A Skeletochronological Study to Determine the Age of the Ringed Salamander (Ambystoma Annulatum)

Date of Graduation

Spring 1995


Master of Science in Biology



Committee Chair

Robert Wilkinson


In the fall of 1993 and 1994 in Stone County, Missouri, 202 sexually mature ringed salamanders (Ambystoma Annulatum) were caught in a semi-permanent pond by using pit-fall traps and drift fence. The sex ratio strongly deviated from a 1:1 ration and approached 3:1 in favor of males. The average snout-vent lengths were significantly higher (p<0.0001) in females (91.58mm, Std=7.16mm) than in males (83.66mm, Std=7.33mm). Age was determined by taking cross-sections of phalanges and counting the number of resting lines present. The average number of resting lines present was 9.12 (Std=2.02) in females and 6.65 (Std=1.88) in males. The data suggest that the approximate age of sexual maturity is five to six years (SVL>70mm) in females and three to four years (SVL>61mm) in males. The oldest individual was 15 years. Regression analysis showed a general relationship between SVL size and age for both males (p<0.0001) and females (p<0.0001). Due to large variation in size at a given age, a precise estimation of age is not possible for an individual when only size is known. (male: r²=0.427 ; female: r²=0.304).

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© David Taylor Winter