| Ageroolithus Temporal range: | |
|---|---|
Egg fossil classification  | |
| Basic shell type: | Ornithoid |
| Morphotype: | Ornithoid-ratite |
| Oofamily: | incertae sedis |
| Oogenus: | † Ageroolithus Vianey-Liaud and López-Martínez, 1997 |
| Oospecies | |
| |
Ageroolithus is an oogenus of dinosaur egg. It may have been laid by a theropod. [1]
Ageroolithus fossils are found in the early Maastrichtian Tremp Basin of Lleida, Spain, from the Upper Cretaceous of France, and from the Lower Cretaceous of Galve, Spain. [1]
Ageroolithus was first discovered and described in 1997 by the French paleontologist Monique Vianey-Liaud and the Spanish paleontologist Nieves López Martínez while excavating the Tremp Basin in Spain. [1] Further specimens were discovered in Galve in 1998 and in France in 2000. [2] In 2012, Albert Sellés described Ageroolithus-like eggshells from the Tremp Basin in his PhD thesis at the Universitat de Barcelona. [2]
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]
Ageroolithus has not been placed in any known oofamily, but it is classified in the ratite morphotype, [2] alongside Elongatoolithidae, Laevisoolithidae, Medioolithidae, and Ornitholithidae. [5] It contains a single oospecies: A. fontllongensis. [2]
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.
Pseudogeckoolithus is an oogenus of dinosaur egg. It is known from several fragments of eggshells. The outer surface of these are covered with little knobs and nodes. Some of the pores in the eggshell open through these nodes, similar to modern geckos, but unique among the dinosauroid-prismatic group of eggs. However, the microstructure of Pseudogeckoolithus shows that it is not actually of the geckoid type. It is possible that these eggs represent a new basic group of fossil eggs.
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.
Phaceloolithus is an oogenus of dinosaur egg found in the Fenshui'ao Formation of the Dongting Basin of the Hunan Province of China. The eggs have a subspherical shape, measuring up to 168 mm on the long axis, and having a very thin shell.
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.
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 the once-developing embryo inside, in which case it also contains body fossils. A wide variety of different animal groups laid eggs that are now preserved in the fossil record beginning in the Paleozoic. Examples include invertebrates like ammonoids as well as vertebrates like fishes, possible amphibians, and reptiles. The latter group includes the many dinosaur eggs that have been recovered from Mesozoic strata. Since the organism responsible for laying any given egg fossil is frequently unknown, scientists classify eggs using a parallel system of taxonomy separate from but modeled after the Linnaean system. This "parataxonomy" is called veterovata.
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.
Montanoolithus is an oogenus of fossil egg found in Montana and Alberta. They were probably laid by a dromaeosaur or a caenagnathid.
Laevisoolithidae is an oofamily of fossil eggs belonging to the Ornithoid-ratite morphotype. Their eggshells are smooth and very thin, typically less than a millimeter thick. Laevisoolithids may be the eggs of Enantiornithid birds. Eggs of the family were found in the Grès à Reptiles Formation of France and the Nemegt Formation of Mongolia.
Pseudomegaloolithus is an oogenus of fossil Megaloolithid egg from Morocco. It is known from eggshell fragments which are distinguished from other Megaloolithid eggs because of its thin shells, fan-shaped eggshell units, and the structure of the nodes and ridges on the eggshell surface. Some egg fragments from India, France, and Peru may actually represent specimens of Pseudomegaloolithus.
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.
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.
Mycomorphoolithus is an oogenus of fossil eggs found in Spain and England. They possibly represent eggshells of non-eusuchian crocodylomorphs, and are similar to, but not part of, the Krokolithidae.
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.
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.
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