Fossil Plesiosaur Humerus Bone, from the Jurassic Coast of England
This piece is not for sale.
Age: 185 Million Years Old (Jurassic Period)
Location: Charmouth Beach, near Golden Cap, UK
This is a fossil Plesiosaur humerus bone I found near Golden Cap in Charmout/Bridport, UK on New Years Day, 2019.
ThePlesiosauriaorplesiosaursare anorderorcladeof extinctMesozoicmarine reptiles(marineSauropsida), belonging to theSauropterygia.
Plesiosaurs first appeared in the latestTriassicPeriod, possibly in theRhaetianstage, about 203 million years ago.They became especially common during theJurassicPeriod, thriving until their disappearance due to theCretaceous–Paleogene extinction eventat the end of theCretaceousPeriod, about 66 million years ago. They had a worldwide oceanic distribution.
Plesiosaurs were among the first fossil reptiles discovered. In the beginning of the nineteenth century, scientists realised how distinctive their build was and they were named as a separate order in 1835. The first plesiosaurian genus, the eponymousPlesiosaurus, was named in 1821.
The first complete skeleton of Plesiosaurus was discovered by early paleontologist and fossil hunterMary Anningin Sinemurian (Early Jurassic)-age rocks of the lower Lias Group in December 1823, near where this humerus bone was found.
Since then, more than a hundred valid species have been described. In the early twenty-first century, the number of discoveries has increased, leading to an improved understanding of their anatomy, relationships and way of life.
Plesiosaurs had a broad flat body and a short tail. Their limbs had evolved into four long flippers, which were powered by strong muscles attached to wide bony plates formed by the shoulder girdle and the pelvis. The flippers made a flying movement through the water. Plesiosaurs breathed air, and bore live young; there are indications that they were warm-blooded.
Plesiosaurs showed two mainmorphologicaltypes. Some species, with the "plesiosauromorph" build, had (sometimes extremely) long necks and small heads; these were relatively slow and caught small sea animals. Other species, some of them reaching a length of up to seventeen metres, had the "pliosauromorph" build with a short neck and a large head; these wereapex predators, fast hunters of large prey. The two types are related to the traditional strict division of the Plesiosauria into two suborders, the long-neckedPlesiosauroideaand the short-neckPliosauroidea. Modern research, however, indicates that several "long-necked" groups might have had some short-necked members or vice versa. Therefore, the purely descriptive terms "plesiosauromorph" and "pliosauromorph" have been introduced, which do not imply a direct relationship. "Plesiosauroidea" and "Pliosauroidea" today have a more limited meaning. The term "plesiosaur" is properly used to refer to the Plesiosauria as a whole, but informally it is sometimes meant to indicate only the long-necked forms, the old Plesiosauroidea.