نتایج جستجو برای: cretaceous
تعداد نتایج: 9055 فیلتر نتایج به سال:
Australian dinosaurs have played a rare but controversial role in the debate surrounding the effect of Gondwanan break-up on Cretaceous dinosaur distribution. Major spatiotemporal gaps in the Gondwanan Cretaceous fossil record, coupled with taxon incompleteness, have hindered research on this effect, especially in Australia. Here we report on two new sauropod specimens from the early Late Creta...
The effect of the Cretaceous-Paleogene (K-Pg) (formerly Cretaceous-Tertiary, K-T) mass extinction on avian evolution is debated, primarily because of the poor fossil record of Late Cretaceous birds. In particular, it remains unclear whether archaic birds became extinct gradually over the course of the Cretaceous or whether they remained diverse up to the end of the Cretaceous and perished in th...
The rock strata of Cretaceous sedimentary system represented by Aptian to Maastrichtian age occurs as isolated patches outcropping in the western margin of the Cauvery Basin bordering the Archaean granite and gneiss basement. The Cretaceous system is well known as “Cretaceous of Trichinopoly” containing diverse fauna and flora including dinosaur remains, commercially exploitable limestone, lign...
Living reef fishes are one of the most diverse vertebrate assemblages on Earth. Despite its prominence and ecological importance, the origins and assembly of the reef fish fauna is poorly described. A patchy fossil record suggests that the major colonization of reef habitats must have occurred in the Late Cretaceous and early Palaeogene, with the earliest known modern fossil coral reef fish ass...
A worker ant preserved with microscopic detail has been discovered in Turonian-aged New Jersey amber [ca. 92 mega-annum (Ma)]. The apex of the gaster has an acidopore and, thus, allows definitive assignment of the fossil to the large extant subfamily Formicinae, members of which use a defensive spray of formic acid. This specimen is the only Cretaceous record of the subfamily, and only two othe...
Abelisauroid predators have been recorded almost exclusively from South America, India and Madagascar, a distribution thought to document persistent land connections exclusive of Africa. Here, we report fossils from three stratigraphic levels in the Cretaceous of Niger that provide definitive evidence that abelisauroid dinosaurs and their immediate antecedents were also present on Africa. The f...
The rise of angiosperms has been regarded as a trigger for the Cretaceous revolution of terrestrial ecosystems. However, the timeframe of the rise angiosperm-dominated herbaceous floras (ADHFs) is lacking. Here, we used the buttercup family (Ranunculaceae) as a proxy to provide insights into the rise of ADHFs. An integration of phylogenetic, molecular dating, ancestral state inferring, and dive...
Calcareous nannofossil assemblages recovered from a long, continuous section have been described from the Sarayan region in Lut Block in east Iran. The marine Upper Cretaceous sediments of this section yield medium diverse and well-preserved calcareous nannofossil assemblages. A structural analysis of Upper Cretaceous calcareous nannofloras has revealed 30 nannofossil species. A revised zonatio...
The first flowering plant fossils occur as rare, undiverse pollen grains in the Early Cretaceous (Valanginian-Hauterivian). Angiosperms diversified slowly during the Barremian-Aptian but rapidly during the Albian-Cenomanian. By the end of the Cretaceous, at least half of the living angiosperm orders were present, and angiosperms were greater than 70% of terrestrial plant species globally. The r...
Paleontologists long have argued that the most important evolutionary radiation of mammals occurred during the early Cenozoic, if not that all eutherians originated from a single common post-Cretaceous ancestor. Nonetheless, several recent molecular analyses claim to show that because several interordinal splits occurred during the Cretaceous, a major therian radiation was then underway. This c...
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