A review of recent discoveries of exceptionally preserved fossil fishes from the Gogo sites (Late Devonian, Western Australia)

Abstract

Significant new material of Late Devonian Gogo Formation fish fossils is still surfacing. Collecting in the past decade has uncovered the first Gogo shark fossils (Gogoselachus plus another new undescribed taxon), the first acanthodian (Halmacanthodes ahlbergi), the first coelacanth, as well as the first placoderm embryos. Recent studies have elucidated the nature of placoderm claspers, pelvic girdles, synarcuals and embryos, the structure of their teeth, a description of well-preserved muscles in placoderms, and how muscles attach to bones. Molecular biomarkers have also been identified in Gogo fossils. There are now five basal ray-fin fishes in the fauna, including one undescribed new taxon. The lungfish fauna from Gogo is the most diverse known for any Devonian site, with 10 genera and 12 species. The dermal skeleton and endocast of the dipterid Rhinodipterus kimberleyensis have been described in detail from CT scans; and the ontogenetic stages of neurocranium formation in Griphognathus. New specimens of the tetrapodomorph fish Gogonasus andrewsae have shed further light on its endocranium, pectoral girdle and fin. Through their exceptional preservation of both hard and varied kinds of soft tissues, the Gogo fishes remain crucial for resolving key debates on the diversification, physiology, biomechanics and phylogenetic relationships of early gnathostomes.