The tempo of cetacean cranial evolution

• Published in: Current Biology
• Main Authors: Coombs, Ellen J., Felice, Ryan N., Clavel, Julien, Park, Travis, Bennion, Rebecca, Churchill, Morgan, Geisler, Jonathan H., Beatty, Brian, Goswami, Anjali
• Other Authors: Division of Biosciences, Department of Genetics, Evolution & Environment, University College of London London (UCL), Department of Life Sciences, Natural History Museum Geneva, Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Division of Biosciences, Cell & Developmental Biology, Équipe 6 - Paléontologie, Paléoécologie, Paléobiogéographie, Évolution (P3E), Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS), Evolution & Diversity Dynamics Lab, Université de Liège, OD Earth and History of Life, Royal Belgian Institute of Natural Sciences (RBINS), Department of Biology, University of Wisconsin Oshkosh (UWO)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: cranium; diversity; ecology cetaceans; evolutionary rates; morphology; [SDV.BA.ZV]Life Sciences [q-bio]/Animal biology/Vertebrate Zoology; [SDV.BID.EVO]Life Sciences [q-bio]/Biodiversity/Populations and Evolution [q-bio.PE]; baleen whales; toothed whales
• Online Access: https://hal.archives-ouvertes.fr/hal-03666596; https://hal.archives-ouvertes.fr/hal-03666596/document; https://hal.archives-ouvertes.fr/hal-03666596/file/Coombs%20et%20al%202022.pdf; https://doi.org/10.1016/j.cub.2022.04.060

International audience The evolution of cetaceans (whales and dolphins) represents one of the most extreme adaptive transitions known, from terrestrial mammals to a highly specialized aquatic radiation that includes the largest animals alive today. Many anatomical shifts in this transition involve the feeding, respiratory, and sensory structures of the cranium, which we quantified with a high-density, three-dimensional geometric morphometric analysis of 201 living and extinct cetacean species spanning the entirety of their ∼50-million-year evolutionary history. Our analyses demonstrate that cetacean suborders occupy distinct areas of cranial morphospace, with extinct, transitional taxa bridging the gap between archaeocetes (stem whales) and modern mysticetes (baleen whales) and odontocetes (toothed whales). This diversity was obtained through three key periods of rapid evolution: first, the initial evolution of archaeocetes in the early to mid-Eocene produced the highest evolutionary rates seen in cetaceans, concentrated in the maxilla, frontal, premaxilla, and nasal; second, the late Eocene divergence of the mysticetes and odontocetes drives a second peak in rates, with high rates and disparity sustained through the Oligocene; and third, the diversification of odontocetes, particularly sperm whales, in the Miocene (∼18-10 Mya) propels a final peak in the tempo of cetacean morphological evolution. Archaeocetes show the fastest evolutionary rates but the lowest disparity. Odontocetes exhibit the highest disparity, while mysticetes evolve at the slowest pace, particularly in the Neogene. Diet and echolocation have the strongest influence on cranial morphology, with habitat, size, dentition, and feeding method also significant factors impacting shape, disparity, and the pace of cetacean cranial evolution.