Wood anatomy of Late Triassic trees in Petrified Forest National Park, Arizona, USA, in relation to Araucarioxylon arizonicum Knowlton, 1889


Authors: Savidge RA

Published in: Bulletin of Geosciences, volume 82, issue 4; pages: 301 - 328; Received 5 April 2007; Accepted in revised form 16 July 2007;

Keywords: Triassic, Pinophyta, Araucaria-type wood, North America, oculipore, Protopiceoxylon novum, ray, resin canal, resinous tracheid, secondary xylem, tracheidoxyl, new taxa,

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Thin sections from the three syntypes of Araucarioxylon arizonicum Knowlton, 1889 were re-examined and found to be anatomically distinct. Two of the syntypes are similar and, considering Araucarioxylon (“Araucaroxylon”) Kraus, 1870 as nomen superfluum, those two are placed in Pullisilvaxylon gen. n. as nomen novum (lectotype Pullisilvaxylon arizonicum). The third specimen, known as the ‘Sherman log’, is transferred to Chinleoxylon knowltonii gen. et sp. n. Permineralized woods in three randomly sampled large-diameter logs assumed to be A. arizonicum plesiotypes were found to be anatomically distinct, two being species within Silicisilvaxylon gen. n., the third named Crystalloxylon imprimacrystallum gen. et sp. n. Thus, following descriptions of Arboramosa semicircumtrachea Savidge & Ash, 2006, Protocupressinoxylon arizonicum Savidge, 2006, and Ginkgoxylpropinquus hewardii Savidge, 2006, this study further increases the region’s number of woody plant morphotaxa and indicates that a diversity of large conifer species were co-evolving with cycads and ginkgo-like trees during Late Triassic.


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