The Nacimiento Formation is a sedimentary rock formation found in the San Juan Basin of western New Mexico (United States). 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, deposited in floodplain, fluvial and lacustrine settings, and made up of sediment shed from the San Juan uplift to the north and the Brazos-Sangre de Cristo uplift to the east. It was deposited mostly between ~65.7 and ~61 million years ago, during the early and middle Paleocene. The climate was humid and warm to hot and stable, but with a distinct dry season. This unit interbeds with the underlying Ojo Alamo Formation but is separated by an unconformity from the overlying San Jose Formation.
The Nacimiento Formation is divided into several subunits known as 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. In northern outcrops, the two lower members are indistinguishable, and are called the "main body". Above them are two more informal members. These preserve a younger, Tiffanian fauna. The Puercan and Torrejonian faunas are further subdivided into several biostratigraphic zones.
Fossils
Many fossils are known from the Nacimiento Formation, although bone is often altered into phosphatic concretions. Fossils belonging to a number of different organisms have been found here, including: plants (mostly dicotyledonous angiosperms),[10] gastropods, freshwater bivalves, cartilaginous fish and bony fish, salamanders, turtles, champsosaurs, amphisbaenians, lizards, snakes, crocodilians, birds, and a variety of archaic mammals. Mammalian groups represented include multituberculates, plesiadapiforms, didelphid marsupials, insectivorans, carnivorans, taeniodonts, mesonychians, condylarths, and cimolestans. Fossil remains found in the formation support the validity of the genus Thylacodon and the species T. montanensis.
These fossils provide important clues to the impact of the Cretaceous–Paleogene extinction event on mammals 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.
Fossil content
Based on the Paleobiology Database:[18]Template:Paleobiota-key-compact
Bony fish
| Boney Fish of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
| Lepisosteidae indet.
|
|
|
Torrejonian
|
|
A gar of uncertain affinities.
|
|
Amphibians
Reptiles
Turtles
| Turtles of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
| Adocus
|
A. hesperius
|
|
Puercan
|
|
An adocid turtle.
|
frameless
|
| A. onerosus
|
|
Torrejonian
|
|
| Axestemys
|
A. montinsana
|
|
Puercan[19]
|
|
A softshell turtle.
|
frameless
|
| Compsemys
|
C. victa
|
|
Puercan/Torrejonian
|
|
A compsemydid turtle.
|
|
| "Emys"
|
"E." sp.
|
|
Puercan/Torrejonian
|
|
A pond turtle.
|
|
| Hutchemys
|
H. acupictus
|
|
Puercan[19]
|
|
A plastomenid stem-softshell turtle.
|
|
| Hoplochelys
|
H. crassa
|
|
Puercan/Torrejonian
|
|
A kinosternoid turtle. Type locality of species.
|
|
| Neurankylus
|
N. cf. eximius
|
|
Puercan
|
|
A baenid turtle. Type locality of N. torrejonensis.
|
frameless
|
| N. torrejonensis
|
|
Torrejonian, potentially Puercan
|
|
| Plastomenus
|
P. vegetus
|
|
Puercan
|
|
A plastomenid stem-softshell turtle.[20]
|
|
| "Platypeltis"
|
"P." antiqua
|
|
Torrejonian
|
|
A stem-softshell turtle. Nomen dubium.[19]
|
|
| "Trionyx" (=Paleotrionyx)
|
"T." eloisae
|
|
Puercan
|
|
A softshell turtle. Type locality of species.[19]
|
|
| "T." reesidei
|
|
|
|
| "T." singularis
|
|
|
|
Squamates
| Squamates of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
| Glyptosaurinae indet.
|
|
|
Puercan & Torrejonian
|
|
A glyptosaurine anguid of uncertain affinities.
|
|
| Helagras
|
H. prisciformis
|
|
Puercan
|
|
A snake, the largest known Early Paleocene snake.[21]
|
|
| Machaerosaurus
|
M. torrejonensis
|
|
Torrejonian
|
|
A glyptosaurine anguid.
|
|
| Odaxosaurus
|
O. piger
|
|
Puercan
|
|
A glyptosaurine anguid.
|
|
| Parodaxosaurus
|
P. sanjuanensis
|
|
Torrejonian
|
|
A glyptosaurine anguid.
|
|
| Plesiorhineura
|
P. tsentasi
|
|
Torrejonian
|
|
A rhineurid worm lizard.
|
|
| Proxestops
|
P. silberlingii
|
|
Puercan & Torrejonian
|
|
A glyptosaurine anguid.
|
|
Birds
| Birds of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
| Tsidiiyazhi
|
T. abini
|
|
Torrejonian
|
|
A relative of the mousebirds.[22]
|
|
Mammals
Carnivorans
| Carnivorans of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
|
|
|
|
|
|
|
|
Cimolestans
| Cimolestans of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
|
|
|
|
|
|
|
|
Condylarths
| Condylarths of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
|
|
|
|
|
|
|
|
Insectivorans
| Insectivorans of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
|
|
|
|
|
|
|
|
Marsupials
| Marsupials of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
|
|
|
|
|
|
|
|
Mesonychians
| Mesonychians of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
|
|
|
|
|
|
|
|
Multituberculates
| Multituberculates of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
|
|
|
|
|
|
|
|
Pantodonts
| Pantodonts of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
|
|
|
|
|
|
|
|
| Plesiadapiforms of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
|
|
|
|
|
|
|
|
Reptiles
Molluscs
Bivalves
| Bivalves of the Nacimiento Formation
|
| Genus
|
Species
|
Location
|
Stratigraphic position
|
Material
|
Notes
|
Images
|
Gastropods
| 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.[23]
Workers in the early 1900s divided the rocks of the Nacimiento Formation into two formations, the lower Puerco Formation and the upper Torrejon Formation. This was rejected on the grounds that there were no 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. 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.
- ↑ Anderson 1960.
- ↑ "PBDB Strata Results". https://paleobiodb.org/classic/displayStrata?geological_group=&formation=Nacimiento&group_formation_member=Nacimiento.
- ↑ 19.0 19.1 19.2 19.3 Vitek, Natasha S.; Joyce, Walter G. (2015). "A Review of the Fossil Record of New World Turtles of the Clade Pan-Trionychidae" (in en). Bulletin of the Peabody Museum of Natural History 56 (2): 185–244. doi:10.3374/014.056.0204. ISSN 0079-032X. http://www.bioone.org/doi/10.3374/014.056.0204.
- ↑ Lyson, Tyler R.; Petermann, Holger; Miller, Ian M. (2021-01-02). "A new plastomenid trionychid turtle, Plastomenus joycei , sp. nov., from the earliest Paleocene (Danian) Denver Formation of south-central Colorado, U.S.A.". Journal of Vertebrate Paleontology 41 (1). doi:10.1080/02724634.2021.1913600. ISSN 0272-4634.
- ↑ Longrich, Nicholas R.; Bhullar, Bhart-Anjan S.; Gauthier, Jacques A. (2012-12-26). "Mass extinction of lizards and snakes at the Cretaceous–Paleogene boundary". Proceedings of the National Academy of Sciences 109 (52): 21396–21401. doi:10.1073/pnas.1211526110. PMID 23236177. PMC 3535637. https://www.pnas.org/doi/full/10.1073/pnas.1211526110.
- ↑ Ksepka, Daniel T.; Stidham, Thomas A.; Williamson, Thomas E. (2017-07-25). "Early Paleocene landbird supports rapid phylogenetic and morphological diversification of crown birds after the K–Pg mass extinction". Proceedings of the National Academy of Sciences 114 (30): 8047–8052. doi:10.1073/pnas.1700188114. PMID 28696285. PMC 5544281. https://www.pnas.org/doi/full/10.1073/pnas.1700188114.
- ↑ Wheeler, George; White, Charles; Cope, Edward (1877). "Report upon United States geological surveys west of the one hundredth meridian, Volume IV: Paleontology". US Government Printing Office. https://pubs.er.usgs.gov/publication/70039253.
References
- Anderson, R.Y. (1960). Cretaceous-Tertiary palynology, eastern side of the San Juan Basin, New Mexico. Memoir 6. Socorro, New Mexico: New Mexico Bureau of Mines and Mineral Resources. https://geoinfo.nmt.edu/publications/monographs/memoirs/downloads/6/Memoir-6.pdf. Retrieved 8 June 2020.
- Davis, Adam J.; Peppe, Daniel J.; Atchley, Stacy C.; Williamson, Thomas E.; Flynn, Andrew G. (December 2016). "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". Palaeogeography, Palaeoclimatology, Palaeoecology 463: 27–44. doi:10.1016/j.palaeo.2016.09.011. Bibcode: 2016PPP...463...27D.
- Fassett, J.E. (1992). "Cretaceous and Tertiary rocks of the eastern San Juan Basin, New Mexico and Colorado". in Siemers, C.T.. Ghost Ranch. New Mexico Geological Society Guidebook. 25. Socorro, New Mexico: New Mexico Geological Society. pp. 225–230.
- Gardner, J.H. (1910). "The Puerco and Torrejon formations of the Nacimiento Group". Journal of Geology 18 (8): 702–741. doi:10.1086/621799. Bibcode: 1910JG.....18..702G.
- Hartman, J.H. (1981). "Early Tertiary nonmarine Mollusca of New Mexico: a review". Geological Society of America Bulletin 92 (12): I 942–I 950. doi:10.1130/0016-7606(1981)92<942:ETNMON>2.0.CO;2. Bibcode: 1981GSAB...92..942H.
- Leslie, Caitlin; Peppe, Daniel; Williamson, Thomas; Bilardello, Dario; Heizler, Matthew; Secord, Ross; Leggett, Tyler (March 2018). "High-resolution magnetostratigraphy of the Upper Nacimiento Formation, San Juan Basin, New Mexico, USA: Implications for basin evolution and mammalian turnover". American Journal of Science 318 (3): 300–334. doi:10.2475/03.2018.02. Bibcode: 2018AmJS..318..300L. https://osf.io/qxw4n/.
- Libed, S.A. (2005). Lithostratigraphy and mammalian biostratigraphy of the Torrejonian-Tiffanian transition in the Nacimiento Formation, northwestern San Juan Basin, New Mexico. M.A. thesis. Albuquerque, New Mexico: University of New Mexico.
- Lucas, S.G. (1984). "Correlation of Eocene rocks of the northern Rio Grande Rift and adjacent areas: implications for Laramide tectonics". in Baldridge, W.S.. Rio Grande Rift: northern New Mexico. New Mexico Geological Society Guidebook. 35. Socorro, New Mexico: New Mexico Geological Society. pp. 123–128. https://nmgs.nmt.edu/publications/guidebooks/downloads/35/35_p0123_p0128.pdf. Retrieved 8 June 2020.
- Lucas, S.G.; Ingersoll, R.V. (1981). "Cenozoic continental deposits of New Mexico: an overview". Geological Society of America Bulletin 92 (12): I 917–I 932, II 1807–II 1981. doi:10.1130/0016-7606(1981)92<917:CCDONM>2.0.CO;2. Bibcode: 1981GSAB...92..917L.
- Schoch, R.M. (1981). "Taxonomy and biostratigraphy of the early Tertiary Taeniodonta (Mammalia: Eutheria)". Geological Society of America Bulletin 92 (12): I 933-I 941, II 1982-II 2267. doi:10.1130/gsab-p2-92-1982. Bibcode: 1981GSAB...92.1982S.
- Silcox, Mary T.; Williamson, Thomas E. (December 2012). "New discoveries of early Paleocene (Torrejonian) primates from the Nacimiento Formation, San Juan Basin, New Mexico". Journal of Human Evolution 63 (6): 805–833. doi:10.1016/j.jhevol.2012.09.002. PMID 23084622.
- Simpson, G.G. (1959). "Fossil mammals from the type area of the Puerco and Nacimiento strata, Paleocene of New Mexico". American Museum Novitates (1957). http://digitallibrary.amnh.org/bitstream/handle/2246/2497/N1957.pdf?sequence=1. Retrieved 8 June 2020.
- Sullivan, R.M.; Lucas, S.G. (1986). "Annotated list of fossil vertebrates from the Paleocene Nacimiento Formation (Puercan-Torrejonian), San Juan Basin, New Mexico". Journal of Herpetology 20 (2): 202–209. doi:10.2307/1563945.
- Tidwell, W.D.; Ash, S.R.; Parker, L.R. (1981). "Cretaceous and Tertiary floras of the San Juan Basin". in Lucas, S.G.. Advances in San Juan Basin paleontology. Albuquerque, New Mexico: University of New Mexico Press. pp. 307–332. ISBN 0-8263-0554-7.
- Williamson, T.E. (1996). The beginning of the age of mammals in the San Juan Basin, New Mexico: biostratigraphy and evolution of Paleocene mammals of the Nacimiento Formation. New Mexico Museum of Natural History and Science Bulletin, 8. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. https://nmdigital.unm.edu/digital/collection/bulletins/id/1210/. Retrieved 8 June 2020.
- Williamson, Thomas E.; Brusatte, Stephen L.; Carr, Thomas D.; Weil, Anne; Standhardt, Barbara R. (1 December 2012). "The phylogeny and evolution of Cretaceous–Palaeogene metatherians: cladistic analysis and description of new early Palaeocene specimens from the Nacimiento Formation, New Mexico". Journal of Systematic Palaeontology 10 (4): 625–651. doi:10.1080/14772019.2011.631592.
- Williamson, Thomas E.; Brusatte, Stephen L.; Secord, Ross; Shelley, Sarah (May 2016). "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". Zoological Journal of the Linnean Society 177 (1): 183–208. doi:10.1111/zoj.12336.
- Williamson, T.E.; Lucas, S.G. (1992). "Stratigraphy and mammalian biostratigraphy of the Paleocene Nacimiento Formation, southern San Juan basin, New Mexico". in Lucas, S.G.. San Juan Basin IV. New Mexico Geological Society Guidebook. 43. Socorro, New Mexico: New Mexico Geological Society. pp. 265–296. ISBN 99922-2-673-0. https://nmgs.nmt.edu/publications/guidebooks/downloads/43/43_p0265_p0296.pdf. Retrieved 26 August 2020.
Template:Chronostratigraphy of Colorado
 | Original source: https://en.wikipedia.org/wiki/Nacimiento Formation. Read more |
