Our analyses reveal the incomprehensible scale of the losses we face if we don't work harder to save global biodiversity.
Human activity - specifically late industrial capitalism - is putting more than 50 billion years of unique evolutionary history at risk, scientists have said.
Researchers have warned some of the world's most unique animals, such as the punk-haired Mary River turtle and the purple frog, are in danger of becoming extinct due to "unprecedented levels of human pressure" brought on by activities such as agricultural expansion.
The findings, published in the journal Nature Communications, are based on data gathered from 25,000 species, which assessed the extinction risk of terrestrial creatures such as amphibians, birds, mammals and reptiles.
The experts are calling for urgent action to protect one-of-a-kind animals, which are classed as evolutionarily distinct and globally endangered (Edge) species.
Dr James Rosindell, from Imperial College London, who is one of the study authors, said: "Our findings highlight the importance of acting urgently to conserve these extraordinary species and the remaining habitat that they occupy - in the face of intense human pressures."
A team of international researchers, which included experts from the Zoological Society of London (ZSL), Imperial College London and University of Oxford, looked at regions around the world with large concentrations of Edge species.
They found that many areas home to unique evolutionary history - such as the Caribbean, the Western Ghats of India, and large parts of south-east Asia - had "unprecedented levels" of human activity.
According to the researchers, the findings showed at least 50 billion collective years of evolutionary heritage to be under threat, almost four times longer than the age of the universe.
Lead author Rikki Gumbs, of Imperial College London, said: "Our analyses reveal the incomprehensible scale of the losses we face if we don't work harder to save global biodiversity - to put some of the numbers into perspective, reptiles alone stand to lose at least 13 billion years of unique evolutionary history, roughly the same number of years as have passed since the beginning of the entire universe."
Animals that are closely related, such as pangolins and tapirs, would be at greater risk of extinction, the researchers said, along with Edge species such as the Mary River turtle, named for the Mary River in Queensland, Australia, and the purple frog, found in the Western Ghats.
Other unique species such as the yellow-eyed nocturnal Aye-Aye lemur native to Madagascar, Chinese crocodile lizard, and the Shoebill - a large bird found in Africa's swamps and wetlands - could be also be lost to extinction, they added.
Mr Gumbs said: "These are some of the most incredible and overlooked animals on Planet Earth.
"From legless lizards and tiny blind snakes to pink worm-like amphibians called caecilians, we know precious little about these fascinating creatures, many of which may be sliding silently toward extinction."
Nilima Marshall is the PA science reporter.