“Elephant-Equus” Event: History
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Contributor:
Alessio Iannucci
,
Raffaele Sardella

The dispersal of primitive elephantines and monodactyl equids in Eurasia has long been regarded as representative of a substantial turnover in mammal faunas, denoting the spread of open environments linked to the onset of cold and dry conditions in the Northern Hemisphere. During the 1980s, this event was named the “Elephant-Equus event” and it was correlated with the Gauss-Matuyama reversal, today corresponding to the Pliocene-Pleistocene transition and the beginning of the Quaternary, dated at ~2.6 Ma. Therefore, the Elephant-Equus event became a concept of prominent biochronological and paleoecological significance, especially in western Europe. Yet, uncertainties surrounding the taxonomy and chronology of early “elephant” and “Equus”, as well as conceptual differences in adopting (or understanding) the Elephant-Equus event as an intercontinental dispersal event or as a stratigraphic datum, engendered ambiguity and debate.

  • biochronology
  • bioevent
  • dispersal event
  • Equus Datum

1. Introduction

The beginning of the Quaternary Period is formally tied to 2.58 Ma, the age of the GSSP for the Gelasian Stage in the Monte San Nicola section in Italy, corresponding to the Gauss-Matuyama paleomagnetic reversal [1][2]. Around 2.7–2.6 Ma, the glacial activity of the Northern Hemisphere increased, and major climatic changes took place, basically resulting in a transition from long-term warm–humid conditions to large amplitude alternations between cool–arid and warm–humid environments [2][3][4][5]. The long-lasting trend of increasing cold and aridity observed during most of the Cenozoic and especially after the Mid-Miocene Climatic Optimum—of which the more humid and warmer conditions of the Early Pliocene were a small countertrend [6]—was now accompanied by oscillations between glacial and interglacial periods and, at a finer scale, by a more marked seasonality [7][8].
The important biotic response to these environmental changes has long been recognized and correlated to a transition from the early Villafranchian to the middle Villafranchian, in terms of mammal biochronology [9][10][11][12]. During the 1960s and the 1970s, the concept of biochronology was coming to age as a crucial approach for relating biological events to the geological time scale [13][14][15][16], alongside efforts aimed at identifying consistent subdivisions in the Villafranchian in western Europe (e.g., [9][10][17][18][19][20][21]).

2. Research on“Elephant-Equus” Event

Lindsay et al. [22] undertook paleomagnetic investigations of two stratigraphic sections in Italy yielding the Triversa (early Villafranchian, MN 16a) and Montopoli (middle Villafranchian, MN 16b) classic faunas. The results allowed the authors to correlate what is now identified as the early Villafranchian to middle Villafranchian transition—and the concurrent appearance of Equus Linnaeus, 1758 [23], and Mammuthus Brookes, 1828 [24]—with the Gauss-Matuyama reversal (today dated at ~2.6 Ma). To clarify the appearance of Equus and Mammuthus in Europe, Lindsay et al. [22] already recognized the necessity of more data on the 3.0–2.6 Ma timespan, and they further noted that “Biochronological-palaeomagnetic sequence studies [25] of the Ponto-Caspian Basin show the beginning of the Archidiskodon Superzone (equivalent to the appearance of Mammuthus, and possibly Equus) at the Mammoth event (about 3.1 Myr) in that area” [22] (p. 137). Archidiskodon Pohlig, 1888 [26], is a genus to which early European Mammuthus have long been referred, although it is seldom adopted as valid today [27]. Basically, the important point here is that while Lindsay et al. [22] stressed the correlation of the faunal datum with the Gauss-Matuyama reversal, there was also room for an earlier chronology.
Azzaroli [28] summarized the available data on—and popularized— the major mammal dispersal events that occurred during the Quaternary of Europe, including the “Elephant-Equus event”. Since then, the term (sometimes also referred to as the Equus-Elephant event, Equus/Elephant turnover, Mammuthus-Equus event, or similar expressions) has widely been used in the literature (e.g., [8][12][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]). It is worth noting that Lindsay et al. [22] and Azzaroli [28] used the term “dispersal events” to refer to short periods of intercontinental dispersals and faunal replacement (basically following the concept elaborated by Repenning [46][47]), epitomized by, but not limited to the taxa after which each event was named. Moreover, these dispersal events were also directly associated and thus intrinsically linked (in their interpretation at least) to salient climatic and environmental changes [29]. In other terms, the Elephant-Equus event was envisioned as a period of marked faunal renewal, witnessing the disappearance of a “warm forest assemblage” and the arrival of species of a “more open, parkland or savannah landscape”, most notably, primitive elephantid and monodactyl equid [28] (p. 118). Azzaroli [28] suggested a possible chronological range for the Elephant-Equus event between 3.0 and 2.5 Ma, but later Azzaroli et al. [29] favored approximating it at 2.6–2.5 Ma.
In the years following the introduction of the term in the literature, that is, between the 1990s and the early 2000s, further discoveries and reinterpretations of old collections have engendered doubts on the correlation of the Elephant-Equus event with the Gauss-Matuyama reversal, and on its synchronicity across Eurasia [48][49][50][51]. On the other hand, growing evidence was piling up testifying to abiotic [3][4][5][7] and the possibly related biotic changes in the environment (e.g., [52][53]). Eventually, in 2009, the Quaternary Period/System was formally ratified, and the base of the Pleistocene Epoch/Series was revised, officially resolving a long-lasting debate [54][55][56]. The agreed Pliocene-Pleistocene boundary, corresponding to the beginning of the Quaternary, was set in correspondence to MIS 103 and the Gauss-Matuyama boundary, hence at ~2.6 Ma. Indirectly, this provision enhanced the importance of the Elephant-Equus event, owing to its correlation with the beginning of the Quaternary.
Basically, despite representing an important biochronological concept evoked numerous times, the Elephant-Equus event has been, and it is still, invested by different meanings, spanning from it being used in a chronostratigraphic sense for denoting the beginning of the Quaternary [37][57], to considering it “a misleading term depicting a diachronous biochronogical event” [45] (p. 23).

This entry is adapted from the peer-reviewed paper 10.3390/quat6010016

References

  1. Channell, J.E.; Singer, B.S.; Jicha, B.R. Timing of Quaternary geomagnetic reversals and excursions in volcanic and sedimentary archives. Quat. Sci. Rev. 2020, 228, 106114.
  2. Gibbard, P.L.; Head, M.J. The Quaternary Period. In Geologic Time Scale 2020; Gradstein, F.M., Ogg, J.G., Schmitz, M.D., Ogg, G.M., Eds.; Elsevier: Amsterdam, The Netherlands, 2020; pp. 1217–1255.
  3. Shackleton, N.J. New data on the evolution of Pliocene climatic variability. In Paleoclimate and Evolution, with Emphasis on Human Evolution; Vrba, E.S., Denton, G.H., Patridge, T.C., Burckle, L.H., Eds.; Yale University Press: London, UK, 1995; pp. 242–248.
  4. Flesche Kleiven, H.; Jansen, E.; Fronval, T.; Smith, T.M. Intensification of Northern Hemisphere glaciations in the circum Atlantic region (3.5–2.4 Ma)—Ice-Rafted detritus evidence. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2002, 184, 213–223.
  5. Gibbard, P.L.; Smith, A.G.; Zalasiewicz, J.A.; Barry, T.L.; Cantrill, D.; Coe, A.L.; Cope, J.C.W.; Gale, A.S.; Gregory, F.J.; Powell, J.H.; et al. What status for the Quaternary? Boreas 2005, 34, 1–6.
  6. Zachos, J.; Pagani, M.; Sloan, L.; Thomas, E.; Billups, K. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 2001, 292, 686–693.
  7. Lisiecki, L.E.; Raymo, M.E. A Pliocene-Pleistocene stack of 57 globally distributed benthic d18O records. Paleoceanography 2005, 20, PA1003.
  8. Kahlke, R.-D.; García, N.; Kostopoulos, D.S.; Lacombat, F.; Lister, A.M.; Mazza, P.P.A.; Spassov, N.; Titov, V.V. Western Palaearctic palaeoenvironmental conditions during the Early and early Middle Pleistocene inferred from large mammal communities, and implications for hominin dispersal in Europe. Quat. Sci. Rev. 2011, 30, 1368–1395.
  9. Azzaroli, A. Villafranchian correlations based on large mammals. G. Geol. 1970, 35, 111–131.
  10. Azzaroli, A. The Villafranchian Stage in Italy and the Plio–Pleistocene boundary. G. Geol. 1977, 41, 61–79.
  11. Gliozzi, E.; Abbazzi, L.; Argenti, P.; Azzaroli, A.; Caloi, L.; Capasso Barbato, L.; Di Stefano, G.; Esu, D.; Ficcarelli, G.; Girotti, O.; et al. Biochronology of selected mammals, molluscs and ostracods from the middle Pliocene to the late Pleistocene in Italy. The state of the art. Riv. Ital. Paleontol. Stratigr. 1997, 103, 369–388.
  12. Rook, L.; Martínez-Navarro, B. Villafranchian: The long story of a Plio-Pleistocene European large mammal biochronologic unit. Quat. Int. 2010, 219, 134–144.
  13. Tedford, R.H. Principles and practices of mammalian geochronology in North America. In Proceedings of the North American Paleontological Convention; American Paleontology Convection Chicago; Allen Press: Lawrence, KS, USA, 1969; pp. 666–703.
  14. Mein, P. Résultats du groupe de travail des vertébrés: Bizonation du Néogène méditerranéen a partir des Mammifères. Rep. Act. RCMNS Work. Groups 1975, 78–81.
  15. Berggren, W.A.; Van Couvering, J.A. Biochronology. Am. Assoc. Petrol. Geol. Bull. 1978, 50, 1487–1500.
  16. Lindsay, E.H. European Late Cenozoic biochronology and the magnetic polarity time scale. Natl. Geogr. Soc. Res. Rep. 1985, 449–456.
  17. Azzaroli, A. Rinoceronti Pliocenici del Valdarno Inferiore. Palaeontogr. Ital. 1962, 57, 11–20.
  18. Heintz, E. Principaux résultats systématiques et biostratigraphiques de l’étude des Cervidés villafranchiens de France et d’Espagne. C. R. Acad. Sci. Paris 1968, 266, 2184–2186.
  19. Heintz, E. Les cervidés Villafranchiens de France et d’Espagne. Mem. Mus. Natl. Hist. Nat. Paris C 1970, 22, 1–206.
  20. Azzaroli, A.; Vialli, V. Villafranchian. G. Geol. 1971, 37, 221–232.
  21. Heintz, E.; Guérin, C.; Martin, R.; Prat, F. Principaux gisements villafranchiens de France: Listes fauniques et biostratigraphie. Mem. Bur. Rech. Geol. Miner. 1974, 78, 131–135.
  22. Lindsay, E.H.; Opdyke, N.D.; Johnson, N.M. Pliocene dispersal of the horse Equus and late Cenozoic mammalian dispersal events. Nature 1980, 287, 135–138.
  23. Linnaeus, C. Systema Naturae Per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, Cum Characteribus, Differentiis, Synonymis, Locis; Tomus, I., Editio Decima, R., Eds.; Laurentius Salvius: Stockholm, Sweden, 1758.
  24. Brookes, J. A Catalogue of the Anatomical & Zoological Museum of Joshua Brookes; Part 1.; R. Taylor: London, UK, 1828.
  25. Kochegura, V.V.; Zubakov, V.A. Palaeomagnetic time scale of the Ponto-Caspian Plio-Pleistocene deposits. Palaeogeogr. Palaeoclim. Palaeoecol. 1978, 23, 151–160.
  26. Pohlig, H. Dentition und Kranologie des Elephas antiquus Falc. mit Beiträgen über Elephas primigenius Blum. und Elephas meridionalis Nesti. Nova Acta Acad. Caesareae Leopold. -Carol. Ger. Nat. Curiosorum 1888, 53, 1–279.
  27. Maschenko, E.N.; Schvyreva, A.K.; Kalmykov, N.P. The second complete skeleton of Archidiskodon meridionalis (Elephantidae, Proboscidea) from the Stavropol Region, Russia. Quat. Sci. Rev. 2011, 30, 2273–2288.
  28. Azzaroli, A. Quaternary mammals and the end-Villafranchian dispersal event—A turning point in the history of Eurasia. Palaeogeogr. Palaeoclimatol. Palaeoecol. 1983, 44, 117–139.
  29. Azzaroli, A.; De Giuli, C.; Ficcarelli, G.; Torre, D. Late Pliocene to early mid-Pleistocene mammals in Eurasia: Faunal succession and dispersal events. Palaeogeogr. Palaeoclimatol. Palaeoecol. 1988, 66, 77–100.
  30. Turner, A. Large carnivores and earliest European hominids: Changing determinants of resource availability during the Lower and Middle Pleistocene. J. Hum. Evol. 1992, 22, 109–126.
  31. Rustioni, M.; Mazza, P. The genus Ursus in Eurasia: Dispersal events and stratigraphical significance. Riv. Ital Paleontol. Stratigr. 1993, 98, 487–494.
  32. Azzaroli, A. The “Elephant-Equus” and the “End-Villafranchian” events in Eurasia. In Paleoclimate and Evolution, with Emphasis on Human Evolution; Vrba, E.S., Denton, G.H., Patridge, T.C., Burckle, L.H., Eds.; Yale University Press: London, UK, 1995; pp. 311–318.
  33. Rio, D.; Sprovieri, R.; Castradori, D.; Di Stefano, E. The Gelasian Stage (Upper Pliocene): A new unit of the global standard chronostratigraphic scale. Episodes 1998, 21, 82–87.
  34. Azanza, B.; Alberdi, M.T.; Prado, J.L. Large mammal turnover pulses correlated with latest Neogene glacial trends in the northwestern Mediterranean region. Geol. Soc. Lond. (Special Publications) 2000, 181, 161–170.
  35. Fernández, M.H.; Vrba, E.S. A complete estimate of the phylogenetic relationships in Ruminantia: A dated species-level supertree of the extant ruminants. Biol. Rev. 2005, 80, 269–302.
  36. Palombo, M.R.; Sardella, R. Biochronology versus biostratigraphy: A true dilemma or a false trouble? The example of the Plio-Pleistocene large mammalian faunas from the Italian peninsula. Quat. Int. 2007, 160, 30–42.
  37. Pradella, C.; Rook, L. Mesopithecus (Primates, Cercopithecoidea) from Villafranca d’Asti (Early villafranchian; NW Italy) and palaeoecological context of its extinction. Swiss J. Geosci. 2007, 100, 145–152.
  38. Croitor, R.; Brugal, J.P. Ecological and evolutionary dynamics of the carnivore community in Europe during the last 3 million years. Quat. Int. 2010, 212, 98–108.
  39. Madurell-Malapeira, J.; Ros-Montoya, S.; Espigares, M.P.; Alba, D.M.; Aurell-Garrido, J. Villafranchian large mammals from the Iberian Peninsula: Paleobiogeography, paleoecology and dispersal events. J. Iber. Geol. 2014, 40, 167–178.
  40. Nomade, S.; Pastre, J.F.; Guillou, H.; Faure, M.; Guérin, C.; Delson, E.; Voinchet, P.; Messager, E. 40Ar/39Ar constraints on some French landmark Late Pliocene to Early Pleistocene large mammalian paleofaunas: Paleoenvironmental and paleoecological implications. Quat. Geochronol. 2014, 21, 2–15.
  41. Boulbes, N.; Van Asperen, E.N. Biostratigraphy and palaeoecology of European Equus. Front. Ecol. Evol. 2019, 7, 301.
  42. Tong, H.W.; Zhang, B. New fossils of Eucladoceros boulei (Artiodactyla, Mammalia) from Early Pleistocene Nihewan Beds, China. Palaeoworld 2019, 28, 403–424.
  43. Gkeme, A.G.; Koufos, G.D.; Kostopoulos, D.S. Reconsidering the equids from the early Pleistocene fauna of Apollonia 1 (Mygdonia Basin, Greece). Quaternary 2021, 4, 12.
  44. Harzhauser, M.; Neubauer, T.A. A review of the land snail faunas of the European Cenozoic–composition, diversity and turnovers. Earth-Sci. Rev. 2021, 217, 103610.
  45. Jin, C.; Wang, Y.; Liu, J.; Ge, J.; Zhao, B.; Liu, J.; Zhang, H.; Shao, Q.; Gao, C.; Zhao, B.; et al. Late Cenozoic mammalian faunal evolution at the Jinyuan Cave site of Luotuo Hill, dalian, northeast China. Quat. Int. 2021, 577, 15–28.
  46. Repenning, C.A. Nearctic mammalian dispersal in late Cenozoic. In The Bering Land Bridge; Hopkins, D.M., Ed.; Stanford University Press: Palo Alto, CA, USA, 1967; pp. 208–311.
  47. Repenning, C.A. Faunal exchanges between Siberia and North America. Can. J. Anthropol. 1980, 1, 37–44.
  48. Radulescu, C.; Samson, P.M. Villafranchian s. s. faunas of Romania. Il Quaternario 1995, 8, 377–382.
  49. Radulescu, C.; Samson, P.M. Biochronology and evolution of the early Pliocene to the early Pleistocene mammalian faunas of Romania. Boll. Soc. Paleontol. Ital. 2001, 40, 285–291.
  50. Lister, A.M.; Sher, A.V.; van Essen, H.; Wei, G. The pattern and process of mammoth evolution in Eurasia. Quat. Int. 2005, 126–128, 49–64.
  51. Lacombat, F.; Abbazzi, L.; Ferretti, M.P.; Martinez-Navarro, B.; Moulle, P.E.; Palombo, M.R.; Rook, L.; Turner, A.; Valli, A.M.F. New data on the Early Villafranchian fauna from Vialette (Haute-Loire, France) based on the collection of the Crozatier Museum (Le Puy-en-Velay, Haute-Loire, France). Quat Int. 2008, 179, 64–71.
  52. Miller, K.G.; Kominz, M.A.; Browning, J.V.; Wright, J.D.; Mountain, G.S.; Katz, M.E.; Sugarman, P.J.; Cramer, B.S.; Christie-Blick, N.; Pekar, S.F. The Phanerozoic Record of Global Sea-Level Change. Science 2005, 310, 1293–1298.
  53. Suc, J.P.; Popescu, S.M. Pollen records and climatic cycles in the North Mediterranean region since 2.7 Ma. Geol. Soc. Lond. (Special Publications) 2005, 247, 147–158.
  54. Gibbard, P.L.; Head, M.J. The newly-ratified definition of the Quaternary System/Period and redefinition of the Pleistocene Series/Epoch, and comparison of proposals advanced prior to formal ratification. Episodes 2010, 33, 152158.
  55. Gibbard, P.L.; Head, M.J.; Walker, M.; Subcommission on Quaternary Stratigraphy. Formal ratification of the Quaternary System/Period and the Pleistocene Series/Epoch with a base at 2.58 Ma. J. Quat. Sci. 2010, 25, 96102.
  56. Head, M.J.; Gibbard, P.L. Formal subdivision of the Quaternary System/Period: Past, present, and future. Quat. Int. 2015, 383, 4–35.
  57. Silva, P.G.; Bardají, T.; Baena Preysler, J.; Giner-Robles, J.L.; Van der Made, J.; Zazo, C.; Rosas, A.; Lario, J. Tabla cronoestratigráfica del Cuaternario de la península ibérica (v 3.0): Nuevos datos estratigráficos, paleontológicos y arqueológicos. Cuaternario y Geomorfología 2021, 35, 121–146.
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