A group of scientists has published a report saying there are two different species of African elephant.
The report says the species have been different for over three million years and that one type of African elephant is around twice as heavy as the other.
The notion that there are two species of African elephant first emerged about a decade ago.
The animals are very different in size; the savannah or bush elephants stand about a metre taller, and weigh twice as much as their forest-dwelling cousins. But whether this means they are truly different species hasn't been clear.
Now a team of researchers from the UK, Germany and the US, say they've resolved the issue. Writing in the journal Public Library of Science Biology, they say their analysis proves the existence of two distinct species.
This has been a hotly-disputed question and it's entirely possible that other researchers will challenge the claim.
If it is confirmed, there may be important implications for conservation. Forest elephants are mainly found in Central and Western Africa, the areas where poaching and ivory smuggling are most serious. There, populations are declining. Further south, in the domain of the savannah elephants, the animals are thriving. Conservationists say proving the species split could help concentrate attention where it's most needed, on nations that have done little to crack down on poachers and smugglers.