Carroll, Robert L. Redpath Museum, McGill University, Montreal, Quebec, Canada.
- Links to Primary Literature
- Additional Readings
An order of extinct aquatic diapsid reptiles within the infraclass Sauropterygia, common throughout the world during the Jurassic and Cretaceous periods. These large carnivores are characterized by long, paddle-shaped limbs and short, dorsoventrally compressed bodies (see illustration). In contrast with nothosaurs (more primitive members of the Sauropterygia), plesiosaurs have greatly expanded ventral portions of both pectoral and pelvic girdles to provide large areas for the attachment of muscles to move the limbs anteriorly and posteriorly. Lateral undulation of the trunk was severely restricted by elaboration of the ventral scales. The great length of the limbs indicates that they must have been used symmetrically, rather than alternatively as in primitive reptiles. The configuration of the skeleton suggests that plesiosaurs swam in the manner of sea lions by horizontal retraction of the limbs, rather than like sea turtles and penguins which use the limbs like wings to fly through the water.
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Its dedicated editorial team is led by Sagan Award winner John Rennie. Contributors include more than 9000 highly qualified scientists and 39 Nobel Prize winners.
MORE THAN 8500 articles and Research Reviews covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 17,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information