Taxonomy and ontogeny of Ischnacanthus (Pisces: Acanthodii: Ischnacanthiformes) from the Lower Devonian (Lochkovian), Northwest Territories, Canada
Dates
Year
2003
Citation
Hermus, Chelsea Rae, 2003, Taxonomy and ontogeny of Ischnacanthus (Pisces: Acanthodii: Ischnacanthiformes) from the Lower Devonian (Lochkovian), Northwest Territories, Canada: University of Alberta (Canada).
Summary
Several new species of the ischnacanthiform acanthodian Ischnacanthus are described from a Lower Devonian (Lochkovian) fossil locality in the Mackenzie Mountains, Northwest Territories, Canada. These new species are distinguished based on features of the jaws, teeth, and tooth bearing bones. Ischnacanthus gracilis , a similar species from the Old Red Sandstone of Scotland, is not found at the Canadian fossil site. The presence of a range of sizes of specimens of Ischnacanthus suggests a growth series (juvenile to adult). The genus is found to develop in a largely isometric manner, with a few body proportions exhibiting slight allometry. Inability to diagnose species based on body fossils of Ischnacanthus implies that naming ischnacanthiform [...]
Summary
Several new species of the ischnacanthiform acanthodian Ischnacanthus are described from a Lower Devonian (Lochkovian) fossil locality in the Mackenzie Mountains, Northwest Territories, Canada. These new species are distinguished based on features of the jaws, teeth, and tooth bearing bones. Ischnacanthus gracilis , a similar species from the Old Red Sandstone of Scotland, is not found at the Canadian fossil site. The presence of a range of sizes of specimens of Ischnacanthus suggests a growth series (juvenile to adult). The genus is found to develop in a largely isometric manner, with a few body proportions exhibiting slight allometry. Inability to diagnose species based on body fossils of Ischnacanthus implies that naming ischnacanthiform species from isolated jaw elements, a widely used practice, is acceptable based on the abundance of diagnostic characters of the jaws and teeth and absence of such characters from other regions of the body.
