|
Ojo Alamo Formation
The Ojo Alamo Formation is a geologic formation in New Mexico spanning the Mesozoic/Cenozoic boundary. Non-avian dinosaur fossils have controversially been identified in beds of this formation dating from after the Cretaceous–Paleogene extinction event, but these have been explained as either misidentification of the beds in question or as reworked fossils, fossils eroded from older beds and redeposited in the younger beds. Description The Ojo Alamo Formation is divided into two subunits separated by a large unconformity—a gap in the geologic record. The lower Naashoibito member (sometimes considered part of the Kirtland Formation) was deposited during the Maastrichtian age of the Cretaceous period, specifically between about 69-68 million years ago. It overlies the De-na-zin member of the Kirtland formation, though the two are separated by another large unconformity that spans a period of geologic time equivalent to 73-69 million years ago.Sullivan, R.M., and Lucas, S.G. 2006. ... [...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 Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleogene
The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago (annum, Mya) to the beginning of the Neogene Period Mya. It is the beginning of the Cenozoic Era of the present Phanerozoic Eon. The earlier term Tertiary Period was used to define the span of time now covered by the Paleogene Period and subsequent Neogene Period; despite no longer being recognised as a formal stratigraphy, stratigraphic term, 'Tertiary' is still widely found in earth science literature and remains in informal use. Paleogene is often abbreviated "Pg" (but the United States Geological Survey uses the abbreviation PE for the Paleogene on the Survey's geologic maps). During the Paleogene, evolution of mammals, mammals diversified from relatively small, simple forms into a large group of diverse animals in the wake of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurankylus
''Neurankylus'' is an extinct genus of turtles in the family Baenidae that lived between 112 and 61 million years ago in Canada and the United States. It was originally placed within the monotypic family Neurankylidae, but it has since been placed in the Neurankylinae, alongside '' Trinitichelys''. The type species, ''Neurankylus eximius'', was described by Lawrence Lambe in 1902. The species ''N. lithographicus'' was discovered in the Milk River Formation (Canada), alongside the holotype of the pachycephalosaurid dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ... '' Acrotholus audeti''. References {{Taxonbar, from1=Q73170070 Baenidae Cretaceous turtles Paleocene turtles Cretaceous reptiles of North America Paleocene reptiles of North America Hell Creek fauna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hoplochelys
''Hoplochelys'' is an extinct genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ... of kinosternoid. References Kinosternidae Late Cretaceous turtles of North America Cretaceous reptiles of North America Hell Creek fauna {{paleo-turtle-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compsemys
''Compsemys '' is an extinct genus of prehistoric turtles from the Late Cretaceous and Paleocene of North America and possibly Europe. The type species ''C. victa'', first described by Joseph Leidy from the Hell Creek Formation in Montana in 1856, and another probable species ''C. russelli'' (originally placed in the separate genus '' Berruchelus''), described in 2012, from Paleocene deposits in France''.'' Its affinites have long been uncertain, but it has recently been considered to be the most basal member of Paracryptodira, despite the clade first appearing in the Late Jurassic, and is sometimes included in its own family, Compsemydidae. A revision in 2020 found Compsemydidae to be more expansive, also containing '' Riodevemys'' and '' Selenemys'' from the Late Jurassic of Europe, and '' Peltochelys'' from the Early Cretaceous of Europe. ''Compsemys'' was a moderately sized turtle, up to long, with a carapace covered with raised, flattened tubercles, which are not seen in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caudata
The Caudata are a group of amphibians containing the extant salamanders (Urodela) and all extinct species of amphibians more closely related to salamanders than to frogs. They are typically characterized by a superficially lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. Disagreement exists between different authorities as to the definition of the terms "Caudata" and "Urodela". Some maintain that Urodela should be restricted to the crown group, with Caudata being used for the total group. Others restrict the name Caudata to the crown group and use Urodela for the total group. The former approach seems to be most widely adopted and is used in this article. Evolution The origins and evolutionary relationships between the three main groups of amphibians ( apodans, urodeles and anurans) is a matter of debate. A 2005 molecular phylogeny, based on rDNA analysis, suggest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteichthyes
Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilage. The vast majority of fish are members of Osteichthyes, which is an extremely diverse and abundant group consisting of 45 orders, and over 435 families and 28,000 species. It is the largest class of vertebrates in existence today. The group Osteichthyes is divided into the ray-finned fish (Actinopterygii) and lobe-finned fish (Sarcopterygii). The oldest known fossils of bony fish are about 425 million years old, which are also transitional fossils, showing a tooth pattern that is in between the tooth rows of sharks and bony fishes. Osteichthyes can be compared to Euteleostomi. In paleontology the terms are synonymous. In ichthyology the difference is that Euteleostomi presents a cladistic view which includes the terrestrial tetrap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lepisosteus
''Lepisosteus'' is a genus of gars in the family Lepisosteidae. Distribution While in the present day, ''Lepisosteus'' is only known across North America, fossil remains show it was much more widespread in the past, with specimens known from the Cretaceous of India and Brazil. Systematics Species The currently recognized species are: Extant species Fossil species * †''Lepisosteus aganus'' (Cope, 1877) * †''Lepisosteus bemisi'' Grande, 2010 * †''Lepisosteus bohemicus'' (Laube, 1901) * †''Lepisosteus cominatoi'' Santos, 1984 * †''Lepisosteus cycliferus'' (Cope, 1873) * †''Lepisosteus glaber'' Marsh, 1871 * †'' Lepisosteus indicus'' Woodward, 1908 * †'' Lepisosteus integer'' (Cope, 1877) * †'' Lepisosteus fimbriatus'' Wood, 1846 * †'' Lepisosteus knieskerni'' Fowler, 1911 * †'' Lepisosteus longus'' Lambe, 1908 * †'' Lepisosteus nahunticus'' (Cope, 1869) * †'' Lepisosteus notabilis'' Leidy, 1873 * †'' Lepisosteus occidentalis''Pearson ''et al.'', 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squatirhina
''Squatirhina'' is a genus of Late Cretaceous cartilaginous fish whose fossils have been found in the Aguja and Pen Formations of Big Bend National Park, Texas, USA. See also * List of prehistoric cartilaginous fish 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 vernacula ... Footnotes References * Hunt, ReBecca K., Vincent L. Santucci and Jason Kenworthy. 2006. "A preliminary inventory of fossil fish from National Park Service units." in S.G. Lucas, J.A. Spielmann, P.M. Hester, J.P. Kenworthy, and V.L. Santucci (ed.s), Fossils from Federal Lands. New Mexico Museum of Natural History and Science Bulletin 34, pp. 63–69. Prehistoric cartilaginous fish genera Cretaceous cartilaginous fish Late Cretaceous fish of North America Laramie Formation Ojo Alamo Formation {{p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myledaphus
''Myledaphus'' is a genus of Late Cretaceous cartilaginous fish whose fossils are known from Canada, the Midwest of the United States, Olmos Formation of the Difunta Group of Mexico, and the Beshtyubin and Bissekty Formations of Uzbekistan. It was a freshwater guitarfish that probably reached a length of , and had teeth adapted for a durophagous diet of animals such as clams. Most taxonomic authories place the genus in the Rhinobatidae. Two species are known: ''Myledaphus bipartitus'', the type species, and ''Myledaphus araucanus'', named in 2019. Fossils and age The most common remains of this fish are teeth and vertebra. A study performed on ''Myledaphus'' vertebra from Alberta in 2013 revealed that ''Myledaphus'' had an estimated maximum age of 16 years. This means that ''Myledaphus'' had a shorter lifespan than that of the modern common guitarfish, by a difference of 8 years. See also * List of prehistoric cartilaginous fish This list of prehistoric cartilaginous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Lepisosteus")
