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The Latero‐sensory Component of the Dermal Skeleton in Lower Vertebrates and Its Phyletic Significance
Author(s) -
Ørvig Tor
Publication year - 1972
Publication title -
zoologica scripta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.204
H-Index - 64
eISSN - 1463-6409
pISSN - 0300-3256
DOI - 10.1111/j.1463-6409.1972.tb00672.x
Subject(s) - phyletic gradualism , biology , anatomy , skeleton (computer programming) , sensory system , vertebrate , evolutionary biology , neuroscience , phylogenetics , genetics , gene
Ørvig, T. (Section of Palaeozoology, Swedish Museum of Natural History, Stockholm, Sweden.) The latero‐sensory component of the dermal skeleton in lower vertebrates and its phyletic significance . Zool. Scripta 1(3–4): 139–155, 1972.–A latero‐sensory component of the dermal skeleton is met with not only in teleostomian fishes, but also in arthrodires, holocephalians (the lateral line canal “rings”), some fossil selachians, bradyodonts and acanthodians, and a few, at least, of the Osteostraci. Although not yet traceable with certainty in the Heterostraci, such a component probably existed even in early stages of vertebrate history. The persistence in the adult of this component as separate ossicles embracing the lateral line canals is surely the result of regression or other modifications of the dermal skeleton in fishes like arthrodires, coelacanthids and actinopterygians, but is apparently a primitive feature in e.g. acanthodians. In discussing the phyletic relations between the latero‐sensory and membranous components of the dermal skeleton, it is concluded that these probably were separate formations from the very beginning. A condition (exemplified by certain acanthodians) where separate latero‐sensory ossicles of the lateral line canals are surrounded by a mosaic of small scales of membranous origin is presumably that from which the various dermal bone‐patterns in lower vertebrates are all derived. A discussion is also included in this paper of the scales and otoliths in acanthodians.