In a paper published in 2021 I described in collaboration with Luiz Carlos Weinschütz and Matt Friedman the first occurrence of a ray-finned fish from the circumpolar shallow seas of the Ponta Grossa Formation in southern Brazil. This occurrence not only expands the range of Devonian ray-finned fishes but also provide important data on morphological disparity and posible divergence times for important lineages.
Artwork of the new species Austelliscus ferox by the artist Julio Lacerda.
The morphology of the jaw of Austelliscus is surprisingly differentiated from ray-finned fishes of similar age, and very closely resembles that of the Late Devonian Tegeolepis clarkii from North America. This morphological similarity is supported by the phylogenetic analysis conducted in our work, where Austelliscus and Tegeolepis seem to be closely related. Thus, considering the age difference between these two and the age of other known Devonian ray-finned fishes Austelliscus highlights the presence of large ghost lineages in the early evolutionary history of the clade.
The presence of this fish in the Early-Middle Devonian deposits of South America indicates that important events in the early evolution of ray-finned fishes might have occurred in high-latitude shallow seas in the southern hemisphere and that the current understanding of Devonian ray-finned fishes based almost exclusively on paleotropical taxa might be highly biased.
These gaps in the knowledge could be filled with a better sampling of fish occurrences in the Ponta Grossa Formation and similar localities in South America and Africa.
Figueroa, R.T., Weinschütz, L.C. and Friedman, M. The oldest Devonian circumpolar ray-finned fish? Biology Letters, 17: 20200766. doi: 0.1098/rsbl.2020.076
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