Nuevos registros para la flora cretácica descripta por Halle (1913) en lago San Martín, Santa Cruz, Argentina
Abstract
Resumen. Se han estudiado dos nuevos sitios portadores de plantas fósiles cretácicas, Bajo Comisión 1 y 2, localizados en proximidades del área prospectada originalmente por Thor Halle, al norte del lago San Martín, provincia de Santa Cruz, Argentina. Sus depósitos corresponden a la Formación Kachaike (Albiano tardío - Cenomaniano). Se han identificado alrededor de veinte especies, pertenecientes en su mayoría a pteridófitas, pteridospermas, coníferas y frondes de afinidad sistemática incierta. Briófitas, ben- nettitales, ginkgoales y angiospermas están también presentes, aunque como elementos subordinados. Entre ellos, se reconocieron nuevos taxones para esta unidad: Pachypterisauriculata sp. nov., Brachyphyllum kachaikensis sp. nov. y Thorhalleniadentata gen. et sp. nov. A su vez, se proponen reasignaciones sistemáticas para otros taxones (Gleichenitesjuliensis Herbst en vez de Gleichenites cf. G. micromerus Heer y Phyllopteroides cf. P. laevis Cantrill y Webb en vez de Aspleniteslanceolatus Halle). Existe una evidente si- militud entre las asociaciones Bajo Comisión 1 y 2 con aquella descripta por Halle, lo cual sugiere que estos niveles son, en efecto, los estudiados originalmente por este autor. Abstract. NEWRECORDSOFTHE CRETACEOUSFLORADESCRIBEDBY HALLE (1913) FROM SAN MARTÍN LAKE, SANTA CRUZ, ARGENTINA.Two new sites with Cretaceous fossil plants, Bajo Comisión 1 and 2, have been studied. They are located north of San Martín Lake, Santa Cruz Province, Argentina, and their deposits belong to the Kachaike Formation (Late Albian - Cenomanian). This area was previously studied by Thor Halle who provided the description of a fossil plant assemblage. About twenty species have been recognized at the new sites, mostly belonging to pteridophytes, pteridosperms, conifers as well as morphogenera of uncertain botanical affinity. Bryophytes, bennettites, ginkgophytes and angiosperms are also present as subordinated components. Among them, new taxa are described: Pachypterisauriculata sp. nov., Brachyphyllum kachaikensis sp. nov. and Thorhalleniadentata gen. et sp. nov. In turn, two species, previously described by Halle, have been reassigned to other genera or species: Phyllopteroides cf. P.laevis Cantrill and Webb instead of Aspleniteslanceolatus Halle, and Gleichenitesjuliensis Herbst instead of Gleichenites cf. G. Micromerus Heer and Phyllopteroides cf. P. laevis Cantrill y Webb instead of Aspleniteslanceolatus Halle. There is a considerable resemblance between Bajo Comisión 1 and 2 assemblages and the flora previously described by Halle, suggesting they belong to the same levels.Downloads
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