Identification of the Bones of the Snout in Fossil Lower Actinopterygians—A New Nomenclature Scheme Based on Characters

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Currently, there is no standardized nomenclatural scheme for identifying and naming the bones of the snout in lower actinopterygians and specifically those fishes referred to as palaeoniscoids. A literature review reveals that the same bone names are used by different researchers to identify very different bones. This lack of homogeneity is problematic because it makes comparisons among taxa difficult, impairs our understanding of the morphological diversity of lower actinopterygians, and presents potential pitfalls when building character matrices for phylogenetic analyses. Because of the problems the absence of a standardized nomenclature scheme presents, a new set of rules for the identification of the bones of the snout of lower actinopterygians is proposed. These definitions are based on characters that are commonly preserved such as the presence of sensory canals, location of bones in relation to other bones, and whether or not the bones contribute to forming nasal openings. When numerous characters...