Intraindividual variability of the histological, chronological and growth patterns in post-cranial elements of Liaoningvenator curriei (Paraves: Troodontidae)

A comprehensive description of the histology of 10 postcranial bones taken from Liaoningvenator curriei (holotype: DNHM D3012) is presented. Corresponding bone samples were sectioned to a thickness of 30 micrometres. The sections were then examined using transmitted and crossed-polarised light microscopes and photographed using an adapted camera and associated capture software. The study reveals that DNHM D3012 was a subadult approaching adulthood, certainly in its fifth year at the time of death. The comparisons of the different sections revealed that in L. curriei (DNHM D3012), the bones from forelimb elements grew faster than those from hind limb elements, this growth strategy likely being linked to its ground-dwelling locomotion. Interspecific comparisons with those other deinonychosaurs and basal avialans suggest that L. curriei (DNHM D3012) exhibits a transitive growth pattern between basalmost, smaller forms of troodontid, and more derived forms that got larger by extending the period of fast growth.