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A dwarf walrus from the Miocene of Baja California Sur, Mexico

Here, we describe the odobenid Nanodobenus arandai gen. et sp. nov., based on a nearly complete left mandible from the mid to late Miocene Tortugas Formation in Baja California Sur. Nanodobenus is distinguished among odobenids by displaying a unique combination of plesiomorphic and derived character...

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Autores principales: Velez-Juarbe, Jorge, Salinas-Márquez, Fernando M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society Publishing 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6124023/
https://www.ncbi.nlm.nih.gov/pubmed/30225030
http://dx.doi.org/10.1098/rsos.180423
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author Velez-Juarbe, Jorge
Salinas-Márquez, Fernando M.
author_facet Velez-Juarbe, Jorge
Salinas-Márquez, Fernando M.
author_sort Velez-Juarbe, Jorge
collection PubMed
description Here, we describe the odobenid Nanodobenus arandai gen. et sp. nov., based on a nearly complete left mandible from the mid to late Miocene Tortugas Formation in Baja California Sur. Nanodobenus is distinguished among odobenids by displaying a unique combination of plesiomorphic and derived characters, such as narrow mandibular symphysis, well-developed genial tuberosity, bilobed canine and p2 roots, bulbous post-canine teeth with the paraconid, protoconid and hypoconid, and smooth lingual cingula. Moreover, it is characterized by its small adult body length, which is estimated at about 1.65 m. Throughout the Miocene–Pliocene odobenids are characterized by an increase in body size, especially after the extinction of desmatophocids in the late Miocene. The small size of Nanodobenus departs from this trend, demonstrating that there was greater size disparity among odobenids in the mid–late Miocene than previously thought. It is hypothesized that Nanodobenus occupied a niche that was later on occupied by similar-sized otariids, such as Thalassoleon mexicanus, which occurs sympatrically with large odobenids in the overlying Almejas Formation.
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spelling pubmed-61240232018-09-17 A dwarf walrus from the Miocene of Baja California Sur, Mexico Velez-Juarbe, Jorge Salinas-Márquez, Fernando M. R Soc Open Sci Biology (Whole Organism) Here, we describe the odobenid Nanodobenus arandai gen. et sp. nov., based on a nearly complete left mandible from the mid to late Miocene Tortugas Formation in Baja California Sur. Nanodobenus is distinguished among odobenids by displaying a unique combination of plesiomorphic and derived characters, such as narrow mandibular symphysis, well-developed genial tuberosity, bilobed canine and p2 roots, bulbous post-canine teeth with the paraconid, protoconid and hypoconid, and smooth lingual cingula. Moreover, it is characterized by its small adult body length, which is estimated at about 1.65 m. Throughout the Miocene–Pliocene odobenids are characterized by an increase in body size, especially after the extinction of desmatophocids in the late Miocene. The small size of Nanodobenus departs from this trend, demonstrating that there was greater size disparity among odobenids in the mid–late Miocene than previously thought. It is hypothesized that Nanodobenus occupied a niche that was later on occupied by similar-sized otariids, such as Thalassoleon mexicanus, which occurs sympatrically with large odobenids in the overlying Almejas Formation. The Royal Society Publishing 2018-08-08 /pmc/articles/PMC6124023/ /pubmed/30225030 http://dx.doi.org/10.1098/rsos.180423 Text en © 2018 The Authors. http://creativecommons.org/licenses/by/4.0/ Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.
spellingShingle Biology (Whole Organism)
Velez-Juarbe, Jorge
Salinas-Márquez, Fernando M.
A dwarf walrus from the Miocene of Baja California Sur, Mexico
title A dwarf walrus from the Miocene of Baja California Sur, Mexico
title_full A dwarf walrus from the Miocene of Baja California Sur, Mexico
title_fullStr A dwarf walrus from the Miocene of Baja California Sur, Mexico
title_full_unstemmed A dwarf walrus from the Miocene of Baja California Sur, Mexico
title_short A dwarf walrus from the Miocene of Baja California Sur, Mexico
title_sort dwarf walrus from the miocene of baja california sur, mexico
topic Biology (Whole Organism)
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6124023/
https://www.ncbi.nlm.nih.gov/pubmed/30225030
http://dx.doi.org/10.1098/rsos.180423
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