Skip to main content
Dryad logo

Data from: Unraveling species concepts for the Helicoprion tooth whorl

Citation

Tapanila, Leif; Pruitt, Jesse (2013), Data from: Unraveling species concepts for the Helicoprion tooth whorl, Dryad, Dataset, https://doi.org/10.5061/dryad.q64g3

Abstract

The genus Helicoprion (Chondricthyes: Euchondrocephali) is preserved primarily by a continuous spiral root that forms the base for more than 130 teeth. Helicoprion is found globally in Lower Permian marine rocks and at least 100 specimens exist in public collections worldwide. Ten species of the genus are reviewed in the context of new morphometric analyses conducted on dozens of specimens. Helicoprion whorls share a common inner spiral geometry that results in exponential growth of tooth and root dimensions. Novel growth equations permit calculation of whorl diameter, volution number and tooth count from incomplete specimens. The results of meristic and geometric analyses identify taxobases that distinguish three emended species concepts. Differentiation of form is evident among specimens only after the second volution or roughly the 85th tooth. Helicoprion davisii has widely-spaced, stout teeth with tall cutting surfaces and is distinguished from H. bessonowi, whi ch has narrow, closely-spaced teeth with short cutting surfaces. H. ergassaminon is an intermediate form, having narrow, closely-spaced teeth with tall cutting surfaces. Several large specimens in the study are too dissimilar to place in the new emended species concepts.

Usage Notes

Location

Western Australia
Canada
Ural Mountains
China
Japan
Svalbard
California
Idaho
Nevada