See more from this Division: Topical Sessions
See more from this Session: Recoveries from Mass Extinction: Patterns, Processes, and Comparisons II
Abstract:
Ammonoid diversity was lowest during the Griesbachian and increased slowly during the Dienerian. In the early Smithian (Flemingites beds) diversity rapidly increased and remained high (~30 genera per zone) until the late middle Smithian (Inyoites beds). This first diversification phase occurred no later than 2my after the PTB and ended with a major extinction in the late Smithian (Anasibirites beds, Glyptophiceras beds). A longer-lived phase of diversity rebound occurred shortly after, during the Spathian.
This global diversity pattern is closely associated with major perturbations of the global carbon cycle [6-8]. The late Smithian - early Spathian time interval is marked by a prominent positive δ13C shift. As indicated by drastic changes in the latitudinal gradient of generic richness of ammonoids [1] and the boreal palynological record [8], Early Triassic times experienced severe climatic changes. CO2 degassing via volcanism of hypothetical late eruptive phases of the Siberian Traps has been proposed as a trigger for these global disturbances [5].
[1] Brayard, A. et al. 2006: PPP 239.
[2] Brayard, A. & Bucher, H. 2008: Fossils & Strata 55.
[3] Brühwiler, T. et al. 2007a: NMNH Bull. 41.
[4] Galfetti, T. et al. 2007a: EPSL 258.
[5] Ovtcharova, M. et al. 2006: EPSL 243.
[6] Brühwiler, T. et al. 2007b: SGM Geneva.
[7] Galfetti, T. et al. 2007b: PPP 243.
[8] Galfetti, T. et al. 2007c: Geology 35.
See more from this Division: Topical Sessions
See more from this Session: Recoveries from Mass Extinction: Patterns, Processes, and Comparisons II