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Sclerorhynchiformes
Sclerorhynchoidei is an extinct suborder of rajiform rays that had long rostra with large denticles similar to sawfishes and sawsharks. This feature was convergently evolved, recently proposed as 'pristification', and their closest living relatives are actually skates. While they are often called "sawfishes", sawskates is a more accurate common name proposed in 2021 for sclerorhynchoids, which has been subsequently used by other researchers. The suborder contains five named families: Ganopristidae, Ischyrhizidae, Onchopristidae, Ptychotrygonidae, and Schizorhizidae. Several genera (see below) are not currently placed in any of these families. Sclerorhynchoids first appeared in the Barremian and went extinct during the Cretaceous–Paleogene extinction event, with former Paleocene occurrences being misidentifications or reworked specimens. One female specimen of '' Libanopristis'' with nine embryos preserved ''in situ'' represents one of the first fossil evidence of b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rajiformes
Rajiformes is one of the four Order (biology), orders in the clade Batomorphi, often referred to as the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion diagnostic to this taxon is known as Batoid locomotion, rajiform locomotion. The eyes and Spiracle (vertebrates), spiracles are located on the upper surface of the head and the gill slits are on the underside of the body. Most species give birth to live young, although some lay eggs enclosed in a horny capsule ("mermaid's purse"). Characteristics Rajoids typically have a dorsoventrally flattened body. The snout is slender and pointed and the wide mouth, often covered with a fleshy nasal flap, is on the underside of the head. The eyes and well-developed spiracles are located on the top of the head. In most spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asflapristis
''Asflapristis'' is an extinct genus of ptychotrygonid sclerorhynchoid that lived during the Late Cretaceous. It contains two valid species: ''A. cristadentis'' from the Akrabou Formation of Morocco and ''A. rugosa'' from the Eutaw Formation of Georgia and Mississippi and the Pleasant Creek Formation of North Carolina. Articulated skeletons of ''A. cristadentis'' show it had secondarily lost the rostral Rostral may refer to: Anatomy * Rostral (anatomical term), situated toward the oral or nasal region * Rostral bone, in ceratopsian dinosaurs * Rostral organ, of certain fish * Rostral scale The rostral scale, or rostral, in snakes and other sca ... denticles typical of sclerorhynchoids, a process called "depristification". References {{Taxonbar, from=Q131316176 Sclerorhynchoidei Prehistoric cartilaginous fish genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barremian
The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded by the Hauterivian and followed by the Aptian Stage.See Gradstein ''et al.'' (2004) or the online geowhen database (link below) Stratigraphic definitions The original type locality for the Barremian Stage is in the vicinity of the village of Barrême, Alpes-de-Haute-Provence, France. Henri Coquand defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the ammonites '' Spitidiscus hugii'' and ''Spitidiscus vandeckii''. The end of the Barremian is determined by the geomagnetic reversal at the start of the M0r chronozone, which is biologically near the first appearance of the ammonite '' Paradesh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is Cladogram#Homoplasies, homoplasy. The recurrent evolution of flight is a classic example, as flying pterygota, insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''homology (biology), homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different trai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micropristis
''Micropristis'' is an extinct genus of ganopristid sclerorhynchoid that lived in the Middle East and Europe during the Late Cretaceous. The type specimen is known from the Cenomanian of Lebanon, and other specimens referrable to this genus have been found in Santonian-Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ... age rocks of Europe. References Cretaceous cartilaginous fish Cretaceous fish of Europe Prehistoric cartilaginous fish genera {{paleo-rajiformes-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptychotrygon
''Ptychotrygon'' is a genus of sawfish-like ray whose fossils have been found worldwide from the Cretaceous period (Albian-Maastrichtian). Along with '' Ptychotrygonoides'', '' Texatrygon'', and ''Asflapristis'', it is the member of the family Ptychotrygonidae within the suborder Sclerorhynchoidei Sclerorhynchoidei is an extinct suborder of Rajiformes, rajiform Batoidea, rays that had long Rostrum (anatomy)#Vertebrates, rostra with large Fish scale#Placoid scales, denticles similar to Sawfish, sawfishes and Sawshark, sawsharks. This featu .... Species The following species are considered valid: * †''Ptychotrygon ameghinorum'' * †''Ptychotrygon blainensis'' * †''Ptychotrygon eutawensis'' * †''Ptychotrygon geyeri'' * †''Ptychotrygon mcnultyi'' * †''Ptychotrygon nazeensis'' * †''Ptychotrygon pustulata'' * †''Ptychotrygon rostrispatula'' * †''Ptychotrygon striata'' * †''Ptychotrygon triangularis'' * †''Ptychotrygon vermiculata'' References Prehisto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schizorhiza
''Schizorhiza'' is an extinct genus of schizorhizid sclerorhynchoid that lived during the Late Cretaceous. It contains one valid species, ''Schizorhiza stromeri''. It lived from the Campanian to Maastrichtian, and its fossils have been found in Africa, the Middle East, North America, and South America. Taxonomy ''Schizorhiza stromeri'' was named by Wilhelm Weiler in 1930 for rostral denticles from the Nubian Sandstone of Egypt. The species was named in honor of Ernst Stromer. A second species, ''S. weileri'', was named by Giselda Serra in 1933 for rostral denticles from Libya. It is considered a junior synonym of ''S. stromeri''. Description ''Schizorhiza'' is characterized by its robust rostrum with over 1,800 denticles arranged in dense batteries, which form a continuous cutting edge along each side. Each denticle was replaced by a series of smaller denticles nested inside its roots and new rows of denticles grew from the end of the rostrum. Among sclerorhynchoids, this d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovoviviparity
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop inside eggs that remain in the mother's body until they are ready to hatch. The young of some ovoviviparous amphibians, such as '' Limnonectes larvaepartus'', are born as larvae, and undergo further metamorphosis outside the body of the mother. Members of genera '' Nectophrynoides'' and '' Eleutherodactylus'' bear froglets, not only the hatching, but all the most conspicuous metamorphosis, being completed inside the body of the mother before birth. Among insects that depend on opportunistic exploitation of transient food sources, such as many Sarcophagidae and other carrion flies, and species such as many Calliphoridae, that rely on fresh dung, and parasitoids such as tachinid flies that depend on entering the host as soon as possible, the embryos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Libanopristis
''Libanopristis'' is an extinct genus of ganopristid sclerorhynchoid that lived in Lebanon during the Late Cretaceous. One female specimen with nine embryos preserved ''in situ'' represents one of the first fossil evidence of batoid ovoviviparity Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop inside eggs that r .... References Monotypic prehistoric cartilaginous fish genera Fossil taxa described in 1903 {{paleo-rajiformes-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
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''. Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give a good understanding of the pattern of diversification of life on Earth. In addition, the record can predict and fill gaps such as the discovery of '' Tiktaalik'' in the arctic of Canada. Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are sometimes considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. Early edition, published online before prin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleocene
The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name is a combination of the Ancient Greek ''palaiós'' meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event, brought on by an asteroid impact (Chicxulub impact) and possibly volcanism (Deccan Traps), marked the beginning of the Paleocene and killed off 75% of species, most famously the non-avian dinosaurs. The end of the epoch was marked by the Paleocene–Eocene Thermal Maximum (PETM), which was a major climatic event wherein about 2,500–4,500 gigatons of carbon were released into the atmosphere and ocean systems, causing a spike in global temperatures and ocean acidification. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
