Foraminiferal paleoecology of the Montpelier and lower coastal groups (eocene-miocene), Jamaica,West Indies

Two domains of carbonate deposition characterized mid-Tertiary Jamaica. After latest Cretaceous to Paleocene orogeny, submergence of insular paleo-Jamaica accompanied the strike-slip or extensional faulting associated with the formation of the Cayman Trench to the north. Differential subsidence along a series of peripheral subsea escarpments (Duanvale-Wagwater escarpment) produced relief in excess of 2000 m by the Late Eocene. Shoalwater limestones covered the slowly subsiding Cornwall-Middlesex platform, thus ending the supply of clastics to deep-sea bottoms north and east of the escarpment where contemporaneous planktonic-foraminiferal pelagites accumulated. Middle Eocene to Middle Miocene carbonate rocks deposited in the deep-sea represent a distinctive lithogenetic unit termed the Montpelier Group.A preponderance of globigerinacean and radiolarian tests characterizes lower Montpelier microfossil assemblages. Dominant benthonic forms include Melonis pompilioides, Fontbotia wuellerstorfi and species of Stilostomella and Pleurostomella. Available faunal criteria including the assemblage composition, depth preferences of extant species and recurrent morphologic-ecologic patterns suggest abyssal (2000 m) paleo-depths at the site of accumulation on a sediment apron near the base of the Duanvale-Wagwater escarpment. Computed from inferred paleodepth and estimated sedimentary thickness, Middle Eocene to Lower Miocene subsidence totals 2800 m. Biostratigraphic and paleoecologic data do not support the prevalent concept of a regional unconformity within the Montpelier.In the Middle Miocene, regional uplift led to the emergence of the Cornwall-Middlesex platform and to pronounced shoaling of marginal sea bottoms. Here, hemipelagic sedimentation resumed during the later Middle Miocene after the carbonate veneer on the adjacent platform was sufficiently eroded so as to expose noncarbonate rocks. See NAPS document No. 02395 for 67 pages of faunal reference lists, maps of sample locations and tables of foraminiferal occurrences. Order from ASIS/NAPS, c/o Microfiche Publications, 305 East 46th St., New York, N.Y., U.S.A. 10017. Remit with order $9.05 for photocopies or $5.55 for microfiche. Make checks payable to Microfiche Publications.     

Biostratigraphy and geodynamic impact in the uppermost part of the northeastern coastal basin of Togo

Lithological and micropaleontological studies of core-samples from five boreholes drilled in the northeastern part of the coastal basin of Togo allow for a specification of the stratigraphy and the paleogeography of this area during the Maastrichtian and Paleogene. A lithological analysis reveals a marine series consisting of a Lower Maastrichtian unit, a Middle Paleocene to Eocene unit, and an upper unit attributed to the Continental terminal sensu lato. The biostratigraphical study, based on planktonic foraminifera, has led to a characterization of the basin in terms of biozones ranging from the Globotruncana aegyptiaca to the Abathomphalus mayaroensis biozones and biozones P5 to P11, thus specifying a Middle to Upper Maastrichtian, an Upper Paleocene and a Lower to Middle Eocene units. The paleogeographical evolution of the area shows that the series recorded two sedimentary cycles: the first one stops at the end of the Cretaceous and the second one in the Paleogene.     

The Phytogeography of the extinct angiosperm Nordenskioeldia (Trochodendraceae) and its response to climate changes

Elucidating the spatio-temporal distributions of terrestrial plants is a key for interpreting the origin of distribution patterns and the tempo of intercontinental disjunction. Nordenskioeldia was distributed in eastern Asia and North America from the Late Cretaceous to the Miocene. Its fossil record provides important information on former patterns of disjunction and dispersal in the Northern Hemisphere. New specimens from the Paleocene of China allow us to further extend the history of the group and provide the impetus to review its distribution in space and time. The comparative morphological survey on fossil Nordenskioeldia found in the Paleocene sediments in both eastern Asia and North America confirms that they belonged to the same morpho-species, which indicates a close floristic continuity between both continents due to land connection available during that time. The spatio-temporal distributions of Nordenskioeldia indicate that the taxon probably expanded eastward from eastern Asia into North America by the end of Early/Middle Maastrichtian, subsequently colonized Greenland, northeastern North America and Spitsbergen in the Early Paleocene, and finally became extinct in the Miocene. The fluctuations in its northern limits took place in response to climate changes: warming from the Paleocene to the Eocene, cooling during the Eocene–Oligocene and amelioration during the Late Oligocene–Mid-Miocene.     

FILLING A GAP: THE FIRST OCCURRENCES OF EPIPHAXUM (CNIDARIA: HELIOPORACEA: LITHOTELESTIDAE) IN THE EOCENE, OLIGOCENE AND MIOCENE

Abstract:  A new species of the genus Epiphaxum (family Lithotelestidae) is described and illustrated in detail, and compared to other species. Epiphaxum arbuscula sp. nov. has been collected from Upper Eocene (Priabonian), Upper Oligocene (Chattian) and Lower Miocene (Upper Burdigalian) deposits of the Aquitaine Basin, south-west France. Epiphaxum is a poorly documented genus but its fossil record extends back to the Late Cretaceous; it was previously known only from the Paleocene (Danian). Epiphaxum arbuscula differs from all others species of the genus in the form of its colony. In contrast to the creeping colonies of previously known species, it has branched colonies. It is very common at one Upper Oligocene outcrop from which an assemblage with submarine cave remains has been described. A close relationship between the three extant species (two from the Caribbean Sea and one from the Indo-West Pacific region) and the Paleogene species is also noted. These constitute a group that has not undergone any important morphological changes for the last 65 million years.     

Geographic and stratigraphic distributions of the Caribbean species of Cladocora (Scleractinia, Faviidae)

A complete account of the faviid genus Cladocora within the Caribbean is presented. In the Caribbean this genus represents an extant group that had its earliest occurrence during the Campanian-Maastrichtian of Jamaica. Recent forms have been reported throughout the Caribbean. The following forms were found (with stratigraphic ranges in the Caribbean): C. arbuscula (Pliocene-Recent), C. debilis (Pleistocene-Recent), C. gracilis (Middle-Upper Maastrichtian), C. jamaicaensis (Campanian-Maastrichtian and Eocene), C. johnsoni (Pliocene), and C. recrescens (Middle-Upper Oligocene). The occurrence of the genus Cladocora in the Caribbean is largely continuous from the Campanian to Recent, during the majority of the Caribbean species show affinities to European assemblages. For the time intervals Paleocene, Lower Oligocene, and Miocene the taxon has not been reported from the Caribbean.     

Paleocene-Pleistocene benthic foraminiferal evidence of major paleoceanographic events in the eastern South Atlantic (DSDP Site 525, Walvis Ridge)

Benthic foraminifers in the size-fraction greater than 0.073 mm were studied in 88 Paleocene to Pleistocene samples from Deep Sea Drilling Project Site 525 (Hole 525A, Walvis Ridge, eastern south Atlantic). Clustering of the samples on the basis of the 86 most abundant foraminifers (in total, 331 taxa were identified) allowed separating two major assemblage zones: the Paleocene to Eocene interval, and the Oligocene to Pleistocene interval. Each of these, in turn, were subdivided into three minor subzones as follows: lower upper Paleocene (approx. 62.4 to 57.8 Ma); upper upper Paleocene (56.6 to 56.2 Ma); lower and middle Eocene (55.3 to 46.8 Ma); upper Oligocene to middle Miocene (25.3 to 16 Ma); middle Miocene to Pliocene (15.7 to 4.2 Ma); and lower Pleistocene (0.4 to 0.02 Ma), with only minor differences with the previous zone. Some very abundant taxa span most of the column studies (Bolivina huneri, Cassidulina subglobosa, Eponides bradyi, E. weddellensis, Gavelinella micra, Oridorsalis umbonatus, etc.). Several of the faunal breaks recorded coincide with conspicuous minima in the specific diversity curve, thus suggesting that the corresponding turnovers signal the final stages of periods of faunal impoverishment. At least one major bottom-water temperature drop (as derived from δ¹⁸O data) is synchronous with a decrease in the foraminiferal specific diversity. On the other hand, a specific diversity maximum in the middle Miocene might be associated with a δ¹³C increase at approx. 16 to 12 Ma. Highest foraminiferal abundances (up to 600–800 individuals per gram of dry sediment) occurred in the late Paleocene and in the early Pleistocene, in coincidence with the lowest diversity figures calculated. The magnitude of the most important faunal turnover recorded, between the middle Eocene and the late Oligocene, is magnified in our data set by the large hiatus which separates the middle Eocene from the upper Oligocene sediments. Considerably smaller overturns occurred within the late Paleocene (in coincidence with changes in the specific diversity, absolute abundance of foraminiferal tests, and δ¹³C), and in the middle Miocene (in coincidence with a specific diversity maximum and a δ¹³C excursion). New information on the morphology and the stratigraphic ranges of several species is furnished. For all the taxa recorded the number of occurrences, total number of individuals identified and first and last appearances are listed.     

New observations on the Late Miocene–Early Pliocene Lutrinae (Mustelidae: Carnivora,Mammalia) from the Middle Awash,Afar Rift,Ethiopia

New observations on the Late Miocene and Earliest Pliocene mustelids from the Middle Awash of Ethiopia are presented. The Middle Awash study area samples the last six million years of African vertebrate evolutionary history. Its Latest Miocene (Asa Koma Member of the Adu-Asa Formation, 5.54–5.77 Ma) and Earliest Pliocene (Kuseralee and Gawto Members of the Sagantole Formation, 5.2 and 4.85 Ma, respectively) deposits sample a number of large and small carnivore taxa among which mustelids are numerically abundant. Among the known Late Miocene and Early Pliocene mustelid genera, the Middle Awash Late Miocene documents the earliest Mellivora in eastern Africa and its likely first appearance in Africa, a new species of Plesiogulo, and a species of Vishnuonyx. The latter possibly represents the last appearance of this genus in Africa. Torolutra ougandensis is known from both the Late Miocene and Early Pliocene deposits of the Middle Awash. The genus Sivaonyx is represented by at least two species: S. ekecaman and S. aff. S. soriae. Most of the lutrine genera documented in the Middle Awash Late Miocene/Early Pliocene are also documented in contemporaneous sites of eastern Africa. The new observations presented here show that mustelids were more diverse in the Middle Awash Late Miocene and Early Pliocene than previously documented.     

Biostratigraphy and stage boundaries of the upper Cretaceous–early Paleogene successions in southern Galala area,North-Eastern Desert,Egypt

The foraminiferal contents of three surface sections [Gebel Tarboul, Wadi Tarfa (WT) and Bir Dakhl (BD) sections] in southern Galala area, North-Eastern Desert, Egypt, have been studied in detail and used in biostratigraphy and chronostratigraphy of the upper Cretaceous–Paleogene successions. Sixty-nine planktonic foraminiferal species belonging to 23 genera have yielded 17 biozones. They are given in ascending order: Globotruncana aegyptiaca Interval Zone (IZ), Gansserina gansseri IZ, Contusotruncana contusa–Racemiguembelina fructicosa IZ, Abathomphalus mayaroensis IZ, P1c, P2, P3, P3a, P3b, P4, P4a, P4b, P4c, P5, E1, E2, E3, E4 and E5. Moreover, local and widespread regional hiatus was detected in the pelagic to hemipelagic sequence during Cretaceous–Paleogene boundary in southern Galala Sub-basin. This hiatus corresponds to the Early Maastrichtian–Early Eocene in Gebel Tarboul, the interval between Late Maastrichtian–Early Paleocene throughout WT sequences and Late Maastrichtian–Late Paleocene in BD section.     

Herpetofaunas from the Upper Paleocene and Lower Eocene of Morocco

Two Upper Paleocene and one Lower Eocene localities from Morocco (Ouarzazate basin) have yielded terrestrial assemblages that stand among the rare herpetofaunas from the Paleogene of the African Plate. The collections include one of the rare frogs and the only lizards known from the Paleogene of Africa. One of the two Upper Paleocene localities, Adrar Mgorn 1, has produced an indeterminate anuran and the most diverse assemblage of squamates from the Mesozoic and Cenozoic of Africa. It has yielded the earliest known scolecophidian snake and the earliest Gekkonidae, amphisbaenians, Tropidophiidae, and perhaps Boidae from Africa. Moreover, a specimen represents either the last sphenodontian or the earliest acrodontan lizard from this continent. One of the amphisbaenians represents a very distinct new taxon, Todrasaurus gheerbranti gen. and sp. nov. Indeterminate scincomorphans, lacertilians, Madtsoidae, and Aniliidae are also present. The fauna from the Lower Eocene is less diverse than that from the Upper Paleocene, but some taxa are common to both levels. Contrary to nearly all other Paleogene herpetofaunas from the African Plate, these Paleocene and Eocene assemblages include taxa that were terrestrial, not aquatic.     

Ostracodes et stratigraphie du néogène et du quaternaire méditerranéens

A stratigraphical chart of marine ostracoda from Lower Miocene to Recent is established. Selected species (approximatively 220) are those morphologicaly well characterized and known from different parts of the Mediterranean area. It appears that: • lower Miocene ostracodes are still poorly known; • specific diversity is high during the Tortonian and the Lower Messinian before the complete disappearance of marine Mediterranean species during the Upper Messinian évaporitic episodes; • during the early Pliocene, about half of the Upper Miocene marine species are reintroduced with the Atlantic waters; other species migrate for the first time in the Mediterranean Sea by the same way; • at the end of the Pliocene or at the beginning of the Pleistocene several species known in Mediterranean since the Middle Miocene or before, such as Cytherella sp. gr. transversa and Ruggieria tetraptera, as well some “nordic guests” such as Hemicythere villosa and Cythere lutea, appear. This work is an opportunity to confirme a Late Miocene age for the Neogene of Skyros (Aegean Sea), to assign the “Upper Pliocene” of Terquem to the Lower Pleistocene and to refute the existence of a pliocene psychrosphere.