|
Montanoolithus
''Montanoolithus'' is an oogenus of fossil egg found in Montana and Alberta. They were probably laid by a dromaeosaur or a caenagnathid.D. K. Zelenitsky and F. Therrien. (2008) "Unique maniraptoran egg clutch from the Upper Cretaceous Two Medicine Formation of Montana reveals theropod nesting behaviour." ''Palaeontology'' 51(6):1253–1259 Distribution The type specimen of ''Montanoolithus'' was found in the Two Medicine Formation on the Blackfeet Reservation. Other specimens are known from the Oldman Formation in Alberta. All ''Montanoolithus'' fossils yet discovered date to the Late Cretaceous. Description ''Montanoolithus strongorum'' is known from several eggshell fragments and a partial egg clutch (with five preserved eggs). When complete, this clutch likely had at least twelve eggs, arrayed in pairs in a ring, similar to the Asian oviraptorid clutches. The most complete egg is elongated, measuring long by wide, and slightly asymmetrical. The outer surface of its s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oogenus
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''. History The first named oospecies was '' Oolithes bathonicae'', a name given provisi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egg Fossils
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''. History The first named oospecies was '' Oolithes bathonicae'', a name given provisi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oofamily
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''. History The first named oospecies was '' Oolithes bathonicae'', a name given provisi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Australia and Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladistic Analysis
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived characteristics (synapomorphies'')'' that are not present in more distant groups and ancestors. However, from an empirical perspective, common ancestors are inferences based on a cladistic hypothesis of relationships of taxa whose character states can be observed. Theoretically, a last common ancestor and all its descendants constitute a (minimal) clade. Importantly, all descendants stay in their overarching ancestral clade. For example, if the terms ''worms'' or ''fishes'' were used within a ''strict'' cladistic framework, these terms would include humans. Many of these terms are normally used paraphyletically, outside of cladistics, e.g. as a 'grade', which are fruitless to precisely delineate, especially when including extinct species. Radi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Parataxa Described In 2008
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oviducts
The oviduct in mammals, is the passageway from an ovary. In human females this is more usually known as the Fallopian tube or uterine tube. The eggs travel along the oviduct. These eggs will either be fertilized by spermatozoa to become a zygote, or will degenerate in the body. Normally, these are paired structures, but in birds and some cartilaginous fishes, one or the other side fails to develop (together with the corresponding ovary), and only one functional oviduct can be found. Except in teleosts, the oviduct is not directly in contact with the ovary. Instead, the most anterior portion ends in a funnel-shaped structure called the infundibulum, which collects eggs as they are released by the ovary into the body cavity. The only female vertebrates to lack oviducts are the jawless fishes. In these species, the single fused ovary releases eggs directly into the body cavity. The fish eventually extrudes the eggs through a small genital pore towards the rear of the body. Fis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dromaeosaurs
Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning 'runner', and ('), meaning 'lizard'. In informal usage, they are often called raptors (after ''Velociraptor''), a term popularized by the film ''Jurassic Park''; a few types include the term "raptor" directly in their name and have come to emphasize their bird-like appearance and speculated bird-like behavior. Dromaeosaurid fossils have been found across the globe in North America, Europe, Africa, Asia, South America and Antarctica, with some fossils giving credence to the possibility that they inhabited Australia as well. They first appeared in the mid-Jurassic Period (late Bathonian stage, about 167 million years ago) and survived until the end of the Cretaceous (Maastrichtian stage, 66 ma), existing until the Cretaceous–Paleogene ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troodon
''Troodon'' ( ; ''Troödon'' in older sources) is a wastebasket taxon and a dubious genus of relatively small, bird-like dinosaurs known definitively from the Campanian age of the Late Cretaceous period (about 77 mya). It includes at least one species, ''Troodon formosus'', known from Montana. Discovered in October 1855, ''T. formosus'' was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877. Several well-known troodontid specimens from the Dinosaur Park Formation in Alberta were once believed to be members of this genus. However, recent analyses in 2017 have found the genus to be undiagnostic and referred some of these specimens to the genus ''Stenonychosaurus'' (long believed to be synonymous with ''Troodon'') and others to the genus ''Latenivenatrix''. The genus name is Ancient Greek for "wounding tooth", referring to the teeth, which were different from those of most other theropods known at the time of their discovery. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oviraptorids
Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptoran dinosaurs. Oviraptorids are characterized by their toothless, parrot-like beaks and, in some cases, elaborate crests. They were generally small, measuring between one and two metres long in most cases, though some possible oviraptorids were enormous. Oviraptorids are currently known only from the Late Cretaceous of Asia, with the most well-known species and complete specimens found only in the Gobi Desert of Mongolia and northwestern China. Description The most characteristic feature of this group is the skull structure. Oviraptorids had short snouts and very deep mandibles. Some taxa (such as ''Citipati'', ''Corythoraptor'', ''Rinchenia'') had a midline crest on top of the skull, resembling that of a cassowary. Other distinguishing characteristics include a bony spike intruding on the mandibular fenestra, nostrils placed very high and far back on the snout, an extremely thin bony bar beneath the ey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troodontids
Troodontidae is a clade of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discoveries of complete and articulated specimens (including specimens which preserve feathers, eggs, embryos, and complete juveniles), have helped to increase understanding about this group. Anatomical studies, particularly studies of the most primitive troodontids, like ''Sinovenator'', demonstrate striking anatomical similarities with ''Archaeopteryx'' and primitive dromaeosaurids, and demonstrate that they are relatives comprising a clade called Paraves. Description Troodontids are a group of small, bird-like, gracile maniraptorans. All troodontids have unique features of the skull, such as large numbers of closely spaced teeth in the lower jaw. Troodontids have sickle-claws and raptorial hands, and some of the highest non-avian encephaliza ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maniraptoran
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. ''Ornitholestes'' and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria, Maniraptora comprises the more inclusive clade Maniraptoriformes. Maniraptorans first appear in the fossil record during the Jurassic Period (see ''Eshanosaurus''), and survive today as living birds. Description Maniraptorans are characterized by long arms and three-fingered hands (though reduced or fused in some lineages), as well as a "half-moon shaped" (semi-lunate) bone in the wrist (carpus). In 2004, Tom Holtz and Halszka Osmólska pointed out six other maniraptoran characters relating to specific details of the skeleton. Unlike most other saurischian dinosaurs, which have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Egg Fossils")
