[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Sauropod eggs in moist nests

From: Ben Creisler

This paper came out last month but I don't think was mentioned on the DML:

Gerald Grellet-Tinner, Lucas Ernesto Fiorelli, and Rodrigo Brincalepe
Salvador (2012)
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.
PALAIOS 27: 35–47
DOI: 10.2110/palo.2011.p11-061r

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 Yaminué 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.