''Tipoolithus'' is an oogenus of

fossil egg Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg may preserve the remains of t ...

native to the Irbzer Formation in

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...

. Its classification is uncertain, but it most closely resembles Laevisoolithids, and like members of that oofamily, it was laid by an

enantiornithine The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

or small theropod.

Description

''Tipoolithus'' is known from 12 small fragments of eggshell, so characteristics of the whole egg (like size and shape) are unknown. The eggshell is thin, between 0.40-0.65 mm. The continuous layer is up to twice as thick as the mammillary layer.Garcia, G., Tabuce, R., Cappetta, H., Marandat, B., Bentaleb, I., Benabdallah, A., & Vianey-Liaud, M. (2003). "First record of dinosaur eggshells and teeth from the North-West African Maastrichtian (Morocco)." ''Palaeovertebrata'' 32(2-4): 59-69. It has an angusticanaliculate pore system, meaning that the pores a narrow, straight, and widely spaced on the eggshell, which is well adapted to a dry environment to prevent water loss through the eggshell.Carpenter, K. (1999) ''Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction''. Indiana University Press. p. 141. ''Tipoolithus'' resembles '' Porituberoolithus'' in its microstructure and thickness, and resembles '' Subtiliolithus'' in its pore system. The eggshell of ''T. achloujensis'' seems to have dispersituberculate ornamentation, i.e., covered with randomly dispersed nodes, but some fragments show alignments or clusters of nodes, though none are complete enough to determine the full structure of its ornamentation. The nodes have sharp tips.

Parataxonomy

Since the only known eggshells are poorly preserved, classifying ''Tipoolithus'' is difficult. It can certainly be classified into the Ornithoid-Ratite morphotype, and its similarity to ''Subtiliolithus'' suggests Laevisoolithid (

Enantiornithes The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

) affinities.

References

Late Cretaceous reptiles of Africa Fossil parataxa described in 2003 Egg fossils {{eggshell-stub