Its appearance told one story; its DNA tells another.
asserted
DNA → tell → another
For decades, the extinct Miracinonyx trumani was known as the “American cheetah” because its long legs, slender body and adaptations for speed made it look remarkably similar to Africa’s modern cheetahs.
asserted
it → know → cheetahs
But a new genetic
study has overturned that long-held picture.
asserted
study → overturn → picture
Published in Current Biology, the research used ancient DNA from fossil remains to show that M. trumani was actually a close relative of the modern puma, with the two lineages diverging about 2.6 million years ago.
asserted
lineages → publish → puma
The study also reveals that some of these supposedly cheetah-like cats had a surprising diet, with northern populations apparently eating fish in the Arctic.
asserted
populations → reveal → Arctic
The “American cheetah” was not actually a cheetah
Miracinonyx trumani lived across parts of North America during the Pleistocene, with evidence placing the species from roughly 2.5 million to 16,000 years ago.
asserted
evidence → live → million
Fossils showed that it had a body built for running, including long limbs and a relatively slender frame.
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it → show → limbs
Those characteristics led scientists to compare it with the modern cheetah, and the nickname “American cheetah” became widely used.
asserted
nickname → lead → cheetah
The new genetic evidence, however, tells a different evolutionary story.
asserted
evidence → tell → story
Researchers analysed nuclear DNA from four M. trumani fossils, including specimens from Wyoming and the Yukon in northwestern Canada.
asserted
Researchers → analyse → Canada
By comparing their genomes with those of living and extinct cats, they found that M. trumani was a sister species of the modern puma, rather than a close relative of the cheetah.
asserted
trumani → compare → cheetah
The two lineages separated roughly 2.6 million years ago.
asserted
lineages → separate → ?
That means the similarities between the extinct cat and today's cheetahs were not evidence of close ancestry.
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similarities → mean → ancestry
Instead, they were an example of convergent evolution, in which unrelated animals independently develop similar physical characteristics because they face similar environmental pressures.
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they → develop → pressures
Why did it look so much like a cheetah?
asserted
it → look → cheetah
The resemblance makes sense when the animal's lifestyle is considered.
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lifestyle → make → sense
Both M. trumani and modern cheetahs evolved body shapes suited to fast movement.
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trumani → evolve → movement
Long limbs and a lightweight build would have helped M. trumani pursue prey across open landscapes.
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trumani → help → landscapes
But appearance can sometimes give scientists an incomplete picture of an extinct animal.
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appearance → give → animal
Without genetic evidence, it was difficult to determine whether the American cat had inherited its body shape from a cheetah-like ancestor or had independently evolved similar features.
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cat → determine → features
The DNA has now provided a clearer answer.
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DNA → provide → answer
According to the researchers, the name “American cheetah” can therefore be misleading because it suggests both a close genetic relationship and a specialised hunting lifestyle similar to that of modern cheetahs.
uncertain
it → accord → cheetahs
Neither assumption is supported by the new evidence.
asserted
assumption → support → evidence
Ancient DNA reveals a surprising Arctic diet
The genetic discovery was not the only surprise.
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discovery → reveal → diet
The researchers also examined stable carbon and nitrogen isotopes preserved in the fossils to reconstruct what the animals ate.
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animals → examine → what
The results suggested that M. trumani was not necessarily a specialised hunter of terrestrial herbivores throughout its range.
uncertain
trumani → suggest → range
The northern specimens, recovered from the Yukon, showed chemical signatures consistent with a diet rich in aquatic animals.
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specimens → recover → animals
Researchers believe these cats may have eaten fish, potentially including salmon.
uncertain
cats → believe → salmon
They may have caught fish themselves, scavenged fish after spawning or used both strategies.
uncertain
They → catch → strategies
The available evidence cannot determine exactly how the animals obtained their aquatic food.
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animals → determine → food
That finding is particularly striking because the northern M. trumani populations lived in an environment very different from the grasslands where their southern counterparts hunted.
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counterparts → live → grasslands
The Wyoming specimen, by comparison, had isotope signatures more consistent with a predator feeding largely on terrestrial herbivores.
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specimen → have → herbivores
This suggests that the species could adjust its diet substantially depending on where it lived.
uncertain
it → suggest → diet
The cat's range was larger than scientists realised
The Yukon fossils also expand the known geographical range of M. trumani by about 20 degrees of latitude farther north than previously recognised.
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fossils → realise → latitude
The findings indicate that the species was capable of surviving in remarkably different environments, from temperate parts of North America to the Arctic.
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species → indicate → Arctic
Researchers say this flexibility resembles the adaptability seen in modern pumas, which occupy a wide range of habitats and consume many types of prey.
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which → say → prey
Genetic evidence also revealed changes that may have helped northern populations cope with extreme seasonal light conditions.
uncertain
populations → reveal → conditions
Researchers identified loss-of-function mutations in genes involved in regulating circadian rhythms, potentially reflecting adaptation to the very long periods of daylight and darkness found at high latitudes.
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Researchers → identify → latitudes
Why did the American cheetah disappear?
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cheetah → disappear → ?
The study also offers clues about the species' eventual extinction.
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study → offer → extinction
…and 8 more, not listed.
