Abstract
The origin of the pygmy right whale (Caperea marginata) has long been one of the most vexing conundrums of marine mammal evolution. The extremely disparate skeletal structure of Caperea and a patchy fossil record have left morphology and molecules at odds: whereas most morphological analyses ally Caperea with right whales (Balaenidae), most molecular studies instead suggest a close relationship with rorquals (Balaenopteridae) and grey whales (Eschrichtiidae). The morphological evidence supporting a Caperea-balaenid clade consists of several shared features of the skull and mandible, as traditionally observed in adult individuals. Here, we show that at least two of these features, the ascending process of the maxilla and the coronoid process, arise from substantially different precursors early during ontogeny and therefore likely do not represent genuine synapomorphies. Both of these juvenile morphologies have adult counterparts in the fossil record, thus indicating that the ontogenetic variation in the living species may be a genuine reflection of differing ancestral states. This new evidence contradicts previous morphological hypotheses on the origins of Caperea and may help to reconcile morphological and molecular evidence.
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References
Bisconti M (2012) Comparative osteology and phylogenetic relationship of Miocaperea pulchra, the first fossil pygmy right whale genus and species (Cetacea, Mysticeti, Neobalaenidae). Zool J Linn Soc Lond 166:876–911
Boessenecker RW (2011) Herpetocetine (Cetacea: Mysticeti) dentaries from the Upper Miocene Santa Margarita Sandstone of Central California. PaleoBios 30:1–12
Buono MR, Dozo MT, Marx FG, Fordyce RE (2012) A new fossil mandible from the Late Miocene of Argentina sheds light on the deep-time origins of the enigmatic pygmy right whale. Acta Palaeontol Pol, accepted with minor revisions
Cabrera A (1926) Cetáceos fósiles del Museo de La Plata. Rev Mus La Plata 29:363–411
Churchill M, Berta A, Deméré TA (2012) The systematics of right whales (Mysticeti: Balaenidae). Mar Mamm Sci 28:497–521
Deméré TA, McGowen MR, Berta A, Gatesy J (2008) Morphological and molecular evidence for a stepwise evolutionary transition from teeth to baleen in mysticete whales. Syst Biol 57:15–37
De Pinna MGG (1991) Concepts and tests of homology in the cladistic paradigm. Cladistics 7:367–394
Ekdale EG, Berta A, Deméré TA (2011) The comparative osteology of the petrotympanic complex (ear region) of extant baleen whales (Cetacea: Mysticeti). PLoS One 6:e21311
Fitzgerald EMG (2012) Possible neobalaenid from the Miocene of Australia implies a long evolutionary history for the pygmy right whale Caperea marginata (Cetacea, Mysticeti). J Vertebr Paleontol 32:976–980
Fordyce RE, Marx FG (2012) The pygmy right whale Caperea marginata—the last of the cetotheres. Proc Roy Soc B 280:20122645
Geisler JH, McGowen MR, Yang G, Gatesy J (2011) A supermatrix analysis of genomic, morphological, and paleontological data from crown Cetacea. BMC Evol Biol 11:112
Graf J, Jacobs L, Polcyn M, Mateus O, Schulp A (2011) New fossil whales from Angola. J Vert Paleontol Abstracts 2011:119
Kemper CM (2009) Pygmy right whale Caperea marginata. In: Perrin WF, Würsig B, Thewissen JGM (eds) Encyclopedia of marine mammals, 2nd edn. Academic, Burlington, pp 939–941
Marx FG (2011) The more the merrier? A large cladistic analysis of mysticetes, and comments on the transition from teeth to baleen. J Mammal Evol 18:77–100
McGowen MR, Spaulding M, Gatesy J (2009) Divergence date estimation and a comprehensive molecular tree of extant cetaceans. Mol Phylogenet Evol 53:891–906
Rieppel O, Kearney M (2002) Similarity. Biol J Linn Soc Lond 75:59–82
Steeman ME et al (2009) Radiation of extant cetacean driven by restructuring of the oceans. Syst Biol 58:573–585
Acknowledgments
We thank M. Churchill for providing photographs of LACM 54763, as well as D. J. Bohaska, M. Boller, E. Burns, E. Crespo, E. M. G. Fitzgerald, C. Francou, N. Garcia, E. R. Gomez, P. Holroyd, H. Karasawa, C. de Muizon, C. W. Potter, N.D. Pyenson, M. Reguero, A. Sanders, A. Van Helden, D. Verzi, and R. Ziegler for access to collections. We thank the editor and referees for their constructive comments. This research was supported by the following grants: Geoscience Society of New Zealand (Wellman Research Award), Systematics Association/Linnean Society of London (Systematic Research Fund), Scottish Association for Marine Science (Research Bursary), Paleontological Society (Stephen Jay Gould Award), University of Otago Postgraduate Scholarship and Publication Bursary, and Otago Museum Linnaeus Taxonomy Fellowship to FGM; Cetacean Society International (CSI), American Museum of Natural History (Lerner Gray Fund for Marine Research), Society for Marine Mammalogy (Grant In Aid of Research), and Smithsonian Institution (Remington Kellogg Fund) to MRB; and University of Otago-Geology PBRF funds to REF.
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Communicated by: Sven Thatje
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Marx, F.G., Buono, M.R., Fordyce, R.E. et al. Juvenile morphology: A clue to the origins of the most mysterious of mysticetes?. Naturwissenschaften 100, 257–261 (2013). https://doi.org/10.1007/s00114-013-1012-y
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DOI: https://doi.org/10.1007/s00114-013-1012-y