CECOAL   02625
CENTRO DE ECOLOGIA APLICADA DEL LITORAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Morphological study of the 'conchostracans' (Crustacea - Spinicaudata) from the Jurassic-Cretaceous Cañadón Calcáreo Formation Chubut, Argentina
Autor/es:
GALLEGO, O.F.; CABALERI, N.; ZACARÍAS, I.A.; SHEN, Y.B.
Lugar:
Gral. Roca Río Negro
Reunión:
Congreso; 11° Congreso de la Asociación Paleontológica Argentina; 2016
Institución organizadora:
Asociación Paleontológica Argentina
Resumen:
The Cañadón Calcáreo Formation (Cañadón Asfalto Basin) crops out in the eastern margin of the middle valley of Chubut River in the central region of the Extrandean Patagonia. Thissequence of Upper Jurassic-Cretaceous discussed age shares a particular association of'conchostracans' (spinicaudatans) composed of species of the families Antronestheriidae andJilinestheriidae. The latter family has Cretaceous affinities between South America and Asia,in particular the presence of genus Nemestheria Zhang and Chen, 1964, recorded for theCenomanian of China. New studies of specimens of the genus Nemestheria from CañadónCalcáreo Formation (7394 CTES-PZ) allow us to present in this communication themorphological characteristics of the carapace undertaken by scanning electron microscopy.The specimen has a shell of small size (length 4.8 mm - 2.7 mm height) with an oval outline,straight dorsal margin, and the umbo with subterminal position; with about 22 lines of evenlyspaced growth bands in the ventral and narrow closer to the dorsal region. The SEM imagesshowed that the radial lirae ornamentation is long (0.12 mm) interspersed with short lirae(0.05 mm) at the bottom of the bands ornamentation appears as a crosslinked radial lirae. Thisanalysis provides new information that enables complete the diagnostic features of the genus.The presence of this taxon in South America provides additional evidence on the alreadydefined relations between the South American forms and Jurassic-Cretaceous species ofChina, and expands the evolutionary scenario and distribution of this group during theMesozoic globally.