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The ichthyosaurs, plesiosaurs, and pterosaur she found, along with the first dinosaur fossils which were discovered by Gideon Mantell and William Buckland during the same period, showed that during previous eras the earth was inhabited by creatures very different from those living today, and provided important support for another controversial suggestion of Cuvier's: that there had been an " age of reptiles " when reptiles rather than mammals had been the dominant form of animal life.
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ichthyosaurs and plesiosaurs
Marine reptiles included ichthyosaurs in the early and middle of the Cretaceous ( becoming extinct during the late Cretaceous Cenomanian-Turonian anoxic event ), plesiosaurs throughout the entire period, and mosasaurs appearing in the Late Cretaceous.
The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, while pterosaurs were the dominant flying vertebrates.
Animal life was then dominated by large archosaurian reptiles: dinosaurs, pterosaurs, and aquatic reptiles such as ichthyosaurs, plesiosaurs, and mosasaurs.
Wagler went so far as to classify Pterodactylus, along with other aquatic vertebrates ( namely plesiosaurs, ichthyosaurs, and monotremes ), in the class Gryphi, between birds and mammals.
The term " dinosaur " is properly restricted to only those reptiles descended from the last common ancestor of the groups Saurischia and Ornithischia ( clade Dinosauria, which includes birds ), and current scientific consensus is that this group excludes the pterosaurs, as well as the various groups of extinct marine reptiles, such as ichthyosaurs, plesiosaurs, and mosasaurs.
It was to him she made what would prove to be the scientifically-important suggestion that the strange conical objects known as bezoar stones, were really the fossilised faeces of ichthyosaurs or plesiosaurs.
This speculation was confirmed over the next two decades by a series of spectacular finds, mostly by English geologists and fossil collectors such as Mary Anning, William Conybeare, William Buckland, and Gideon Mantell, who found and described the first ichthyosaurs, plesiosaurs, and dinosaurs.
Like the dinosaurs, the ichthyosaurs and their contemporaries the plesiosaurs survived the end-Triassic extinction event, and immediately diversified to fill the vacant ecological niches of the earliest Jurassic.
Therefore, marine viviparous species, including sea snakes and, it now appears, the mosasaurs, ichthyosaurs, and plesiosaurs of the Cretaceous, use genotypic sex determination ( sex chromosomes ), much like birds and mammals.
These marine reptiles had ancestors who moved back into the oceans, In the case of ichthyosaurs adapting as fully as the dolphins they superficially resemble, even giving birth to live offspring instead of laying eggs, in other cases more to the extent of the seal, as with plesiosaurs and placodonts.
During the Mesozoic era, many groups of reptiles became adapted to life in the seas, including such familiar clades as the ichthyosaurs, plesiosaurs ( these two orders were once thought united in the group " Enaliosauria ," a classification now cladistically obsolete ), mosasaurs, nothosaurs, placodonts, sea turtles, thalattosaurs and thalattosuchians.
Various creatures have evolved flippers, for example penguins ( also called " wings "), cetaceans ( e. g. dolphins and whales ; usually called " fins "), pinnipeds, and reptiles such as some varieties of turtle and the now-extinct plesiosaurs, mosasaurs, ichthyosaurs, and metriorhynchids.
Their prey may have included fish, sharks, ichthyosaurs, dinosaurs and other plesiosaurs.
The Hettangian saw the already existing Rhaetian ichthyosaurs and plesiosaurs continuing to flourish, while at the same time a number of new types of these marine reptiles appeared, such as Ichthyosaurus and Temnodontosaurus among the ichthyosaurs, and Eurycleidus, Macroplata, and Rhomaleosaurus among the plesiosaurs ( all Rhomaleosauridae, although as currently defined this group is probably paraphyletic ).
In the Toarcian, at the end of the Early Jurassic, the thalattosuchians ( marine " crocodiles ") appeared, as did new genera of ichthyosaurs ( Stenopterygius, Eurhinosaurus, and the persistently primitive Suevoleviathan ) and plesiosaurs ( the elasmosaurs ( long-necked ) Microcleidus and Occitanosaurus, and the pliosaur Hauffiosaurus ).
ichthyosaurs and found
A recent study examined 94 living species of reptiles, birds and mammals and found that the genetic control of sex appears to be crucial to live birth and that genetics likely controlled gender in ichthyosaurs, mosasaurs and other extinct marine reptiles.
ichthyosaurs and with
Parapsida was later discarded as a group for the most part ( ichthyosaurs being classified as incertae sedis or with Euryapsida ).
Apart from the obvious similarities to fish, the ichthyosaurs also shared parallel developmental features with dolphins, lamnid sharks, and tuna.
Buckland also suspected that the spiral markings on the fossils indicated that ichthyosaurs had spiral ridges in their intestines similar to those of modern sharks, and that some of these coprolites were black with ink from swallowed belemnites.
In 1821, in collaboration with Henry De la Beche he distinguished himself by describing, from fragmentary remains, the saurian Plesiosaurus in a paper for the Geological that also contained an important description and analysis of all that had been learned to that point about the anatomy of ichthyosaurs including the fact that there had been at least three different species.
ichthyosaurs and which
Fossils discovered in the lias include many ichthyosaurs, one of which has been adopted as the badge of Street.
In fact the earliest reconstructions of ichthyosaurs omitted the dorsal fin, which had no hard skeletal structure, until finely-preserved specimens recovered in the 1890s from the Holzmaden lagerstätten in Germany revealed traces of the fin.
These very early proto-ichthyosaurs, which are now classified as Ichthyopterygia rather than as ichthyosaurs proper ( Motani 1997, Motani et al.
The Early Jurassic, like the Late Triassic, was the heyday of the ichthyosaurs, which are represented by four families and a variety of species, ranging from one to ten metres in length.
Their boats were originally squids, their submarines are enhanced ichthyosaurs ( here called uruketos ), and their guns are evolved monitor lizards which eject projectiles using pressurised gas.
ichthyosaurs and were
They concluded that ichthyosaurs were a previously unknown type of marine reptile, and based on differences in tooth structure, they concluded that there had been at least three species.
She noted that if such stones were broken open they often contained fossilised fish bones and scales, and sometimes bones from small ichthyosaurs.
There is ample evidence that ichthyosaurs were negatively buoyant.
Although ichthyosaurs looked like fish, they were not.
She also noted that if such stones were broken open they often contained fossilized fish bones and scales as well as sometimes bones from smaller ichthyosaurs.
Ichthyopterygia (" fish flippers ") was a designation introduced by Sir Richard Owen in 1840 to designate the Jurassic ichthyosaurs that were known at the time, but the term is now used more often for both true Ichthyosauria and their more primitive early and middle Triassic ancestors.
By the later part of the Middle Triassic they were extinct, having been replaced by their descendents the true ichthyosaurs.
ichthyosaurs and same
Similar to convergent evolution, evolutionary relay describes how independent species acquire similar characteristics through their evolution in similar ecosystems, but not at the same time ( dorsal fins of sharks and ichthyosaurs ).
These large ( 10 to 15 metres long ) ichthyosaurs probably belong to the same genus as Shonisaurus ( Motani et al., 1999 ; Lucas, 2001, pp. 117 – 119 ).
Similar to convergent evolution, evolutionary relay describes how independent species acquire similar characteristics through their evolution in similar ecosystems, but not at the same time ( dorsal fins of sharks and ichthyosaurs ).
In the Mesozoic, similarly streamlined ichthyosaurs navigated the worlds oceans, yet another example of a group evolving a similar shape due to the same environmental factors.
ichthyosaurs and very
Typical ichthyosaurs have very large eyes, protected within a bony ring, suggesting that they may have hunted at night or at great depths.
Rhaetian ( latest Triassic ) ichthyosaurs are known from England, and these are very similar to those of the Early Jurassic.
ichthyosaurs and different
Evolutionary relay describes how independent species acquire similar characteristics through their evolution in similar ecosystems at different times — for example the dorsal fins of extinct ichthyosaurs and sharks.
ichthyosaurs and from
During the middle Triassic Period, ichthyosaurs evolved from as-yet unidentified land reptiles that moved back into the water, in a development parallel to that of the ancestors of modern-day dolphins and whales.
The earliest ichthyosaurs, looking more like finned lizards than the familiar fish-or dolphin-like forms, are known from the Early and Early-Middle ( Olenekian and Anisian ) Triassic strata of Canada, China, Japan, and Spitsbergen in Norway.
Ichthyosaurus ( derived from Greek ιχθυς / ichthys meaning ' fish ' and σαυρος / sauros meaning ' lizard ') is a genus of ichthyosaurs from the early Jurassic ( Hettangian-Sinemurian ) of Europe ( Belgium, England, Switzerland ).
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