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Jewett Sand Formation
The Jewett Sand Formation is a geologic formation in California, USA. It preserves fossils dating back to the Miocene Epoch of the Neogene period. Vertebrates Cartilaginous fishes Sharks 200px, Fossil teeth of ''C. hastalis'' *''† Alopias exigua''F. M. Anderson. 1911. The Neocene deposits of Kern River, California, and the Temblor Basin. Proceedings of the California Academy of Sciences. 3:73-148 *''† Alopias latidens'' *''Alopias vulpinus *''† Carcharocles angustidens *''†Carcharodon hastalis *''Carcharhinus sp. *''Cephaloscyllium sp. *''Cetorhinus sp. *'' Echinorhinus blakei *''† Galeocerdo medius *''† Galeorhinus latus *'' Heterodontus sp.'' *''Hexanchus sp.'' *''†Megachasma applegatei'' K. Shimada, B. J. Welton, and D. J. Long. 2014. A new fossil megamouth shark (Lamniformes, Megachasmidae) from the Oligocene-Miocene of the western United States. Journal of Vertebrate Paleontology. 34(2):281-290 *''†Megalolamna paradoxodon'' *''† Negaprion elongata *''Od ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation (stratigraphy)
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 (geology), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinorhinus
''Echinorhinus'' is the only extant genus in the family Echinorhinidae. Taxonomy Echinorhinidae are traditionally classified in the order Squaliformes, together with kitefin and gulper sharks.Compagno, 2005. "Sharks of the World". However, a phylogenetic estimate based on gene capture data and mitochondrial data suggests that they are not squaliform sharks, but may be more likely to be appropriately classed in their own group, as a sister group to angel sharks and sawsharks. Phylogenetic placement of Echinorhinidae has been ambiguous in morphological and molecular studies, either being included within Squaliformes, considered sister to Squaliformes, or placed in a separate group with Sawsharks (Pristiophoriformes) or angel sharks (Squatiniformes). For this reason they are sometimes given their own order, Echinorhiniformes. Etymology The name is from Greek ''echinos'' meaning "spiny" and ''rhinos'' meaning "nose". Species * ''Echinorhinus brucus'' Bonnaterre, 1788 (brambl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bat Ray In Kelp Forest, San Clemente Island, Channel Islands, California
Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most birds, flying with their very long spread-out digits covered with a thin membrane or patagium. The smallest bat, and arguably the smallest extant mammal, is Kitti's hog-nosed bat, which is in length, across the wings and in mass. The largest bats are the flying foxes, with the giant golden-crowned flying fox, ''Acerodon jubatus'', reaching a weight of and having a wingspan of . The second largest order of mammals after rodents, bats comprise about 20% of all classified mammal species worldwide, with over 1,400 species. These were traditionally divided into two suborders: the largely fruit-eating megabats, and the echolocating microbats. But more recent evidence has supported dividing the order into Yinpterochiroptera and Yangochir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squalus
''Squalus'' is a genus of dogfish sharks in the family Squalidae. Commonly known as spurdogs, these sharks are characterized by smooth dorsal fin spines, teeth in upper and lower jaws similar in size, caudal peduncle with lateral keels; upper precaudal pit usually present, and caudal fin without subterminal notch. In spurdogs, the hyomandibula (the bone connecting the braincase to the jaws) is oriented at a right angle to the neurocranium, while in other sharks, the hyomandibula runs more parallel to the body. This led some to think that the upper jaw of ''Squalus'' would not be as protractile as the jaws of other sharks. However, a study that compared different jaw suspension types in sharks showed that this is not the case and that ''Squalus'' is quite capable of protruding its upper jaw during feeding.Wilga, C.D., Motta, P.J. & Sanford, C.P. (2007): Evolution and ecology of feeding in elasmobranchs. ''Integrative and Comparative Biology, 47 (1): 55-69.'' The name comes from '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sphyrna
''Sphyrna'' (from the Greek word σφῦρα, "hammer") is a genus of hammerhead sharks with a cosmopolitan distribution in the world's oceans. Members of ''Sphyrna'' have a tendency to inhabit coastal waters along the intertidal zone rather than the open ocean, as their prey such as invertebrates, fish, rays, small crustaceans, and other benthic organisms hide in the sands and sediment along these zones. Members of ''Sphyrna'' are also known by synonyms such as ''Zygaena'', ''Cestracion'', and ''Sphyrichthys''. The earliest species described of this genus was ''Sphyrna zygaena'' by Carl Linnaeus in 1758, while the latest described member, '' Sphyrna gilberti'', was discovered and described in 2013. Species The recognized species in this genus are:Martin, R. Aidan. (February 24, 1998)Recent Changes in Hammerhead Taxonomy ''ReefQuest Centre for Shark Research''. Retrieved on October 18, 2008. ;Extant * '' Sphyrna corona'' ( S. Springer, 1940) (scalloped bonnethead) * '' Sphyrn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parotodus
''Parotodus'', commonly known as the false-toothed mako shark (or false mako shark), is an extinct genus of mackerel shark that lived approximately 53 to one million years ago during the Eocene and Pleistocene epochs. Its teeth, which are found worldwide, are often prized by fossil collectors due to their rarity. The scarcity of fossils is because ''Parotodus'' likely primarily inhabited open oceans far away from the continents. Description Initially appearing as a small shark, ''Parotodus'' gradually increased in size over geologic time and by the Neogene period became one of the largest sharks of its time. A 1999 study estimated the genus to have measured up to in length. The teeth of ''Parotodus'' are distinctively curved and rarely show feeding damage, which suggests that it mainly preyed on soft-bodied animals. Paleontologists speculate that this included other sharks, including the contemporaneous Megalodon. Classification Due to the general scarcity and ambiguity of foss ... [...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] |
Negaprion
''Negaprion'' is a genus of requiem sharks in the family Carcharhinidae. It contains the two extant species of lemon sharks: the lemon shark (''N. brevirostris'') of the Americas, and the sicklefin lemon shark (''N. acutidens'') of the Indo-Pacific. Both species are large, slow-moving, bulky sharks inhabiting shallow coastal waters, and can be identified by their short, blunt snouts, two dorsal fins of nearly equal size, and uniform yellowish brown or gray coloration. Species * '' Negaprion acutidens'' ( Rüppell, 1837) (sicklefin lemon shark) * '' Negaprion brevirostris'' ( Poey, 1868) (lemon shark) * †'' Negaprion eurybathrodon'' (Blake, 1862) See also * List of prehistoric cartilaginous fish genera This list of prehistoric cartilaginous fish genera is an attempt to create a comprehensive listing of all genera that have ever been included in the class chondrichthyes ''and'' are known from the fossil record. This list excludes purely vernacul ... References {{Authorit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megalolamna Paradoxodon
''Megalolamna'' is an extinct genus of lamniform shark that belongs to the family Otodontidae. Its name comes from the similarity of its teeth to those of the extant shark genus '' Lamna.'' It is known from the early Miocene Chilcatay Formation of Peru, Oi and O'oshimojo Formations of Japan, and the Jewett Sand Formation of California and Pungo River Formation, North Carolina in the United States, implying a cosmopolitan distribution. The largest specimen is estimated to have measured about long. Taxonomy It is considered to be the sister genus of '' Otodus''. The study of ''Megalolamna'''s taxonomic relationships also demonstrates the possibility that ''Otodus'' needs to include the species sometimes assigned to ''Carcharocles'' (i.e., the megatoothed lineage, including megalodon) in order to be monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megachasma
''Megachasma'' is a genus of sharks. It is usually considered to be the sole genus in the distinct family Megachasmidae, though suggestion has been made that it may belong in the family Cetorhinidae, of which the basking shark is currently the sole extant member. ''Megachasma'' is known from a single living species, ''Megachasma pelagios''. In addition to the living ''M. pelagios'', however, two extinct megamouth species – the Priabonian '' M. alisonae''Shimada, Kenshu, and David J. Ward. "The oldest fossil record of the megamouth shark from the late Eocene of Denmark, and comments on the enigmatic megachasmid origin./ref> and the Oligocene–Miocene '' M. applegatei'' – have also recently been proposed on the basis of fossilized tooth remains. An early ancestor of the recent species ''Megachasma pelagios'' was reported from the early Miocene (Burdigalian) of Belgium. However, the Cretaceous-aged ''M. comanchensis'' has been recently reclassified as an odontas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexanchus
The sixgill sharks are a genus, ''Hexanchus'', of deepwater sharks in the family Hexanchidae. These sharks are characterized by a broad, pointed head, six pairs of gill slits, comb-like, yellow lower teeth, and a long tail. The largest species can grow up to 8 m long and weigh over 600 kg (1320 lb). They are continental shelf-dwelling and abyssal plain scavengers with a keen sense of smell and are among the first to arrive at carrion, together with hagfish and rattails. They show a characteristic rolling motion of the head when feeding. They have been found at depths of up to . Though only two extant species (the bluntnose sixgill shark and the bigeyed sixgill shark) were originally known, a third, the Atlantic sixgill shark, was found to exist. Swimming behavior The bluntnose sixgill shark, ''Hexanchus griseus'', is relatively common to scientists. However, very little information exists about its distribution patterns, migrations and behavior. Data on occurrence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
