Torrejonian

The Torrejonian North American Stage, on the geologic timescale, is a North American faunal stage within the North American Land Mammal Ages chronology (NALMA). It occupies part of the Paleocene epoch, covering an estimated age of about 65.1 to 62.3 million years ago. It is roughly equivalent to the later part of the Danian global stage (Early Paleocene).

The Torrejonian is preceded by the Puercan and followed by the Tiffanian NALMA stages. The Torrejonian-Tiffanian boundary is often correlated with the Danian-Selandian boundary (on the global timescale), the Shanghuan-Nongshanian boundary (in Asian land mammal ages), and the C27n-C26r polarity chron boundary (on the geomagnetic polarity time scale).

Mammal fauna

The Torrejonian marks the first appearance of many mammal groups in North America, including:

Substages

The Torrejonian contains the following three substages, from oldest to youngest:

Age

The oldest To1 fossils in New Mexico correlate to chron C28n. Farrand Channel and Horsethief Canyon, a pair of To1 sites in Montana, seem to be correlated to chron C28r, which would make them older than any other Torrejonian site. A 2009 study assigned a radiometric date of around 64.5 – 64.3 Ma to these sites, while a 2014 study published an even earlier estimate of around 65.12 – 65.04 Ma. Periptychus is unknown from these sites, and their estimated Torrejonian age is based on the presence of the paromomyid Paromomys instead. The oldest To1 fossils in Utah (the Dragon local fauna) are younger, correlated to the C28n-C27r boundary.

To2 sites appear to belong within chron C27r. In New Mexico, the To2-To3 boundary can be precisely dated to between 62.59 and 62.47 Ma, close to the boundary between C27r and C27n polarity chrons.

To3 is widely regarded as equivalent to C27n. Since Plesiadapis fossils have never been found in New Mexico, the end of To3 is impossible to precisely constrain in that area. A 2006 study offered an age of about 61.6 Ma for the end of the Torrejonian, based on a 2004 estimate for the end of C27n. As of 2020, the end of C27n has been recalibrated to 62.278 Ma, slightly older than the Danian-Selandian boundary.

Formations

The Torrejonian is named after the "Torrejon Formation", a defunct geological unit in the San Juan Basin of New Mexico. It is roughly equivalent to the Ojo Encino Member of the Nacimiento Formation, the current name in use for Paleocene strata of the San Juan Basin. Geological formations preserving Torrejonian fossils include:

References

  1. 1 2 Sprain, C. J.; Renne, P. R.; Wilson, G. P.; Clemens, W. A. (2015-03-01). "High-resolution chronostratigraphy of the terrestrial Cretaceous-Paleogene transition and recovery interval in the Hell Creek region, Montana". Geological Society of America Bulletin. 127 (3–4): 393–409. doi:10.1130/B31076.1. ISSN 0016-7606.
  2. 1 2 Speijer, R.P.; Pälike, H.; Hollis, C.J.; Hooker, J.J.; Ogg, J.G. (2020), "The Paleogene Period", Geologic Time Scale 2020, Elsevier, pp. 1087–1140, doi:10.1016/B978-0-12-824360-2.00028-0, ISBN 978-0-12-824360-2, retrieved 2026-08-30{{citation}}: CS1 maint: work parameter with ISBN (link)
  3. ↑ TINGSu-Yin; TONGYong-Sheng; C.clyde, William; L.koch, Paul; MENGJin; Yuan-Qing, Wang; J.bowen, Gabriel (2023-04-03). "ASIAN EARLY PALEOGENE CHRONOLOGY AND MAMMALIAN FAUNAL TURNOVER EVENTS". Vertebrata Palasiatica. 49 (1): 1. ISSN 2096-9899.
  4. 1 2 3 4 5 6 7 Lofgren, Donald L.; Lillegraven, Jason A.; Clemens, William A.; Gingerich, Philip D.; Williamson, Thomas E. (2004), "3. Paleocene Biochronology: The Puercan Through Clarkforkian Land Mammal Ages", in Woodburne, Michael O. (ed.), Late Cretaceous and Cenozoic Mammals of North America, Columbia University Press, pp. 43–105, doi:10.7312/wood13040-005, ISBN 978-0-231-13040-0, JSTOR 10.7312/wood13040.9, retrieved 2026-04-07
  5. 1 2 3 Leslie, Caitlin; Peppe, Daniel; Williamson, Thomas; Bilardello, Dario; Heizler, Matthew; Secord, Ross; Leggett, Tyler (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. ISSN 0002-9599.
  6. ↑ Clemens, William A.; Wilson, Gregory P. (2009). "Early Torrejonian mammalian local faunas from northeastern Montana, USA". Museum of Northern Arizona Bulletin. 65: 111–158.
  7. ↑ Hovatter, Brody T.; Chester, Stephen G.B.; Wilson Mantilla, Gregory P. (2024). "New records of early Paleocene (earliest Torrejonian) plesiadapiforms from northeastern Montana, USA, provide a window into the diversification of stem primates". Journal of Human Evolution. 192 103500. doi:10.1016/j.jhevol.2024.103500.
  8. ↑ Hovatter, Brody T.; Wilson Mantilla, Gregory P. (2026-08-03). "Early Paleocene (earliest Torrejonian) mammals from the Tullock Member of the Fort Union Formation, northeastern Montana, U.S.A.". Journal of Vertebrate Paleontology. doi:10.1080/02724634.2026.2688554. ISSN 0272-4634.
  9. ↑ Secord, R.; Gingerich, P. D.; Smith, M. E.; Clyde, W. C.; Wilf, P.; Singer, B. S. (2006-04-01). "Geochronology and Mammalian Biostratigraphy of Middle and Upper Paleocene Continental Strata, Bighorn Basin, Wyoming". American Journal of Science. 306 (4): 211–245. doi:10.2475/ajs.306.4.211. ISSN 0002-9599.
  10. ↑ Secord, Ross (2008-12-15). "The Tiffanian Land-Mammal Age (Middle and Late Paleocene) in the Northern Bighorn Basin, Wyoming". University of Michigan Papers in Paleontology. 35.
  11. ↑ Scott, Craig S. (2003). "Late Torrejonian (middle Paleocene) mammals from south central Alberta, Canada". Journal of Paleontology. 77 (4): 745–768. doi:10.1666/0022-3360(2003)077<0745:LTMPMF>2.0.CO;2. ISSN 0022-3360.