Northern Pygmy Right Whales Highlight Quaternary Marine Mammal

Current Biology Magazine B Extant Correspondence A -120 -90 -60 -30 0 30 60 Caperea 0 USNM 358972 Northern pygmy 1 MSNC 4451 USNM MSNC 4451 Northern right whales 2 hemisphere 358972 Pleistocene highlight Quaternary 3 Northern Miocaperea hemisphere marine mammal pulchra 4 glaciation Pliocene interchange Extant Caperea marginata 5 MPEF-PV2572 NMV NMV P161709 6 P161709 Cheng-Hsiu Tsai1,2,15, Alberto 3,4,15 5,6 C 7 Miocaperea Collareta , Erich M.G. Fitzgerald , 30 mm v pulchra 5,7,8, 1,9 a Felix G. Marx *, Naoki Kohno , 8 8,10 11 Mark Bosselaers , Gianni Insacco , Miocene Delicate attachment Agatino Reitano11, Rita Catanzariti12, 9 of anterior process Southern hemisphere 13,14 Masayuki Oishi , Enlarged compound 10 MPEF-PV2572 3 posterior process and Giovanni Bianucci D The pygmy right whale, Caperea 30 mm marginata, is the most enigmatic living whale. Little is known about its ecology and behaviour, but unusual specialisations of visual pigments Prominent [1], mitochondrial tRNAs [2], and Squared anterior 20 mm E border of bulla anteromedial postcranial anatomy [3] suggest a corner lifestyle different from that of other extant whales. Geographically, Caperea Flattened dorsal profile of involucrum represents the only major baleen F L-shaped whale lineage entirely restricted to involucrum the Southern Ocean. Caperea-like fossils, the oldest of which date to the Late Miocene, are exceedingly rare and likewise limited to the Southern Hemisphere [4], despite a more substantial history of fossil Convex medial sampling north of the equator. Two a margin of bulla a new Pleistocene fossils now provide m v unexpected evidence of a brief and relatively recent period in geological Figure 1. Pygmy right whales in the Northern and Southern hemispheres. history when Caperea occurred in the (A) Global map showing the presumed distribution of extant Caperea marginata (in blue), Caperea Northern Hemisphere (Figure 1A,B). fossils from the Northern Hemisphere (red squares), and Caperea-like fossils from the Southern The new material, referred to as Hemisphere (green squares). (B) Global sea-level change over time compared to the age of the fossils shown in (A). See Supplemental Information for data sources. Note the clustering of North- Caperea sp. and cf. Caperea, consists ern Hemisphere specimens during the Pleistocene. (C) Right periotic and compound posterior of, respectively, a fragmentary skull with process of extant Caperea marginata, NMV C28531, compared to Caperea sp., USNM 358972. ear bones (USNM 358972) from the (D) Tympanic bulla of extant Caperea marginata, NMNZ MM002119 (right bulla, mirrored horizon- upper portion of the Naha Formation tally for comparison), compared to (E) Caperea sp., USNM 358972 and (F) cf. Caperea, MSNC of Okinawa-jima, Japan (0.9–0.5 Ma) 4451. Drawing of Caperea by Carl Buell. and a tympanic bulla (MSNC 4451) from an unnamed deposit on Penisola profi le of the involucrum, in dorsal and a robust, conical and externally Maddalena, near Syracuse, Sicily, view (Figure 1C–F). USNM 358972 exposed compound posterior process Italy (1.9–1.7 Ma) (Supplemental furthermore shares with extant Caperea of the tympanoperiotic (Figure 1C, Information). The tympanic bullae of the presence of: an elongate squamosal S2A–D,F). In the morphology of both specimens are highly diagnostic, fossa; a foramen pseudovale enclosed the foramen pseudovale and the and identifi able based on their: entirely by the pterygoid; a narrow, connection of the anterior process rectangular Eustachian outlet; fl attened sulcus-like Eustachian notch; a delicate to the periotic, USNM 358972 differs involucrum lacking any sign of an inner connection between the anterior from the only named extinct relative of posterior prominence; broadly convex process and the body of the periotic; an Caperea — Miocaperea pulchra, from medial margin; prominent, angular anteriorly directed anteroexternal sulcus the Late Miocene of Peru [5]. MSNC anteromedial corner; and L-shaped on the anterior process of the periotic; 4451 and Miocaperea currently cannot R1058 Current Biology 27, R1037–R1059, October 9, 2017 © 2017 Elsevier Inc. Current Biology Magazine be compared, as the bulla morphology play a major role in marine mammal established their provenance and age. F.G.M, remains unknown for the latter. evolution [6,7]. The Pleistocene E.M.G.F. and G.B. organised the collaborative Nevertheless, the notable similarity of with its constant change between project. All authors discussed and wrote the MSNC 4451 and living pygmy right glacial and interglacial conditions is paper. whales justifi es referral to cf. Caperea. a prime example, with the relaxation The Northern Hemisphere material and subsequent re-establishment of REFERENCES of Caperea could conservatively be an equatorial barrier driving range 1. Meredith, R.W., Gatesy, J., Emerling, C.A., interpreted as extralimital occurrences extensions, speciations and, in the York, V.M., and Springer, M.S. (2013). Rod of the living species, yet it also case of Caperea, local extinctions. A monochromacy and the coevolution of cetacean retinal opsins. 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Science 312, 1485–1489. of marine faunal interchange during of current marine mammal ranges, the Pleistocene than hitherto assumed, with implications for future speciation 1Department of Geology and Palaeontology, and that this interchange affected and, crucially, extinction. For example, National Museum of Nature and Science, 2 even highly localised specialists. a warmer world might see poleward Tsukuba, 305-0005, Japan. Department of Geology, University of Otago, Dunedin, 9054, In light of our fi ndings, other highly range shifts among extant marine New Zealand. 3Dipartimento di Scienze della unusual occurrences, even southern mammals [9] and the establishment Terra, Universitá di Pisa, Pisa, 56126, Italy. walruses and northern penguins, of a ‘permanent’ El Niño state in the 4Dottorato Regionale in Scienze della Terra should be anticipated. The fact

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