When Dinosaurs Ruled The Mind #29: Top 10 Dinosaurs That Sadly Never Were

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OK, so I lied a little. I know the trailer came out early. I want to talk about it too. But my OCD is telling me to make my opinion of the Jurassic World trailer my 30th post on When Dinosaurs ruled The Mind. I’ve made this little list to fill in the gap. So, I’ll make this one nice and short, and focus on a topic we’ve all thought about: dinosaurs that we loved as kids but science doesn’t recognize anymore.

There are lot’s of reasons this might happen; bones might get jumbled from two creatures and are mistaken to be from one, a younger member of a known species gets assigned as its own genus, plain misidentification, so on and so forth. But these creatures might become beloved to the kids of their generation, and they may become unhappy that they have to give them up. This is for all those kids. I’m here to avenge you.

Anyway, let’s get right into the list.

10. Torosaurus


Now, this guy is number 10 because there are many who still consider it a valid genus, but the debate goes on. There are quite a few who now consider that Torosaurus might actually be a Triceratops in its most mature form.

Many people are still debating over this, and claim Torosaurus is distinct enough to merit its own genus. Now, scientists have recently been studying how much bones change in dinosaurs as they grow, and have found out that there is a large amount of change a dinosaur goes through in its life. Many dinosaurs that we once thought were distinct genus’ have since turned out to be juvenile forms of already known dinosaurs. Several of the other dinosaurs on this list fall into that same category.

Now, I’m personally on the boat that Torosaurus is really just Triceratops, but I have a feeling this is going to be an argument that will last a while.

9. Seismosaurus

Now, I’ve noticed something. The dinosaurs that have the coolest names always get taken out of the scientific record. Seismosaurus literally means ‘earthquake lizard’. How awesome is that?!

Now, this guy is also low on the list because many still consider it a valid genus, but most scientists now consider it just a very large Diplodocus specimen.

8. Teratosaurus

Now, I remember seeing Teratosaurus a lot in old dinosaur books, even a couple of recent ones. It was once thought that this creature was actually a Triassic ‘carnosaur’, a term they used to use for all big carnivorous dinosaurs that I’m not even sure they still use anymore (BTW, they still do). It was thought to be the ancestor of all big carnivores, only for scientists to later find that it wasn’t a dinosaur at all, it was a rauisuchian, which is basically a giant land crocodile.

You know what that means? No more Teratosaurus in dinosaur books (at least not classed with the other dinosaurs).

7. Altispinax


No, this isn’t an old restoration of a Spinosaurus. This dinosaur, seen in many older dinosaur books as Altispinax, was originally known from only a single tooth. A series of raised vertebrae were attributed with the tooth, and for many years illustrations of this animal would show it with long dorsal spines. However, it is really impossible to point a single tooth to an animal that is only known from vertebrae, so the spine fossils were designated as its own genus, Becklespinax.

So all that remains of Altispinax is a single tooth, and we’ll probably never know for sure what the actual creature looked like.

6. Monoclonius

Monoclonius was another dinosaur you would commonly see in old dinosaur books, especially in the 70’s and 80’s. In fact, you were more likely to see this guy than it’s better known ‘cousin’ Centrosaurus. But this is another case of dinosaurs changing throughout their lifetime. Most of the material that Monoclonius is known from is either very incomplete or can be later identified as younger Centrosaurus’.

This famous ‘Monoclonius’ skeleton has since been labeled a young Centrosaurus.

Dinosaurs whom are known from very little remains and later material from other creatures is attributed to them are call  nomen dubium, and many species on this list fall into that category.

5. Protoavis

The jumble of bones you see above you are from a creature some like to refer to ‘Protoavis’, meaning “first bird”. It was a major discovery because it was thought to be a fully developed bird from the Triassic period, millions of years before the ‘supposed’ first bird Archaeopteryx. This would mean that advanced birds and wing structures appeared millions of years before they were originally thought to, sending the entire scientific community into chaos. Different scientists took it in different ways; some said that this means dinosaurs were more bird like much earlier than we thought, others thought this meant that dinosaurs may have actually come from birds and not the other way around, some show this as proof that dinosaurs and birds are separate creatures, and so on and so forth. But in the end, it turned out to be a jumble of bones from several different creatures that washed together in a flood, only for a scientist to think they were one. In the scientific community, the remains of two or more individual creatures that are accidentally put together and referred to as one is called a chimera. 

But really, the whole argument seems moot now, since Archaeopteryx is now just a pretty average theropod in the eyes of most scientists, feathers have been on dinosaurs LONG before Archaeopteryx, and many now believe feather like structures were present on the ancestors of ALL Archosauria.

4. Stygimoloch


OK, this one kind of hits me personally, because this is one of my favorite dinosaurs. I mean, look at those horns! And its name literally means “demon from the river to the underworld”. Not to mention it was found in Hell Creek, Montana. Everything about it just screams awesome!

But sadly, it’s validity as a valid genus has been called into question in recent years. Scientist Jack Horner suggested his hypothesis that dinosaurs skulls changed shape as they grew up, and that Stygimoloch simply represented a teenage version of Pachycephalosaurus. If you want to hear him explain it more, here’s a link.

He also applies this theory to another pacycephalosaur with a cool name, called Dracorex, who’s name means ‘dragon king’. Why do all the coolest dinosaur names become invalid?

All one big happy family.

3. Ultrasauros

I remember reading old books with Ultrasauros in, and wondering why ‘saurus’ was spelled with an ‘o’. It was claimed to be the biggest sauropod that ever lived, at 100 feet long and 50 ft tall. It was quite famous for a while because of this.

However, it was later found that what we thought was one dinosaur was actually a combination of two dinosaurs, a Brachiosaurus and a diplodocid. This is actually a pretty common mistake, since the Morrison Formation (the place these fossils have been found) is basically a jumbled mess of dinosaur bones, with complete articulate skeletons very hard to find. Dinosaur bones there have a tendency to mix up, leaving to some chimera dinosaurs.

The diplodocid part of the dinosaur is referred to as Supersaurus, which is another dubious name, as some consider it another large specimen of Diplodocus.

2. Nanotyrannus

Another dinosaur with an awesome name. Nanotyrannus, meaning “little tyrant”, was thought to be a miniature tyrannosaur that lived in the same place and time as Tyrannosaurus. I’ve already discussed a bit about this guy in my review of Jurassic Fight Club.

The show points out reasons it can be a different genus, mostly focusing on the skull.


Yes, the skull is very different from that of a full-grown tyrannosaur, but if we’ve learned anything about juvenile dinosaurs, it’s that they go through many and sometimes dramatic changes. So now, Nanotyrannus is considered a juvenile Tyrannosaurus rex. But hey, that’s still very cool, right?

Now, before I give our number one spot, I’ll go through a few honorable mentions.


Known only from teeth, many books used it as a synonym for Edmontosaurus (or Anatosaurus as it was known then). We aren’t really sure what it looked like, but some hypothesis they are actually from a crested hadrosaur like Parasaurolophus or Lambeosaurus.



Troodon was originally known from only teeth, with a skeleton of another small dinosaur discovered later and called Stenonychosaurus. However, scientist realized that the teeth from Troodon were identical to the ones on Stenonynchosaurus, so the name Troodon took precedent.


This dinosaur is only known from fragmentary remains, and most reconstructions are based on this famous (but hypothetical) Charles R. Knight painting.


A pretty recent incident, this is another dinosaur with an awesome name (which means ‘bison horned faced’ and taken from the famous Sioux term), it turned out to be just a juvenile Triceratops.



Syntarsus is odd because even in the 70’s and 80’s, this guy always had that little crest of feathers on it’s head. And that’s a dinosaur that lived just after the Triassic period! It lead many to believe it was an actual trait of the animal, but really it was just a bunch of artists copying each other. Sadly, the name Syntarsus was already taken by a beetle, and it was renamed Megapnosaurus (meaning ‘big dead lizard’, what a troll). However, upon further research it was discovered to be just a species of Coelophysis. And now that feathers on dinosaurs aren’t that big a deal, some modern reconstructions pay homage to this trope.

1. Brontosaurus

Everyone’s favorite dinosaur is not real. Sad but true. Although lots of people still prefer to use this name, what we think of when we here the word Brontosaurus is actually another chimera. Remember when I said because all the dinosaur bones in Morrison Formation are jumbled together it’s easy to get things mixed up? Well, what we know of as Brontosaurus is actually an Apatosaurus body with a Camarasaurus’ head.




Well, that’s it for this list. I’ll get to work right away on that trailer analysis. I have quite a few things to say…


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