Annales de Paleontologie最新文献

The origin of the turtle fauna of Malesia is analysed here through a review of the literature, a re-evaluation of previously described material, and the description of new material. Very few data are available prior to the Quaternary. While the Early Pleistocene record is largely dominated by reports of giant tortoises, the Middle Pleistocene record provides reports of the first occurrences of most extant taxa living in the area. Most, if not all, of the faunas have stronger relationships with Indochinese than with East Asian taxa, suggesting that colonisation largely followed the Siva- or Sino-Malayan routes, allowing turtles to invade the Sunda Shelf and disperse further east during periods of low sea-level. On the other hand, there is nearly no fossil data to understand the origin of the six endemic Malesian species, but molecular studies suggest that most of these taxa may have evolved in Malesia well before the Quaternary dispersal of the Indochinese fauna. In addition to clarify several fossil identifications, we provide evidence that the box turtle of the ``Cuora amboinensis'' species complex arrived in the Philippines before the early Middle Pleistocene. We also confirm that Duboisemys isoclina is an endemic extinct genus and we discuss its relationship to continental and endemic turtles.

New crocodyliform fossils have been discovered from the Lower Cretaceous Kitadani Formation of the Tetori Group, Fukui, Japan. They include skull elements (premaxilla, maxilla, parietal, quadrate and dentary), postcranium elements (dorsal vertebra, caudal vertebra, femur and osteoderm) and isolated teeth, and are described as goniopholidid crocodyliforms. Phylogenetic analysis resulted in nesting the Kitadani goniopholidid at the basal position of Goniopholididae and one autapomorphy is recognized: presence of the parietal sagittal crest. In addition, the narrow snout and a heterodont dentition in jaws of this goniopholidid is a unique combination of rostral morphology among Goniopholididae. Generally, the basal taxa bear a narrow snout with homodont dentition, and the heterodont dentition is seen in derived broad-snouted taxa. Judging from those rostral shape and dentitions, the Kitadani form possessing acute caniniform and blunt teeth tends to be more opportunistic as foraging strategy than other basal narrow-snouted goniopholidids with only acute caniniforms throughout. Our new discovery is the first osteological report of Japanese Cretaceous crocodyliform. Siamosuchus phuphokensis from the Early Cretaceous Sao Khua Formation, Khorat Group also shows combination of basal and derived cranial characters. Transitional species from Asia suggest allopatric speciation of goniopholidid in geographically intermediate Asian area.

Although the first identification of an Asian spinosaurid theropod, Siamosaurus suteethorni from the Sao Khua Formation of Thailand, was published in 1986, what was in all likelihood a spinosaurid tooth was collected from the type section of the Sao Khua Formatio in the course of a stratigraphic survey of the Khorat Plateau (north-eastern Thailand) as early as 1962. The specimen, the present whereabouts of which are unknown, was described in 1963 as an ichthyosaur tooth, but apparently was the first dinosaur specimen to be reported from Thailand. On the basis of the description and figures, it is referred to the spinosaurid genus Siamosaurus. A purported plesiosaur tooth from the Phu Kradung Formation, described in the same paper, apparently belonged to a crocodile. The reasons for the initial misidentification of the spinosaurid tooth are reminiscent of those of other misinterpretations of similar teeth found in other parts of the world.

While temnospondyl fossils have been relatively well documented in the Western world and Africa; research on temnospondyl fossils in South-East Asia and India has received less attention. Nonetheless, they add a substantial amount to the record of palaeobiogeographic distribution of the Triassic temnospondyl amphibians. During the Triassic, almost every temnospondyl family (aside from dissorophoids) was present in India. According to the findings, the assemblage and species diversity of Triassic temnospondyl amphibians peaked in the Early Triassic. With climatic stability and ecological saturation in the Middle and Late Triassic, diversification slowed down or gradually decreased. The Jaccard Similarity coefficient of the Triassic temnospondyl contents in South-East Asia and India shows an agreement in palaeobiogeography; the coefficients reflect the geography of Pangea. According to the Euler diagram, the junction of the Triassic temnospondyls in South-East Asia and India indicates that these regions of India did not have endemic Triassic temnospondyl populations.

Within the order Carnivora, mustelids represent the most diverse family worldwide, with a great ecomorphological diversity in terms of diet, size and locomotory adaptations. Among them, the subfamily Lutrinae corresponds to semiaquatic forms, in which the genus Lontra is included. Widely distributed at present day, this genus is represented by three species across South America (Lontra longicaudis, Lontra felina and Lontra provocax), however their fossil record in the continent is very scarce. In the present contribution, new fossil material assigned to the Neotropical otter Lontra cf. L. longicaudis are described from late Pleistocene – early Holocene (Lujanian Stage/Age) deposits of Uruguay (Sopas and Dolores formations). Based on these findings, some aspects related to the knowledge of the group, paleoecology and paleoenvironmental conditions are discussed.

In this study, the biostratigraphy of the reservoir sediments of the upper part of the Dalan Formation (Late Permian, Lopingian) and the reservoir part of the Kangan Formation (Early Triassic) from one of the well in the northern part of South Pars field are studied. The results of studies are presented as three local biozones recognized and defined. Based on these studies, a Late Permian age (Dorashamian/Changhsingian) for the upper Dalan Member an Early?—Middle Triassic age (Scythian?—Anisian) for the lower part of the Kangan Formation, suggested. Also, based on microfossils stratigraphical distribution, and studying succession and continuity of locally defined biozones, it was distinguished a hiatus between Dalan and Kangan formations. Therefore it could be mentioned that the Dorashmian age is the youngest part of the Dalan Formation.

Biogenic signatures in Precambrian rocks are often difficult to confirm and debatable. We present some unusual features associated with microbial-mat related structures (MRS) from the freshly-exposed rippled bed surface of 1.6 Ga old Chorhat Sandstone, Vindhyan Supergroup, India. The features discussed here, are present within intertidal to supratidal environments often affected by storms. One of the features includes ridge-groove couplets that run across the ripple crests. Locally, the ridge-groove couplet forms a braid-like pattern. Along the ripple troughs, the ridges are considerably long and maintain a uniform width on the mm scale. Another feature shows meandering grooves bordered by ridges. The grooves swerve, form loops, cut across older grooves, and branch up. None of them have comparable equivalents in the Precambrian record described thus far. The invariably uniform width of the ridges for both the two features cannot be compared with undersurface gas bubble migration, and the swerving and reversing nature of the grooves denies passive movement of any inorganic/organic masses under the influence of an external force. They seem to have been created by movement through a microbiota-rich surficial sediment. Such unusual features raise questions about the biosphere and biotic structures during the Boring Billion (1.8–0.8 Ga).

During the Palaeocene-Eocene transition, the southern Tethys margin is characterized by several African phosphate deposits with many fossil teeth of elasmobranchs. Contrary to the rich Moroccan fossil record, fossil elasmobranchs from the area that includes today the Algerian-Tunisian border (e.g. Metlaoui-Gafsa-Onk Basin) have received few attentation since the last century of exploration. New collecting in the vicinity of Tebessa, Eastern Algeria (Jebel El Onk mine) allowed to report a new elasmobranch fauna in the so-called “Upper Thanetian” level. It consists of 28 taxa including a new species of a galeocerdid, Physogaleus onkensis sp. nov., which is characterized by a possible crushing adaptability of their teeth. The majority of the reported species are known in coeval phosphate levels enabling preliminary conclusions about the depositional time and correlations to the related faunas of the region. The faunal from the Jebel El Onk mine is considered as late Thanetian–early Ypresian in age.