
TY  - JOUR
A1  - De Miguel, C. 
A1  - Henneberg, M. 
T1  - Encephalization of The Koala, Phascolarctos cinereus.
JF  - Australian Mammalogy
JO  - Aust. Mammalogy
Y1  - 1998
VL  - 20
IS  - 3
SP  - 315
EP  - 320
KW  - 
UR  - https://doi.org/10.1071/AM98315 
N2  - Brain size relative to body size is considered to be an indicator of variously defined &apos;braininess&apos; (=encephalization). Indices of encephalization are based on the ratio of the animal&apos;s actual brain size to its expected brain size calculated from an allometric equation derived from a brain size I body weight relationship in a series of taxa Freshly collected data on brain and body weights of 27 adult koalas (Phascolarctos cinereus) from South Australia are analysed here. Sex- averaged brain weight in this sample is 19.2 g and body weight is 8.0 kg. General equations for mammals produce encephalization values for the koala well below the mammalian average: EQ=38.9% ac- cording to Jerison&apos;s equation (1973), EQ= 49.7% applying Eisenberg&apos;s equation (1981) and EQ= 35.3% using Martin&apos;s equation (1990). When a &apos;basal&apos; insectivore line is used, the koala appears to be progressive: IP =155.9% according to Stephan&apos;s equation (1972) and ICC= 131.7% using Martin&apos;s equation (1990). Use of &apos;basal&apos; marsupial lines also indicates progressive encephalization of the koala: Pl=l l6.5% according to Pirlot&apos;s equation (1981}, E=108.4% following Nelson and Stephan&apos;s equation (1982) and E=107.9% using Haight and Nelson&apos;s equation (1987). These new results are clearly higher than the indices for the koala reported earlier by other authors (Nelson and Stephan 1982; Haight and Nelson 1987). It follows that choice of samples and equations influences conclusions regarding encephalization of a species. 
ER  -

