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| Austelliscus ferox Figueroa, Weinschütz & Friedman, 2021 |
Abstract
Actinopterygians (ray-finned fishes) are the most diverse group of living fishes, but have a sparse Devonian fossil record restricted to low palaeolatitudes. Here we report a new actinopterygian from the Paraná Basin of Brazil, which occupied a circumpolar position in the Palaeozoic. Available geological evidence supports a Middle Devonian or older age for this taxon, which shares features of the mandibular symphysis with the latest Devonian Tegeolepis. A phylogenetic analysis resolves these two as sister taxa. This new record expands the palaeogeographic distribution of Devonian ray-fins and suggests that gaps in their fossil record might be filled by exploring poorly sampled high-latitude localities within the Malvinokaffric Realm.
Keywords: Osteichthyes, Actinopterygii, Malvinokaffric, palaeopolar, Devonian, Brazil
Subjects
Systematic palaeontology
Osteichthyes Huxley, 1880
Actinopterygii Cope, 1887
Austelliscus ferox gen. et sp. nov.
Etymology: The generic name references the high palaeolatitude locality (austelli, from the Latin meaning ‘the southern portion'), combined with the Latin suffix for ‘fish' (iscus). Species epithet alludes to the large teeth of the specimen (ferox, from the Latin meaning ‘ferocious').
Generic diagnosis: Actinopterygian with robust, conical, anteriorly oriented teeth on the dentary, except for the symphysis where teeth point posteriorly; symphysis reflexed posteriorly; jaw ramus constricted posterior to the symphysis. Differs from Tegeolepis in having: large oval replacement sockets in the lingual tooth row (rather than circular); lingual and labial tooth series converge posteriorly (rather than remaining well separated); more substantial post-symphyseal constriction of the dentary; the external surface of dentary ornamented with rounded tubercles anteroventrally and vermiform ornamentation posteriorly (rather than having only sparse tubercles and ridges).
Holotype: MCT890-P, the mould of an incomplete left dentary in part and counterpart.
Rodrigo Tinoco Figueroa, Luiz Carlos Weinschütz and Matt Friedman. 2021. The Oldest Devonian Circumpolar Ray-finned Fish? Biology Letters. DOI: 10.1098/rsbl.2020.0766
