Day 4 Types of Dinosaurs

Dinosaurs, like all living things, can be grouped together depending on their physical characteristics and how closely they’re related to each other. Biologists call this ‘classification’.

Animal groups start off large – for example, ‘reptiles’, and get smaller and smaller until you are left with ‘genera’, which are very closely-related species, and finally the individual species themselves. (Genera is the plural of ‘genus’, a Latin word which means ‘origin’, or ‘type’.)

All living things are organized into groups. One of the biggest types of group is a ‘kingdom’. You may have heard of the ‘animal kingdom’, which is the group that contains all animals.

Dinosaurs, mammals, amphibians and humans are all in the animal kingdom.

Dinosaur Names

Most dinosaurs are best-known by their genus, rather than by their species name. For example, most people would talk about the Iguanodon, which is actually a genus, rather than an individual species of Iguanodon.

It’s only paleontologists (and other clever people) who talk about Iguanodon bernissartensis, which is an individual species of Iguanodon.

In fact, most people have only heard about one species of dinosaur – the Tyrannosaurus Rex, which is a species of Tyrannosaurus. All of the other famous dinosaur names, such as Spinosaurus, Allosaurus and Velociraptor, are genera.

New types of dinosaurs are being discovered all of the time, and the way in which they are grouped is continually changing.

On this page we’ll learn about the different types of dinosaurs, and how they are currently grouped.

The Two Main Types Of Dinosaur

There are two main types of dinosaur: saurischia and ornithischia.

It was English paleontologist Harry Seeley who first noticed that were two main types of dinosaur: those whose hips were lizard-like in structure, and those whose hips bird-like in structure.

He called the lizard-hipped dinosaurs ‘saurischians’, which comes from the Greek for ‘lizard hip joint’.

Those with bird-like hips he named ‘ornithischians’, which comes from the Greek for ‘bird hip joint’.

Saurischians Vs Ornithischians

All of the carnivorous (meat-eating) dinosaurs were saurischians, as were many herbivorous (plant-eating) dinosaurs.

In general, all ornithischians were herbivores. However, there may have been a few ornithischians that were omnivorous or even carnivorous.

Fossil evidence suggests that ornithischians lived in herds.

• Saurischians = either carnivores or herbivores
• Ornithischians = nearly all herbivores (possibly some omnivores / partial carnivores). Probably lived in herds.

Confusingly, the ornithischian, or bird-hipped, dinosaurs were NOT the ancestors of birds. Birds evolved from a group of saurischian (lizard-hipped) dinosaurs called theropods.

Types Of Dinosaurs: Saurischians

In this section, we’re going to look at some well-known types of saurischian dinosaurs. The two main types of saurischian dinosaurs are theropods and sauropods.

Theropods

Theropod dinosaurs were bipedal meat eaters. (‘Bipedal’ means that they walked on two legs)

Tyrannosaurus, Spinosaurus, Velociraptor: all of these famous predatory dinosaurs were theropods. The word ‘theropod’ comes from the Greek for ‘wild beast foot’.

Theropods first appeared in the late Triassic period, and were present all the way up to the Cretaceous–Paleogene extinction event which brought the reign of the dinosaurs to an end.

Theropods Become Birds

However, the Cretaceous–Paleogene extinction event wasn’t actually the end for the theropods. One group had already branched off and evolved into birds.

You only have to look out of your window to see that birds – all of which are descended from theropod dinosaurs – are very much alive today!

Types of Theropod Dinosaurs

Coelurosaurs

Coelurosaur means ‘hollow tailed lizard’. Coelurosauria is a large group of dinosaurs that contains theropods that were more like birds than Carnosaurians (a group of dinosaurs which we’ll meet further down the page). The Tyrannosaurids, including T Rex, were coelurosaurs.

Maniraptora

Maniraptora is a branch of bird-like dinosaurs. They first appeared in the Jurassic Period, and are the ancestors of modern-day birds. This group of dinosaurs includes the Dromaeosauridae (raptor) family.

Dromaeosauridae (Raptors)

Dromaeosauridae are sometimes known as ‘raptors’. They were small to medium-sized feathered dinosaurs that appeared in the mid-Jurassic period.

Example Dromaeosaurids

• Velociraptor
• Microraptor

Abelisauridae

Abelisauridae is a family of theropod dinosaurs that lived in Africa, South America and Asia during the Cretaceous period.

Example Abelisaurids

• Carnotaurus
• Abelisaurus

Tyrannosauridae

Named after the Tyrannosaurus (which means ‘tyrant lizard’), Tyrannosauridae is a family of bipedal meat-eaters. Tyrannosaurids are known for their huge skulls, powerful jaws, and short arms.

Perhaps the most famous dinosaur of all, Tyrannosaurus Rex, was a member of the Tyrannosauridae family.

Example Tyrannosaurids

• Tyrannosaurus
• Albertosaurus
• Gorgosaurus
• Tarbosaurus

Spinosauridae

Spinosaurids were another family of large, bipedal, meat-eating dinosaurs. Spinosaurids had long, thin, crocodile-like skulls. Some members of this family, such as Spinosaurus and Baryonyx, were specialized fish-eaters.

Spinosaurus itself had a large sail on its back. This was held up by spine-like bones, from which it got its name (Spinosaurus means ‘spine lizard’). The Spinosauridae family was named after Spinosaurus, but not all members of the family have a similar sail.

Example Spinosaurids

• Spinosaurus
• Baryonyx
• Suchomimus
• Irritator

Carnosauria

Carnosauria is a group of theropods that includes the families Allosauridae and Carcharodontosauridae.

Allosauridae

Allosauridae is a family of predatory dinosaurs that lived in the late Jurassic and early Cretaceous periods. Its best-known member is Allosaurus, which was a top of the food chain predator of the late Jurassic period.

Example Allosaurids

• Allosaurus
• Saurophaganax

Carcharodontosauridae

Carcharodontosauridae is a family of dinosaurs that includes some of the largest land carnivores that ever lived. The name comes from the Greek for ‘shark-toothed lizards’.

Example Carcharodontosaurids

• Giganotosaurus
• Carcharodontosaurus
• Tyrannotitan

Sauropods

The sauropods were a group of saurischian dinosaurs. Many sauropods grew to incredible sizes, and the group contains the biggest land animals ever to walk the earth.

Giant dinosaurs such as Apatosaurus, Diplodocus, and Titanosaurus were all sauropods.

A typical sauropod had a large barrel-shaped body, a long neck, a small head, and a long, powerful tail. It stood on four tree-trunk like legs.

Diplodocidae

Diplodocidae is a family of sauropod dinosaurs. Members of this family typically had very long bodies, but were not as tall as other sauropods.

Example Diplodocids

• Diplodocus
• Apatosaurus
• Brontosaurus
• Supersaurus

Titanosauria

Titanosaurs were a group of sauropod dinosaurs that appeared in the early Cretaceous and lived right up to the end of the Mesozoic era. The group includes Argentinosaurus, a genus which, although only known from a small selection of bones, was possibly the largest ever land animal.

Example Titanosaurs

• Saltasaurus
• Argentinosaurus

Types Of Dinosaurs: Ornithischians

As we’ve seen, the Ornithischian (bird-hipped) dinosaurs were one of the two main types of dinosaurs (the other being the lizard-hipped Saurischians).

Many Ornithischians had beaks and jaws that were adapted for cutting and chewing plants

Some of the best-known types of Ornithischian dinosaurs are listed below.

Thyreophora (Armored Dinosaurs)

Thyreophora was a branch of ornithischian dinosaurs. Thyreophora means ‘shield bearers’, and another name for this group is ‘armored dinosaurs’.

Thyreophorans were heavily armored with thick skin and rows of plates running along their bodies. Many were further protected by spikes and tail clubs.

Two well-known groups of Thyreophorans were Stegosauria and Ankylosauria.

Stegosauria

Stegosauria was a group of armored dinosaurs that had rows bony of plates running along their backs. Stegosaurus is the best-known Stegosaurian, but several other genera have been discovered.

Example Stegosaurians

• Stegosaurus
• Hesperosaurus
• Wuerhosaurus
• Kentrosaurus

Ankylosauria

Ankylosauria was a group of armored dinosaurs that lived throughout the Mesozoic era. They were large, powerful, four-legged animals. All were heavily armored, and some developed tail clubs which may have been used as defensive weapons against predators. Ankylosaurus is the best known dinosaur in this group.

Example Ankylosaurians

• Ankylosaurus
• Minmi
• Polacanthus
• Edmontonia

Ornithopoda

Ornithopods were a branch of Ornithischian dinosaurs that appeared in the mid Jurassic period and lived to the end of the Cretaceous. They had three-toed feet, beaks, and an advanced (for a dinosaur) chewing ability.

Hadrosauridae (Duck-Billed Dinosaurs)

Hadrosaurids are also known as ‘duck-billed’ dinosaurs on account of their wide mouth parts. Hadrosauridae is a family of ornithopods descended from the Iguanodontians. Many Hadrosaurids were able to walk on both two and four feet, using all four feet when grazing, but using two feet to run.

Example Hadrosaurids

• Hadrosaurus
• Edmontosaurus
• Parasaurolophus
• Lambeosaurus

Pachycephalosauria (Marginocephalia)

Pachycephalosauria was a type of dinosaur that lived in the Late Cretaceous period. Pachycephalosaurians were bipedal and had thick skulls (the name Pachycephalosauria means ‘thick headed lizards). Many members of this group had domed skulls, which often had spikes.

Pachycephalosaurians may have fought each other by ramming their heads together – similar to the way in which deer stags fight to establish dominance within a group.

An example is Stegoceras, a small bipedal dinosaur with a domed head.

Example Pachycephalosaurids

• Pachycephalosaurus
• Stegoceras

Ceratopsia (Marginocephalia)

Ceratopsia means ‘horned faces’. This group of dinosaurs became common in the Cretaceous period and were found in North America, Europe and Asia. Like all Ornithischians, Ceratopsians were herbivorous. They had beaks, and ranged in size from 1 meter (3.3 ft.) to 9 meter (30 ft.) long, 9 tonne giants.

The best-known Ceratopsian was Triceratops, a large, powerful quadruped that had three distinctive spikes on its face and a bony frill at the back of its head.

Example Ceratopsids

• Centrosaurus
• Psittacosaurus
• Triceratops

Types Of Dinosaurs: Conclusion

When learning about dinosaurs, it’s important to remember that they were on Earth for tens of millions of years longer than humans have been.

This gave the dinosaurs plenty of time to branch off and evolve into different types of dinosaur. Dinosaurs had been appearing and becoming extinct for millions of years before the mass extinction event at the end of the Cretaceous period.

Like all living animals, dinosaurs can be classified into different groups. However, our entire knowledge of dinosaurs stems from fossilized remains that have been in the ground for an almost unimaginable length of time.

This is why, as we unearth more and more fossils, our understanding of dinosaurs, and the relationship between different types of dinosaurs, is continuously changing.