Anatomical revision and homology problems concerning the outstanding osteichthyan Dialipina salgueiroensis from the Devonian of the Canadian Arctic

Dialipina salgueiroensis was described first by Schultze (1968) based solely on its characteristic scales that resemble palaeoniscoids. Numerous specimens in different states of preservation, including a few complete ones, were recovered later in the Canadian Arctic, permitting a more comprehensive description of this unusual fish. During the last 26 years, numerous publications have addressed the possible phylogenetic position of Dialipina either as a stem osteichthyan or stem actinopterygian based mainly on cranial information and scales, which are characteristically ornamented. Dialipina has an outstanding combination of features, such as the presence of two dorsal fins and a triphycercal tail bearing basal and fringing fulcra. Additionally, it exhibits a variable number of bones in the lateral side of the head that makes comparison difficult. For example, there is a preopercular region represented by various anamestic bones, but a sensory canal has not been identified for this or any other bone of the lateral head. New interpretations on the structure of the fins and on the cranium are presented, especially its anterior and posterior regions. Thus, the main goal of this contribution is to restudy Dialipina salgueiroensis, which includes reinterpreting some characters and describing new ones that are based on older and newly collected specimens. Consequently, the generic and specific diagnoses are revisited, and a family diagnosis is proposed as well, with Dialipina classified as a basal osteichthyan of order Dialipiniformes in its own, new family as a monotypic genus and species