Fossil Plesiosaur Humerus/ Jurassic/ Dorset, England
Ships from Massachusetts!
Age: 160 Million Years Ild
Location: Kimmeridge Bay, Dorset, England
Plesiosaurs first appeared in the latest Triassic Period, possibly in the stage, about 203 million years ago. They became especially common during the Jurassic Period, thriving until their disappearance due to the Cretaceous–Paleogene extinction event at the end of the Cretaceous Period, 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 eponymous Plesiosaurus, was named in 1821. 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.
The first complete skeleton of Plesiosaurus was discovered by early paleontologist and fossil hunter Mary Anning in Sinemurian (Early Jurassic)-age rocks of the lower Lias Group in December 1823. Additional fossils of Plesiosaurus were found in rocks of the Lias Group of Dorset for many years, "until the cessation of quarrying activities in the Lias Group, early in this [20th] century."
Plesiosaurus, the species (as Plesiosaur is the family) was one of the first of the "antediluvian Reptiles” to be discovered and excited great interest in Victorian England. It was so-named ("near lizard") by William Conybeare and Henry De la Beche, to indicate that it was more like a normal reptile than Ichthyosaurus, which had been found in the same rock strata just a few years earlier. Plesiosaurus is the archetypical genus of Plesiosauria and the first to be described, hence lending its name to the order. Conybeare and De la Beche coined the name for scattered finds from the Bristol region, Dorset, and Lyme Regis in 1821. The type species of Plesiosaurus, P. dolichodeirus, was named and described by Conybeare in 1824 on the basis of Anning's original finds.