| Dispersituberoolithus Temporal range: | |
|---|---|
Egg fossil classification  | |
| Basic shell type: | Ornithoid |
| Morphotype: | † Ornithoid-prismatic |
| Oogenus: | † Dispersituberoolithus Zelenitsky, Hills & Currie, 1996 |
| Oospecies | |
| |
Dispersituberoolithus is an oogenus of fossil egg, which may have been laid by a bird or non-avian theropod. [1]
The eggshell fragments now classified as Dispersituberoolithus were collected between 1987 and 1995 by field crews working for the Royal Tyrrell Museum of Palaeontology. They were first described in 1996 by D.K. Zelenitsky and L.V. Hills, two paleontologists in Department of Geology and Geophysics at the University of Calgary, together with P.J. Currie from the Royal Tyrrell Museum. [1]
Dispersituberoolithus exilis is known from several eggshell fragments collected at Little Diablo's Hill at Devil's Coulee, southern Alberta. This is part of Oldman Formation, which is dated to the late Campanian. [1]
Dispersituberoolithus is one of the few fossil eggs of the ornithoid-prismatic morphotype. [1] The outer surface of its eggshell exhibits what is called dispersituberculate ornamentation, i.e. the shell is covered with randomly distributed nodes. Dispersituberoolithus was named for this pattern. Its shell is 0.26 to 0.28 mm thick, and is made up of three structural layers. The innermost layer, called the mammillary layer, is half the thickness of the continuous layer and twice the thickness of the external zone. The boundary between the continuous and the mammillary layers exhibits a squamatic ultrastructure. [1] It has an angusticanaliculate pore system, which means that its pores are long, narrow, and straight. [1] [2]
Dispersituberoolithus is classified in the ornithoid-prismatic morphotype (also called the neognathous morphotype). [1] [3] It has not been assigned to any known oofamily. Only one oospecies has been named: D. exilis. [1]
Since no embryos of D. exilis are known, it is impossible to determine with certainty whether it was laid by a bird or a non-avian theropod. [4] Zelenitsky et al. (1996) believed it to be the eggs of a bird because its eggshell has an external zone. [1] However the sculpted outer surface of Dispersituberoolithus's shell is unlike bird eggs, and since some non-avian dinosaurs are known to have a three-layered eggshell, the presence or absence of the external zone cannot be reliably used to distinguish avian eggs from non-avian. [4]
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.
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.
Ageroolithus is an oogenus of dinosaur egg. It may have been laid by a 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.
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.
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.
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.
Trigonoolithus is an oogenus of dinosaur egg, representing a basal prismatoolithid. Its eggshell, like avian eggs, is composed of three structural layers, but cladistic analysis suggests that its parent was a non-avian theropod.
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.
Pachycorioolithus is an oogenus of small, thin-shelled fossil egg from the early Cretaceous in China. It probably belongs to a bird, though there is a possibility the parent was a non-avian theropod. It was named in 2016, based on a single specimen found in Zhejiang.
Plagioolithus is an oogenus of fossil egg. It is from the Early Cretaceous of Japan. It was probably laid by a bird, making it the oldest known fossil bird egg.
