Imagine you’re a fossil.

You were lucky enough to die in a place  that was conducive to making fossils. Then you were buried and managed to  persevere for thousands or millions   of years without being broken  or crumbled or washed away.

After all of that, you get discovered by  a researcher and you’re set for a life of   luxury in a museum, where you’ll be cared  for in a perfectly controlled environment. And then you get lost in the mail. Unfortunately, it’s not an uncommon story.

Every so often, disaster strikes, and precious   artifacts from the ancient past are  lost, for a whole range of reasons. But that doesn’t mean that we  can’t still learn from them. So here are five of the most  important fossils that have   gone missing over the years, plus  one that made it safely back home. [♪ INTRO] In 1927, archaeologists discovered  a hominin tooth in Zhoukoudian,   an area about 40 kilometers outside of Beijing.

Two years later, they discovered  a skullcap at the same site. Its sloped forehead and prominent  brow ridge told researchers it was   from the species Homo erectus,  one of our evolutionary cousins. Excavations of the site continued until  1937, turning up fossils from at least   40 different individuals, all dating to  between 770,000 and 230,000 years ago.

This particular brand of Homo erectus  came to be known as Peking Man,   for the city that we now call Beijing. The fossils were studied at  Peking Union Medical College. But as you may know, that wasn’t the safest  place to be in the late ‘30s and early ‘40s.

Japan had captured the city in 1937, and by 1941,   they were getting ready to get the US  involved in the war in the Pacific. In an attempt to save the precious Peking  Man fossils from being damaged in the war,   they were smuggled out of  China and sent to the US... Or at least, they were supposed to be.

See, they never arrived. There’s been plenty of speculation  over the decades about where they went,   whether it was a train heist  or just a bureaucratic mistake. Whatever happened, the end result was the same.

An entire decade’s worth of  precious hominin fossils vanished. Luckily, the research team had  made plaster casts of the fossils,   so we do actually know what these  missing fossils looked like. But with new research methods  like isotope analysis,   there’s plenty that we can’t  know without the real fossils.

Although, this may not be the end of the story. In 2010, we got a new clue, thanks to the son of a US Marine who had been stationed in China in 1947. He said his father told him that when  the Marines had been digging foxholes,   one night, they dug up a box of bones.

They were, understandably, freaked out, so they  just filled in the hole and dug another one. But naturally, anthropologists thought  that this shipping crate full of bones   could be the missing fossils,  so anthropologists went to the   site of the military base that the guy  had been stationed at to poke around. But when they got there, they discovered  that it had been turned into… a parking lot.

Since suspicion of fossils isn’t good enough  grounds to demolish an entire parking lot,   the recovery mission pretty much stopped there. However, local officials have promised  that if the area is ever redeveloped,   they’ll keep their eye out for any  boxes containing ancient hominins. Our next missing fossil was  also buried, but not by humans.

In 1989, a dig in Alberta,  Canada unearthed the cast of   a single footprint that appeared to  belong to a juvenile tyrannosaurid. The footprint shows that this dino’s toe was bent  underneath the foot, and evidence of injuries like   that can be hard to find in the fossil record,  which made this a pretty special pawprint. Unfortunately, when researchers returned the next  year to try to excavate it, they couldn’t find it.

Turns out that the area had  experienced a rockslide,   and the unique track was now  buried under layers of rubble. So scientists have to be content with  photos that were taken of the track,   at least until it’s re-revealed  in a couple million years. Easy come, easy go.

This next fossil loss stings a  little more than some others,   not just because of what went  missing, but also where it came from. Some locations just don’t lend  themselves to skeletal fossils,   like the Connecticut River  Valley of the American Northeast. Which is why it was exciting when a complete   dinosaur skeleton was discovered near  Mount Holyoke College in Massachusetts.

This dinosaur was just a little  guy, about 18 centimeters long. It was also bipedal and carnivorous. The fossils were embedded in a boulder, which  is where the chair of Mount Holyoke’s geology   department, Mignon Talbot, spotted it  while out for a walk way back in 1910.

She named her new fossil Podokesaurus holyokensis. Professor Talbot was the first woman to  find and name a new dinosaur species,   making this fossil important for  paleontology and for feminism. Talbot was big on curatorial work,   and helped Mount Holyoke acquire a  massive collection of specimens, casts,   and fossils that rivaled the collections  at bigger schools like Harvard and Yale.

But then, in 1917, disaster struck. The building that housed the collection, Williston Hall, burned down due to an electrical fire. So all of that history was just…gone.

Including the Podokesaurus holyokensis fossil. Even worse, to date there have  been no other confirmed fossils   of the species found either, so it’s really gone. But all is not lost!

Researchers at Mount Holyoke have  started an initiative called the   Podokesaurus Project to bring more  attention to this miniature dinosaur. They’re going through all  the surviving records and   archival materials to reexamine  them and see what we can learn. They’re even planning on publishing a new  description and analysis of what branch   of the dinosaur family tree falls in,  shedding new light on some old bones.

And in 2021, Podokesaurus got some extra love when it was named the state dinosaur of Massachusetts. Not bad for a skeleton lost to time twice. Which brings us to our next missing fossil.

But before we dig into that, a quick ad! This SciShow video is supported by ACT. Maybe you know ACT as the makers of  the #1 taken college admissions test   in nearly half of U.

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The enhanced ACT boasts the shortest test  time yet with more time per question. That way you have less time pressure  and more time to go back and review   your answers or work through the harder questions. These enhancements reflect ACT’s  commitment to student feedback.

After all, you’re the one taking the test. You can learn more about the  ACT and decide if it’s right   for you by scanning the QR code or  clicking the link in the description. While it’s great that Podokesaurus got  her flowers in the end, other lost fossils   are controversial enough that they probably  won’t be named a state fossil any time soon.

Take Spinosaurus aegyptiacus for example. In 1912, a German fossil collector, with  support from a German paleontologist and   the Bavarian Academy of Sciences, discovered  a partial dinosaur skeleton in western Egypt. They found some crocodile-like teeth, a lower  jaw, and vertebrae with large spines on them.

These spines would have stuck upwards  in a sail shape, which could have been   used for maintaining temperature,  to help it swim, or as a display. Or maybe it wasn’t a sail at all, and was  really just a hump that stored fat or something. Spinosaurus was the largest carnivorous dinosaur  ever discovered, with a body as long as 18 meters.

For comparison, our friend Tyrannosaurus  rex was about 14 meters long. A couple of decades later,   a second batch of spinosaur fossils  were discovered in the same location. They had some similarities with the first  specimen, but were different enough that they   couldn’t say for sure whether the bones belonged  to Spinosaurus aegyptiacus or a new species.

The fossils were shipped back to the  Paleontological Museum in Munich,   where both specimens resided until the night of April 24th, 1944, in the middle of World War II. The building where those fossils were  kept got hit during a bombing raid by   the British Royal Air Force, and most of the  fossil collection from Egypt was destroyed. Fortunately, the researchers’ notes and drawings  survived, but those can only capture so much.

It’s especially frustrating because several  more fossils in its genus have been discovered   since 1944, fueling some pretty intense  debates about the different species. And the fighting doesn’t stop  with species distinctions. Paleontologists also argue  over where these guys lived.

Specifically, whether they were aquatic  or semi-aquatic predatory dinosaurs. If they were, they’d be the first, so it’s  pretty important to get that one right. As more specimens have come to light,  scientists have confirmed the predatory part.

Spinosaurus ate fish, and had a  whole bunch of adaptations that   would have allowed them to live in water, too. Their nostrils are oriented to  keep water out while swimming,   and their bones were pretty buoyant. Plus, with their long necks and short hind  legs, walking on land might’ve been difficult,   leading some to speculate that swimming  was their preferred mode of transportation.

Other researchers don’t deny that  these adaptations are present,   but say that there are other things  that could explain these traits besides   an aquatic lifestyle, and even some  that say the water was a total no-go. Computer modeling studies indicate that  given its body shape, a spinosaur in water   would just keep tipping over and rolling onto  its side, which isn’t ideal for a predator. And their bones are actually so buoyant  that they might not have been able to,   like, submerge themselves to swim, which  again, not ideal for an aquatic predator.

So without those all-important missing fossils,   we may never know whether  this idea would sink or swim. To be fair, these kinds of paleontology fires  don’t actually need that much fuel to burn,   because historically speaking,  paleontologists are a fiery bunch. Case in point, the Bone Wars.

In the late 1800s, the rival paleontologists O. C. Marsh and Edward Cope were fighting to prove   themselves as the best fossil  finders the world had ever seen.

And when it came to trashing each  other, they did not hold back. There were spies, there was bribery, there  was publicly sullying each other’s honor. They even tried to inflate their own stats,   naming nearly every single fossil  they found as a brand-new species.

It was a whole thing. And while the paleontologists involved came  out of their feud broke and discredited,   they still did find a lot of dinosaur fossils. Including a massive sauropod,  Amphicoelias fragillimus....

Maybe. In 1878, a paleontologist working for Edward Cope  discovered a piece of a vertebra in Colorado. The arch of this particular vertebra  was 1 and a half meters tall.

Which is about the size of a pool cue. From that massive backbone,  it’s been estimated that the   whole dino would’ve been 58 meters long  and weighed more than 122,000 kilograms. That is a dinosaur almost as  long as an ice hockey rink.

And that’s way way bigger than  any other dinosaur ever described. A dinosaur of that size would  quite literally be ground breaking. Around the turn of the 20th century, the  vertebra was sent from Cope’s private   collection to the American Museum  of Natural History in New York,   where it was received, checked  in, and assigned a catalog number.

Two decades later, the museum finally decided  to go through the Cope’s extensive donated   collection, and discovered that the Amphicoelias  fragillimus fossil just… wasn’t there. They had no idea where it had  gone or what happened to it. It was just missing.

So all scientists have to go on are the  original notes and Cope’s original description. Which leaves room for lots of  controversy and speculation. Some scholars even suspect that  in the frenzy of the Bone Wars,   Cope made a typo when writing down  the size of the vertebra’s arch.

Instead of being 1.5 meters tall, they  think it may have only been 1.05 meters,   which would drastically  reduce the body size estimate. Other scholars think that the  measurements could have been right,   but the math used to extrapolate that  to the size of a whole animal was wonky. However, it’s now known that Cope’s rivals had  actual spies embedded on his research team.

So if he’d flubbed his numbers, those  spies would have ratted him out. Sadly nobody’s found any other fossils from  this big boy that would confirm his size. And there’s another problem.

When other researchers looked at the drawings,   they suggested that the bone may have come  from a different taxon of dinosaur altogether,   which would change the calculations for estimating  the size of the animal from its vertebra. And if it is from this other dino  group, the math says this dinosaur   would be 30 to 32 meters long, which  is still big, just not record-breaking. But without the fossil, we’ll never really know.

It’s a mystery, and a big one at that. Fortunately, sometimes  missing fossils do come back. Which brings us to our final titan of the fossil  world and a story nearly 200 years in the making.

In 1828, dinosaur fossils  were discovered in India. These were the first dinosaur  fossils ever found in India,   and dated back to about 70 million years ago,  back before India had joined up with Asia,   bringing species from other  parts of the globe with it. At this point in history, it  was actually down near Africa.

The fossils were passed around for  a while before they were described   in 1877 and recognized as a new genus and  species of dinosaur: Titanosaurus indicus. But after that, they just disappeared. Nobody really knew where they had  gone or what happened to them.

And they weren’t alone, because a ton of Indian  fossils have gone missing over the years. Which is a bummer, since figuring out  what species were around in India,   and when they got there, could tell  us a lot about how species spread. So India’s fossil history is a  pretty tantalizing mystery to unpack.

Which is why the Geological Survey of  India and University of Michigan teamed   up to see if they could find some of the  missing fossils amidst the storeroom chaos. And that’s a lot harder than you might think. See, most fossils aren’t like, complete pieces.

They’re bits and pieces of leg bones and ribs. And unless you’re an expert in  exactly that group of creatures,   you might not really know what  you’re looking for in the jumble. Which is why carefully numbering and  cataloging your fossils is super important,   so anyone can tell what they  are and who they belong to.

But for some reason, T. indicus never got its  number, so it had to be recognized by sight. Curators had searched around  where it was supposed to be,   looking for a match, several times with no luck. But this time the team used a  much more systematic approach,   and managed to track down those  Titanosaurus indicus fossils.

And it turns out, it might not be  as giant a discovery as we’d hoped. Titanosaurus indicus has now  been labeled a dubious genus,   because we can’t really tell  if it’s a unique category. There just aren’t enough specimens to know.

Imagine being a fossil reappearing  after decades hidden away,   only for scientists to be like  “actually, you’re not special”. I don’t know about you, but I’d simply go back   into hiding and become yet another  fossil on the never recovered list. [♪ OUTRO]