The Kenyan paleoanthropologist was hailed by William as a "true visionary" after he spearheaded campaigns against the ivory trade to save the dwindling African elephant population.

In a tweet, the Duke of Cambridge said: "I was very sad to hear of Richard Leakey's death. He was an inspirational and courageous conservationist and I was privileged to meet him.

"He transformed the Kenyan Wildlife Service and valiantly spearheaded efforts to stop elephant poaching. Conservation has lost a true visionary."

Kenya's President Uhuru Kenyatta said Leakey had "served our country with distinction".

Leakey, the son of palaeontologists Louis and Mary Leakey, remained energetic into his 70s despite bouts of skin cancer and kidney and liver disease.

In the 1970s, he led expeditions that shed new light on the scientific understanding of human evolution, with the discovery of the skulls of Homo habilis (1.9 million years old) in 1972 and Homo erectus (1.6 million years old) in 1975.

It saw him feature on the cover of TIME magazine before his fame grew further when he fronted the BBC TV series The Making Of Mankind in 1981.

His most famous fossil find was yet to come, however, after his team uncovered a near-complete Homo erectus skeleton in 1984, which was nicknamed Turkana Boy and dated to about 1.5 million years ago.

In the late 1980s, Leakey emerged as one of the world's leading voices against the then-legal global ivory trade and he was appointed to lead Kenya's national wildlife agency in 1989.

That year he pioneered a publicity stunt which saw 12 tonnes of tusks set alight to make the point that they have no value once removed from elephants.

In 1993, a small plane piloted by Leakey crashed, crushing his lower legs, both of which were later amputated.

After speculation it was a murder attempt by enemies he made cracking down on poaching and corruption, he told The Financial Times in 2015 that "no one can say definitely whether or not it was sabotage".

"There were regular threats to me at the time and I lived with armed guards," Leakey told the newspaper.

"But I made the decision not to be a dramatist and say: 'They tried to kill me.' I chose to get on with life."

Leakey was a co-founder of the Safina Party in Kenya in 1995 and served as the country's head of civil service from July 1999 to March 2001, at a time when the then-president Daniel Arap Moi was under pressure to tackle corruption and other inefficiencies in government.

Paula Kahumbu, chief executive of conservation group WildlifeDirect, said Leakey had "a natural sense of leadership" that was "old-fashioned but straightforward".

"His memory was super sharp and his ability to hold many ideas in the air at once to find common threads was phenomenal. He will be dearly missed," she added.

Leakey was also a fellow of the UK-based Royal Society and an honorary fellow of the African Academy of Sciences.