Review of the osteology of the fossil fish formerly attributed to the genus †Chanoides and implications for the definition of otophysan bony characters

Abstract

Three fossil species were formerly referred to the stem otophysan genus †Chanoides: †C. macropoma from the Middle Eocene of Monte Bolca, Italy, ‘†Chanoides’ chardoni from the Campano–Maastrichtian of Nardò, Italy, and †C. weberi from the Santonian of Apricena, Italy. Moreover, a monogeneric family Chanoididae was proposed as a consequence of the 40 million year range covered by this fossil record. The stem position of these species amongst otophysans, a large clade with debated interrelationships, leads us to review their anatomy with the double aim of improving their systematics and bringing new elements to understand otophysan character evolution. We clarify the anatomy of the two valid species †C. macropoma and ‘†Chanoides’ chardoni, including reinterpretation of the ethmovomerian and maxillary regions, Weberian structures and caudal skeleton; we invalidate †C. weberi nom. dub. and include ‘†C.’ chardoni in the new genus †Nardonoides; we discuss the bony apomorphies of the otophysan clade as a whole and the orders included in it and notably propose to retain only the presence of a Weberian apparatus as the apomorphy to define Otophysi.

http://zoobank.org/urn:lsid:zoobank.org:pub:E82A326C-1A35-4AC7-9C7F-778C3032A309

Keywords:

• †Chanoides
• †Nardonoides gen. nov.
• Otophysi
• osteology
• relationships
• Maastrichtian
• Eocene

Acknowledgements

We would like to thank Dr Zerina Johanson for loan of the specimens housed in the Palaeontological Collection of the Natural History Museum, London, and Dr Anna Vaccari from the Museo Civico di Storia Naturale di Verona. We would like to thank Lionel Cavin and Gloria Arratia for their invaluable comments. D. Mayrinck is supported by a post-doctoral fellowship from CAPES/FAPERJ [process E-26/102.444/2010]; by a CNPq grant [process 481021/2011-6]; and by F. Ortega Stonis philanthropical association; P. M. Brito is supported by CNPq (Conselho Nacional de Pesquisa, Brazil), FAPERJ (Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro) and ‘Prociência’ grants.