Occurrence of growth marks in the phalanges of the Indian Black Rat, Rattus Rattus (lannaeus, 1758)

Generally vertebrate age was determined by growth layers found in the cementum in the dentine. Age was determined for the first time by enumerating the number of growth marks present in the cross sections of phalanges of the Indian black rat (Rattusrattus) inhabiting southern India. Mid-diaphyseal sections of phalanges exhibited growth rings, each ring consisting of a broader growth zone and a chromophilic line of arrested growth (LAG). One to five growth marks were observed in specimens with different body sizes. There is a strong positive correlation between body size and LAGs, indicating that larger individuals have experienced greater number of growth cycles and hence may be older.