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37. First Cenozoic Macrofossil Record of Polypodiaceae from India and Its Biogeographic Implications.

Author

Kundu, Sampa, Hazra, Taposhi, Chakraborty, Tapan, Bera, Subir, Taral, Suchana, and Khan, Mahasin Ali

Subjects
CENOZOIC Era, FERNS, FOSSILS, MIOCENE Epoch, EDIACARAN fossils, FOSSIL plants
Abstract

Premise of research. Polypodiaceae, the largest leptosporangiate fern family, is distributed mainly in the tropical and subtropical regions of India, China, New Zealand, and Malaysia. This family has a rich macrofossil record in the Cenozoic sediments of China, but no macrofossil of Polypodiaceae has been reported from the Cenozoic sediments of India to date. Here, we report for the first time the occurrence of fossil frond remains resembling morphologically those of the extant microsoroid wart fern genus Microsorum Link from the late Miocene Siwalik sediments exposed around Sarkaghat, Mandi district of Himachal Pradesh, Western Himalaya, India. Methodology. The present frond fossils were revealed by careful removal of the overlying matrix and studied under light compound, stereo zoom, and inverted fluorescence microscopes. They are identified based on their detailed morphological (macro and micro) features and through the comparison with other modern Polypodiaceae genera as well as with earlier reported polypodiceous fern fossil species. Pivotal results. The fossil frond specimens are described here as a new species, namely, Palaeosorum siwalikum Kundu, Hazra et Khan sp. nov. The new Siwalik vascular cryptogam species is characterized by leaf shape (simple frond with entire margin), venation pattern (brochidodromous nature of secondary veins, tertiary and quaternary veins reticulate, anastomosing and forming a row of irregular or quadrangular-shaped areoles between two lateral secondary veins), and presence of free included veinlets (unbranched or forked, ending with club-shaped hydathodes). Conclusions. These new fossil materials confirm the existence of a Microsorum -like plant in the Siwalik Miocene forests of Himachal Pradesh. We review in detail the fossil record and highlight the phytogeographic history of Polypodiaceae. In addition, we also suggest probable migratory routes for this fern family. [ABSTRACT FROM AUTHOR]

Published
2024
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48. First fossil evidence of samaras of Ventilago Gaertn. (Rhamnaceae) from India and its implications.

Author

Hazra, Taposhi, Kundu, Sampa, Bera, Subir, Chakraborty, Tapan, and Khan, Mahasin Ali

Subjects
FOSSILS, COMMUNITY forests, NEOGENE Period, MIOCENE Epoch, PLIOCENE Epoch, VEINS
Abstract

The Ventilago Gaertn. (Rhamnaceae) is widely distributed in pantropical areas of Africa, Asia, and Australia. However, fossil records of this taxon are sparse, which limits understanding of the evolution and biogeographic history of the genus. In the present study, we report and describe two new fossil species of Ventilago, V. siwalika sp. nov. from the Miocene sediments of Himachal Pradesh, western Himalaya, and V. pliocenica sp. nov. from the Pliocene sediments of Jharkhand, eastern India based on single‐winged samaras. Ventilago pliocenica is characterized by a prominent midvein, obtuse to sub‐round apex with mucronate tip, longitudinal secondary veins extending the full length of the fruit, and reticulate nature of higher‐order veins, the presence of equatorial rim, the hypanthium, and short pedicel. On the other hand, V. siwalika is characterized by a prominent midvein, obtuse to sub‐round apex with mucronate tip, longitudinal secondary veins extending the full length of the fruit, and reticulate nature of higher‐order veins. Our discovery represents the first unambiguous fossil record of single‐winged samara of Ventilago from India and provides valuable insights into the evolution of this genus. In this paper, we also review its biogeographic history and add new information to understand its hypothetical migration route. Present and earlier records of Ventilago also suggest that this genus was a common forest element during Neogene (Miocene time) in Asia. [ABSTRACT FROM AUTHOR]

Published
2023
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