What did all types of Orca evolve from?

Question

There have been reports that it evolved from some deer-like creature that lived near the water.

Does anyone know which creature it was? Also, since there are different types of orca (transient, off-shore and resident), did they all evolve from this same creature?

Did this creature ever compete with the Megalodon for food?

Answer 1

There is only one type of orca aka the Killer whale.  It's actually an oversized dolphin, and it evolved from a very orca-like dolphin ancestor.

<<There have been reports that it evolved from some deer-like creature that lived near the water.>>

Perhaps you're muddling up orcas with whales and dolphins in general, and unnecessarily narrowing down the meaning of ungulate.   Molecular studies shows whales to be ungulates, with their nearest living relatives being hippos.  Deer are also ungualtes as well, but a long way removed from hippos and whales.

You're possibly trying to think of /Ambulocetus/, an early whale with four legs.

<<Did this creature ever compete with the Megalodon for food?>>

No.  It lived much earlier, was far smaller and lived in the coastal region of what's now Pakistan.

Answer 2

Orcas were once, believe it or not, were once land mammals called Pakicetus attoki.  They then evolved into water dwelling mammals called Rodhocetus balochistannsis.   These creatures then went throught other stages to become the creatures they are today.

Answer 3

They are closely related to dolphins and in the same group as porpoise and whales. The origin of the group goes back 50m years and hippos evolved from the same source.

Answer 4

All whales, dolphins and porpoises evolved from pakicetids, such as this sort of creature:

http://en.wikipedia.org/wiki/Image:Pakic...