When it comes to prehistoric critters, it can be real easy to point at any large, scaly beast and call it a dinosaur.  But there are a lot of prehistoric critters that were not dinosaurs, even during their heyday.  In fact, dinosaurs are only a small fraction of the animals that walked around during the “Age of Reptiles”.

Unfortunately, sometimes even “educational” books and movies will lump in the other critters in the same group as the dinosaurs.  So how can you tell which is which?

Let’s have some fun with a little quiz. Can you tell me which critters are the dinosaurs, and which ones aren’t?

First off, a handy dandy dino checklist. 

• Dinosaur hips make for straight, sturdy legs under their bodies, just like mammals.  Unlike other reptiles that walk with legs splayed out, dinos tend to walk with one foot in front of the other, just like we do.

• Dinosaurs all lived in the Mesozoic period up to the present day.  Birds, of course, can be seen outside your kitchen window.  All other dinosaurs, or non-avian (not-bird) dinosaurs, appeared in the Triassic, reigned all through the Jurassic, and met their end at the Cretaceous.

• All Dinosaurs share the same latest common ancestor- the great-great-great-grandaddy of Iguanodon and Megalosaurus.  Iguanodon is a giant, spike-thumbed plant-eater from Cretaceous England.  Megalosaurus is a meat-eating distant cousin of T-rex, from Jurassic England.

Fun Fact on that last one:

Sir Richard Owen coined the name Dinosauria based on Megalosaurus, Iguanodon, and Hylaeosaurus (a plant-eater built like an armored tank, but without the club-tail of more popular armored dinos.  Cretaceous England).

All three of these critters can still be seen today at the Crystal Palace in London, where sculptures were built based on the latest scientific knowledge of the 19th century.  It’s in a sad state compared to the grandeur of its golden years, but it’s still on my bucket list. 😀

Dinosauria is often translated from the Greek as “Terrible Lizard”, but it can also translate to “Fearfully Great Reptile”.  Owen seems to have named the creatures based on their awesome size and how majestic they must’ve looked in life.  Not on their “terrible” teeth, spikes, and claws.

Now that you know the features that make a dinosaur, let’s get started! 😀  I’ll leave the answers for the very end, so that you can test yourself.

First up, Bowser the Ceratosaurus!  He’s big, and lived in Jurassic North America.  He has a nice beefy tail with the muscle power to move his legs forward, one foot in front of the other.

Look who’s come out of hiding…Nessie the Plesiosaurus!  Those flippers are great for gliding through shallow Jurassic seas or paddling in murky rivers.  You’ll find her swimming around in Jurassic England.

Here comes Bella the Camarasaurus!  She’s a big girl, and proud of it, but she has no problem moving all that weight around.  Her legs are like pillars, strong and sturdy under her body.  You can find her in Jurassic North America.

Why hello there, Dan the Dimetrodon is here for a special visit.  He came by all the way from Permian North America, an earlier time than the Triassic period.

Twig the Compsognathus is a little guy, only as big as a turkey, but that just means he’s extra fast.  He runs like a roadrunner, and easily snatches up splay-legged lizards.  You can find him in Jurassic Germany.

(quick note: there are rumors of scale patches on the legs and tail for this little guy, but I haven’t been able to find the papers describing them.  So I’ve given him feathers based on a close cousin.)

Flipper the Ichthyosaurus comes in with a splash! But what is he?  You can find him cruising Asian and European waters during the Triassic and Jurassic periods.

Tango the Archaeopteryx loves to sing and dance, and no lizard can dance like Tango can!  He’s got the finesse of a duck and the enthusiasm of a parakeet.  You can find him and his fancy feathers in Jurassic Germany.

Here comes Tigger the Pliosaurus with a big grin.  An apex predator in the water, this big guy would’ve made the Jurassic seas around Europe and South America a dangerous place to be.

Are those…Turkeys?  Why yes, yes they are.  They’re showing off their festive plumage by strutting with one foot in front of the other.  You probably see one at your dinner table on occasion.

Ron the Rhamphorynchus has dropped by to see you.  Those teeth look a bit vicious, but he’s just an excitable fuzzball really.  You can find him soaring through the Jurassic skies in Germany.

Think you got them all?  Let’s check and see!

• Bowser the Ceratosaurus is a dinosaur!  He stands upright with his legs under his body, he’s a theropod (who were the theropod dinosaurs?), and he lived during the Jurassic period- the middle of the Mesozoic era.

• Nessie the Plesiosaurus is not a dinosaur!  She lived at the same time as many dinosaurs, and she’s big and scaly, so I can understand why she’s often thrown into the pile. She’s a marine reptile called a plesiosaur, and she’s actually the first discovered, so she got to name the whole group!

• Bella the Camarasaurus is a dinosaur!  She stands tall and straight on legs like pillars, and she lived in about the same time and place as Bowser.

• Dan the Dimetrodon is not a dinosaur!  Dan is quite a few million years too early, with the biggest mass extinction in Earth’s history between him and dinosaurs.  But if you don’t know what time he’s from, then you can see that his legs are sticking out like a croc, instead of underneath his body.  But he’s not a croc either.  He’s a synapsid.  Mostly that’s a fancy term about the skull.  I’ll get to that when I’m working on the Permian period. 😀  That said, I totally get why people would think it’s a dinosaur.  I mean, it’s everywhere!  It’s even on my kids’ favorite oatmeal, y’know the one with the hatching dinosaur eggs?

• Twig the Compsognathus is a dinosaur!  Size doesn’t matter when it comes to dinos.  This little guy has his feet under him, lives in the Jurassic, and he’s a tiny cousin of Megalosaurus.  Not so sure about the feathers?  I talked about feathers on dinosaurs in a post not too long ago…

• Flipper the Ichthyosaurus is not a dinosaur!  He’s also not a fish, dolphin, or prehistoric whale.  He’s a marine reptile called an Ichthyosaur, and he was the first of his kind discovered, so he got to be the namesake of his group.  Since the name translates to “fish lizard” or “fish reptile”, then there’s no surprise when people call him one.  The reason he looks like a dolphin is because the fishy/dolphin/shark body plan is so perfect.  For an animal that is born, lives, and dies in water, then his body shape is perfect.

Fun fact: Plesiosaurus was given that name because her kind is “nearer to dinosaurs” than Ichthyosaurs like Flipper.

• Tango the Archaeopteryx is a dinosaur!  Few deny the birdiness of this critter.  Where some people get confused is the dinosaurness of birds…but this little guy is a lovely mix of both.  But now you’re getting to know the drill.  Feet underneath the body and supporting his weight.  Jurassic period, “golden age” of dinos…etcetera, etcetera… 🙂

• Tigger the Pliosaurus is not a dinosaur!  It’s starting to look like there are no swimming dinosaurs. There are always exceptions to the rule of course *cough*Spinosaurus*cough*, but in general, you don’t really see dinosaurs getting specialized for a life in water.  Tigger is another that gets to name his own group.  The Pliosaurs.  They were marine reptiles that thrived in the Jurassic and into the Cretaceous, but died out alongside the dinosaurs.

• A Turkey is a dinosaur! Yes, when you sit down for that turkey sandwich, or prepare for that Thanksgiving feast, you are about to eat a dinosaur.  All birds are members of the theropod group (take a look at Bowser up there).  Want more info?  I’ve got a post on birds over here.

• Ron the Rhamphorynchus is not a dinosaur! Like the marine reptiles, his kind lived at the same time, and so are always being tossed onto the same pile.  Ron is a Pterosaur, a flying reptile that is actually in the same family tree as crocs and dinosaurs, but not so close that he’s mixed in with the dinosaurs.  Pterosaurs were usually pretty good at walking, but they didn’t have the same hip as dinos.

How did you do?  If you didn’t do very well, don’t feel too bad.  There’s a lot of misinformation out there, even from sources that are supposed to be educational.  And really, it’s a lot easier just to call them all dinosaurs, instead of having to remember all the different names for the different groups.  🙂

Quick Question:  What’s your biggest source of info about dinosaurs?  Jurassic Park?  The news?  Dino obsessed friend or kid?  Your own research?  I’d love to hear from you in the comments!  😀