FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / PLoS One / Occlusal enamel complexity in middle miocene to holocene equ...
PloS one2014; 9(2); e90184; doi: 10.1371/journal.pone.0090184

Occlusal enamel complexity in middle miocene to holocene equids (Equidae: Perissodactyla) of North America.

Abstract: Four groups of equids, "Anchitheriinae," Merychippine-grade Equinae, Hipparionini, and Equini, coexisted in the middle Miocene, but only the Equini remains after 16 Myr of evolution and extinction. Each group is distinct in its occlusal enamel pattern. These patterns have been compared qualitatively but rarely quantitatively. The processes influencing the evolution of these occlusal patterns have not been thoroughly investigated with respect to phylogeny, tooth position, and climate through geologic time. We investigated Occlusal Enamel Index, a quantitative method for the analysis of the complexity of occlusal patterns. We used analyses of variance and an analysis of co-variance to test whether equid teeth increase resistive cutting area for food processing during mastication, as expressed in occlusal enamel complexity, in response to increased abrasion in their diet. Results suggest that occlusal enamel complexity was influenced by climate, phylogeny, and tooth position through time. Occlusal enamel complexity in middle Miocene to Modern horses increased as the animals experienced increased tooth abrasion and a cooling climate.
Get Full Text
Publication Date: 2014-02-27 PubMed ID: 24587267PubMed Central: PMC3937353DOI: 10.1371/journal.pone.0090184Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article
  • Research Support
  • Non-U.S. Gov't

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.

The research investigates how the complexity of tooth enamel in several groups of equids from North America changed over the course of the middle Miocene to the modern period. Specifically, it analyzes if the changes in their diet and climatic conditions influenced the occlusal enamel complexity in these animals.

Research Focus and Methodology

  • The research was focused on four distinct groups of equids (a family that includes horses and related animals) that coexisted in the middle Miocene period. These include: Anchitheriinae, Merychippine-grade Equinae, Hipparionini, and Equini.
  • These animal groups each have unique patterns on the biting surfaces of their teeth, known as occlusal enamel patterns. How these patterns developed and evolved over the years was the key focus of this study.
  • The study involved a quantitative method called Occlusal Enamel Index to assess the complexity of the occlusal enamel patterns.
  • Analyses of variance and analyses of covariance were also conducted to test whether these equids’ teeth increased their resistive cutting area (which would be necessary for food processing during chewing) in response to their diets becoming more abrasive.

Results and Conclusions

  • Results from this research indicated that the complexity of the occlusal enamel patterns was influenced by several factors: the species’ phylogeny, which describes how they are related to their ancestors; the position of the teeth in the mouth; and the climatic conditions of the era.
  • In response to a diet that caused more tooth abrasion (wear and tear), and a climate that was becoming cooler, the occlusal enamel complexity in these equid species increased from the middle Miocene period to the modern era.
  • This suggests that over time, equids have adapted their teeth to be more effective at processing food, as their diets and environments have changed.

Implications of the Study

  • The study provides a better understanding of how environmental factors including diet and climate can influence the evolution of biological traits in species.
  • It also helps to explain how members of the equid family have survived and persisted through geological time, despite significant changes in their environments.
  • Furthermore, such research provides insights into the broader processes of evolution and adaptation in the context of changing climates and habitats.

Cite This Article

APA
Famoso NA, Davis EB. (2014). Occlusal enamel complexity in middle miocene to holocene equids (Equidae: Perissodactyla) of North America. PLoS One, 9(2), e90184. https://doi.org/10.1371/journal.pone.0090184

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 9
Issue: 2
Pages: e90184
PII: e90184

Researcher Affiliations

Famoso, Nicholas A
  • Department of Geological Sciences and Museum of Natural and Cultural History, University of Oregon, Eugene, Oregon, United States of America.
Davis, Edward Byrd
  • Department of Geological Sciences and Museum of Natural and Cultural History, University of Oregon, Eugene, Oregon, United States of America.

MeSH Terms

  • Analysis of Variance
  • Animals
  • Biological Evolution
  • Dental Enamel
  • Dental Occlusion
  • Equidae / classification
  • Equidae / genetics
  • North America
  • Phylogeny
  • Tooth / anatomy & histology

Conflict of Interest Statement

The authors have declared that no competing interests exist.

References

This article includes 60 references
  1. Osborn HF. Equidae of the Oligocene, Miocene, and Pliocene of North America, iconographic type revision. Memoirs of the American Museum of Natural History 2: 1–217.
  2. Simpson GG. Horses: the horse family in the modern world and through sixty million years of history. New York, Oxford University Press.
  3. Franzen JL. The rise of horses: 55 million years of evolution. The Johns Hopkins University Press, Baltimore.
  4. Quinn JH. Miocene Equidae of the Texas Gulf Coastal Plain. University of Texas Publication 5516: 1–102.
  5. MacFadden BJ. Equidae. In: Janis CM, Scott KM, Jacobs LL (Eds.), Evolution of Tertiary Mammals of North America, v.1: Cambridge University Press, New York, 537–559.
  6. Famoso NA, Pagnac D. A comparison of the Clarendonian Equid assemblages from the Mission Pit, South Dakota and Ashfall Fossil Beds, Nebraska. Transactions of the Nebraska Academy of Sciences 32: 98–107.
  7. Famoso NA, Feranec RS, Davis EB. Occlusal enamel complexity and its implications for lophodonty, hypsodonty, body mass and diet in extinct and extant ungulates. Palaeogeogr Palaeoclimatol Palaeoecol 387: 211–216.
    doi: 10.1016/j.palaeo.2013.07.006google scholar: lookup
  8. Strömberg CAE. Evolution of hypsodonty in Equids: testing a hypothesis of adaptation. Paleobiology 32: 236–258.
  9. Jardine PE, Janis CM, Sahney S, Benton MJ. Grit not grass: Concordant patterns of early origin of hypsodonty in Great Plains ungulates and Glires. Palaeogeogr Palaeoclimatol Palaeoecol 365–366: 1–10.
    doi: 10.1016/j.palaeo.2012.09.001google scholar: lookup
  10. Lucas PW, Omar R, Al-Fadhalah K, Almusallam AS, Henry AG, Michael S, Thai LA, Watzke J, Strait DS, Atkins AG. Mechanisms and causes of wear in tooth enamel: implications for hominin diets.. J R Soc Interface 2013 Mar 6;10(80):20120923.
    doi: 10.1098/rsif.2012.0923pmc: PMC3565742pubmed: 23303220google scholar: lookup
  11. Sanson GD, Kerr SA, Gross KA. Do silica phytoliths really wear mammalian teeth?. J Archaeol Sci 34: 526–531.
    doi: 10.1016/j.jas.2006.06.009google scholar: lookup
  12. Damuth J, Janis CM. On the relationship between hypsodonty and feeding ecology in ungulate mammals, and its utility in palaeoecology.. Biol Rev Camb Philos Soc 2011 Aug;86(3):733-58.
    pubmed: 21418504doi: 10.1111/j.1469-185x.2011.00176.xgoogle scholar: lookup
  13. Pfretzschner HU. Enamel microstructure in the phylogeny of the Equidae. Journal of Vertebrate Paleontology 13: 342–349.
  14. Forsten A. Fossil horses of the Texas Gulf Coastal Plain: A revision. Pierce-Sellards Series, Texas Memorial Museum 22: 1–86.
  15. MacFadden BJ. Systematics and phylogeny of Hipparion, Neohipparion, Nannippus, and Cormohipparion (Mammalia, Equidae) from the Miocene and Pliocene of the New World. Bull. Am. Mus. Nat. Hist. 179: 1–195.
  16. MacFadden BJ. Fossil horses from “Eohippus” (Hyracotherium) to Equus; 2. Rates of dental evolution revisited. Biol J Linn Soc Lond 35: 37–48.
  17. Hulbert RC. Calippus and Protohippus (Mammalia, Perissodactyla, Equidae) from the Miocene (Barstovian-Early Hemphillian) of the gulf coastal plain. Florida Museum of Natural History 32: 221–340.
  18. Hulbert RC. Cormohipparion and Hipparion (Mammalia, Perissodactyla, Equidae) from the late Neogene of Florida. Florida Museum of Natural History 33: 229–338.
  19. Ungar PS. Mammal teeth: origin, evolution, and diversity. The Johns Hopkins University Press, Baltimore.
  20. Rensberger JM, Forsten A, Fortelius M. Functional evolution of the cheek tooth pattern and chewing direction in Tertiary horses. Paleobiology 10: 439–452.
  21. Heywood JJN. Functional anatomy of bovid upper molar occlusal surfaces with respect to diet. J Zool 281: 1–11.
  22. Kaiser TM, Fickel J, Streich WJ, Hummel J, Clauss M. Enamel ridge alignment in upper molars of ruminants in relation to their diet. J Zool 81: 12–25.
  23. Felsenstein J. Phylogenies and the comparative method. Am Nat 125(1): 1–15.
  24. MacFadden BJ. Fossil horses: systematics, paleobiology, and evolution of the family Equidae. Cambridge University Press, New York.
  25. Macfadden BJ. Evolution. Fossil horses--evidence for evolution.. Science 2005 Mar 18;307(5716):1728-30.
    pubmed: 15774746doi: 10.1126/science.1105458google scholar: lookup
  26. MacFadden BJ, Hulbert RC. Explosive speciation at the base of the adaptive radiation of Miocene grazing horses. Nature 33(1): 466–468.
  27. Hulbert RC, MacFadden BJ. Morphological transformation and cladogenesis at the base of the adaptive radiation of Miocene hypsodont horses. Am. Mus. Novit. 3000: 1–61.
  28. Prado JL, Alberdi MT. A cladistics analysis of the horses of the Tribe Equini. Palaeontology 39: 663–680.
  29. Martins EP, Diniz-Filho JA, Housworth EA. Adaptive constraints and the phylogenetic comparative method: a computer simulation test.. Evolution 2002 Jan;56(1):1-13.
    pubmed: 11913655
  30. Rohlf FJ. A comment on phylogenetic correction.. Evolution 2006 Jul;60(7):1509-15.
    pubmed: 16929667doi: 10.1554/05-550.1google scholar: lookup
  31. Hansen TF, Pienaar J, Orzack SH. A comparative method for studying adaptation to a randomly evolving environment.. Evolution 2008 Aug;62(8):1965-77.
    pubmed: 18452574doi: 10.1111/j.1558-5646.2008.00412.xgoogle scholar: lookup
  32. Stack JC, Harmon LJ, O’Meara B. RBrownie: an R package for testing hypotheses about rates of evolutionary change. Methods Ecol Evol 2: 660–662.
  33. Cayuela L, Granzow-de la Cerda Í, Albuquerque FS, Golicher DJ. Taxonstand: An r package for species names standardization in vegetation databases. Methods Ecol Evol 3: 1078–1083.
  34. Slater GJ, Harman LJ. Unifying fossils and phylogenies for comparative analyses of diversification and trait evolution. Methods Ecol Evol 4(8): 699–702.
  35. Mihlbachler MC, Rivals F, Solounias N, Semprebon GM. Dietary change and evolution of horses in North America.. Science 2011 Mar 4;331(6021):1178-81.
    pubmed: 21385712doi: 10.1126/science.1196166google scholar: lookup
  36. Becerra F, Vassallo AI, Echeverría AI, Casinos A. Scaling and adaptations of incisors and cheek teeth in caviomorph rodents (Rodentia, Hystricognathi).. J Morphol 2012 Oct;273(10):1150-62.
    pubmed: 22730038doi: 10.1002/jmor.20051google scholar: lookup
  37. Skinner MF, MacFadden BJ. Cormohipparion n. gen. (Mammalia, Equidae) from the North American Miocene (Barstovian-Clarendonian). J Paleontol 51: 912–926.
  38. Shapiro SS, Wilk MB. An analysis of variance test for normality (complete samples). Biometrika 52: 591–611.
  39. Bartlett MS. Properties of sufficiency and statistical tests. Proc R Soc Lond A 160: 268–282.
  40. Zar JH. Biostatistical analysis, 5th Edition. Pearson Prentice-Hall, Upper Saddle River.
  41. Wilcoxon F. Individual Comparisons by Ranking Methods. Biometrics 1: 80–83.
  42. Kramer CY. Extension of multiple range tests to group means with unequal numbers of replications. Biometrics 12: 307–310.
  43. Stirton RA. Phylogeny of North American Equidae. University of California Publications, Bulletin of the Department of Geological Sciences 25: 165–198.
  44. MacDonald JR, MacDonald ML, Toohey LM. The species, genera, and tribes of the living and extinct horses of the world 1758–1966. Dakoterra 4: 1–429.
  45. Kelly TS. New Miocene Horses from the Caliente Formation, Cuyama Valley Badlands, California. Contributions in Science 445: 1–33.
  46. Pagnac D. Scaphohippus, a new genus of horse (Mammalia: Equidae) from the Barstow Formation of California. J. Mammal. Evol. 13: 37–61.
  47. Azzaroli A, Voorhies MR. The genus Equus in North America. The Blancan species. Palaeontographia Italica 80: 175–198.
  48. Weinstock J, Willerslev E, Sher A, Tong W, Ho SY, Rubenstein D, Storer J, Burns J, Martin L, Bravi C, Prieto A, Froese D, Scott E, Xulong L, Cooper A. Evolution, systematics, and phylogeography of pleistocene horses in the new world: a molecular perspective.. PLoS Biol 2005 Aug;3(8):e241.
    pmc: PMC1159165pubmed: 15974804doi: 10.1371/journal.pbio.0030241google scholar: lookup
  49. Whistler DP. Geologic history of the El Paso Mountains region. San Bernardino County Museum Association Quarterly 38(3): 108–113.
  50. Hulbert RC, Whitmore FC. Late Miocene mammals from the Mauvilla Local Fauna, Alabama. Florida Museum of Natural History 46(1): 1–28.
  51. Eisenmann V, Alberdi MT, DeGiuli C, Staesche U. Methodology. in: Woodburne MO, Sondarr P (Eds.), Studying fossil horses, 1–71.
  52. Woodburne MO. Phyletic diversification of the Cormohipparion occidentale complex (Mammalia, Perissodactyla, Equidae), late Miocene, North America, and the origin of the Old World Hippotherium datum. Bull. Am. Mus. Nat. Hist. 306: 3–138.
  53. Zachos JC, Dickens GR, Zeebe RE. An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics.. Nature 2008 Jan 17;451(7176):279-83.
    pubmed: 18202643doi: 10.1038/nature06588google scholar: lookup
  54. Price EO. Behavioral development in animals undergoing domestication. Appl. Anim. Behav. Sci. 65(3): 245–271.
  55. O’Regan HJ, Kitchener AC. The effects of captivity on the morphology of captive, domesticated and feral mammals. Mamm Rev 35: 215–230.
    doi: 10.1111/j.1365-2907.2005.00070.xgoogle scholar: lookup
  56. Renaud S, Auffray JC. Adaptation and plasticity in insular evolution of the house mouse mandible. J Zool Syst Evol Res 48: 138–150.
    doi: 10.1111/j.14390469.2009.00527.xgoogle scholar: lookup
  57. Roth VL. Fabricational noise in elephant dentitions. Paleobiology 15: 165–179.
  58. Roth VL. Quantitative variation in elephant dentitions: Implications for the delimitation of fossil species. Paleobiology 18: 184–202.
  59. Carrasco MA, Kraatz BP, Davis EB, Barnosky AD. Miocene Mammal Mapping Project (MIOMAP). University of California Museum of Paleontology .
  60. Roy T, Bopp L, Gehlen M, Schneider B, Cadule P. Regional Impacts of Climate Change and Atmospheric CO2 on Future Ocean Carbon Uptake: A Multimodel Linear Feedback Analysis. J Clim 24: 2300–2318.
    doi: 10.1175/2010JCLI3787.1google scholar: lookup

Citations

This article has been cited 2 times.
  1. Famoso NA, Davis EB. On the relationship between enamel band complexity and occlusal surface area in Equids (Mammalia, Perissodactyla).. PeerJ 2016;4:e2181.
    doi: 10.7717/peerj.2181pubmed: 27441119google scholar: lookup
  2. Winkler DE, Kaiser TM. Structural Morphology of Molars in Large Mammalian Herbivores: Enamel Content Varies between Tooth Positions.. PLoS One 2015;10(8):e0135716.
    doi: 10.1371/journal.pone.0135716pubmed: 26313359google scholar: lookup
Subscribe to our newsletter
Join 99,359 horse owners like you who receive our email updates on horse health and nutrition.