How are elephants related to extinct mammoths and mastodons?

Elephants, mammoths, and mastodons are all members of the order Proboscidea, a group of mammals characterized by their unique tusks.1

Their relationships are defined by their taxonomic families:

• Elephants and Mammoths: Both belong to the family Elephantidae, the only surviving proboscidean family. Genetic and morphological studies indicate that Asian elephants are more closely related to mammoths than they are to African elephants. Asian elephants and mammoths diverged from a common ancestor, while African elephants split from that lineage earlier.1
• Mastodons: These animals are more distantly related to elephants and mammoths. They belong to a separate, distinct family known as Mammutidae.12

While these groups share common ancestry within the order Proboscidea—tracing back to early ancestors like the tapir-sized Moeritherium—they represent different evolutionary branches that diverged millions of years ago.13