They were building a complex of houses and they ran into the fossil remains of a 150 million-year-old marine predator.

A mechanical engineer passionate about paleontology stumbled upon something extraordinary as he searched for shark teeth in a land destined for home construction. Steve Schliesing visited a site in Celina, Texas last November, when he came to the discovery of fossilized bones of a plesiosaur, a marine reptile that dominated the seas during the Jurassic period. The finding occurred on land where modern suburban houses are now erected, an area tha…