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Foss. Rec., 20, 259-278, 2017
https://doi.org/10.5194/fr-20-259-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
07 Dec 2017
Koristocetus pescei gen. et sp. nov., a diminutive sperm whale (Cetacea: Odontoceti: Kogiidae) from the late Miocene of Peru
Alberto Collareta1,2, Olivier Lambert3, Christian de Muizon4, Mario Urbina5, and Giovanni Bianucci1 1Dipartimento di Scienze della Terra, Università di Pisa, via Santa Maria 53, 56126 Pisa, Italy
2Dottorato Regionale in Scienze della Terra Pegaso, Università di Pisa, via Santa Maria 53, 56126 Pisa, Italy
3Institut Royal des Sciences Naturelles de Belgique, D.O. Terre et Histoire de la Vie, rue Vautier 29, 1000 Brussels, Belgium
4Département Origines et Évolution, Muséum National d'Histoire Naturelle, Centre de Recherches sur la paléobiodiversité et les paléoenvironnements – CR2P (CNRS, MNHN, UPMC, Sorbonne Université), rue Buffon 8, 75005 Paris, France
5Departamento de Paleontologia de Vertebrados, Museo de Historia Natural de la Universidad Nacional Mayor de San Marcos, avenida Arenales 1256, Lima 14, Peru
Abstract. Among odontocetes, members of the family Kogiidae (pygmy and dwarf sperm whales) are known as small-sized and in many respects enigmatic relatives of the great sperm whale Physeter macrocephalus. Most of the still scanty fossil record of Kogiidae is represented by isolated skulls and ear bones from Neogene deposits of the Northern Hemisphere, with the significant exception of Scaphokogia, a highly autapomorphic genus from late Miocene deposits of the Pisco Formation exposed along the southern coast of Peru. Here we report on a new fossil kogiid from Aguada de Lomas, a site where the late Miocene beds of the Pisco Formation are exposed. This specimen consists of an almost complete cranium representing a new taxon of Kogiidae: Koristocetus pescei gen. et sp. nov. Koristocetus mainly differs from extant Kogia spp. by displaying a larger temporal fossa and well-individualized dental alveoli on the upper jaws. Coupled with a relatively elongated rostrum, these characters suggest that Koristocetus retained some degree of raptorial feeding abilities, contrasting with the strong suction feeding specialization seen in Recent kogiids. Our phylogenetic analysis recognizes Koristocetus as the earliest branching member of the subfamily Kogiinae. Interestingly, Koristocetus shared the southern coast of present-day Peru with members of the genus Scaphokogia, whose unique convex rostrum and unusual neurocranial morphology seemingly indicate a peculiar foraging specialization that has still to be understood. In conclusion, Koristocetus evokes a long history of high diversity, morphological disparity, and sympatric habits in fossil kogiids, thus suggesting that our comprehension of the evolutionary history of pygmy and dwarf sperm whales is still far from being exhaustive.

Citation: Collareta, A., Lambert, O., de Muizon, C., Urbina, M., and Bianucci, G.: Koristocetus pescei gen. et sp. nov., a diminutive sperm whale (Cetacea: Odontoceti: Kogiidae) from the late Miocene of Peru, Foss. Rec., 20, 259-278, https://doi.org/10.5194/fr-20-259-2017, 2017.
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Short summary
Extant pygmy and dwarf sperm whales (Kogia spp.) are known as small-sized and enigmatic relatives of the great sperm whale Physeter. Here we describe Koristocetus pescei, a new fossil kogiid from the late Miocene (ca 7 million years ago) of Peru. The description of this new form evokes a long history of morphological and ecological diversity in fossil kogiids, thus suggesting that our comprehension of the evolutionary history of diminutive sperm whales is still far from being exhaustive.
Extant pygmy and dwarf sperm whales (Kogia spp.) are known as small-sized and enigmatic...
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