Overview
- The PeerJ study analyzes transverse femur and tibia sections from 17 Tyrannosaurus specimens, the most comprehensive histological dataset yet assembled for the species complex.
- Including faint annual bands visible only under cross-polarized light adds missed growth marks, producing slower growth trajectories, later asymptotic size around 35–40 years, and larger typical adult masses reported near 8–8.8 tonnes.
- A novel statistical approach stitches overlapping partial records across individuals and is the first to estimate the earliest preserved growth mark while fitting sigmoidal growth curves with confidence bands.
- Two well-known specimens, “Jane” and “Petey,” show growth curves statistically incompatible with the main series, sustaining debate over whether some small tyrannosaurs represent different species such as Nanotyrannus or reflect other biological factors.
- The authors argue common skeletochronology protocols need revision and emphasize that scarce juvenile fossils and unresolved links between growth-curve inflection points and sexual maturity call for further sampling and replication.