Ageroolithus fontllongensis was first described on the basis of nine eggshell fragments.[1] Some more recently described eggshell fragments have been referred to A.aff.fontllongensis[3] and cf.Ageroolithus.[2] The eggshell has a smooth surface, and at 25–36 mm thick is thinner than most other eggs of the ratite morphotype.[1][2] Erosion and recrystallization heavily affect most Ageroolithus specimens, but a few fragments are well enough preserved to observe the microstructure. It has two structural layers with a sharp dividing line between them.[1] The inner layer, known as the mammillary layer, is composed of wedges and shows distinct growth lines, whereas the outer layer (the prismatic layer[4]) is not clearly divided into units.[1] It has narrow, straight pore canals measuring 15 to 25 μm in diameter.[2][1]
The specimens referred to cf. Ageroolithus by Sellés in 2012 are very similar to Ageroolithus in thickness, ornamentation, and the ratio between prismatic and mammillary layers. They differ from Ageroolithus because their shell is composed of three structural layers instead of two.[2]
^ abcdefghSelles, Albert G. (2012). Oological Record of Dinosaurs in South-Central Pyrenees (SW Europe): Parataxonomy, diversity and biostratigraphical implications (Ph.D.). Universitat de Barcelona.
^Ruiz-Omeñaca, J. I., Canudo, J. I., Aurell, M., Bádenas, B., Barco, J. L., Cuenca-Bescós, G., & Ipas, J. (2004). Estado de las investigaciones sobre los vertebrados del Jurásico Superior y Cretácico Inferior de Galve (Teruel). Estudios Geológicos, 60(3-6), 179-202.
