Local growth patterns in tibia associate with restricted external fundamental system in Cervus elaphus. Implications for life history strategies in fossil groups

Abstract

ABSTRACT The external fundamental system (EFS) is a band of slow-growing tissue, deposited in the periphery of the bone cortex of some tetrapod limb bones as a result of low bone growth rates. This structure has been commonly used as an indicator of maturity attainment, allowing researchers to infer life history traits (e.g. age at maturity, growth rates) in both fossil and extant taxa. However, some studies have recognised the absence of the EFS in the tibia of some vertebrate groups, thus raising concerns about the validity of this bone to reconstruct individual life history. This work analyses and describes for the first time the presence of the external fundamental system (EFS) in the tibia of red deer. Results show that the EFS seems to be strongly conditioned by local growth patterns, as its local deposition indicates. Finally, this study highlights the importance of tibia investigations to expand data of bone microstructure in Cervidae and illustrates that research on extant taxa are essential for deciphering growth dynamics and life history strategies of fossil organisms.