First record of Chelonian coprolites from the Early-Middle Miocene Kutch Basin, western India, and their palaeodietary and palaeobiological implications

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Geobios Pub Date : 2024-06-01 DOI:10.1016/j.geobios.2023.12.004

Ramanand Sagar , Vivesh V. Kapur , Kamlesh Kumar , P. Morthekai , Anupam Sharma , Sunil K. Shukla , Amit K. Ghosh , Gaurav Chauhan , M.G. Thakkar

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Abstract

In this paper, we provide the first data on large (cm-sized) coprolites (represented by three morphotypes) comprising a rare occurrence of eight specimens from a total of three vertebrate-bearing horizons identified within the Early Miocene (Aquitanian) Khari Nadi Formation and Middle Miocene (Burdigalian-Langhian) Chassra Formation, Kutch Basin, western India. The geochemical data confirm the phosphatic character of the investigated ichnofossils. The dominance of partly digested bone matter and presence of plant remains in all the three coprolite morphotypes reflects the omnivorous diet of the producers, which were most likely chelonians. The occurrence of an inclusion (in a coprolite specimen recorded in this study) showcasing an ultrastructure similar to mammalian dental enamel is a rarity in Neogene coprolite records. Additional biotic inclusions observed in the investigated coprolites include ostracods (assigned to genera Paractinocythereis, Hermanites, and Propontocypris); large planispiral benthic foraminifera including the genus Quinqueloculina; uniserial and biserial benthic foraminifera belonging to genus Textularia; marine calcareous algae genus Actinoporella; chrysophytes (resting spores or cysts of planktonic algae); sponge spicules (represented by the morphotypes Acanthoxea and Strongyle); freshwater diatom genus Aulacoseira; unidentified fungal remains; and phytoliths. Taken together, the biotic and abiotic (e.g., pyrite) inclusions, geochemical data and associated microbiota suggest that these ichnofossils were deposited in a dominantly coastal marine (intertidal) setting linked to a lacustrine/palustrine environment.

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印度西部中新世早中期卡奇盆地首次发现的螯足类共生石及其古饮食和古生物学意义

本文首次提供了印度西部卡奇盆地早中新世（阿奎坦统）Khari Nadi 地层和中中新世（布迪加里-朗格安统）Chassra 地层中发现的大型（厘米大小）桡足化石（由三种形态代表）的数据，这些桡足化石由罕见的共三个含脊椎动物的地层中的八个标本组成。地球化学数据证实了所调查的化石具有磷酸盐特征。在所有三种桡骨化石形态类型中，部分消化的骨质和植物残骸占主导地位，这反映了生产者的杂食性，很可能是螯龙类。在本研究记录的桡足石标本中，出现了与哺乳动物牙釉质超微结构相似的包裹体，这在新近纪桡足石记录中十分罕见。在所调查的共生石中观察到的其他生物内含物包括：鸵鸟类（归属于 Paractinocythereis 属、Hermanites 属和 Propontocypris 属）；包括 Quinqueloculina 属在内的大型平面螺旋底栖有孔虫；属于 Textularia 属的单列和双列底栖有孔虫；海洋钙质藻类 Actinoporella 属；菊石类（浮游藻类的静止孢子或囊胞）；海绵刺丝（以 Acanthoxea 和 Strongyle 形态为代表）；淡水硅藻 Aulacoseira 属；不明真菌残骸；以及植物石。综合来看，生物和非生物（如黄铁矿）包裹体、地球化学数据和相关微生物群表明，这些化石主要沉积在与湖泊/河口环境相连的沿海海洋（潮间带）环境中。

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来源期刊

Geobios 地学-古生物学

CiteScore

3.30

自引率

6.20%

发文量

审稿时长

6-12 weeks

期刊介绍： Geobios publishes bimonthly in English original peer-reviewed articles of international interest in any area of paleontology, paleobiology, paleoecology, paleobiogeography, (bio)stratigraphy and biogeochemistry. All taxonomic groups are treated, including microfossils, invertebrates, plants, vertebrates and ichnofossils. Geobios welcomes descriptive papers based on original material (e.g. large Systematic Paleontology works), as well as more analytically and/or methodologically oriented papers, provided they offer strong and significant biochronological/biostratigraphical, paleobiogeographical, paleobiological and/or phylogenetic new insights and perspectices. A high priority level is given to synchronic and/or diachronic studies based on multi- or inter-disciplinary approaches mixing various fields of Earth and Life Sciences. Works based on extant data are also considered, provided they offer significant insights into geological-time studies.