We summarize information concerning Recent and Pleistocene-Holocene Uruguayan sand dollars (Mellitidae), as well as Miocene taxa (Monophorasteridae). Recent and Pleistocene-Holocene species (Encope emarginata, Mellita quinquiesperforata, and Leodia sexisperforata) are at their southernmost limits of distribution, with only E. emarginata recorded further south than Uruguay. Lower temperatures to...

Many larvae and other plankton have complex and variable morphologies of unknown functional significance. We experimentally and theoretically investigated the functional consequences of the complex morphologies of larval sand dollars, Dendraster excentricus (Eschscholtz), for hydrodynamic interactions between swimming and turbulent water motion. Vertical shearing flows (horizontal gradients of ...

Sedimentologic, stratigraphic, and geochronologic data from strata of early Mesozoic age in the central Mojave block elucidate the paleogeographic and tectonic evolution of the magmatic arc in the southern U.S. Cordillera. A sequence of calcareous siltstone, volcaniclastic conglomerate, tuff, and quartzose sandstone records the transition from shallow-marine rocks of the Fairview Valley Formati...

Footprints of the rhea (Rhea ameriama) are identical in several diagnostic features to tridactyl footprints of the Mesozoic Era attributed to theropod dinosaurs. Of particular interest,'(i) the rhea's feet are placed very close to its body midline as it walks, so that it virtually places one foot in front of the other; (ii) its middle toe (digit III), the central weight-bearing axis, is directe...

--___-___-__„___-_-_______________________ Introduction.. _ _____________________________________ Stratigraphic Summary__________________________ Mesozoic and older rocks in Esso Standard Oil Co. Hatteras Light well No. 1___________________ Mesozoic rocks in Esso Standard Oil Co. North Carolina Esso well No. 2______________________ Stratigraphic distribution of the Ostracoda________ Systematic ...

Sand dripping in 1 dimensional Sand Pile Model is rst studied. Patterns and signals appear. Their behaviors and interactions are explained and asymptotic approximations are made. The total collapsing time of a single stack of sand is linear in function of the number of grains.