Corystosperms are a group of extinct seed plants belonging to the family Corystospermaceae assigned to the order Corystospermales[2] or Umkomasiales.[3] They were first described based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa.[4] Corystosperms are typified by a group of plants that bore Dicroidium leaves, Umkomasia ovulate structures and Pteruchus pollen organs, that were widespread over Gondwana during the Middle and Late Triassic. Other fossil Mesozoic seed plants with similar reproductive structures have also sometimes been included within the "corystosperm" concept sensu lato, such as the "doyleoids" from the Early Cretaceous of North America and Asia.[3] A potential corystosperm, the leaf fossil Komlopteris cenozoicus, is known from the Eocene of Tasmania, at least 13 million years after the Cretaceous–Paleogene extinction event.[5]
Umkomasiaceae have helmet-like cupules around ovules born in complex large branching structures (Umkomasia). The pollen organ (Pteruchus) has numerous cigar-shaped pollen sacs hanging from epaulette-like blades, again in complex branching structures.
Pteruchus africanus pollen structure from the Late Triassic, Molteno Formation of Umkomaas, South Africa
The leaves (Dicroidium) are tied to the fertile organs by similarities of cuticular structure, because their cuticles were robust like those of gymnosperms and unlike the thin leaves of ferns.
Dicroidium odontopteroides leaf from the Late Triassic, Molteno Formation of Birds River, South Africa
^Abu Hamad, A.; Blomenkemper, P.; Kerp, H.; Bomfleur, B. (December 2017). "Dicroidium bandelii sp. nov. (corystospermalean foliage) from the Permian of Jordan". PalZ. 91 (4): 641–648. doi:10.1007/s12542-017-0384-2. ISSN 0031-0220.
^ abShi, Gongle; Herrera, Fabiany; Herendeen, Patrick S.; Clark, Elizabeth G.; Crane, Peter R. (2022-12-31). "Silicified cupulate seed-bearing structures from the Early Cretaceous of eastern Inner Mongolia, China: rethinking the corystosperm concept". Journal of Systematic Palaeontology. 20 (1): 1–33. doi:10.1080/14772019.2022.2133644. ISSN 1477-2019. S2CID 253562726.
^Thomas, H.H. (1933). "On some pteridospermous plants from the Mesozoic rocks of South Africa". Philosophical Transactions of the Royal Society B. 222 (483–493): 193–265. doi:10.1098/rstb.1932.0016.
^McLoughlin, Stephen; Carpenter, Raymond J.; Jordan, Gregory J.; Hill, Robert S. (2008). "Seed ferns survived the end-Cretaceous mass extinction in Tasmania". American Journal of Botany. 95 (4): 465–471. doi:10.3732/ajb.95.4.465. ISSN 1537-2197. PMID 21632371.
corystospermaceae, corystosperms, group, extinct, seed, plants, belonging, family, assigned, order, corystospermales, umkomasiales, they, were, first, described, based, fossils, collected, hamshaw, thomas, from, burnera, waterfall, locality, near, umkomaas, ri. Corystosperms are a group of extinct seed plants belonging to the family Corystospermaceae assigned to the order Corystospermales 2 or Umkomasiales 3 They were first described based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa 4 Corystosperms are typified by a group of plants that bore Dicroidium leaves Umkomasia ovulate structures and Pteruchus pollen organs that were widespread over Gondwana during the Middle and Late Triassic Other fossil Mesozoic seed plants with similar reproductive structures have also sometimes been included within the corystosperm concept sensu lato such as the doyleoids from the Early Cretaceous of North America and Asia 3 A potential corystosperm the leaf fossil Komlopteris cenozoicus is known from the Eocene of Tasmania at least 13 million years after the Cretaceous Paleogene extinction event 5 CorystospermaceaeTemporal range Late Permian Early Jurassic PreꞒ Ꞓ O S D C P T J K Pg NUmkomasia macleanii reconstructed plant Late Triassic Molteno Formation Umkomaas South Africa Including Dicroidium leaves D Umkomasia ovulate organ L P and Pteruchus pollen organ H K 1 Scientific classificationKingdom PlantaeOrder CorystospermalesFamily CorystospermaceaeThomas 1933GeneraUmkomasia ovulate structures Pteruchus pollen organs Dicroidium leaves Johnstonia leaves Xylopteris leaves Kyklyxylon wood Antarcticoxylon wood Rhexoxylon wood Doyleoids sometimes included Doylea ovulate structures Jarudia ovulate structures Tevshiingovia ovulate structures Umkomasia macleanii ovulate structure from the Late Triassic Molteno Formation of Umkomaas South Africa Contents 1 Description 2 See also 3 References 4 External linksDescription EditUmkomasiaceae have helmet like cupules around ovules born in complex large branching structures Umkomasia The pollen organ Pteruchus has numerous cigar shaped pollen sacs hanging from epaulette like blades again in complex branching structures Pteruchus africanus pollen structure from the Late Triassic Molteno Formation of Umkomaas South Africa The leaves Dicroidium are tied to the fertile organs by similarities of cuticular structure because their cuticles were robust like those of gymnosperms and unlike the thin leaves of ferns Dicroidium odontopteroides leaf from the Late Triassic Molteno Formation of Birds River South AfricaSee also EditEvolution of plantsReferences Edit Retallack G J Dilcher D L 1988 Reconstructions of selected seed ferns Missouri Botanical Garden Annals 75 3 1010 1057 doi 10 2307 2399379 JSTOR 2399379 Abu Hamad A Blomenkemper P Kerp H Bomfleur B December 2017 Dicroidium bandelii sp nov corystospermalean foliage from the Permian of Jordan PalZ 91 4 641 648 doi 10 1007 s12542 017 0384 2 ISSN 0031 0220 a b Shi Gongle Herrera Fabiany Herendeen Patrick S Clark Elizabeth G Crane Peter R 2022 12 31 Silicified cupulate seed bearing structures from the Early Cretaceous of eastern Inner Mongolia China rethinking the corystosperm concept Journal of Systematic Palaeontology 20 1 1 33 doi 10 1080 14772019 2022 2133644 ISSN 1477 2019 S2CID 253562726 Thomas H H 1933 On some pteridospermous plants from the Mesozoic rocks of South Africa Philosophical Transactions of the Royal Society B 222 483 493 193 265 doi 10 1098 rstb 1932 0016 McLoughlin Stephen Carpenter Raymond J Jordan Gregory J Hill Robert S 2008 Seed ferns survived the end Cretaceous mass extinction in Tasmania American Journal of Botany 95 4 465 471 doi 10 3732 ajb 95 4 465 ISSN 1537 2197 PMID 21632371 External links Edit Fossilworks Lepidopteris paleodb org Retrieved 2016 03 18 Retrieved from https en wikipedia org w index php title Corystospermaceae amp oldid 1147019155, wikipedia, wiki, book, books, library,
