The Sundance Sea was an Epeiric Sea that existed in North America during the mid-to-late Jurassic Period of the Mesozoic Era.[ ] It was an arm of what is now the Arctic Ocean, and extended through what is now western Canada into the central western United States. The sea receded when highlands to the west began to rise.
Stratigraphy
The Sundance Sea did not occur at a single time; geological evidence suggests that the Sea was actually a series of five successive marine transgressions—each separated by an
unconformity—which advanced and receded from the middle
Jurassic onward.
The terrestrial sediments of the Morrison Formation—eroded from rising highlands to the west—were deposited on top of the marine Sundance sediments as the sea regressed for the last time late in the Jurassic.
Fauna
The Sundance Sea was rich in many types of animals.
Gryphaea was extremely common, and
shark teeth have been found. In addition to
fish,
and to an extent
have been found in sediments from the Sundance Sea.
and
bivalvia would have dotted the seafloor.
Ophthalmosaurus, a large long
Ichthyosauria, swam in the seas using its large, long jaws to catch belemnite 'squid'.
, a 15–20 foot (4.5–6 m) long
Cryptoclididae plesiosaur, went after the easier-to-catch fish.
The largest
marine reptile in the Sundance Sea was
Megalneusaurus, a long
pliosaur similar to
Liopleurodon.
[Knight WC. 1895 A new Jurassic plesiosaur from Wyoming. Science 2: 449.] Its fossils have been found in Alaska and Wyoming, which were both covered by the Sundance Sea when it was alive.
During the periods of recession, and other Jurassic terrestrial animals frequented the shores, as evidenced by the Red Gulch Dinosaur Tracksite near Shell, Wyoming.
See also
External links
