Jawdropping discovery: Remains of extinct human species that died thousands of years ago found in kitchen floor tiles

A dentist caught a huge surprise when he visited his parents' house and spotted a familiar bit of anatomy embedded into the corridor of their newly renovated home.

The freshly laid tile appeared to contain a human jawbone, just inside the threshold that leads out to the terrace, according to a post on Reddit where he shared the find.

Reddit is rife with fake posts, but multiple experts confirmed to DailyMail.com that this really does appear to be a jawbone, and that it probably belonged to either a modern human (Homo sapiens) or, more likely, an extinct hominin like Homo erectus or a Neanderthal.

And if the fossil belonged to one of these ancient human ancestors, it is anywhere from 24 thousand to 1.9 million years old.

A Reddit user posted this photo of a jawbone found in his parent's home. It was embedded 

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Redditor Kidipadeli75, who said he is a dentist, posted a photo of the tile in the r/fossils forum.

The tiles in question are made of travertine, a calcium-rich limestone that is often mined and cut for tile. 

'While fossils are often found in travertine, hominin fossils are much less common,' archaeologist Kristina Killgrove told DailyMail.com. 'This one is definitely a hominin's lower jaw bone, cut transversely somewhere through the middle.'

As can be seen in the photo, the jawbone was cut at an angle. Some cross sections of teeth remain on one side, while the teeth have been cut out of the other side, exposing the fossilized inside of the mandible.

'I'm not at all surprised that there are bones embedded into this type of stone,' Angelique Corthals, associate professor of forensic anthropology at John Jay College of Criminal Justice, told DailyMail.com.

'It's pretty common. The uncommon thing is to be that lucky that you find the embedded hominin jaw,' she said.

A common and desirable material for tiles, travertine is cheaper than marble, and its veins of calcite crystals give it an interesting appearance. 

It forms near natural springs, including Mammoth Springs in Yellowstone National Park.

At these springs, many large and small animals live and die. And when they die, their remains end up trapped in the sedimentary rock until dug up to tile someone's home.

In this case they ended up in the home of Kidipadeli75's parents, who had not noticed the jawbone until he pointed it out. 

'They chose 'second choice' travertine which means with more flaws than 1st choice so it would be cheaper and less slippery,' Kidipadeli75 wrote.

Many people must have overlooked the jawbone for it to end up in the tiles of a newly renovated home, said Corthals.

When workers cut the stone at the quarry, and when retailers cut it up for tiles, nobody tends to pay attention to fine details, she said. 'The retailers of the stone are mostly concerned with the integrity and the solidity of the stone, and really they don't care what's in it.'

In fact, some architects seek out travertine stone for tiles because they tend to contain fossils - but these mostly tend to be leaves and insects, said Corthals, not hominins.

The fossilized jawbone may have belonged to a member of the ancient human ancestor species Homo erectus, who lived between 1.9 million and 108 thousand years ago.

Travertine is a common and desirable material for home tiles. It is cheaper than marble, and its veins of calcite crystals give it an interesting appearance.

Neither Killgrove nor Corthals could say for sure what kind of hominin species the jaw belonged to, but Corthals had some ideas.

'The mandible is fairly narrow. It could be a human, but it looks more like a hominin,' she said.

'There's been fossils of Homo erectus and Homo heidelbergensis excavated from this type of stone before. It could be Neanderthals, it could be anything. Any of the hominins,' Corthals added.

The tile was quarried in Turkey, Kidipadeli75 wrote, and Corthals confirmed that travertine quarries in Turkey have been the site of multiple hominin finds.

Because of the angle the jawbone was cut to make the tile, it may also be difficult for a paleontologist to identify who the tile came from.

Some clues are there, though, Corthals said.

She pointed out the alveolar process, the thick ridge of bone that holds the tooth sockets.

At Mammoth Springs in Yellowstone National Park, you can see travertine being formed in real time, as calcium-rich water precipitates its minerals onto the surface.

The jawbone in the travertine tile, shown here with a banana for scale. The redditor's parents did not notice it until he pointed it out.

In modern humans, this section of bone is not very long front to back. But in this jawbone, it has a large amount of material behind the front teeth.

This thickness is more characteristic of Homo erectus mandible anatomy.

'My money is on Homo erectus,' Corthals said. 'There is much more space there than on Homo sapiens.'

The overall width of the mandible, too, looks more like Homo erectus than Homo sapiens, she added.

If the jawbone belonged to a Neanderthal, it could be between 200 thousand and 24 thousand years old. And if it belonged to a member of Homo erectus, it could be between 1.9 million and 108 thousand years old.

Jawbones tend to be relatively fragile, Corthals pointed out, so the fact that it's intact suggests it was probably fossilized before it got embedded into the travertine.

And since fossilization can take a long time, the jawbone is also probably extremely old, she said, making it unlikely that it belonged to a modern human.

So this newly tiled home is probably not a crime scene, fortunately. But it is quite a find.