condition to a temperate to subtropical, carbonate platform due to rapid northward drift after middle Artinskian rifting.

Unconformity between the Upper Maastrichtian and Upper Paleocene in the Hakobuchi Formation, north Hokkaido, Japan: a major time gap within the Yezo forearc basin sediments

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.

The ammonite fauna renewal at the boundary middle–late Toarcian: new data and consequences

Abstract Several proposals have been made concerning the Toarcian informal substages. A three part division, here adopted, includes a Middle Toarcian encompassing the Bifrons and Variabilis ammonite zones, according to the definition well established by Monestier [1921]. Other authors, following Buckman [1888], admit a binary definition but with different meanings. The boundary is placed either below the Variabilis (Lower / Upper Toarcian limit), or below the Thouarsense zones (“Whitbian”–“Yeovilian” limit) [Howarth, 1992]. These differences are largely due to a strong sedimentary instability: condensations, gaps and faunal mixings were widespread during the Variabilis zone in NW Europe and eurocaucasian domain and its Tethyan equivalent, the Gradata zone. Contemporarily, a major renewal occurred in the ammonite faunas. This provoked a near general segregation that is the reason of the use of different zone standards. In NW Europe, the faunal renewal occurred during the Variabilis zone as it as been established in the stratotype localities of Poitou and Vendée (Poitou – Vendée) [Gabilly, 1973, 1976a]. This is also well known in the Causses [Guex, 1972, 1975]. These two areas give good reference sections for the ammonite succession at the top of the Middle Toarcian. These data have been supplemented by recent works concerning NW Europe as well as the Tethyan margins (Portugal, Betics, Morocco, Algeria, Apennines). New observations have also been realized in France (Poitou-Vendée, Causses, Lyon area). They allow to have a better knowledge of the development of the faunal renewal and of the appearance of new taxa (genus, sub and superfamilies). Special attention is given to the Phymatoceratids, Grammoceratids and Hammatoceratoids. In consequence, the main renewal did not happened at the end of the Middle Toarcian (end of the Variabilis zone) but sooner at the beginning of the Illustris subzone. New ammonite morphologies appeared that will dominate the assemblages at the beginning of the late Toarcian (Grammoceratinids) and that will be at the origin of the main Middle Jurassic assemblages (Hammatoceratids). Among the species from the Illustris subzone, some are good markers for the correlations between the faunal domains and provinces (“Pseudogrammoceras” aratum Buck., “Pseudogrammoceras” subregale Pinna, “Geczyceras” costatum (Gab.), Osperleioceras (Pseudopolyplectus) bicarinatum (Ziet.)). It appears that the difficulties to place the Middle–Upper Toarcian limit result closely of the sedimentary perturbations that happened in Europe from the west to the eurocaucasian domains and in the whole western Tethys. The substage problem is secondary as stated by Gabilly but it is convenient for long range comparisons. The main units to establish the correlations are the biostratigraphic zones (biozones). In such a matter, the Variabilis zone is of particular importance, according to the coeval sedimentary and palaeontologic events.

Bajocian ammonites from Msata hill (Lugoba formation) in the hinterland of Dar es Salaam, Tanzania

Ammonites from the Middle Jurassic exposures of the Lugoba Formation at Msata, are described for the first time in Tanzania. Out of a number of ammonite fragments recovered from the bluish-green silty limestone (M3), only three fragments were fairly well preserved to permit their specific identification. Two species were identified: Dorsetensia cf. D. romani (OPPEL) and Oecotraustes (Paroecotraustes?) cf. angustus DOUVILLE . This ammonite assemblage is biostratigraphically correlatable with the Lower Bajocian Posidonia shale of the Kambe Limestone series in Kenya, in which similar ammonites species and other related Bajocian species have been described. Pending new discovery of ammonoid fauna and other guide fossils, on the basis of this ammonite evidence, the Lugoba Formation is reasonably assigned to the Humphrieasianum – Zone of the Lower Bajocian Tanz. J. Sci. Vol.29(2) 2003: 35-42

Origin, phylogeny, faunal composition, and stratigraphical significance of the Albian engonoceratidae (pulchelliaceae, ammonitina) of Peru

Recent study of the Albian ammonite fauna from Peru provides a major revision of the systematic position and taxonomy of the family Engonoceratidae, which we place in the superfamily Pulchelliaceae. We consider the oldest south Tethyan representatives, specifically the mahmoudii species described in Algeria, ancestors of the Andean taxa. Peruvian specimens show a monophyletic evolution marked by four morphological and stratigraphical stages, from unornamented Platiknemiceras to evolute Glottoceras and Engonoceras. The weakly ornamented Parengonoceras haasi, a late lower Albian index species, is considered the ancestor of all Peruvian engonoceratids. The family reaches its highest diversity (15 species) in the upper part of the Lower Albian. The genus Glottoceras, which comprises the majority of the microconchs, is considered an Andean paraphyletic equivalent to the Tethyan genus Knemiceras. Globally, Peruvian engonoceratids are dominated by representatives of the genera Parengonoceras and Glottoceras. We also report several engonoceratids, including Engonoceras and Platiknemiceras, for the first time from Peru.

Tithonian ammonoid biostratigraphy in eastern Himalayan Tibet

The Tithonian and Lower Berriasian sediments in the eastern Himalayas of Tibet contain an extensive sequence of ammonoid fauna. New collections in situ through the Lanongla, Pure, Gucuo and Jiapeila sections have facilitated a major revision of the ammonoid assemblages. Probably due to depositional facies segregation, the Belemnopsis galoi -bearing beds can be regarded as the oldest Tithonian sediments in which the basal Tithonian ammonoid Kossmatia is not present. The Lower Tithonian includes the Virgatosphinctes–Aulacosphinctoides and Uhligites–Aulacosphinctes assemblages; the Upper Tithonian includes the Haplophylloceras pingue , Blanfordiceras wallichi and Haplophylloceras strigile–Corongoceras–Himalayites assemblages. The Spiticeras assemblage is suggested to be from the Lowermost Berriasian. The new ammonoid assemblages at well-defined levels in Himalayan Tibet provide some crucial links for correlation with other regions of the SW Pacific domain where these ammonoid genera have been widely distributed.

Biogeographical and stratigraphical significance of the latest Turonian and Early Coniacian inoceramid/ammonite succession of the Manasoa section on the Onilahy River, south-west Madagascar

Recent, bed-by-bed fossil collections from Manasoa on the Onilahy River, south-west Madagascar, reveal the stratigraphical succession of the inoceramid and ammonite faunas of the topmost Turonian through Lower and possibly lower Middle Coniacian of the area. Six successive interval inoceramid zones are recognised; from bottom upward these are zones of Tethyoceramus modestoides, Tethyoceramus madagascariensis, Tethyoceramus basseae, Tethyoceramus ernsti, Inoceramus? nukeus, and Inoceramus sp. aff. pacificus. The T. modestoides Zone lies within the Turonian. The base of the T. madagascariensis Zone marks the base of the Coniacian; all higher zones also lie within the Coniacian. The succession identified correlates well with other areas of the Southern Hemisphere and, to a lesser degree, with the Euramerican succession. The inoceramid faunas of the topmost Turonian through lower Coniacian of Madagascar are very similar to those of Zululand and are closely related to other Southern Hemisphere faunas. The Madagascan faunas are, however, clearly distinct from Euramerican faunas. The rich ammonite assemblage of the Manasoa section is dominated by endemic species characteristic of the Malgascan province, with only few forms known from Japan, Alaska and Europe. All of the ammonites represent the Barroisiceras onilahyense- Kossmaticeras ( K.) theobaldianum Zone, which is shown to correspond to possibly topmost Turonian and Lower Coniacian. Taxonomic descriptions of the inoceramid species are provided, with range data and photographic documentation.