The cochlea of the enigmatic pygmy right whale Caperea marginata informs mysticete phylogeny.
The pygmy right whale, Caperea marginata, is the least understood extant baleen whale (Cetacea, Mysticeti). Knowledge on its basic anatomy, ecology, and fossil record is limited, even though its singular position outside both balaenids (right whales) and balaenopteroids (rorquals + grey whales) gives Caperea a pivotal role in mysticete evolution. Recent investigations of the cetacean cochlea have provided new insights into sensory capabilities and phylogeny. Here, we extend this advance to Caperea by describing, for the first time, the inner ear of this enigmatic species. The cochlea is large and appears to be sensitive to low-frequency sounds, but its hearing limit is relatively high. The presence of a well-developed tympanal recess links Caperea with cetotheriids and balaenopteroids, rather than balaenids, contrary to the traditional morphological view of a close Caperea-balaenid relationship. Nevertheless, a broader sample of the cetotheriid Herpetocetus demonstrates that the presence of a tympanal recess can be variable at the specific and possibly even the intraspecific level.
School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.|Geosciences, Museum Victoria, Melbourne, Victoria, Australia.
Travis
0000-0002-9492-8859
T
Park
School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.|Geosciences, Museum Victoria, Melbourne, Victoria, Australia.|Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium.
Felix G
FG
Marx
Geosciences, Museum Victoria, Melbourne, Victoria, Australia.|National Museum of Natural History, Smithsonian Institution, Washington, DC.|Department of Vertebrate Zoology, Department of Life Sciences, Natural History Museum, London, United Kingdom.
Erich M G
EMG
Fitzgerald
School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.|Geosciences, Museum Victoria, Melbourne, Victoria, Australia.
Alistair R
AR
Evans
D000818:Animals; D003051:Cochlea / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005580:Fossils; D010802:Phylogeny; D014057:Tomography, X-Ray Computed; D014907:Whales / Q000033:anatomy & histology*
Cetacea; Plicogulae; hearing; tympanal recess