Lance Formation
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The Lance Formation is a division of Late Cretaceous rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils represent important components of the latest Mesozoic vertebrate faunas.
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[edit] Occurrence
The Lance Formation occurs in the uppermost rock unit of the Cretaceous.
[edit] Importance
At least tens of thousands of Late Cretaceous vertebrate remains have been recovered from the Lance Formation. Fossils ranging from microscopic elements to extensive bonebeds, with nearly complete, sometimes articulated dinosaur skeletons, have been found.
[edit] Size
The formation varies in thickness from about 90m (300 feet) in North Dakota, to almost 600m (2,000 feet) in parts of Wyoming.
[edit] Paleontology
The Lance Formation was laid down by streams, on a coastal plain along the edge of the Western Interior Seaway. Most of the animals known from the formation are freshwater animals, and some are exclusively freshwater forms (for instance, frogs and salamanders). However, marine fossils are also found in the formation, suggesting that the sea was nearby.
Animal fossils that have been found in the Lance Formation include: fishes, frogs, salamanders, champsosaurs, turtles, lizards, snakes, crocodiles, pterosaurs, mammals, birds, and dinosaurs. Some well known dinosaurs found in the formation include: Triceratops, Torosaurus, Tyrannosaurus, Edmontosaurus, Pachycephalosaurus, Ankylosaurus, Edmontonia, Thescelosaurus, Troodon, Dromaeosaurus, Ricardoestesia, and Ornithomimus.
[edit] Trivia
- Tyrannosaurus rex was discovered in the Lance Formation
[edit] See Also
- List of fossil sites (with link directory)
