A cattle rancher got the surprise of a lifetime when a calf with two heads was born on her farm.
Heather Herman, 30, made the discovery when inspecting the livestock at the family ranch in the US state of Montana.
The animal later died.
"I was doing one of my daily checks through our herd and noticed a cow alone so I went to check on her," said Heather.
"The calf was laying next to her but from a distance I could tell something wasn't quite right. I had very mixed reactions when I realised what was wrong.
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"You never want to lose a calf or have one of your animals suffer in any way. I honestly didn't want to look at it when I realized what it was."
Two-headed creatures are rare, especially among mammals, which have fewer offspring than reptiles and other animals.
They can occur when an embryo splits, but not completely, or when two separated embryos incompletely fuse.
Justin Adams of Monash University in Melbourne, Australia, said mammalian bodies tended to undertake a sort of genetic fact-checking that prevented such embryos implementing.
"If there are errors in development, there are miscarriages and spontaneous abortions," he said.
In this case, the calf made it full-term, though it did not survive beyond that.
Mrs Herman said the farm had been in the family for seven generations, but there was only one other incident like this they could recall.
"It's pretty rare, I've seen pictures before but have never seen it happen in person," she said.
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"Talking with my grandma she had seen a two-headed calf one other time. No one else I've talked to had ever seen it.
"We were amazed the mother was able to have the calf unassisted, we could have easily lost the cow. She was fine and didn't seem to have any issues calving.
"She was a mature cow who had had at least four normal calves before."
