This genus of pliosaurid plesiosaur were marine reptiles and the fossil remains were discovered in Peterborough, part of the Oxford Clay Formation of the Callovian age in England. Known to have lived in the Middle Jurassic period, the Peloneustes was primarily described by Harry Govier Seeley in 1896 but was previously put into its own genus by Richard Lydekker, a well-known naturalist in 1889. This reptile species is known from many specimens of which more are complete. The fossil material or remains collected so far consists of teeth, multiple vertebrae, a partial mandible, and most of the limbs. A published description of this genus from reptilia classification came out in 1889 when Lydekker recognized this specimen as an individual of the Plesiosaurus philarchus (P. philarchus). Suggested by many scientists and paleontologists to be closely related to the Plesiosaur, they were not as large as a Pliosaurid but they had quite a streamlined body. This would have allowed them to swim in an open range like wide oceans and seas as well as to great depths. Like many other pliosaurs, this aquatic creature that lived way back in history also lived alongside dinosaurs.
Similar to their relatives in appearance, these Mesozoic reptiles had short necks and jaws that made it easy to catch almost any kind of prey. Their diet was largely piscivorous so they probably fed on a variety of small fish, squid, shrimps, crustaceans, and abalones. Data has revealed more precisely that they fed on hard prey like ammonites and the streamlined shape of their body also made it easy to chase certain fast prey like belemnites.
The Pleneustes species does not come under the category of dinosaurs. They were sea reptiles that mostly stayed in the water, probably coming onto land only for the purpose of giving birth.
The name Peloneustes is pronounced as 'Pel-o-new-steez'. The name means 'mud swimmer'. They were first described by Harry Govier Seeley in 1896 and were believed to have lived about 160-165 million years ago in the Callovian age of the Middle Jurassic in England.
These marine reptiles were a type of Plesiosaurus species. They were in fact closely related to them in appearance and behavior. Being a smaller representative of the Plisauridae group, they had few blunt teeth, a short neck, and long, strong jaws which enabled them to feed on large prey.
The Peloneustes was known to have inhabited the Earth during the Callovian age of the Middle Jurassic period, about 160-165 million years ago. The fossil remains of these specimens were discovered in the Oxford Clay Formation in England. Harry Govier Seeley, in 1892, grouped the Peloneustes and Pliosaurus together instead of placing them in separate genera since he stated that there weren't many differences between the two.
The Peloneustes became extinct about 66 million years ago, just like its close relative, the Plesiosaur. Many almost complete fossil specimens of the Peloneustes have been collected in other countries like Germany and France too. They consist of the teeth, a mandible, ribs, vertebrates, and paddle bones.
The Peloneustes lived in the ocean and at times, in estuaries and shorelines. These reptile specimens found from the Oxford Clay Formation in England had a piscivorous diet often feeding on prey like fish, shrimp, squid, crustaceans, ammonites, and belemnites.
These Mesozoic marine reptiles, that lived in the Callovian age of the Middle Jurassic in England and some parts of Germany and France, made their homes in open oceans, seas, shorelines of lakes, and estuaries. Living in these habitats made it easy for them to also have access to small and large prey. They were known to have a specific liking for ammonites and belemnites, cracking the hard shell with their blunt teeth and easily eating the mollusk within.
There is very little known about whether these Mesozoic extinct marine animals lived in groups or not. However, there is a speculation that they would have moved in small groups since they were also a genus of plesiosaurs and come from the Pliosauridae family. It is also believed by many scientists that they shared their waters with Liopleurodons.
Since they were a type of plesiosaur species, they were believed to have evolved from warm-bloodedness and moved into open oceans and shallow waters. They lived a life without facing any threats and would have been around for a very long time, although the exact number of years is not known at the moment.
These Mesozoic marine reptiles of the Pliosauridae family reproduced just like how a plesiosaur did. They were viviparous and gave birth to live young! This was proven to be true when a group of scientists found evidence in the 78 million-year-old fossil material of a pregnant female plesiosaur. They have also mentioned that instead of laying a number of eggs, they gave birth to just one live baby. They would have been nurturing parents, although speculative, and would have fed the baby at regular intervals to ensure it was healthy. They would have also protected them since the young of this species were a target prey for many large predators.
This Mesozoic 'mud swimmer' or marine reptile of the Animalia kingdom lived during the Callovian age of the Middle Jurassic. Named Peloneustes philarchus (P. philarchus), their fossil remains were first discovered in the Oxford Clay Formation of England. Seeley first described them as a species of Plesiosaurus since they were hardly any differences between the two genera. Previously, Richard Lydekker put them in their own genus. The genus Peloneustes was very similar in appearance to its close relative, the Plesiosaur. Peloneustes, like many pliosaurs, displayed a diminished level of ossification in their bones. The skulls of these marine reptiles were triangular in shape and large.
It had four flat, paddle-like limbs which allowed it to move swiftly in shallow and open waters, and also had a greatly streamlined body. This streamlined body with a short, broad tail would have also contributed to their quickness in water when chasing fast prey. They had short necks and strong jaws filled with a few blunt teeth. These teeth made cutting into the carcasses of prey easy. This was accepted as true by many researchers since this marine species of the Pliosauridae family often fed on ammonites and belemnites, tearing open the hard shell on the outside and eating the soft mollusk found on the inside. Peloneustes philarchus (P. philarchus) species was also known to have shared its habitat with Liopleurodon.
The number of bones that this species of the Reptilia classification had is not available due to the lack of data and evidence. However, being pliosaurs, they would have definitely had over 200 bones in total!
These Mesozoic 'mud swimmers' with blunt teeth from the Pliosauridae group depended on sound to communicate when in water. Echolocation is a technique used by certain animals to detect the location of certain objects in the environment by reflecting sound and this would have been utilized by this marine specimen. This would have allowed them to detect enemies, prey, objects and also aid in navigating through their water habitats.
The Peloneustes, that lived in the Callovian age of the middle Jurassic period, was not very large in length and height. Found in the Oxford Clay Formation in England, this specimen was about 137.7 in (3.4 m) in length, the same as a wandering albatross!
There is no sufficient data to establish the exact speed at which the Peloneustes philarchus (P. philarchus) moved in the water. They could have possibly moved at about 5.6 mph (9 kph), just like a tiger beetle!
The Peloneustes specimen weighed about 1102.3 lb (500 kg). The weight of this 'mud swimmer' from the Reptilia classification is similar to that of a moose! They were not large in size, being a member of the pliosaurid group.
There are no specific male or female names for this marine reptile species with blunt teeth, whose remains were found in the Oxford Clay Formation in England. They simply go by their common name which is Peloneustes or otherwise, Peloneustes philarchus (P. philarchus).
A baby Peloneustes is called a hatchling or nestling!
The dinosaurs in this species were piscivores. This meant that they fed on various other small and large sea prey like fish, shrimp, crustaceans, and squid. They had a specific liking for ammonites and belemnites as their blunt teeth made it easy to break open the tough shells and eat the soft mollusk inside.
Again, not much data is available on this topic but they were known to be quite social in their behavior and calm as well. Nonetheless, like every creature in the world and throughout history, they would have shown a certain level of aggression when either threatened or put in harm's way.
The paddle-like limbs of this sea specimen that lived in the Callovian middle Jurassic are very similar to those seen in the modern-day penguin!
Geologist Henry Porter discovered the first-ever fossil remains of this specimen of Callovian middle Jurassic near the clay pit which was close to Peterborough, England. This specimen was then described for the first time by Seeley in 1896 who grouped the Peloneustes species and Plesiosaurs as one instead of separate genera since the similarities between the two were vast. Before this, Richard Lydekker had described it to be distinct in its own genus. Some fossil remains of this specimen have also been found in another location which is the Cretaceous of Germany.
The Peloneustes name means 'mud swimmer'. They are also called a 'mud swimmer'.
Here at Kidadl, we have carefully created lots of interesting family-friendly prehistoric animal facts for everyone to discover! Learn more about some other creatures from our Macroplata facts or Kaiwhekea facts for kids.
You can even occupy yourself at home by coloring in one of our free printable Peloneustes coloring pages.
Main image by Nobu Tamara
Second image by Nobu Tamara