Thecamoebians from Late Permian Gondwana sediments of peninsular India

The evolutionary history of thecamoebians (testate amoebae) extends back to the Neoproterozoic Era. However, until now, these have had a restricted, discontinuous and modest record across the world. The studied sediment of Raniganj Formation (Godavari Graben), Andhra Pradesh, India has been assigned...

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Bibliographic Details
Published in:European journal of protistology 2014-02, Vol.50 (1), p.89-105
Main Authors: Farooqui, Anjum, Aggarwal, Neha, Jha, Neerja
Format: Article
Language:English
Subjects:
Amoebozoa - classification
Amoebozoa - cytology
Arcellidae
Biodiversity
Biological and medical sciences
Biological evolution
Centropyxidae
Centropyxis aerophila
Difflugiidae
Earth sciences
Earth, ocean, space
Exact sciences and technology
Fossils
Fundamental and applied biological sciences. Psychology
Genetics of eukaryotes. Biological and molecular evolution
Gondwana
India
Late Permian
Morphostasis
Paleontology
Paleontology: general
Plagiopyxidae
Raniganj Formation
Thecamoebians
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Summary:The evolutionary history of thecamoebians (testate amoebae) extends back to the Neoproterozoic Era. However, until now, these have had a restricted, discontinuous and modest record across the world. The studied sediment of Raniganj Formation (Godavari Graben), Andhra Pradesh, India has been assigned as Late Permian on the basis of co-occurring age-diagnostic Late Permian palynomorphs. About sixteen thecamoebian species and one taxon incertae sedis have been recorded here in the palynological slides on the basis of shell morphology and morphometry. Out of these, five belong to the family Arcellidae, seven to Centropyxidae, two to Trigonopyxidae, one to Difflugiidae, one to Plagiopyxidae, and one is regarded incertae sedis. The morphometric characteristics of fossil forms resemble their corresponding extant species studied from ecologically diverse fresh water wetlands in India. In general, the ratio of shell diameter and aperture diameter of Late Permian fossil and extant specimens show significant correlation in all the studied species. Except that, the ratio of shell length and breadth is the distinguishing feature between Centropyxis aerophila and C. aerophila ‘sylvatica’, rather than the ratio of shell length and longest diameter of the shell aperture in both fossil and extant forms. The study elucidates the minimal morphological evolution in thecamoebians and their survival during mass extinction periods and stressful environmental conditions over the geological timescale.
ISSN:0932-4739
1618-0429
DOI:10.1016/j.ejop.2013.05.003