calum'sfossils
Plesiosauroidea sp specimen 1 angle 1
Age: 150-160Ma
Oxfordian to Kimmeridgian Age
Late Jurassic Epoch
Jurassic Period
Mesozoic Era - Dinosaur times
Location: Yorkshire Coast
Filey Bay
Reighton
Rock Type: Mudstone likely of Ampthill or Kimmeridge Clay Formations
Specimen:
An amphicoelous (both anterior and posterior sides are concave) vertebral body. Such vertebrae are adapted to allow for a degree of flexibility and articulation that is particularly beneficial in an aquatic environment. This structural adaptation helps to streamline the body and facilitate efficient, undulating movements through water. Amphicolous vertebrae have therefore convergently evolved multiple times, such as in both fish and marine reptiles. This is from a plesiosaur according to a visit to Manchester Museum due to the more angular, almost triangular shape, rather than more rounded and coin-like such as in ichthyosaurs apparently. Also generally thicker than a thin ichthyosaur vertebrae.
Species:
Plesiosauroidea (from Greek plēsios, meaning 'near' or 'close to', and sauros, meaning 'lizard') is an extinct clade of carnivorous marine reptiles. They are notable for having the longest neck-to-body ratio of any reptile, with their snake-like necks being a defining feature. Plesiosauroids lived during the Jurassic and Cretaceous periods, first appearing in the Early Jurassic (late Sinemurian stage) and thriving until the mass extinction event at the end of the Cretaceous Period (K-Pg extinction). Although they coexisted with dinosaurs in the Mesozoic era, plesiosauroids were not dinosaurs but rather diapsid reptiles.
The first complete plesiosauroid skeletons were discovered in England by Mary Anning in the early 19th century, making them some of the earliest fossil vertebrates described by science. Plesiosauroids had broad bodies, short tails, and retained two pairs of limbs that evolved into large flippers, which were key to their marine lifestyle. Fossil evidence also frequently includes gastroliths (gut stones), which were likely used to aid digestion or balance in the water.
Recent studies of their teeth have suggested that plesiosauroids, along with other marine reptiles, had a warm-blooded (endothermic) metabolism similar to that of mammals, allowing them to survive in colder waters. Unlike their faster-swimming relatives, the pliosaurs, most plesiosauroids (except for members of the Polycotylidae family) were likely slow swimmers. It is believed they cruised beneath the surface of the water, using their long necks to snap up fish and cephalopods. Their four-flipper swimming adaptation gave them exceptional maneuverability, allowing them to rotate and change direction quickly to catch prey.
Contrary to many artistic reconstructions, plesiosauroids could not lift their heads and necks above the water in a swan-like pose. Even if their necks had the flexibility for such a movement (which they did not), the weight of their neck would have caused their bodies to tip forward, keeping most of the neck submerged.
One significant discovery related to plesiosaur reproduction was made on 12 August 2011, when U.S. researchers described a fossil of a pregnant plesiosaur (Polycotylus latippinus) found in Kansas. This fossil confirmed that plesiosauroids gave birth to a single, large live offspring, contrasting with other marine reptiles that typically gave birth to multiple smaller young. This finding also dispelled previous theories suggesting plesiosauroids crawled onto land to lay eggs, as their anatomy made terrestrial movement unlikely.
Plesiosauroids varied in size depending on the species. Adult individuals, such as those known from near Yorkshire, typically ranged from 3 to 7 meters in length.
Reptiles, as traditionally defined, are a group of tetrapods that typically have ectothermic ('cold-blooded') metabolisms and develop through amniotic eggs. However, modern taxonomy, based on genetic and paleontological evidence, considers reptiles a paraphyletic group. This is because birds (class Aves), which evolved from dinosaurs, are more closely related to crocodilians than to other reptiles. Therefore, birds are often included within the reptilian group in many cladistic systems, redefining Reptilia as a monophyletic clade that includes both birds and reptiles. The exact definition of this clade varies among scientists, with some preferring the term Sauropsida to encompass all amniotes more closely related to reptiles than to mammals.
The earliest proto-reptiles appeared in the Carboniferous period, evolving from reptiliomorph tetrapods that were increasingly adapted to life on land. In addition to modern reptiles, there were many now-extinct groups, some of which disappeared during mass extinction events, such as the Cretaceous–Paleogene extinction. This event wiped out pterosaurs, plesiosaurs, and all non-avian dinosaurs, along with many species of crocodilians and squamates like mosasaurs. Reptiles are tetrapod vertebrates, meaning they either have four limbs or descended from ancestors that did. Unlike amphibians, reptiles do not undergo an aquatic larval stage. Most are oviparous (egg-laying), but some squamates are viviparous, with embryos developing inside the mother, nourished by a placenta rather than enclosed in eggshells.
As amniotes, reptile eggs are protected by membranes, enabling reproduction on dry land. Some viviparous reptiles have placentas analogous to those of mammals and provide initial care to their young. The earliest amniotes, including stem-reptiles, were relatively small and inconspicuous compared to larger tetrapods like Cochleosaurus. However, during the Carboniferous Rainforest Collapse, primitive tetrapods were devastated, while stem-reptiles thrived in the drier conditions. Unlike amphibians, which required water for reproduction, early reptiles could lay their shelled eggs on land, giving them an advantage in the new environment. As a result, amniotes rapidly diversified, adopting new feeding strategies, including herbivory and carnivory, and outcompeting primitive tetrapods.
The dominance of reptiles in terrestrial ecosystems set the stage for the Mesozoic era, also known as the 'Age of Reptiles'. A 2021 study of reptile diversity during the Carboniferous and Permian periods revealed a higher level of diversity than previously thought, comparable to or even exceeding that of synapsids. This period has been proposed as the 'First Age of Reptiles.' The Permian–Triassic extinction event, the most significant mass extinction in Earth's history, caused a prolonged die-off, eliminating most of the earlier parareptile and synapsid megafauna. True reptiles, particularly archosauromorphs, survived and thrived, characterized by elongated hind legs and an upright posture. These early archosaurs eventually gave rise to the dinosaurs and pterosaurs, as well as the ancestors of modern crocodiles.
During the Triassic period, archosaurs became the dominant group, evolving into the dinosaurs and smaller theropods, which later gave rise to birds. The sister group to archosaurs is Lepidosauromorpha, which includes lizards, tuataras, and their fossil relatives. Mosasaurs, one of the major groups of Mesozoic marine reptiles, belong to this clade. Other marine reptiles, such as ichthyosaurs and sauropterygians, evolved during the early Triassic, but their exact phylogenetic placement remains debated. Some researchers link them to lepidosauromorphs, while others associate them with archosauromorphs or classify them as diapsids outside these two groups.
The close of the Cretaceous period saw the extinction of many Mesozoic reptilian megafauna during the Cretaceous–Paleogene extinction event. Large marine reptiles, except for sea turtles, perished, and only semi-aquatic crocodiles and the lizard-like choristoderes, which later became extinct in the Miocene, survived. Of the dinosaurs, only small beaked birds survived this mass extinction, which marked the end of the Mesozoic and the rise of the Cenozoic era. In the aftermath, mammals and birds rapidly diversified, filling the ecological niches left by extinct reptiles. While reptile diversification slowed, they remained key components of the megafauna, especially in the form of large tortoises. Though mammals and birds came to
Plesiosauroidea sp specimen 1 angle 1
Age: 150-160Ma
Oxfordian to Kimmeridgian Age
Late Jurassic Epoch
Jurassic Period
Mesozoic Era - Dinosaur times
Location: Yorkshire Coast
Filey Bay
Reighton
Rock Type: Mudstone likely of Ampthill or Kimmeridge Clay Formations
Specimen:
An amphicoelous (both anterior and posterior sides are concave) vertebral body. Such vertebrae are adapted to allow for a degree of flexibility and articulation that is particularly beneficial in an aquatic environment. This structural adaptation helps to streamline the body and facilitate efficient, undulating movements through water. Amphicolous vertebrae have therefore convergently evolved multiple times, such as in both fish and marine reptiles. This is from a plesiosaur according to a visit to Manchester Museum due to the more angular, almost triangular shape, rather than more rounded and coin-like such as in ichthyosaurs apparently. Also generally thicker than a thin ichthyosaur vertebrae.
Species:
Plesiosauroidea (from Greek plēsios, meaning 'near' or 'close to', and sauros, meaning 'lizard') is an extinct clade of carnivorous marine reptiles. They are notable for having the longest neck-to-body ratio of any reptile, with their snake-like necks being a defining feature. Plesiosauroids lived during the Jurassic and Cretaceous periods, first appearing in the Early Jurassic (late Sinemurian stage) and thriving until the mass extinction event at the end of the Cretaceous Period (K-Pg extinction). Although they coexisted with dinosaurs in the Mesozoic era, plesiosauroids were not dinosaurs but rather diapsid reptiles.
The first complete plesiosauroid skeletons were discovered in England by Mary Anning in the early 19th century, making them some of the earliest fossil vertebrates described by science. Plesiosauroids had broad bodies, short tails, and retained two pairs of limbs that evolved into large flippers, which were key to their marine lifestyle. Fossil evidence also frequently includes gastroliths (gut stones), which were likely used to aid digestion or balance in the water.
Recent studies of their teeth have suggested that plesiosauroids, along with other marine reptiles, had a warm-blooded (endothermic) metabolism similar to that of mammals, allowing them to survive in colder waters. Unlike their faster-swimming relatives, the pliosaurs, most plesiosauroids (except for members of the Polycotylidae family) were likely slow swimmers. It is believed they cruised beneath the surface of the water, using their long necks to snap up fish and cephalopods. Their four-flipper swimming adaptation gave them exceptional maneuverability, allowing them to rotate and change direction quickly to catch prey.
Contrary to many artistic reconstructions, plesiosauroids could not lift their heads and necks above the water in a swan-like pose. Even if their necks had the flexibility for such a movement (which they did not), the weight of their neck would have caused their bodies to tip forward, keeping most of the neck submerged.
One significant discovery related to plesiosaur reproduction was made on 12 August 2011, when U.S. researchers described a fossil of a pregnant plesiosaur (Polycotylus latippinus) found in Kansas. This fossil confirmed that plesiosauroids gave birth to a single, large live offspring, contrasting with other marine reptiles that typically gave birth to multiple smaller young. This finding also dispelled previous theories suggesting plesiosauroids crawled onto land to lay eggs, as their anatomy made terrestrial movement unlikely.
Plesiosauroids varied in size depending on the species. Adult individuals, such as those known from near Yorkshire, typically ranged from 3 to 7 meters in length.
Reptiles, as traditionally defined, are a group of tetrapods that typically have ectothermic ('cold-blooded') metabolisms and develop through amniotic eggs. However, modern taxonomy, based on genetic and paleontological evidence, considers reptiles a paraphyletic group. This is because birds (class Aves), which evolved from dinosaurs, are more closely related to crocodilians than to other reptiles. Therefore, birds are often included within the reptilian group in many cladistic systems, redefining Reptilia as a monophyletic clade that includes both birds and reptiles. The exact definition of this clade varies among scientists, with some preferring the term Sauropsida to encompass all amniotes more closely related to reptiles than to mammals.
The earliest proto-reptiles appeared in the Carboniferous period, evolving from reptiliomorph tetrapods that were increasingly adapted to life on land. In addition to modern reptiles, there were many now-extinct groups, some of which disappeared during mass extinction events, such as the Cretaceous–Paleogene extinction. This event wiped out pterosaurs, plesiosaurs, and all non-avian dinosaurs, along with many species of crocodilians and squamates like mosasaurs. Reptiles are tetrapod vertebrates, meaning they either have four limbs or descended from ancestors that did. Unlike amphibians, reptiles do not undergo an aquatic larval stage. Most are oviparous (egg-laying), but some squamates are viviparous, with embryos developing inside the mother, nourished by a placenta rather than enclosed in eggshells.
As amniotes, reptile eggs are protected by membranes, enabling reproduction on dry land. Some viviparous reptiles have placentas analogous to those of mammals and provide initial care to their young. The earliest amniotes, including stem-reptiles, were relatively small and inconspicuous compared to larger tetrapods like Cochleosaurus. However, during the Carboniferous Rainforest Collapse, primitive tetrapods were devastated, while stem-reptiles thrived in the drier conditions. Unlike amphibians, which required water for reproduction, early reptiles could lay their shelled eggs on land, giving them an advantage in the new environment. As a result, amniotes rapidly diversified, adopting new feeding strategies, including herbivory and carnivory, and outcompeting primitive tetrapods.
The dominance of reptiles in terrestrial ecosystems set the stage for the Mesozoic era, also known as the 'Age of Reptiles'. A 2021 study of reptile diversity during the Carboniferous and Permian periods revealed a higher level of diversity than previously thought, comparable to or even exceeding that of synapsids. This period has been proposed as the 'First Age of Reptiles.' The Permian–Triassic extinction event, the most significant mass extinction in Earth's history, caused a prolonged die-off, eliminating most of the earlier parareptile and synapsid megafauna. True reptiles, particularly archosauromorphs, survived and thrived, characterized by elongated hind legs and an upright posture. These early archosaurs eventually gave rise to the dinosaurs and pterosaurs, as well as the ancestors of modern crocodiles.
During the Triassic period, archosaurs became the dominant group, evolving into the dinosaurs and smaller theropods, which later gave rise to birds. The sister group to archosaurs is Lepidosauromorpha, which includes lizards, tuataras, and their fossil relatives. Mosasaurs, one of the major groups of Mesozoic marine reptiles, belong to this clade. Other marine reptiles, such as ichthyosaurs and sauropterygians, evolved during the early Triassic, but their exact phylogenetic placement remains debated. Some researchers link them to lepidosauromorphs, while others associate them with archosauromorphs or classify them as diapsids outside these two groups.
The close of the Cretaceous period saw the extinction of many Mesozoic reptilian megafauna during the Cretaceous–Paleogene extinction event. Large marine reptiles, except for sea turtles, perished, and only semi-aquatic crocodiles and the lizard-like choristoderes, which later became extinct in the Miocene, survived. Of the dinosaurs, only small beaked birds survived this mass extinction, which marked the end of the Mesozoic and the rise of the Cenozoic era. In the aftermath, mammals and birds rapidly diversified, filling the ecological niches left by extinct reptiles. While reptile diversification slowed, they remained key components of the megafauna, especially in the form of large tortoises. Though mammals and birds came to