- Araucarioxylon arizonicum
Taxobox
name = "Araucarioxylon arizonicum"
fossil_range =Triassic
image_width = 240px
image_caption = Petrified "Araucarioxylon arizonicum"
regnum =Plant ae
divisio =Pinophyta
classis = Pinopsida
ordo =Pinales
familia =Araucariaceae
genus = "Araucarioxylon "
species = "A. arizonicum"
binomial = "Araucarioxylon arizonicum"
binomial_authority = Knowlton"Araucarioxylon arizonicum" is an extinct
conifer that is thestate fossil ofArizona .In the
Triassic period, the Araucarioxylon tree grew in what today's Black Forest, a part of the 378.51 km² (93,492 acre)Petrified Forest National Park in eastern Arizona. Prehistoric Arizona was a flat tropical expanse in the northwest corner of thesupercontinent Pangaea .The trees towered as high as 60 m (200 ft) and measured more than 60 cm (2 ft) in diameter. Fossils frequently show boreholes of
insect s, as well as fossilized hives of prehistoricbee s.The genus "Araucarioxylon" is regarded by some paleobotanists as synonymous with the modern genus "
Araucaria ", though this view is not universal.The
petrified wood of this tree is frequently referred to as "Rainbow wood" because of the large variety of colors somespecimen s exhibit. The red and yellow are produced by large particulate forms ofiron oxide , the yellow beinglimonite and the red beinghematite . The purple hue comes from extremely fine spherules of hematite distributed throughout thequartz matrix, and not frommanganese , as has sometimes been suggested.References
* F. H. Knowlton, New species of fossil wood ("Araucarioxylon arizonicum") from Arizona and New Mexico, "Proceedings of the United States National Museum", 1889.
* [http://www.smithsonianmag.com/science-nature/object_june97.html Smithsonian Magazine article on "A. arizonicum"]
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