Pliosaur
Encyclopedia
Pliosauroidea is an extinct clade
of marine
reptiles. Pliosauroids, also commonly known as pliosaurs, are known from the Jurassic
and Cretaceous
Periods. The pliosauroids were short-necked plesiosaur
s with large heads and massive toothed jaws. These swimming reptiles were not dinosaur
s but distant cousins of modern lizard
s. 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, vice-versa of the plesiosaurs. They were carnivorous
and their long and powerful jaws carried many sharp, conical teeth. Pliosaurs range from 4 to 15 metres and more in length. Their prey may have included fish
, sharks, ichthyosaur
s, dinosaur
s and other plesiosaurs.
The largest known genera are Liopleurodon
and Kronosaurus
; other well known genera include Rhomaleosaurus
, Peloneustes
, and Macroplata
. Fossil specimens have been found in Africa
, Australia
, China
, Europe
, North America
and South America
.
Many very early (from the Early Jurassic
and possibly Rhaetian
(Latest Triassic)) primitive pliosauroids were very like plesiosauroids in appearance and indeed used to be included in the family Plesiosauridae
.
, which is derived from Greek
, πλειων meaning "more/closely" and σαυρος meaning "lizard"; it therefore means "more saurian". The name Pliosaurus was coined in 1841 by Richard Owen
, who believed that it represented a link between plesiosauroids and crocodilians (considered a type of "saurian"), particularly due to their crocodile-like teeth.
The taxonomy presented here is mainly based on the plesiosaur cladistic analysis proposed by Hilary F. Ketchum and Roger B. J. Benson, 2011 unless otherwise noted.
Pliosauroidea is a stem-based taxon which was defined by Welles as "all taxa more closely related to Pliosaurus brachydeirus than to Plesiosaurus dolichodeirus". Pliosauridae and Rhomaleosauridae are stem-based taxons too. Pliosauridae is defined as "all taxa more closely related to Pliosaurus brachydeirus than to Leptocleidus superstes, Polycotylus latipinnis or Meyerasaurus victor". Rhomaleosauridae is defined as "all taxa more closely related to Meyerasaurus victor than to Leptocleidus superstes, Pliosaurus brachydeirus or Polycotylus latipinnis". The cladogram
below follows a 2011 analysis by paleontologists Hilary F. Ketchum and Roger B. J. Benson, and reduced to genera only.
. This pliosauroid came to be known as the "Monster of Aramberri". The size of this specimen has been estimated to be about 15 metres (49.2 ft) long and it had a 3 metres (10 ft) long skull. Consequently, although widely reported as such, it does not belong to the genus Liopleurodon. The remains of this animal, consisting of a partial vertebral column, were dated to the Kimmeridgian
of the La Caja Formation. The fossils were found much earlier, in 1985, by a geology student and were at first erroneously attributed to a theropod dinosaur
by Hahnel. The remains originally contained part of a rostrum with teeth (now lost).
In August 2006, palaeontologists of the University of Oslo discovered the first remains of a pliosaur on Norwegian soil. The remains were described as "very well preserved as well as being unique in their completeness" and are the first complete skeleton of a pliosaur ever discovered. Whether it belongs to the genus Pliosaurus or Liopleurodon awaits publication of the fossil description. In the summer of 2008, the fossil remains of the huge pliosaur were dug up from the permafrost on Svalbard
, a Norwegian island close to the North Pole
. The excavation of the find is documented in the 2009 History television special Predator X
.
On 26 October 2009 palaeontologists reported the discovery of potentially the largest pliosauroid yet found, discovered in cliffs near Weymouth, Dorset
, on Britain's Jurassic coast
. The fossil had a skull length of 2.4 metres (7.9 ft) and a body length of 16 metres (52.5 ft). Palaeontologist Richard Forrest told the BBC: "I had heard rumours that something big was turning up. But seeing this thing in the flesh, so to speak, is just jaw dropping. It is simply enormous."
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
of marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
reptiles. Pliosauroids, also commonly known as pliosaurs, are known from the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
and Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
Periods. The pliosauroids were short-necked plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
s with large heads and massive toothed jaws. These swimming reptiles were not dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s but distant cousins of modern lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s. They originally included only members of the family Pliosauridae
Pliosauridae
Pliosauridae is a family of pliosauroid plesiosaurs from the Earliest Jurassic to the early Late Cretaceous of Australia, Europe, North America and South America. It was formally named by Harry G...
, of the order Plesiosauria
Plesiosauria
Plesiosauria is an order of Mesozoic marine reptiles. Plesiosaurs first appeared in the Early Jurassic Period and became especially common during the Jurassic Period, thriving until the K-T extinction at the end of the Cretaceous Period.The name "plesiosaur" is used to refer to the order...
, 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, vice-versa of the plesiosaurs. They were carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
and their long and powerful jaws carried many sharp, conical teeth. Pliosaurs range from 4 to 15 metres and more in length. Their prey may have included fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, sharks, ichthyosaur
Ichthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...
s, dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s and other plesiosaurs.
The largest known genera are Liopleurodon
Liopleurodon
Liopleurodon is a genus of large, carnivorous marine reptile belonging to the Pliosauroidea, a clade of short-necked plesiosaurs. Two species of Liopleurodon lived during the Callovian stage of the Middle Jurassic Period , while the third, L. rossicus, lived during the Late Jurassic...
and Kronosaurus
Kronosaurus
Kronosaurus is an extinct genus of short-necked pliosaur. It was among the largest pliosaurs, and is named after the leader of the Greek Titans, Cronus.-Discovery and species:Kronosaurus lived in the Early Cretaceous Period ....
; other well known genera include Rhomaleosaurus
Rhomaleosaurus
Rhomaleosaurus is an extinct genus of Early Jurassic rhomaleosaurid pliosauroid known from Northamptonshire and from Yorkshire of the United Kingdom. It was first named by Harry Seeley in 1874 and the type species is Rhomaleosaurus cramptoni...
, Peloneustes
Peloneustes
Peloneustes is an extinct genus of sauropterygian reptile belonging to the family Pliosauridae. It is known from the Callovian aged deposits of the Oxford clay formation of England...
, and Macroplata
Macroplata
Macroplata , meaning, , is an extinct genus of Early Jurassic basal plesiosaur which grew up to in length. Like other plesiosaurs, Macroplata probably lived on a diet of fish, using its sharp needle-like teeth to catch prey. Its shoulder bones were fairly large, indicating a powerful forward...
. Fossil specimens have been found in Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
.
Many very early (from the Early Jurassic
Early Jurassic
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...
and possibly Rhaetian
Rhaetian
The Rhaetian is in geochronology the latest age of the Triassic period or in chronostratigraphy the uppermost stage of the Triassic system. It lasted from 203.6 ± 1.5 to 199.6 ± 0.6 million years ago...
(Latest Triassic)) primitive pliosauroids were very like plesiosauroids in appearance and indeed used to be included in the family Plesiosauridae
Plesiosauridae
Plesiosauridae was a monophyletic family of plesiosaurs.-References:...
.
Name
Pliosauroidea was named by Welles in 1943. It is adapted from the name of the genus PliosaurusPliosaurus
Pliosaurus is a genus of extinct marine reptile. It is included in the family Pliosauridae. Its diet would have included fish, squid and other marine reptiles. This genus has contained several species in the past but it currently consists of the type species P. brachydeirus, P. macromerus and P...
, which is derived from Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
, πλειων meaning "more/closely" and σαυρος meaning "lizard"; it therefore means "more saurian". The name Pliosaurus was coined in 1841 by Richard Owen
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...
, who believed that it represented a link between plesiosauroids and crocodilians (considered a type of "saurian"), particularly due to their crocodile-like teeth.
Taxonomy
- Suborder Pliosauroidea
- ? MegalneusaurusMegalneusaurusMegalneusaurus is an extinct genus of large pliosaur that lived in the Sundance Sea during the Kimmeridgian, ~156-152 million years ago, in the Late Jurassic....
- ? PachycostasaurusPachycostasaurusPachycostasaurus is an extinct genus of plesiosaur....
- ? SinopliosaurusSinopliosaurusSinopliosaurus is a genus of pliosauroid plesiosaur, a type of short-necked marine reptile, from the Early Cretaceous of People's Republic of China. One species, "S." fusuiensis, was later shown to be based on teeth from a spinosaurid theropod dinosaur....
- Family RhomaleosauridaeRhomaleosauridaeRhomaleosauridae is a family of extinct reptiles in the Plesiosauria order. It includes the Macroplata, Maresaurus, Rhomaleosaurus, Yuzhoupliosaurus and Meyerasaurus genera....
- ArchaeonectrusArchaeonectrusArchaeonectrus is an extinct genus of pliosaur from the Jurassic of what is now southeastern England. The type species is Archaeonectrus rostratus, first named by Sir Richard Owen in 1865, and renamed by N.I. Novozhilov 99 years later.-References:* Sepkoski, J.J. . "A compendium of fossil marine...
- BorealonectesBorealonectesBorealonectes is a genus of rhomaleosaurid pliosauroid, a type of plesiosaur. Its fossils were found in the Callovian-age Hiccles Cove Formation of Melville Island, Canada, one of the islands in the Canadian Arctic Archipelago. It is based on a skull, neck vertebrae, and the right forelimb of...
- ? BishanopliosaurusBishanopliosaurusBishanopliosaurus is a genus of plesiosaur. The type species is B. youngi, based on remains found in the Ziliujing formation of China....
- EurycleidusEurycleidusEurycleidus is an extinct genus of plesiosaur. The type species is E. arcuatus, which lived during the Hettangian age . Like other plesiosaurs, Eurycleidus probably lived on a diet of fish, using its sharp needle-like teeth to catch prey. Its shoulder bones were fairly large, indicating a powerful...
- ? HexatarsostinusHexatarsostinusHexatarsostinus is an extinct genus of plesiosaur....
- MacroplataMacroplataMacroplata , meaning, , is an extinct genus of Early Jurassic basal plesiosaur which grew up to in length. Like other plesiosaurs, Macroplata probably lived on a diet of fish, using its sharp needle-like teeth to catch prey. Its shoulder bones were fairly large, indicating a powerful forward...
- MaresaurusMaresaurusMaresaurus is an extinct genus of pliosaur from the Middle Jurassic of what is now Argentina. The type species, Maresaurus coccai, was named by Gasparini in 1997. Recent phylogenetic analysis found Maresaurus to be a rhomaleosaurid ....
- RhomaleosaurusRhomaleosaurusRhomaleosaurus is an extinct genus of Early Jurassic rhomaleosaurid pliosauroid known from Northamptonshire and from Yorkshire of the United Kingdom. It was first named by Harry Seeley in 1874 and the type species is Rhomaleosaurus cramptoni...
- MeyerasaurusMeyerasaurusMeyerasaurus is an extinct genus of rhomaleosaurid known from Holzmaden, Baden-Württemberg of southeastern Germany.-Description:Meyerasaurus is known from the holotype SMNS 12478, articulated and complete skeleton which preserved the skull, exposed in ventral view. The skull has a length of ,...
- SthenarosaurusSthenarosaurusSthenarosaurus is an extinct genus of plesiosaur....
- ? YuzhoupliosaurusYuzhoupliosaurusYuzhoupliosaurus is an extinct genus of plesiosaur from the Middle Jurassic of China. The genus is known only from a lower jaw, a vertebra, and fragments of a pectoral girdle...
- Archaeonectrus
- Family PliosauridaePliosauridaePliosauridae is a family of pliosauroid plesiosaurs from the Earliest Jurassic to the early Late Cretaceous of Australia, Europe, North America and South America. It was formally named by Harry G...
- AttenborosaurusAttenborosaurusAttenborosaurus is an extinct genus of plesiosaur from the Early Jurassic of Dorset, England. The type species is A. conybeari.The genus is named after David Attenborough, the species after William Conybeare.-Sources:...
- GallardosaurusGallardosaurusGallardosaurus is a genus of pliosaurid plesiosaur from the Caribbean seaway. It contains the single species Gallardosaurus iturraldei. Gallardosaurus was found in middle-late Oxfordian-age rocks of the Jagua Formation of western Cuba...
- HauffiosaurusHauffiosaurusHauffiosaurus is an extinct genus of Early Jurassic pliosaurid plesiosaur known from Holzmaden of Germany and from Yorkshire of the United Kingdom. It was first named by Frank Robin O’Keefe in 2001 and the type species is Hauffiosaurus zanoni. In 2011, two additional species were assigned to this...
- Marmornectes
- LiopleurodonLiopleurodonLiopleurodon is a genus of large, carnivorous marine reptile belonging to the Pliosauroidea, a clade of short-necked plesiosaurs. Two species of Liopleurodon lived during the Callovian stage of the Middle Jurassic Period , while the third, L. rossicus, lived during the Late Jurassic...
- PeloneustesPeloneustesPeloneustes is an extinct genus of sauropterygian reptile belonging to the family Pliosauridae. It is known from the Callovian aged deposits of the Oxford clay formation of England...
- PliosaurusPliosaurusPliosaurus is a genus of extinct marine reptile. It is included in the family Pliosauridae. Its diet would have included fish, squid and other marine reptiles. This genus has contained several species in the past but it currently consists of the type species P. brachydeirus, P. macromerus and P...
- ? PolyptychodonPolyptychodonPolyptychodon is an extinct genus of sauropterygian reptile belonging to the family Pliosauridae that lived during the Cretaceous. Its fossils have been found in Europe and North America....
- SimolestesSimolestesSimolestes is an extinct genus of pliosaurs that lived in the Middle to Late Jurassic. Three species are currently known:*Simolestes keileni from the Bajocian of France...
- ThalassiodraconThalassiodraconThalassiodracon is an extinct genus of small pliosaur that lived in the Late Triassic to the Early Jurassic of Europe. The animal is known from a number of complete skeletons found by the fossil collector Thomas Hawkins in Somerset, England...
- Subfamily Brachaucheninae
- BrachaucheniusBrachaucheniusBrachauchenius is an extinct genus of pliosaur that lived in America during the Cretaceous.The type species, Brachauchenius lucasi, lived in the Western Inland Sea of North America around 93.5-89.3 million years ago, during the Turonian stage of the Cretaceous...
- KronosaurusKronosaurusKronosaurus is an extinct genus of short-necked pliosaur. It was among the largest pliosaurs, and is named after the leader of the Greek Titans, Cronus.-Discovery and species:Kronosaurus lived in the Early Cretaceous Period ....
- Brachauchenius
- Attenborosaurus
- ? Megalneusaurus
Phylogeny
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
below follows a 2011 analysis by paleontologists Hilary F. Ketchum and Roger B. J. Benson, and reduced to genera only.
Large pliosauroids
The discovery of a very large pliosauroid was announced in 2002, from MexicoMexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. This pliosauroid came to be known as the "Monster of Aramberri". The size of this specimen has been estimated to be about 15 metres (49.2 ft) long and it had a 3 metres (10 ft) long skull. Consequently, although widely reported as such, it does not belong to the genus Liopleurodon. The remains of this animal, consisting of a partial vertebral column, were dated to the Kimmeridgian
Kimmeridgian
In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma . The Kimmeridgian follows the Oxfordian and precedes the Tithonian....
of the La Caja Formation. The fossils were found much earlier, in 1985, by a geology student and were at first erroneously attributed to a theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
by Hahnel. The remains originally contained part of a rostrum with teeth (now lost).
In August 2006, palaeontologists of the University of Oslo discovered the first remains of a pliosaur on Norwegian soil. The remains were described as "very well preserved as well as being unique in their completeness" and are the first complete skeleton of a pliosaur ever discovered. Whether it belongs to the genus Pliosaurus or Liopleurodon awaits publication of the fossil description. In the summer of 2008, the fossil remains of the huge pliosaur were dug up from the permafrost on Svalbard
Svalbard
Svalbard is an archipelago in the Arctic, constituting the northernmost part of Norway. It is located north of mainland Europe, midway between mainland Norway and the North Pole. The group of islands range from 74° to 81° north latitude , and from 10° to 35° east longitude. Spitsbergen is the...
, a Norwegian island close to the North Pole
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...
. The excavation of the find is documented in the 2009 History television special Predator X
Predator X (TV program)
Predator X is a 2009 television special on the cable television channel History. The show documents the excavation of a giant pliosaur on an island in the Norwegian Svalbard archipelago. The special follows Dr...
.
On 26 October 2009 palaeontologists reported the discovery of potentially the largest pliosauroid yet found, discovered in cliffs near Weymouth, Dorset
Dorset
Dorset , is a county in South West England on the English Channel coast. The county town is Dorchester which is situated in the south. The Hampshire towns of Bournemouth and Christchurch joined the county with the reorganisation of local government in 1974...
, on Britain's Jurassic coast
Jurassic Coast
The Jurassic Coast is a World Heritage Site on the English Channel coast of southern England. The site stretches from Orcombe Point near Exmouth in East Devon to Old Harry Rocks near Swanage in East Dorset, a distance of ....
. The fossil had a skull length of 2.4 metres (7.9 ft) and a body length of 16 metres (52.5 ft). Palaeontologist Richard Forrest told the BBC: "I had heard rumours that something big was turning up. But seeing this thing in the flesh, so to speak, is just jaw dropping. It is simply enormous."