CFEE JOINT SEMINAR: Evolution of semiaquatic hippopotamoids postcranial skeleton


Evolution: an international research seminar in Eastern Africa.
Paleobiodiversity, paleobiology, prehistory, paleoenvironments


11ème séance / 11th session: Evolution of semiaquatic hippopotamoids postcranial skeleton during the Cenozoic, par/by Florian Martin (University of Poitiers).

Mercredi 12 avril 2017 (15h30h-17h00) / Wenesday 12th April 2017 (3:30 PM-5:00 PM). Lieu / Venue: Auditorium of the Authority for Research and Conservation of Cultural Heritage

Organisation: CFEE & Authority for Research and Conservation of the Cultural Heritage (Heritage Collection & Laboratory Service Directorate, Heritage Training Unit).

Evolution of semiaquatic hippopotamoids postcranial skeleton during the Cenozoic

par/by Florian Martin

The Hippopotamoidea (Hippopotamidae and “anthracotheres”, sensu Gentry and Hooker1) are a mammalian super family having a wide distribution: they are known from Africa, Asia, Europe, northern and central America, and their temporal extension ranges from the Eocene to the present day. Today, this clade is only represented by two hippopotamid species belonging to two distinct genus: Hippopotamus amphibius and Choeropsis liberiensis2,3. Extant hippopotamids are the only remaining representatives of the Large Semiaquatic Herbivores (LSH), a mammalian guild that was much more abundant during the Cenozoic than it is today.

Hippopotamoids postcranial fossil remains, although abundant in museum collections, have received little attention to date even though the axial and the appendicular skeleton allows characterizing the locomotion of extinct taxa and thus offers insights into their habitats. Based on a broad comparative sample, including extant and extinct cetaceans (whales, dolphins, and porpoises), ruminants (cows, giraffes, deers, etc.), suoids (pigs and peccaries), and perissodactyls (horses, rhinos, tapirs), the locomotor constraints and abilities of extant and extinct hippopotamoids will be evaluated by mapping muscle and sinew insertions on bone reliefs4,5, by studying the shape of corresponding joint surfaces through three-dimensional geometric morphometric analyses6,7 and by focusing on bone internal microstructure observed by X-ray microtomography8. The goal of these methods is to investigate the evolution of the postcranial skeleton of semiaquatic hippopotamoids and of their inferred locomotor modes, and to put these in perspective of the Cenozoic increased aridity that caused wet land rarefaction and fragmentation.

Molecular phylogenetic studies have shown a close relationship between artiodactyls and cetaceans9,10, leading to the creation of the clade Cetartiodactyla Montgelard, Catzeflis & Douzery, 19979. Initially refuted by anatomists, this close relationship has found support with the description of ankle bones belonging to early cetaceans from Pakistan11,12. Among Cetartiodactyla, the Hippopotamoidea have been placed as the sister group of cetaceans leading to the creation of the clade Cetancodonta Arnason, Gullberg & Janke, 200413. This clade has been shown to be close to Ruminantia10. Nonetheless, there are still debates about the stem-group of hippopotamids filling the fossil record gap between the earliest hippopotamids14 and their common ancestor shared with Cetacea15. While some authors consider that the stem group of Hippopotamidae are the paleochoeres16,17, other studies agree on a close relationship with anthracotheres1,14,18–22. This is why it is important to bring additional phylogenetic characters in order to untangle these phylogenetic links. Moreover, most anatomical studies have relied on craniodental characters but the postcranial skeleton has rarely beenconsidered. Our goal is to identify new postcranial features that carry phylogenetic information.

  1. Gentry, A. W. & Hooker, J. J., 1988, The phylogeny of the Artiodactyla, Phylogeny Classif. Tetrapods 2, 235-272.
  2. Eltringham, S. K., 1999, The Hippos: Natural History and Conservation, Princeton University Press.
  3. Boisserie, J.-R., 2005, The phylogeny and taxonomy of Hippopotamidae (Mammalia: Artiodactyla): a review based on morphology and cladistic analysis, Zool. J. Linn. Soc.143, 1-26.
  4. Fisher, R. E., Scott, K. M. & Naples, V. L., 2007, Forelimb myology of the pygmy hippopotamus (Choeropsis liberiensis), Anat. Rec. Adv. Integr. Anat. Evol. Biol. 290, 673-693.
  5. Fisher, R. E., Scott, K. M. & Adrian, B., 2010, Hind limb myology of the common hippopotamus, Hippopotamus amphibius (Artiodactyla: Hippopotamidae), Zool. J. Linn. Soc. 158, 661-682.
  6. Bookstein, F. L., 1991, Morphometric tools for landmark analysis: Geometry and biology, New York: Cambridge Univ Press.
  7. Gunz, P., Mitteroecker, P. & Bookstein, F. L. in Modern Morphometrics in Physical Anthropology (ed. Slice, D. E.) 73-98 (Springer US, 2005). doi:10.1007/0-387-27614-9_3
  8. Houssaye, A. et al., 2016, Biomechanical evolution of solid bones in large animals: a microanatomical investigation, Biol. J. Linn. Soc. 117, 350-371.
  9. Montgelard, C., Catzeflis, F. M. & Douzery, E., 1997, Phylogenetic relationships of artiodactyls and cetaceans as deduced from the comparison of cytochrome b and 12S rRNA mitochondrial sequences, Mol. Biol. Evol. 14, 550-559.
  10. Nikaido, M., Rooney, A. P. & Okada, N., 1999, Phylogenetic relationships among cetartiodactyls based on insertions of short and long interpersed elements: Hippopotamuses are the closest extant relatives of whales, Proc. Natl. Acad. Sci. 96, 10261-10266.
  11. Gingerich, P. D., Haq, M. ul, Zalmout, I. S., Khan, I. H. & Malkani, M. S., 2001, Origin of Whales from Early Artiodactyls: Hands and Feet of Eocene Protocetidae from Pakistan, Science 293, 2239-2242.
  12. Thewissen, J. G. M., Williams, E. M., Roe, L. J. & Hussain, S. T., 2001, Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls, Nature 413, 277-281.
  13. Arnason, U., Gullberg, A. & Janke, A., 2004, Mitogenomic analyses provide new insights into cetacean origin and evolution, Gene 333, 27-34.
  14. Orliac, M., Boisserie, J.-R., MacLatchy, L. & Lihoreau, F., 2010, Early Miocene hippopotamids (Cetartiodactyla) constrain the phylogenetic and spatiotemporal settings of hippopotamid origin, Proc. Natl. Acad. Sci. 107, 11871-11876.
  15. Thewissen, J. G. M. & Williams, E. M., 2002, The Early Radiations of Cetacea (Mammalia): Evolutionary Pattern and Developmental Correlations, Annu. Rev. Ecol. Syst. 33, 73-90.
  16. Pickford, M., 1983, On the origins of Hippopotamidae togetherwith descriptions of two new species, a new genus and a new subfamily from the Miocene of Kenya, Geobios 16, 193-217.
  17. Pickford, M., 2009, The myth of the hippo-like anthracothere: The eternal problem of homology and convergence, Rev. Esp. Paleontol. 23, 31-90.
  18. Boisserie, J.-R., Lihoreau, F. & Brunet, M., 2005, Origins of Hippopotamidae (Mammalia, Cetartiodactyla): towards resolution, Zool. Scr. 34, 119–143.
  19. Boisserie, J.-R., Lihoreau, F. & Brunet, M., 2005, The position of Hippopotamidae within Cetartiodactyla, Proc. Natl. Acad. Sci. U. S. A. 102, 1537-1541.
  20. O’Leary, M. A. & Gatesy, J., 2008, Impact of increased character sampling on the phylogeny of Cetartiodactyla (Mammalia): combined analysis including fossils, Cladistics 24, 397-442.
  21. Boisserie, J.-R. et al., 2010, Morphology and phylogenetic relationships of the earliest known hippopotamids (Cetartiodactyla, Hippopotamidae, Kenyapotaminae), Zool. J. Linn. Soc. 158, 325-366.
  22. Lihoreau, F., Boisserie, J.-R., Manthi, F. K. & Ducrocq, S., 2015, Hippos stem from the longest sequence of terrestrial cetartiodactyl evolution in Africa, Nat. Commun. 6.

L’intervenant / The speaker

Florian Martin est doctorant à l’Institut de paléoprimatologie, Paléontologie Humaine : Évolution et Paléoenvironnements (IPHEP), UMR  7262 CNRS & Université de Poitiers.
Florian Martin is PhD student at the Institute of Paleoprimatology,
Human paleontology: Evolution and Paleoenvironments (IPHEP), UMR 7262 CNRS & University of Poitiers.

Organisateurs du séminaire / Convenors of the seminar series: Behailu Habte (ARCCH), Jean-Renaud Boisserie (CNRS, CFEE) & Yonas Beyene (associate researcher at CFEE, ARCC-Hawassa).

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