Which arthropods have feet and why? Addressing an argument for aquatic fossil scorpions

Scorpions are the first arguably terrestrial animals identifiable in the fossil record, with important implications for arachnid evolution and terrestrial ecosystem development.  However, ongoing debate persists on whether some fossil scorpions from the Silurian and Devonian were, in fact, aquatic.  This study assesses the claim that a digitigrade (‘footless’) posture implies an aquatic habitat for early scorpions by evaluating the distribution of feet among ambulatory arthropods and how their presence correlates with factors including aquatic versus terrestrial habitat as well as body size, number of legs, cuticle mineralization, and time since terrestrialization.  The results demonstrate that these variables in isolation are poor predictors of leg posture, but become highly statistically significant in certain combinations.  However, with as many lineages diverging from the usual pattern of plantigrady as adhering to it, predictive power is weak.  Therefore, a..., , , # Data from: Which arthropods have feet and why? Addressing an argument for aquatic fossil scorpions

**Data_1_-_Body_Size_Measurements.csv**

Table containing measured body lengths and body widths (excluding appendages) of all taxa included in this study. Mean log body length and mean log body volume per leg were calculated and averaged over all taxa included in a given phylogenetic tree tip (tips correspond to the tree in files S4 and S5) for use in the phylogenetic general linear regression analysis.
Column descriptions:
Class - Taxonomic class of specimen.
Order - Taxonomic order of specimen.
Family - Taxonomic family of specimen; \"?\" if unidentified to family level.
Genus - Taxonomic genus of specimen; \"?\" if unidentified to genus level.
Species - Taxonomic species of specimen; \"?\" if unidentifed to species level.
Specimen number - An internal index used to order datapoints during figure generation.
Adult - Indicates whether specimen was mature; \"Y\" for yes (mature), \"N\" for no (i...,