INVESTIGADORES
FIORELLI lucas Ernesto
artículos
Título:
WATER VAPOR CONDUCTANCE OF THE LOWER CRETACEOUS DINOSAURIAN EGGS FROM SANAGASTA, LA RIOJA, ARGENTINA¬?PALEOBIOLOGICAL AND PALEOECOLOGICAL IMPLICATIONS FOR SOUTH AMERICAN FAVEOLOOLITHID AND MEGALOOLITHID EGGS
Autor/es:
GERALD GRELLET-TINNER; LUCAS FIORELLI; SALVADOR RODRIGO
Revista:
PALAIOS
Editorial:
SEPM-SOC SEDIMENTARY GEOLOGY
Referencias:
Año: 2012 vol. 27 p. 35 - 47
ISSN:
0883-1351
Resumen:
The water vapor conductance (GH2O)
of the neosauropod eggs from the Lower Cretaceous Sanagasta nesting site in La Rioja Province, Argentina,
was examined and compared with other Cretaceous Argentinean oological material.
The 2900 mgH2O/day?Torr GH2O of the Sanagasta eggshells confirms an extremely
moist nesting environment and supports field observations of dug-out nests in a
geothermal setting. The observed thinning of the outer eggshell surface during
incubation increases gas conductance and concomitantly decreases eggshell
mechanical resistance during the late ontogenetic stages, thus facilitating embryonic
development and hatching. The Sanagasta and Entre Ríos Province faveoloolithid eggs display the
highest and comparable GH2O values and share several morphological and
diagenetic characters, indicating comparable nesting strategy in geothermal
settings. However, the faveoloolithid Yaminue´ and La Pampa Province
specimens cluster together with lower GH2O values closer to the megaloolithid
eggs. The GH2O of the megaloolithid egg Megaloolithus patagonicus was
reconsidered and new results are now congruent with other reported
megaloolithid GH2O values. Additionally, we hypothesize that Y-shaped pore
canals of M. patagonicus, which upper sections reach only the top third or half
eggshell thickness and, a wider section in the middle would not compromise the
overall egg mechanical resistance like vertical pores connecting directly the
outer to the inner eggshell surfaces. Such pore spatial arrangement and
geometry would enhance, as the eggshell thins during incubation, a greater GH2O,
GO2 and GCO2 and facilitate embryonic development in high moisture nesting
contents. Overall, data suggests that neosauropod nesting and brooding
behaviors were dependent on elevated moisture nesting environments.