Skeletochronological analysis was used to compare stained and unstained cross sections of humeri from Kemp's ridley (Lepidochelys kempii) and loggerhead (Caretta caretta) sea turtles to determine if the 2 histological techniques yielded an equal number of visible lines of arrested growth (LAGs). Stained sections viewed at high magnification under a compound microscope revealed the presence of closely spaced and splitting LAGs, resulting in a greater number of individual LAG counts for these sections when compared to unstained and stained sections viewed at a lower magnification under a dissecting microscope. Prior studies have shown that some of these closely spaced LAGs are annual, and therefore the inability to detect such marks could result in a downward bias in age estimates.