New Pliocene right whale from Belgium informs balaenid phylogeny and function

Abstract

Right whales (Balaenidae) are the most distinctive family of extant baleen whales, thanks to their highly arched rostrum, tall lips and robust body shape. They are also the oldest, originating as much as 20 million years ago (Ma). Nevertheless, their fossil record is patchy and frequently understudied, obscuring their evolution. Here, we describe a new stem balaenid, Antwerpibalaena liberatlas, from northern Belgium, adding to the rich but historically problematic baleen whale assemblage of the Pliocene North Sea. Within right whales, Antwerpibalaena forms a clade with two previously described extinct genera, Balaenella and Balaenula. The holotype preserves much of the postcranial skeleton, and informs the emergence of typical balaenid traits like fused neck vertebrae and paddle-shaped flippers. Its size is intermediate between that of extant right whales and most of their extinct forebears revealing a more complex pattern of balaenid size evolution than previously thought.

http://zoobank.org/urn:lsid:zoobank.org:pub:A0070739-C6A3-42DE-B0A4-B309EF18DAFE

Keywords:

• Balaenidae
• gigantism
• cervical vertebrae
• ear bones
• forelimb
• phylogeny

Acknowledgements

We thank T. Kimura, M. Buono and R. E. Fordyce for their constructive reviews; M. Reyns, R. Sieckelink and N. Ouifak of ‘Mobiliteit en Openbare Werken (MOW)’ for granting access to the construction site and assistance during the excavation; R. E. Fordyce for his photo of NMNZ MM002239; C. Buell for his drawing of a balaenid; and (in alphabetical order) S. Berton, E. Dermience, K. Hoedemakers, P. De Saegher, M. Spolspoel, R. Marquet, T. Lambrechts, J. Segers, J. Van Boeckel, F. Vanderlinden and D. Vanhove for help with the excavation and preparation of the specimen. CT scanning was carried out as part of the DiSSCo-FED project of the IRSNB. This work was carried out as part of an internship (to GDdL) organized by the universities of Poitiers and Montpellier, and supported by an FNRS postdoctoral fellowship (32795797) to FGM, as well as a Marie Skłodowska-Curie Individual Fellowship (748167/ECHO) to TP, who was also partially funded by ERC Starting Grant (677774/TEMPO).

Associate Editor: Pip Brewer