Reconstruction of the life history traits in the giant salamander Aviturus exsecratus (Caudata, Cryptobranchidae) from the Paleocene of Mongolia using zygapophyseal skeletochronology

Here we describe life history traits in the giant cryptobranchid salamander Aviturus exsecratus from the Paleocene of Mongolia using non-destructive approach for skeletochronological analysis based on the counting of cyclical growth rings on articular surfaces of zygapophyseal processes of vertebrae (= zygapophyseal skeletochronology). We found that Aviturus exsecratus had a similar time of the attainment of sexual maturity and decreasing of juvenile growth (5–8 years) and estimated body size at maturity (50–60% of the maximum size) as modern cryptobranchids. Maximum longevity estimated for A. exsecratus is about 25 years. A. exsecratus had a developmental trajectory similar to that of modern cryptobranchids and is not characterized by extended ontogeny. PIN: Paleontological Institute; Russian Academy of Sciences; Moscow; Russia.