Isoetes beestonii
Isoetes beestonii is the oldest known species of the living quillwort genus from the latest Permian of New South Wales and Queensland. Originally considered earliest Triassic,[1] it is now known to be latest Permian in age, immediately before the Permian Triassic mass extinction.[2]
| Isoetes beestonii | |
|---|---|
 | |
| Complete plant of Isoetes beestonii from latest Permian Coalcliff Sandstone in South Bulli Colliery, NSW, Australia.[1] | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Lycophytes |
| Class: | Lycopodiopsida |
| Order: | Isoetales |
| Family: | Isoetaceae |
| Genus: | Isoetes |
| Species: | †I. beestonii |
| Binomial name | |
| †Isoetes beestonii Retallack | |
Description
Isoetes beestonii is preserved as whole plants in life position within bedding planes, and presumably lived as an early successional weed in lake and pond sedimentary environments, like living Isoetes. Its leaves were wider and more succulent than modern species of Isoetes.[1] Like modern Isoetes, fertile plants were little different from sterile plants, unlike Early Triassic Tomiostrobus which formed woody conelike fertile plants.
Reconstructions of sterile and fertile examples of Isoetes beestonii from the latest Permian Coal Cliff Sandstone of South Bulli Colliery, NSW, and of Tomiostrobus australis from the Early Triassic Gosford Formation near Terrigal, NSW
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See also
- Evolution of plants
References
- Retallack, Gregory J. (1997). "Earliest Triassic origin of Isoetes and quillwort evolutionary radiation". Journal of Paleontology. 7 (3): 500–521.
- Retallack, Gregory J. (2013). "Permian and Triassic greenhouse crises". Gondwana Research. 24: 90–103. doi:10.1016/j.gr.2012.03.003.
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