Even if you are not new to dinosaurs, knowing what are the common dinosaur types and how dinosaurs are grouped can go a long way to helping a beginner understand the big picture about types of dinosaurs. This makes me wonder, what exactly are the main types of dinosaurs?
The three most common dinosaur types are carnivores, herbivores, and omnivores. Dinosaurs across seven groups belonged to one of these three types: pachycephalosaurs, ceratopsians, ornithopods, ankylosaurs, stegosaurs, sauropods, and theropods.
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Interestingly, if I could go back a few decades and get a solid way to approach understanding dinosaurs, I would start by memorizing the three most common dinosaur types and the key seven groups I will outline in this article. It would have helped me immensely.
If you want to learn even more about the three broad dinosaur types as well as their groupings, this article is for you. I have lots of interesting factoids along the way, so make sure you keep reading!
What Are the Three Types of Dinosaurs?
First, let’s delve deeper into the three most common dinosaur types. To reiterate from the intro, those types include carnivores, herbivores, and omnivores.
Anywhere you went (well, figuratively, of course) throughout the Mesozoic Era, you’d find a mix of all three of these dino types across an ecosystem. This was critical to ensure that dinosaurs could propagate and evolve.
Let’s take a closer look at these dino types now.
The first group of dinosaurs was carnivores or meat-eaters. These ferocious creatures would feed on other dinosaurs and flesh-and-blood species outside of dinos.
Although the Tyrannosaurus is probably the first dinosaur that comes to mind when you think of carnivores and is thus the most popular in this group, he is far from the only one.
From the Spinosaurus to the Giganotosaurus as well as the Velociraptor, Carnotaurus, Saurischia, and Allosaurus, all were carnivores.
Theropods were also carnivorous, even though they didn’t stay that way. Through time and survival necessity, theropods later became piscivores (fish eaters), omnivores (both meat and plant eaters), and herbivores, which is our next group.
It’s estimated that as many as 65 percent of dinosaurs were herbivores, which meant they consumed plant matter instead of each other.
Why did so many dinosaurs eat plants? They were everywhere!
According to Science Focus.com, the warm conditions prevalent in the Triassic, Jurassic, and Cretaceous Periods raised carbon dioxide four times greater than modern-day CO2 levels.
The carbon dioxide produced plants to a highly prevalent degree that the dinosaurs that chose to eat plant matter never had a food shortage. The consistency of their next meal would have allowed herbivorous dinosaurs to grow to the sizes they did.
These were huge dinosaurs too, often with long necks to assist them in eating from treetops and other high sources.
Some plant-eating dinosaurs are Brachiosaurus, Diplodocus, Apatosaurus, Alamosaurus, Mamenchisaurus, Giraffatitan, Barosaurus, Saltasaurus, and Anchisaurus.
Sauropods were exclusively herbivorous, and some of the dinosaur species listed above belong to that group.
The last group of dinosaurs is omnivores or both plant-eaters and meat-eaters depending on the circumstance.
By far, the fewest dinosaurs were omnivores, including dinosaur groups such as Troodontids, Ornithomimosaurs, and Oviraptorosaurs. Some species include Oviraptor, Avimimus, Chirostenotes, Gallimimus, Garudimimus, Deinocheirus, and Gigantoraptor.
What Are the Seven Main Groups of Dinosaurs?
Besides categorizing dinosaurs by their diets, you can also classify them according to one of seven main dinosaur groups as we mentioned in the intro. Let’s go over them now.
The first group is the theropods or Theropoda, a clade that featured species with three toes per limb as well as hollow bones.
As we mentioned before, theropods were initially carnivores, and some species stayed that way throughout this clade’s existence. Others changed their diets to survive.
Birds came from Jurassic coelurosaurian theropods and today account for 10,500 species.
Of course, we cannot talk about theropods without discussing the T. Rex, arguably the best-known theropod and the best-known dinosaur period.
As part of the tyrannosaurid family, the T. Rex was further-spreading, as this creature roamed what has since become western North America. The T. Rex is classified by its gigantic and weighty tail, large skull, strong and sturdy back legs, and much shorter arms.
The T. Rex is believed to have measured up to 40.7 feet long and weighed between 9.3 and 15.4. short tons.
The next group I’ll examine is the sauropods or Sauropoda, which are “lizard-hipped” dinos with a name that also translates to “lizard-footed.”
As we touched on, sauropods are known for their tremendously long necks, although those necks are shortened evolutionarily over time. A sauropod had a much smaller head than its proportions would dictate, yet its legs were akin to pillars and quite thick.
The tail of a sauropod was large and thick as well.
One sauropod species is the Vulcanodon aka â€œvolcano tooth, which lived during the Early Jurassic Period in southern Africa today.
The Vulcanodon was one of the first sauropods discovered and thus paved the way for many paleontologists’ knowledge about this genus today.
The single species in this genus, the V. karibaensis, was known for its long tail and neck, columnal legs, and broad body. Still, this species was quite small, only 36 feet long.
Now, look at the Brachiosaurus, a Late Jurassic theropod that lived over 150 million years ago in modern-day North America near Colorado.
As part of the Brachiosauridae family, the Brachiosaurus is a smaller genus that might have been able to reach 30 feet high to eat leaves directly from the trees. However, the Brachiosaurus is believed to have not used its hindlimbs for rearing, a trait that most other sauropods possess.
The third group of dinosaurs is stegosaurs or Stegosauria, which are Jurassic and Cretaceous Period dinosaurs that were herbivores and ornithischians (with a bird-like pelvic structure). Stegosaurs lived in what is Asia, South America, Africa, Europe, and North America today.
The Stegosaurus is synonymous with stegosaurs, so we thought it was only right to talk about this genus.
The Late Jurassic Stegosaurus is known for its armored plates all down its spine as well as its tail spikes. The four-legged herbivore has at least three known species: S. sulcatus, S. ungulates, and S. stenops.
The Stegosaurus lived about 150 million years ago and would have shared an environment with Torvosaurus, Allosaurus, Ceratosaurus, Brachiosaurus, Diplodocus, and Apatosaurus. Dinosaur experts believe that Tarvosaurus and Allosaurus specifically might have fed on Stegosaurus.
The ankylosaur or Ankylosauria group also included herbivores much like the Stegosauria group. The closest modern-day animal to ankylosaurs is the turtle, as ankylosaurus dinosaurs had armor-like osteoderms.
Ankylosaurs were four-legged dinosaurs. Despite that they had shorter limbs, those limbs were exceptionally powerful.
In this group is the Ankylosaurus, an armored dinosaur from the Cretaceous period that lived about 65 million years ago in what is today western North America. It was one of the last types of non-avian dinosaurs.
The Ankylosaurus was about 26 feet long but heavy, weighing up to 8.8 short tons. Its body was large and broad with a low and wide skull. That skull featured dual horns aimed backward from the back of the Ankylosaurus’ head.
This dinosaur also had sideways-facing nostrils, which other ankylosaurs did not. Ankylosaurus also had a beak.
The biggest trademark of the Ankylosaurus by far is its osteoderms or armor plates, of which this dinosaur had many. Its tail also featured a club that undoubtedly could have been used as a weapon if the need arose.
Next are the ornithopods or Ornithopoda clade. These bipedal grazers were initially quite small and later became larger and more multiple. With time, the ornithopods were the most dominant herbivorous group of the Cretaceous, especially in what is today North America.
The Gasparinisaura is one genus of ornithopods that lived during the Late Cretaceous Period. This dino has a name that means “Gaspirini’s lizard” Its fossils were only uncovered in the early 1990s, so the knowledge we have on the Gasparinisaura is quite fresh!
This bipedal genus was herbivorous and on the smaller side, measuring only 5.6 feet long and weighing under 30 pounds. The Gasparinisaura had a long, round head with oversized eye sockets.
The second-to-last dinosaur group is the ceratopsians or Ceratopsia, which comes from the Greek word for “horned faces”. These beaked herbivores lived during the Cretaceous Period in what is modern-day Asia, Europe, and North America.
The Yinlong is one of the oldest ceratopsians, dating back to the Jurassic Period when this dinosaurâ€™s ancestral forms lived. Herbivorous and bipedal, the Yinlong was recovered in central Asia.
A skeletal sample was found in 2004 in Chin’s Xinjiang Province that was nearly intact. That is how we know this dinosaur weighed roughly 33 pounds and was only 3.9 feet long.
We have to include the Triceratops in this section as well, as he’s the most famed ceratopsian. The Triceratops lived during the Late Cretaceous Period about 68 million years back in modern-day North America.
Its name translates to “three-horned face” in Greek, as the triceratops had triple horns as well as a neck frill. This genus was among the largest of the ceratopsians, as the average size of a Triceratops was just under 30 feet long and about 13 short tons in weight.
Fun fact: the T. Rex might have preyed on Triceratops!
The last dinosaur group is the Pachycephalosaurs, which shared a clade with the Ceratopsia called the Marginocephalia.
These dinosaurs mostly lived throughout the Late Cretaceous Period and in the Northern Hemisphere. Known for their exceptionally thick skulls, Pachycephalosaur dinos were sometimes herbivorous and sometimes omnivorous depending on the genus and species.
One such genus is the Pachycephalosaurs, a Late Cretaceous dinosaur from modern-day North America with a skull up to nine inches thick along the roof.
Pachycephalosaurs were herbivorous. This genus also had tiny forelimbs but much longer hindlimbs, sort of like a T. Rex.
What Was the Most Common Dinosaur in the Jurassic Period? What About the Cretaceous?
Now that weâ€™ve designated dinosaurs in 10 different ways, we thought weâ€™d wrap up by putting this information into perspective via time periods.
We just wrote a very informative guide on the blog about the Triassic, Jurassic, and Cretaceous Periods (which altogether make up the Mesozoic Era) that are worth reading if you get the chance.
For now, we want to examine the dinosaur species that were the most prevalent across two of those eras, the Jurassic and Cretaceous Periods.
Although maybe not the most well-known, the Camarasaurus was the most common dinosaur in the Late Jurassic Period. This North American-dwelling sauropod had an arched skull but a rather short snout.
The dinosaur also had a long neck and legs but a shorter tail. The dinosaur measured about 75 feet long and might have weighed up to 51.8 tons.
As for the most common dinosaurs of the Cretaceous Period? Those would be many of the species weâ€™ve talked about throughout this guide, including the T. Rex, the Triceratops, the Pachycephalosaurs, and ankylosaurs.
With more than 700 dinosaur species in existence and counting, it makes sense to categorize them into types by their diet and groups such as by clade. Now that you understand more about how these dinosaurs are classed, we hope it expands your knowledge and appreciation for the fascinating world of dinosaurs!