Earliest Mysticete from the Late Eocene of Peru Sheds New Light on the Origin of Baleen Whales

Olivier Lambert, Manuel Martínez-Cáceres, Giovanni Bianucci, Claudio Di Celma, Rodolfo Salas-Gismondi, Etienne Steurbaut, Mario Urbina, Christian de Muizon

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35 Scopus citations

Abstract

Although combined molecular and morphological analyses point to a late middle Eocene (38–39 million years ago) origin for the clade Neoceti (Odontoceti, echolocating toothed whales plus Mysticeti, baleen whales, and relatives), the oldest known mysticete fossil dates from the latest Eocene (about 34 million years ago) of Antarctica [1, 2]. Considering that the latter is not the most stemward mysticete in recent phylogenies and that Oligocene toothed mysticetes display a broad morphological disparity most likely corresponding to contrasted ecological niches, the origin of mysticetes from a basilosaurid ancestor and its drivers are currently poorly understood [1, 3–8]. Based on an articulated cetacean skeleton from the early late Eocene (Priabonian, around 36.4 million years ago) of the Pisco Basin, Peru, we describe a new archaic tooth-bearing mysticete, Mystacodon selenensis gen. et sp. nov. Being the geologically oldest neocete (crown group cetacean) and the earliest mysticete to branch off described so far, the new taxon is interpreted as morphologically intermediate between basilosaurids and later toothed mysticetes, providing thus crucial information about the anatomy of the skull, forelimb, and innominate at these critical initial stages of mysticete evolution. Major changes in the morphology of the oral apparatus (including tooth wear) and flipper compared to basilosaurids suggest that suction and possibly benthic feeding represented key, early ecological traits accompanying the emergence of modern filter-feeding baleen whales’ ancestors.
Original languageAmerican English
Pages (from-to)1535-1541.e2
Number of pages0
JournalCurrent Biology
Volume27
Issue number10
DOIs
StatePublished - 22 May 2017

Keywords

  • baleen whale
  • cetacean
  • early Priabonian
  • late Eocene
  • Mysticeti
  • Peru
  • suction feeding
  • Yumaque Formation

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    Lambert, O., Martínez-Cáceres, M., Bianucci, G., Di Celma, C., Salas-Gismondi, R., Steurbaut, E., Urbina, M., & de Muizon, C. (2017). Earliest Mysticete from the Late Eocene of Peru Sheds New Light on the Origin of Baleen Whales. Current Biology, 27(10), 1535-1541.e2. https://doi.org/10.1016/j.cub.2017.04.026