American Journal of Botany 84(3): 343–354. 1997. A TAXODIACEOUS SEED CONE FROM THE TRIASSIC OF
A silicified seed cone is described from the lower Middle Triassic of Antarctica. The cone measures up to 3.4 cm long and 1.4 cm wide, and consists of helically arranged cone scales attached to a eustelic axis. Bract and ovuliferous scale are approximately of equal length and fused at the base. The...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.512.3216 http://www.amjbot.org/content/84/3/343.full.pdf |
| Summary: | A silicified seed cone is described from the lower Middle Triassic of Antarctica. The cone measures up to 3.4 cm long and 1.4 cm wide, and consists of helically arranged cone scales attached to a eustelic axis. Bract and ovuliferous scale are approximately of equal length and fused at the base. The bract is entire and vascularized by a single trace. The ovuliferous scale contains five distal lobes, each vascularized by a terete strand that divides to form a smaller trace to each of the five inverted ovules. Ovules are small and flattened with the three-parted integument attenuated into oppositely positioned lateral wings. The Triassic specimens are compared with both extant and fossil conifer seed cones and believed to have their closest affinities within the Taxodiaceae. Key words: bract; ovule; ovuliferous scale; Parasciadopitys; seed cone; Taxodiaceae; Triassic; vasculature. Permineralized seed cones have contributed signifi-cantly to our understanding of conifer evolution by pro-viding anatomical details that have been useful in deter-mining homologies among components of reproductive axes. Permineralized conifer seed cones of Paleozoic age have been reported only from the Northern Hemisphere |
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