Isoetes beestonii

Isoetes beestonii; Temporal range: Late Permian PreꞒ Ꞓ O S D C P T J K Pg N
	Complete plant of Isoetes beestonii from latest Permian Coalcliff Sandstone in South Bulli Colliery, NSW, Australia.
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Lycophytes
Class:	Lycopodiopsida
Order:	Isoetales
Family:	Isoetaceae
Genus:	Isoetes
Species:	†I. beestonii
Binomial name
	†Isoetes beestonii; Retallack

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]

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.

References

^ ^a ^b ^c 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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[Retallack1997-1] Retallack, Gregory J. (1997). "Earliest Triassic origin of Isoetes and quillwort evolutionary radiation". Journal of Paleontology. 7 (3): 500–521.

[Retallack2013-2] Retallack, Gregory J. (2013). "Permian and Triassic greenhouse crises". Gondwana Research. 24: 90–103. doi:10.1016/j.gr.2012.03.003.

[1]

[2]

Description

See also

References