Of the forensic studies of the effect of passing lawn mowers over skeletal remains, this is the most recent:
“Lemonade from Lemons: The Taphonomic Effect of Lawn Mowers on Skeletal Remains,” D.C. Martin, Gretchen R. Dabbs [pictured here], Lindsey G. Roberts, Journal of Forensic Sciences, epub July 3, 2013. (Thanks to investigator Rolf Zwaan for bringing this to our attention.) The authors, at Southern Illinois University, report:
“This study provides a descriptive analysis of the taphonomic changes produced by passing over skeletonized remains (n = 4, Sus scrofa) with three common lawn mowers. Two skeletons were mowed over with a riding lawn mower set at multiple blade heights (10.16, 7.62, 5.08 cm) and one each with a rotary mower (9.53, 6.35 cm) and a mulching mower (6.35 cm). Results show that different types of common lawn mowers will produce different patterns of bone dispersal and fragmentation rates. Overall, skeletal elements projecting upward from the surface frequently exhibited a sheared morphology characterized by a smooth, flat, cut surface (7.0-7.6% of elements). The push mowers yielded a higher frequency of undamaged bone than the riding mower (54.8-61.2% vs. 17.7%), and the riding mower created more catastrophic damage to skeletal elements. Additionally, each mower produced a distinct dispersal pattern of skeletal fragments. The dispersal patterns have been identified as “bull’s-eye” (riding), circular (mulching), and discontinuous rectangle (rotary).”
Some details from the paper:
BONUS (unrelated): Video of mowing with a murder of crows: