Jonathan Sargent, “Pinches for Prehistory: Investigating the Maximum Pinch Forces of Fossil Scorpions via Comparative Analysis with Modern Scorpion Chela Morphology and Pinch Force”
Mentor: Victoria McCoy, Geosciences, Letters & Science (College of)
Poster #140
The chelae-telson tradeoff hypothesis in scorpions states that scorpions with less developed chelae possess the most potent venom and vice versa. This hypothesis is receiving increasing support from formal comparative studies in extant scorpions. Size-corrected pinch forces and chelae aspect ratios (length/height) display a high correlation, and phylogenetically independent contrasts indicate a correlation of chela width, height, and fixed finger length with maximum pinch force (n) independent of phylogeny. This provides a potential comparative framework to estimate the size-corrected and actual pinch forces in fossil scorpions, which would allow semi-quantitative interpretations of their feeding and defensive strategies. Ten fossil scorpion specimens were selected for the study because they met the following criteria: at least one completely preserved chela; a completely preserved prosoma and mesosoma; and a prosoma and mesosoma length (PML) within the range (2.36 – 6.36 cm) of studied extant scorpions. Estimating specimens’ size-corrected and actual maximum pinch force (n) occurred via multiple regressions of the size-corrected residuals of their chelae aspect ratio, according to the provided size-corrected maximum pinch force vs. aspect ratio linear regressions calculated for extant scorpions. The specimens’ calculated size-corrected residuals produced multiple improbable actual maximum pinch forces (n), negating the methodology’s reliability and effectiveness for fossil scorpions. Future research will transition to determining the relationship between log-transformed von Mises stress and log-transformed model chela volume in aquatic, littoral, and terrestrial fossil scorpions, based on studies from modern scorpions. Applications would include comparing the results between fossil and extant scorpions and between select fossil scorpions, especially those with interpreted disparate lifestyles and revising or supporting proposed semi-quantitative interpretations of their feeding and defensive strategies.