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Home / Equine Research Bank / Sci Rep / Evolution of Old World Equus and origin of the zebra-ass cla...
Scientific reports2021; 11(1); 10156; doi: 10.1038/s41598-021-89440-9

Evolution of Old World Equus and origin of the zebra-ass clade.

Abstract: Evolution of the genus Equus has been a matter of long debate with a multitude of hypotheses. Currently, there is no consensus on either the taxonomic content nor phylogeny of Equus. Some hypotheses segregate Equus species into three genera, Plesippus, Allohippus and Equus. Also, the evolutionary role of European Pleistocene Equus stenonis in the origin of the zebra-ass clade has been debated. Studies based on skull, mandible and dental morphology suggest an evolutionary relationship between North American Pliocene E. simplicidens and European and African Pleistocene Equus. In this contribution, we assess the validity of the genera Plesippus, Allohippus and Equus by cladistic analysis combined with morphological and morphometrical comparison of cranial anatomy. Our cladistic analysis, based on cranial and postcranial elements (30 taxa, 129 characters), supports the monophyly of Equus, denies the recognition of Plesippus and Allohippus and supports the derivation of Equus grevyi and members of the zebra-ass clade from European stenonine horses. We define the following evolutionary steps directly relevant to the phylogeny of extant zebras and asses: E. simplicidens-E. stenonis-E. koobiforensis-E. grevyi -zebra-ass clade. The North American Pliocene species Equus simplicidens represents the ancestral stock of Old World Pleistocene Equus and the zebra-ass clade. Our phylogenetic results uphold the most recent genomic outputs which indicate an age of 4.0-4.5 Ma for the origin and monophyly of Equus.
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Publication Date: 2021-05-12 PubMed ID: 33980921PubMed Central: PMC8114910DOI: 10.1038/s41598-021-89440-9Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research investigates the historical evolution and origin of the Equus genus, including zebras and asses, challenging existing theories and proposing a new lineage based on cranial and postcranial anatomical analysis.

Background of Research

  • The research focuses on the evolution of the genus Equus, which has been a debatable topic with no set consensus on its taxonomic content or phylogeny.
  • Some prevalent hypotheses segregate the Equus species into three different genera: Plesippus, Allohippus, and Equus.
  • This study also explores the hypothesized evolutionary role of European Pleistocene Equus stenonis in the origin of the zebra-ass clade.
  • It is noted that previous studies based on skull, mandible, and dental morphology suggest a link between North American Pliocene E. simplicidens and Pleistocene Equus from Europe and Africa.

Research Methodology

  • This study evaluates the validity of the genera Plesippus, Allohippus, and Equus and the supposed connections between them using cladistic analysis combined with morphological and morphometric comparison of cranial anatomy.
  • The research carries out a cladistic analysis based on cranial and postcranial elements across 30 taxa and 129 characters.

Findings and Conclusion

  • The analysis supports the monophyly of Equus, denies the recognition of Plesippus and Allohippus, and supports the evolution of Equus grevyi and the zebra-ass clade from European stenonine horses.
  • The research outlines an evolutionary pathway for extant zebras and asses, starting with the North American Pliocene species Equus simplicidens, which the study suggests is the ancestral stock of Old World Pleistocene Equus and the zebra-ass clade.
  • Finally, the results uphold most recent genomic outputs indicating an age of 4.0 – 4.5 million years for the origin and monophyly of Equus.

Cite This Article

APA
Cirilli O, Pandolfi L, Rook L, Bernor RL. (2021). Evolution of Old World Equus and origin of the zebra-ass clade. Sci Rep, 11(1), 10156. https://doi.org/10.1038/s41598-021-89440-9

Publication

Scientific reports
ISSN: 2045-2322
NlmUniqueID: 101563288
Country: England
Language: English
Volume: 11
Issue: 1
Pages: 10156
PII: 10156

Researcher Affiliations

Cirilli, Omar
  • Dottorato Regionale Pegaso in Scienze della Terra, Università di Pisa, Via S. Maria 53, 56126, Pisa, Italy. omar.cirilli@phd.unipi.it.
  • Dipartimento di Scienze della Terra, Paleo[Fab]Lab, Università degli Studi di Firenze, Via G. La Pira 4, 50121, Firenze, Italy. omar.cirilli@phd.unipi.it.
Pandolfi, Luca
  • Dipartimento di Scienze della Terra, Paleo[Fab]Lab, Università degli Studi di Firenze, Via G. La Pira 4, 50121, Firenze, Italy. luca.pandolfi@unifi.it.
Rook, Lorenzo
  • Dipartimento di Scienze della Terra, Paleo[Fab]Lab, Università degli Studi di Firenze, Via G. La Pira 4, 50121, Firenze, Italy.
Bernor, Raymond L
  • Laboratory of Evolutionary Biology, Department of Anatomy, College of Medicine, 520 W St. N.W, Washington, DC, 20059, USA.
  • Department of Anthropology, Human Origins Program, Smithsonian Institution, Washington, DC, 20560, USA.

MeSH Terms

  • Animals
  • Biological Evolution
  • Bone and Bones / anatomy & histology
  • Equidae / anatomy & histology
  • Equidae / classification
  • Equidae / genetics
  • Evolution, Molecular
  • Genetic Variation
  • Genotype
  • Horses / anatomy & histology
  • Horses / classification
  • Horses / genetics
  • Phylogeny

Conflict of Interest Statement

The authors declare no competing interests.

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Citations

This article has been cited 2 times.
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  2. Cirilli O, Machado H, Arroyo-Cabrales J, Barrón-Ortiz CI, Davis E, Jass CN, Jukar AM, Landry Z, Marín-Leyva AH, Pandolfi L, Pushkina D, Rook L, Saarinen J, Scott E, Semprebon G, Strani F, Villavicencio NA, Kaya F, Bernor RL. Evolution of the Family Equidae, Subfamily Equinae, in North, Central and South America, Eurasia and Africa during the Plio-Pleistocene.. Biology (Basel) 2022 Aug 24;11(9).
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