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Late Cretaceous bird nesting colony site from Argentina

From: Ben Creisler

A new paper in PLoS ONE:

Mariela S. Fernández, Rodolfo A. García, Lucas Fiorelli, Alejandro
Scolaro, Rodrigo B. Salvador, Carlos N. Cotaro, Gary W. Kaiser &
Gareth J. Dyke (2013)
A Large Accumulation of Avian Eggs from the Late Cretaceous of
Patagonia (Argentina) Reveals a Novel Nesting Strategy in Mesozoic
PLoS ONE 8(4): e61030.

We report the first evidence for a nesting colony of Mesozoic birds on
Gondwana: a fossil accumulation in Late Cretaceous rocks mapped and
collected from within the campus of the National University of
Comahue, Neuquén City, Patagonia (Argentina). Here, Cretaceous
ornithothoracine birds, almost certainly Enanthiornithes, nested in an
arid, shallow basinal environment among sand dunes close to an
ephemeral water-course. We mapped and collected 65 complete,
near-complete, and broken eggs across an area of more than 55 m2.
These eggs were laid either singly, or occasionally in pairs, onto a
sandy substrate. All eggs were found apparently in, or close to, their
original nest site; they all occur within the same bedding plane and
may represent the product of a single nesting season or a short series
of nesting attempts. Although there is no evidence for nesting
structures, all but one of the Comahue eggs were half-buried upright
in the sand with their pointed end downwards, a position that would
have exposed the pole containing the air cell and precluded egg
turning. This egg position is not seen in living birds, with the
exception of the basal galliform megapodes who place their eggs within
mounds of vegetation or burrows. This accumulation reveals a novel
nesting behaviour in Mesozoic Aves that was perhaps shared with the
non-avian and phylogenetically more basal troodontid theropods.