[MARMAM] New publication - Tsai and Ando 2015 Aetiocetidae niche partitioning

Cheng-Hsiu Tsai cheng-hsiu.tsai at otago.ac.nz
Mon Apr 13 14:22:21 PDT 2015


Dear colleagues

We are pleased to announce a new article, reporting a large Morawanocetus-like animal
from the Oligocene of Hokkaido, suggesting niche partitioning in Oligocene toothed
mysticetes.

Tsai, CH and Ando, T. 2015. Niche partitioning in Oligocene toothed mysticetes (Mysticeti: Aetiocetidae).
Journal of Mammalian Evolution doi: 10.1007/s10914-015-9292-y

Available at: http://link.springer.com/article/10.1007/s10914-015-9292-y
or email Tsai: cheng-hsiu.tsai at otago.ac.nz<mailto:cheng-hsiu.tsai at otago.ac.nz>; craniata at gmail.com<mailto:craniata at gmail.com>

Abstract
Niche partitioning has long been considered to be a fundamental part of speciation and difference in body size is a straightforward proxy for ecology and niche partitioning. Here we report a new aetiocetid specimen from the upper part of Morawan Formation (Oligocene; late Chattian, ~26–24 Ma), Ashoro, Hokkaido, Japan. This specimen comprises an isolated left squamosal and an isolated left periotic; the morphology of the squamosal is distinguishable from all aetiocetids, but shows a close match with the aetiocetid Morawanocetus yabukii in that: the dorsal margin of the zygomatic process of the squamosal is twisted dorsomedially; the zygomatic process expands dorsoventrally; the zygomatic process is transversely thin; and the anterior tip of the zygomatic process is acutely tapered. The estimated body size of this Morawanocetus-like specimen is ca. 8 m, almost twice the size of all known aetiocetids (3–4 m). Moreover, the preserved periotic reveals structures that are otherwise poorly known in aetiocetids. This large Morawanocetus-like aetiocetid sheds new light on niche partitioning of Oligocene toothed mysticetes and evolution of body size in Mysticeti.

Regards and all the best,
Tsai

Cheng-Hsiu Tsai (蔡政修)
PhD student, Department of Geology, University of Otago
360 Leith Walk (Courier) or PO Box 56 (Postal)
Dunedin 9054, New Zealand
Email: cheng-hsiu.tsai at otago.ac.nz<mailto:cheng-hsiu.tsai at otago.ac.nz>; craniata at gmail.com<mailto:craniata at gmail.com>

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