The time of origin of the animal phyla is controversial. Abundant fossils from the major animal phyla are found in the Cambrian, starting 544 million years ago. Many paleontologists hold that these phyla originated in the late Neoproterozoic, during the 160 million years preceding the Cambrian fossil explosion. We have analyzed 18 protein-coding gene loci and estimated that protostomes (arthrop...

13 Ž . New records of the abundance of C in marine organic matter have been compiled for i the later Neoproterozoic, from Ž . Ž . Ž . Ž . 800 to 543 Ma 346 analyses , ii the Cambrian through the Jurassic 1616 analyses , and iii the Cretaceous and Cenozoic Ž . 13 2493 analyses . Comparison of these to existing compilations of the abundance of C in sedimentary carbonates has Ž . allowed developme...

, 65, 85–87.Prasad, N. and Roscoe, S.M., 1996. Evi-dence for anoxic to oxic atmosphericchange during 2.45–2.22 Ga from lowerand upper sub-Huronian paleosols.Catena, 27, 105–121.Prave, A.R., 1999a. Two diamictites, twocap carbonates, two dC excursions,two rifts: the Neoproterozoic KingstonPeak Formation, Death Valley, Califor-nia. Geology, 27, 339–342....

, 65, 85–87.Prasad, N. and Roscoe, S.M., 1996. Evi-dence for anoxic to oxic atmosphericchange during 2.45–2.22 Ga from lowerand upper sub-Huronian paleosols.Catena, 27, 105–121.Prave, A.R., 1999a. Two diamictites, twocap carbonates, two dC excursions,two rifts: the Neoproterozoic KingstonPeak Formation, Death Valley, Califor-nia. Geology, 27, 339–342....

We report new discoveries of embryos and egg capsules from the Lower Cambrian of Siberia, Middle Cambrian of Australia and Lower Ordovician of North America. Together with existing records, embryos have now been recorded from four of the seven continents. However, the new discoveries highlight secular and systematic biases in the fossil record of embryonic stages. The temporal window within whi...

to assess biogeographic affinity of the late cambrian (furongian) and the early ordovician (late tremadocian) faunas of eastern alborz, a multivariate cluster analysis using the pair-group raup-crick similarity index has been applied. the late cambrian fauna of alborz shows clear gondwanan signatures with the closest affinities to the contemporaneous faunas of temperate latitude peri-gondwana (...

Overview The paleogeographic reconstruction of the late Neoproterozoic assumes a marked significance due to the fact that the interactions between the biosphere, atmosphere, hydrosphere, and geosphere during this time strongly influenced the evolution of life and initiated a remarkable phase of organic evolution, well documented in the rocks of this age. Time-related changes in these carbon res...

The Pelona, Orocopia, and Rand Schists and the schists of Portal Ridge and Sierra de Salinas constitute a high–pressure-temperature terrane that was accreted beneath North American basement in Late Cretaceous–earliest Tertiary time. The schists crop out in a belt extending from the southern Coast Ranges through the Mojave Desert, central Transverse Ranges, southeastern California, and southwest...

It has recently been found that Neoproterozoic glaciogenic sediments were deposited mainly at low paleolatitudes, in marked qualitative contrast to their Pleistocene counterparts. Several competing models vie for explanation of this unusual paleoclimatic record, most notably the high-obliquity hypothesis and varying degrees of the snowball Earth scenario. The present study quantitatively compil...