title: Micro-CT scan reveals an unexpected high-volume and interconnected pore network in a Cretaceous Sanagasta dinosaur eggshell.
abstract: The Cretaceous Sanagasta neosauropod nesting site (La Rioja, Argentina) was the first confirmed instance of extinct dinosaurs using geothermal-generated heat to incubate their eggs. The nesting strategy and hydrothermal activities at this site led to the conclusion that the surprisingly 7 mm thick-shelled eggs were adapted to harsh hydrothermal microenvironments. We used micro-CT scans in this study to obtain the first three-dimensional microcharacterization of these eggshells. Micro-CT-based analyses provide a robust assessment of gas conductance in fossil dinosaur eggshells with complex pore canal systems, allowing calculation, for the first time, of the shell conductance through its thickness. This novel approach suggests that the shell conductance could have risen during incubation to seven times more than previously estimated as the eggshell erodes. In addition, micro-CT observations reveal that the constant widening and branching of pore canals form a complex funnel-like pore canal system. Furthermore, the high density of pore canals and the presence of a lateral canal network in the shell reduce the risks of pore obstruction during the extended incubation of these eggs in a relatively highly humid and muddy nesting environment.
authors.affiliation: Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-CONICET), Entre Ríos y Mendoza s/n., Anillaco 5301, La Rioja, Argentina emhechenleitner@gmail.com ehechenleitner@crilar-conicet.gob.ar.
authors.forename: E Martín
authors.identifier: http://orcid.org/0000-0002-9538-5681
authors.initials: EM
authors.lastname: Hechenleitner
authors.affiliation: Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-CONICET), Entre Ríos y Mendoza s/n., Anillaco 5301, La Rioja, Argentina Orcas Island Historical Museum, Eastsound, Washington DC, USA.
authors.forename: Gerald
authors.initials: G
authors.lastname: Grellet-Tinner
authors.affiliation: Australian Centre for Microscopy and Microanalysis, University of Sydney, New South Wales 2006, Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: Foley
authors.affiliation: Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-CONICET), Entre Ríos y Mendoza s/n., Anillaco 5301, La Rioja, Argentina.
authors.forename: Lucas E
authors.identifier: http://orcid.org/0000-0001-5254-6935
authors.initials: LE
authors.lastname: Fiorelli
authors.affiliation: School of Biological Sciences (A08), University of Sydney, New South Wales 2006, Australia.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Thompson
mesh_terms: D000818:Animals; D025061:Dinosaurs; D004528:Egg Shell / Q000000981:diagnostic imaging*; D016062:Porosity; D055114:X-Ray Microtomography
keywords: Sanagasta; burrow-nesting; hydrothermal incubation; micro-CT; titanosaurs