The Azhdarchidae have come to be known as the most diverse clade of Late Cretaceous pterosaurs and largest flying creatures in existence. Since erection taxon nearly four decades ago, many partial specimens been referred it from Early Jurassic, but none these identifications can confirmed. comprehensive phylogenetic analysis taxonomy Pterosauria is presented, evolutionary history reviewed. As c...

Late Maastrichtian to Danian dinoflagellate cyst and calcareous nannofossil biostratigraphy was analyzed at the Sur Río Chico borehole, Austral Basin, Argentina. Two stratigraphical intervals from 965 1003 m below ground surface of drilled section were defined. The co-occurrence Manumiella bertodano, M. seelandica conorata in 990–1000 1000–1003 mbgs interval, associated with top Neprolithus fre...

BACKGROUND Rhabdodontid ornithopod dinosaurs are characteristic elements of Late Cretaceous European vertebrate faunas and were previously collected from lower Campanian to Maastrichtian continental deposits. Phylogenetic analyses have placed rhabdodontids among basal ornithopods as the sister taxon to the clade consisting of Tenontosaurus, Dryosaurus, Camptosaurus, and Iguanodon. Recent studie...

for biostratigraphic studies, based on calcareous nannofossils, a thickness of 480 meters of cretaceous deposits in shushud section (north birjand) has been measured and sampled. the studied section is composed of shale, marl, marine sandstone and sandy limestone. the shale and marl units were more suitable for sampling. according to taxonomical studies, 10 genera and 25 species in shushud sect...

Three teeth of the shark Serratolamna serrata (Agassiz) from the Guinea Corn Formation (Central Inlier) represent the first recorded occurrence of fossil sharks from Cretaceous rocks of Jamaica. This occurrence increases the known palaeogeographical distribution of S. serrata, which appears to have been global. This species is largely known from the Upper Maastrichtian, which helps confirm the ...

Many palaeobiological analyses have concluded that modern birds (Neornithes) radiated no earlier than the Maastrichtian, whereas molecular clock studies have argued for a much earlier origination. Here, we assess the quality of the fossil record of Mesozoic avian species, using a recently proposed character completeness metric which calculates the percentage of phylogenetic characters that can ...

The Arkadelphia Formation—Midway Group (Maastrichtian—Paleocene) contact near Malvern, Arkansas preserves a K-Pg boundary assemblage of turtle species consisting of skull, shell, and non-shell postcranial skeletal elements. The Malvern turtles are preserved within a coquina lag deposit that comprises the basalmost Midway Group and also contains an abundance of other reptiles, as well as chondri...

Since the early l990s the Chicxulub crater on Yucatan, Mexico, has been hailed as the smoking gun that proves the hypothesis that an asteroid killed the dinosaurs and caused the mass extinction of many other organisms at the Cretaceous-Tertiary (K-T) boundary 65 million years ago. Here, we report evidence from a previously uninvestigated core, Yaxcopoil-1, drilled within the Chicxulub crater, i...

Angiosperms evolved rapidly in the late Mesozoic. Data from the genetic-based approach called ’molecular clock’ permit an evaluation of the radiation of flowering plants through geological time and of the possible influences of Mesozoic mass extinctions. A total of 261 divergence ages of angiosperm families are considered. The radiation of flowering plants peaked in the Albian, early Campanian,...

in this research, calcareous nannofossils of the upper cretaceous deposits of the souteast lar have been investigated. the upper cretaceous deposits have a thickness of 173 meters and consist of thick layers of marl and marly limestone. for introducing calcareous nannofossil assemblages and biozones, 141 slides of the gurpi formation in southeast of lar area have been studies which led to ident...