University of Cape Town researchers challenge traditional bone growth aging methods in new study

University of Cape Town researchers find that crocodile bone rings do not always indicate age, impacting how scientists date dinosaurs and modern animals.

By: AXL Media

Published: Mar 5, 2026, 9:39 AM EST

Source: The information in this article was sourced from University of Cape Town - Faculty of Science

Microscopic analysis reveals inconsistencies in skeletal rings

Professor Chinsamy Turan and Dr. Maria Eugenia Pereyra conducted an investigation into the bone microstructure of young Nile crocodiles to test the reliability of skeletochronology. By examining bone slices from two year old specimens raised under identical conditions, the researchers observed distinct growth marks similar to tree rings. However, the analysis revealed a significantly higher number of rings than the actual age of the animals would suggest. Had the researchers relied solely on these marks, the crocodiles would have been incorrectly aged at between five and six years old.

Environmental factors influence biological growth markers

The study indicates that these skeletal marks are not strictly tied to yearly cycles but are instead highly flexible. The researchers suggest that the additional rings likely formed during favorable growing periods triggered by environmental variables. Factors such as extreme heat, dominance hierarchies, and competition for food appear to stimulate intermittent growth spurts that leave permanent traces in the dense, compact parts of the bone. This flexibility in growth rates mirrors observations in other vertebrates, including alligators and newts, which adapt their development based on external conditions.

Implications for dinosaur research and paleontology

These findings have significant consequences for the study of extinct species, particularly dinosaurs that are closely related to modern crocodiles. Paleontologists frequently use bone microstructure to estimate how long it took for dinosaurs to reach full maturity. Professor Chinsamy Turan and Dr. Pereyra caution that relying on derived growth curves may result in inaccurate age estimates for extinct vertebrates. They advise that growth marks in the outer part of the bone should be viewed as signs of intermittent growth rather than reliable indicators of annual passage.