imported>Volcanoguy: removed Category:Siltstone formations; added Category:Siltstone formations of the United States using HotCat

2025-06-04T23:01:03Z

removed Category:Siltstone formations; added Category:Siltstone formations of the United States using HotCat

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{{Use American English|date=November 2020}}
{{Short description|A geologic formation in New Mexico}}
{{Infobox rockunit
| name = Nacimiento Formation
| image = Angel Peak.jpg
| caption = The [[badlands]] below [[Angel Peak Scenic Area|Angel Peak]] are made up of Nacimiento Formation rocks
| type = [[Formation (stratigraphy)|Formation]]
| age = [[Paleocene]]<br> ~{{fossilrange|65.7|61}}
| period = Paleocene
| prilithology = [[Shale]]
| otherlithology = [[Siltstone]], [[sandstone]]
| namedfor = Nacimiento (now [[Cuba, New Mexico]])
| namedby = J.H. Gardner
| year_ts = 1910
| region = [[New Mexico]]
| country = [[United States]]
| coordinates = {{coord|36.0126977|N|106.9855481|W|display=inline}}
| unitof =
| subunits =
| underlies = [[San Jose Formation]]
| overlies = [[Ojo Alamo Formation]]
| thickness = {{convert|254|m|feet|abbr=on}}
| extent =
| area =
| map = {{Location map+ | United States#New Mexico
| relief = 1
| width = 250
| float = center
| places =
{{Location map~ | United States#New Mexico
| lat_deg = 36.013
| lon_deg = -106.986
| mark = Orange pog.svg
| marksize = 12
}}
}}
| map_caption =
}}

The '''Nacimiento Formation''' is a [[sedimentary]] [[geological formation|rock formation]] found in the [[San Juan Basin]] of western [[New Mexico]] ([[United States]]).{{sfn|Williamson|Lucas|1992}} It has an age of 61 to 65.7 million years, corresponding to the early and middle [[Paleocene]]. The formation has yielded an abundance of fossils from shortly after the [[Cretaceous-Paleogene extinction event]] that provide clues to the recovery and diversification of [[mammals]] following the extinction event.

== Description ==
The Nacimiento Formation is a heterogeneous nonmarine formation composed of [[shale]], [[siltstone]], and [[sandstone]],{{sfn|Schoch|1981}} deposited in [[floodplain]], [[river|fluvial]] and [[lake|lacustrine]] settings,{{sfn|Lucas|Ingersoll|1981}} and made up of [[sediment]] shed from the San Juan uplift to the north and the Brazos-Sangre de Cristo uplift to the east.{{sfn|Lucas|1984}} It was deposited mostly between ~65.7 and ~61 million years ago, during the early and middle Paleocene.{{sfn|Williamson|1996}} The climate was humid and warm to hot{{sfn|Tidwell|Ash|Parker|1981}} and stable, but with a distinct dry season.{{sfn|Davis|Peppe|Atchley|Williamson|2016}} This unit interbeds with the underlying [[Ojo Alamo Formation]] but is separated by an [[unconformity]] from the overlying [[San Jose Formation]].{{sfn|Lucas|Ingersoll|1981}}

The Nacimiento Formation is divided into several subunits known as [[Geological unit|members]]. In outcrops in southern areas of the formation, the [[Puercan]] fauna is found in the Arroyo Chijuillita Member, the [[Torrejonian]] fauna is found in the Ojo Encino Member, and the uppermost Escavada Member lacks age-diagnostic [[fossils]].{{sfn|Williamson|Lucas|1992}} In northern outcrops, the two lower members are indistinguishable, and are called the "main body".{{sfn|Williamson|1996}} Above them are two more informal members. These preserve a younger, [[Tiffanian]] fauna.{{sfn|Libed|2005}} The Puercan and Torrejonian faunas are further subdivided into several [[Biostratigraphy|biostratigraphic zones]].{{sfn|Williamson|1996}}

== Fossils ==
Many fossils are known from the Nacimiento Formation, although bone is often altered into [[phosphate|phosphatic]] [[concretion]]s.{{sfn|Simpson|1959}} Fossils belonging to a number of different organisms have been found here, including: plants (mostly [[dicotyledon]]ous [[angiosperm]]s),{{sfn|Tidwell|Ash|Parker|1981}}{{sfn|Anderson|1960}} [[gastropod]]s, [[freshwater]] [[bivalve]]s,{{sfn|Hartman|1981}} [[chondrichthyes|cartilaginous fish]] and [[osteichthyes|bony fish]], salamanders, turtles, [[choristodera|champsosaurs]], [[amphisbaenia]]ns, lizards, snakes, crocodilians,{{sfn|Sullivan|Lucas|1986}} birds,{{sfn|Gardner|1910}} and a variety of archaic mammals. Mammalian groups represented include [[multituberculate]]s,{{sfn|Williamson|Brusatte|Secord|Shelley|2016 }} [[plesiadapiform]]s,{{sfn|Silcox|Williamson |2012}} [[didelphid]] [[marsupial]]s, [[insectivora]]ns, [[carnivora]]ns, [[taeniodont]]s, [[Mesonychia|mesonychians]], [[condylarth]]s, and [[cimolesta]]ns.{{sfn|Williamson|Lucas|1992}} Fossil remains found in the formation support the validity of the genus ''[[Thylacodon]]'' and the species ''T. montanensis''.{{sfn|Williamson|Brusatte|Carr|Weil|2012}}

These fossils provide important clues to the impact of the [[Cretaceous–Paleogene extinction event]] on [[mammals]]{{sfn|Williamson|Brusatte|Carr|Weil|2012}} and to the recovery, evolution, and turnover of mammals shortly after the event. The formation and its fossils provide a particularly clear record of the To2-To3 turnover event, allowing the timing of the event to be constrained to between 62.59 and 62.47 million years ago. The event may have been associated with climate change or with the rapid development of a river system across the San Juan basin, which caused a temporary pause in sediment deposition that separates the Nacimiento Formation from the San Jose Formation.{{sfn|Leslie|Peppe|Williamson|Bilardello|2018}}

== Fossil content ==

{{paleobiota-key-compact}}

=== Birds ===
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Bird|Birds]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

=== Mammals ===

==== Carnivorans ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Carnivora|Carnivorans]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Cimolestans ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Cimolesta|Cimolestans]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Condylarths ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Condylarthra|Condylarths]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Insectivorans ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Insectivora|Insectivorans]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Marsupials ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Marsupial|Marsupials]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Mesonychians ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Mesonychia|Mesonychians]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Multituberculates ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Multituberculata|Multituberculates]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Pantodonts ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Pantodonta|Pantodonts]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Plesiadapiforms ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Plesiadapiformes|Plesiadapiforms]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

=== Crocodyliformes ===
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Crocodyliformes]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

=== Reptiles ===
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Reptile|Reptiles]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

=== Squamates ===
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Squamata|Squamates]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

=== Turtles ===
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Turtle|Turtles]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

=== Amphibians ===
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Amphibia|Amphibians]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

=== Fish ===

==== Boney Fish ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Osteichthyes|Boney Fish]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Cartilaginous Fish ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Chondrichthyes|Cartilaginous Fish]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

=== Molluscs ===

==== Bivalves ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Bivalvia|Bivalves]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

==== Gastropods ====
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | [[Gastropoda|Gastopods]] of the Nacimiento Formation
|-
! Genus
! Species
! Location
! Stratigraphic position
! Material
! Notes
! Images
|}

== History of investigation ==
[[Edward Drinker Cope]] described the fossils during the [[Wheeler Survey]].<ref>{{cite web |last1=Wheeler |first1=George |last2=[[Charles Abiathar White|White]] |first2=Charles |last3=Cope |first3=Edward |title=Report upon United States geological surveys west of the one hundredth meridian, Volume IV: Paleontology |url=https://pubs.er.usgs.gov/publication/70039253 |website=USGS |publisher=US Government Printing Office |access-date=16 February 2023 |date=1877}}</ref>

Workers in the early 1900s divided the rocks of the Nacimiento Formation into two formations, the lower Puerco Formation and the upper Torrejon Formation.{{sfn|Gardner|1910}} This was rejected on the grounds that there were no [[lithology|lithological]] differences between the two, only differences in [[fossil]] faunas, making determination of which formation was present in a given area impossible if fossils could not be found.{{sfn|Simpson|1959}} The Puerco and Torrejon were retained as zones within the Nacimiento Formation, and their faunas became the basis of the [[Puercan]] and [[Torrejonian]] [[North American Land Mammal Ages]].{{sfn|Fassett|1992}}

== Footnotes ==
{{Reflist}}

== References ==
* {{Cite book|last=Anderson |first=R.Y. |year=1960 |title=Cretaceous-Tertiary palynology, eastern side of the San Juan Basin, New Mexico |series=Memoir '''6''' |publisher=New Mexico Bureau of Mines and Mineral Resources |location=Socorro, New Mexico |url=https://geoinfo.nmt.edu/publications/monographs/memoirs/downloads/6/Memoir-6.pdf |access-date=8 June 2020}}
* {{cite journal |last1=Davis |first1=Adam J. |last2=Peppe |first2=Daniel J. |last3=Atchley |first3=Stacy C. |last4=Williamson |first4=Thomas E. |last5=Flynn |first5=Andrew G. |title=Climate and landscape reconstruction of the Arroyo Chijuillita Member of the Nacimiento Formation, San Juan Basin, New Mexico: Providing environmental context to early Paleocene mammal evolution |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=December 2016 |volume=463 |pages=27–44 |doi=10.1016/j.palaeo.2016.09.011|bibcode=2016PPP...463...27D |doi-access=free }}
* {{Cite book|last=Fassett |first=J.E. |title=Ghost Ranch |editor=Siemers, C.T. |editor2=Woodward, L.A. |editor3=Callender, J.F. |publisher=New Mexico Geological Society|location=Socorro, New Mexico|date=1992|series=New Mexico Geological Society Guidebook |volume=25 |pages=225–230 |chapter=Cretaceous and Tertiary rocks of the eastern San Juan Basin, New Mexico and Colorado |citeseerx=10.1.1.527.6438 }}
* {{cite journal |doi=10.1086/621799 |last=Gardner |first=J.H. |year=1910 |title=The Puerco and Torrejon formations of the Nacimiento Group |journal=Journal of Geology |volume=18 |issue=8 |pages=702–741|bibcode = 1910JG.....18..702G |doi-access= }}
* {{cite journal |doi=10.1130/0016-7606(1981)92<942:ETNMON>2.0.CO;2 |last=Hartman |first=J.H. |year=1981 |title=Early Tertiary nonmarine Mollusca of New Mexico: a review |journal=Geological Society of America Bulletin |volume=92 |issue=12 |pages=I 942–I 950|bibcode = 1981GSAB...92..942H }}
* {{cite journal |last1=Leslie |first1=Caitlin |last2=Peppe |first2=Daniel |last3=Williamson |first3=Thomas |last4=Bilardello |first4=Dario |last5=Heizler |first5=Matthew |last6=Secord |first6=Ross |last7=Leggett |first7=Tyler |title=High-resolution magnetostratigraphy of the Upper Nacimiento Formation, San Juan Basin, New Mexico, USA: Implications for basin evolution and mammalian turnover |journal=American Journal of Science |date=March 2018 |volume=318 |issue=3 |pages=300–334 |doi=10.2475/03.2018.02|bibcode=2018AmJS..318..300L |s2cid=135327595 |url=https://osf.io/qxw4n/ |url-access=subscription }}
* {{Cite book|last=Libed |first=S.A. |year=2005 |title=Lithostratigraphy and mammalian biostratigraphy of the Torrejonian-Tiffanian transition in the Nacimiento Formation, northwestern San Juan Basin, New Mexico |series=M.A. thesis |publisher=University of New Mexico |location=Albuquerque, New Mexico}}
* {{Cite book|last1=Lucas |first1=S.G. |title=Rio Grande Rift: northern New Mexico |editor=Baldridge, W.S. |editor2=Dickerson, P.W. |editor3=Riecker, R.E. |editor4=Zidek, J. |publisher=New Mexico Geological Society|location=Socorro, New Mexico |date=1984|series=New Mexico Geological Society Guidebook|volume=35 |pages=123–128 |chapter=Correlation of Eocene rocks of the northern Rio Grande Rift and adjacent areas: implications for Laramide tectonics |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/35/35_p0123_p0128.pdf |access-date=8 June 2020}}
* {{cite journal |doi=10.1130/0016-7606(1981)92<917:CCDONM>2.0.CO;2 |last1=Lucas |first1=S.G. |author-link2=Spencer G. Lucas |last2=Ingersoll |first2=R.V. |year=1981 |title=Cenozoic continental deposits of New Mexico: an overview |journal=Geological Society of America Bulletin |volume=92 |issue=12 |pages=I 917–I 932, II 1807–II 1981|bibcode = 1981GSAB...92..917L }}
* {{cite journal |last=Schoch |first=R.M. |year=1981 |title=Taxonomy and biostratigraphy of the early Tertiary Taeniodonta (Mammalia: Eutheria) |journal=Geological Society of America Bulletin |volume=92 |issue=12 |page=I 933-I 941, II 1982-II 2267 |doi=10.1130/gsab-p2-92-1982|bibcode=1981GSAB...92.1982S }}
* {{cite journal |last1=Silcox |first1=Mary T. |last2=Williamson |first2=Thomas E. |title=New discoveries of early Paleocene (Torrejonian) primates from the Nacimiento Formation, San Juan Basin, New Mexico |journal=Journal of Human Evolution |date=December 2012 |volume=63 |issue=6 |pages=805–833 |doi=10.1016/j.jhevol.2012.09.002|pmid=23084622 }}
* {{cite journal |last=Simpson |first=G.G. |year=1959 |title=Fossil mammals from the type area of the Puerco and Nacimiento strata, Paleocene of New Mexico |journal=American Museum Novitates |issue=1957 |url=http://digitallibrary.amnh.org/bitstream/handle/2246/2497/N1957.pdf?sequence=1 |access-date=8 June 2020}}
* {{cite journal |doi=10.2307/1563945 |last1=Sullivan |first1=R.M. |last2=Lucas |first2=S.G. |author-link2=Spencer G. Lucas |year=1986 |title=Annotated list of fossil vertebrates from the Paleocene Nacimiento Formation (Puercan-Torrejonian), San Juan Basin, New Mexico |journal=Journal of Herpetology |volume=20 |issue=2 |pages=202–209 |jstor=1563945}}
* {{Cite book|last1=Tidwell |first1=W.D. |last2=Ash |first2=S.R. |last3= Parker |first3=L.R. |year=1981 |chapter=Cretaceous and Tertiary floras of the San Juan Basin |title=Advances in San Juan Basin paleontology |pages=307–332 |editor=Lucas, S.G. |editor2=Rigby Jr., J.K. |editor3=Kues, B.S. |publisher=University of New Mexico Press |location=Albuquerque, New Mexico |isbn=0-8263-0554-7}}
* {{Cite book|last=Williamson |first=T.E. |year=1996 |title=The beginning of the age of mammals in the San Juan Basin, New Mexico: biostratigraphy and evolution of Paleocene mammals of the Nacimiento Formation |series=New Mexico Museum of Natural History and Science Bulletin, '''8''' |publisher=New Mexico Museum of Natural History and Science |location=Albuquerque, New Mexico |url=https://nmdigital.unm.edu/digital/collection/bulletins/id/1210/ |access-date=8 June 2020}}
* {{cite journal |last1=Williamson |first1=Thomas E. |last2=Brusatte |first2=Stephen L. |last3=Carr |first3=Thomas D. |last4=Weil |first4=Anne |last5=Standhardt |first5=Barbara R. |title=The phylogeny and evolution of Cretaceous–Palaeogene metatherians: cladistic analysis and description of new early Palaeocene specimens from the Nacimiento Formation, New Mexico |journal=Journal of Systematic Palaeontology |date=1 December 2012 |volume=10 |issue=4 |pages=625–651 |doi=10.1080/14772019.2011.631592|s2cid=83996185 }}
* {{cite journal |last1=Williamson |first1=Thomas E. |last2=Brusatte |first2=Stephen L. |last3=Secord |first3=Ross |last4=Shelley |first4=Sarah |title=A new taeniolabidoid multituberculate (Mammalia) from the middle Puercan of the Nacimiento Formation, New Mexico, and a revision of taeniolabidoid systematics and phylogeny: Revision of Taeniolabidoidea |journal=Zoological Journal of the Linnean Society |date=May 2016 |volume=177 |issue=1 |pages=183–208 |doi=10.1111/zoj.12336|doi-access=free }}
* {{Cite book|last1=Williamson |first1=T.E. |last2=Lucas |first2=S.G. |author-link2=Spencer G. Lucas |title=San Juan Basin IV|editor=Lucas, S.G. |editor2=Kues, B.S. |editor3=Williamson, T.E. |editor4=Hunt, A.P. |publisher=New Mexico Geological Society|location=Socorro, New Mexico|date=1992|series=New Mexico Geological Society Guidebook|volume=43|pages=265–296|chapter=Stratigraphy and mammalian biostratigraphy of the Paleocene Nacimiento Formation, southern San Juan basin, New Mexico|isbn=99922-2-673-0 |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/43/43_p0265_p0296.pdf |access-date=26 August 2020}}

{{Chronostratigraphy of Colorado|Cenozoic state=expanded}}

[[Category:Paleogene formations of New Mexico]]
[[Category:Natural history of New Mexico]]
[[Category:Paleocene Series of North America]]
[[Category:Paleontology in New Mexico]]
[[Category:Shale formations of the United States]]
[[Category:Siltstone formations of the United States]]
[[Category:Sandstone formations of the United States]]

Nacimiento Formation - Revision history

imported>Volcanoguy: removed Category:Siltstone formations; added Category:Siltstone formations of the United States using HotCat