Straight Cliffs Formation
Group Genus Species Stratigraphic Position Source
Chondrichthyes Scapanorhynchus S. raphiodon ( Agassiz ) Tibbet Canyon Member Peterson , 1969
Chondrichthyes Lamna L. appendiculata Agassiz John Henry Member Peterson , 1969
Chondrichthyes Chiloscyllium C. grenni Tibbet Canyon Member Eaton et al . , 1999
Chondrichthyes Squalicorax S. falcatus Tibbet Canyon Member Eaton et al . , 1999
Chondrichthyes Cretodus C. semiplicatus Tibbet Canyon Member Eaton et al . , 1999 ( wrongly attributed to Ceratodus semiplicatus )
Chondrichthyes Phychodus sp John Henry Member Peterson , 1969
Chondrichthyes Lissodus sp John Henry Member Eaton et al . , 1999
Chondrichthyes Hybodus sp John Henry Member Eaton et al . , 1999
Chondrichthyes Ptychodus P. mortoni Agassiz , 1843 John Henry Member Eaton et al . , 1999
Chondrichthyes Undifferentiated John Henry Member Peterson , 1969
Osteichthyes Lepisosteus sp John Henry Member Eaton et al . , 1999
Osteichthyes Atractosteus sp John Henry Member Eaton et al . , 1999
Urodela Albanerpeton sp John Henry Member Eaton et al . , 1999
Testudines Adocus sp John Henry Member Eaton et al . , 1999
Testudines Aspideretes sp John Henry Member Eaton et al . , 1999
Testudines Basilemys sp John Henry Member Eaton et al . , 1999
Testudines Naomichelys sp John Henry Member Eaton et al . , 1999
Squamata Odaxosaurus O. piger ( Gilmore , 1928 ) John Henry Member Eaton et al . , 1999
Crocodylia Bernissartia sp John Henry Member Eaton et al . , 1999
Crocodylia Mesoeucrocodylia Irmis et al . , 2013
Paleontology -- Vertebrate fossils
Vertebrate fossils have been found throughout the Straight Cliffs Formation . The fossils from the Straight Cliffs Formation document a diverse assemblage of therian mammals . [ 21 ] [ 22 ] The Tibbet Canyon Member contains sharks ’ teeth from marine deposits rare mammal fossils from deltaic deposits . [ 22 ] Recovered fossils include sharks , rays , lepisosteid fishes , crocodyliforms , and fragmentary marsupial mammal teeth . [ 22 ] The Smoky Hollow Member also contains a variety of sharks , amphibians , reptiles , snakes , crocodyliforms , and dinosaurs . The member also contains multituberculate and marsupial mammals . The John Henry Member contains more brackish and marine fauna , as well as mammals and other terrestrial species which are less common . [ 22 ] The Drip Tank Member is primarily fluvial and consequently only water worn fragments of turtle and crocodyliforms have been recovered . [ 22 ]
The Straight Cliffs Formation is a stratigraphic unit in the Kaiparowits Plateau of south central Utah. It is Late Cretaceous (latest Turonian - early Campanian) in age and contains fluvial (river systems), paralic (swamps and lagoons), and marginal marine (shoreline) siliciclastic strata. It is well exposed around the margin of the Kaiparowits Plateau in the Grand Staircase - Escalante National Monument in south central Utah. The formation is named after the Straight Cliffs, a long band of cliffs creating the topographic feature Fiftymile Mountain. The Straight Cliffs Formation was deposited in a marginal marine basin system along the western edge of the Cretaceous Western Interior Seaway. It is bounded below by the Tropic Shale and above by the Wahweap Formation. A variety of fossil species have been found within the Straight Cliffs including ammonites, mollusks, foraminifera, ostracods, sharks, fish, amphibians, turtles, lizards, crocodyliforms, dinosaurs, and mammals.