Plesiosaurus dolichodeirus, an extinct marine reptile from the Early Jurassic period, was characterized by a long neck, small head, and broad, paddle-like limbs. It inhabited shallow seas and likely hunted fish using its speed and agility.

Plesiosaurus dolichodeirus, an extinct marine reptile, was primarily found in what is now Europe. Fossils have been discovered in regions that were once part of the ancient sea known as the Tethys Ocean, specifically in areas corresponding to modern-day England and parts of continental Europe.

Plesiosaurus dolichodeirus inhabited marine environments during the Early Jurassic period, approximately 183 to 200 million years ago. These environments were characterized by warm, shallow seas that covered much of Europe. The climate during this period was generally warmer than today, with higher sea levels and widespread epicontinental seas.

Plesiosaurus dolichodeirus was a carnivorous marine reptile that occupied a niche as a predator in the marine ecosystem. It likely preyed upon fish and other marine organisms, utilizing its long neck to catch prey in the water. Its morphology suggests it was adapted to swimming in open waters, where it could use its flippers for propulsion and maneuverability.