Ethnographic observations of floor formation in an occupied and an abandoned Achuar jea dwelling structure are combined with contemporary taphonomic studies of swept and trampled surfaces. These studies suggest that refuse accumulation and incorporation are markedly different in food-preparation areas with ash deposits around fixed hearth features when compared to regularly trampled traffic areas of domestic earthen house floors. These points are examined in the horizontal and vertical analysis of highly fragmented bone remains in an Early Formative domestic house floor at the site of Real Alto, in the coastal lowlands of southwestern Ecuador. The food-preparation area of the Structure 1 house floor contained high concentrations of bone specimens characterized by their large size (over 25 mm), broad surface area, low bulk density, and greater total weight, vertically distributed throughout the ash matrix. The traffic area contained bone specimens characterized by their small size (under 25 mm), narrow surface area, high bulk density, and lower total weight, distributed unevenly in vertical profile. The horizontal distribution of fish bone only partially followed the observed pattern, as a proportionately greater amount of large fish bone was located in the traffic area. This analysis demonstrates the potential utility of bone refuse as a sensitive and reliable taphonomic indicator for inferential arguments regarding house-floor deposition.