| Spheroolithidae | |
|---|---|
 | |
| Spheroolithus eggs from China | |
Egg fossil classification  | |
| Basic shell type: | † Dinosauroid-spherulitic |
| Oofamily: | † Spheroolithidae |
| Oogenera | |
Spheroolithidae is an oofamily of dinosaur eggs. It contains Guegoolithus , Spheroolithus , and Paraspheroolithus . [1] Like modern birds, the eggshell membrane formed before the calcareous part of the shell. [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.
The Blesa Formation is a geological formation in Teruel and La Rioja, Spain whose strata date back to the Barremian of the Early Cretaceous. Dinosaur remains as well as eggs are among the fossils that have been recovered from the formation. Along with the fragmentary anhanguerian pterosaur Iberodactylus. While the lower and upper parts of the formation were deposited in a continental setting, the middle portion of the formation is largely nearshore marine, with remains of plesiosaurs.
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.
The Sigou Formation is a Late Cretaceous geologic formation in China. Fossil dinosaur eggs have been reported from the formation, including Dictyoolithus.
Dictyoolithus is an oogenus of dinosaur egg from the Cretaceous of China. It is notable for having over five superimposed layers of eggshell units. Possibly, it was laid by megalosauroid dinosaurs.
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.
Shixingoolithus is an oogenus of dinosaur egg from the Cretaceous of Nanxiong, China.
Protoceratopsidovum is an oogenus of dinosaur egg from Mongolia. Despite its name, it does not represent the eggs of a protoceratopsid, but rather the eggs of maniraptoran theropods.
Macroelongatoolithus is an oogenus of large, fossil theropod eggs. They are known from Asia and from North 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.
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.
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.
Stalicoolithidae is an oofamily of fossil eggs.
Hemifaveoloolithus is an oogenus of fossil dinosaur egg from the Tiantai basin in Zhejiang Province, China. It is a faveoloolithid, having spherical eggs roughly 13 cm in diameter. The shell is distinctive for being composed of four or five superimposed layers of shell units, and the honeycomb-like arrangement of pore canals.
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.
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.
Dictyoolithidae is an oofamily of dinosaur eggs which have a distinctive reticulate organization of their eggshell units. They are so far known only from Cretaceous formations in China.
The Dushihin Formation is an Early Cretaceous (Aptian) geologic formation in the Övörkhangai Province of Mongolia. The formation preserves fossils of Psittacosaurus mongoliensis and fossil eggs described as Trachoolithus faticanus.
Faveoloolithidae is an oofamily of dinosaur eggs. It contains Faveoloolithus, Hemifaveoloolithus, Parafaveoloolithus, and probably Sphaerovum. However, unlike the other Faveoloolthids, Sphaerovum has compactituberculate ornamentation more similar to megaloolithids. Like Dictyoolithidae, the membrane and the calcareous part of the eggshell formed simultaneously instead of forming the membrane before the calcareous like modern birds.
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