A New Fossil Megamouth Shark (Lamniformes, Megachasmidae) from the Oligocene—Miocene of the Western United States

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 Ch...

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Bibliographic Details
Published in:Journal of vertebrate paleontology 2014-03, Vol.34 (2), p.281-290
Main Authors: Shimada, Kenshu, Welton, Bruce J, Long, Douglas J
Format: Article
Language:English
Subjects:
Dental crowns
Dentition
Fossils
Holotypes
Lamniformes
Marine
Mathematical cusps
Megachasma
Megachasma pelagios
Megachasmidae
Paratypes
Sharks
Taxa
Teeth
Vertebrate paleontology
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Summary: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.
ISSN:0272-4634
1937-2809
DOI:10.1080/02724634.2013.803975