The internal anatomy of mysticete periotica and the evolution and development of low frequency hearing in baleen whales
Final Report Abstract
Our results of the cochlear coiling shape analysis suggests that a shift of the frequency range towards the lower end, including the ability to hear very low and infrasonic frequencies, is associated with compact coiling, a non-gradual ascent of the basilar membrane, the basal end of the basilar membrane below the level of the basal turn, the second turn protruding over the basal turn, a descending apex, and a high number of turns (2.2 or above). Furthermore, low lf hearing limits occur in cetaceans with longer cochleae. Very low-frequency hearing (50 Hz and below) had likely evolved by the middle Miocene, and infrasonic hearing (below 20 Hz) had evolved by the late Miocene. Even the earliest Chaeomysticeti were probably able to hear frequencies of 100 Hz and below, and the ability to hear low frequencies within the audible range may be ancestral to all Neoceti. Cochlear coiling shape proved useful for inferring hearing range, as did number of turns and cochlear length times number of turns. Radii ratio is not directly connected to lf hearing in our study, and, to date, the method has not been used in a standardized, comparable manner.
Publications
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2013. Capability to use LF sound as an evolutionary advantage in opening up new habitats during a time of global ocean and climate change. – 20th Biennial Conference on the Biology of Marine Mammals, 2013 Dunedin, New Zealand, December 9-13, Abstracts, 180; Dunedin
Ritsche, I.S., Wieder, F. & Hampe, O.
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2013. Whale ears inside and out: are low-frequency hearing and cranial shape related in early baleen whales (Cetacea, Mysticeti)? – A Joint Conference of the “Paläontologische Gesellschaft” and the “Palaeontological Society of China”, Göttingen, Germany, September 23-27, 2013. Pages 43-44 in: Reitner, J., Yang, Q., Wang, Y. & Reich, M. (eds.) Palaeobiology and Geobiology of Fossil Lagerstätten through Earth History, Universitätsverlag Göttingen
Fahlke, J.M., Ritsche, I.S. & Hampe, O.
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2014. Did whales straighten up to hear better? Potential connection between cranial symmetry and low-frequency hearing in mysticetes (Cetacea). – 7th Triennial Conference on Secondary Adaptations of Tetrapods to Life in Water, Fairfax, VA, and Washington, D.C., USA, June 2-4, 2014
Fahlke, J.M., Ritsche, I.S. & Hampe, O.
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2016. Phylogenetic signal or functional analogy in cochlear shape of Mysticeti. – 5th International Geologica Belgica 2016 Congress, 26-29 January 2016. Abstract Book, 243; University of Mons
Ritsche, I., Fahlke, J.M. & Hampe, O.
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(2018) Relationships of cochlear coiling shape and hearing frequencies in cetaceans, and the occurrence of infrasonic hearing in Miocene Mysticeti. Foss. Rec. (Fossil Record) 21 (1) 33–45
Ritsche, Indira S.; Fahlke, Julia M.; Wieder, Frank; Hilger, André; Manke, Ingo & Hampe, Oliver
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2017. Relationships of cochlear coiling shape and hearing capabilities in Mysticeti. – Secondary adaptation of tetrapods to life in water, 8th International Meeting April 3–8, 2017, page 34 in: Hampe, O., Schwarz, D. & Voss, M. (eds.), PinguinDruck, Berlin
Ritsche, Indira S.; Fahlke, Julia M.; Wieder, Frank; Hilger, André; Manke, Ingo & Hampe, Oliver
