INVESTIGADORES
FERNANDEZ Mariela Soledad
congresos y reuniones científicas
Título:
THE FIRST AVIAN EGG FROM RÍO NEGRO PROVINCE, ARGENTINA (ALLEN FORMATION, UPPER CRETACEOUS)
Autor/es:
MARIELA S. FERNÁNDEZ; LEONARDO SALGADO; RODOLFO A. GARCÍA
Lugar:
Caparica
Reunión:
Simposio; VI Symposium of Eggs and babies; 2017
Resumen:
We report the first record of a nearly completed egg, with and Ornithoid eggshell. The egg was found in Salitral Ojo de Agua locality, Río Negro Province; it appeared in Upper Cretaceous (Campanian-Maastrichtian) rocks of the Allen Formation. The egg is exceptionally preserved, including fibers of the testaceous membrane. The egg preserved a single pole, of smooth surface. Its measurements are 53,8 mm in length (long axis) and 30,6 mm in width (short axis). The shape of the egg has been preserved as a molde. Three samples of eggshells have been observed under scanning electron microscope and polarized light microscope. The thickness of the eggshell is about 400µm. The ultrastructure of the eggshells reveals that these eggs have an ornithoid basic type, and a ratite morphotype. The well-developed mammilary layer is 154µm thick and the continuous layer is 251 µm. Ratio CL:ML is 1,6:1. Mammillary layer . The shell microstructure of this egg is consistent with Laevisoolithidae, an ootaxon traditionally associated with enantiornithid birds.The egg is 46,5mm length and 38mm width, the egg has preverved few areas with eggshell and the shape has been preserved as a molde. Eggshell thickness is The fibers are flattened, with a thickness of 1.1µm and a width of 4.8µm each. The fibers have an arrangement similar to those seen in living crocodiles, and display a random arrangement. The preservation of the testaceous membrane suggests extraordinary site conditions. EDAX analysis reported that fibers are enriched in trace of Mg, Al, Si, P, F, and K, element that are also present in one or more examples of both extant and fossil shell membrane.