BACKGROUND We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. METHODOLOGY/PRINCIPAL FINDINGS The PO(2) of modern normoxic seawater is 21 kPa (air-equilibrated water), a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna....

The taxonomy of simply deformed paradoxidids from the Miaolingian (Cambrian) Slowiec Hill, Holy Cross Mountains, Poland, is revised based on morphometric analysis. material represents two species: Acadoparadoxides slowiecensis (Czarnocki in Orlowski, 1965) and Hydrocephalus ? polonicus 1965). A new assemblage zone combined although not precisely known ranges these taxa suggested replacing previ...

The Cambrian radiation represents an interval when nearly 20 animal phyla appear in the fossil record in a short geological time span; however, whether this radiation also represents a period of extremely rapid speciation remains unclear. Here, a stochastic framework is used to test the null hypothesis that diversity changes in one of the dominant Early Cambrian groups, the olenelloid trilobite...

Charles Darwin suspected that the Cambrian “explosion” might be an artifact of fossil preservation. A more recent, initially controversial hypothesis that repeated true polar wander (TPW) triggered the Ediacaran-Cambrian explosion of animal life has been supported by numerous paleomagnetic and geochronologic refinements. These data imply 75° of TPW between 535 and 515 million years ago, coincid...