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Priscagamidae
Priscagamidae is an extinct family of iguanian lizards known from the Late Cretaceous of Mongolia and China and the Eocene of India, spanning a range from 75 to 54 million years ago. It includes the genera ''Heterodontagama'', ''Mimeosaurus'', ''Phrynosomimus'', ''Priscagama'', and possibly ''Pleurodontagama''. The first fossils of priscagamids were found in the Djadochta and Khermeen Tsav formations of Mongolia. More recently they have been found in the Cambay Formation in India, leading to the naming of ''Heterodontagama'' in 2013. Priscagamidae was originally described as a subfamily of Agamidae called Priscagaminae in 1984, but it was reclassified as a distinct family in 1989. Most phylogenetic analyses (analyses of evolutionary relationships) still find a close relationship between Priscagamidae and Agamidae (both have been grouped under a clade called Chamaeleontiformes), although a 2015 study found it to be basal to all other iguanian clades, warranting its removal from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chamaeleontiformes
Chamaeleontiformes is a hypothesized clade (evolutionary grouping) of iguanian lizards defined as all taxa sharing a more recent common ancestor with ''Chamaeleo chamaeleon'' (the common chamaeleon) than with '' Hoplocercus spinosus'' (the Brazilian spiny-tailed lizard), ''Polychrus marmoratus'' (bush lizard), or '' Iguana iguana'' (green iguana). It was named by paleontologist Jack Conrad in 2008 to describe a clade recovered in his phylogenetic analysis that included the extinct genus ''Isodontosaurus'', the extinct family Priscagamidae, and the living clade Acrodonta, which includes agamids and chameleons. It is a stem-based taxon and one of two major clades within Iguania, the other being Pleurodonta. Below is a cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ... fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterodontagama
''Heterodontagama'' is an extinct genus of iguanian lizard from the Early Eocene of India. It belongs to the extinct family Priscagamidae, which is otherwise only known from the Late Cretaceous of Mongolia. The type species ''Heterodontagama borsukae'' was named in 2013 from several isolated upper and lower jaws found in an exposure of the Cambay Shale in an open-pit coal mine in Gujarat. ''Heterodontagama'' has a distinctively heterodont dentition. The two pairs of teeth at the front of the lower jaw are enlarged, pointed, and pleurodont, meaning that they grow from the inner surface of the jaw. The four following pairs of teeth are much smaller and acrodont Acrodonty (from Greek ''akros'' 'highest' + ''dont'' 'tooth') is an anatomical placement of the teeth at the summit of the alveolar ridge of the jaw, without sockets, characteristic of bony fish. Functionally, acrodont tooth implantation may be rela ..., meaning that they grow from the upper margin of the jaw. Behind them ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mimeosaurus
''Mimeosaurus'' is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia. It is part of an extinct family of iguanians called Priscagamidae, and was the first priscagamid to have been described, having been named by American paleontologist Charles W. Gilmore in 1943. Currently only one species, the type species ''Mimeosaurus crassus'', belongs within the genus. A second species, ''M. tugrikinensis'', was named in 1989, but later studies argued that the specimens on which the new name is based are not sufficiently different from ''M. crassus'' specimens to warrant being classified as a separate species. ''Mimeosaurus'' is unique among iguanians in having premaxilla bones at the tip of the snout that are reduced in size, as well as having two pairs of enlarged canine-like teeth in the maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In human ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phrynosomimus
''Phrynosomimus'' is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia belonging to the extinct family Priscagamidae. The type species ''Phrynosomimus asper'' was named in 1996. Fossils have been found in the Barun Goyot and Djadochta formations and include several complete skulls.''Phrynosomimus'' at .org ''Phrynosomimus'' has a short, triangular skull with bony spikes projecting from the back, stemming from the and |
Pleurodontagama
''Pleurodontagama'' is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia. The type species, ''Pleurodontagama aenigmatodes'', was named in 1984 on the basis of a mostly complete skull and isolated lower jaw from a fossil locality called Khermeen Tsav. It has a wide skull with a flat snout, large eye sockets, and small bumps on the surfaces of the bones. ''Pleurodontagama'' was initially classified in the family Priscagamidae, which is usually grouped in a large clade of iguanians called Acrodonta, members of which are characterized by an "acrodont" dentition in which the teeth grow from the margins of the jaws. However, ''Pleurodontagama'' is unusual in that it has a sub-pleurodont dentition, meaning that some of its teeth grow from the inner surfaces of the jaw. There is also evidence to suggest that its teeth may have been continuously replaced throughout life, as opposed to the permanent teeth of acrodontans. ''Pleurodontagama'' may have been a transition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Priscagama
''Priscagama'' (meaning "earliest '' Agama''" in Latin) is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia and China. It belongs to an extinct family of iguanians called Priscagamidae (or subfamily Priscagaminae). Several incomplete skulls have been found in the Barun Goyot and Djadochta formations, and were originally referred to the genus ''Mimeosaurus''; the type species ''Priscagama gobiensis'' was named in 1984 when it was recognized that these skulls belonged to a distinct species. ''Priscagama'' differs from most other priscagamids in having a more elongate, lightly built skull. It is very similar in appearance to another priscagamid called ''Pleurodontagama ''Pleurodontagama'' is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia. The type species, ''Pleurodontagama aenigmatodes'', was named in 1984 on the basis of a mostly complete skull and isolated lower jaw from a fossil lo ...'', as the two can only be distinguished by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iguania
Iguania is an infraorder of squamate reptiles that includes iguanas, chameleons, agamids, and New World lizards like anoles and phrynosomatids. Using morphological features as a guide to evolutionary relationships, the Iguania are believed to form the sister group to the remainder of the Squamata, which comprise nearly 11,000 named species, roughly 2000 of which are iguanians. However, molecular information has placed Iguania well within the Squamata as sister taxa to the Anguimorpha and closely related to snakes. The order has been under debate and revisions after being classified by Charles Lewis Camp in 1923 due to difficulties finding adequate synapomorphic morphological characteristics. Most Iguanias are arboreal but there are several terrestrial groups. They usually have primitive fleshy, non-prehensile tongues, although the tongue is highly modified in chameleons. The group has a fossil record that extends back to the Early Jurassic (the oldest known member is '' B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia although some lizards are more closely related to these two excluded groups than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon. Most lizards are quadrupedal, running with a strong side-to-side motion. Some lineages (known as "legless lizards"), have secondarily lost their legs, and have long snake-like bodies. Some such as the forest-dwelling ''Draco'' lizards are able to glide. They are often territorial, the males fighting off other males and signalling, often with bright colours, to attract mates and to intimidate rivals. Lizards are mainly carnivorous, often being sit-and-wait predators; many smaller species eat insects, while the Komodo eats mammals a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iguanomorpha
Iguania is an infraorder of squamate reptiles that includes iguanas, chameleons, agamids, and New World lizards like anoles and phrynosomatids. Using morphological features as a guide to evolutionary relationships, the Iguania are believed to form the sister group to the remainder of the Squamata, which comprise nearly 11,000 named species, roughly 2000 of which are iguanians. However, molecular information has placed Iguania well within the Squamata as sister taxa to the Anguimorpha and closely related to snakes. The order has been under debate and revisions after being classified by Charles Lewis Camp in 1923 due to difficulties finding adequate synapomorphic morphological characteristics. Most Iguanias are arboreal but there are several terrestrial groups. They usually have primitive fleshy, non-prehensile tongues, although the tongue is highly modified in chameleons. The group has a fossil record that extends back to the Early Jurassic (the oldest known member is '' Bharat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Australia and Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, the equivalent Latin term ''cladus'' (plural ''cladi'') is often used in taxonomical literature. The common ancestor may be an individual, a population, or a species (extinct or extant). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic. Some of the relationships between organisms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene Extinctions
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn") and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the ''Grande Coupure'' (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay. As with other geologic periods, the strata that define the start and end of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
