media captionThis CT scan discover the sixth "toe" - right here seen in dark green towards the back on the elephant's foot
A mysterious bony growth found in elephants' feet is in reality a 6th "toe", researchers report.

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For much more than 300 years, the framework has perplexed researchers, but this study says that it help to support elephants' colossal weight.


Fossils expose that this "pre-digit" evolved about 40 million year ago, in ~ a point when beforehand elephants came to be larger and more land-based.


Lead author Professor man Hutchinson, indigenous the UK's structure and motion activities at the imperial Veterinary College, said: "It's a cool secret that goes earlier to 1706, as soon as the very first elephant was dissected through a Scottish surgeon."


Many people, the said, assumed that the framework was a huge lump that cartilage, and also over the year its objective or absence of purpose has been debated.


"Anyone who has studied elephants' feet has wondered about it. They've thought: 'Huh, that's weird,' and also then moved on," that added.


But Prof Hutchinson and also colleagues used a mix of CT scans, histology, dissection and also electron microscopy to resolve the puzzle.


The researchers stated the framework was do of bone, back bone through a highly irregular and unusual arrangement.


But closer examination additionally revealed that it showed a strong similarity through an unusual bone the is uncovered in the prior feet the pandas.


This bone - i beg your pardon is not rather an extra digit, but does the task of one - help the panda come grip bamboo, and is dubbed the panda's "thumb" or "sixth finger". Moles too have a bone masquerading together an extra digit, which helps them to dig.


And now, the team claims that elephants deserve to be included to the perform of species for whom 5 fingers or toes room not fairly enough.


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Prof Hutchinson said: "It would have actually started out as a small nub in the tissue, which may have not also have to be bone originally - it could have been cartilage.


"A lot of animals have these structures, cartilaginous lumps, and they occasionally turn to bone with these really different attributes in part species."


Unlike pandas and moles, i m sorry only have actually the false number in your front feet, elephants have actually the bone in all 4 of their feet.


Their 5 conventional toes suggest forwards, offering elephants a tip-toed stance, yet the extra "toe" point out backwards into the heel pad, including extra support and helping the most heavy land animal to organize up its bulk.

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"We looked at early elephants and they had a different kind that foot, which appeared to it is in quite level footed and also didn't leave lot room for this structure underneath.


"The structure appeared to evolved approximately 40 million year ago, and it seems to have developed in concert with elephants acquiring bigger and much more terrestrial and also having upright feet, with a an ext tip-toed foot posture."


He said: "It is a an excellent example that how advancement tinkers and tweaks organization to administer different functions - in this instance to be co-opted come be used like a digit."