The Lower and Middle Cambrian age acritarch assemblages are reported from a continuous succession of the siliciclastic-carbonate Ribota, Huermeda Daroca Formations in Iberian Chains, northeastern Spain. One new genus four species described, one them open nomenclature. microfossil allow to recognize Heliosphaeridium dissimilare - Skiagia ciliosa Volkovia dentifera ­Liepaina plana zones, disc...

SYNOPSIS. The Cambrian radiation is that key episode in the history of life when a large number of animal phyla appeared in the fossil record over a geologically short period of time. Over the last 20 years, scientific understanding of this radiation has increased significantly. Still, fundamental questions remain about the timing of the radiation and also the tempo of evolution. Trilobites are...

Shell microstructures in some of the oldest known mollusk fossils (from the early to middle Cambrian Period; 542 to 510 million years ago) are diverse, strong, and in some cases unusual. We herein review our recent work focused on different aspects of shell microstructures in Cambrian mollusks, briefly summarizing some of the major conclusions from a few of our recent publications and adding so...

Recent geological work in south-west Tasmania on a regional scale has allowed the compilation of existing information regarding Lower Palaeozoic unconformities, namely the description of new localities and in some cases the amplification and extension of previously described exposures. Carey and Banks (1954, p. 245) provide a review of information to 1954 and their classification of unconformit...

Calcareous skeletons evolved as part of the greater Ediacaran/Cambrian diversification of marine animals; however, skeletons did not become permanent, globally important sources of carbonate sediment until the Ordovician radiation. Representative carbonate facies in a Series 3 Cambrian to Tremadocian succession from western Newfoundland and Ordovician successions from the Ibex area, Utah, show ...

Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540-520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is st...

In the most complete and first radiometrically dated Precambrian-Cambrian transition strata along the Khorbusuonka River in northern Siberia, a succession of fossilized traces of activity of the earliest infaunal animals has been identified. As supplemented by a similar record in Podolia, the Ukraine and elsewhere. This collection demonstrates that thus far all of the structurally identifiable ...