Warm-blooded reptiles?

Modern reptiles are cold blooded, but what about extinct reptiles?
Based on their teeth, large extinct swimming reptiles, like ichthyosaurs, plesiosaurs, and mosasaurs are thought to have been predators in the Mesozoic oceans. Their streamlined body profile also suggests an active lifestyle. An active lifestyle requires high metabolic rates, which are usually correlated with at least some ability to regulate body temperature.
Scientists analyzed oxygen isotopes from the teeth of these extinct marine reptiles and compared the values with those from cold-blooded fossil fish. The results showed ichthyosaurs and plesiosaurs differed significantly from fish, and suggest that these two reptiles, both of whom were active, "pursuit predators", probably controlled their body temperature. The data for mosasaurs were equivocal and suggest that mosasaurs led a different lifestyle perhaps as an opportunistic ambush predator.
Illustration of an ichthyosaur is from here.

Serendipity with a backhoe

This is a story of what happens when construction workers have some appreciation for interesting rocks and fossils they come across in the course of their daily tasks:

While excavating oil sands in a mine near the town of Ft. McMurray, Alberta, Canada, a heavy machinery operator uncovered the skeleton of a plesiosaur, the extinct, long-necked reptile that inhabited Mesozoic seas.

The skeleton had been fragmented by its excavation by backhoe rather than small hammers, chisels and brushes, but when pieced back together, it was judged to be 80% complete.

The find is significant because it is the earliest North American occurrence of a plesiosaur, extending the known geologic range of these animals to the early part of the Cretaceous Period and this find also expands the known geographic range of plesiosaurs in North America.

Reference: Journal of Paleontology November, 2009, Earliest North American occurrence of a plesiosaur

Photo credit: http://www.dinosaurjungle.com/focus_plesiosaur.jpg. For more on plesiosaurs, go to this site or click on today's title.