Revision of the fossil flower genus Sahnianthus Shukla (Myrtales) from the latest Cretaceous Deccan Intertrappean Beds of India

Interbeds of the Deccan traps, ~66 million years old, have long been known to contain cherts with anatomically preserved flowers, fruits and seeds. We studied numerous specimens of Sahnianthus , the iconic flower of Deccan Intertrappean cherts, by micro-CT scanning, as well as traditional cellulose...

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Bibliographic Details
Main Authors: Ashley M. Hamersma, Chandana Karumanchi, Dashrath K. Kapgate, Kathleen B. Pigg, Selena Y. Smith, Shirley A. Graham, Steven R. Manchester
Format: Article
Language:English
Published: W. Szafer Institute of Botany, Polish Academy of Sciences 2025-06-01
Series:Acta Palaeobotanica
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Online Access:https://acpa.botany.pl/Revision-of-the-fossil-flower-genus-Sahnianthus-Shukla-Myrtales-from-the-latest-Cretaceous,202410,0,2.html
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Summary:Interbeds of the Deccan traps, ~66 million years old, have long been known to contain cherts with anatomically preserved flowers, fruits and seeds. We studied numerous specimens of Sahnianthus , the iconic flower of Deccan Intertrappean cherts, by micro-CT scanning, as well as traditional cellulose acetate peels and scanning electron microscopy of the in-situ pollen, to reconstruct the original floral and pollen morphology. The flowers were collected, in association with fruits of Enigmocarpon , from the type locality of Mohgaon Kalan in Chhindwara, Pradesh and other locations in Madhya Pradesh and Maharashtra, Central India. Using micro- CT scans to vary the orientation of virtual sections of complete flowers embedded in chert, we show that nine additional, previously described fossil flower genera represent the same plant and are thus synonyms of Sahnianthus . In addition, we suggest that much of the variation observed in the specimens is due to preservation at different developmental stages from bud to maturity. We observed that the epiphyllous stamens are borne in two whorls contrary to prior treatments assuming a single whorl. The number of stamens in each whorl ranges from seven to nine and is equivalent to the number of perianth lobes and ovary locules of the same flower. The pollen is spheroidal and psilate with inconspicuous narrow colpi and a prominent rib-like equatorial thickening of the exine; these features facilitate recognizing the identity of flowers previously assigned to other genera. The combined characters of Sahnianthus, together with fruit and seed characters of Enigmocarpon , are consistent with placement within, or close to, Lythraceae, as previously suggested.
ISSN:2082-0259