Browsing by Autor "Francisco J. Vega"

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    Contribución al alcance estratigráfico de la Formación Agueguexquite (Mioceno), Veracruz, México
    (Sociedad Geológica Mexicana, 2016) Gabriela Pineda-Salgado; Peter Schaaf; Marcelo Aguilar-Piña; Gabriela Solís‐Pichardo; Francisco J. Vega
    La Formacin Agueguexquite aflora en el sureste de Mxico, en el sur de Veracruz y norte de Chiapas. Su edad an no ha sido determinada formalmente, estudios previos han considerado su depsito entre el Mioceno y el Plioceno. Moluscos y muestras de roca de tres localidades de la Formacin Agueguexquite en el estado de Veracruz, fueron recolectados a fin de establecer el alcance estratigrfico de la formacin por medio de edades relativas utilizando foraminferos bentnicos y nanoplancton
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    New Occurrences of Fossil Macrocheira (Brachyura, Inachidae) from the North Eastern Pacific
    (2016) Torrey Nyborg; Brant Nyborg; Alessandro Garassino; Francisco J. Vega
    New specimens of the fossil Macrocheira collected from Eocene to Miocene rocks of Canada and western United States increase the fossil record of the Inachidae (MacLeay, 1838). Macrocheira is represented by only one extant species, M. kaempferi, endemic to Japan and Taiwan. Two fossil species have previously been described from Washington State: M. longirostra (Schweitzer and Feldmann, 1999), from the Eocene Quimper Sandstone, and M. teglandi (Rathbun, 1926), from the Oligocene Makah Formation. Three new species are reported: M. jayi n. sp. from the late Eocene to Oligocene Hesquiat Formation of Vancouver Island, British Columbia, Canada; M. sullivani n. sp. from the late Eocene to early Oligocene Keasey Formation of Oregon State, U.S.A.; and M columbiaensis n. sp. from the early to middle Miocene Astoria Formation of Washington State, U.S.A. Several Macrocheira species have also been reported from the Miocene of Japan; however, their systematic position is tenuous and therefore they are referred to as Macrocheira sp. aff. M. kaempferi. With the description of three new species of Macrocheira, the number of fossil species is increased to five and the genus is now well established in the North Eastern Pacific from the Eocene to Miocene.