Araucaria mirabilis
Araucaria mirabilis | |
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Fossilized branch and cones of Araucaria mirabilis from Cerro Cuadrado, Patagonia, Argentina | |
Paläontologisches Museum München
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Gymnospermae |
Division: | Pinophyta |
Class: | Pinopsida |
Order: | Araucariales
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Family: | Araucariaceae |
Genus: | Araucaria |
Species: | †A. mirabilis
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Binomial name | |
†Araucaria mirabilis (
Spegazzini) Windhausen (1924) | |
Location of the Cerro Cuadrado Petrified Forest in Patagonia, Argentina | |
Synonyms[1][2] | |
Araucaria mirabilis is an
.A. mirabilis are known from large amounts of very well preserved silicified wood and cones from the Cerro Cuadrado Petrified Forest, including tree trunks that reached 100 m (330 ft) in height in life. The site was buried by a volcanic eruption during the Middle Jurassic, approximately 160 million years ago.
Discovery
Fossils of Araucaria mirabilis are found in great abundance in the Cerro Cuadrado Petrified Forest of Patagonia, Argentina.[3][4] They were the dominant species of a forest buried by a volcanic eruption about 160 million years ago.[5]
The petrified forests of A. mirabilis were first discovered in 1919 by the
However, the
An
An amended description was published by the Scottish paleobotanist Mary Gordon Calder in 1953. Calder questioned the conclusions of Wieland and Gothan. She also discarded the earlier classification of Spegazzini of Araucarites. The latter is a form genus, usually used for incomplete plant fossil specimens that resemble Araucaria but lack enough preserved details for more accurate classifications. Citing striking similarities with the extant Araucaria bidwillii, Calder reclassified the specimens as Araucaria mirabilis.[2]
Taxonomy and nomenclature
Araucaria mirabilis belongs to the genus Araucaria. It is classified under the family Araucariaceae of the order Pinales. Its has previously been assigned to the section Bunya of Araucaria, which contains the living Australian bunya-bunya (Araucaria bidwillii).[6][7] However, this has subsequently been questioned, with other studies finding it to have a basal position within Araucaria.[8]
The genus name Araucaria is derived from the
Description
A large number of
The cones are spherical, ovoid to ellipsoidal in shape, with a wide axis. They average 2.5 to 8 cm (0.98 to 3.15 in) in length.[7] The largest specimens are nearly 10 cm (3.9 in) in diameter.[6] The center of the cones consist of a parenchymatous pith surrounded by fused vascular bundles (two for each bract-scale complex, with each vascular bundle containing resin canals).[6][7]
The bracts have thick and wide woody wings tapering towards the base. They are around 13 to 16 mm (0.51 to 0.63 in) long and 10 mm (0.39 in) wide, including the wings.[2] They are overlain by fertile scales containing one seed each, embedded on the upper surface.[11] They are arranged helically.[6] The "ligules" (the free tip of the fertile scale characteristic of Araucaria) are 4 mm (0.16 in) wide, 1 to 2 mm (0.039 to 0.079 in) high, and 5 mm (0.20 in) long.
The mature seeds of A. mirabilis are about 0.8 to 1.3 cm (0.31 to 0.51 in) long and 0.2 to 0.6 cm (0.079 to 0.236 in) wide.
Small woody corm-like structures have also been found. Initially identified as "seedlings", are now known to be lignotubers.[7][11]
Paleobiology and paleoecology
A. mirabilis exhibits two characteristics shared only by A. bidwillii among extant Araucaria species. First is the separate origins of the vascular bundles of the bract and fertile scales; second is the highly vascularized "ligule".[2] They also both have dicotyledonous embryos. On this basis, A. mirabilis is classified as belonging to the section Bunya.[11][13]
However, the seeds of A. bidwillii are much larger, 5 to 6 cm (2.0 to 2.4 in) long and 2.5 to 3.5 cm (0.98 to 1.38 in) wide, than the seeds of A. mirabilis.
A. mirabilis is found in association with other
The fossils of the putative
It is believed that the long necks of
A. mirabilis fossils have been found with damage resulting from beetle larvae. These beetles are believed to be the ancestors of the most ancient lineage of bark beetles in the weevil family (Curculionidae) - the members of the tribe Tomicini, which are still serious pests of conifers today. They were probably host-specific to members of the genus Araucaria since the Mesozoic.[19][20] Modern A. bidwillii are also hosts to primitive weevils from the family Megalopodidae and leaf beetles from the family Nemonychidae.[21]
Distribution and geologic time range
Araucaria forests were distributed globally and formed a major part of the woody flora of the
See also
References
- ^ Pedro N. Stipanicic; Osvaldo A. Reig (1955). "Breve noticia sobre el hallazgo de anuros en el denominado (completo porfirico de la Patagonia extraandina) con consideraciones acerca de la composicion geologica del mismo". Revista de la Asociación Geológica Argentina (in Spanish). 10 (4): 215–233.
- ^ doi:10.1038/173243b0.
- ^ S2CID 53975045.[permanent dead link]
- ^ PMID 21729086.[permanent dead link]
- ^ a b Linda Klise; Leo J. Hickey (2003). "Petrified wood: rainbows in stone" (PDF). Yale Environmental News. 9 (1): 19.
- ^ ISBN 978-0-12-373972-8.
- ^ S2CID 142881356. Archived from the original(PDF) on 2012-04-02.
- PMID 32705687.
- ^ Christopher J. Earle (December 12, 2010). "Araucaria Jussieu 1789". The Gymnosperm Database. Retrieved November 13, 2011.
- ISBN 978-0-907567-62-2.
- ^ a b c d Mary E. Dettmann; H. Trevor Clifford (2005). "Biogeography of Araucariaceae" (PDF). In J. Dargavel (ed.). Australia and New Zealand Forest Histories. Araucaria Forests. Occasional Publication 2. Australian Forest History Society. pp. 1–9.
- ^ PMID 21680310.
- ^ a b c Ruth A. Stockey (1980). "Jurassic araucarian cone from Southern England" (PDF). Palaeontology. 23 (3): 657–666.
- ISBN 978-0-12-080263-0.
- ^ .
- .
- PMID 21708655.
- PMID 18252667.
- ^ PMID 11133024.
- ISSN 0024-4066.
- PMID 9677197. Archived from the original(PDF) on 2012-04-07.