Morphological insights into the lobster genus Uncina Quenstedt, 1851 based on new material from the Ya Ha Tinda Konservat-Lagerstätte, Canada (Early Jurassic)

Abstract

It is rare to find Early Jurassic crustacean material outside of Europe but the discovery of the Ya Ha Tinda Konservat-Lagerstätte in Alberta, Canada, has significantly increased the number of crustacean specimens, specifically of the genus Uncina. New articulated specimens of Uncina pacifica and Uncina ollerenshawi preserve most of the cephalothorax and pleon, not just the chelae of the first pereiopod. This new material from Ya Ha Tinda permits revised morphologic descriptions as well as a quantitative analysis of the intra-and interspecific variability of Uncina claw morphology. Morphometric similarities and differences are noted between species, indicating that a notch at the distal end of the occlusal surface of the fixed finger is diagnostic for the genus. Our findings suggest that Uncina species are usually isochelous, with the exception of Uncina pacifica, which is heterochelous. The two co-occurring species of Uncina in the Ya Ha Tinda Formation, Uncina pacifica and Uncina ollerenshawi, likely occupied different niches, based upon differences in chela morphology.