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Fossil bird egg from Upper Cretaceous of Brazil



Ben Creisler
bcreisler@gmail.com

A new online paper:

Júlio Cesar. de A. Marsola, Gerald Grellet-Tinner, Felipe C.
Montefeltro, Juliana M. Sayão, Annie Schmaltz Hsiou & Max C. Langer
(2014)
The first fossil avian egg from Brazil.
Alcheringa (advance online publication)
DOI:10.1080/03115518.2014.926449
http://www.tandfonline.com/doi/full/10.1080/03115518.2014.926449#.U5h8hfldXTo

In contrast to the rich record of eggs from non-avian dinosaurs,
complete eggs attributable to Mesozoic birds are relatively scarce.
Nevertheless, several well-preserved specimens have been discovered
over the last three decades revealing functional and phylogenetic
characters that shed light on the breeding strategies of extinct
birds. Here we report the first fossil avian egg from Brazil, which
was discovered in Upper Cretaceous strata of São Paulo in the
southeastern part of the country. The taxonomic identity and
structural features of the biomineralized tissues were determined
using a combination of Scanning Electron Microscopy, Wave Dispersion
Energy analyses and Computed Tomography. These show that the
125.5-μm-thick shell of the 31.4 × 19.5 mm egg incorporates three
structural layers of similar thickness with both prismatic and
aprismatic boundaries. Close similarity between the Brazilian bird egg
and those of enantiornithines from the Upper Cretaceous Bajo de la
Carpa Formation (Río Colorado Subgroup) of Argentina advocates
affinity with basal Ornithothoraces. Furthermore, coherency of their
depositional contexts might imply a compatible preference for breeding
and nesting environments.