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The dinosaur’s era traces back to around 230 million of years. The story of this group of giant reptiles covers the whole Mesozoic era, which is divided in three different time periods: the Triassic, the Jurassic, and the Cretaceous period. During their existence, dinosaurs were divided into different species with various heights and shapes.
The result of this diversification lead to species classified according to two big food regiment categories: herbivores and carnivores. Dominating the earth up to the air, these reptiles never ceased to evolve. They are subdivided into two groups and are classified according to the structure of their pelvis.
Do you wish you would know more about the characteristics of this giants which disappeared at the end of the Cretaceous era? Do you wish to know everything there is to know about the two big families of dinosaurs? Find out their stories through this article about the different types of dinosaurs with pictures.
The term “dinosaur” means giant lizard, even if the height of certain species did not exceed one of a chicken. These sauropsid animals, who appeared at the Triassic period have dominated the Mesozoic era and were the result of a long evolution. Coming from former aquatics dinosaurs, climatic change was the biggest factor for their mutation.
These animals have transformed into a group of archosaurs, then this same group got divided into 3 different branches: crocodiles, pterosaurs and dinosaurs aka Dinosauria.
To distinguish Dinosaurias from other species, scientists had to draw up characteristics of their own:
Dinosaurs were sauropsids like reptiles or birds. These diapsids disposed of two temporal fosses on their skull, between their eye and their nostril.
Even if their name tells you these animals were giant lizards, some species like theropods, did not exceed 15 cm. For the biggest herbivores, in the contrary, like the diplodocus or the brachiosaurs, their height could go up to 50 meters.
Unlike lizards or crocodiles, some dinosaurs had a pelvic structure which allowed them to walk standing up. They had small hind legs and their ankles only had a simple articulation. Certain species were also equipped with a tail, big enough to maintain their balance.
Even if dinosaurs were considered like cold-blood reptiles or ectothermic, a lot of these animals could have had an endothermic metabolism, according to scientists. This hypothesis is still waiting to be confirmed and keeps being the subject of deeper research.
As the Dinosauria were sauropsid vertebrates, they all were oviparous and laid eggs in nests.
At its first appearance, every dinosaur was coming from bipedal carnivorous reptiles. So, they would only eat meat. But when the diversification happened during the Triassic and Jurassic period, species with a variety of food regiments appeared: herbivorous, piscivorous, frugivorous, insectivorous and folivorous dinosaurs.
Even if there are thousands of dinosaur species, in 1887, Harry Seeley succeeded to determine that these giant lizards could be divided into two different kinds. According to their pelvic bone structure, we can distinguish the Ornithischians and the Saurischians.
Also scientifically known as Ornithischia, these giant lizards with a bird pelvis had a rectangular pelvic structure. This characteristic explains the fact that, contrarily to Saurischians, their pubic bone was facing down.
In general, every Ornithischians was herbivorous, but some paleontologists have the hypothesis that certain species were probably omnivorous or partially carnivorous. What is sure is that they all got extinguished during their mass extinction.
As mentioned above, Ornithischians were herbivorous even if certain scientists are claiming the opposite. Considered as bird-type dinosaurs, a good number of these species belonging to this classification, had beaks.
Others, in the contrary, were equipped with a jaw adapted to plant mastication. Scientists succeeded to divide the Dinosauria Ornithischians into different subclades: thyreophorans, neoornithischians and Marginocephalia.
The more detailed we are, the more we discover that dinosaur species were not limited to diplodocus, triceratops, or T-rex. Other species existed and belonged to a sub-clade of thyreophorans. Of all the different dinosaur species, these were the least popular. However, they were among the most resilient and dreaded species, even as herbivorous.
The thyreophorans englobe bipedal and quadrupedal dinosaurs of various sizes. However, they had a common characteristic: the possession of a back armor. That is the reason why they were called thyreophorans, which literally means, “shield carrier”. These shields were spines or bone plates depending on the specie. Here are some dinosaurs representing the thyreophorans:
Stegosaurus is a specie that existed 150 million years ago. Its measurements were impressive with its 9 meters of length and 4 meters of height. It was also distinguished by its 17 bone plates lying on his back. This gave it its name of “roofed reptile”. 4 spikes also equipped its tail to defend itself against carnivores attacking them such as the Tyrannosaurus Rex. Weighing around 3 tons, the stegosaurus was feeding on plants.
From the big Stegosauria family, the stegosaurus is without doubt, the most well-known. Nevertheless, scientists have discovered more than one type of stegosaurus. We can cite as examples: the Hesperosaurus, the Kentrosaurus or the Wuerhosaurus.
Ankylosaurus was an armored dinosaur, which lived around the end of the Cretaceous era, around 70 million years ago. Ankylosaurus aka “the rigid dinosaur” after its French meaning, was a specie that lived close to rivers and swamps. It was characterized by its defensive armor made of spines and bone plates which went from the skull and into its back. In addition to this, it had a tail garnished with a sort of hammer.
Nodosaurus was one of ankylosaurus’s cousins. It lived during the inferior Jurassic era and was almost five meters long. These machines were equipped with a heavy armor, from the head to the tail. The osteoderms, which ran through their back, were big and pointy to scare their predators. Thanks to their robustness, the Nodosaurus specie lived until the Cretaceous era.
The second Dinosaurio Ornithischians subclade regroups neornithischians.
With thyreophorans, neoornithischian dinosaurs are part of the ornithischian’s classification. This subclade is composed by a Dinosauria group with teeth sharped as a blade, and with a resilient enamel. These species were the hard plants specialists.
It is important to know that the neornithischian group was very diverse. It also included numerous species, the most famous were:
Please know beforehand that, in the neornithoschian group, there is a lower clade known as ornithopoda. Iguanodon is the most know specie of this category.
This dinosaur was one of the most vigorous, with its powerful hind legs and his jaw capable of tearing plant away from the soil along with their roots. Being 10 meters long, Iguanodon was a large-scale animal even if its upper limbs were small.
Parasaurolophus is one of the most famous specie within the Hydrosauridae, which means duck-billed dinosaur. Descending from Iguanodontians, hydrosauridae all had a large buccal part and usually walked on two paws. They also used their upper limbs to graze.
Finally, here is the description of last subclade of the Dinosauria Ornithischians:
Marginocephalia is a part of the third subclade of Dinosauria Ornithischians. These ornithischians are distinguished by their skull. Depending on the specie, the skull bone formation could vary. Here are two of the most know ones.
Pachycephalosaurus as the rest of the Pachycephalasauria clade or “thick-headed dinosaur”, was characterized by their cranial dome, garnished with spikes. They used them to attack one another or to defend themselves from carnivores. Like musk ox do, nowadays. These bipedal herbivorous ornithischians lived during the superior Cretaceous period.
Belonging to the Ceratopsia subclade triceratops or “three-horned face”, were one of the most famous and common dinosaurs in the Cretaceous period. Fossils have been found almost everywhere in Europe, Asia, and North America.
This specie was characterized by its large bony frill and its three horns on the skull. Like a majority of onithischians, triceratops also had a beak-shaped mouthpiece and was herbivorous. As of its measurements, it was a quadrupedal animal who was between 1 and 9 meters long.
The second sort of classified dinosaurs according to their pelvis is the Saurischians.
Scientifically known as Saurischia, these dinosaurs had a similar bone structure to lizards, which means they had a three-pronged pelvis. Their pubic bone was facing their skull and their pelvis was triangular going down and forward.
Saurischians could be as carnivorous or herbivorous, and they did not all disappear during the third mass extinction. According to scientists, some species have survived and could be ancestors to the birds and raptors we see today.
Saurischian dinosaurs include species whose dorsal structure were like lizards. In this category, scientists included almost every giant carnivorous reptile and some herbivorous. Nevertheless, Saurichia is distributed into two distinct groups: theropods and sauropodomorphs.
Theropods were bipedal dinosaurs, which means they were walking on their hind legs. Most of them were carnivorous, and almost all of them had blade-shaped teeth, which gave them the name of “sharp teeth”. Later, they evolved and herbivorous and omnivorous theropods appeared.
Theropods appeared at the end of the Triassic period and lasted until the Paleogene period, which ended the reign of all giant reptiles. But scientists have proven that the mass extinction did not end their existence as some species of the group evolved into birds.
Besides, ostriches possess the same characteristics as these reptiles with their three functional fingers, as well as their hollow bones. That is also the reason why these birds are so fast and agile.
The evolution of the flying dinosaur tof the Theropoda subclade, lead to every species of flying reptiles. We can distinguish three main kind of theropods: Coelurosauria, Deïnonychosauria, and Carnosauria.
The superfamily of Coelusauria belongs to the theropod clade. These species were divided into different branches which, themselves, composed different families: Coelophysidae, Coeluridae Compsognathidae, Ornithomimidae, Oviraptoridae, Deinocheiridae, Saurornithoidides, Troodontidae, and Segosauridae.
Coelurosaurs, from the Greek meaning “hollow-tailed lizards” was a group of dinosaurs with a bird-resembling anatomy. Paleontologists also thought that most of coelurosaurs possessed feathers.
The second type of theropods is Deinonychosauria.
Deinonychosauria theropods formed the Dromaeosauridai super family, commonly named “raptors”. Velociraptors and microraptors are one of the best-known species in this category.
Velociraptors arose 75 million years ago, and had for nickname “agile thief”, thanks to their rapidity. They were small carnivorous bipeds, whose size did not exceed 75cm high unlike what we see in movies such as Jurassic Park or Jurassic World. Its height was about 1.5m or 2m and their lower limbs were longer compared to the rest of their body.
Velociraptorsalso had a retractable claw on their hind legs, which was very useful to catch their prey. Their tail was also covered with bone tendons, maintaining their balance and endurance. For information, Velociraptor’s top speed was 40km/h, not 100km/h like its portrayed in some movies.
Very recently, paleontologists have discovered that every velociraptor was entirely covered with feathers.
Microraptors were small dromaeosaurids that closely looked like birds. Only, they possessed numerous characteristics specific to dinosaur. Their teeth were pointy, and their tail ended with a fan of feathers. Their hind legs were also covered with feathers which let us think they had four wings. By its measurement (40-80 cm long), microraptor is considered today as one of the smallest dinosaurs to have ever existed.
Although we thought they were insectivorous, it turns out they could have also eaten meat. The presence of pretty big bone rings in this reptile’s eyes lead scientists to think they probably were nocturnal creatures. But numerous researchers have taken the hypothesis that microraptors were as active during the day and were hunting as a group.
The third and last type of theropods is the big group of Carnosaurs.
In the Carnosauria superfamily, you will find the Abelisauridae, the Tyrannosauridae, the Spinosauridae, The allosauridae and the Carchorodontosauridae families. Here is their respective description:
Abelisauridae is a big family of theropods that lived on continents like Asia, South America, and Africa. However, researchers could only find fossils belonging to them in India, Gondwana and Madagascar. These Dinosauria have survived until the end of the Cretaceous period. From the abelisaurid group, the most well-known species are the Carnotaurus and the Abelisaurus.
Carnotaurus or Sastrei Carnotaurus from its scientific name, was a vertebrate from the Saurischian clade belong to the abelisaurid family. Like the famous T-Rex, the Carnotaurus was a dreaded predator but T-Rex and Carnotaurus have never crossed paths, according to scientists. This explains the fact that Carnotaurus has occupied South America while the T-Rex occupied Asia and North America.
When it comes to measurements, sastrei carnotaurus was between 8 to 9 meters long and 4m high. Their upper limbs were atrophied like the tyrannosaurus and they had 4 fingers. Like the vast majority of Abelisauridae, carnotaurus had big facing forward eyes, which gave them a binocular vision. To this, adds quite large horns, which gave it its name of “carnivorous bull”.
Abelisaurus or Abel’s lizard was a bipedal reptile whose size could reach up to 9 meters long. This animal has lived in Argentina during the Cretaceous period and was also connected to theropods which lived during the Jurassic period. Like Carnotaurus, abelusaurus also had long hind legs and short upper limbs. One essential thing there is to know about the Abel lizard, is that, until today, only one specimen has been found by paleontologists.
From its name “tyrant lizard”, it was probably one of the most dreaded species. Tyrannosauridae was a carnivorous dinosaurs which was characterized by its gigantic skull and extremely powerful jaws. Most famous of all, are the T-Rex and Tarbosaurus.
It is undoubtedly, the most studied dinosaur by experts. This predator reigned as a king during the entire Cretaceous period, before disappearing during the mass extinction. T-rex had long clawed feet which measured more than 20 cm. From its 13 meters high and with its 8 tons of muscle, tyrannosaurus did not back down to anything, not stegosaurus, nor triceratops.
Tarbosaurus is a close cousin from tyrannosaurus and has the same characteristics. Bipedal, tarbosaurus had small upper limbs which ended with two fingers, unlike sastrei carnotaurus. Their massive skull could reach two meters long. Its only difference with T-Rex was that it would also scavenge when the opportunity came along.
Spinosauridae was a reptile characterized by a slim and long skull like crocodiles. Even though they were considered like undisputable predators, some members of this group like Baryonyx or Spinosaurus was piscivorous. Spinosauridae was also distinguished by its big dorsal sail. Its body was supported by spine-shaped bones. Which is why spinsauridae is named “spined reptiles”.
Allosauridae was a predator which made its first appearance at the end of the Jurassic period. These carnivores were dreaded for their gigantic sizes that could get to 10 meters high. The most well-known allosauridae was allosaurus.
It possessed a skull measuring up to 90 cm which presented many bone cavities, Saurophaganax was also from the big allosauridea family.
The biggest carnivores having lived on earth are without the doubt, from the carcharodontosauridae family. These giants measured up to 6 meters high and 15 meters long. They were also known for their numerous sharped teeth.
For this reason, these reptiles had for nickname “shark-toothed lizards”. The list of different carcharodontosauridae is a long one but among the most famous species, you can find: giganotosaurus, mapusaurus, and tyrannotitan.
The second Saurischian group is the saurodomorphs.
Sauropodomorphswere bipedal or quadrupedal. They were all herbivorous. Unlike to theropods, saurodomorphs had a small head, a long neck, and a tail longer than any other species. These dinosaurs, like most herbivores we see today, lived among a herd. Many sauropods reached a gigantic size. Their barrel-shaped bodies were typical of their specie.
The big saurodomorph family is subdivided into two big groups: diplodocidae and titanosauria.
From the diplodocidae family, diplodocus was the most famous even though apatosaurus, brontosaurus and supersaurus were also a part of the group. All these dinosaurs had a similar taxonomy with a long body which could reach 30 meters.
Titanosaurs appeared very early on during the Cretaceous period. They lived until the Mesozoic period. Like their name gives it away, these titanic dinosaurs were the biggest dinosaurs that we know of, today.
This sauropod group included Argentinosaurus and Paralititan. Unlike diplocidae, totanosauria had a small neck and tail and could use them as a whip. They also had a large pelvic girdle, which gave them a large posture.
Conclusion:
All this knowledge concerning dinosaurs was acquired by paleontologists and scientists through fossils. As things progresses and other fossils are found, dinosaur’s classifications and relations could still possibly change.
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