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end-Permian Mass Extinction (end-permian + mass_extinction)
Selected AbstractsTHE END-PERMIAN MASS EXTINCTION WAS SYNCHRONOUS COINCIDED WITH THE EVOLUTION OF TOXIC ALGAEJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Lee, R. E.1 & Kugrens, P.2 1Department of Biomedical Sciences, College of Veterinary Medicine, Colorado State University, Fort Collins, CO 80523; 2Department of Biology, Colorado State University, Fort Collins, Co 80523 USA The cause of the end-Permian mass extinction, the greatest of all mass extinctions, is one of the most intriguing mysteries in the history of life. The end-Permian mass extinction was primarily a marine event, resulting principally in the elimination of sessile filter-feeding organisms. Based on two methods, molecular clocks and correlation with ancient atmospheric CO2, the algae derived from secondary endosymbioses are believed to have originated in the middle to late Permian. All of the toxic marine algae in today's oceans are derived from secondary endosymbioses. Therefore it appears likely that the end-Permian extinction was due to the evolution of toxic algae in the phytoplankton of late-Permian seas. Sieving of the toxic algae in the phytoplankton likely resulted in the decline and eventual elimination of a large portion of the Paleozoic fauna during the end-Permian mass extinction. [source] End-Permian mass extinction: oceanographic consequences of double catastrophic volcanismLETHAIA, Issue 3 2003GRZEGORZ RACKI No abstract is available for this article. [source] THE END-PERMIAN MASS EXTINCTION WAS SYNCHRONOUS COINCIDED WITH THE EVOLUTION OF TOXIC ALGAEJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Lee, R. E.1 & Kugrens, P.2 1Department of Biomedical Sciences, College of Veterinary Medicine, Colorado State University, Fort Collins, CO 80523; 2Department of Biology, Colorado State University, Fort Collins, Co 80523 USA The cause of the end-Permian mass extinction, the greatest of all mass extinctions, is one of the most intriguing mysteries in the history of life. The end-Permian mass extinction was primarily a marine event, resulting principally in the elimination of sessile filter-feeding organisms. Based on two methods, molecular clocks and correlation with ancient atmospheric CO2, the algae derived from secondary endosymbioses are believed to have originated in the middle to late Permian. All of the toxic marine algae in today's oceans are derived from secondary endosymbioses. Therefore it appears likely that the end-Permian extinction was due to the evolution of toxic algae in the phytoplankton of late-Permian seas. Sieving of the toxic algae in the phytoplankton likely resulted in the decline and eventual elimination of a large portion of the Paleozoic fauna during the end-Permian mass extinction. [source] Complex behavioural pattern as an aid to identify the producer of Zoophycos from the Middle Permian of OmanLETHAIA, Issue 2 2009DIRK KNAUST The trace fossil Zoophycos is abundant in transgressive, shallow marine carbonates in the Middle Permian (Wordian) Khuff Formation of the Huqf-Haushi Uplift of Interior Oman. It often occurs as part of a complex (compound) trace fossil that comprises two integrated elements: (i) irregular galleries with straight to gently curved tunnels and interconnected shafts, and (ii) simple planar to complex spreiten structures with a marginal tube (Zoophycos). The galleries are characterized by irregularly winding, dichotomous branching, large variation in shape and size and circular to elliptical vertical cross-sections. Zoophycos consists of spreiten with a marginal tube, either originating as a simple lobe from the convex segment of a curved tunnel, or forming more complex, subcircular, spreiten systems parallel to bedding. The spreiten were formed by simple strip mining, where the animal defecated without producing faecal pellets. U-shaped marginal tubes indicate that the burrows were well aerated. The complex trace fossil points to combined dwelling and deposit-feeding behaviour, with irregular galleries in the firm substrate and Zoophycos spreiten in the softground below it. It can be assumed that the animal used the open tunnel system mainly for dwelling (domichnion) and possibly suspension feeding, but occasionally changed to deposit feeding while creating the spreiten (fodinichnion). The integration of the irregular galleries (tunnels and interconnected shafts) with the marginal tubes of Zoophycos suggests the same producer for this compound trace fossil. Many modern polychaetes produce very similar galleries within firm and soft substrates, and polychaetes are therefore interpreted as the most likely producers. Similarities between Permian and Triassic Zoophycos suggest comparable trace making behaviour before and after the end-Permian mass extinction. [source] Lystrosaurus species composition across the Permo,Triassic boundary in the Karoo Basin of South AfricaLETHAIA, Issue 2 2007JENNIFER BOTHA Lystrosaurus is one of the few therapsid genera that survived the end-Permian mass extinction, and the only genus to have done so in abundance. This study identifies which species of Lystrosaurus have been recovered from Permian and Triassic strata to determine changes in the species composition across the Permo,Triassic (P,T) boundary in the Karoo Basin of South Africa. Data generated from museum collections and recent fieldwork were used to stratigraphically arrange a total of 189 Lystrosaurus specimens to determine which species survived the extinction event. Results reveal that L. curvatus and L. maccaigi lived together on the Karoo floodplains immediately before the extinction event. L. maccaigi did not survive into the Triassic in South Africa. L. curvatus survived, but did not flourish and soon became extinct. Two new species of Lystrosaurus, L. murrayi and L. declivis, appeared in the Early Triassic. It is possible that L. murrayi and L. declivis occupied different niches to L. maccaigi and L. curvatus, and had special adaptations that were advantageous in an Early Triassic environment. We suggest that L. maccaigi may be used as a biostratigraphic marker to indicate latest Permian strata in South Africa and that, in support of previous proposals, the genus Lystrosaurus should not be used as a sole indicator of Triassic-aged strata. Our field data also show that L. curvatus may be regarded as a biostratigraphic indicator of the P,T boundary interval. [source] Biodiversity and Sequence of the Middle Triassic Panxian Marine Reptile Fauna, Guizhou Province, ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2009Dayong JIANG Abstract: The Middle Triassic Panxian fauna is a physical marker and representative record of the rapid recovery of the Triassic marine ecosystem following the Early Triassic stagnant stage after the end-Permian mass extinction. Ten marine reptile taxa have been found from the 1.82,2.10 m-thick fossiliferous level in the Upper Member of the Guanling Formation, which can be subdivided into three marine reptile beds through the analysis on the stratigraphic distributions of fossil reptiles. The Lower Reptile Bed yields the sauropterygians Placodus inexpectatus Jiang et al., 2008 and Lariosaurus hongguoensis Jiang et al., 2006, the ichthyopterygians Xinminosaurus catactes Jiang et al., 2008 and Phalarodon cf. Phalarodon fraasi Merriam, 1910, associated with Mixosaurus panxianensis Jiang et al., 2006, representing a stage of predominance of durophagous taxa. In this bed, the large complete skeletons may reach up to 2.3 m in length, and lithofacies and chemostratigraphic analyses indicate a relatively deep carbonate platform with an oxic water environment near the bottom, as well as a rising sea level. The Middle Reptile Bed yields the sauropterygian Nothosaurus yangjuanensis Jiang et al., 2006 and the archosaur Qianosuchus mixtus Li et al., 2006, associated with Mixosaurus panxianensis Jiang et al., 2006. The fossils in this bed are characterized by its pincering dentition and large overall body size, with the largest possibly exceeding 3 m in length. This bed might represent a time of deepest basin with relatively anoxic condition near the bottom. The Upper Reptile Bed yields the sauropterygians Wumengosaurus delicatomandibularis Jiang et al., 2008, Keichousaurus sp., the protorosaur Dinocephalosaurus orientalis Li, 2003, and the ichthyopterygian Mixosaurus panxianensis Jiang et al., 2006. In this bed, reptilian taxa characterized by suction feeding appeared, and most are less than 1 m long. This bed corresponds to a period of decreasing water depth. [source] | ||||||||||