Methods for Estimating the Volume of the Tympanic Bulla in the big hairy armadillo Chaetophractus villosus (Mammalia, Xenarthra, Dasypodidae)

BASSO AP; SIDORKEWICJ, N.S; CASANAVE E.B

INTERNATIONAL JOURNAL OF MORPHOLOGY

Sociedad Chilena de Anatomía

Lugar: Temuco; Año: 2017 vol. 35 p. 128 - 132

0717-9367

SUMMARY: Two methods ofmeasurement of bullar dimensions (callipers and scaling from digital images)and subsequent application of four volume formulae (rectangular prism,cylinder, ellipse and elliptical cone) were tested to find the most appropriatenon-destructive method for estimating the bullar volume in Chaetophractus villosus. Material for the study consisted in clean adultskull (n=22). Real volume was obtained from latex casts of the tympanic bulla. Eachestimation was corrected by a factor based on the differences between theestimated and the real volumes. Highest accuracy (5-7% of underestimation) andprecision (coefficient of variation: 13.27%) were obtained from callipers and applicationof rectangular prism, cylinder and ellipse formulae. The correspondingcorrection factors were 0.31, 0.39 and 0.58, respectively.