Kaiparowits Formation

The Kaiparowits Formation is a sedimentary rock formation found in the Kaiparowits Plateau in Grand Staircase-Escalante National Monument, in the southern part of Utah in the western United States. It is over 2800 feet thick, and is Campanian in age. This Upper Cretaceous formation was formed from alluvial floodplains of large rivers in coastal southern Laramidia; sandstone beds are the deposit of rivers, and mudstone beds represent floodplain deposits. It is fossiliferous, with most specimens from the lower half of the formation, but exploration is only comparatively recent, with most work being done since 1982. It has been estimated that less than 10% of the Kaiparowits formation has been explored for fossils. Most fieldwork has been conducted by The Natural History Museum of Utah.

Traditionally, the Kaiparowits Formation has been considered to be roughly equivalent in age to the northern Dinosaur Park Formation. This, combined with the differences in fauna between the two formations, has led some scientists, most notably Scott Sampson, to conclude that there was some kind of barrier separating northern and southern Laramidia at this time. However, preliminary re-calibration of late Cretaceous formation correlations suggests that the upper part of the Kaiparowits, where many of the unique species are found, is actually younger than the Dinosaur Park, and that some Kaiparowits species may in fact simply be descendants of Dinosaur Park species.

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