The Willow Tank Formation is a
geologic formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
which
outcrops in the U.S. state of
Nevada
Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
. Initially believed to be of
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pro ...
(
Albian) age,
later studies have concluded that it was more likely to be of
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
(
Cenomanian
The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...
) age,
making it equivalent to the
Cloverly and
Cedar Mountain Formations. It was deposited in an anastomosed fluvial system.
Paleofauna
All paleofauna listed are taken from a list compiled by Bonde (2008a)
unless stated otherwise.
Non-dinosaurs
* ''
cf. Adocus
''Adocus'' is an extinct genus of aquatic turtles belonging to the family Adocidae. ''Adocus'' was once considered to belong to the family Dermatemyidae.
Description
Species of the genus ''Adocus'' had flattened and smoothly contoured shells w ...
''
* ''
Baena
Baena is a town and municipalities in Spain, municipality of Spain located in the Córdoba Province, Spain, province of Córdoba, Andalusia. It is situated near the on the slope of a hill southeast of Córdoba, Spain, Córdoba by road. The popu ...
'' sp.
* ''
Ceratodus
''Ceratodus'' (from el, κέρας , 'horn' and el, ὀδούς 'tooth') was a wide-ranging genus of extinct lungfish. Fossil evidence dates back to the Early Triassic. A wide range of fossil species from different time periods have been found ...
'' sp.
*
Coprolites (indet.)
*
Crocodyliformes indet.
*
Gastropoda
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. ...
indet.
*
Holostei indet.
*
Lepisosteidae indet.
* ''
Naomichelys
''Naomichelys'' is an extinct genus of helochelydrid stem turtle known from the Cretaceous (Aptian-Campanian) of North America. It is the only member of the family known to be native to North America.
Distribution
''Naomichelys'' is known nume ...
'' sp.
* ''
Scoyenia
''Scoyenia'' is an ichnogenus found in paleozoic-mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lastin ...
sp.
*
Trionychidae (?) indet.
Dinosaurs
*
Dromaeosauridae indet.
*
Iguanodontia indet.
* ''
Macroelongatoolithus carlylei''
* ''
Nevadadromeus schmitti''
*
Ornithopoda indet.
*
Theropoda
Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally ca ...
indet.
*
Titanosauriformes indet.
*
Thyreophora indet.
*
Tyrannosauroidea
Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent b ...
indet.
References
Geologic formations of Nevada
{{Geologic-formation-stub