Morphology, biostratigraphy, and evolution of Pliocene-Pleistocene diatoms Proboscia barboi and Proboscia curvirostris
Andrade, João (Universidade Nova de Lisboa. Departamento de Ciências da Terra)
Legoinha, Paulo (Universidade Nova de Lisboa. Geobiotec)
Stroynowski, Zuzia (Instituto Português do Mar e da Atmosfera (Algés, Portugal))
Abrantes, Fátima (Centro de Ciências do Mar do Algarve (Faro, Portugal))

Date:	2019
Abstract:	Proboscia barboi and Proboscia curvirostris are two important diatom biostratigraphic markers from the high latitudes of the North Pacific and North Atlantic Oceans, dating back to the Pliocene-Pleistocene time. This study analyzes the biostratigraphic events and describes the morphology of P. barboi and P. curvirostris, particularly the morphologic variations of the latter species, based on observations of samples of Core U1340A from the IODP Expedition 323 in the Bering Sea. In Site U1340, the First Occurrence of P. curvirostris is observed at 1. 52Ma and its First Common Occurrence at 1. 39Ma, where morphologic variations were found abundantly. The Last Occurrence of P. curvirostris was found at 0. 33Ma, while P. barboi's Last Occurrence is found at 0. 67Ma. Based on the morphological similarity and known biostratigraphic distribution, previous authors have assumed that P. curvirostris descends from P. barboi, although this hypothesis is still in debate. At 1. 39Ma P. curvirostris shows an increased size and thickness, which is typical of P. barboi, and some specimens display an incipient structure characteristic of P. curvirostris - the secondary spine. This morphology is intermediate between the two species and suggests an evolutionary transition from P. barboi to P. curvirostris. However, P. curvirostris already existed since 1. 9Ma in the subarctic indicating that its speciation happened much earlier than 1. 39Ma. Furthermore, since P. barboi co-occurs with P. curvirostris in the North Pacific, this evolutionary process was cladogenetic. Besides being evidence for a phylogenetic relationship, the abundant occurrence of intermediate forms at 1. 39Ma may constitute a bioevent for a short time interval in the Bering Sea.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Probosciaceae ; Proboscis ; Longitudinal ridges ; Site U1340 ; Quaternary
Published in:	Geologica acta, Vol. 17 (2019) , p. 1-17, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/361041
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/GeologicaActa2019.17.9
DOI: 10.1344/GeologicaActa2019.17.9

17 p, 15.2 MB

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