Holigarna (Anacardiaceae) from the early Eocene of Western India and its palaeogeographical and palaeoclimatological significance

Thick lignite deposits on the western margin of India were preserved on account of thick vegetation which got buried underneath due to tectonic activities that occurred in northwestern part of India during the early Palaeogene. Study of the fossil flora preserved in these beds is important to deduce...

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Bibliographic Details
Published in:Journal of the Geological Society of India 2016-05, Vol.87 (5), p.520-524
Main Authors: Shukla, Anumeha, Mehrotra, Rakesh Chandra
Format: Article
Language:English
Subjects:
Affinity
Boundaries
Earth and Environmental Science
Earth Sciences
Eocene
Equatorial regions
Flora
Fossils
Geology
Hydrogeology
Lignite
Mines
Oil shale
Paleocene
Paleoclimate
Paleoclimate science
Phylogenetics
Plant fossils
Plants (organisms)
Rain forests
Rainforests
Vegetation
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Summary:Thick lignite deposits on the western margin of India were preserved on account of thick vegetation which got buried underneath due to tectonic activities that occurred in northwestern part of India during the early Palaeogene. Study of the fossil flora preserved in these beds is important to deduce the palaeoclimate of the region. Therefore, a field work was undertaken to collect plant fossils from the Tarkeshwar lignite mine, Surat district, Gujarat (western India) which is still unexplored as far as the plant mega-remains are concerned. A fossil wood is systematically described from the Cambay Shale Formation of the mine considered to be of early Eocene in age. It shows close affinities with Holigarna (Anacardiaceae), particularly with H. beddomei and H. grahamii . This genus is evergreen in nature and grows in the Indo-Malayan region, while both the modern analogues of the fossil are endemic to semi-evergreen to evergreen forests ofWestern Ghats, south India, located at the equator. This not only confirms the palaeolatitudinal position of the Indian subcontinent at the equator during the early Palaeogene, but also indicates the presence of equatorial rain forest in the Indian subcontinent during the period. Based on the timetree, Sapindales started to diverge in the early Palaeocene (62–57 Ma) as its oldest fossil is from the K-Pg boundary. Discovery of the present anacardiaceous fossil (belonging to Sapindales) from the early Eocene strengthens the above phylogenetic view.
ISSN:0016-7622
0974-6889
DOI:10.1007/s12594-016-0425-6