This timeline of ichthyosaur research is a chronological listing of events in the history of paleontology focused on the ichthyosauromorphs, a group of secondarily aquatic marine reptiles whose later members superficially resembled dolphins, sharks, or swordfish. Scientists have documented ichthyosaur fossils at least as far back as the late 17th century. At that time, a scholar named Edward Lhwyd published a book on British fossils that misattributed some ichthyosaur vertebrae to actual fishes; [1] their true nature was not recognized until the 19th century. In 1811, a boy named Joseph Anning discovered the first ichthyosaur fossils that would come to be scientifically recognized as such. [2] His sister Mary would later find the rest of its skeleton and would go on to become a respected fossil collector and paleontologist in her own right. [3]
Early researchers recognized ichthyosaurs as marine reptiles, but major aspects of their anatomy and behavior needed to be resolved. They were frequently portrayed as leaving the water to bask on rocks and with straight tails. [4] Although a bend in ichthyosaurs' tail vertebrae was seen from the earliest specimens, scholars assumed the bend reflected damage incurred to the animal's carcass after death. This bend was so common, however, that scholars eventually realized that it was natural and supported a shark-like tail fin. [5] Scientists came to realize that ichthyosaurs were too adapted to leave the water even to lay eggs. Evidence for live birth in ichthyosaurs dates back as far as 1846, when Chaning Pierce reported an apparent fossil Ichthyosaurus embryo to Sir Richard Owen. [6]
Ichthyosaur discoveries continued to be made into the 20th century. In 1928, Simeon Muller discovered the remains of 40 gigantic ichthyosaurs in Nevada. However, these remains would not be excavated until Charles Camp and Samuel Welles of Berkeley led an expedition for the purpose in the mid 1950s. [7] These fossils would take more than a decade to excavate, and the results of Camp's examination of the bones would not be published until a year after his 1975 death. These giant ichthyosaurs were named Shonisaurus popularis and their final resting place is now known as Berlin-Ichthyosaur state park. [8]
Other notable late 20th century advances in ichthyosaur research include the recognition of a new genus of ichthyosaur called Eurhinosaurus longirostris that had been misclassified as a species of Ichthyosaurus since 1854. [9] In 1986 Christopher McGowan would describe another, similar animal serendipitously discovered in England as Excalibosaurus , after King Arthur's mythical sword. [9] The late 1990s and early 21st century would see scholarly debate regarding the cause of the ichthyosaurs' extinction, especially regarding the potential role played by competition with the mosasaurs which had evolved around the time. [10]
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: CS1 maint: uses authors parameter (link)Ichthyosaurs are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia.
Ichthyosaurus is a genus of ichthyosaurs from the Early Jurassic, with possible Late Triassic record, from Europe. It is among the best known ichthyosaur genera, as it is the type genus of the order Ichthyosauria.
Ophthalmosaurus is a genus of ichthyosaur known from the Middle-Late Jurassic. Possible remains from the earliest Cretaceous, around 145 million years ago, are also known. It was a relatively medium-sized ichthyosaur, measuring 4 m (13 ft) long and weighing 930–950 kg (2,050–2,090 lb). Named for its extremely large eyes, it had a jaw containing many small but robust teeth. Major fossil finds of this genus have been recorded in Europe with a second species possibly being found in North America.
Temnodontosaurus is an extinct genus of ichthyosaur from the Early Jurassic period. They lived between 200 and 175 million years ago (Hettangian-Toarcian) in what is now Western Europe and possibly Chile. It lived in the deeper areas of the open ocean. University of Bristol paleontologist Jeremy Martin described the genus Temnodontosaurus as "one of the most ecologically disparate genera of ichthyosaurs," although the number of valid Temnodontosaurus species has varied over the years.
Stenopterygius is an extinct genus of thunnosaur ichthyosaur known from Europe.
Eurhinosaurus is an extinct genus of ichthyosaur from the Early Jurassic (Toarcian), ranging between 183 and 175 million years. Fossils of the aquatic reptile have been found in Western Europe. They used to live in the deep, open sea area. Eurhinosaurus was a large genus of ichthyosaurs. An adult individual could reach up to 7 metres (23 ft) in length.
Shastasauridae is an extinct family of Triassic ichthyosaurs that includes the genera Shastasaurus, Shonisaurus and Himalayasaurus. Many other Triassic ichthyosaurs have been assigned to Shastasauridae in the past, but recent phylogenetic analyses suggest that these species form an evolutionary grade of early ichthyosaurs rather than a true clade or evolutionary grouping that can be called Shastasauridae.
Contectopalatus was a primitive ichthyosaur, an extinct fish-like marine reptile from the Middle Triassic of Germany and China. It was originally named Ichthyosaurus atavus by Quenstedt in 1852, and later reassigned to Mixosaurus. It was recognised as a separate genus by Maisch and Matzke in 1998, though other researchers have classified it as a species of Phalarodon instead.
Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous worldwide. Almost all ichthyosaurs from the Middle Jurassic onwards belong to the family, until the extinction of ichthyosaurs in the early Late Cretaceous. Opthalmosaurids appeared worldwide during early Bajocian, subsequent to the disappearance of most other ichthyosaur lineages after the end of the Toarcian. Currently, the oldest known ophthalmosaurids is Mollesaurus from the early Bajocian of Argentina, as well as indeterminate remains of the same age from Luxembourg and Canada. Named by George H. Baur, in 1887, the family contains the basal taxa like Ophthalmosaurus. Appleby (1956) named the taxon Ophthalmosauria which was followed by some authors, but these two names are often treated as synonyms; Ophthalmosauridae has the priority over Ophthalmosauria. However, some researchers argue that Ophthalmosauridae should be restricted to the group typically referred to as Ophthalmosaurinae, with classic Platypterygiinae instead being referred to as Undorosauridae or Brachypterygiidae and Ophthalmosauria being used to unite these two groups.
Brachypterygius is an extinct genus of platypterygiine ophthalmosaurid ichthyosaur known from the Late Jurassic of England. The type species was originally described and named as Ichthyosaurus extremus by Boulenger in 1904. Brachypterygius was named by Huene in 1922 for the width and shortness of the forepaddle, and the type species is therefore Brachypterygius extremus. The holotype of B. extremus was originally thought to be from the Lias Group of Bath, United Kingdom, but other specimens suggest it more likely came from the Kimmeridgian Kimmeridge Clay of Kimmeridge Bay, Dorset, UK.
Chacaicosaurus is a genus of neoichthyosaurian ichthyosaur known from the Middle Jurassic of Argentina. The single known specimen of this genus was excavated from the Los Molles Formation in Neuquén Province, and is housed at the Museo Olsacher under the specimen number MOZ 5803. This specimen consists of a skull, forelimb, some vertebrae, and some additional postcranial elements. The genus was named by Marta Fernández in 1994, and contains a single species, Chacaicosaurus cayi, making it the first named distinctive ichthyosaur from the Bajocian stage. It is a medium-sized ichthyosaur with a very long snout, which bears a ridge running along each side. The forelimbs of Chacaicosaurus are small and contain four main digits.
Leptonectes is a genus of ichthyosaur that lived in the Late Triassic to Early Jurassic. Fossils have been found in Belgium, Germany, Switzerland, Spain and the United Kingdom. The type species, L. tenuirostris, reached 4 metres (13 ft) long, while L. moorei reached 3 metres (9.8 ft) long; the largest species, L. solei, was approximately 5–6 metres (16–20 ft) long.
Protoichthyosaurus is a genus of ichthyosaur from the early Jurassic of southern England. Two species are known, P. prostaxalis—the type species, named by Appleby in 1979—and P. applebyi. A third species, P. prosostealis, was named by Appleby, but it was removed from the genus in 2017 due to its similarity to Ichthyosaurus. The genus Protoichthyosaurus was synonymized with Ichthyosaurus by Maisch and Hungerbuhler in 1997, and again by Maisch and Matzke in 2000. However, it was found to be distinct in 2017 by Dean Lomax and colleagues, who separated it from Ichthyosaurus on account of differences in the arrangement and shape of the carpal ossifications, as well as the absence of the fifth digit. The species most likely lived during the Hettangian stage, but may have lived as early as the Rhaetian and as late as the Sinemurian.
Grendelius is a genus of platypterygiine ophthalmosaurid ichthyosaur from the Late Jurassic (Kimmeridgian-Tithonian) of the UK and European Russia. It was a medium-sized ichthyosaur measuring about 4 metres (13 ft) long.
Parvinatator, from Latin, “parvus” little and “natator” swimmer, is an extinct genus of small ichthyopterygian marine reptile that lived during the Early to Middle Triassic. Its fossils have been found in British Columbia, Canada.
Macgowania is an extinct genus of parvipelvian ichthyosaur known from British Columbia of Canada.
Parvipelvia is an extinct clade of euichthyosaur ichthyosaurs that existed from the Late Triassic to the early Late Cretaceous of Asia, Australia, Europe, North America and South America. Named by Ryosuke Motani, in 1999, it contains the basal taxa like Macgowania and Hudsonelpidia. Maisch and Matzke (2000) found in their analysis seven synapomorphies that support Parvipelvia. They also found 10 synapomorphies that support the existence of post-Triassic clade of ichthyosaurs, for which the name Neoichthyosauria was found to be available. Parvipelvians were the only ichthyosaurs to survive the Triassic-Jurassic extinction event.
Acamptonectes is a genus of ophthalmosaurid ichthyosaurs, a type of dolphin-like marine reptiles, that lived during the Early Cretaceous around 130 million years ago. The first specimen, a partial adult skeleton, was discovered in Speeton, England, in 1958, but was not formally described until 2012 by Valentin Fischer and colleagues. They also recognised a partial subadult skeleton belonging to the genus from Cremlingen, Germany, and specimens from other localities in England. The genus contains the single species Acamptonectes densus; the generic name means "rigid swimmer" and the specific name means "compact" or "tightly packed".
Pervushovisaurus is a genus of platypterygiine ichthyosaur from the Late Cretaceous (Cenomanian) of the Saratov region in western Russia, the La Penthiève Beds of France and the Cambridge area of the UK.
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