6 Rare Fossils That Were Hidden In Plain Sight

In December 2024, researchers published a paper in Paelontologia Electronica detailing an incredible fossil discovery — the 45-million-year-old skull of a Diatryma, a genus of giant flightless bird. Only, they didn't unearth it from the ground. Instead, the fossil had been hiding right under their noses in a museum collection in Germany for decades. Originally uncovered in the 1950s in Germany's Geiseltal region, the skull had been initially misattributed to an ancestor of a crocodile.

Michael Stache, a geological preparator at Martin Luther University's Central Repository of Natural Science Collections and co-author of the paper, randomly stumbled across the fossil a few years ago. Realizing a mistake had been made, he began restoring the fossil, employing help from study co-author and Senckenberg Research Institute researcher Gerald Mayr. Mayr identified the fossil as belonging to Diatryma — whose only other known skull sits in the American Museum of Natural History in New York. Diatryma was a massive bird species, similar to the more well-known Phorusrhacidae, a classification of a large terror bird that was taller than a basketball player. The two differ in that Diatryma was a herbivore, whereas Phorusrhacidae was carnivorous.

As Mayr said of the discovery in a press release, "This shows once again that many of the most interesting discoveries in palaeontology occur in museum collections. Just a few years ago, nobody would have thought that the Geiseltal Collection would contain such surprises." Diatryma's appearance underscores a larger trend in the field. In recent years, scientists have increasingly begun stumbling upon discoveries in the fossil record hiding in plain sight. These findings remind us of the importance of fossils and that our understanding of natural history is constantly adapting to new knowledge — sometimes drastically. Here are five more rare fossils that were hiding in the open.

Soft tissue rarely gets preserved in the fossil record, which is one reason why locations like the Burgess Shale, which contains fossils of soft-bodied animals from the Cambrian explosion some 545 million years ago, are so important. In 2023, a study published in Papers in Paleontology revealed that a collection of 500-million-year-old fossils from the Mazon Creek fossil deposits in northern Illinois previously thought to be the remains of jellyfish were actually sea anemones. And the way scientists realized this? By flipping the fossils upside down.

"Anemones are basically flipped jellyfish," study lead author and University of Illinois Chicago Earth and Environmental Sciences professor Roy Plotnick said in a press release. "This study demonstrates how a simple shift of a mental image can lead to new ideas and interpretations." Mazon Creek is a well-known site with exceptional fossil preservation owing to an ancient delta having buried the marine animals that lived there in sediment. The anemone fossils had been misidentified in 1979 when Merrill Foster, a Bradley University professor, conducted the first extensive study of the once gelatinous creatures. Labeling them the Essexella asherae jellyfish, Foster claimed they featured a curtain that hung from the top bell of the jellyfish that surrounded its tentacles. 

Plotnick and his team put this claim under scrutiny when they examined thousands of museum fossils, quickly realizing that, whatever they were, they weren't jellyfish. "Although most of these fossils are preserved as decomposing blobs that look like a piece of used gum on the sidewalk, some specimens are so superbly preserved that we can even see the muscles that the anemones used to bend and contract their bodies," study co-author and Curator of Geology and Paleontology at Manitoba Museum Graham Young said in a press release.

For 30 years, pterosaur fossils discovered in Alberta, Canada, were mistakenly identified as belonging to Quetzalcoatlus, one of the largest flying reptiles ever known. However, a 2019 study published in the Journal of Vertebrate Paleontology proved that the remains consisted of an entirely new species of pterosaur. Named Cryodrakon boreas — Greek for "Frozen Dragon of the North Wind" — this prehistoric giant had a wingspan of up to 30 feet and stood as tall as a young giraffe. Researchers say Cryodrakon likely had a bizarre and terrifying appearance, with a slender head that was three times the length of its body.

Paleontologist Michael Habib, one of the paper's co-authors, suspected that the "Quetzalcoatlus" fossil was not quite what it seemed when he saw it for the first time several years ago. With the help of David Hone, a pterosaur taxonomy specialist, the two realized that the 30-year-old specimen was likely a new species. "This type of pterosaur (azhdarchids) is quite rare," Habib told Sci.News. Whereas most azhdarchids are represented by just a few bones, "Our new species is represented by a partial skeleton," he says. "This tells us a great deal about the anatomy of these large flyers, how they flew, and how they lived."

Misidentification is not uncommon in paleontology, particularly in pterosaurs, whose delicate bones often fragment before fossilizing. Another such case emerged in 2020, when fossils previously thought to be shark fin spines were reexamined and identified as jaw fragments from an ancient, toothless pterosaur. The fossils, stored in the Sedgwick Museum of Cambridge, actually belong to another azhdarchid pterosaur, a group known for its long, stork-like necks. Published in the Proceedings of the Geologists' Association, the study notes that the skeletal fragment indicates the new mystery species' existence but is not enough to definitively assign it a name.

For decades, scientists working on Barro Colorado Island, the largest land mass in the Panama Canal channel, had no idea they were walking over a 22-million-year-old fossilized mangrove forest. But in 2018, researchers on a geological expedition with the Smithsonian Tropical Research Institute (STRI) stumbled on hundreds of fossilized wood stumps exposed along a small creek. Upon analyzing them, 50 of the specimens turned out to belong to an entirely unknown species, whose existence the research team published in the journal Paleogeography, Paleoclimatology, Paleoecology in March 2024. Dubbed Sonneratioxylon barrocoloradoensis, the mangrove trees are remarkably well-preserved thanks to a volcanic eruption that buried the forest millions of years ago.

"We never imagined that fossil wood would be in BCI," geologist and study co-author Carlos Jaramillo told Live Science about the discovery. "[They] are hard to tell apart from any other decaying tree in the forest."

The newly discovered mangrove tree has only one living relative in Southeast Asia, Sonneratia, suggesting that the newfound species may have been found around the tropics in prehistoric times. Sample analysis also revealed that the species was taller than present-day mangrove trees thanks to an abundance of carbon dioxide in the atmosphere at the time. "Although there are many fossilized woods described from Panama, this is the first record for this genus," study lead author Camila Martínez told STRI. "This might be because mangroves occupy very reduced and specific spaces and conditions. This discovery helps us understand the type of vegetation that existed in areas that had just emerged from the ocean." Such findings and the insights they give researchers are a big part of the reason why scientists study fossils at all. 

In 2008, nine-year-old Matthew Berger, son of paleoanthropologist Lee Berger, came across a fossilized clavicle protruding from a rock outside of South Africa's Malapa Cave in the Cradle of Humankind Heritage Site. The chance finding led to the unearthing of a new hominin species, Australopithecus sediba, which roamed the Earth roughly 2 million years ago. That clavicle belonged to a juvenile male, with further examination of the cave revealing more remains from the same specimen, along with a fossilized female of the same species.  The discovery was profound — the line of ancient human evolution had found a new member, one that blended primitive and human-like features.

But happenstance would play another role in A. sediba's story. Just four years later, Justin Mukanku, a student at the Wits Institute for Human Evolution in Johannesburg, South Africa, noticed a fossilized tooth lodged in a large rock that had been sitting in the institute's lab for years. A CT scan of the rock later showed that it contained not just a tooth, but thigh bones, ribs, vertebrae, and jaw parts, which scientists later showed to be missing pieces of the initial 2008 skeletal find.

Subsequent fossil discoveries have given researchers a window into how our ancient human relatives moved. A. sediba, it seems, had adaptations for both bipedalism and climbing and swinging in the trees, making it a transitional link in the human evolutionary record. And while a 2019 study has since called into question the claim that A. sediba is a direct ancestor of Homo sapiens, scientists would not be able to have that debate without the 2012 chance finding that helped fill out the skeletal picture for A. sediba in the first place.