Paleobiology; September 2001; v. 27; no. 3;
p. 531-538; DOI: 10.1666/0094-8373(2001)027<0531:AMWGRC>2.0.CO;2
© 2001 Paleontological Society
Are Mesozoic wood growth rings climate-induced?
Anne-Lise Brison1,
Marc Philippe2,3 and
Frédéric Thevenard2
1 Anne-Lise Brison. Laboratoire de Paléobotanique de l'Université Lyon-1, 7 rue Dubois, F69622 Villeurbanne cedex, France
2 Marc Philippe* and Frédéric Thevenard, Laboratoire de Paléobotanique de l'Université Lyon-1 and FRE2158 du CNRS, 401A, 7 rue Dubois, F69622 Villeurbanne cedex, France. philippe{at}univ-lyon1.fr
3 *Corresponding author
Growth rings of Mesozoic fossil woods have often been used for paleoclimatological inferences. Most of the studies, however, rest upon uniformitarian deductions based on the observation of conifers from the present boreal temperate realm, whereas warm climates dominated during the Mesozoic. We propose a new approach, based on the study of the distribution of growth ring types among 643 samples from the JurassicCretaceous interval. A clear picture emerges from analysis, consistent with what is known of Mesozoic climates from other sources. Woods with no rings are encountered in a wide latitudinal zone, extending up to 75°N and 65°S during the Late Cretaceous. Woods with well-developed latewood do not occur at low latitude and disappeared from the Northern Hemisphere during the Late Cretaceous. Our data set also shows that the taxonomic distribution of growth ring types is not regular. Among the genera encountered, 40% can build only one type of ring. The genus Agathoxylon never displays thick latewood, although it ranges from 75°S to 70°N. This demonstrates that growth ring studies must include a taxonomic analysis.
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