The Malvaceae first appeared in the Cretaceous in North America, and have achieved a global distribution today, most notably as a significant component of almost all tropical forests. The genus Florissantia shows a number of features associated with different extant subfamilies of the Malvaceae, and is known from the Middle Eocene till the Miocene of western North America, with specimens known from British Colombia, Colorado, Montana, Oregon, and Washington, as well as a single specimen being known from the Sikhote Alin mountains of the Russian Far East.
In a paper published in the journal Botany Letters on 21 October 2024, Ashif Ali and Mahasin Ali Khan of the Palaeobotany, Palynology, and Plant Evolution Laboratory at Sidho-Kanho-Birsha University, and Raman Patel and Rajendra Singh Rana of the Department of Geology at Rauthan Hemvati Nandan Bahuguna Garhwal University, describe a specimen of Florissantia from the Early Eocene Palana Formation of Rajasthan, India.
The specimen comes from the Laminate Maroon Shale Bed of the Palana Formation, which is exposed at the Gurha Open-cast Lignite Mine at Bikaner in northwest Rajasthan. It is preserved as part and counterpart on a piece of a piece of split- laminated shale, which has been further exposed by micro excavation of successive layers of the rock with fine needles under a dissection microscope.
The preserved fossil is a star-shaped flower about 13 mm in diameter (sgnificantly smaller than any other member of the genus), with a calyx made up of five fused and rounded sepals of roughly equal length; the petals are missing. Importantly, the sepals each show numerous prominent veins, the pattern of which is used by Ali et al. as a diagnostic tool to place the specimen in the genus Florissantia.
The Palana Formation of Rajasthan has been dated to between about 55 and 52 million years before the present on the basis of palynological data (fossil pollen). This Early Eocene date makes the Bikanar specimen the oldest representative of the genus Florissantia, which together with its unexpected location, potentially makes the specimen highly significant.
The Palana Formation was laid down on the shores of an ancient lake, which is consistent with other locations where members of the genus Florissantia have been found. Other members of the genus are known from lake-associated Floras in tropical, subtropical, and temperate environments, often with some volcanic input; although the presence of volcanic ashes helps to preserve fine structures such as flowers, so it is possible that this connection with volcanic input reflects preservation bias rather than an environmental preference of the living plants.
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