Dear colleagues, please find below the abstract and link to our recently published, open access paper on a new fossil baleen whale from Peru, and its implications for the origin of cetotheriids: Marx F.G., Lambert O., de Muizon C. 2017 A new Miocene baleen whale from Peru deciphers the dawn of cetotheriids. R Soc Open Sci 4, 170560. Link: http://rsos.royalsocietypublishing.org/content/4/9/170560 Abstract: Cetotheriidae are an iconic, nearly extinct family of baleen whales (Mysticeti) with a highly distinct cranial morphology. Their origins remain a mystery, with even the most archaic species showing a variety of characteristic features. Here, we describe a new species of archaic cetotheriid, Tiucetus rosae, from the Miocene of Peru. The new material represents the first mysticete fromthe poorly explored lowest portion of the highly fossiliferous Pisco Formation (allomember P0), and appears to form part of a more archaic assemblage than observed at the well-known localities of Cerro Colorado, Cerro los Quesos, Sud-Sacaco and Aguada de Lomas. Tiucetus resembles basal plicogulans (crown Mysticeti excluding right whales), such as Diorocetus and Parietobalaena, but shares with cetotheriids a distinct morphology of the auditory region, including the presence of an enlarged paroccipital concavity. The distinctive morphology of Tiucetus firmly places Cetotheriidae in the context of the poorly understood ‘cetotheres’ sensu lato,and helps to resolve basal relationships within crown Mysticeti. Kind regards, Felix Marx _____________________________ *Felix G. Marx* PhD Marie Skłodowska-Curie Postdoctoral Fellow *Royal Belgian Institute of Natural Sciences, Brussels, Belgium *Monash University, Melbourne, Australia *Museum Victoria, Melbourne, Australia Address: School of Biological Sciences, Monash University 18 Innovation Walk, VIC 3800, Australia Tel. +61 (0)3 9905 1190 (Monash University) or +61 (0)3 8341 7346 (Museum Victoria)