{"pk":41760,"title":"The earliest \nAncistrolepis\n (Gastropoda: Buccinidae) and its geologic implications","subtitle":null,"abstract":"The buccinid gastropod \nAncistrolepis carolineae\n Squires, 1984 is the earliest known and shallowestmarine species belonging to the extant genus\n Ancistrolepis\n Dall, 1895, which is endemic to the NorthPacific region. This species is of late early Eocene (Ypresian Stage) age and is about 7 million years older than the previously oldest known record (late Eocene) of the genus. This rare species occursat several localities in a 1-m thick bed (“Stewart bed”) of fossiliferous shallow-marine sandstone within the Llajas Formation, on the north side of Simi Valley, Ventura County, southern California.The “Stewart bed” contains a rich fauna of subtropical mollusks and other invertebrates, which lived just below effective wave base, at the distal edge of a braid delta, immediately adjacent to an upper bathyal prodelta/slope environment, where a rich microfauna of calcareous nannofossils and benthic foraminifers lived. Dispersal of \nA. carolineae\n would have been either via drifting of buoyant “pouches” containing its non-planktonic eggs or by rafting of its adults in buoyant plant material debris. The dispersal of \nA. carolineae\n northward coincided with the cooling of the NorthPacific waters during the late Eocene, thereby providing the opportunity for Ancistrolepis to adapt to living in bathyal waters and also to living in association, in some cases, with chemosynthetic (methane) cold seeps.","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":"early Eocene, California, shallow marine, subtropical, Llajas Formation"}],"section":"Article","is_remote":true,"remote_url":"https://escholarship.org/uc/item/1cd5f6pz","frozenauthors":[{"first_name":"Richard","middle_name":"L.","last_name":"Squires","name_suffix":"","institution":"Professor Emeritus, Department of Geological Sciences, California State University, 18111 Nordhoff Street, Northridge, California,\n91330-8266, USA; Research Associate, Invertebrate Paleontology Department, Natural History Museum of Los Angeles County,\n900 Exposition Boulevard, Los Angeles, California, 90007","department":"None"}],"date_submitted":"2022-04-08T13:20:41-07:00","date_accepted":"2022-04-08T13:20:41-07:00","date_published":"2022-04-08T00:00:00-07:00","render_galley":null,"galleys":[{"label":"","type":"pdf","path":"https://journalpub.escholarship.org/ucmp_paleobios/article/41760/galley/31226/download/"}]}