Convergent Evolution of Swimming Adaptations in Modern Whales Revealed by a Large Macrophagous Dolphin from the Oligocene of South Carolina.

Autor:	Boessenecker RW; Department of Geology and Environmental Geosciences, College of Charleston, Charleston, SC 29424, USA; University of California Museum of Paleontology, University of California, Berkeley, CA 94720, USA. Electronic address: boesseneckerrw@cofc.edu., Churchill M; Department of Biology, University of Wisconsin-Oshkosh, Oshkosh, WI 54901, USA., Buchholtz EA; Department of Biological Sciences, Wellesley College, Wellesley, MA 02481, USA., Beatty BL; Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA., Geisler JH; Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA.
Jazyk:	angličtina
Zdroj:	Current biology : CB [Curr Biol] 2020 Aug 17; Vol. 30 (16), pp. 3267-3273.e2. Date of Electronic Publication: 2020 Jul 09.
DOI:	10.1016/j.cub.2020.06.012
Abstrakt:	Modern whales and dolphins are superbly adapted for marine life, with tail flukes being a key innovation shared by all extant species. Some dolphins can exceed speeds of 50 km/h, a feat accomplished by thrusting the flukes while adjusting attack angle with their flippers [1]. These movements are driven by robust axial musculature anchored to a relatively rigid torso consisting of numerous short vertebrae, and controlled by hydrofoil-like flippers [2-7]. Eocene skeletons of whales illustrate the transition from semiaquatic to aquatic locomotion, including development of a fusiform body and reduction of hindlimbs [8-11], but the rarity of Oligocene whale skeletons [12, 13] has hampered efforts to understand the evolution of fluke-powered, but forelimb-controlled, locomotion. We report a nearly complete skeleton of the extinct large dolphin Ankylorhiza tiedemani comb. n. from the Oligocene of South Carolina, previously known only from a partial rostrum. Its forelimb is intermediate in morphology between stem cetaceans and extant taxa, whereas its axial skeleton displays incipient rigidity at the base of the tail with a flexible lumbar region. The position of Ankylorhiza near the base of the odontocete radiation implies that several postcranial specializations of extant cetaceans, including a shortened humerus, narrow peduncle, and loss of radial tuberosity, evolved convergently in odontocetes and mysticetes. Craniodental morphology, tooth wear, torso vertebral morphology, and body size all suggest that Ankylorhiza was a macrophagous predator that could swim relatively fast, indicating that it was one of the few extinct cetaceans to occupy a niche similar to that of killer whales. Competing Interests: Declaration of Interests The authors declare no competing interests. (Copyright © 2020 Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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