It’s dinosaur week here at MiniZoo! Since its part of our job to know and learn about these ancient creatures, we thought it’d be cool to share some of our knowledge with our like-minded Dino-loving friends.

There are several main categories of dinosaurs, and I find knowing these categories to be super helpful in understanding context, common ancestors and how different groups are related (or not related). It also helps me to keep up with my dinosaur-loving kids.

Firstly, there are two overarching dinosaur groups which are defined by their hip bone structure: Ornithischian (closed hip structure, similar to birds) and Saurischian (open hip structure, more like lizards). Of course, like most things, there are exceptions, e.g. dinosaurs who were Saurischian and evolved into Ornithischian dinosaurs, dinosaurs which don’t fit easily into one category, and palaeontologists who don't agree on the classification system altogether.

However, without getting too caught up in scientific research and arguments, I find it easy to classify dinos using the seven main categories which fall under those two overarching hip-defining ones, merely because their physical attributes are generally easy to identify.

Saurischian [saw-i-ski-en]

1. Theropods
2. Sauropods

Ornithischian [orn-a-thi-ski-en]

1. Stegosaurs
2. Ankylosaurs
3. Ornithopods
4. Ceratopsians
5. Pachycephalosaurs

Theropods [ther-a-pods]

Often carnivorous, or meat eating (though not all), the word ‘theropod’ refers to their hollow bones, meaning they were rather lightweight creatures and likely more agile and fast. They also typically had three-toed feet with sharp claws, and many are suspected to have feathers, so their likeness to modern birds is obvious - in fact, it is believed they were the ancestors of birds. Theropods also typically had four limbs, but walked on the two lower ones. For some, the upper limbs were feathered and wing-like, and for others, these upper limbs look pretty useless as they were so small. This classification includes the dilophosaurus, as well as ceratosaurs like a giant carnotaurus, tyrannosaurs, allosaurs, megalosaurs, raptors, compsognathus, and plenty more.

Image features the Papo Compsognathus, the Safari Carnotaurus, the CollectA Megalosaurus in Ambush, the Schleich Tyrannosaurus Rex 2018, the Safari Velociraptor, the Mojo Allosaurus, and the Schleich Dilophosaurus. 

Sauropods [sawr-o-pods]

Research tells us that these guys most likely started out bipedal (walking on two legs) and omnivores (eating both plant and meat), using their sharp claws on their upper limbs to tear vegetation, and their elongated neck to reach some delicious heights. However, over time, these creatures got larger, longer and heavier, and they evolved into quadrupeds (walking on four legs) to support their weight. They also would swallow and keep small stones in their gizzards to help break down their leafy plant lunch, instead of chewing. Well known sauropods include the mamenchisaurus, diplodocus, brontosaurus and brachiosaurus.

Image features the Papo Brachiosaurus, CollectA Brontosaurus, Mojo Diplodocus, and the CollectA Mamenchisaurus Deluxe.

Stegosaurs [steg-uh-saws]

These famous guys were usually herbivorous (plant eaters), and defensively armoured, often featuring bone-like plated spines protruding on their back, and deadly tail spikes. Their beak-like mouth is an easily identifiable feature, and they were almost exclusively quadrupeds, heavy and slow-moving. Stegosaurs include the miragaia, tuojiangosaurus, huayangosaurus, kentrosaurus and more.

Image features the Mojo Stegosaurus, the CollectA Miragaia, and the CollectA Kentrosaurus.

Ankylosaurs [an-ke-lo-saws]

Similar to the stegosaurs, the ankylosaurs were also heavily armoured, but more so like a tank, and very well protected from attackers. Some were more spiky, and others featured a mighty club tail, but not often both. So despite its herbivorous eating habits, it was still a dinosaur to avoid. Ankylosaurs are pretty easy to identify due to their armoured features, but specific ankylosaurs include gastonia, polacanthus, pinacosaurus, and minmi.

Image features the Schleich Ankylosaur, the CollectA Minmi, the CollectA Gastonia, and the Papo Polacanthus.

Ornithopods [or-nith-a-pods]

These dinosaurs had bird-like feet, however, these ones didn’t actually evolve into birds, that’s the theropods, remember? It's their mouth, or specifically chewing teeth that set them apart from the rest, as these herbivores may have ruminated on tough vegetation, like a modern cow might. Ornithopods also probably began as bipeds but as they grew, they began to use their upper limbs more for stability, similar to the sauropods. Many also featured cranial crests, some hollow, some solid, perhaps once used to assist in making sounds and calls to others. Famous ornithopods include the iguanodon, hadrosaurs including the edmontosaurus, and lambeosaurs including the parasaurolophus.

Image features CollectA Iguanodon Deluxe, the CollectA Edmontosaurus Deluxe, and the CollectA Parasaurolophus Deluxe.

Ceratopsians [se-ra-top-si-ans]

These famous creatures are our horned dinosaurs, though not all of them had facial horns. They are typically characterised by their easily identifiable neck frill, a strong bony structure at the base of its skull, many of which featured spikes on their head, some long, some short, some dinos which have one, some with three, some with more! These were most likely used for defensive purposes. The ceratopsian family includes the protoceratops and triceratops.

Image features the Mojo Triceratops and the CollectA Deluxe Protoceratops.

Pachycephalosaurs [pa-ke-sef-a-la-saws]

These guys were one of the smallest of the dinosaur types, as the largest pachycephalosaurs were about the height of a human. These bipedal, mostly herbivorous dinos had a dome-like head lined with spikey spines. While this group includes the stigymoloch and dracorex, many believe these are the same species, but just at different sex, age, or maturation.

Image features the Scheich Dracorex and the Safari Pachycephalosaurus.

So those are the seven main categories of dinoaurs, but you’re probably thinking, what about pterosaurs?! My personal favourites, these ‘flying dinosaurs’ were technically not dinosaurs at all, as they don't fall into the two overarching groups, Ornithischian or Saurischian.

Pterosaurs [teh-ra-saws]

Pterosaurs include both pterodactyls and pteranodons. What’s the difference? Well, firstly they lived during different prehistoric periods, so far apart that they likely never lived at the same time. Pteranodons were large and winged (in fact, the largest flying creature ever to have lived), and typically had hard heads with bone-like crests. They also didn’t have a tail or teeth, so they ate things like fish and insects, like a common seabird would, as they had a pelican-like beak. Pterodactyls were smaller and had softer heads. Pterodactyls had sharp teeth, so they could eat meatier prey like small mammals and dinosaurs, and this species includes the dimorphodon, quetzalcoatlus, ornithocheirus and more. We also have a range of pteranodons at MiniZoo including the impressive sternbergi.

Image features the Papo Pteranodon, the CollectA Ornithocheirus, the Safari Dimorphodon, the CollectA Quetzalcoatlus with Prey, and the CollectA Pteranodon Sternbergi Deluxe with Moveable Jaw.

Another group of non-dinosaur prehistoric creatures are marine reptiles. While some actual dinosaurs (listed above) could, and often did, swim (most famously the spinosaurus), the majority of aquatic ‘dinosaurs’, are actually not dinosaurs either, and so they fall under a new descriptive category: marine reptiles. While marine reptiles are really among the very first fossils ever found, they simply weren’t dinosaurs. Basically a dinosaur needs to be able to stand upright in order to receive the classification (consider the hip bone structure mentioned at the beginning), and anything with flippers really can’t do that.

Marine Reptiles

This category encompasses a large range of prehistoric creatures including plesiosaurs, mosasaurs, ichthyosaurs, elasmosaurus and kronosaurus. Most of these featured four flippers and were carnivorous. While the elasmosaurus had a long neck, and the ichythosaurus was more dolphin-like, its the mosasaurs that dominated the oceans at more than 15 meters in length!

Image features the CollectA Elasmosaurus, the Schleich Mosasaurus, and the Papo Plesiosaurus.

I do not pretend to be a palaeontologist, and there is A LOT more information out there about these prehistoric creatures. Within each of these major groups are even more specific types of dinosaurs, but it does get pretty scientific and technical. So I find these 7 groups (plus the pterosaurs and marine reptiles) to be a helpful guide for understanding basic differences, categorising dinosaurs and seeing their evolution. I hope this little science history lesson helps you in your shopping, play, display, and keeping up with your dino-obsessed little ones!

Follow us on Facebook, Instagram, YouTube and Forums to see upcoming dinosaur model releases, more brand comparisons, discuss figurines and features with like-minded people and brush up on dinosaur knowledge and pronunciations.

Jenna @ MiniZoo