Bone histology showed that "Gargantuavis" had a rapid early growth followed by an extended period (of at least 10 years) of slow cyclical growth before to attain skeletal maturity. A similar pattern is known in extinct dinornithiformes and in the extant kiwi, which are also insular birds. The titanosaur "Ampelosaurus", found together with "Gargantuavis" in the Bellevue site, shows also a reduction in its growth rate, possibly linked to some environmental pressure like periodic food shortages. This is supported by sedimentological and mineralogical studies which indicate episodes of semi-arid and strongly seasonal climate during the Late Cretaceous in Southern France.