You could have an alternative explanation: large animals invest lots of food energy in their offspring, and so the slimmest chance that a calf might not be dead is worth lots of effort. Say one in a thousand actually revive.

Here's an article about orcas: https://www.bbc.co.uk/news/science-environment-64559047

It seems that an orca invests so much in a son that it's like an all-or-nothing one way ticket to pass her genes on. (She might get second try later, but the probability is much lower.)

Indeed. The same goes for widows at funerals. I mean, has anyone ever dissected the brain of a grieving human and said “aha hah! Here it is!! The grief!”

> They exhibit behaviours that seem to defy alternative explanations

No, they really don't. The article says

> indicated an inherent, strong maternal attachment to the calf

Yeah, that's not grieving.