At www.irishtimes.com/news/ireland/irish-news/antlers-and-horse-bones-datin… …. red deer antlers shed by young animals and horse bones dating back to between 430 and 548AD appear to suggest pagan practises were still in vogue even after the introduction of Christianity to Ireland by St Patrick. I suppose that is one way of looking at it if you suppose there is a ritual angle. However, the author does not pick up the fact that the low growth tree ring events between 536-45AD are smack bang in the mix of the C14 margins. It is just as likely that cold weather had affected crop yields and people were forced to eat their horses and donkeys in order to survive. It doesn't necessarily mean a revertion to a pagan rite – although the nature of the low growth tree ring event may have a cosmic connection (but volcanoes are the usual interpretation).
What is more interesting than some antlers and horse bones is what is said by a geologist who was consulted on the find. It seems that several thousand years ago Galway Bay was once an area of lagoons and forests before sea level changes drowned the bay. He goes on to say 'significant environmental change' may also have occurred as recently as 1500 years ago, having examined the area where the antlers and bones were embedded. This, it seems to me, is vindication of Steve Mitchell's claim that sea levels around Britain changed dramatically in the post-Roman period. They went up and a few centuries later, subsided again. He came to this conclusion from the study of beach marks in Scotland – and now we have the same thing in western Ireland.
The geologist speculates the site in the bay may have been protected by glacial debris and the remains of drumlins. This suggests there might also be a more extensive drumlin field further out in the bay – which was breached and flooded.