A well preserved miogypsinids and lepidocyclinids assemblage collected from the fossiliferous Quilon Beds in SW India (Padappakkara locality) is here illustrated and discussed. This assemblage is composed by two species of miogypsinids (Miogypsina globulina and Lepidosemicyclina thecideaeformis) and two species of lepidocyclinids (Nephrolepidina chavarana and Nephrolepidina sumatrensis). Forty-one specimens of miogypsinids have been investigated by computed tomography: this allowed the measurements of a number of biometric parameters obtained on equatorial and axial sections of the specimens as well as abundant information on the ontogenetic changes of the chamber morphology which is of pivotal importance to differentiate the genera Miogypsina from Lepidosemicyclina. Especially for primitive stages of Lepidosemicyclina, the differentiation between these two genera can be rather difficult but the CT scans here obtained help in making a clear separation. Additionally, the complete test geometry in both equatorial and axial sections is displayed for agamonts of both miogypsinids, which are very rare for the Indian taxa. The results from this work point to a clear Burdigalian assemblage with some biometric characteristics such as the reduction of the proloculus size which is relatively common evidence in all Indo-Pacific miogypsinids fauna so far investigated.

The Miocene (Burdigalian) lepidocyclinids and miogypsinids of Channa Kodi, Padappakkara, Kerala, Southern India

antonino briguglio
2018

Abstract

A well preserved miogypsinids and lepidocyclinids assemblage collected from the fossiliferous Quilon Beds in SW India (Padappakkara locality) is here illustrated and discussed. This assemblage is composed by two species of miogypsinids (Miogypsina globulina and Lepidosemicyclina thecideaeformis) and two species of lepidocyclinids (Nephrolepidina chavarana and Nephrolepidina sumatrensis). Forty-one specimens of miogypsinids have been investigated by computed tomography: this allowed the measurements of a number of biometric parameters obtained on equatorial and axial sections of the specimens as well as abundant information on the ontogenetic changes of the chamber morphology which is of pivotal importance to differentiate the genera Miogypsina from Lepidosemicyclina. Especially for primitive stages of Lepidosemicyclina, the differentiation between these two genera can be rather difficult but the CT scans here obtained help in making a clear separation. Additionally, the complete test geometry in both equatorial and axial sections is displayed for agamonts of both miogypsinids, which are very rare for the Indian taxa. The results from this work point to a clear Burdigalian assemblage with some biometric characteristics such as the reduction of the proloculus size which is relatively common evidence in all Indo-Pacific miogypsinids fauna so far investigated.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/927829
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