A new fossil megamouth shark (Lamniformes, Megachasmidae) from the Oligocene-Miocene of the western United States
2014; Taylor & Francis; Volume: 34; Issue: 2 Linguagem: Inglês
10.1080/02724634.2013.803975
ISSN1937-2809
AutoresKenshu Shimada, Bruce J. Welton, Douglas J. Long,
Tópico(s)Fish Biology and Ecology Studies
ResumoABSTRACT The extant megamouth shark, Megachasma pelagios (Lamniformes: Megachasmidae), is a large filter-feeding fish. We here describe a new species of Megachasma, M. applegatei, sp. nov., a putative sister species of the extant M. pelagios, based on isolated teeth from late Oligocene–early Miocene (late Chattian–Aquitanian) marine deposits in California and Oregon, U.S.A. Although showing a megachasmid tooth design, teeth of M. applegatei, sp. nov., exhibit a wide morphological range and are reminiscent to those of odontaspidid sharks with strong heterodonty. Megachasma applegatei, sp. nov., could have commonly measured approximately 6 m in total length and likely had a wide range of diet, possibly including small fishes and planktonic invertebrates. The fossil record indicates that either M. applegatei, sp. nov., was broadly adapted to a wide bathymetric tolerance or was a nektopelagic feeder over both deep and shallow water habitats. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at http://www.tandfonline.com/UJVP. ACKNOWLEDGMENTS We thank R. Feeney, S. McLeod, V. Rhue, and J. Seigel (LACM), A. Suzumoto (Bernice P. Bishop Museum), and P. Holroyd (UCMP) who made the specimens of Megachasma applegatei, sp. nov., and M. pelagios available for this study. B.J.W. would like to thank L. Barnes (LACM), L. Compagno (Iziko South African Museum), D. Ward (Kent, U.K.), and R. Huddleston (Chevron Oil Field Research Company, La Habra, California) for their help in the early stage of this study. J. Welton provided the revised stratigraphic analysis for the Point Arena locality and assisted B.J.W. in collecting teeth of M. applegatei, sp. nov., from the Skooner Gulch and Nye Mudstone formations. We also thank J. Kriwet and an anonymous reviewer for improving the quality of this paper. Handling editor: Charlie Underwood
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