PaleoBios

The Paleogene cypraeoidean fauna of the northeast Pacific region (NEP), extending from Vancouver Island, British Columbia, Canada southward to Baja California Sur, México, consists of 12 genera, 20 named species (three of which are new), six open-nomenclature species, one Cypraeidae, indeterminate to genus and species, one cf. species, and four nomina dubia. All taxa are figured here. Species reassigned at the genus level are Protocypraea? simiensis (Nelson, 1925) and Luponovula maniobraensis (Squires and Advocate, 1986). Improved documentation of known NEP species include Propustularia kemperae (Nelson, 1925), Grovesia castacensis (Stewart, 1926) [1927]), G. mathewsonii (Gabb, 1864), and Eratotrivia crescentensis (Weaver and Palmer, 1922). The three new species, Subepona leahae, Bernaya kaylinae, and Eocypraea judithsmithae are from the upper lower Eocene Llajas Formation of Simi Valley, Ventura County and Devil Canyon, Los Angeles County, California. Six open-nomenclature species need better preserved material; they are: Bernaya sp., two Protocypraea? sp., Gisortia sp., Eocypraea sp., and Cypraedia sp., as does an indeterminate cypraeid from the Lodo Formation of central California. Nomina dubia are “Bernaya” fresnoensis (Anderson, 1905), “Eocypraea” bayerquei (Gabb, 1864), “Sphaerocypraea” martini (Dickerson, 1914), and “Sulcocypraea” oakvillensis (Van Winkle, 1918). Eratotrivia mackini (Durham, 1944) is herein reassigned to the synonymy of Grovesia mathewsonii (Gabb, 1869). The NEP Paleocene cypraeoidean fauna consists of four genera, a cypraeid of unknown generic affinity, and two nomina dubia. The early Eocene “Capay Stage” cypraeoidean fauna is comprised of eight genera and two nomina dubia. That was during the peak of NEP cypraeoidean biodiversity, which coincided with the “Early Eocene Climate Optimum” (EECO), the warmest time of the Paleogene. At the end of “Capay” time, biodiversity abruptly decreased, and this trend continued to the end of “Domengine Stage” time, when a faunal turnover took place. The cypraeoidean faunas in the subsequent “Tejon Stage” and Galvinian Stage continued to be diminished because of the ongoing cooling of the ocean waters. Continued global cooling eventually caused the disappearance of the thermophilic Paleogene NEP cypraeoideans before the beginning of the Oligocene. Most of the NEP cypraeoidean fauna is very similar morphologically to species found in the Tethys region of Europe, especially France, Italy, and Ukraine. These similar species are indicative that the introduction of most of the NEP cyraeoidean genera into the NEP region was via a westward-directed, warm-water current originating in the ancient Tethys Sea region of western Europe. The point of origin of the Paleocene Propustularia is unknown, and the late Eocene Nuceolaria most likely arrived in the NEP region via a Pacific Ocean route.