{"pk":41771,"title":"The dentition of the extinct megamouth shark, Megachasma applegatei (Lamniformes: Megachasmidae), from southern California, USA, based on geometric morphometrics","subtitle":null,"abstract":"Megachasma applegatei\n is an extinct megamouth shark (Lamniformes: Megachasmidae) commonly found in late Oligocene‒early Miocene marine deposits of the western USA, that is known only from isolated teeth exhibiting odontaspidid tooth design. In this study, we investigated the tooth morphometry of the extant megamouth shark (\nMegachasma pelagios\n) and smalltooth sandtiger (\nOdontaspis ferox\n: Odontaspididae) to aid in the reconstruction of the dentition of \nM. applegatei\n based on the tooth morphometry of 207 isolated fossil teeth from the lower Miocene Jewett Sand of southern California. Our landmark-based geometric morphometric analyses show that \nM. applegatei\n not only possesses a wider morphological range of teeth than\n M. pelagios\n, but also has morphological variation that can be corresponded to different tooth types in \nO. ferox\n, forming a unique heterodont dentition typical for macrophagous lamniform sharks known as the ‘lamnoid tooth pattern’. Therefore, our study suggests that the dentition of\n M. applegatei\n could have also exhibited the lamnoid tooth pattern. In order to reconstruct the dentition of \nM. applegatei\n, specific tooth specimens plotted on the morphospace of \nM. applegatei\n were selected by identifying teeth of specific tooth types in the corresponding morphospaces of \nM. pelagios\n and \nO. ferox\n. However, because the total number of teeth per each dental series cannot be ascertained, we generated three sets of reconstructed dentition for \nM. applegatei\n. The first set modeled the dentition of \nO. ferox\n, the second set representing an intermediate form between\n O. ferox\n and \nM. pelagios\n, and the third set mimicking the dentition of \nM. pelagios\n, with the assumption that the true dental pattern for\n M. applegatei\n lies somewhere between the first and third tooth sets, possibly close to the second set. This study represents the first case of using geometric morphometrics to reconstruct the dentition of an extinct shark.","language":"en","license":{"name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0","short_name":"CC BY-NC-SA 4.0","text":"<p><!-- x-tinymce/html --></p>\n<p>Readers are free to:</p>\n<ul>\n<li><strong>Share</strong> — copy and redistribute the material in any medium or format</li>\n<li><strong>Adapt</strong> — remix, transform, and build upon the material<br><br>The licensor cannot revoke these freedoms as long as you follow the license terms.</li>\n</ul>\n<p>Under the following terms:</p>\n<ul>\n<li><strong>Attribution</strong> — You must give appropriate credit , provide a link to the license, and indicate if changes were made . You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.</li>\n<li><strong>NonCommercial</strong> — You may not use the material for commercial purposes .</li>\n<li><strong>ShareAlike</strong> — If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.<br><br>No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.</li>\n</ul>\n<p>Notices:</p>\n<p>You do not have to comply with the license for elements of the material in the public domain or where your use is permitted by an applicable exception or limitation.</p>\n<p>No warranties are given. The license may not give you all of the permissions necessary for your intended use. For example, other rights such as publicity, privacy, or moral rights may limit how you use the material.</p>","url":"https://creativecommons.org/licenses/by-nc-sa/4.0"},"keywords":[{"word":"dentition, fossil, lamnoid tooth pattern, Megachasma, Megachasmidae, Odontaspis"}],"section":"Article","is_remote":true,"remote_url":"https://escholarship.org/uc/item/4990r1hx","frozenauthors":[{"first_name":"Alexandra","middle_name":"M.","last_name":"Krak","name_suffix":"","institution":"DePaul University","department":"None"},{"first_name":"Kenshu","middle_name":"","last_name":"Shimada","name_suffix":"","institution":"DePaul University","department":"None"}],"date_submitted":"2023-02-10T15:39:30Z","date_accepted":"2023-02-10T15:39:30Z","date_published":"2023-02-10T08:00:00Z","render_galley":null,"galleys":[{"label":"","type":"pdf","path":"https://journalpub.escholarship.org/ucmp_paleobios/article/41771/galley/31232/download/"}]}