| Arriagadoolithus Temporal range: | |
|---|---|
Egg fossil classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | † Alvarezsauridae |
| Oofamily: | † Arriagadoolithidae |
| Oogenus: | † Arriagadoolithus Agnolin et al., 2012 |
| Oospecies | |
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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. [1]
Arriagadoolithus patagoniensis is known from two partial eggs both found associated with a skeleton of Bonapartenykus ultimus . The eggs are about 77 mm (3.0 in) in maximum width, but the length of the eggs and whether or not they were symmetric are unknown. [1]
Unlike most non-avian dinosaur eggs, [2] Arriagadoolithus's shell has three layers (external, prismatic, and mammillary). The shell is approximately 1 mm (0.039 in) thick. [1]
The outer surface of its eggshell is covered with two distinct ornamentation patterns: the unique dendro-reticulate ornament, made up of randomly interconnecting ridges with nodes along the ridges or where they intersect; and the plexi-ramo-tuberculate ornament, made up of widely spaced irregularly shaped nodes and ridges. The dendro-reticulate ornamentation was found only on fragments. [1]
The pores of Arriagadoolithus are unusually wide, with funnel-like openings up to 271 μm in diameter. The pores cut straight through the eggshell (representing a tubocanaliculate pore system) or obliquely (obliquicanaliculate pore system). [1]
Even though they contain no embryos, Arriagadoolithus eggs are known to belong to the alvarezsaurid dinosaur Bonapartenykus because the fossils were found in close association. It is possible that the Bonapartenykus was sitting on the eggs, representing another instance of brooding in dinosaur parents such as oviraptorids or Troodon . However, no nest was found associated with the remains, so Agnolin et al. 2012 believed that brooding is implausible. They alternately suggested that the eggs may not have been laid yet and were still inside the Bonapartenykus when they were fossilized. [1]
Fossilized remains of fungal growths were discovered on the inside of the eggshell, [1] similar to the discovery of fungi within a turtle egg in China. [3] The fungus probably contaminated the Arriagadoolithus eggs while they still contained organic material. [1]
Arriagadoolithus is a monotypic oogenus containing A. patagoniensis. It is classified alongside Triprismatoolithus in the oofamily Arriagadoolithidae. [1]
The two eggs of Arriagadoolithus were found in Río Negro Province, Patagonia, Argentina, though presumably the same type of eggs existed throughout Bonapartenykus's distribution, including Neuquén Province as well. It is dated to the Santonian to Maastrichtian stages of the Upper Cretaceous. [1]
Patagonykus is a genus of theropod dinosaur from the Upper Cretaceous of Argentina. This alvarezsauroid was discovered in exposures of the Portezuelo Formation (Turonian-Coniacian) of the Rio Neuquén Subgroup in the Neuquén Basin, Neuquen Province of Patagonia, Argentina. The holotype consists of an incomplete but well-preserved skeleton, lacking a skull, but including many vertebrae, the coracoids, a partial forelimb, pelvic girdle, and hindlimbs. Patagonykus has been classed with the Alvarezsauridae, a family which includes such taxa as the Mongolian Mononykus and the Argentinian Alvarezsaurus. In 2010 Gregory S. Paul estimated its length at 1 meter and its weight at 3.5 kg.
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.
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.
Bonapartenykus is a monospecific genus of alvarezsauroid dinosaur from Argentina that lived during the Late Cretaceous (Campanian-Maastrichtian) in what is now the upper Allen Formation of the Río Negro Province. The type and only species, Bonapartenykus ultimus, is known from a nearly articulated but partial skeleton that was found in close association to two incomplete eggs and several clusters of eggshells belonging to the oogenus Arriagadoolithus. Bonapartenykus was named in 2012 by Federico L. Agnolin, Jaime E. Powell, Fernando E. Novas and Martin Kundrát. Bonapartenykus has an estimated length of 2.5 m (8.2 ft) and weight of 72 kg (159 lb), making it the largest member of the clade Alvarezsauroidea.
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.
Paraelongatoolithus is a late Cretaceous oogenus of Chinese fossil egg, classified in the oofamily Elongatoolithidae, which represents the eggs of oviraptorosaurs.
Arriagadoolithidae is an oofamily of fossil eggs, representing the eggs of Alvarezsaurs.
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.
Polyclonoolithus is an oogenus of fossil dinosaur egg. It is from the Early Cretaceous of Gansu, China. They have distinctive, branching eggshell units, which may represent the original form of spheroolithids.
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.
Tubercuoolithus is an oogenus of dinosaur egg from the early Campanian of Montana.
Triprismatoolithus is an oogenus of dinosaur egg native to Teton County, Montana. It is classified in the oofamily Arriagadoolithidae, the eggs of alvarezsaurs.
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.
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.
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