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31.
Shallow water rudist bivalves are a very suitable tool for palaeoenvironmental and palaeobiogeographic reconstructions of the Cretaceous Tethys. For this reason, we have reviewed fossil localities bearing polyconitid rudists of the late Aptian and Albian in the Himalayan area and in other Tethyan sites. The well preserved Rossi Ronchetti rudist collection of Yasin (Kohistan Himalayas) has been reinspected as a reference for the regionally distinctive Horiopleura haydeni biofacies. Two morphotypes of the genus related to different sedimentary settings were distinguished on the basis of biometric measurements. Assemblages characterized by benthic organisms of Mesogean affinity dominated by polyconitid and radiolitid rudists, together with nerineid gastropods, corals and orbitolinid forams have a distinct provincial significance. Today, various polyconitid bearing biofacies can be recognized in many sedimentary successions of the Himalayas, westwards to the Iberia region and even eastwards to the Pacific area. Their distribution allows recognition of a palaeobiogeographic pattern influenced by a thermal barrier. It also helps to understand how the accretion of the Lhasa terrane and the Kohistan-Dras intra-oceanic volcanic arc could represent a spreading centre for the “Yasin-type” Horiopleura haydeni biofacies (marked by the absence of Polyconites) in the South West Asian Province. 相似文献
32.
Pinaki Roy Subhendu Bardhan Aparajita Mitra Sudipta K. Jana 《Journal of Asian Earth Sciences》2007,30(5-6):629-651
The Bathonian ammonite assemblages have been previously poorly recorded in Kutch. The present study has unearthed a rich array of ammonite taxa ranging from the Middle to Upper Bathonian. While Oxycerites Rollier (1909) is a new record from Kutch, the oldest occurrence of Choffatia Siemiradzki (1898) has been found from the Middle Bathonian horizon. Oxycerites cf. orbis (Giebel) is a zonal index of the Late Bathonian in other areas and thus facilitates interprovincial correlation. Besides, palaeobiogeographic and stratigraphic distribution of many species have been modified based on new information. For example, macrocephalitin species, i.e., Kamptokephalites cf. etheridgei Spath (1928), Macrocephalites bifurcatus transient intermedius Spath (1928), M. cf. mantataranus Boehm (1912) were previously known from West Pacific, Indonesia have been now found in Kutch. Gracilisphinctes Buckman (1920) has been previously known to occur during the Middle Bathonian time, the present work extends its stratigraphic distribution up to the definite Upper Bathonian horizon. Procerites hians (Waagen) an endemic species in Kutch previously known from the Upper Bathonian beds, its stratigraphic range has been extended down to the Middle Bathonian.Detail taxonomy of the newly obtained taxa has been done and in many cases sexual dimorphism has been recognized. 相似文献
33.
Ornithuromorph birds (the clade which includes modern avian radiation) first appeared in the Early Cretaceous in Asia and achieved a great diversity during the latest ages of the Late Cretaceous (Campanian and Maastrichtian). The evolutionary history of orithuromorphs during the first 17 MYAs of the Late Cretaceous (Cenomanian to Santonian ages) remains very poorly known, as the fossil record for this time interval is largely restricted to several isolated finds of the classic avian genus Ichthyornis in North America. Here we describe an isolated distal tibiotarsus of an evolutionary advanced bird, morphologically similar to Ichthyornis, from the middle Cenomanian of Saratov Province, European Russia. This is the first documentation of an Ichthyornis-like bird in the Old World. The find further constitutes only the second pre-Campanian record of the Late Cretaceous Ornithuromorpha in Eurasia, the second record of Cenomanian birds in Russia. This discovery shows that Ichthyornis-like birds enjoyed a wide geographical distribution as early as the beginning of the Late Cretaceous. Given that the earliest and the most primitive ornithuromorph birds are known from Asia, the new find supports a Eurasian origin for Ichthyornithidae. 相似文献
34.
Oligocene and Early Miocene coral assemblages from three sections of central Iran are investigated with respect to their
palaeoecological and palaeobiogeographic implications. These corals are compared with faunas from the Mediterranean Tethys
and the Indopacific. Associated larger foraminifers are used for biostratigraphy and to support the palaeoecological interpretation.
The studied sections are situated in the foreland basins of the Iranian Plate which is structured into a fore-arc and a back-arc
basin separated by a volcanic arc. The coral assemblages from Abadeh indicate a shallowing-upward trend. Infrequently distributed
solitary corals at the base of the section indicate a turbid environment. Above, a distinct horizon characterised by a Leptoseris-Stylophora assemblage associated with lepidocyclinids and planktonic foraminifers is interpreted as maximum flooding surface. Small
patch reefs with a Porites-Faviidae assemblage are a common feature of Late Oligocene to Early Miocene coral occurrences and indicate water depths of
less than 20 m. The diversity of the coral faunas shows marked differences. Oligocene corals from the Esfahan-Sirjan fore-arc
basin comprise more than 45 species of 32 genera and occur in a wide range of environments. Early Miocene corals from the
Qom back-arc basin are less frequent, show a lower diversity (13 genera with 15 species) and occur in single horizons or small
patch reefs.
Received: 4 December 1998 / Accepted: 3 June 1999 相似文献
35.
Pipid frogs are fully aquatic frogs that today inhabit freshwater environments of southern continents on both sides of the Atlantic Ocean, with a fairly good fossil record dating back to the Cretaceous. Here I report on fossils from the Allen Formation (upper Campanian–lower Maastrichtian), Río Negro Province, Argentina, that are ascribed to a new genus and species of pipid. In order to assess the evolutionary relationships of the new taxon, which is represented by sphenethmoids, otic capsules, ilia, humeri, and vertebrae, cladistic analyses of a data matrix of 165 osteological characters scored for 36 taxa were performed. The results are congruent with previous hypotheses of pipoid interrelationships and consistently place the new taxon as part of the lineage today represented by the African xenopodines. Temporal calibration of the phylogenetic tree based on the fossil record imply that the origin and early diversification of crown-group Pipidae might have occurred during the Early Cretaceous, prior to the final breakup of western Gondwana. This study highlights the importance of including fossils, even fragmentary ones, directly in phylogenetic analyses in order to disentangling how, when, and where pipid frogs diversified. 相似文献
36.
The shallow-marine, mixed siliciclastic-calcareous Late Cretaceous deposits from the Apuseni Mountains have been extensively studied and compared to coeval deposits from the Alpine Gosau. The former are mainly represented by conglomerates, sandstones, marls, and limestones with rudists that unconformably overlie the crystalline basement and its Permo-Mesozoic cover. Our new, detailed investigations on the rudist fauna from Măgura Hill, the type locality of Pseudopolyconites hirsutus (Patrulius) and Miseia costulata Patrulius, indicate a Late Santonian–Early Campanian age for these deposits instead of an Early Santonian one as previously suggested (Patrulius, 1974). This study also mentions for the first time the occurrences of Pseudosabinia klinghardti (Böhm) and Pseudopolyconites parvus Milovanović in the rudist-bearing deposits from the Apuseni Mountains. We include their palaeontological features, as well as the ones for Pseudopolyconites hirsutus. Based on new biostratigraphic data, our study expand the stratigraphic range of Pseudosabinia klinghardti and Pseudopolyconites parvus – previously considered characteristic for the Early Campanian–Maastrichtian interval. Also we add new information on their palaeobiogeographic distribution within the central-eastern Mediterranean area during the Late Cretaceous. 相似文献
37.