The thickening of the cortical section of the bone and the compaction of bone in the terminal tail-spikes in old adults suggest that they were used as defence weapons, but not until an ontogenetically late stage. The development of the large axial channel in old adults from small canals in young adults, facilitated the further enlargement of the spikes by increasing the amount of nourishment supplied.
The thickening of bone tissue and compaction of tail-spikes in older individuals imply they were used as defensive instruments, but only at a later stage in their life cycle. The development of larger axial channels in elderly adults from smaller canals in younger adults enabled further growth of the spikes by providing additional nutrients.