|Egg fossil classification
|Basic shell type:
Garcia et al., 2003
Tipoolithus is an oogenus of fossil egg native to the Irbzer Formation in Morocco. Its classification is uncertain, but it most closely resembles Laevisoolithids, and like members of that oofamily, it was laid by an enantiornithine bird or small theropod.
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.
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.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.
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) affinities.
Dinosaur eggs are the organic vessels in which a dinosaur embryo develops. When the first scientifically documented remains of non-avian dinosaurs were being described in England during the 1820s, it was presumed that dinosaurs had laid eggs because they were reptiles. In 1859, the first scientifically documented dinosaur egg fossils were discovered in France by Jean-Jacques Poech, although they were mistaken for giant bird eggs.
Elongatoolithus is an oogenus of dinosaur eggs found in the Late Cretaceous formations of China and Mongolia. Like other elongatoolithids, they were laid by small theropods, and were cared for and incubated by their parents until hatching. They are often found in nests arranged in multiple layers of concentric rings. As its name suggests, Elongatoolithus was a highly elongated form of egg. It is historically significant for being among the first fossil eggs given a parataxonomic name.
Cairanoolithus is an oogenus of dinosaur egg which is found in Southwestern Europe. The eggs are large and spherical. Their outer surface is either smooth, or covered with a subdued pattern of ridges interspersed with pits and grooves. Multiple fossil egg clutches are known but the nest structure is unclear.
Sphaerovum is an oogenus of dinosaur egg that has only been discovered in South America.
Macroolithus is an oogenus of dinosaur egg belonging to the oofamily Elongatoolithidae. The type oospecies, M. rugustus, was originally described under the now-defunct oogenus name Oolithes. Three other oospecies are known: M. yaotunensis, M. mutabilis, and M. lashuyuanensis. They are relatively large, elongated eggs with a two-layered eggshell. Their nests consist of large, concentric rings of paired eggs. There is evidence of blue-green pigmentation in its shell, which may have helped camouflage the nests.
Subtiliolithus is an oogenus of fossil egg from the Nemegt Formation of Mongolia and the Ohyamashimo Formation of Japan. The eggs are notable for a very thin eggshell. It contains three oospecies: S. hyogoensis, S. kachchhensis and S. microtuberculatus. They were originally classified as a distinct oofamily, Subtiliolithidae, but numerous similarities to Laevisoolithus have led to their reclassification as Laevisoolithid eggs. A complete skeleton of Nanantius valifanovi was found associated with Subtiliolithus eggshells, indicating that the oogenus represents eggs of enantiornithine birds.
Continuoolithus is an oogenus of dinosaur egg found in the late Cretaceous of North America. It is most commonly known from the late Campanian of Alberta and Montana, but specimens have also been found dating to the older Santonian and the younger Maastrichtian. It was laid by an unknown type of theropod. These small eggs are similar to the eggs of oviraptorid dinosaurs, but have a distinctive type of ornamentation.
Dispersituberoolithus is an oogenus of fossil egg, which may have been laid by a bird or non-avian theropod.
Sankofa is an oogenus of prismatoolithid egg. They are fairly small, smooth-shelled, and asymmetrical. Sankofa may represent the fossilized eggs of a transitional species between non-avian theropods and birds.
Paraelongatoolithus is a late Cretaceous oogenus of Chinese fossil egg, classified in the oofamily Elongatoolithidae, which represents the eggs of oviraptorosaurs.
Parvoblongoolithus is an oogenus of fossil dinosaur egg whose small size and unusual shape suggest the possibility that it is a dwarf egg.
Elongatoolithidae is an oofamily of fossil eggs, representing the eggs of oviraptorosaurs. They are known for their highly elongated shape. Elongatoolithids have been found in Europe, Asia, and both North and South America.
Rodolphoolithus is an oogenus of elongatoolithid egg native to Morocco. It is known only from a single partial egg and several eggshell fragments, but it probably had a highly elongated shape like other Elongatoolithids. They have an eggshell with two layers: a mamillary layer and a continuous layer. The mamillary layer is relatively thick ; it is one-half to two-thirds the thickness of the continuous layer. The ornamentation of its outer surface is ramotuberculate, i.e. covered with low, irregular ridges. The pore system cannot be observed due to recrystallization of the fossilized eggshell. Like other Elongatoolithids, Rodolphoolithus was laid by small theropods.
Guegoolithus is an oogenus of fossil egg from the early Cretaceous of Spain. It is classified in the oofamily Spheroolithidae, and was probably laid by an ornithopod dinosaur.
Tubercuoolithus is an oogenus of dinosaur egg from the early Campanian of Montana.
Nipponoolithus is an oogenus of fossil egg native to Japan. It is one of the smallest known dinosaur eggs, and was probably laid by some kind of non-avian maniraptor.
Incognitoolithus is an oogenus of medioolithid fossil bird egg. It is notable for bearing evidence of predation, possibly from a bird pecking the eggshell.
Gobioolithus is an oogenus of fossil bird egg native to Mongolia. They are small, smooth-shelled, and elongated eggs that were first discovered in the 1960s and early 70s during a series of fossil-hunting expeditions in the Gobi desert. Two oospecies have been described: Gobioolithus minor and G. major. The eggs were probably laid in colonial nesting sites on the banks of rivers and lakes.
Arriagadoolithus is the oogenus of fossil eggs which includes the eggs of the alvarezsaurid Bonapartenykus. Fossils of the creature were found in Patagonia; it may have brooded on its eggs.
Nanhsiungoolithus is an oogenus of dinosaur egg from the late Cretaceous of China. It belongs to the oofamily Elongatoolithidae, which means that it was probably laid by an oviraptorosaur, though so far no skeletal remains have been discovered in association with Nanhsiungoolithus. The oogenus contains only a single described oospecies, N. chuetienensis. It is fairly rare, only being know from two partially preserved nests and a few eggshell fragments.