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Re: Guegoolithus, new oogenus from the Lower Cretaceous of Spain



Sorry, this is the link to the article:
http://www.sciencedirect.com/science/article/pii/S0195667114001098


> Available online today:
>
> Moreno-Azanza, M., J.I. Canudo & J.M. Gasca. 2014. Spheroolithid
> eggshells in the Lower Cretaceous of Europe. Implications for eggshell
> evolution in ornithischian dinosaurs. Cretaceous Research, 51: 75-87.
>
> Abstract:
> Early Cretaceous spheroolithid eggshells have always been extremely
> scarce, unlike their putative egg layers, ornithopod dinosaurs, which
> are ubiquitous in Early Cretaceous ecosystems. In this paper, we
> re-evaluate eggshells previously assigned to the oofamily
> Elongatoolithidae, an oofamily related to derived theropod dinosaurs
> (including maniraptorans and oviraptorids), and reassign them to the
> oofamily Spheroolithidae, on the basis of the lack of a squamatic
> ultrastructure, and the presence of a prolatocanaliculate pore system
> and undulating extinction, typical of spheroolithid eggshells. We
> erect a new oogenus, Guegoolithus to include material previously
> reported as Macroolithus turolensis Amo-Sanjuan, Canudo and
> Cuenca-Bescos 2000, and new material from several lower Barremian
> localities of the Maestrazgo Basin in Spain. Guegoolithus eggshells
> exhibit an acicular radial ultrastructure in the lower part of the
> shell units, which develops into a tabular radial ultrastructure in
> the upper part, giving an appearance of a two-layered eggshell in thin
> sections that is not seen in SEM pictures. These features fill the gap
> between the two-layered prismatic eggshell of ceratopsians and the
> prolatospherulitic ornithopod eggshell of derived hadrosaurs.
>
> Keywords:
> Ornithopod, Macroolithus, Elongatoolithidae, Parataxonomy, Spain,
> Maestrazgo Basin
>
> -------------------------------------------
> Jose Ignacio Ruiz-Omenaca
> Museo del Jurasico de Asturias (MUJA)
> E-33328 Colunga, Spain
> www.dinoastur.com
> www.museojurasicoasturias.com
> www.aragosaurus.com
> -------------------------------------------