Early Eocene equatorial vegetation and depositional environment: Biomarker and palynological evidences from a lignite-bearing sequence of Cambay Basin, western India

Sabatier, Paul; Sharma, Jyoti; Singh, Bhagwan D.; Saraswati, Pratul Kumar; Dutta, Suryendu

doi:10.1016/j.coal.2015.06.017

Cited by 39 publications

(7 citation statements)

References 46 publications

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“…Nowadays, SE Asia is recognized as having one of the world's most complex and least understood geological histories (Sun & al., 2000). In the Early Palaeogene, the Indian subcontinent witnessed enormous floral diversification as a result of a global rise in temperature and changes in latitudinal position (Zachos & al., 2001; Rana & al., 2004; Sahni & al., 2006; Garg & al., 2008; Shukla & al., 2013; Paul & al., 2015). Modern‐type, broad‐leaf tropical Dipterocarpaceae forests were spread across the Indian subcontinent from the Eocene (52 Ma) (Van Aarssen & al., 1994; Anderson & Muntean, 2000; Dutta & al., 2009; Mallick & al., 2009; Rust & al., 2010; Rudra & al., 2014; Paul & al., 2015).…”

Section: Discussionmentioning

confidence: 99%

“…In the Early Palaeogene, the Indian subcontinent witnessed enormous floral diversification as a result of a global rise in temperature and changes in latitudinal position (Zachos & al., 2001; Rana & al., 2004; Sahni & al., 2006; Garg & al., 2008; Shukla & al., 2013; Paul & al., 2015). Modern‐type, broad‐leaf tropical Dipterocarpaceae forests were spread across the Indian subcontinent from the Eocene (52 Ma) (Van Aarssen & al., 1994; Anderson & Muntean, 2000; Dutta & al., 2009; Mallick & al., 2009; Rust & al., 2010; Rudra & al., 2014; Paul & al., 2015). Our results suggest an early Eocene diversification for Dipterocarpoideae (51.78 Ma), and the origin of all its main tribes during the Middle Eocene (ca.…”

Section: Discussionmentioning

confidence: 99%

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Phylogenomics and a revised tribal classification of subfamily Dipterocarpoideae (Dipterocarpaceae)

Cvetković

Hinsinger

Thomas

et al. 2022

TAXON

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Dipterocarpoideae, the largest subfamily in the Meranti family (Dipterocarpaceae) are an ecologically dominant group of trees throughout much of wet tropical Asia. Increasing anthropogenic pressures on this economically important tree family make it essential to resolve their complex evolutionary relationships and understand the distribution of genetic diversity throughout the family and distribution range. Dipterocarpaceae have been the focal group in a wide range of studies, owing to their economic value, importance in historical biogeography and key role in the evolution of the Asian tropical forest biome. Despite this, persistent taxonomic and evolutionary questions remain, ranging from questions on the geographic origin, sequence of dispersal and the identification of diagnostic characters to circumscribe proper evolutionary groups. Here we present a comprehensive phylogenomic hypothesis for Dipterocarpoideae, based on the analyses of plastome and nuclear cistron (NRC) data, and provide an in‐depth review on the validity of morphological characters underlying the new tribal classification proposed here for the subfamily. Phylogenomic relationships were inferred using maximum likelihood and Bayesian approaches. Estimates of origin and onset of diversification in major clades and lineages were reconstructed using plastome, nuclear and combined datasets. Results of the separate and combined genomic datasets partly corroborate elements of previous classification systems (with improved support at all levels for major clades) but provide strong support for revising the tribal classification of the subfamily into four main clades: Dipterocarpeae (Dipterocarpus), Dryobalanopseae (Dryobalanops), Shoreeae (Hopea, Neobalanocarpus, Parashorea, and all parts of a polyphyletic Shorea) and Vaterieae (including all other presently accepted Dipterocarpoideae genera). Multi‐fossil‐dated divergence time estimation suggests Vaterieae first originated in the Late Cretaceous, followed by Dipterocarpeae, with subsequent rise of the Dryobalanopseae and Shoreeae in the Eocene. Diversification of all tribes commenced before the Early Miocene. Our results provide strong support for the position of Neobalanocarpus heimii, Parashorea and (sub‐)sections of the genera Anisoptera, Hopea, Shorea and Vatica. Hypotheses on the origin of Neobalanocarpus heimii by intergeneric hybridisation between Anthoshorea (maternally inherited) and Hopea (paternally inherited) species were corroborated. Finally, our study provides support for future revisionary changes: (1) the elevation to generic rank of sections in Shorea; and (2) revising the infrageneric classification of Hopea as all (sub‐)sections were recovered as not monophyletic.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Phylogenomics and a revised tribal classification of subfamily Dipterocarpoideae (Dipterocarpaceae)

Cvetković

Hinsinger

Thomas

et al. 2022

TAXON

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“…Podocarpus is the only representative among gymnosperms. Late Paleocene and early Eocene sediments contain the oldest pollen and geochemical fossils attributable to the family Dipterocarpaceae (Dutta et al 2011, Paul et al 2015). Remarkably, the insect fauna from early Eocene amber contains many elements characteristic of present-day South-East Asian dipterocarp forests (Rust et al 2010).…”

Section: The Collision Of India With Asia and Eocene Diversification mentioning

confidence: 99%

Assembly and division of the South and South-East Asian flora in relation to tectonics and climate change

2018

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Abstract:The main phases of plant dispersal into, and out of the South-East Asian region are discussed in relation to plate tectonics and changing climates. The South-East Asian area was a backwater of angiosperm evolution until the collision of the Indian Plate with Asia during the early Cenozoic. The Late Cretaceous remains poorly understood, but the Paleocene topography was mountainous, and the climate was probably seasonally dry, with the result that frost-tolerant conifers were common in upland areas and a low-diversity East Asian aspect flora occurred at low altitudes. India's drift into the perhumid low latitudes during the Eocene brought opportunities for the dispersal into South-East Asia of diverse groups of megathermal angiosperms which originated in West Gondwana. They successfully dispersed and became established across the South-East Asian region, initially carried by wind or birds, beginning at about 49 Ma, and with a terrestrial connection after about 41 Ma. Many Paleocene lineages probably went extinct, but a few dispersed in the opposite direction into India. The Oligocene was a time of seasonally dry climates except along the eastern and southern seaboard of Sundaland, but with the collision of the Australian Plate with Sunda at the end of the Oligocene widespread perhumid conditions became established across the region. The uplift of the Himalaya, coinciding with the middle Miocene thermal maximum, created opportunities for South-East Asian evergreen taxa to disperse into north India, and then with the late Miocene strengthening of the Indian monsoon, seasonally dry conditions expanded across India and Indochina, resulting eventually in the disappearance of closed forest over much of the Indian peninsula. This drying affected Sunda, but it is thought unlikely that a ‘savanna’ corridor was present across Sunda during the Pleistocene. Some dispersals from Australasia occurred following its collision with Sunda and following the uplift of New Guinea and the islands of Wallacea, Gondwanan montane taxa also found their way into the region. Phases of uplift across the Sunda region created opportunities for allopatric speciation and further dispersal opportunities. There is abundant evidence to suggest that the Pleistocene refuge theory applies to the South-East Asian region.

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“…The palynological analyses carried out in all the Eocene lignite bearing successions of western India including the Kutch and Cambay basins of Gujarat, and the Barmer Basin of Rajasthan exhibit a prevalence of tropical C3 plant types, such as palm, dipterocarps etc. (e.g., Mathews et al, 2018;Paul et al, 2015;Sahay, 2011). Singh (2021) recently reported a similar palynological assemblage from the Umarsar mine.…”

Section: Isotope Stratigraphy and Hyperthermal Events δ 13 C Orgmentioning

confidence: 91%

“…The recent geological investigations of these mine sections yielded well-preserved fossils of vertebrates, and insects preserved in amber associated with the lignite seams (Bajpai et al, 2005;Folie et al, 2012;Kumar et al, 2007;Rana et al, 2013;Rose et al, 2009;Rust et al, 2010). Besides, time-diagnostic microfossils, foraminifers and palynomorphs, have also been reported from these mines (Agrawal et al, 2017;Garg et al, 2008;Paul et al, 2015;Rao et al, 2013;Singh, 2021). These fossils and a few isotopic analyses unambiguously indicate a Ypresian (early Eocene) age of the lignitic succession found from most of these mines (e.g., Khozyem et al, 2021;Punekar & Saraswati, 2010;Samanta et al, 2013).…”

Section: Introductionmentioning

confidence: 94%

A study on benthic molluscs and stable isotopes from Kutch, western India reveals early Eocene hyperthermals and pronounced transgression during ETM2 and H2 events

2022

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The early Eocene greenhouse Earth experienced several transient global warming events, indicated by sharp negative excursions in the stable isotope ratios of carbon and oxygen. A huge amount of CO2, enriched with 12C, was released in the ocean–atmosphere system leading to warming. The Paleocene–Eocene boundary is demarcated by the most significant and well-known hyperthermal event, Paleocene–Eocene thermal maximum (PETM). The PETM is documented to be accompanied by a transgression. The later hyperthermals are relatively less studied. Information on the hyperthermals from the palaeo-tropical basins are relatively few. Here, we present a high-resolution litho-, bio- and isotope–stratigraphic analysis of the early Eocene succession from the Kutch Basin, western India. Stable isotopes of carbon and oxygen were analysed from sediments (δ13Corg) and mollusc shells (δ13Ccarb and δ18Ocarb). The succession, prevailingly with lignite, along with carbonaceous black shale and plenty of fossil plant remains, is primarily a product of terrestrial environment. A pronounced marine transgression, characterised by marine mollusc bearing glauconitic shale in the middle of the succession, indicates a coastal transitional setting between the ocean and land. The δ13C curve of organic carbon reveals five negative excursions, which are identified as the PETM, Eocene thermal maximum 2 (ETM2)/H1, H2, I1 and I2 in ascending order. The hyperthermal pair of ETM2–H2 corresponds with the marine interval. δ13Ccarb and δ18Ocarb from the middle part of the succession reveal concomitant negative excursions. The association between these hyperthermals and transgression appears to be regionally and globally valid, which strongly suggests a causal link between them.

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Early Eocene equatorial vegetation and depositional environment: Biomarker and palynological evidences from a lignite-bearing sequence of Cambay Basin, western India

Cited by 39 publications

References 46 publications

Phylogenomics and a revised tribal classification of subfamily Dipterocarpoideae (Dipterocarpaceae)

Phylogenomics and a revised tribal classification of subfamily Dipterocarpoideae (Dipterocarpaceae)

Assembly and division of the South and South-East Asian flora in relation to tectonics and climate change

A study on benthic molluscs and stable isotopes from Kutch, western India reveals early Eocene hyperthermals and pronounced transgression during ETM2 and H2 events

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