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
outcrop
An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth and other terrestrial planets.
Features
Outcrops do not cover the majority of the Earth's land surface because in most p ...
s in the U.S. state of
Nevada
Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
. Initially believed to be of
Early Cretaceous
The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...
(
Albian
The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...
) age,
later studies have concluded that it was more likely to be of
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...
(
Cenomanian
The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...
) age,
making it equivalent to the
Cloverly and
Cedar Mountain Formation
The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid-Cretaceous. The formation was named for Cedar Mountain (Utah), Cedar Mountain in northern Emery Cou ...
s. 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.
The abbreviation cf. (short for either Latin or , both meaning 'compare') is generally used in writing to refer the reader to other material to make a comparison with the topic being discussed. However some sources offer differing or even contr ...
Adocus
''Adocus'' is an extinct genus of aquatic turtles belonging to the family Adocidae.
Description
Species of the genus ''Adocus'' had flattened and smoothly contoured shells with horny sculptured plates. The shells could reach a length of at le ...
''
* ''
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 , 'horn' and 'tooth') is an extinct genus of freshwater lungfish that was found worldwide during the Mesozoic Era. It has been described as a "catch all", and a " form genus" used to refer to the remains (typically tooth ...
'' sp.
*
Coprolites
A coprolite (also known as a coprolith) is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. The name i ...
(indet.)
*
Crocodyliformes
Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseu ...
indet.
*
Gastropoda
Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, freshwater, and fro ...
indet.
*
Holostei
Holostei is a group of ray-finned bony fish. It is divided into two major clades, the Halecomorphi, represented by the single living genus, '' Amia'' with two species, the bowfins (''Amia calva'' and '' Amia ocellicauda''), as well as the Gin ...
indet.
*
Lepisosteidae
Gars are an ancient group of ray-finned fish in the Family (biology), family Lepisosteidae. They comprise seven living species of fish in two genera that inhabit Fresh water, fresh, Brackish water, brackish, and occasionally marine waters of eas ...
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 strata in North America. It appears to be the preserved remains of arthropod feeding burrows.
References
See also
* Ichnology
A trace fossil, also called an ichnofossil (; ), is a ...
sp.
*
Trionychidae
Trionychidae is a family of turtles, commonly known as softshell turtles or simply softshells. The family was described by Leopold Fitzinger in 1826. Softshells include some of the world's largest freshwater turtles, though many can adapt to li ...
(?) indet.
Dinosaurs
*
Dromaeosauridae
Dromaeosauridae () is a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from ...
indet.
*
Iguanodontia
Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (). They represent one of the most successful groups of herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and relatively sm ...
indet.
* ''
Macroelongatoolithus carlylei''
* ''
Nevadadromeus schmitti''
*
Ornithopoda
Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (). They represent one of the most successful groups of herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and relatively sm ...
indet.
*
indet.
*
Titanosauriformes
Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...
indet.
*
Thyreophora
Thyreophora ("shield bearers", often known simply as "armored dinosaurs") is a group of armored ornithischian dinosaurs that lived from the Early Jurassic until the end of the Cretaceous.
Thyreophorans are characterized by the presence of bod ...
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 ...
indet.
References
Geologic formations of Nevada
Claystone formations
Conglomerate formations of the United States
Sandstone formations of the United States
{{Geologic-formation-stub