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Polycotylids
Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to Leptocleididae. They are known as false pliosaurs. Polycotylids first appeared during the Albian stage of the Early Cretaceous, before becoming abundant and widespread during the early Late Cretaceous. Several species survived into the final stage of the Cretaceous, the early Maastrichtian around . The possible latest surviving member ''Rarosaurus'' from the late Maastrichtian is more likely a crocodylomorph. With their short necks and large elongated heads, they resemble the pliosaurs, but closer phylogenetic studies indicate that they share many common features with the Leptocleididae and Elasmosauridae. They have been found worldwide, with specimens reported from New Zealand, Australia, Japan, Morocco, the United States of America, US, Canada, Eastern Europe, and South America. Phylogeny Cladogram after Albright, Gillette and Titus (2007).Albright III, L. B., Gillette, D. D., and Titus, A. L., 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thililua
''Thililua'' is a genus of polycotylid plesiosaur, containing one species, ''T. longicollis''. Discovery The name ''Thililua'' is derived from that of an ancient aquatic god from local Berber mythology; ''longicollis'' refers to the animal's long neck. ''Thililua'' has been found in Late Cretaceous (early Turonian) rocks in the High Atlas mountains of Morocco in north Africa. ''Thililua'' is the first Polycotylid plesiosaur discovered in Africa, and also the first discovered that lived at a subtropical latitude. In 2010, ''Thililua'' was transferred to Leptocleididae as a sister taxon to '' Nichollssaura''. Description The type specimen of ''T. longicollis'', which was described in 2003, consists of an almost complete skull and lower jaw, articulated with 37 vertebrae. Of these vertebrae, 30 were cervical (neck) vertebrae, which is an unusually high number compared to other Polycotylids, such as '' Dolichorhynchops'', which had only 19 neck vertebrae, and '' Polycotylus'', wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 Megaannum#SI prefix multipliers, Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian–Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining Anoxic event#Cretaceous, early Aptian Oceanic Anoxic Event 1a (OAE1a) was dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java Plateau, Ontong Java-Manihiki Plateau, Manihiki-Hikurangi Plateau, Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Onto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scalamagnus
''Scalamagnus'' is an extinct genus of polycotylid plesiosaur from the Late Cretaceous Tropic Shale Formation of the United States. The genus contains a Monotypic taxon, single species ''S. tropicensis'', known from a skull and two partial skeletons. ''Scalamagnus'' was historically considered to represent a species of the genus ''Dolichorhynchops'' before it was moved to its own genus. History The taxon was first named as a species of ''Dolichorhynchops'' by Rebecca Schmeisser McKean in 2012 in paleontology, 2012. The specific name (zoology), specific name is derived from the name of the Tropic Shale, in which the two specimens were found. It is known from the holotype Museum of Northern Arizona, MNA V10046, an almost complete, well-preserved long skeleton including most of the skull and from the referred specimen MNA V9431, fragmentary postcranial elements. It was collected between 2003 and 2005 by the Museum of Northern Arizona from a single locality within the Tropi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elasmosauridae
Elasmosauridae, often called elasmosaurs or elasmosaurids, is an extinct family of plesiosaurs that lived from the Hauterivian stage of the Early Cretaceous to the Maastrichtian stage of the Late Cretaceous period (c. 130 to 66 mya). The taxon was initially erected in 1869 by Edward Drinker Cope to include the type genus '' Elasmosaurus'' with the related '' Cimoliasaurus'', although he did not argued in detail why. Over the following years, many authors recognized this classification on the basis of predominantly postcranial features, becoming one of the three groups in which plesiosaurs were often classified during the 19th century, along with the Pliosauridae and the Plesiosauridae. However, most of these traits led to many genera since recognized as belonging to other plesiosaur families being classified as elasmosaurids. Another family historically considered as distinct, the Cimoliasauridae, has since 2009 been recognized as a junior synonym of the Elasmosauridae. Along ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliosaur
Pliosauroidea is an extinct clade of plesiosaurs, known from the earliest Jurassic to early Late Cretaceous. They are best known for the subclade Thalassophonea, which contained crocodile-like short-necked forms with large heads and massive toothed jaws, commonly known as pliosaurs. More primitive non-thalassophonean pliosauroids resembled plesiosaurs in possessing relatively long necks and smaller heads. They originally included only members of the family Pliosauridae, of the order Plesiosauria, but several other genera and families are now also included, the number and details of which vary according to the classification used. The distinguishing characteristics are a short neck and an elongated head, with larger hind flippers compared to the fore flippers, the opposite of the plesiosaurs. They were carnivorous and their long and powerful jaws carried many sharp, conical teeth. Pliosaurs range from 4 to 10 meters or more in length. Their prey may have included fish, sharks, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crocodylomorph
Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably more ecologically diverse than modern crocodillians. The earliest and most primitive crocodylomorphs are represented by " sphenosuchians", a paraphyletic assemblage containing small-bodied, slender forms with elongated limbs that walked upright, which represents the ancestral morphology of Crocodylomorpha. These forms persisted until the end of the Jurassic. During the Jurassic, crocodylomorphs morphologically diversified into numerous niches, with the subgroups Neosuchia (which includes modern crocodilians) and the extinct Thalattosuchia adapting to aquatic life, while some terrestrial groups adopted herbivorous and omnivorous lifestyles. Terrestrial crocodylomorphs would continue to co-exist alongside aquatic forms until becoming extinct du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maastrichtian
The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (stratigraphy), Series, the Cretaceous geologic period, Period or system (stratigraphy), System, and of the Mesozoic geologic era, Era or Erathem. It spanned the interval from . The Maastrichtian was preceded by the Campanian and succeeded by the Danian (part of the Paleogene and Paleocene). It is named after the city of Maastricht, the capital and largest city of the Limburg (Netherlands), Limburg province in the Netherlands. The Cretaceous–Paleogene extinction event (formerly known as the Cretaceous–Tertiary period, Tertiary extinction event) occurred at the end of this age. In this extinction event, mass extinction, many commonly recognized groups such as non-avian dinosaurs, plesiosaurs and mosasaurs, as well as many other lesser-kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albian
The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/series (stratigraphy), Series. Its approximate time range is 113.0 ± 1.0 annum, Ma to 100.5 ± 0.9 Ma (million years ago). The Albian is preceded by the Aptian and followed by the Cenomanian. Stratigraphic definitions The Albian Stage was first proposed in 1842 by Alcide d'Orbigny. It was named after Alba, the Latin name for Aube (river), River Aube in France. A Global Boundary Stratotype Section and Point (GSSP), ratified by the IUGS in 2016, defines the base of the Albian as the first occurrence of the planktonic foraminiferan ''Hedbergellidae, Microhedbergella renilaevis'' at the Col de Pré-Guittard section, Arnayon, Drôme, France. The top of the Albian Stage (the base of the Cenomanian Stage and Upper Cretaceous Series) is defined ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leptocleididae
Leptocleididae is a family of small-sized plesiosaurs that lived during the Early Cretaceous period (early Berriasian to early Albian stage). They had small bodies with small heads and short necks. '' Leptocleidus'' and '' Umoonasaurus'' had round bodies and triangle-shaped heads. Leptocleidids have been found in what were shallow nearshore, freshwater and brackish habitats. Hilary F. Ketchum and Roger B. J. Benson (2010), transferred '' Brancasaurus'', '' Kaiwhekea'', '' Nichollssaura'' and ''Thililua ''Thililua'' is a genus of polycotylid plesiosaur, containing one species, ''T. longicollis''. Discovery The name ''Thililua'' is derived from that of an ancient aquatic god from local Berber mythology; ''longicollis'' refers to the animal's lo ...'' to this family. However, Ketchum and Benson (2011) reassigned ''Kaiwhekea'' and ''Thililua'' to their original positions, as an elasmosaurid and a polycotylid, respectively. Phylogeny Cladogram based on Ketchum and Benson (2011) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ninth and longest geological period of the entire Phanerozoic. The name is derived from the Latin , 'chalk', which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation . The Cretaceous was a period with a relatively warm climate, resulting in high Sea level#Local and eustatic, eustatic sea levels that created numerous shallow Inland sea (geology), inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was largely ice-free, although there is some evidence of brief periods of glaciation during the cooler first half, and forests extended to the poles. Many of the dominant taxonomic gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiosaur
The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian stage, about 203 million years ago. They became especially common during the Jurassic Period, thriving until their disappearance due to the Cretaceous–Paleogene extinction event at the end of the Cretaceous Period, about 66 million years ago. They had a worldwide oceanic distribution, and some species at least partly inhabited freshwater environments. Plesiosaurs were among the first fossil reptiles discovered. In the beginning of the nineteenth century, scientists realised how distinctive their build was and they were named as a separate order in 1835. The first plesiosaurian genus, the eponymous ''Plesiosaurus'', was named in 1821. Since then, more than a hundred valid species have been described. In the early twenty-first cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unktaheela
''Unktaheela'' is an extinct genus of polycotylid plesiosaur from the Late Cretaceous Sharon Springs Formation of the United States. The genus contains a single species, ''U. '', known from two partial skeletons. ''Unktaheela'' represents the smallest known polycotylid. Discovery and naming The ''Unktaheela'' fossil material was discovered in sediments of the Sharon Springs Formation ('' Baculites obtusus'' zone) in the United States. The holotype specimen, UCM 35059, was found near Redbird in Niobrara County, Wyoming, and it consists of a skull with mandible and a nearly complete series of cervical, sacral, and caudal vertebrae, a partial series of dorsal vertebrae, partial pectoral and pelvic girdles, and elements of all the paddle limbs. The paratype specimen, SDSM 142501, was found near Buffalo Gap in Fall River County, South Dakota, and it consists of a complete skull, broken mandible, and five fragmentary remains of the postcrania that remain unidentified. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
