| Mycomorphoolithus Temporal range: | |
|---|---|
Egg fossil classification  | |
| Basic shell type: | † Crocodiloid |
| Oogenus: | † Mycomorphoolithus Moreno-Azanza et al., 2015 |
| Oospecies | |
| |
Mycomorphoolithus (meaning "fungus-shaped stone egg") 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. [1]
M. kohringi is known from three formations in the Maestrazgo Basin in Spain: the El Castellar Formation, the Mirambel Formation, and the Blesa Formation, plus La Huergina and El Collado Formations in Spain, [2] all of which are Barremian age. Also, eggshell fragments referred to Mycomorphoolithus sp. are known from the Purbeck Group in England, which is dated to the Berriasian. [1]
Mycomorphoolithus were first discovered (though not yet named) in 1990 by German paleontologist Rolph Köhring, who believed them to be the eggs of batagurine turtles. [3] In 2015, the oogenus and oospecies Mycomorphoolithus kohringi was named by Moreno-Azanza et al. in honor of Köhring, based on the discovery of several fossil eggshell fragments in the Maestrazgo Basin of Spain. [1]
From their discovery in 1990 until the description of the oospecies in 2015, paleontologists have conjectured many possible identities for the parent of Mycomorphoolithus eggs. Köhring originally conjectured that they were the eggs of batagurine turtles, but later he believed them to be dinosaurian. Eggshell fragments discovered in England were described by Ensom in 2002, which are now referred to Mycomorphoolithus sp., were classified in the dinosauroid-spherulitic morphotype, and tentatively assigned to Faveoloolithidae (probably the eggs of sauropods [4] ). However, the 2015 description by Moreno-Azanza et al. shows that they are neither turtle nor dinosaur eggs, and suggests they were laid by a non-eusuchian crocodylomorph. [1]
Mycomorphoolithus is most notable for the mushroom-like shape of its eggshell units: They are very thin at the base, but suddenly increase dramatically in width about halfway through the eggshell. The eggshell is on average 524 micrometers thick. The pores have highly variable shape and size, and are densely distributed across the eggshell, ranging from 4 to 10 pores per square millimeter. [1]
Similar to krokolithids, and unlike dinosaur eggs, Mycomorphoolithus's eggshell units are isolated, have a blocky extinction pattern, and lack organic cores. It furthermore shares a single layered eggshell with Bauruoolithus , an oogenus of South American krokolithid. However, Krokolithes and modern crocodylians have multi-layered eggshells and a different ultrastructure from Mycomorphoolithus. [1]
Due to their unique microstructure, classifying Mycomorphoolithus has been difficult. It has many similarities to the oofamily Krokolithidae, but the differences were significant enough for Moreno-Azanza et al. (2015) to classify it outside, but closely related to, that oofamily. Because of its resemblance to krokolithids and to modern crocodylian eggs, as well as the presence of non-eusuchian crocodilomorphs at the same sites as Mycomorphoolithus, it is conjectured to be the fossil eggs laid by a non-eusuchian crocodylomorph. [1]
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.
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.
Sphaerovum is an oogenus of dinosaur egg that has only been discovered in South America.
Shixingoolithus is an oogenus of dinosaur egg from the Cretaceous of Nanxiong, China.
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.
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.
Coralloidoolithus is an oogenus of dinosaur egg from the Tiantai Basin in Zhejiang Province, containing a single known oospecies C. shizuiwanensis. Formerly, it was classified in the oogenus Paraspheroolithus; however, it was considered sufficiently different to be classified in its own genus. C. shizuiwanensis is similar to Stalicoolithus, leading to their classification in the same family, Stalicoolithidae.
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.
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.
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.
Suchoolithus is an oogenus of crocodylomorph eggs from the late Jurassic of Portugal. They are notable for their small size, and for being among the oldest known crocodylomorph 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.
