Crocodiles Show 5‑6 Cycles Yearly, Doubt Dinosaur Ages
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- University of Cape Town – Researchers observed that juvenile caimans under one year displayed bone growth marks, contradicting the expectation that such marks only appear after a full year of growth.
- Le Bonheur Reptiles and Adventures – The team injected antibiotics into two‑year‑old Nile crocodiles at this South African farm, and the antibiotics later served as time‑stamped markers in the bone tissue.
- Nile crocodiles – Bone analysis revealed that the two‑year‑old individuals possessed five to six distinct growth cycles within a single year, far exceeding the presumed single annual cycle.
- Skeletochronology – Because extra growth marks can arise, applying this method to the studied crocodiles would overestimate their age, reversing the usual concern of underestimation.
- Dinosaur age estimates – The findings suggest that growth marks in dinosaur fossils, derived from crocodile and bird relatives, may also include “extra” rings, calling into question current reconstructions of dinosaur growth rates.
- Farm conditions – Even under optimal, resource‑rich farm conditions, the crocodiles formed additional growth marks, indicating that factors beyond food scarcity may drive the phenomenon.
Why it matters: Paleontologists who use skeletochronology to date dinosaur fossils now face a risk of over‑dating specimens, because extra growth marks observed in modern crocodiles may not reflect true age. This forces a reassessment of growth‑rate models and could alter interpretations of dinosaur life histories.
