compared to quartz sand, the shear behavior of carbonate sand differs in  appearance, origin, and kind. carbonate sand is found mainly in the northern coast of the persian gulf and the oman sea. in this research, a comparison is made between the shear behavior of carbonate sand retrieved from the eastern region of the chabahar port, located north of the oman sea, and quartz sand obtained from f...

We compare the deformation patterns produced by sand and a sand mica mixture (14:1 ratio of sand to mica by weight) while simulating basin fill in extension and inversion models to analyze the potential of the sand mica mixture for applications that require a strong elasto-frictional plastic analogue material in physical models. Sand and the sand mica mixture have nearly equal angles of interna...

Ichthyosaurs were important marine predators in the Early Jurassic, and an abundant and diverse component of Mesozoic marine ecosystems. Despite their ecological importance, however, the Early Jurassic species represent a reduced remnant of their former significance in the Triassic. Ichthyosaurs passed through an evolutionary bottleneck at, or close to, the Triassic-Jurassic boundary, which red...

An important innovation in the geosciences is the astronomical time scale. The astronomical time scale is based on the Milankovitch-forced stratigraphy that has been calibrated to astronomical models of paleoclimate forcing; it is defined for much of Cenozoic-Mesozoic. For the Palaeozoic era, however, astronomical forcing has not been widely explored because of lack of high-precision geochronol...

Large-bodied suspension feeders (planktivores), which include the most massive animals to have ever lived, are conspicuously absent from Mesozoic marine environments. The only clear representatives of this trophic guild in the Mesozoic have been an enigmatic and apparently short-lived Jurassic group of extinct pachycormid fishes. Here, we report several new examples of these giant bony fishes f...

Exceptionally preserved fossils—i.e., those that retain, in somemanner, labile components of organisms that are normally degraded far too quickly to enter the fossil record—hold the greatest potential for understanding aspects of the biology of long-extinct animals and are the best targets for the search for endogenous biomolecules. Yet the modes of preservation of these labile components, and ...

There are several types of firing tests of cannonballs. In ground firing tests, cannonballs without gunpowder charged are fired against sand heap. When a cannonball collides into sand, the cannonball’s penetration depth, stress and sand temperature depend on the sand properties. Sand tends to become harder than before after plenty of cannonball firing. This is because kinetic energy of a cannon...

An algorithm for simulating wind-ripples and moving sand is extended by the detection of fixed objects. This permits us simulation and animation of sand interacting with objects like houses, highways, cactuses, etc. Sand is accumulated on the windward side of an obstacle and the sand relocation and wind-ripples formation is diminished on the leeward side. The wind shadow depends on the object’s...

Variation in the geographic spread of fossil localities strongly biases inferences about the evolution of biodiversity, due to the ubiquitous scaling of species richness with area. This obscures answers to key questions, such as how tetrapods attained their tremendous extant diversity. Here, we address this problem by applying sampling standardization methods to spatial regions of equal size, w...

■ Abstract Vertebrate dispersal of fruits and seeds is a common feature of many modern angiosperms and gymnosperms, yet the evolution and frequency of this feature in the fossil record remain unclear. Increasingly complex information suggests that (a) plants had the necessary morphological features for vertebrate dispersal by the Pennsylvanian, but possibly in the absence of clear vertebrate di...