Subfossil tooth of a dwarf Hippopotamus (Mammalia, Artiodactyla) from the Holocene of the Berivotra ouctrops (Mahajanga Basin, NW Madagascar), with remarks on the distribution of the genus in the island (original) (raw)
Related papers
Marine Micropaleontology, 2003
Lithology, geochemistry, stable isotopes and integrated high-resolution biostratigraphy of the Berivotra and Amboanio sections provide new insights into the age, faunal turnovers, climate, sea level and environmental changes of the Maastrichtian to early Paleocene of the Mahajanga Basin of Madagascar. In the Berivotra type area, the dinosaur-rich fluvial lowland sediments of the Anembalemba Member prevailed into the earliest Maastrichtian. These are overlain by marginal marine and near-shore clastics that deepen upwards to hemipelagic middle neritic marls by 69.6 Ma, accompanied by arid to seasonally cool temperate climates through the early and late Maastrichtian. An unconformity between the Berivotra Formation and Betsiboka limestone marks the K^T boundary, and juxtaposes early Danian (zone Plc? or Pld) and latest Maastrichtian (zones CF2^CF1, Micula prinsii) sediments. Seasonally humid warm climates began near the end of the Maastrichtian and prevailed into the early Danian, accompanied by increased volcanic activity. During the late Danian (zones P1d^P2), a change to seasonally arid climates was accompanied by deepening from middle to outer neritic depths. ß
The Journal of Geology, 2001
Upper Cretaceous strata of the Mahajanga Basin, northwestern Madagascar, yield some of the most significant and exquisitely preserved vertebrate fossils known from Gondwana. The sedimentology of these strata and their stratigraphic relations have been the focus of renewed geological investigations during the course of five expeditions since 1993. We here designate stratotypes and formalize the terrestrial Maevarano Formation, with three new members (Masorobe, Anembalemba, Miadana), and the overlying marine Berivotra Formation. The Maevarano Formation accumulated on a broad, semiarid alluvial plain bounded to the southeast by crystalline highlands and to the northwest by the Mozambique Channel. The Berivotra Formation was deposited in an open marine setting that evolved from a clastic-to a carbonate-dominated shelf, resulting in deposition of the overlying Betsiboka limestone of Danian age. New stratigraphic data clearly indicate that the Maevarano Formation correlates, at least in part, with the Maastrichtian Berivotra Formation, and this in turn indicates that the most fossiliferous portions of the Maevarano Formation are Maastrichtian in age, rather than Campanian as previously reported. This revised age for the Maevarano vertebrate assemblage indicates that it is approximately contemporaneous with the vertebrate fauna recovered from the Deccan basalt volcano-sedimentary sequence of India. The comparable age of these two faunas is significant because the faunas appear to be more similar to one another than either is to those from any other major Gondwanan landmass. The revised age of the Maevarano Formation, when considered in the light of our recent fossil discoveries, further indicates that the ancestral stocks of Madagascar's overwhelmingly endemic modern vertebrate fauna arrived on the island in post-Mesozoic times. The basal stocks of the modern vertebrate fauna are conspicuously absent in the Maevarano Formation. Finally, the revised age of the Maevarano Formation serves to expand our global perspective on the K/T event by clarifying the age of a diverse, and arguably the best preserved, sample of Gondwanan vertebrates from the terminal Cretaceous.
Cretaceous Research, 2013
A new member of the Upper Cretaceous (Maastrichtian) Maevarano Formation is proposed to accommodate a distinctive succession of strata exposed along the shores of Lac Kinkony in northwestern Madagascar. The new Lac Kinkony Member overlies fully terrestrial sandstones of the Anembalemba Member of the Maevarano Formation, and is capped by marine dolostones of the Berivotra Formation. In the stratotype section, the base of the Lac Kinkony Member consists of siltstone interbeds that host networks of Ophiomorpha. Siltstone facies pass up-section to distinctive white sandstones packed with dolomitic mud matrix that exhibit rhythmic clay drapes, flaser and wavy bedding, and oppositelyoriented ripples developed on the toes of larger foresets. Thin flat interbeds of microgranular dolostone and claystone comprise the uppermost facies of the Lac Kinkony Member, and a laterally traceable ravinement bed mantled by cobbles of rounded dolostone marks the contact with the superjacent Berivotra Formation. Deposits of the Lac Kinkony Member are interpreted to represent siliciclastic and carbonate tidal flats dissected by tidally-influenced rivers. Vertebrate fossils are abundantly preserved in these coastal deposits, and are locally concentrated in microfossil bonebeds that have the potential to yield thousands of small identifiable specimens. In addition to many taxa already known from the Maevarano Formation, the Lac Kinkony Member has yielded a wealth of phyllodontid albuloid fish skull elements, the distal humerus of a new frog taxon, five vertebrae representing two new snakes, a tooth of a possible dromaeosaurid, and a complete skull of a new mammal. The discovery of several new vertebrate taxa from this new member reflects the fact that it samples a previously unsampled nearshore, peritidal paleoenvironment in the Late Cretaceous of Madagascar.
Journal of African Earth Sciences, 2004
As part of an intradisciplinary project which was concerned with the early rifting processes between Madagascar and East Africa, the Middle to Upper Jurassic sedimentary sequences of the Morondava Basin in Southwest Madagascar has been investigated with respect to biostratigraphy, sedimentary facies and palaeoecology. The transgressive sedimentary sections in the Bajocian and Callovian-Oxfordian yield rich macro-and microfossil assemblages which improved the biostratigraphic framework and gave some important information about the palaeoenvironments. Palaeogeographic distribution patterns of the Bajocian ostracod Paradoxorhyncha are suggestive of a migration along the southern shores of Gondwana between Madagascar, Australia and South America. The Callovian ostracods show strong affinities to the Indian faunas, indicating existence of a free migration route for shallow marine benthic organisms between Madagascar and India. Significant faunal differences between Madagascar and Tanzania suggest a physical or environmental migration barrier between Madagascar and East Africa during the Callovian to Kimmeridgian interval. The Upper Jurassic ostracods from the northern and eastern margin of Gondwana show a very high degree of endemism and they can be assigned to two faunal provinces in North Gondwana (Arabia, Near East,
Argesis - Studii și comunicări. Științele naturii., 2019
The microvertebrate fossil sites of the Hațeg Basin are essential in understanding the composition of the continental Maastrichtian fauna of western Romania, and its temporal evolution. This paper describes additional fossil vertebrate remains discovered at the "Pui Swamp locality", one of the geologically oldest Maastrichtian localities in the Hațeg Basin. Albanerpetontid and anuran amphibian, crocodyliform, lizard, and kogaionid mammal remains, as well as small fossil eggshell fragments are described, representing novel occurrences that improve the knowledge on the composition of the oldest Maastrichtian vertebrate assemblages of the area.
Faunal similarity in Madagascan and South Indian Late Cretaceous vertebrate faunas
Palaeogeography, Palaeoclimatology, Palaeoecology, 2017
Substantial new information is presented on upper Artinskian-Kungurian deposits in Timor-Leste and in the Canning, Southern Carnarvon and northern Perth basins of Western Australia. These basins, situated between about 35°S and 55°S palaeolatitude, formed part of the East Gondwana interior rift, a precursor to the rift that 100 my later formed the Indian Ocean in this region. Timor lay near the main axis of the East Gondwana interior rift, whereas the Western Australian basins were marginal splays from the rift axis. The main depocentres developed as a result of faulting that was initiated during the Late Pennsylvanian. Detailed lithostratigraphic and biostratigraphic analyses have been made on the newly recognized Bua-bai limestone and the type Cribas Group in Timor, the Noonkanbah Formation in the Canning Basin, the Byro Group in the Merlinleigh Sub-basin of the Southern Carnarvon Basin, and the Carynginia Formation in the northern Perth Basin. In Timor the succession, which is highly disrupted by faulting, was deposited under open-marine conditions probably in a shelf-basin setting. Restricted, very shallow-water seas flooded the Canning Basin and the Merlinleigh-Byro-Irwin sub-basins of the Southern Carnarvon and northern Perth basins and had highly variable oxygen levels and salinities typical of estuarine environments. A similar pattern of warming and bathymetric change is recognized in all studied basins. During the early part of the late Artinskian cool conditions prevailed, with water temperatures 0-4°C forming sea ice in the Merlinleigh-Byro-Irwin rift. Rapid warming during the latter part of the late Artinskian was accompanied by maximum marine flooding close to the Artinskian-Kungurian boundary. Climatic and bathymetric conditions then allowed carbonate mounds, with larger fusulines and a variety of algae, to develop in the northern part of the rift system, and
Late Cretaceous crocodile remains from Naskal (India): comparisons and biogeographic affinities
Annales De Paleontologie, 2002
Crocodile teeth from the Maastrichtian inter-trappean beds of Naskal (peninsular India) are described here. Because of isolated denticles visible on sufficiently preserved carinae, the presence of a strong heterodonty (in size and shape), and by comparison to crocodile teeth from various taxa, they are considered as representing a ziphodont form with a heterodont dentition. The difference between ziphodont, "false ziphodont" and non-ziphodont dentitions is evaluated. With the help of scanning electron microscope photographs, it is shown that only precise characteristics of the denticles and not the tooth shape, allow to distinguish the three categories. These three categories do not correspond to monophyletic groups. It is also shown that the "alligatorid" heterodonty, meso-or eusuchian in grade, exists in each category. Although the ziphodont dentition is not sufficient to allow a taxonomical definition, the peculiarities that it often presents, depending on the taxa as well as the teeth shape, enable systematic approaches. An examination of previous works on the possible ziphodont crocodiles from the Tertiary deposits of the Indian subcontinent and on Naskal teeth demonstrate that the latter are closer to those of some Gondwanan crocodiles of mesosuchian grade, known from the early Cretaceous of Africa and possibly a form from the late Cretaceous of Madagascar. They are excluded from eusuchian Laurasiatic as well as Paleogene forms of the Indian subcontinent, either ziphodont or not. Contrary to the earlier works on the inter-trappean crocodiles, the present study removes this group as one of the evidences in support of an early (late Cretaceous-early Tertiary) India/Asia collision model. In fact, it provides an additional support for the existence of possible Cretaceous biogeographic links between India, Madagascar, Africa, and South America.
Miocene Shark and Batoid Fauna from Nosy Makamby (Mahajanga Basin, Northwestern Madagascar)
PLOS ONE, 2015
Madagascar is well known for producing exceptional fossils. However, the record for selachians remains relatively poorly known. Paleontological reconnaissance on the island of Nosy Makamby, off northwest Madagascar, has produced a previously undescribed assemblage of Miocene fossils. Based on isolated teeth, ten taxonomic groups are identified: Otodus, Carcharhinus, Galeocerdo, Rhizoprionodon, Sphyrna, Hemipristis, Squatina, Rostroraja, Himantura and Myliobatidae. Six are newly described from Madagascar for the Cenozoic (Galeocerdo, Rhizoprionodon, Sphyrna, Squatina, Rostroraja and Himantura). In association with these specimens, remains of both invertebrates (e.g., corals, gastropods, bivalves) and vertebrates (e.g., bony fish, turtles, crocodylians, and sirenian mammals) were also recovered. The sedimentary facies are highly suggestive of a near-shore/coastal plain depositional environment. This faunal association shares similarities to contemporaneous sites reported from North America and Europe and gives a glimpse into the paleoenvironment of Madagascar's Miocene, suggesting that this region was warm, tropical shallow-water marine.
2010
Due to the near lack of a Cenozoic fossil record, little is known about the origin and evolution of Madagascar's extant fauna. Madagascar's subfossil record (Late Pleistocene and Holocene) has been important for filling in the most recent part of this informational gap, contributing details on diversity and distribution changes in the recent past, but most research has focused on larger animals. Less attention has been given to the subfossil record of small mammals, despite the fact that these groups represent a substantial portion of the extant mammalian diversity. To evaluate the potential presence of subfossil microfaunal remains in cave breccias (calcite sediment), we used acetic acid to dissolve the matrix surrounding a nearly complete skull and mandible of Archaeolemur sp. cf. A. edwardsi from Anjohibe Cave, northwestern Madagascar. The resulting residue included fossil remains of all five orders represented by Madagascar's extant mammals (Afrosoricida, Carnivora, Chiroptera, Rodentia, and Primates), and one order, Artiodactyla, currently extinct in Madagascar, except for introduced forms. Species identified include Microgale sp. (Afrosoricida: Tenrecidae), Eliurus myoxinus (Rodentia: Nesomyidae), Hipposideros sp. cf. H. besaoka and Triaenops sp. (Chiroptera: Hipposideridae), Galidia elegans (Carnivora: Eupleridae), Cheirogaleus medius and Microcebus murinus (Primates: Cheirogaleidae), and Hippopotamus lemerlei (Artiodactyla: Hippopotamidae). Radiocarbon dating shows that non-associated surface finds of small mammals tend to be younger than extinct larger mammals at Anjohibe, underscoring the importance of using other methods to establish temporal associations of small and large mammals. This research demonstrates the potential for recovering subfossils from matrix that are typically discarded during the preparation of larger fossils, and highlights the potentially significant loss of information if such sediments are ignored.