Chondrichthyes is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or bony fish, which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opercula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates.
Mammoth Cave National Park is a national park of the United States in south-central Kentucky. It encompasses portions of Mammoth Cave, the longest known cave system in the world. The park's 52,830 acres (21,380 ha) are located primarily in Edmonson County, with small areas extending eastward into Hart and Barren counties. The Green River runs through the park, with a tributary called the Nolin River feeding into the Green just inside the park.
The Pennyroyal Plateau or Pennyroyal Region, often spelled Pennyrile, is a large physiographic region of Kentucky that features rolling hills, caves, and karst topography in general. It is named for Hedeoma pulegioides, a wild mint that grows in the area. It is also called the "Mississippian Plateau," for the Mississippian geologic age in which it was formed.
The Green River is a 384-mile-long (618 km) tributary of the Ohio River that rises in Lincoln County in south central Kentucky. Tributaries of the Green River include the Barren River, the Nolin River, the Pond River and the Rough River. The river was named after Nathanael Greene, a general of the American Revolutionary War.
Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.
The Kentucky cave shrimp is an eyeless, troglobite shrimp. It lives in caves in Barren County, Edmonson County, Hart County and Warren County, Kentucky. The shrimp's shell has no pigment; the species is nearly transparent and closely resembles its nearest relative, the Alabama cave shrimp.
Glikmanius is an extinct genus of ctenacanth cartilaginous fish which lived in the Carboniferous of North America and Russia. Skeletal remains attributed to the genus are known from Nebraska, USA. Glikmanius is named in honour of the Russian palaeontologist, Dr. Leonid Glikman, who studied the genus and was "the first to propose its ctenacanthiform affinity". G. careforum may have reached lengths of 3 metres (9.8 ft), while G. occidentalis may have reached lengths of over 6 metres (20 ft), making it one the largest marine predators of its time.
Squaloraja is an extinct genus of ray-like marine chimaeriform fish from the Early Jurassic of Europe.
Paleontology in Michigan refers to paleontological research occurring within or conducted by people from the U.S. state of Michigan. During the Precambrian, the Upper Peninsula was home to filamentous algae. The remains it left behind are among the oldest known fossils in the world. During the early part of the Paleozoic Michigan was covered by a shallow tropical sea which was home to a rich invertebrate fauna including brachiopods, corals, crinoids, and trilobites. Primitive armored fishes and sharks were also present. Swamps covered the state during the Carboniferous. There are little to no sedimentary deposits in the state for an interval spanning from the Permian to the end of the Neogene. Deposition resumed as glaciers transformed the state's landscape during the Pleistocene. Michigan was home to large mammals like mammoths and mastodons at that time. The Holocene American mastodon, Mammut americanum, is the Michigan state fossil. The Petoskey stone, which is made of fossil coral, is the state stone of Michigan.
Paleontology in Kentucky refers to paleontological research occurring within or conducted by people from the U.S. state of Kentucky.
Paleontology in Virginia refers to paleontological research occurring within or conducted by people from the U.S. state of Virginia. The geologic column in Virginia spans from the Cambrian to the Quaternary. During the early part of the Paleozoic, Virginia was covered by a warm shallow sea. This sea would come to be inhabited by creatures like brachiopods, bryozoans, corals, and nautiloids. The state was briefly out of the sea during the Ordovician, but by the Silurian it was once again submerged. During this second period of inundation the state was home to brachiopods, trilobites and entire reef systems. During the mid-to-late Carboniferous the state gradually became a swampy environment.
Paleontology in Iowa refers to paleontological research occurring within or conducted by people from the U.S. state of Iowa. The paleozoic fossil record of Iowa spans from the Cambrian to Mississippian. During the early Paleozoic Iowa was covered by a shallow sea that would later be home to creatures like brachiopods, bryozoans, cephalopods, corals, fishes, and trilobites. Later in the Paleozoic, this sea left the state, but a new one covered Iowa during the early Mesozoic. As this sea began to withdraw a new subtropical coastal plain environment which was home to duck-billed dinosaurs spread across the state. Later this plain was submerged by the rise of the Western Interior Seaway, where plesiosaurs lived. The early Cenozoic is missing from the local rock record, but during the Ice Age evidence indicates that glaciers entered the state, which was home to mammoths and mastodons.
Cladodus is an extinct genus of cartilaginous fishes in the family Ctenacanthidae. As the name implies, they are a type of cladodont, primitive sharks with teeth designed to snag fish and swallow them whole, instead of sawing off chunks to swallow.
Kaibabvenator swiftae is a very large, extinct ctenacanthiform fish that lived in marine environments in what is now Arizona, during the Middle Permian Period. K. swiftae is known from large teeth up to 30 millimeters long found in the Kachina Microsite, of the lower Fossil Mountain Member, in the Kaibab Formation near Flagstaff, Arizona, suggesting a total body length of around 5–6 metres (16–20 ft). The specific name honors researcher Sandra Swift for her paleontological contributions to Northern Arizona University.
Helodus is an extinct genus of cartilaginous fish from the Upper Devonian through Lower Permian. While the type species, H. simplex is known from an articulated specimen, the rest of the species in this genus are known entirely from isolated teeth. Over twenty species have been attributed to this genus, many of which may be anterior teeth of other cartilaginous fish. This makes Helodus a wastebasket taxon. For this reason, only the type species can be confidently attributed to this genus until articulated remains of other species are found. H. simplex was around 30 centimeters long.
Ctenacanthiformes is an extinct order of cartilaginous fish. They possessed ornamented fin spines at the front of their dorsal fins and cladodont-type dentition, that is typically of a grasping morphology, though some taxa developed cutting and gouging tooth morphologies. Some ctenacanths are thought to have reached sizes comparable to the great white shark, with body lengths of up to 7 metres (23 ft) and weights of 1,500–2,500 kilograms (3,300–5,500 lb), while others reached lengths of only 30 centimetres (12 in). The earliest ctenacanths appeared during the Frasnian stage of the Late Devonian, with the group reaching their greatest diversity during the Early Carboniferous (Mississippian), and continued to exist into at least the Middle Permian (Guadalupian). Some authors have suggested members of the family Ctenacanthidae may have survived into the Cretaceous based on teeth found in deep water deposits of Valanginian age in France and Austria, however, other authors contend that the similarity of these teeth to Paleozoic ctenacanths is only superficial, and they likely belong to neoselachians instead.
Dracopristis is an extinct genus of ctenacanth that lived around 307 million years ago during the Pennsylvanian subperiod of the Carboniferous period. A single species is known, Dracopristis hoffmanorum, which is named in honor of Ralph and Jeanette Hoffman.
Saivodus is an extinct genus of ctenacanthiform fish that existed in early Mississippian of the Carboniferous period. Fossils have been found in Ireland, Scotland, England, Belgium, Morocco, and the United States. Teeth assigned to that genus are also known from the Permian (Leonardian) Kaibab Formation.
Strigilodus is an extinct genus of cartilaginous fish within the order Petalodontiformes. This genus existed during the Lower Carboniferous period, approximately 350 million years ago.
Cosmoselachus is an extinct genus of symmoriiform chondrichthyan from the Upper Carboniferous aged Fayetteville Shale of Arkansas, United States. The genus contains a single species, C. mehlingi, which is known from a partial specimen that includes the cranium, jaws, gill arches, pectoral fins, and teeth.
