Amphicoelias fragillimus

This elusive fossil was discovered by the famed paleontologist Edward Drinker Cope, the same man who competed with Othniel Charles Marsh in the infamous “Bone Wars”. Cope discovered many prehistoric fossils, but this one is, by far, the oddest. The only fossil that exists of it was a single vertebra fragment. It was 5 feet high, estimated to be 8.8 feet high if the entire fossil was intact. Compare that to your vertebrae. Yeah. Estimates vary, but they range from 131 to 196 feet in length, making it, by far, the longest creature ever, competing with the blue whale for being the heaviest creature ever (along with another, very elusive sauropd, Bruhathkayosaurus). But, as luck would have it, the fossil just disappeared. It vanished without a trace. Was it a hoax? A misconception? Or was it really the largest animal to ever walk the earth? Sadly, we will probably never know.

Deinocheirus

The only fossil of this dinosaur is a pair of arms. These arms look like they belonged to an ornithomimid but they were 8 feet long. This means that either Deinocheirus towered over the rest of the ornithomimids (and most theropods, since, regarding proportions, it would have been 40 feet long!) or it simply had very long arms for its body. The use of its arms is debated: some say it used them to tear apart large dinosaurs, others say that the claws were too blunt, so they were used as defensive weapons. Some have even said that Deinocheirus used its huge arms to climb trees, although this hypothesis is widely disregarded. Once again, the lack of a body leaves many questions unanswered.

Helicoprion

This bizarre fossil was originally thought to be an ammonite, as the fossil looked like a spiraling, circular shell. However, after some examination, it was revealed that is wasn’t a shell, but a spiraling set of shark teeth, a “tooth whirl”. Unfortunately, due to a lack of a body (cartilage does not fossilize as well as bone), so a guessing game began. It was guessed to be on the shark’s dorsal fin, tail, or even its snout. Thankfully, a skull of a related shark, Ornithoprion, was found to have a tooth-whirl on its lower jaw. The tooth whirl likely contained all of the shark’s teeth that it would use in its life: its older teeth would be moved away to make room for its newer, better teeth. This does not solve the problem yet, however! The tooth whirl was then placed on the tip of the lower jaw but it turns out that that would actually slow down the shark! Perhaps the most accurate representation is one where the tooth whirl existed deep in its mouth instead.

Stethacanthus

Sharks have lasted for over 400 million years. Although they have remained relatively unchanged throughout the fossil record, there are definitely some odd balls. This particular shark had an anvil-shaped dorsal fin, with small spikes on it, as well as having a very bizarre growth on its head. The fin could have been used for courtship or for defense.

Dunkleosteus

One of the scariest creatures ever to live in the ocean, this Devonian fish could grow up to 33 feet long, had an armored face, and likely had one of the strongest bites in history! It used a beak-like mouth instead of teeth to devourer its prey. It was one of the largest of the Placoderms, a group of armored fish that are now extinct.

Pterodaustro

This pterosaur had an unusual set of teeth, similar to the baleen of some whales. It almost certainly used these teeth to eat small, aquatic organisms, similar to the way a flamingo eats brine shrimp. Since flamingos get their pinkish hue from their diet, Pterodaustro might have been pinkish too.

Nyctosaurus

This genus of pterosaurs is the only one that does not have claws on its wings. Otherwise, most species looked quite average, similar to the famous Pterodon… until a new, currently unnamed species was discovered in 2003. The species had a huge, antler-like crest, larger than any other pterosaurs crest. Some speculated that there was a flap of tissue in between these antlers, like some other pterosaurs, which could have been used like a sail to enhance its flight. However, research shows that a crest that large would actually impair its flight, so it likely just had an odd set of antlers.