Pachypleurosaurus is a genus of pachypleurosaurian that lived during the Triassic Period. It was a basal sauropterygian, and had a long neck. The type species is P. edwardsi.
More real-life information: Pachypleurosaurus.
Pachypleurosaurus has never appeared or mentioned in any Jurassic Park films or books, it has however appeared in Jurassic Park III: Park Builder.