Plesiosaurs were marine reptiles, not dinosaurs. The first complete skeleton was discovered in 1823 by pioneering paleontologist Mary Anning, in Jurassic age rocks at Lyme Regis in England.
The second photo is for fun, showing the plesiosaur with a tiny fossil ichthyosaur vertebra from Lyme Regis. Plesiosaurs and ichthyosaurs (another marine reptile) co-existed in the Jurassic, and the find of a plesiosaur with infant ichthyosaur remains in its stomach was reported from Wyoming in 2009.
This miniature model is laser cut in the USA and meticulously assembled by me.
1 15/16 inches (4.9 cm) nose to tail, 1 1/4 inches (3.2 cm) deep and 1 1/2 inches (3.8 cm) tall.