FIGURE 2 in Neoichnology of the eastern spadefoot toad, Scaphiopus holbrookii (Anura: Scaphiopodidae): criteria for recognizing anuran burrows in the fossil record

FIGURE 2. Quantitative properties of burrows. 1, Measured properties include maximum depth (D), tunnel and shaft width (w), height (h), and circumference (c), length (L), and slope (S). 2, Complexity (C) is the sum of the number of surface openings (e), segments (s), and chambers (h) of a burrow. 3, Tortuosity is a measure of the average sinuosity of all of the segments of a burrow system. The tortuosity of a single segment is calculated by dividing the length (u) by the straight-line distance (v). Modified from Hembree et al. (2012).