Enlarge / Reddit user Kidipadeli75 spotted a fossilized hominin jawbone in his parents' new travertine kitchen tile. (credit: Reddit user Kidipadeli75)

Ah, Reddit! It's a constant source of amazing stories that sound too good to be true... and yet! The latest example comes to us from a user named Kidipadeli75, a dentist who visited his parents after the latter's kitchen renovation and noticed what appeared to be a human-like jawbone embedded in the new travertine tile. Naturally, he posted a photograph to Reddit seeking advice and input. And Reddit was happy to oblige.

User MAJOR_Blarg, for instance, is a dentist "with forensic odontology training" and offered the following:

While all old-world monkeys, apes, and hominids share the same dental formula, 2-1-2-3, and the individual molars and premolars can look similar, the specific spacing in the mandible itself is very specifically and characteristically human, or at least related and very recent hominid relative/ancestor. Most likely human given the success of the proliferation of H.s. and the (relatively) rapid formation of travertine.

Against modern Homo sapiens, which may not be entirely relevant, the morphology of the mandible is likely not northern European, but more similar to African, middle Eastern, mainland Asian.

Another user, deamatrona, who claims to hold an anthropology degree, also thought the dentition looked Asiatic, "which could be a significant find." The thread also drew the attention of John Hawks , an anthropologist at the University of Wisconsin–Madison and longtime science blogger who provided some valuable context on his own website. (Hawks has been involved with the team that discovered Homo naledi at the Rising Star cave system in 2013.)

Enlarge (credit: Sergey Krasovskiy )

Blue whales have been considered the largest creatures to ever live on Earth. With a maximum length of nearly 30 meters and weighing nearly 200 tons, they are the all-time undisputed heavyweight champions of the animal kingdom.

Now, digging on a beach in Somerset, UK, a team of British paleontologists found the remains of an ichthyosaur, a marine reptile that could give the whales some competition. “It is quite remarkable to think that gigantic, blue-whale-sized ichthyosaurs were swimming in the oceans around what was the UK during the Triassic Period,” said Dr Dean Lomax, a paleontologist at the University of Manchester who led the study.

Giant jawbones

Ichthyosaurs were found in the seas through much of the Mesozoic era, appearing as early as 250 million years ago. They had four limbs that looked like paddles, vertical tail fins that extended downward in most species, and generally looked like large, reptilian dolphins with elongated narrow jaws lined up with teeth. And some of them were really huge. The largest ichthyosaur skeleton so far was found in British Columbia, Canada, measured 21 meters, and belonged to a particularly massive ichthyosaur called Shonisaurus sikanniensis . But it seems they could get even larger than that.

Enlarge / Discovered in 1931, Tridentinosaurus antiquus has now been found to be, in part, a forgery. (credit: Valentina Rossi)

For more than 90 years, scientists have puzzled over an unusual 280 million-year-old reptilian fossil discovered in the Italian Alps. It's unusual because the skeleton is surrounded by a dark outline, long believed to be rarely preserved soft tissue. Alas, a fresh analysis employing a suite of cutting-edge techniques concluded that the dark outline is actually just bone-black paint. The fossil is a fake, according to a new paper published in the journal Paleontology.

An Italian engineer and museum employee named Gualtiero Adami found the fossil near the village of Piné. The fossil was a small lizard-like creature with a long neck and five-digit limbs. He turned it over to the local museum, and later that year, geologist Giorgio del Piaz announced the discovery of a new genus, dubbed Tridentinosaurus antiquus . The dark-colored body outline was presumed to be the remains of carbonized skin or flesh; fossilized plant material with carbonized leaf and shoot fragments were found in the same geographical area.

The specimen wasn't officially described scientifically until 1959 when Piero Leonardi declared it to be part of the Protorosauria group. He thought it was especially significant for understanding early reptile evolution because of the preservation of presumed soft tissue surrounding the skeletal remains. Some suggested that T. antiquus had been killed by a pyroclastic surge during a volcanic eruption, which would explain the carbonized skin since the intense heat would have burnt the outer layers almost instantly. It is also the oldest body fossil found in the Alps, at some 280 million years old.

Enlarge (credit: Henry Sharpe / AMNH)

In 2015, Deborah Shepherd returned to the site where she and other volunteers had worked on a public fossil dig with family members. That’s when she saw it: a fossil lying there, exposed on the surface. Most people would not have recognized it for what it was: It wasn’t a skull, a leg bone, or even a partial jaw. It was just a chunk of bone.

Shepherd immediately notified a park ranger. That ranger then notified the North Dakota Department of Mineral Resources. Her actions ultimately led to the discovery of what scientists say is not only a new species, but an entirely new genus of mosasaur, a giant marine predator from Late Cretaceous seas. Bite marks preserved on the fossil also suggest that it met its end at the hands—or rather teeth—of another mosasaur.

Meet Jorgie the mosasaur

The new mosasaur was described Monday in the Bulletin of the American Museum of Natural History. Jǫrmungandr walhallaensis , or "Jorgie" for short, is the name suggested by co-author Clint Boyd, and it’s steeped in Norse mythology. Jǫrmungandr is the name of a sea serpent who circles the world with its body, clasping its tail in its jaws.

Enlarge (credit: Jiri Svoboda)

Trilobites first appear early in the Cambrian and are one of the earliest examples of arthropods, the group that includes all insects. They flourished for over 100 million years, leaving fossils that are seemingly ubiquitous—we've described over 20,000 different trilobite species. That's over three times the number of mammalian species we're aware of.

Despite all those fossils, however, we've never found one with a meal inside it. We've been able to infer what some of them were likely to have been dining on based on their appearance and the ecosystems they were found in, but we haven't been able to establish what they ate with certainty. But today, researchers are describing an exquisitely preserved sample that includes several of the animal's last meals, which suggests that this particular animal was a bit like an aquatic vacuum cleaner.

The last several suppers

The fossil comes from shale deposits found in the Prague Basin of the Czech Republic. Those rocks date from the Ordovician, which came immediately after the Cambrian and lasted until about 450 million years ago. Mixed in among the layers of shale here are harder silicate nodules that have been termed "Rokycany Balls." When these nodules contain fossils, they tend to be well-preserved and provide three-dimensional details of the long-dead organisms.

Enlarge / The fish in question, with the ammonite located just below its spine. (credit: Cooper, et. al.)

Some extinct species left copious fossil remnants of their existence. Ammonites —an extinct type of cephalopod—are one such example. From the Devonian through the Paleocene, wherever ancient seas once covered Earth, one can usually find their coiled shells. So one more exquisitely preserved ammonite isn’t necessarily a big deal.

With the exception, perhaps, of one intact example found in the Posidonienschiefer Formation in Germany, where most ammonite shells are flattened and fragmentary. Now, decades after its original discovery, scientists have taken a more careful look at the well-preserved ammonite and the fossil fish it was seemingly nestled against. What they found surprised them: the fish had actually swallowed the large ammonite—something we’ve never seen before, even in fossils of much larger marine species that we know attempted to feed on ammonites.

It didn’t work out well for the fish. The size of the ammonite may have caused the fish to drown, or it may have blocked its digestive tract, causing internal bleeding. Drifting down to the seafloor, the fish was eventually buried and fossilized, preserving that ammonite—along with information about the ecosystem it and the fish inhabited—for over 170 million years.