Earth:Ferris Formation

Ferris Formation
Stratigraphic range: Maastrichtian-Danian
~67–63 Ma^[1]

PreЄ

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Ferris Formation; Stratigraphic range: Maastrichtian-Danian; ~67–63 Ma PreЄ Є O S D C P T J K Pg N ↓
Type	Geological formation
Underlies	Hanna Formation
Overlies	Medicine Bow Formation
Thickness	600–2,000 m (2,000–6,600 ft)
Lithology
Primary	Mudstone
Other	Sandstone
Location
Coordinates	[ ⚑ ] : 41°48′N 106°36′W / 41.8°N 106.6°W
Paleocoordinates	[ ⚑ ] 48°48′N 82°12′W / 48.8°N 82.2°W
Region	Wyoming
Country	United States
Extent	Hanna Basin
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The Ferris Formation is an Upper Cretaceous (~67-66 Ma) to Paleocene (66-63 Ma), fluvial-deltaic geological formation in southern Wyoming. It contains a variety of trace and body fossils, preserved in sandy fluvial channel deposits and overbank units. Diverse vertebrate fossils have been reported from the formation.^[1]

The Ferris Formation is up to 2,000 metres (6,600 ft) thick in the Hanna Basin and represents a rapid accumulation of predominantly fine-grained sediment on a broad deltaic and fluvial environments. Some of the fluvial channels contain evidence of tidal influence and brackish water, in the form of tidal facies, shark teeth, and crustacean burrows, which demonstrates that the western shoreline of the Western Interior Sea was close in proximity to the Hanna Basin even during the latest Cretaceous.^[2] The local K-T boundary is contained within a sandy channel deposit made up of stacked bars. Reworked Cretaceous fossils are preserved at the base of the channel complex, associated with mud rip-up clasts, and Paleocene mammal fossils are preserved in the upper portion of the bar.^[3]

Fossils

Color key

Taxon	Reclassified taxon	Taxon falsely reported as present	Dubious taxon or junior synonym	Ichnotaxon	Ootaxon	Morphotaxon

Notes
Uncertain or tentative taxa are in small text; ~~crossed out~~ taxa are discredited.

Diverse vertebrate fossils have been reported from the Ferris Formation, spanning to from Lancian (Cretaceous) to Puercan (Paleocene).^[3] Systematics of mammalian fossil records are based on Lillegraven & Eberle (1999),^[3] while non-mammalian vertebrate fossil records are based on Wroblewski (2026).^[1]

Chondrichthyians

Chondrichthyians of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Dasyatis	D. sp.		Puercan
Lonchidion	L. selachos		Lancian
Myledaphus	M. pustulatus M. sp.
Orectolobiformes	Indeterminate
Restesia	R. monocuspilatus R. americana

Actinopterygians

Actinopterygians of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Amiidae	Indeterminate		Lancian to Puercan
Lepisosteidae	Indeterminate		Lancian to Puercan
Phyllodus	P. paulkatoi		Lancian
Platacodon	P. sp.		Lancian
Teleostei	Indeterminate		Lancian to Puercan

Amphibians

Amphibians of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Caudata	Indeterminate		Lancian
Habrosaurus	H. dilatus		Lancian

Squamates

Lizards of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
cf. Odaxosaurus	cf. O. piger		Lancian
Squamata	Indeterminate		Lancian to Puercan

Testudines

Turtles of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Adocus	A. sp.		Lancian
Baenidae	Indeterminate		Lancian to Puercan
Basilemys	B. sp.		Lancian
Chelonia	Indeterminate
Compsemys	C. victus
Trionychidae	Indeterminate		Lancian to Puercan

Choristoderans

Choristoderans of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Champsosaurus	C. sp.		Lancian to Puercan

Crocodylomorphs

Crocodylomorphs of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Alligatoroidea	Indeterminate		Lancian to Puercan
cf. Borealosuchus	cf. B. sp.		Lancian
Navajosuchus	N. mooki		Puercan

Dinosaurs

Ornithischians

Ornithischians of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Ankylosauridae	Indeterminate		Lancian		Some specimens originally assigned to Ankylosaurus and Edmontonia.^[4]
Chasmosaurinae	Indeterminate				Originally assigned to Triceratops.^[4]
Edmontosaurus	E. annectens
Nodosauridae	Indeterminate				Some specimens originally assigned to Ankylosaurus and Edmontonia.^[4]
Ornithischia	Indeterminate
Stygimoloch	S. spinifer				Some specimens originally identified as thescelosaurids.
Thescelosaurus	T. sp.

Saurischians

Saurischians of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Acheroraptor	A. temertyorum		Lancian		Some specimens originally assigned to Paronychodon and Saurornitholestes.
Dakotaraptor	D. steini				Some specimens originally assigned to Aublysodon, Dromaeosaurus and Saurornitholestes.
Deinonychosauria	Indeterminate
Nanotyrannus	N. lancensis				Specimens originally assigned to Aublysodon.^[3]
Paronychodon	P. lacustris
Pectinodon	P. bakkeri				Some specimens originally assigned to Troodon.
Richardoestesia	R. isosceles				Some specimens originally assigned to Saurornitholestes.
Struthiomimus	S. sedens				Some specimens originally assigned to Ornithomimus.^[4]
Theropoda	Indeterminate
Tyrannosauridae	Indeterminate
Tyrannosaurus	T. rex

Mammals

Eutherians

Eutherians of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Alticonus	A. gazini		Puercan
Alveugena	A. carbonensis
Ampliconus	A. antoni A. sp., cf. A. browni
Arctocyonidae	Indeterminate
Baioconodon	B. sp., cf. B. denverensis B. middletoni B. sp.
Carsioptychus	C. coarctatus				Species originally assigned to Periptychus.
Cimolestes	C. sp. cf. C. sp.		Lancian to Puercan
Conacodon	C. sp., cf. C. cophater C. delphae C. harbourae		Puercan
"Condylartha"	Indeterminate
Ectoconus	E. cavigellii E. ditrigonus E. sp.
Eoconodon	E. sp.
Gypsonictops	G. sp., cf. illuminatus		Lancian
Loxolophus	L. faulkneri L. sp., cf. faulkneri L. sp., cf. hyattianus L. priscus cf. L. sp.		Puercan
Maiorana	M. ferrisensis
Mimatuta	M. sp. cf. M. sp.
Mithrandir	M. gillianus M. sp., cf. gillianus
Oxyacodon	O. sp., cf. O. agapetillus O. apiculatus O. priscilla
Oxyclaenus	O. cuspidatus cf. O. sp.
Oxyprimus	O. galadrielae O. sp.
Palaeoryctidae	Indeterminate
Periptychidae	Indeterminate
Procerberus	P. sp.
"Proteutheria"	Indeterminate
cf. Protoselene	cf. P. sp.
Protungulatum	P. donnae P. sp., cf. donnae P. gorgun P. sloani
Valenia	V. wilsoni				Species originally assigned to Promioclaenus.

Metatherians

Metatherians of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Peradectes	P. sp., cf. P. pusillus		Puercan
Peradectidae	Indeterminate		Lancian
Protalphadon	P. lulli P. sp. cf. lulli		Lancian		Species originally assigned to Alphadon.

Multituberculates

Multituberculates of the Ferris Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Cimolodon	C. nitidus C. sp., cf. nitidus		Lancian
Ectypodus	E. sp. A E. sp. B		Puercan
Meniscoessus	M. seminoensis		Lancian
Mesodma	M. ambigua M. formosa M. hensleighi M. sp., cf. M. garfieldensis M. sp. ?M. sp.		Puercan
Neoplagiaulacidae	Indeterminate		Lancian to Puercan
Ptilodus	P. sp., cf. P. tsoiensis P. sp.		Puercan
Taeniolabis	T. taoensis
Valenopsalis	V. joyneri				Species originally assigned to Catopsalis.

References

↑ ^1.0 ^1.1 ^1.2 Wroblewski, A. F. (2026). "Systematics and biostratigraphy of non-mammalian vertebrates across the K/Pg transition, southern Wyoming, USA". Journal of Paleontology 100 (1): 222–250. doi:10.1017/jpa.2025.10191. Supplemental Information
↑ Wroblewski, A. F. (2008). "Paleoenvironmental Significance of Cretaceous and Paleocene Psilonichnus in Southern Wyoming". Palaios 23 (6): 370–379. doi:10.2110/palo.2007.p07-005r.
↑ ^3.0 ^3.1 ^3.2 ^3.3 Lillegraven, Jason A.; Eberle, Jaelyn J. (1999). "Vertebrate Faunal Changes through Lancian and Puercan Time in Southern Wyoming". Journal of Paleontology 73 (4): 691–710. doi:10.1017/S0022336000032510. Bibcode: 1999JPal...73..691L. https://www.jstor.org/stable/1306768. Retrieved 2020-11-16.
↑ ^4.0 ^4.1 ^4.2 ^4.3 Weishampel, Dodson & Osmólska 2004.

Bibliography

Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004), The Dinosauria, 2nd edition, Berkeley: University of California Press, pp. 1–880, ISBN 0-520-24209-2, https://books.google.com/books?id=vtZFDb_iw40C, retrieved 2019-02-21

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Original source: https://en.wikipedia.org/wiki/Ferris Formation. Read more

[W26-1] 1.0 ^1.1 ^1.2 Wroblewski, A. F. (2026). "Systematics and biostratigraphy of non-mammalian vertebrates across the K/Pg transition, southern Wyoming, USA". Journal of Paleontology 100 (1): 222–250. doi:10.1017/jpa.2025.10191. Supplemental Information

[W08-2] Wroblewski, A. F. (2008). "Paleoenvironmental Significance of Cretaceous and Paleocene Psilonichnus in Southern Wyoming". Palaios 23 (6): 370–379. doi:10.2110/palo.2007.p07-005r.

[LE99-3] 3.0 ^3.1 ^3.2 ^3.3 Lillegraven, Jason A.; Eberle, Jaelyn J. (1999). "Vertebrate Faunal Changes through Lancian and Puercan Time in Southern Wyoming". Journal of Paleontology 73 (4): 691–710. doi:10.1017/S0022336000032510. Bibcode: 1999JPal...73..691L. https://www.jstor.org/stable/1306768. Retrieved 2020-11-16.

[FOOTNOTEWeishampelDodsonOsmólska2004-4] 4.0 ^4.1 ^4.2 ^4.3 Weishampel, Dodson & Osmólska 2004.

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