What we know now is that there are three species of modern elephants:
1. The Asian Elephant (Alphas maximus)
2. The African Elephant- forest dwellers (Loxodonta cyclotis)
3. The African Elephant- Savannah (Loxodonta africana)
Straight Tusked Elephant (Paleoxodon antiquus)
We also know that scientists believed the ancient predecessor, the Straight Tusked elephant (Paleoxodon antiquus) was the closest relative to the Asian elephant. But new research shows that the predecessor is actually more closely related to the African forest elephants. Even more new research of the mammoth genome reveals that mammoths and elephant species were known to interbreed in the past. This means the elephant family tree will need to be minimally altered.
What we know about the Straight Tusked elephant:
The Straight tusked elephant lived in European forests until 100,000 years ago.
Straight tusked elephants and mammoth species have interbred.
Straight tusked elephants have interbred with Asian elephants.
Straight tusked elephants represent the oldest whole genomes from a warm environment.
The greatest fascination about the elephant genome is that the Straight tusked elephant genome wasn't just sequenced, it was sequenced in such high quality, that each letter was sequenced on average
15 times, leaving many scientists in complete awe.
For more about the interbreeding of the mammoth and elephant: http://www.iflscience.com/plants-and-animals/scientists-successfully-insert-woolly-mammoth-dna-elephant-genome/