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Melovatskaya Formation
The Melovatka or Melovatsskaya Formation is a Cenomanian geologic formation in Russia. Pterosaur fossils have been recovered from the formation. Description The two phosphorite horizons are separated in places by a yellowish sand interbed up to 1 m thick; however, they sometimes merge into a single horizon. The lower interbed or part of the integrated phosphorite horizon shows in places straight diagonal bedding, which is manifested in the orientation of almost flat pellets, pebbles, and pseudomorphs on bivalve shells. The phosphate concretions are irregular aggregates and rounded pebbles, ranging in size from several millimeters to 5–10 cm. They are dark brown or nearly black. Fossil content The following vertebrate fossils were reported from the formation:Melovatka 3 at |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraorthacodus
''Paraorthacodus'' is an extinct genus of cartilaginous fish. An unidentified species has been found in the Hasle Formation of Bornholm Bornholm () is a Danish island in the Baltic Sea, to the east of the rest of Denmark, south of Sweden, northeast of Germany and north of Poland. Strategically located, Bornholm has been fought over for centuries. It has usually been ruled by ..., Denmark. References Jurassic sharks Prehistoric shark genera Palaeospinacidae Fossils of Denmark Hasle Formation {{paleo-shark-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteichthyes
Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilage. The vast majority of fish are members of Osteichthyes, which is an extremely diverse and abundant group consisting of 45 orders, and over 435 families and 28,000 species. It is the largest class of vertebrates in existence today. The group Osteichthyes is divided into the ray-finned fish (Actinopterygii) and lobe-finned fish (Sarcopterygii). The oldest known fossils of bony fish are about 425 million years old, which are also transitional fossils, showing a tooth pattern that is in between the tooth rows of sharks and bony fishes. Osteichthyes can be compared to Euteleostomi. In paleontology the terms are synonymous. In ichthyology the difference is that Euteleostomi presents a cladistic view which includes the terrestrial tetrap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ornithocheiroidea
Ornithocheiroidea (or ornithocheiroids) is a group of pterosaurs within the extinct suborder Pterodactyloidea. They were typically large pterosaurs that lived from the Early to Late Cretaceous periods (Valanginian to Maastrichtian stages), with fossil remains found all over the world except Antarctica. Ornithocheiroids were the most advanced group of pterosaurs, as the group includes the clade Azhdarchoidea, of which its members lived until the Maastrichtian stage of the Late Cretaceous, around 66 million years ago. Notable pterosaurs from this group include the pteranodontians ''Pteranodon'' and ''Nyctosaurus'', the ornithocheirid ''Ornithocheirus'', the anhanguerid ''Tropeognathus'', as well as the azhdarchids ''Hatzegopteryx'' and ''Quetzalcoatlus''. Classification The name Ornithocheiroidea was originally defined as an apomorphy-based taxon by Christopher Bennett in 1994. It was given a relationship-based definition in 2003 by Alexander Kellner, who defined it as the least in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elasmosauridae
Elasmosauridae is an extinct family of plesiosaurs, often called elasmosaurs. They had the longest necks of the plesiosaurs and existed from the Hauterivian to the Maastrichtian stages of the Cretaceous, and represented one of the two groups of plesiosaurs present at the end of the Cretaceous alongside Polycotylidae. Their diet mainly consisted of crustaceans and molluscs. Description The earliest elasmosaurids were mid-sized, about . In the Late Cretaceous, elasmosaurids grew as large as , such as '' Styxosaurus'', ''Albertonectes'', and '' Thalassomedon''. Their necks were the longest of all the plesiosaurs, with anywhere between 32 and 76 (''Albertonectes'') cervical vertebrae. They weighed up to several tons. Classification Early three-family classification Though Cope had originally recognized ''Elasmosaurus'' as a plesiosaur, in an 1869 paper he placed it, with ''Cimoliasaurus'' and ''Crymocetus'', in a new order of sauropterygian reptiles. He named the group Streptos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chimaeridae
The Chimaeridae, or short-nosed chimaeras, are a family of cartilaginous fish. They resemble other chimaeras in general form and habits, but have short, rounded snouts, without the modifications found in related families. Many species have long, tapering tails, giving them an alternative name of ratfish. Shortnose chimaeras have a venomous spine on their backs, which is sufficiently dangerous to injure humans. They are found in temperate and tropical marine waters worldwide. Most species are restricted to depths below , but a few, notably the spotted ratfish and rabbit fish, can locally be found at relatively shallow depths. They range from in maximum total length, depending on species. Species The species are grouped into two genera and include: Family Chimaeridae * Genus ''Chimaera'' Linnaeus, 1758 ** '' Chimaera argiloba'' Last, W. T. White & Pogonoski, 2008 (whitefin chimaera) ** '' Chimaera bahamaensis'' Kemper, Ebert, Didier & Compagno, 2010 (Bahamas ghostshark ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelonioidea
Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, Kemp's ridley, and olive ridley sea turtles. All six of the sea turtle species present in US waters (all of those listed above except the flatback) are listed as endangered and/or threatened under the Endangered Species Act. The seventh sea turtle species is the flatback, which exists in the waters of Australia, Papua New Guinea and Indonesia. Sea turtles can be separated into the categories of hard-shelled (cheloniid) and leathery-shelled ( dermochelyid).Wyneken, J. 2001. The Anatomy of Sea Turtles. U.S Department of Commerce NOAA Technical Memorandum NMFS-SEFSC-470, 1-172 pp. There is only one dermochelyid species which is the leatherback sea turtle. Description For each of the seven types of sea turtles, females and males are the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platypterygius
''Platypterygius'' is a historically paraphyletic genus of platypterygiine ichthyosaur from the Cretaceous period. It was historically used as a wastebasket taxon, and most species within ''Platypterygius'' likely are undiagnostic at the genus or species level, or represent distinct genera, even being argued as invalid. While fossils referred to ''Platypterygius'' have been found throughout different continents, the holotype specimen was found in Germany. Description As ''Platypterygius'' contains multiple species not especially close to each other, little can be said in terms of shared characteristics. According to an analysis by Fischer (2012), all anatomical features used to unify ''Platypterygius'' species are either not actually present in each species, or much more widespread among unrelated ophthalmosaurs. Generally, species referred to this genus were large bodied macropredators based on their robust dentition. This is also supported by ''P. australis'' having been foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Odontaspis
''Odontaspis'' (from el, ὀδούς 'tooth') and el, ἀσπίς 'shield') is a genus of sand shark with two extant species. Description Bigeye sand tigers can reach a length of about and smalltooth sand tigers of about 4.1 m. They are large-bodied sharks with long, conical snouts, broad-based dorsal and anal fins, and an asymmetrical caudal fin with a strong lower lobe. Their teeth are large, with prominent narrow cusps. They are distinguished from the similar genus '' Carcharias'' by the absence of crushing posterior teeth.Bourdon, J''Odontaspis'' Agassiz 1838 ''Elasmo.com''. Retrieved on December 24, 2008. These bottom dwelling, deepwater sharks can be found in temperate and tropical waters of all the oceans. Extant species * '' Odontaspis ferox'' ( A. Risso, 1810) (smalltooth sand tiger) * ''Odontaspis noronhai'' (Maul, 1955) (bigeye sand tiger) Extinct species Extinct species within this genus include: * ''Odontaspis aculeatus'' Capetta & Case, 1975 * ''O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
