A new stem-tetrapod fish from the Middle–Late Devonian of central Australia

Abstract

ABSTRACT Remote Devonian exposures in central Australia have produced significant but highly fragmentary remains of fish-grade tetrapodomorphs. We describe a new tetrapodomorph from the Middle–Late Devonian (Givetian–Frasnian) Harajica Sandstone Member of the Amadeus Basin, Northern Territory, which is represented by several nearly complete skulls along with much of the body and postcranial skeleton. The new form has a posteriorly broad postparietal shield, broad, triangular extratemporal bones, and a lanceolate parasphenoid. The spiracular openings are particularly large, a character also recorded in elpistostegalians and Gogonasus, demonstrating that these structures, suggestive of spiracular surface air-breathing, appeared independently in widely differing nodes of the stem-tetrapod radiation. A phylogenetic analysis resolves the new form within a cluster of osteolepidid-grade taxa, either as part of a polytomy or as the most basally branching representative of a clade containing ‘osteolepidids,’ canowindrids, and megalichthyids.