Is this a dog mummy?
This ceramic coffin belonged to an Ibis, a type of bird that ancient Egyptians associated with the god of wisdom, Thoth.
Did the animals die of natural causes before mummification? Or were they killed for sacrifice?
It depends on the animal. We know that ibises were raised in farms to be killed and mummified, because there was such a demand to send messages to the god Thoth and because ibises could be raised in captivity. On the other hand, animals like falcons were harder to raise for this purpose, so some probably died of natural causes.
How did the museum acquire these mummies?
We acquired many of them from the New York Historical Society which acquired them from other collectors. Others, like this ceramic coffin, were acquired directly from excavators working for the Egypt Exploration Society a British organization that conducts scientific excavations.