The skull and pectoral girdle of the parasemionotid fishWatsonulus eugnathoidesfrom the Early Triassic Sakamena Group of Madagascar, with comments on the relationships of the holostean fishes

Watsonulus eugnathoides (Piveteau, 1935) is a parasemionotid fish from Early Triassic rocks of Madagascar. The skull and pectoral girdle of this holostean are described from new material. The braincase retains a number of primitive chondrostean-like characters such as an open lateral cranial fissure and frequently open vestibular fontanelle, presence of an endochondral intercalar without membranous outgrowths, and fusion between most of the the endochondral bones in the adult, but is otherwise similar to “caturids” such as Heterolepidotus. The dermal skull retains one major, putatively primitive, feature shared with chondrosteans, a preopercular with a broad dorsal edge. The dermal shoulder girdle retains a chondrostean-style clavicle, but the endochondral shoulder girdle is most similar to teleosts among actinopterygians. Watsonulus also has an Amia-style jaw joint. The non-reduced clavicle and dorsally expanded preoperculum are lost in all other non-parasemionotid neopte-rygians (the reductions being synapomorphies), and the combination of these two primitive characters with an Amia-style jaw in Watsonulus shows that gars and teleosts are more closely related to each other than either is to Amia.