نتایج جستجو برای: jurassic
تعداد نتایج: 4540 فیلتر نتایج به سال:
The Crossognathiformes is an extinct fish order erected by Taverne (1989) to contain the crossognathids and the pachyrhizodontoids, and until recently, considered a typical Cretaceous taxon. However, recent studies of the group have shown that the Jurassic family Varasichthyidae is the sister group of pachyrhizodontoids plus crossognathids extending the range of the group to the Oxfordian in th...
Apatite fission-track analysis was applied to Triassic and Cretaceous sediments from the South-Iberian Continental Margin to unravel its thermal history. Apatite fission-track age populations from Triassic samples indicate partial annealing and point to a maximum temperature of around 100–110 °C during their post-depositional evolution. In certain apatites from Cretaceous samples, two different...
T he production of acoustic signals is among the most important behaviors in animal communication, because sending and receiving messages using sound is essential for the survival and success of almost all kinds of animals. However, the reconstruction of the evolutionary history of acoustic performance is a major challenge. Using phylogenetic methods based on data from living animals is the mos...
The present article is a review of a palaeobiogeographic analysis of Jurassic Ostracods from East Africa, India and Madagascar and includes also some general remarks on palaeobiogeography, biodiversity and Ostracod ecology.The palaeobiogeographic study shows the high significance of this microfossil group for the reconstruction of palaeogeographic processes, particularly plate tectonic developm...
Moore, G.T., Sloan, L.C., Hayashida, D.N. and Umrigar, N.P., 1992. Paleoclimate of the Kimmeridgian/Tithonian (Late Jurassic) world: II. Sensitivity tests comparing three different paleotopographic settings. Palaeogeogr,, Palaeoclimatol., Palaeoecol., 95: 229-252. Topography and location of continents largely determine present-day climate. We conclude that in the geologic past paleotopographic ...
The fossil record is our only direct means for evaluating shifts in biodiversity through Earth's history. However, analyses of fossil marine invertebrates have demonstrated that geological megabiases profoundly influence fossil preservation and discovery, obscuring true diversity signals. Comparable studies of vertebrate palaeodiversity patterns remain in their infancy. A new species-level data...
Cretaceous ichthyosaurs have typically been considered a small, homogeneous assemblage sharing a common Late Jurassic ancestor. Their low diversity and disparity have been interpreted as indicative of a decline leading to their Cenomanian extinction. We describe the first post-Triassic ichthyosaur from the Middle East, Malawania anachronus gen. et sp. nov. from the Early Cretaceous of Iraq, and...
The extremes of dinosaur body size have long fascinated scientists. The smallest (<1 m length) known dinosaurs are carnivorous saurischian theropods, and similarly diminutive herbivorous or omnivorous ornithischians (the other major group of dinosaurs) are unknown. We report a new ornithischian dinosaur, Fruitadens haagarorum, from the Late Jurassic of western North America that rivals the smal...
Complete, articulated starfish fossils are rare. However, more frequently encountered dissociated skeletal elements (ossicles) permit reliable taxonomic identification, making them a valuable data source for diversity estimates. Nearly 300 asteroid ossicles, collected from the middle Toarcian marls in western France can be assigned to five species. Four species and two genera are described: Com...
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