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Antlers Formation
The Antlers Formation is a stratum which ranges from Arkansas through southern Oklahoma into northeastern Texas. The stratum is thick consisting of silty to sandy mudstone and fine to coarse grained sandstone that is poorly to moderately sorted. The stratum is cemented with clay and calcium carbonate. In places the sandstone may be conglomeratic or ferruginous (rich in iron oxides). Based on correlation with the Trinity Group of Texas, the Antlers Formation is estimated to be late Aptian-early Albian. This age range is supported by the presence of two dinosaurs that are also known from the Cloverly Formation, ''Deinonychus'' and '' Tenontosaurus''. Amphibians Indeterminate frog remains. Possible indeterminate salamander remains. Fish References: Cifelli ''et al.'' 1999; Wedel ''et al.'' 2000, Kielan-Jarorowska and Cifelli 2001; Nydam and Cifelli 2002. Cartilaginous fish Ray-finned fish Possible indeterminate amid remains. Possible indeterminate lepisosteid remains. Po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deinonychus
''Deinonychus'' ( ; ) is a genus of dromaeosaurid theropod dinosaur with one described species, ''Deinonychus antirrhopus''. This species, which could grow up to long, lived during the early Cretaceous Period, about 115–108 million years ago (from the mid-Aptian to early Albian stages). Fossils have been recovered from the U.S. states of Montana, Utah, Wyoming, and Oklahoma, in rocks of the Cloverly Formation, Cedar Mountain Formation and Antlers Formation, though teeth that may belong to ''Deinonychus'' have been found much farther east in Maryland. Paleontologist John Ostrom's study of ''Deinonychus'' in the late 1960s revolutionized the way scientists thought about dinosaurs, leading to the " dinosaur renaissance" and igniting the debate on whether dinosaurs were warm-blooded or cold-blooded. Before this, the popular conception of dinosaurs had been one of plodding, reptilian giants. Ostrom noted the small body, sleek, horizontal posture, ratite-like spine, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astroconodon
''Astroconodon'' is an extinct genus of mammal from the Cretaceous of North America. Part of Eutriconodonta, it was a small sized predator, either a terrestrial insectivore and carnivore, or a semi-aquatic piscivore. It is the first Cretaceous eutriconodont found. Description The type species is ''A. denisoni''. Known from the Antlers Formation, its type specimen, ''FMNH PM 542'', was first described by Bryan Patterson in 1951. It is a generally rather common species, known from a large quantity of isolated teeth, exhibiting a high degree of variability. Its molars are on average 0.59 to 2 millimeters long, and the distal ones see a marked increase in crown height. A second species, ''A. delicatus'', was later found in the Cedar Mountain Formation. Its type locality is Mussentuchit (OMNH V239). It is smaller than ''A. denisoni'' by approximately 80%, and it differs from it, and most North American triconodontids, by lacking a lingual cingulid on the lower molars and premo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles (including birds) from which they diverged in the Carboniferous, over 300 million years ago. Around 6,400 extant species of mammals have been described divided into 29 orders. The largest orders, in terms of number of species, are the rodents, bats, and Eulipotyphla ( hedgehogs, moles, shrews, and others). The next three are the Primates (including humans, apes, monkeys, and others), the Artiodactyla (cetaceans and even-toed ungulates), and the Carnivora ( cats, dogs, seals, and others). In terms of cladistics, which reflects evolutionary history, mammals are the only living members of the Synapsida (synapsids); this clade, toget ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeobalistum
''Palaeobalistum'' is an extinct genus of prehistoric ray-finned fish which ranged from the Cretaceous to Eocene periods. Etymology The Latin genus name derives from a Greek word meaning "thick tooth". Species The following species have been described: * '' Palaeobalistum dossantosi'' Maury, 1930 * '' Palaeobalistum flavellatum'' Cope, 1886 * '' Palaeobalistum geiseri'' Thurmond, 1974 * '' Palaeobalistum goedeli'' Heckel, 1856Neal RobbinPaleobalistum goedeli/ref> * '' Palaeobalistum gutturosum'' Arambourg, 1954 * '' Palaeobalistum libanicum'' Kramberger, 1895 * '' Palaeobalistum orbiculatum'' Blainville, 1818 * '' Palaeobalistum ponsortii'' Heckel, 1854 * '' Palaeobalistum rectidens'' Thurmond, 1974 * '' Palaeobalistum zignoi'' Blot, 1987 Distribution Fossils of ''Palaeobalistum'' have been found in: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyronchus
''Gyronchus'' is an extinct genus of prehistoric ray-finned fish from the Jurassic. See also * Prehistoric fish The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fis ... * List of prehistoric bony fish External links Bony fish in the online Sepkoski Database Jurassic bony fish Pycnodontiformes genera Jurassic fish of North America {{Jurassic-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinopterygian
Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or horny spines (rays), as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii (lobe-finned fish). These actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the link or connection between these fins and the internal skeleton (e.g., pelvic and pectoral girdles). By species count, actinopterygians dominate the vertebrates, and they constitute nearly 99% of the over 30,000 species of fish. They are ubiquitous throughout freshwater and marine environments from the deep sea to the highest mountain streams. Extant species can range in size from ''Paedocypris'', at , to the massive ocean sunfish, at , and the long-bodied oarfish, at . The vast majority of Actinopte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lissodus
''Lissodus'' is an extinct genus of freshwater shark. It lived from the Early Carboniferous stage to the Albian age of the Cretaceous. It was about long and had flat teeth that it used for eating clams Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two .... References Prehistoric shark genera Mesozoic fish of Asia Jurassic sharks Mesozoic fish of Europe Hasle Formation {{Triassic-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybodus Fraasi (fossil)
''Hybodus'' (from el, ύβος , 'crooked' and el, ὀδούς 'tooth') is an extinct genus of hybodont, a group of shark-like elasmobranchs that lived from the Late Devonian to the end of the Cretaceous. Species closely related to the type species ''Hybodus reticulatus'' lived during the Early Jurassic epoch. Numerous species have been assigned to ''Hybodus'' spanning a large period of time, and it is currently considered a wastebasket taxon that is 'broadly polyphyletic' and requires reexamination. The first fossilized teeth from ''Hybodus'' were found in England around 1845; since then teeth (and dorsal spines) have been recovered from Europe. During the Triassic, Jurassic, and Cretaceous periods, the hybodonts were especially successful and could be found in shallow seas around the world. For reasons that are not fully understood, the hybodonts became extinct near the end of the Late Cretaceous period. Description ''Hybodus'' species grew to about in length. It was not ver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybodus
''Hybodus'' (from el, ύβος , 'crooked' and el, ὀδούς 'tooth') is an extinct genus of hybodont, a group of shark-like elasmobranchs that lived from the Late Devonian to the end of the Cretaceous. Species closely related to the type species ''Hybodus reticulatus'' lived during the Early Jurassic epoch. Numerous species have been assigned to ''Hybodus'' spanning a large period of time, and it is currently considered a wastebasket taxon that is 'broadly polyphyletic' and requires reexamination. The first fossilized teeth from ''Hybodus'' were found in England around 1845; since then teeth (and dorsal spines) have been recovered from Europe. During the Triassic, Jurassic, and Cretaceous periods, the hybodonts were especially successful and could be found in shallow seas around the world. For reasons that are not fully understood, the hybodonts became extinct near the end of the Late Cretaceous period. Description ''Hybodus'' species grew to about in length. It was not ver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrichthyan
Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue. Chondrichthyes are jawed vertebrates with paired fins, paired nares, scales, and a heart with its chambers in series. Extant chondrichthyes range in size from the 10 cm (3.9 in) finless sleeper ray to the 10 m (32 ft) whale shark. The class is divided into two subclasses: Elasmobranchii ( sharks, rays, skates, and sawfish) and Holocephali (chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, except in Holocephali, where the notochord stays intact. In some d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albanerpeton BW
''Albanerpeton'' is an extinct genus of salamander-like lissamphibian found in North America and Europe, first appearing in Cretaceous-aged strata. There are eight described members of the genus, and one undiagnosed species from the Paskapoo Formation, with the most recent, ''A. ektopistikon'' being described by Carrano ''et al.''in 2022. Members of the genus had a robust head and neck which likely allowed them to actively burrow, characteristic of fossorial species, and they lived in a wide range of environments. This genus of amphibian was the last of its order, surviving until the late Pliocene in southern Europe, and into the Early Pleistocene (Gelasian) of northern Italy. It likely became extinct when the region developed its present Mediterranean-type climate, having preferred one that was cold and humid. The monophyly of ''Albanerpeton'' has recently been questioned History and Discovery Albanerpeton was first described by Estes and Hoffstetter in 1976. However, the gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
