The Willow Tank Formation is a geologic formation which outcrops in the U.S. state of Nevada. Initially believed to be of Early Cretaceous (Albian) age, later studies have concluded that it was more likely to be of Late Cretaceous (Cenomanian) age, making it equivalent to the Wayan Formation and the Mussentuchit Member of the Cedar Mountain Formation. It was deposited in an anastomosed fluvial system.
Fossil records The list is primarily based on Bonde (2008) and Bonde et al. (2008), unless stated otherwise.
Plants Plants of the Willow Tank Formation Genus Species Presence Materials Notes Images Cladophlebis C. sp. Matonia M. sp.
Gastropods Gastropods of the Willow Tank Formation Genus Species Presence Materials Notes Images Gastropoda indeterminate Single shell
Fish Fishes of the Willow Tank Formation Genus Species Presence Materials Notes Images Ceratodus C. sp. Teeth plates Lepisosteidae indeterminate Ganoid scales, rectangular to rhoombohedral in shape Holostean indeterminate Ganoid scales, polygonal in shape
Testudines Turtles of the Willow Tank Formation Genus Species Presence Materials Notes Images Naomichelys N. speciosa Carapace and plastron elements Baenidae indeterminate Shell elements and a pelvic girdle cf. Adocus cf. A. sp. Several shell specimens ?Trionychidae indeterminate Fragmentary specimens
Crocodylomorphs Crocodylomorphs of the Willow Tank Formation Genus Species Presence Materials Notes Images Crocodylomorpha indeterminate Dental elements and scutes
Dinosaurs Dinosaurs of the Willow Tank Formation Genus Species Presence Materials Notes Images Theropoda indeterminate Dental elements, and two different eggshell morphotypes One of the eggshell morphotype shows similarities with Macroelongatoolithus carylei Tyrannosauroidea indeterminate Dental elements Dromaeosauridae indeterminate Femur, tibia and teeth Titanosauriformes indeterminate Single tooth Nevadadromeus N. schmitti Partial skeleton Iguanodontia indeterminate Teeth and partial skeletonIncludes Iguanodon-grade taxa and hadrosaur-grade taxa according to Bonde (2008). Thyreophora indeterminate Dental remains
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