AN EMPIRICAL SYNTHETIC PATTERN STUDY OF GARS (LEPISOSTEIFORMES) AND CLOSELY RELATED SPECIES, BASED MOSTLY ON SKELETAL ANATOMY. THE RESURRECTION OF HOLOSTEI

• Published in: Copeia Vol. 10; no. 2A; p. 1
• Main Author: Grande, Lance
• Format: Journal Article
• Language: English
• Published: Lawrence American Society of Ichthyologists and Herpetologists 04-10-2010
• Subjects: Biogeography; Bones; Fish; Fossils; Morphology; Paleoecology; Paleontology
• ISSN: 2766-1512; 2766-1520

The comparative osteology, phylogenetic relationships, and historical biogeography of all known fossil and living gars (Ginglymodi: Lepisosteiformes) are investigated in detail. Clearly documented comparative data on the skeletons of lepisosteiforms and closely related taxa are examined with regard to phylogeny, ontogeny, historical biogeography, stratigraphic paleontology, and paleoecology. This study of lepisosteiform fishes is also used as a platform to explore several fundamental methodological and philisophical concepts important to phylogenetic/evolutionary investigations (pp. 819-828). The seven extant species of gars are the sole surviving members of a formerly diverse "division" of fishes, Ginglymodi (here including Lepisosteiformes, [dagger]Semionotiformes, and [dagger]Macrosemiiformes). Even Lepisosteiformes (the ginglymodin subgroup that is the focus of this study) was much more diverse taxonomically and morphologically during Mesozoic and Paleogene times than it is today. It was also much more geographically widespread. Lepisosteiformes, as defined here, are those neopterygian fishes with opisthocoelous vertebral centra, "tongue bones" (a basihyal tooth plate consisting of bony plates or "entoglossals"), dorsal fin set far posterior on body (predorsal length of 75-88% of standard length) and several other uniquely derived morphological characters. To set the style and terminology for description of the fossil taxa, and to present a fresh look at the osteology and development of living gars, the skeletal anatomy of Lepisosteus osseus and Atractosteus spatula is redescribed in great detail, and the other five extant gars in somewhat less but still significant detail, all using modern methods of preparation and illustration. Such detailed study of the extant species was necessary to adequately interpret probable intraspecific variation and ontogenic variation in fossil taxa. Individual variation of both bone morphology and developmental timing in Lepisosteus osseus is also examined. [PUBLICATION ABSTRACT]