Bear Gulch LimestoneThe Bear Gulch Limestone is a limestone-rich geological lens in central Montana, renowned for the quality of its marine fossils from the late Mississippian subperiod, about 324 million years ago. It is exposed over a number of outcrops northeast of the Big Snowy Mountains, and is often considered a component of the more widespread Heath Formation.
HolocephaliGroup of cartilaginous fishHolocephali (sometimes spelled Holocephala; Greek for "complete head" in reference to the fusion of upper jaw with the skull) is a subclass of cartilaginous fish. The only living holocephalans are the three families of chimaeras, but the group also includes many extinct members and was more diverse during the Paleozoic and Mesozoiceras.
St. Louis LimestoneThe St. Louis Limestone is a large geologic formation covering a wide area of the midwest of the United States. It is named after an exposure at St. Louis, Missouri. It consists of sedimentary limestone with scattered chert beds, including the heavily chertified in the . It is exposed at the surface through western Kentucky and Middle Tennessee, including the city of Clarksville, Tennessee.
FalcatidaeFalcatidae is a family of Paleozoic cartilaginous fish belonging to the order Symmoriiformes. Members of this family include Falcatus, a small fish from the Bear Gulch Limestone of Montana. The family first appeared around the start of the Carboniferous, and there is some evidence that they survived well into the early Cretaceous, though its putative Cretaceous members were also argued to be more likely neoselachians.
MontanaMontana ( mon-TAN-ə) is a landlocked state in the Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, and the Canadian provinces of Alberta, British Columbia, and Saskatchewan to the north. It is the fourth-largest state by area, but the eighth-least populous state and the third-least densely populated state.
CladodontCladodont (from Latin cladus, meaning branch and Greek odon, meaning tooth) is the term for a common category of early Devonian shark known primarily for its "multi-cusped" tooth consisting of one long blade surrounded by many short, fork-like tines, designed to catch food that was swallowed whole, instead of being used to saw off chunks of meat like many modern sharks. The group may be treated as the superorder Cladodontomorphi.
Pygmy lanternsharkThe pygmy lanternshark (Etmopterus fusus) is a shark of the family Etmopteridae found in the eastern Indian Ocean from northern Western Australia and possibly Java, at depths of between 430 and 550 m. Its length is up to 26 cm. Reproduction is ovoviviparous.
Sexual dimorphismSex-specific adaptationsMandarin ducks, male (left) and female (right) depicts the male having more color vibrancy compared to his female counterpart, illustrating the dramatic difference in plumage between them, a manifestation of sexual dimorphismSexual dimorphism is the condition where different sexes of the same species exhibit different morphological characteristics, including characteristics not directly involved in reproduction.
SymmoriiformesSymmoriiformes is an extinct order of cartilaginous fish. Originally named Symmoriida by Zangerl (1981), the name has since been corrected to Symmoriiformes to avoid confusion with a family. The symmoriiform fossils record begins during the late Devonian, and most had become extinct by the start of the Permian, with the genus Dwykaselachus from the Artinskian-Kungurian of South Africa being the latest known uncontroversial occurrence.
CarboniferousFifth period of the Paleozoic EraSubdivision of the Carboniferous according to the ICS, as of 2024.Vertical axis scale: Millions of years agoEtymologyName formalityFormalNickname(s)Age of Amphibians or ReptilesUsage informationCelestial bodyEarthRegional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitPeriodStratigraphic unitSystemFirst proposed byWilliam Daniel Conybeare and William Phillips, 1822Time span formalityFormalLower boundary definitionFAD of the ConodontSiphonodella sulcata (discovered to have biostratigraphic issues as of 2006)Lower boundary GSSPLa Serre, Montagne Noire, France43°33′20″N3°21′26″E / 43.5555°N 3.3573°E / 43.5555; 3.3573Lower GSSP ratified1990Upper boundary definitionFAD of the ConodontStreptognathodus isolatus within the morphotypeStreptognathodus wabaunsensis chronoclineUpper boundary GSSPAidaralash, Ural Mountains, Kazakhstan50°14′45″N57°53′29″E / 50.2458°N 57.8914°E / 50.2458; 57.8914Upper GSSP ratified1996Atmospheric and climatic dataSea level above present dayFalling from 120 m to present-day level throughout the Mississippian, then rising steadily to about 80 m at end of periodThe Carboniferous ( ) is a geologic period and system of the Paleozoicera that spans 60 million years, from the end of the Devonian Period 358.86 Ma (million years ago) to the beginning of the Permian Period, 298.9 Ma.
ChondrichthyesChondrichthyes (; from Ancient Greek (khóndros)'cartilage' and (ikhthús)'fish') 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 aquaticvertebrates with paired fins, paired nares, placoid scales, and conus arteriosus in the heart.
ClasperIn biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's cloaca during mating. The act of mating in some fish including sharks usually includes one of the claspers raised to allow water into the siphon through a specific orifice.*As an Amazon Associate I earn from qualifying purchases.