Misplaced Pages

#528471

25-628: Elongatoolithidae is an oofamily of fossil eggs, representing the eggs of oviraptorosaurs (with the exception of the avian Ornitholithus ). They are known for their highly elongated shape. Elongatoolithids have been found in Europe, Asia, and both North and South America. Elongatoolithids have a very broad distribution. They have been found across Asia and the US , as well as in Spain , France , and Argentina , with ages ranging from lower Cretaceous to

50-773: A name given provisionally by Professor J. Buckman to a group of eggs which Buckman believed were laid by a teleosaur . However, modern scientists no longer think it is possible to determine what kind of reptile laid these eggs. In 1859, the first scientifically documented dinosaur egg fossils were discovered in southern France by a Catholic priest and amateur naturalist named Father Jean-Jacques Poech , however he thought they were laid by giant birds. The first scientifically recognized dinosaur egg fossils were discovered serendipitously in 1923 by an American Museum of Natural History crew while looking for evidence of early humans in Mongolia. Egg discoveries continued to mount all over

75-552: A time. Also, the relatively large size of the eggs indicates that a female could not lay more than one pair at a time. In the basic-type and morphotype scheme for eggshell classification (which is now typically disused), elongatoolithids are of the Ornithoid basic type and Ornithoid-Ratite morphotype. They are similar to the Troodon eggshells, which are now classified in the oofamily Prismatoolithidae . Elongatoolithidae contains

100-409: Is covered by a membrane of connective tissue called the periosteum . Beneath the cortical bone layer is a layer of spongy cancellous bone . Inside this is the medullary cavity which has an inner core of bone marrow, it contains nutrients and help in formation of cells, made up of yellow marrow in the adult and red marrow in the child. There are two congenital disorders of the long bones. In

125-417: Is not always followed. They are divided up into several basic types: Testudoid, Geckoid, Crocodiloid, Dinosauroid-spherulitic, Dinosauroid-prismatic, and Ornithoid. Veterovata does not always mirror the taxonomy of the animals which laid the eggs. The oogenus level parataxonomy of Veterovata, following Lawver and Jackson (2014) for Testudoid, Hirsch (1996) for Geckonoid eggs, and Mikhailov et al. (1996) for

150-744: The Devonian and spanning into the Cenozoic era . The eggs of many different fish taxa have contributed to this record, including lobe-finned fish , placoderms , and sharks . Occasionally eggs are preserved still within the mother's body, or associated with fossil embryos . Some fossil eggs possibly laid by fish cannot be confidently distinguished from those laid by amphibians . Several fossilized fish or amphibian eggs have been classified as ichnogenera, including Mazonova , Archaeoovulus , Chimaerotheca , Fayolia , and Vetacapsula . The fossil record of reptile eggs goes back at least as far as

175-556: The Early Permian . However, since the earliest reptile eggs probably had soft shells with little preservation potential , reptilian eggs may go back significantly farther than their fossil record. Many ancient reptile groups are known from egg fossils including crocodilians , dinosaurs , and turtles. Some ancient reptiles, like ichthyosaurs and plesiosaurs are known to have given live birth and are therefore not anticipated to have left behind egg fossils. Dinosaur eggs are among

200-531: The Paleocene . Elongatoolithids are, as their name suggests, highly elongated eggs; they are at least twice as long as they are wide. They vary widely in size, ranging from the 7 cm long Elongatoolithus chichengshanensis to the gigantic 60 cm Macroelongatoolithus . All known clutches are laid in concentric circles of paired eggs, sometimes in up to three superimposed layers. Elongatoolithid eggshells are made up of two layers: The inner layer, called

225-463: The fossil record of cephalopod eggs is scant since their soft, gelatinous eggs decompose quickly and have little chance to fossilize. Another major group of Mesozoic cephalopods, the belemnoids , have no documented eggs in the fossil record whatsoever, although this may be because scientists have not properly searched for them rather than an actual absence from the fossil record. Fossil fish eggs have an extensive record going at least as far back as

250-399: The vertebrae and skull . The outside of the bone consists of a layer of connective tissue called the periosteum . Additionally, the outer shell of the long bone is compact bone , then a deeper layer of cancellous bone (spongy bone) which contains in the medullary cavity the bone marrow . The outer shell of the long bone is made of cortical bone also known as compact bone. This

275-469: The act of raiding a Protoceratops nest. Following the discovery of Troodon eggs in 1990 , their close resemblance to elongatoolithids lead Russian paleontologist Konstantin Mikhailov to believe they were actually theropod eggs, not Protoceratops eggs. In 1994 , his hypothesis was confirmed when Norell et al. discovered embryonic remains of an Oviraptorosaur inside an elongatoolithid egg. It

SECTION 10

#1732787681529

300-584: The early 1990s Russian paleontologist Konstantin Mikhailov brought attention to Zhao's work in the English language scientific literature . Eggs laid by invertebrate animals are known from the fossil record. Among these are eggs laid by ancient cephalopods . Eggs laid by ammonoids are the best known cephalopod egg fossils. The best preserved fossil ammonite eggs were preserved in the Jurassic Kimmeridge Clay of England . Nevertheless,

325-472: The eggs in a bird-like posture, and the parent's body would effectively cover the entire nest. This indicates intensive parental care of the eggs. It is not certain whether the specimens found brooding are male or female, but the examined limb bones of a brooding Citipati show none of the evidence of egg-laying that would be expected if theropods took phosphorus and calcium from long bone tissues (like crocodylians) or medullary bone (like birds), suggesting it

350-409: The eggshells varies from scattered nodes (dispersituberculate) to linear ridges (lineartuberculate), occasionally with nodes in long irregular chains (ramotuberculate). The first elongatoolithid eggs were discovered in the 1920s, and were thought to belong to Protoceratops . Oviraptor was first discovered in 1924 with a nest of elongatoolithid eggs, and it was conjectured to have been caught in

375-415: The load during daily activities and they are crucial for skeletal mobility. They grow primarily by elongation of the diaphysis , with an epiphysis at each end of the growing bone. The ends of epiphyses are covered with hyaline cartilage ("articular cartilage"). The longitudinal growth of long bones is a result of endochondral ossification at the epiphyseal plate . Bone growth in length is stimulated by

400-455: The mammillary layer or the cone layer, is made up of radiating calcite crystals. The outer layer is distinctive for not being divided into well-defined shell units, and hence it is called the continuous layer or the cryptoprismatic layer. The boundary between the two layers is abrupt, but wavy. Typically, elongatoolithid eggs have an angusticanaliculate pore system, meaning the pores are thin, straight, and unbranching. The surface ornamentation of

425-432: The most well known kind of fossil reptile eggs. Fossil eggs are classified according to the parataxonomic system called Veterovata. There are three broad categories in the scheme, on the pattern of organismal phylogenetic classification, called oofamilies, oogenera and oospecies (collectively known as ootaxa). The names of oogenera and oofamilies conventionally contain the root "oolithus" meaning "stone egg", but this rule

450-494: The oogenera Nanhsiungoolithus , Elongatoolithus , Macroolithus , Macroelongatoolithus , Ellipsoolithus , Trachoolithus , Heishanoolithus , Ornitholithus , Paraelongatoolithus , Undulatoolithus , and Rodolphoolithus . Also, Porituberoolithus and Continuoolithus are occasionally included in Elongatoolithidae. Oofamily The first named oospecies was Oolithes bathonicae ,

475-482: The production of growth hormone (GH), a secretion of the anterior lobe of the pituitary gland . The long bone category includes the femora, tibiae, and fibulae of the legs; the humeri , radii , and ulnae of the arms; metacarpals and metatarsals of the hands and feet, the phalanges of the fingers and toes, and the clavicles or collar bones. The long bones of the human leg comprise nearly half of adult height. The other primary skeletal component of height are

500-443: The rest unless otherwise noted: Testudoid Geckonoid Crocodiloid Mosasauroid Dinosauroid-spherulitic Dinosauroid-prismatic Ornithoid Incertae sedis /Unclassified Long bone The long bones are those that are longer than they are wide. They are one of five types of bones : long, short , flat , irregular and sesamoid . Long bones, especially the femur and tibia , are subjected to most of

525-473: The supposed Protoceratops eggs found in Mongolia . In 1975 , Chinese paleontologist Zhao Zikui devised a formal classification system for fossil eggs , in which he created a new oogenus for "Oolithes" elongatus : Elongatoolithus . He classified Elongatoolithus and another new oogenus Macroolithus into a new oofamily, Elongatoolithidae. The oogenus Spongioolithus , first named by Bray in 1999,

SECTION 20

#1732787681529

550-482: The world, leading to the development of multiple competing classification schemes. In 1975 Chinese paleontologist Zhao Zi-Kui started a revolution in fossil egg classification by developing a system of " parataxonomy " based on the traditional Linnaean system to classify eggs based on their physical qualities rather than their hypothesized mothers. Zhao's new method of egg classification was hindered from adoption by Western scientists due to language barriers. However, in

575-542: Was a male. Also, the clutches were proportionally large compared to the size of the adult, which suggests a polygamous system, similar to modern paleognaths , in which multiple females contribute eggs to a single nest which is then cared for by the father. The eggs are laid in pairs, as shown by the discovery of two Macroolithus eggs simultaneously within the mother, and the pairing of eggs within nests. This shows that oviraptorosaurs had two functional oviducts (unlike birds, which have only one), and would produce two eggs at

600-682: Was originally considered a member of Elongatoolithidae, but it is currently considered a junior synonym of the non-elongatoolithid Continuoolithus . Elongatoolithids are known to be the eggs of oviraptorosaurs (except for the avian Ornitholithus ). Several oviraptorosaurs have been found in association with elongatoolithid eggs, including some specimens still inside the mother. Fossil embryos found inside elongatoolithid eggs have also been identified as oviraptorosaurian. Several oviraptorosaurs, like Nemegtia , Citipati , Oviraptor , and cf. Machairasaurus , have been found sitting on top of their nests. All of them have their arms spread out over

625-434: Was then hypothesized that Oviraptor was in fact a brooding mother, not an egg thief. Since then, several discoveries of embryos and association of adults with eggs have shown that elongatoolithids are the eggs of Oviraptorosaurs. The first oospecies formally described was " Oolithes " elongatus (Young, 1954 ), from China . They were thought to belong to Protoceratops or a related dinosaur because of their similarity to

#528471