Cen Shen et al. (Xi-guang Zhang, corresponding), Key Laboratory for Paleobiology, Yunnan University, Kunming, Yunnan 650091, China. Posted online 28 Nov. 2012; http://dx.doi.org/10.1130/G33763.1.
Chitinozoans, an enigmatic group of marine microorganisms, have long been discovered from the early Ordovician to the latest Devonian strata with a worldwide distribution. Usually their organic-walled tests may be preserved as individual vesicles, in aggregate masses, in chains, or associated with organic envelopes (cocoons), exhibiting a strikingly morphological diversification. These advantages have enabled this microfossil group to be successfully applied for biostratigraphic subdivision of the Paleozoic. However information about their origin and early evolution is sparse. With efficient collaboration, a team of paleontologists coming from three countries has reported the oldest hitherto known chitinozoan Eisenackitina? sp. from the Cambrian Stage 5 (~510 million years old) of China, extending the record of this group back by at least 20 million years. The exceptional occurrence of the Cambrian chitinozoan along with many other phosphatized fossils, including embryos in Orsten-type preservation, might imply a benthic mode of life for itself. This discovery not only supplies critical data for evaluation of the basic morphology of the Cambrian chitinozoans, but also sheds new light on assessment of their early evolutionary process.
Seismic reflection imaging of ultradeep roots beneath the eastern Aleutian island arc
Andrew J. Calvert (corresponding) and Susan E. McGeary, Department of Earth Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada. Posted online 28 Nov. 2012; http://dx.doi.org/10.1130/G33683.1.
Volcanic island arcs
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Geological Society of America