STINGRAYS DO IT IN THE MUD AT FOSSIL LAKE, WYOMING
Photos by Lance Grande from The Lost World of Fossil Lake: Snapshots from Deep Time, published on June 14, 2013 by the University of Chicago Press [ Amazon ]
The creatures in these photos [retrieved from Live Science] were all entombed at the bottom of Wyoming's long-gone Fossil Lake, which was teeming with life during the early Eocene, about 52 million years ago.
Mini-Horse. This is the most complete skeleton of a so-called dawn horse ever discovered. This specimen of Protorohippus venticolus was much more diminutive than today's horses, standing less than two feet high at the shoulder, but its long back legs suggest it was a good jumper. Perhaps it was less skilled as a swimmer; researchers aren't sure how the horse ended up at the bottom of the middle of Fossil Lake but they suspect it drowned, possibly trying to escape a predator.
These two adult fossilized turtles, each more than 4 feet long, belong to the species Christernon undatum. They flourished during the Late Cretaceous but became extinct in the late Eocene, meaning the specimens shown here represent some of the last survivors of their kind.
Only one frog has ever been found at the formation. The single specimen pictured here measures just 1.6 inches (4 cm) long.
The pièce de résistance: male and female fat-tailed stingrays (Asterotrygon maloneyi) shown here were likely mating or just about to mate when they were killed, researchers believe.