Dinosauria: A Comprehensive Guide to Terrible Lizards

Leave a comment / / Updated on: 21st December 2023


The Dinosauria superorder is a group of predominantly enormous reptiles between 231 and 65 million years ago, during the Mesozoic Era.

Dinosaurs dominated the Earth for over 165 million years and witnessed several significant evolutionary changes.

The term “Dinosauria,” or “terrible lizard,” was first used by Sir Richard Owen in 1842 to describe the Megalosaurus, Iguanodon, and Hylaeosaurus, as they were the only dinosaurs known at the time.

Other famous dinosaurs include the Tyrannosaurus rex, Triceratops, Stegosaurus, etc.

The word Dinosauira has Greek roots, and as mentioned, it is commonly translated as “terrible lizard.”

However, upon the coinage, Owen refers to dinosaurs as fearfully great, recognizing their enormous size, which exceeds that of any extant reptile.

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At the time, paleontologists tried to estimate the size of dinosaurs by scaling up modern lizards, even though the fossilized skeletons were far from complete.

These enormous sizes didn’t sit well with Owen. Instead, he counted each vertebra individually and calculated their overall number using those of living crocodiles.

Although many members of the Dinosauria superorder were huge, dinosaurs were diverse animals with different body sizes, shapes, and features.

Some of the most notable characteristics of dinosaurs include their bipedal stance, bird-like or lizard-like hips, and sharp teeth and claws.

This article will provide an overview of the Dinosauria superorder, including their classification, evolution, characteristics, and extinction.

Characteristics of the Dinosauria Superorder

Although the Dinosauria superorder was a diverse group of reptiles that exhibited various characteristics, some of the animals under this group shared certain standard features; here are a few of them:

1. Bipedalism

Bipedal Dinosaur | CoreyFord via Getty Images

Most dinosaurs were bipedal, meaning that they walked on two legs.

This was due to the evolution of strong hind legs and a shift in the center of gravity towards the hips, allowing for better balance and mobility.

The earliest dinosaurs were small and walked on all fours, much like their reptilian ancestors.

However, some dinosaurs began to walk on two legs, and this change in posture and locomotion would affect their anatomy and behavior.

While other scientists continued to use lizards as a model when dinosaurs were initially discovered, with legs that protruded from the sides of their bodies, Owen was sure that the animals’ legs would have been directly under their bodies to maintain their enormous sizes.

He portrayed them in a manner and scale that is close to that of contemporary quadrupedal mammals.

In bipedal dinosaurs, the center of gravity shifted towards the hips, which allowed for better balance and stability.

The structure of the pelvis, legs, and foot subsequently changed as a result.

Bipedal dinosaurs had longer, more vertically positioned pelvises, which helped them maintain balance and support when standing and walking.

Dinosaurs with bipedalism also had extremely specialized feet.

Their elongated toes could grip the ground, providing better running and jumping traction.

Due to the ankles’ high degree of flexibility, they had more motion range and shock absorption.

2. Scales and feathers

Feathered Dinosaur, Microraptor | MR1805 via Getty Images

While some dinosaurs had scales, others had feathers.

The keratinized substance that makes up scales is tough and protects the skin.

Several reptiles have scales covering their entire bodies, including crocodiles and lizards of today.

Many dinosaur species also had scales. While some of the scales on dinosaurs were small and rounded, others were bigger and more elongated.

Feathers, on the other hand, are made of a softer, lightweight protein called keratin.

They evolved from scales and likely served several functions in dinosaurs, including insulation, display, and flight.

Feathers come in many shapes and sizes, ranging from simple, hair-like structures to complex, branching feathers in modern birds.

3. Teeth

Tyrannosaurus Teeth | wwing via Getty Images

Teeth were a crucial feature of dinosaurs for feeding, defense, and communication.

Dinosaurs had diverse teeth, ranging from flat grinding surfaces to sharp, serrated blades.

The study of dinosaur teeth has provided significant insights into their diets, behavior, and evolution.

The structure of dinosaur teeth can vary greatly depending on the species and diet.

Herbivorous dinosaurs had teeth with broad, flat surfaces for grinding plant material.

These teeth were often arranged in rows or batteries for efficient food processing.

Carnivorous dinosaurs had teeth that were sharp and serrated, designed for tearing flesh.

These teeth were often curved and pointed, enabling them to puncture and grip their prey.

4. Posture

Dinosaurs and a meteor falling from the sky in the back background | ugurhan via Getty Images

Posture is one of the most defining characteristics of dinosaurs.

Dinosaurs had a unique upright posture, with their legs positioned directly underneath their bodies.

They attained exceptional sizes and weights because of this posture, which improved their ability to move and supported their body weight better.

The environment of a dinosaur was one of the main determinants of its posture.

Moving quickly and seeing predators from a distance made bipedalism more useful in open areas.

Quadrupedalism was preferable in woody areas because it gave better stability and maneuverability.

5. Reproduction

Model of a dinosaur egg. | Xenophon via Wikipedia (CC BY-SA 3.0)

Most dinosaurs were oviparous, which means that they laid eggs.

Dinosaurs lay their eggs in nests, often made of plants and other elements of the local environment.

Despite some dinosaur species perhaps having built nests in trees, the nests were frequently found on the ground.

It is unclear to what degree dinosaurs showed parental concern.

However, there is evidence that some dinosaur species may have practiced parental care behaviors.

For instance, fossilized nests have been discovered that contain both adults and youngsters, indicating that the adults may have looked after and safeguarded their young.

The fact that some dinosaur species were discovered in a brooding posture further supports the idea that they may have incubated their eggs.

6. Social Behavior

Triceratops Herd | dottedhippo via Getty Images

Recent research has suggested that some dinosaurs were much more social than previously thought.

The finding of massive bone beds comprising the remains of several members of the same species provides the first evidence of social activity in dinosaurs.

These bone beds imply they may have coexisted in herds to avoid predators or migrate.

Trackways are another source of proof supporting social activity in dinosaurs.

There have been instances where dinosaur footprints have been discovered in groups, indicating that these animals were traveling together.

In other tracks, there is evidence of individuals walking side by side, which might be a sign of herding behavior.

Timeline of The Dinosauria Superorder

The Dinosauria superorder lived on Earth for over 160 million years.

The Triassic, Jurassic, and Cretaceous periods make up the main divisions of the Dinosauria superorder’s period.

Each period saw the appearance of new dinosaur species and their final extinction.

1. Triassic Period (251-199.6 million years ago)

Triassic Era | ilbusca via Getty Images

The Triassic period marked the emergence of the Dinosauria superorder.

Dinosaurs first appeared during the middle of the Triassic period, around 230 million years ago.

They evolved from a group of reptiles known as archosaurs, which also gave rise to crocodiles, pterosaurs, and many other creatures.

The earliest dinosaurs were small, bipedal animals living in various environments, including forests, plains, and river valleys.

Some early dinosaurs that lived during this period include Eoraptor, Coelophysis, and Plateosaurus.

These animals were probably carnivorous and likely preyed on small reptiles and insects.

A global extinction catastrophe, estimated to have occurred 201 million years ago, heralded the end of the Triassic period.

Several variables, including volcanic activity, climate change, and asteroid strikes, are thought to have contributed to this occurrence.

Several species, including some dinosaurs, were wiped out, and it greatly impacted life on Earth.

2. Jurassic Period (199.6-145.5 million years ago)

Stegosaurus on top mountain | FOTOKITA via Getty Images

Larger and more varied dinosaur species evolved throughout the Jurassic period.

Because so many fossils from this era have been discovered, it is regarded as the “Golden Age of Dinosaurs.”

Jurassic-era dinosaurs included some of the most well-known species, including Stegosaurus, Brachiosaurus, and Allosaurus.

The earliest birds likely descended from tiny, feathered dinosaurs during this time.

3. Cretaceous Period (145.5-65.5 million years ago)

Velociraptor walking through the forest | Orla via Getty Images

The Cretaceous Period was the final period of the Mesozoic Era, lasting from 145.5 to 65.5 million years ago.

During this time, the Earth was home to a diverse array of dinosaurs, ranging from the largest herbivores to the most fearsome carnivores.

The dinosaurs continued to evolve and diversify, with new species emerging, such as Triceratops and Tyrannosaurus rex.

However, the end of the Cretaceous period also saw the extinction of the non-avian dinosaurs, likely due to a combination of factors such as a large asteroid impact and volcanic activity.

Non-avian dinosaurs went extinct, and new animal species, including mammals and birds, began to appear on the planet.

It is believed that small, feathered dinosaurs that survived the extinction event gave rise to birds.

Today, birds are the only surviving members of the Dinosauria superorder.

Major Organism Groups of the Dinosauria Superorder

The Dinosauria superorder is divided into two orders: Ornithischia and Saurischia.

1. Ornithischia Order

Ankylosaurus and Triceratops from the Ornithischia Order | Orla via Getty Images

As mentioned, the Ornithischia order is one of the two primary orders of the Dinosauria superorder.

The distinguishing feature of this order is their unique hip structure, which resembles modern birds.

Alto, the dinosaurs that fell under this order were herbivores.

They had jaws that resembled beaks and frequently had rows of teeth arranged like dental batteries.

They could grind vegetation more effectively thanks to these batteries.

Certain ornithischians also had unique features like cheeks that retained food during chewing.

The Ornithischia order encompasses several significant subgroups or clades, each with distinctive features and evolutionary history.

Some of the most notable subgroups include Thyreophora, Marginocephalia, and Ornithopoda.


Ankylosaurus on a dry land | ALLVISIONN via Getty Images

The Thyreophora suborder is a group of interesting species that existed roughly 200 and 65 million years ago during the Mesozoic Era, specifically the Jurassic and Cretaceous periods.

The suborder is renowned for its unusual defensive adaptations, including numerous kinds of body armor.

This armor had several features, including bony plates, spikes, and thickened skin.

The most famous members of the Thyreophora suborder include the Ankylosauria and Stegosauria groups.

Dinosaurs under the Ankylosauria group were strongly armored, low-slung creatures with powerful limbs.

They had osteoderms, bony plates embedded in their skin all over their bodies.

On these dinosaurs’ backs, flanks, and tails, these osteoderms created a barrier of defense.

In addition, some Ankylosauria dinosaurs had tail clubs—vast bone masses utilized as a weapon against predators—at the end of their tails.

On the other hand, the Stegosauria group possessed recognizable rows of bony plates and huge spikes along their backs.

Double rows of these plates, often called osteoderms or dermal plates, ran the length of the dinosaur’s back.

They served as heat dissipators and temperature controls. Paleontologists still disagree over the function of the massive spikes, or thagomizers found at the end of the tail.

While some hypotheses contend they served as protective tools against predators, others contend they might have helped in intraspecific conflict or display.


Group of triceratops walks in the valley | ALLVISIONN via Getty Images

The Marginocephalia suborder is a diverse group of herbivorous dinosaurs with distinctive bony crests or domes on their skulls.

Marginocephalians lived during the Mesozoic Era, specifically in the Late Jurassic and Cretaceous periods, approximately 161 to 65 million years ago.

Marginocephalia is divided into two main infraorders: Pachycephalosauria and Ceratopsia.

Pachycephalosaurs were small to medium-sized dinosaurs known for their thickened skulls and dome-shaped cranial structures.

They might have moved on two legs, as evidenced by their long hindlimbs and short forelimbs.

The Late Cretaceous period is when pachycephalosaurs are primarily known, and their fossils have been discovered in North America, Asia, and Europe.

The unique skull decorations of ceratopsians, which included horns and frills, set them apart from other quadrupedal dinosaur species.

They are called “horned dinosaurs” and were widely distributed in the Late Cretaceous. In North America and Asia, ceratopsians predominated.

Ceratopsidae (large-finned dinosaurs) and Protoceratopsidae (smaller-frilled dinosaurs) are the two further branches that make up this group.


Iguanodon dinosaur walking in the desert by day | Elenarts108 via Getty Images

The Ornithopoda order represents a diverse group of herbivorous dinosaurs during the Mesozoic Era.

They were a highly successful and widespread group known for their unique adaptations and evolutionary innovations.

Ornithopods exhibited unique characteristics that allowed them to adapt to different environments and feeding strategies.

Their dental configuration was one of their distinguishing characteristics. They had rows of closely spaced teeth at the back of their jaws to effectively grind tougher plant matter.

Ornithopods also moved mainly on two legs, although they could switch to four legs when necessary.

They had powerful tails and lengthy hind limbs, which helped with balance and stability when moving.

2. Saurischia Order

Tyrannosaurus Rex, a Saurschian dinosaur | Warpaintcobra via Getty Images

One of the two major orders of the Dinosauria superorder, the Saurischia order, contains a wide variety of dinosaurs that dominated the Mesozoic Age.

Theropoda and Sauropodomorpha are the two primary subgroups of Saurischian dinosaurs, which were distinguished by their lizard-like hip structure.

Notable Examples of Organisms within the Dinosauria Superorder

The Dinosauria superorder encompasses a remarkable array of prehistoric animals that ruled the Earth for millions of years.

These prehistoric animals, which ranged in size from massive predators to armored herbivores, have permanently altered our view of Earth’s past.

A few well-known dinosaurs from this diverse group have caught the interest of people worldwide.

Here are a few of them:

Tyrannosaurus Rex

Tyrannosaurus rex fight in the valley | ALLVISIONN via Getty Images

Also known as T. rex, it was a massive carnivore that inhabited North America during the Late Cretaceous era and is one of the most well-known and terrifying dinosaurs.

The T. rex, with lengths up to 40 feet and heights exceeding 15 feet, is renowned for its enormous size, strong jaws, and razor-sharp teeth.

It is thought to have been one of the greatest terrestrial predators.

T. rex is frequently recognized as the top predator of its era due to its powerful bite and sturdy physique.


Stegosaurus | Daniel Eskridge via Getty Images

The herbivorous dinosaur Stegosaurus is distinguished by a row of erect plates running the length of its back and by a collection of pointed, spiky tail bones known as a thagomizer.

This dinosaur lived during the Late Jurassic epoch in North America.

It had a brain about the size of a walnut and a little head with a mouth like a beak.

The Stegosaurus’ plates are thought to have been used for show or thermoregulation, and its spiked tail was probably a defensive adaption.


Triceratops | xijian via Getty Images

The well-known herbivorous dinosaur Triceratops existed in the Late Cretaceous epoch.

With three facial horns, a massive bony frill, and a substantial body, this dinosaur is known for having a striking appearance.

Triceratops used their horns to protect themselves from predators and perhaps to settle territorial conflicts.

Before the catastrophic extinction that killed off the majority of dinosaur species, it was one of the last non-avian dinosaur species to have lived.


Diplodocus | Warpaintcobra via Getty Images

Diplodocus was a herbivorous dinosaur that existed between 154 and 150 million years ago during the Late Jurassic period.

This dinosaur was distinguished by its long neck and tail, which accounted for the majority of its body length.

Diplodocus likewise had a small head and a small brain, but it was able to travel on four legs because of its enormous, powerful body.


Around 76–73 million years ago, during the Late Cretaceous epoch, the herbivorous dinosaur Parasaurolophus existed.

It was easy to identify this dinosaur by the unusual crest on the rear of its skull, which was probably employed for display and communication.

Moreover, Parasaurolophus possessed a long, tubular snout and a bill that resembled a duck for eating plant matter.

Extinction Event that Caused the Disappearance of the Dinosauria Superorder

Asteroid falling from the sky | serpeblu via Getty Images

The extinction of the Dinosauria superorder is one of the most fascinating and enduring mysteries in the history of life on Earth.

For over 165 million years, dinosaurs dominated the planet, but around 65 million years ago, they completely disappeared.

Although several minor extinctions happened before the final one, the others were not as devastating.

This event, known as the Cretaceous-Paleogene (K-Pg) extinction event, marked the end of the Mesozoic Era and the beginning of the Cenozoic Era.

It is generally accepted that several events, including volcanic activity, climate change, and a strange impact event, contributed to the K-Pg extinction event.

The most well-known explanation contends that an asteroid or comet collision was the primary cause of the extinction, as suggested by physicist Luis Alvarez and his colleagues in 1980.

Following the early 1990s discovery of the Chicxulub crater off the Yucatan Peninsula in Mexico, this explanation was widely accepted.

The impact, which had a diameter of approximately six miles (10 kilometers), discharged tremendous energy and brought about a global calamity.

Massive shockwaves caused by the impact would have set off earthquakes, tsunamis, and volcanic eruptions.

Large amounts of dust, ash, and debris were also ejected by the impact into the sky, obstructing sunlight and altering the climate on a worldwide scale.

This led to a scenario known as “nuclear winter,” in which the temperature plummeted, the amount of sunlight was reduced, and photosynthesis was severely hindered.

As a result of the lack of sunshine, the food chain collapsed, hurting both plant and animal life.

A string of disastrous effects were caused by the impact event’s aftermath.

Huge flames would have consumed entire areas, adding to the smoke and poisonous substances already present in the air.

Ecosystems would have been further destroyed by acid rain brought on by the emission of sulfur and nitrogen chemicals.

These elements worked together to cause an ecological collapse that wiped out numerous plant and animal species, including the dinosaurs.

Although the impact idea is generally accepted, several explanations for the extinction of the dinosaurs have been put forth.

An alternative theory contends that the extinction was significantly influenced by volcanic activity.

Active volcanoes with lava, green plants, cave, and silhouette of dinosaurs on a blue sky | NatuskaDPI via Getty Images

Modern-day India’s Deccan Traps, a sizable volcanic area, was undergoing massive eruptions throughout the late Cretaceous period.

Large volumes of greenhouse gases, including carbon dioxide and methane, were released into the atmosphere as a result of these volcanic eruptions, accelerating climate change and global warming.

According to this idea, the planet’s ecological stress was compounded by the interaction of volcanic activity and the impact of an asteroid, which caused the extinction of the dinosaurs.

Additionally, there are hypotheses proposing that gradual changes in sea level, fluctuations in oceanic temperatures, or disease outbreaks contributed to the extinction event.

However, these theories have received less support compared to the impact and volcanic hypotheses.

In conclusion, the extinction of the Dinosauria superorder is believed to have been caused by a combination of factors, with the asteroid impact event being the primary catalyst.

The K-Pg extinction event marked a significant turning point in the history of life on Earth and allowed for the rise of mammals and other new groups of organisms to dominate the planet in the Cenozoic Era.


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