Plionarctos

Plionarctos
Temporal range: Late Miocene - Late Pliocene
Plionarctos jawbone from the Rattlesnake Formation, Oregon.
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Caniformia
Infraorder: Arctoidea
Family: Ursidae
Subfamily: Tremarctinae
Genus: †
Frick, 1926
Type species
†Plionarctos edensis
Frick, 1926
Species

†P. edensis Frick, 1926
†P. harroldorum Tedford & Martin, 2001

Plionarctos is an extinct genus of short-faced bear endemic to North America from the Late Miocene to the Pliocene.

Taxonomy

Described by Childs Frick in 1926,[1] Plionarctos is the oldest known genus within the subfamily of the short-faced bears (Tremarctinae),[2][3][4] and is believed to be ancestral to Arctodus, Arctotherium and Tremarctos.[5] Once suggested to have emerged from the Ursavine bears (Agriotherium and Indarctos),[6] Plionarctos probably evolved from Ursavus which emigrated into North America from Eurasia during the Miocene,[7] or possibly Protarctos.[8] A new species, Plionarctos harroldum, was described in 2001 from the White Bluffs Fauna in Washington from remains previously attributed to Protarctos abstrusus.[5] Middle Pleistocene species from France were described (Plionarctos stehlini and Plionarctos telonensis) but have since been reassigned & synonymized with the Asian black bear (Ursus thibetanus).[9][10][11][12]

Diagnostics

Tremarctinae

Various dental characteristics link Plionarctos with other tremarctine bears, such as a deep mandible underneath the molars, a notable groove underneath the premolars, a massateric fossa at its deepest in line with the teeth, an M1 molar with a labial enamel bulge and high talonid with a very shallow basin, and a rectangular M2 molar.[5]

Archaic characteristics which separate Plionarctos from other tremarctines such as Arctodus and Tremarctos include a lack of a premasseteric fossa (and the associated extension of the strongly ridged masseteric crest) and a tri-rooted (rather than birooted) P4 premolar, with its protocone anterior (instead of behind) the carnassial notch.[5]

Tremarctos

In addition to the lack of premasseteric fossa in Plionarctos, the M2 molar of Plionarctos is slightly shorter than that of Tremarctos (though tooth sizes are similar).[3]

Plionarctos

Plionarctos harroldorum shares dental characteristics with Tremarctos, with both lacking a well-defined lingual cinguli, and a longer and wider talon on the M2, which is not as dorsal as Plionarctos edensis. The M2 of P. harroldorum is broad compared to the width of M1 with a longer talonid than in P. edensis.[5]

Evolution

Tremarctinae within Ursidae

†Hemicyoninae

†Ursavinae

Ailuropodinae

Ursinae

Tremarctinae (short-faced bears)

†Plionarctos

Likely part of the Hemphillian 2 migration wave (Hh2) across the Beringinian land bridge in the late early Miocene,[13] Plionarctos first appeared in North America (during the late Miocene epoch) being recorded from the Rattlesnake Formation of Oregon circa 7Ma.[3] The Hh2 migration was the largest migration wave of Carnivorans between Asia into North America, and was also one of the largest mammalian dispersal events of the Neogene. The ascendancy of Asian fauna in this exchange may have been due to the intensification of the monsoon season in northeastern Asia expanding humid forests into the Arctic (in contrast to the global trend of aridification and expansion of C4 grasslands), with the more static & arid ecologies of North America potentially acting as refugia for Asian fauna.[13]

Due to the ecological diversity of the fauna, the Beringian corridor during the Hh2 migration event is believed to have been a mix of grasslands and forests. Bears were the largest faunal group, with over five species appearing in North America (representing almost all known genera of the period), with their omnivory, locomotive benefits due to large size and overall adaptability likely contributing to their success.[13] Notable fauna within the Hh2 wave includes Plionarctos, Amphimachairodus, Enhydritherium, Indarctos, and Simocyon.[14]

Plionarctos was the sole representative of the Tremarctinae subfamily of bears during its existence, with P. edensis being thought to be ancestral to P. harroldorum.[5] Both Plionarctos edensis and Plionarctos harroldorum coexisted in the Late Hemphillian faunal stage of the Late Miocene, although only P. harroldorum is confirmed from the Blancan faunal stage.[5]

Plionarctos is last recorded ca. 2.9Ma from Taunton, Washington, from a specimen which appears to be evolutionarily intermediate between Plionarctos harroldum and Tremarctos floridanus.[5][15] Plionarctos was followed by three new genera of short-faced bear around the Plio-Pleistocene boundary.[16] These were Arctodus (pristinus), Tremarctos (floridanus) and Arctotherium sp., which emerged in the Late Blancan age of North America circa 2.6Ma.[17][18][19]

An investigation into the mitochondrial DNA of bear species indicates that the short-faced bears diverged from the Ursinae subfamily approximately 5.7 million years ago.[20][21] Around the Miocene-Pliocene boundary (~5.3 Ma) short-faced bears, along with other ursids, experienced an explosive radiation in diversity, as C4 vegetation (grasses) and open habitats dominated, the world experienced a major temperature drop and increased seasonality, and a faunal turnover which extinguished 60–70% of all Eurasian faunal genera, and 70–80% of North American genera.[22][23] Correspondingly, the three succeeding genera appear to genetically diverge around this time, with Arctodus splitting from Arctotherium and Tremarctos at between 5.5Ma and 4.8Ma,[16][24] and Arctotherium and Tremarctos branching off at 4.1Ma.[16]

Description

Plionarctos is thought to have weighed around the size of a smaller spectacled bear (60–150 kg), and a skull length of 20 cm.[3] Postcranial skeletons of Plionarctos are unknown.[3] Like other tremarctine bears, Plionarctos is believed to have been sexually dimorphic.[3] The Rattlesnake Formation specimen of P. edensis was calculated to 116 kg,[25] while a P. harroldorum individual from Washington was calculated to 165.5 kg.[26]

Map of fossil localities

Plionarctos is located in North America
Rattlesnake Formation (Hemphillian)
Montbrook Site (Plionarctos sp.)
Eden Formation (type P. edensis, Hemphillian), Aguanga Horizon (Plionarctos sp.? Blancan)
Gray Fossil Site (Plionarctos sp., Hemphillian)
Pipe Creek Sinkhole (latest Hemphillian or earliest Blancan)
Walnut Canyon
Fort Green Mine, Gardinier Mine, Palmetto Mine (Plionarctos sp., Palmetto Fauna, Hemphillian)
Bear Springs (Early Blancan)
Ash Hollow Formation (Hemphillian)
White Bluffs fauna (type P. harroldorum, Early Blancan) & Taunton site (Blancan)
Interactive distribution map of Plionarctos (hover over dots for locality information)

Legend: P. edensis P. harrolodum

Plionarctos sp.

Fossil distribution

Plionarctos existed between the middle Hemphillian faunal stage to the Blancan faunal stage (7Mya - 2.9Mya).[3][27] Present on the coasts but rare in the Interior Plains, Plionarctos is thought to have preferred more humid forested habitats.[3] The geologic range of Plionarctos (along with Teleoceras) correspond with the Late Miocene and Early Pliocene, which saw the expansion of C4 grasslands and was characterized by open prairie and North American faunas rich in horses, camels, and antilocaprids. The presence of Plionarctos and Teleoceras have been used to constrain the temporal ages of the Gray Fossil Site, Palmetto Fauna and the Pipe Creek Sinkhole to the Hemphillian (between 7Mya and 4.5Mya, late Miocene to early Pliocene),[28][29] however specimens of these index fossils younger than 4.5Mya put this temporal bracketing in doubt.[30]

Western Mountains

The type specimen of Plionarctos edensis was recovered from the Mt. Eden Formation of the Pacific Mountain System (Riverside County, California) and dates to the Hemphillian faunal stage (5.6Mya).[3][31] Another individual (originally described as P. edensis) was also recovered from Riverside County (Aguanga Horizon, Blancan faunal stage).[3]

Intermontane Plateaus

Reconstruction of the Rattlesnake Formation.

The oldest known specimen of Plionarctos (P. edensis) comes from the Rattlesnake Formation of the Intermontane Plateaus (Oregon, Hemphillian ca. 7Mya),[3] alongside remains of Lutravus halli, "Hipparion sp.", and "Sphenophalos" sp.[5][32] A sagebrush steppe with semi-arid wooded shrubland and tall grasslands, the Rattlesnake Formation fauna is considered a reference fauna for the Hemphillian faunal age.[32] Being close to the Beringian land bridge, the Rattlesnake Formation preserves the earliest North American records of immigrant taxa from Asia, such as Plionarctos, Lutravus, Simocyon, and the fellow bear Indarctos.[33] These fauna were recovered alongside Megalonyx, Amebelodon, Hemiauchenia, Megatylopus, Pliauchenia, Ilingoceras, Pediomeryx, Parablastomeryx, Mylohyus, Platygonus, Teleoceras, Hippotherium, Neohipparion, Pliohippus, Borophagus secundus, Borophagus pugnator, Eucyon, Metalopex, Vulpes, Lynx, Rhizosmilodon, and Nimravides. The presence of Castor californicus, Dipoides, Pekania, and an unidentified tapir suggest riparian forests also existed in this ecosystem.[32][33] Plionarctos sp. has also been tentatively assigned to a toe bone recovered from Walnut Canyon, New Mexico (latest Hemphilian, late Miocene).[34][35]

Conversely, the youngest representatives of Plionarctos have also been recovered from the Ringold Formation of Washington (White Bluffs & Taunton, Early & Late Blancan respectively). The White Bluffs specimen is the type specimen of P. harroldorum,[5] while the Taunton individual is the youngest known P. harroldorum specimen, being dated to 2.9Mya.[5][15] As the Taunton specimen is larger and has anatomical convergences with Tremarctos floridanus (having been initially identified as T. floridanus), the Taunton specimen may represent a transitional form between P. harroldorum and T. floridanus.[5] The Taunton locality suggests that the Columbia Basin resembled the coastal Klamath Mountains of Oregon, which is dominated by conifers with a milder and moister climate (particularly the winters).[36] Recovered from a freshwater fluvial environment, the Taunton P. harroldorum was preserved alongside numerous bony fish, turtles, waterfowl, Equus simplicidens and Capromeryx, along with Megalonyx, Platygonus, Camelops, Hemiauchenia, Dinofelis cf. paleonca, Borophagus, Canis lepophagus, Puma lacustris and cervids.[15] An additional P. harroldorum has been recovered from Bear Springs, Arizona (Early Blancan Red Knolls Fauna, ca. 3.1Mya).[37][38]

Interior Plains

The Pipe Creek Sinkhole of the Interior Plains (Indiana, 4-5Mya, latest Hemphillian or earliest Blancan) preserves a wetland environ which was surrounded by a dry, open herbaceous savanna with some denser vegetation (such as Fagus, Platanus, Populus and Salix), representing an extension of the Early Pliocene Great Plains. The site records abundant leopard frogs and pond turtles, but also Plionarctos edensis, Borophagus sp., Vulpes, Canis sp., Castor, Spermophilus, deer, Hemiauchenia, Aepycamelus, Titanotylopus and Teleoceras.[39] The Hemphillian-age Ash Hollow Formation (Ogalla / Bear Tooth Slide, Nebraska) preserves Plionarctos sp. close to but distinguished from Plionarctos edensis.[5][3]

Appalachian Highlands

Gray Fossil Site & Museum.

The Gray Fossil Site (ca. 4.5 - 4.9 Mya, latest Hemphillian or earliest Blancan, Appalachian Highlands) of Tennessee was a lacustrine sinkhole situated in a dry & mesic oak-hickory woodland / savanna, which also included pine, walnut, and a herbaceous forb understory. Often associated with periodic fires, the herbaceous understory may also indicate a patchy canopy.[40][29] Surrounded by expanding Miocene grasslands, the Gray Fossil Site acted as a refugium of dense vegetation for browsers and mixed feeders (though there was a noticeable lack of large mammalian predators).[28] Plionarctos sp. was recovered alongside many aquatic animals such as alligators, salamanders, fish, turtles, beavers and tapirs, along with Mammut, Teleoceras, Megatylopus, Pristinailurus, Mylohyus, Prosthennops, Arctomeles, Gulo, Borophagus and saber-toothed cats.[28][30][41][42][43] The Pipe Creek Sinkhole and Palmetto Fauna are the most biologically similar sites to the Gray Fossil Site.[28][41]

Atlantic Plain

Teleoceras is often found in association with Plionarctos.

The Palmetto Fauna of the upper Bone Valley Formation (4.5 - 5Mya, Hemphillian faunal age, Florida) is the largest and best known late Hemphillian land vertebrate assemblage in the eastern United States.[44] Dating to the early Pliocene of the Atlantic Plain, the Palmetto fauna resembled an archaic Clarendonian faunal assemblage from the Interior Plains (ca. 10Mya) due to its breadth & diversity of browsing, mixed-feeding, and grazing herbivores. 19 specimens of Plionarctos sp. have been recovered from the Fort Green, Palmetto, and Gardinier mines.[3][41][45] Together with Agriotherium, bears make up 22% of carnivoran teeth & jaws in the Palmetto Fauna.[45]

Floridan Plionarctos sp. has been distinguished from P. edensis but is currently unassigned.[5][45] Additional fauna includes Hesperotestudo, Amphimachairodus, Rhizosmilodon, Lynx, Vulpes, Borophagus hilli, Borophagus pugnator, Carpocyon, Eucyon, Arctonasua, Enhydritherium, Megalonyx, Rhynchotherium, Gomphotherium, Mammut, Aphelops, Teleoceras, Astrohippus, Cormohipparion, Dinohippus, Nannippus, Neohipparion, Pseudhipparion, Hexameryx, Kyptoceras, Catagonus, Mylohyus, Tapirus polkensis, Antilocapra, Hemiauchenia, and Megatylopus,[44][45] along with one of the oldest species of deer (Eocoileus) in North America.[46] Although half the species recovered also occurred in late Hemphillian faunas of the western United States and Mexico (Mount Eden, California; Santee, Nebraska; Buis Ranch, Oklahoma; Yepómera, Chihuahua; El Ocoté, Guanajuato), the more humid & forested site also preserves many endemic southeastern species (particularly ungulates), along with marine fauna such as sharks, rays, and cetaceans.[44][45] Due to higher sea levels, the Florida Peninsula was only about 5% of its present land area.[45] Plionarctos sp. has also been recovered from Montbrook Site (Plionarctos sp., 5 - 5.5 Mya, Florida).[47][48]

References

  1. ^ Frick, Childs (1926). "The Hemicyoninæ and an American Tertiary Bear". Bulletin of the American Museum of Natural History. 56 (1): 111–119. hdl:2246/1321.
  2. ^ Mitchell, K. J.; Bray, S. C.; Bover, P.; Soibelzon, L.; Schubert, B. W.; Prevosti, F.; Prieto, A.; Martin, F.; Austin & Alan Cooper, J. J. (2016). "Ancient mitochondrial DNA reveals convergent evolution of giant short-faced bears (Tremarctinae) in North and South America". Biology Letters. 12 (4): 20160062. doi:10.1098/rsbl.2016.0062. PMC 4881349. PMID 27095265.
  3. ^ a b c d e f g h i j k l m Hunt Jr., Robert M. (1998-05-28). "Chapter 10: Ursidae". In Janis, Christine M.; Scott, Kathleen M.; Jacobs, Louis L. (eds.). Evolution of Tertiary Mammals of North America: Volume 1, Terrestrial Carnivores, Ungulates, and Ungulate Like Mammals. Cambridge University Press. ISBN 978-0-521-35519-3.
  4. ^ Carroll, Robert Lynn (1988). Vertebrate paleontology and evolution. New York, N.Y: Freeman. ISBN 978-0-7167-1822-2.
  5. ^ a b c d e f g h i j k l m n Tedford, Richard H.; and Martin, James (2001-07-20). "Plionarctos, a tremarctine bear (Ursidae: Carnivora) from western North America". Journal of Vertebrate Paleontology. 21 (2): 311–321. doi:10.1671/0272-4634(2001)021[0311:PATBUC]2.0.CO;2. ISSN 0272-4634.
  6. ^ Samuels, Joshua X.; Meachen-Samuels, Julie A.; Gensler, Philip A. (July 2009). "The first Mid-Blancan occurrence of Agriotherium (Ursidae) In North America: A record from Hagerman Fossil Beds National Monument, Idaho". Journal of Paleontology. 83 (4): 597–603. doi:10.1666/08-112R.1. ISSN 0022-3360.
  7. ^ Figueirido, Borja; Soibelzon, Leopoldo H. (June 2010). "Inferring palaeoecology in extinct tremarctine bears (Carnivora, Ursidae) using geometric morphometrics". Lethaia. 43 (2): 209–222. Bibcode:2010Letha..43..209F. doi:10.1111/j.1502-3931.2009.00184.x. ISSN 0024-1164.
  8. ^ Wang, Xiaoming; Rybczynski, Natalia; Harington, C. Richard; White, Stuart C.; Tedford, Richard H. (2017-12-18). "A basal ursine bear (Protarctos abstrusus) from the Pliocene High Arctic reveals Eurasian affinities and a diet rich in fermentable sugars". Scientific Reports. 7 (1): 17722. Bibcode:2017NatSR...717722W. doi:10.1038/s41598-017-17657-8. ISSN 2045-2322. PMC 5735171. PMID 29255278.
  9. ^ Cregut-Bonnoure, Evelyne (15 August 1996). "A review of small Middle Pleistocene bears from France" (PDF). Acta Zoologica Cracoviensia. 39 (1): 89–101.
  10. ^ Villalba de Alvarado, Mónica; Crégut-Bonnoure, Evelyne; Arsuaga, Juan Luis; Collado Giraldo, Hipólito; van der Made, Jan; Gómez-Olivencia, Asier (2024-02-01). "Pleistocene Asian black bear (Ursus thibetanus Cuvier, 1823) in the Iberian Peninsula: new evidence and a complete review". Quaternary Science Reviews. 325: 108385. doi:10.1016/j.quascirev.2023.108385. ISSN 0277-3791.
  11. ^ Pappa, Spyridoula (2016). "Palaeoecology and Palaeodiet: reconstructing adaptations in the Middle and Late Pleistocene Ursidae through dental microwear and geochemistry" (PDF). Royal Holloway, University of London (PhD thesis).
  12. ^ "First Discovery of Ursus Thibetanus (Mammalia, Carnivora, Ursidae) in the Gajtan Site (Shkoder) North Albania". Journal of Vertebrate Paleontology: Abstract of Papers. Fifty-Third Annual Meeting. 13 (3): 35A. 1993. ISSN 0272-4634.
  13. ^ a b c Jiangzuo, Qigao; Wang, Shi-Qi (January 2023). "Northeastern Asia humidification at the end of the Miocene drives the boost of mammalian dispersals from the Old to New World". Journal of Palaeogeography. 12 (1): 50–68. doi:10.1016/j.jop.2022.09.002.
  14. ^ Jiangzuo, Qigao; Li, Shijie; Deng, Tao (December 2022). "Parallelism and lineage replacement of the late Miocene scimitar-toothed cats from the old and New World". iScience. 25 (12): 105637. doi:10.1016/j.isci.2022.105637. PMC 9730133. PMID 36505925.
  15. ^ a b c Morgan, James K.; Morgan, Neil H. (1995). "A New Species of Capromeryx (Mammalia: Artiodactyla) from the Taunton Local Fauna of Washington, and the Correlation with Other Blancan Faunas of Washington and Idaho". Journal of Vertebrate Paleontology. 15 (1): 160–170. Bibcode:1995JVPal..15..160M. doi:10.1080/02724634.1995.10011215. ISSN 0272-4634. JSTOR 4523614.
  16. ^ a b c Mitchell, Kieren J.; Bray, Sarah C.; Bover, Pere; Soibelzon, Leopoldo; Schubert, Blaine W.; Prevosti, Francisco; Prieto, Alfredo; Martin, Fabiana; Austin, Jeremy J.; Cooper, Alan (2016-04-30). "Ancient mitochondrial DNA reveals convergent evolution of giant short-faced bears (Tremarctinae) in North and South America". Biology Letters. 12 (4): 20160062. doi:10.1098/rsbl.2016.0062. PMC 4881349. PMID 27095265.
  17. ^ Emslie, Steven D. (1995). "The fossil record of Arctodus pristinus (Ursidae: Tremarctinae) in Florida" (PDF). Bulletin of the Florida Museum of Natural History. 37 (15): 501–514. doi:10.58782/flmnh.hduf9651. S2CID 168164209.
  18. ^ Soibelzon, Leopoldo H.; Romero, M.R. Aguilar (2008-10-14). "A Blancan (Pliocene) short-faced bear from El Salvador and its implications for Tremarctines in South America". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 250 (1): 1–8. doi:10.1127/0077-7749/2008/0250-0001.
  19. ^ Schubert, Blaine; Hulbert, Richard; MacFadden, Bruce; Searle, Michael; Searle, Seina (2010-01-01). "Giant Short-faced Bears (Arctodus simus) in Pleistocene Florida USA, a Substantial Range Extension". Journal of Paleontology. 84 (1): 79–87. Bibcode:2010JPal...84...79S. doi:10.1666/09-113.1. S2CID 131532424.
  20. ^ Krause, Unger (2008). "Mitochondrial genomes reveal an explosive radiation of extinct and extant bears near the Miocene-Pliocene boundary". BMC Evolutionary Biology. 8 (1): 220. Bibcode:2008BMCEE...8..220K. doi:10.1186/1471-2148-8-220. PMC 2518930. PMID 18662376.
  21. ^ Yu, Li (2007). "Analysis of complete mitochondrial genome sequences increases phylogenetic resolution of bears (Ursidae), a mammalian family that experienced rapid speciation". BMC Evolutionary Biology. 7 (1): 198. Bibcode:2007BMCEE...7..198Y. doi:10.1186/1471-2148-7-198. PMC 2151078. PMID 17956639.
  22. ^ Krause, Johannes; Unger, Tina; Noçon, Aline; Malaspinas, Anna-Sapfo; Kolokotronis, Sergios-Orestis; Stiller, Mathias; Soibelzon, Leopoldo; Spriggs, Helen; Dear, Paul H.; Briggs, Adrian W.; Bray, Sarah CE (2008-07-28). "Mitochondrial genomes reveal an explosive radiation of extinct and extant bears near the Miocene-Pliocene boundary". BMC Evolutionary Biology. 8 (1): 220. Bibcode:2008BMCEE...8..220K. doi:10.1186/1471-2148-8-220. ISSN 1471-2148. PMC 2518930. PMID 18662376.
  23. ^ Donohue, Shelly L.; DeSantis, Larisa R. G.; Schubert, Blaine W.; Ungar, Peter S. (30 October 2013). "Was the giant short-faced bear a hyper-scavenger? A new approach to the dietary study of ursids using dental microwear textures". PLOS ONE. 8 (10): e77531. Bibcode:2013PLoSO...877531D. doi:10.1371/journal.pone.0077531. PMC 3813673. PMID 24204860.
  24. ^ Pedersen, Mikkel Winther; De Sanctis, Bianca; Saremi, Nedda F.; Sikora, Martin; Puckett, Emily E.; Gu, Zhenquan; Moon, Katherine L.; Kapp, Joshua D.; Vinner, Lasse; Vardanyan, Zaruhi; Ardelean, Ciprian F. (2021-06-21). "Environmental genomics of Late Pleistocene black bears and giant short-faced bears". Current Biology. 31 (12): 2728–2736.e8. Bibcode:2021CBio...31E2728P. doi:10.1016/j.cub.2021.04.027. hdl:10037/22808. PMC 7617452. PMID 33878301. S2CID 233303447.
  25. ^ Reuter, Dana M. (December 2021). "Trophic Structure Evolution in Oregon Oligo-Miocene Terrestrial Communities". University of Oregon (PhD Thesis).
  26. ^ McKenna, Ryan Thomas Paul (2011). "Potential for Speciation in Mammals Following Vast, Late Miocene Volcanic Interruptions in the Pacific Northwest". Portland State University (Masters' Thesis).
  27. ^ Hernández Jasso, R. E. (2017-06-30). "Dinámica de la estructura de comunidades del Cenozoico tardío de Norteamérica: Episodios de Recambio Rápido de Fauna (RTE) dentro del concepto de Cronofauna". Estudios Geológicos. 73 (1): e063. doi:10.3989/egeol.42668.434. ISSN 1988-3250.
  28. ^ a b c d Hawkins, Patrick (2011-05-01). "Variation in the Modified First Metatarsal of a Large Sample of Tapirus polkensis and the Functional Implications for Ceratomorphs". Electronic Theses and Dissertations.
  29. ^ a b Wallace, Steven C.; Wang, Xiaoming (30 September 2004). "Two new carnivores from an unusual late Tertiary forest biota in eastern North America" (PDF). Nature.
  30. ^ a b Samuels, Joshua X.; Bredehoeft, Keila E.; Wallace, Steven C. (2018). "A new species of Gulo from the Early Pliocene Gray Fossil Site (Eastern United States); rethinking the evolution of wolverines". PeerJ. 6: e4648. doi:10.7717/peerj.4648. ISSN 2167-8359. PMC 5910791. PMID 29682423.
  31. ^ Jiangzuo, Qigao; Wang, Shi-Qi (2023-01-01). "Northeastern Asia humidification at the end of the Miocene drives the boost of mammalian dispersals from the Old to New World". Journal of Palaeogeography. 12 (1): 50–68. doi:10.1016/j.jop.2022.09.002. ISSN 2095-3836.
  32. ^ a b c Graham, John P. (August 2014). "John Day Fossil Beds National Monument: Geologic Resources Inventory Report" (PDF). Natural Resource Report NPS/NRSS/GRD/NRR—2014/846. NPS 177/126139, August 2014.
  33. ^ a b Bredehoeft, Keila; Samuels, Joshua (October 2015). "Carnivora from the Rattlesnake Fauna (Early Hemphillian, Late Miocene) of Oregon" (PDF). Society of Vertebrate Paleontology, 75th Annual Meeting.
  34. ^ Morgan, Gary S. (October 25–27, 2012). "Late Cenozoic Vertebrate Faunas from the Gila Region of Southwestern New Mexico" (PDF). The New Mexico Botanist: Natural History of the Gila Symposium. Special Issue No. 4.
  35. ^ Jones, Amanda K. (July 2016). "Mammals of the Greater Gila Region" (PDF). The University of New Mexico Albuquerque, New Mexico (Thesis).
  36. ^ Parmley, Dennis; Walker, Don (2003). "Snakes of the Pliocene Taunton Local Fauna of Adams County, Washington with the Description of a New Colubrid". Journal of Herpetology. 37 (2): 235–244. ISSN 0022-1511.
  37. ^ White Jr., Richard S.; Morgan, Gary S. (2005). "Arizonan Blancan Vertebrate Faunas in Regional Perspective". Vertebrate Paleontology of Arizona, Mesa Southwest Museum Bulletin. 11.
  38. ^ Morgan, Gary S.; White Jr., Richard S. (2005). "Miocene and Pliocene vertebrates from Arizona". Vertebrate Paleontology in Arizona. New Mexico Museum of Natural History and Science Bulletin. 29 – via ResearchGate.
  39. ^ Farlow, James O.; Sunderman, Jack A.; Havens, Jonathan J.; Swinehart, Anthony L.; Holman, J. Alan; Richards, Ronald L.; Miller, Norton G.; Martin, Robert A.; Hunt, Robert M.; Storrs, Glenn W.; Curry, B. Brandon; Fluegeman, Richard H.; Dawson, Mary R.; Flint, Mary E.T. (2001). "The Pipe Creek Sinkhole Biota, a Diverse Late Tertiary Continental Fossil Assemblage from Grant County, Indiana". The American Midland Naturalist. 145 (2): 367–378. doi:10.1674/0003-0031(2001)145[0367:TPCSBA]2.0.CO;2. ISSN 0003-0031. JSTOR 3083113.
  40. ^ Zobaa, Mohamed K.; Zavada, Michael S.; Whitelaw, Michael J.; Shunk, Aaron J.; Oboh-Ikuenobe, Francisca E. (2011-08-01). "Palynology and palynofacies analyses of the Gray Fossil Site, eastern Tennessee: Their role in understanding the basin-fill history". Palaeogeography, Palaeoclimatology, Palaeoecology. 308 (3): 433–444. doi:10.1016/j.palaeo.2011.05.051. ISSN 0031-0182.
  41. ^ a b c Doughty, Evan M.; Wallace, Steven C.; Schubert, Blaine W.; Lyon, Lauren M. (2018). "First occurrence of the enigmatic peccaries Mylohyus elmorei and Prosthennops serus from the Appalachians: latest Hemphillian to Early Blancan of Gray Fossil Site, Tennessee". PeerJ. 6: e5926. doi:10.7717/peerj.5926. ISSN 2167-8359. PMC 6276594. PMID 30533292.
  42. ^ Hart-Farrar, Brenna (2019-12-01). "Manus Descriptions of an Undescribed Mastodon from the Latest Miocene-Earliest Pliocene Gray Fossil Site, with Comparisons to other North American Proboscidean Taxa". Electronic Theses and Dissertations.
  43. ^ Bōgner, Emily; Samuels, Joshua X. (November 2022). "The first canid from the Gray Fossil Site in Tennessee: new perspective on the distribution and ecology of Borophagus". Journal of Paleontology. 96 (6): 1379–1389. doi:10.1017/jpa.2022.46. ISSN 0022-3360.
  44. ^ a b c "Palmetto Fauna". Florida Vertebrate Fossils. Retrieved 2025-06-18.
  45. ^ a b c d e f Webb, S. David; Hulbert, Jr., Richard C.; Morgan, Gary S.; Evans, Helen F. (May 28, 2008). Wang, Xiaoming; Barnes, Lawrence G. (eds.). "Terrestrial mammals of the Palmetto Fauna (early Pliocene, latest Hemphillian) from the Central Florida Phosphate District". Geology and Vertebrate Paleontology of Western and Southern North America. Natural History Museum of Los Angeles County: Contributions in Honor of David P. Whistler (41): 293–312 – via ResearchGate.
  46. ^ "Oh Deer!". Montbrook Fossil Dig. 2017-02-25. Retrieved 2025-07-19.
  47. ^ "About Montbrook". Montbrook Fossil Dig. Retrieved 2025-06-18.
  48. ^ Ziegler, Michael; Jaeger, John M.; Steadman, David W.; Perez, Victor J.; MacFadden, Bruce J. MACFADDEN (2019). "Montbrook: Paleoenvironmental Analysis of an Unusual Fossil Locality from the Late Miocene in Northern Florida, USA". Society of Vertebrate Paleontology. doi:10.13140/RG.2.2.35869.26089.
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