Tom was a very curious teenager who loved animals and exploring the wilderness. He would often be seen camping outdoors with his buddies. One day while camping in a forest, he happened to bump into a woman who seemed to be fidgeting with a device that looked identical to a spaceship. Being a curious kid, Tom asked the woman, “what are you doing, ma’am?”
The woman was startled by Tom’s presence. “Hey, you scared my guts.” Tom said, “Calm down, I won’t bite.”
“Ha, you are a cheeky guy indeed; I see that you are holding the action figure of a T-rex in your hand. Do you want to know about the dinosaurs?”
Tom’s face lit up with excitement, and he sported a wide grin, “Yes, sure, I would love to.”
“That’s great; dinosaurs were one of the largest and the most magnificent creatures that roamed the Earth over 66 million years ago. Let’s take a dive into ancient Earth and get to know the long-extinct creatures thrived on this planet and understand their way of life.” This sparked Tom’s curiosity; he introduced himself and asked the lady again, “Hey, what is this device?”
The woman said, “Hi Tom, I am Stella, an engineer and the device you see here is a time machine; let’s hop on and meet the dinosaurs.” Whoa, this is so awesome Stella, I would love to see the dinosaurs and learn more about them.”
Tom and Stella entered the time machine, where they met a man.
“Hey there, my dear friend, I am Paul, a palaeontologist and paleobiologist who has been long studying dinosaurs for over 15 years. I would like to introduce you to some of the most popular dinosaur species that have lived in the Mesozoic era, which was between 256 to 66 million years ago. Are you ready for the journey?”
Tom Shrieked with excitement, “Yay! This is going to be so cool.”
“Well then, what are we waiting for? Let’s hit the switch.” Paul sets the time to 150 million years into the past and hits the switch. The time machine soared high into the sky and vanished into thin air.
Meeting the Sauropods
“We are here,” said Stella. Paul nodded and said, “Let me take Tom outside and give him a tour of the surroundings.”
As Paul and Tom stepped out of the time machine, they were greeted by a heard of large dinosaurs feasting on leaves from a tall tree. Tom cried out, “That the Brachiosaurus!”

“Yes, Tom, that’s brilliant. Brachiosaurus is a species of sauropod dinosaurs that measure between 25 to 30 meters in length and are herbivores. They are long-necked four-legged dinosaurs with tiny heads and massive bodies with long tails. These long tails help them to balance properly, move and reach the leaves of tall branches. You might be wondering how these large animals would get enough oxygen to their brains. Sauropod dinosaurs had a system of air sacs and hollow cavities in most of their vertebrae. This air sac system helps them to reduce the weight of their necks and allow them to get enough oxygen.”
“Hmm, I see. Can you tell me their lifestyle, Paul”
“Sauropod dinosaurs like Brachiosaurus feed on plants and leaves on trees. They usually stick together and move as a large herd. Their hind legs are stronger than their front legs, thereby enabling them to reach higher branches and switch to a bipedal stance. While in a herd, they can use their front legs to fend off against predators. Even powerful carnivorous dinosaurs like the Carnotaur or the T-rex would not stand a chance against the crushing stomping power of a sauropod.”
“How many kinds of sauropods are there, Paul?”
“During the Jurassic and Triassic periods, there were many species of sauropod dinosaurs. Most sauropods had similar characteristics to the Brachiosaurs, but some were smaller, and a few were much larger. For instance, the Argentinosaurus was 10 meters longer than the Brachiosaurus. Some other popular sauropod dinosaurs are Apatosaurus, Vulcanodon, Mamenchisaurus, Shunosaurus, Barosaurus, and Nigersaurus. Some of these sauropods had longer necks, a slightly higher bone and muscle density with a little difference in skeletal structure. Also, all these dinosaurs that I mentioned didn’t live in the same region or the exact time; they lived a few million years apart as some evolved and adapted according to the environment.”

“This was really quite insightful, Paul; I can’t wait to see the carnivorous dinosaurs.”
Meeting the Theropods
Tom and Paul got into the time machine, set the date to 70 million years from the present and hit the switch. They landed in a region in South America in a relatively sub-tropical landscape. When they noticed two Carnotaurs hunting down a juvenile herbivore dinosaur, they stood rooted to the spot. Tom’s face lit with excitement, and he was about to shriek with joy when Paul shushed him and asked him to lay low.

Paul then explained about the Theropod dinosaurs, spoke of their hunting habits, their constituency, and lifestyle.
“Carnotaurs are a species of theropod dinosaurs that lived during the late cretaceous period, which was just before the mass extinction of the dinosaurs. They had a large build but highly agile predators who tend to hunt in packs. They have very small arms and are bipedal in nature. When compared to other theropod dinosaurs, Carnotaurs follow a strategy to hunt down prey tactfully.”
Tom asked Paul, “why do theropod dinosaurs like Carnotaurs have small arms and large legs?”
“Theropod dinosaurs have hollow bones, three-toed limbs, and are generally classified as a group of Saurischian dinosaurs. These dinosaurs are bipedal and mostly carnivores; they were built to remain agile and hunt for prey. Some popular theropod dinosaurs include the Tyrannosaurus (T-rex), Spinosaurus, Ceratosauria, Neotheropoda, Coelophysoidea, and Carnotaurus.

“Hmm, are there any common misconceptions with respect to theropod dinosaurs, Paul?”
“Of course, it is widely thought that the T-rex were lone hunters, they roar in high pitched voices, and they used to target and take down fully grown dinosaurs. All these are complete myths as the T-rex always hunted in packs of three or two, they made a low-pitched grunting noise and always preferred hunting juvenile dinosaurs as most fully grown dinosaurs were harder to take down.
Meeting the Ornithischians
Paul and Tom boarded the time machine and moved a few million years into the past to sometime around 100 million years ago. They landed in an area with rich vegetation somewhere in North America.
They noticed a few Stegosauruses taking a sip of water from a nearby pond. Tom asked excitedly, “Hey don’t they belong to the Ornithischians species of dinosaurs.”
“Yes, that’s right, Tom, now can you tell me more about these subspecies of dinosaurs?” asked Paul.
“Of course, Ornithischia or Ornithischians are a group of mostly herbivorous dinosaurs whose pelvic structure and resemble that of birds. They are known to adapt to different climatic conditions, reproduce in masses, and are partly covered in feathers during their juvenile years. However, it is debated among palaeontologists as to whether they had feathers or not. Their hips also resemble that of the birds we see today, like the ostrich, for instance. Some Ornithischians are quadrupedal, whereas some are bipedal. Most omnivorous Ornithischians are bipedal, but their medium-sized forelimbs make it easier to switch to a quadrupedal stance while waiting for prey and hunting.”

“Atta boy Tom, it looks like you have done your research. Well, there are a few things that you missed out on. Unlike Theropods and Sauropods, most Ornithischians species of dinosaurs differ in body structure, lifestyle, and physical characteristics. For instance, the Stegosaurs you see here lived during the Jurassic and early Cretaceous periods. They lived mostly in the northern hemisphere. They were armoured dinosaurs large in size, protected by spikes on their spine and had a broader pelvis. They were unable to run a high speed, but later evolved to Stegosauride, which had long legs that enabled them to run faster and had more resilient armour.”

“Wow, they were more like mini tanks of that time, I guess,” said Tom.
“Yep, and not to forget about the Triceratops, they were also a species of Ornithischians that came under the sub-species of Ceratopsians. They were predominantly herbivorous dinosaurs that had longhorns to fend off predators. However, not all Ceratopsian dinosaurs had horns, as some of them were smaller dinosaurs. Did you know that a fully grown Triceratops can take down a Carnotaur or even a Tyrannosaurus when confronted? Yes, if the Triceratops uses its horns to pierce the gut of a Tyrannosaurus, then the latter could bleed out and die.”

“Oh my god, Paul, I never knew that an adult Triceratops could take down the T-rex.”
“Yes, and also to note, some popular Ornithischians are Pisanosaurus, Ankylosauria known for their hard armour-plated back and a club on its tail, Pachycephalosauria is known for their hard heads, Scutellosaurus, and Ornithopods.
Meeting the Dinosaurs of the Sky
“Hey Stella, what say, shall we take the time ship up to the sky to show Tom some flying dinos?”
“Sure Paul, I would love to.”
The time ship soared into the sky and met the clouds. Paul asked Tom, “Hey young man, do you want to meet some winged reptiles?”
“Wow, would love to!” Tom shrieked with excitement.
As they were flying, they noticed numerous bird-like dinosaurs that flying by their side. Paul pointed out to a few of them and explained each species.
“The flying reptiles you see to the right are Pterosaurs, they were the most resilient creatures as they have stood the test of time quite well. They existed from the early Mesozoic era to the great extinction. Yes, that’s right they have survived for nearly 162 million years. They were the largest flying dinosaurs with a wing span of 10-11 meters and weighed up to 250 kilograms. While standing, they could reach the height of a modern giraffe. Their bones were hollow and air filled, similar to that of birds, with a large breastbone and an enlarged brain. Pterosaurs were intelligent enough to coordinate with their kind and engage in complex flying behaviour that helped in hunting for prey.”

“The flying dinosaurs you see to the far left are known as Microraptors. These dinosaurs are relatively small with four wings and are highly agile in air. Due to their small size, they can make sharp manoeuvres in quick succession and evade larger predators.”

“The ones you see a few feet below are the Sinornithosaurus. As you can see these dinosaurs are also relatively small with feathers and weigh only 3-4 kilograms. They are known for gliding and swooping down to catch small prey just like a modern eagle. According to paleo-research Sinornithosaurus might have had a venomous bite to neutralize prey. They were highly active dinosaurs as they remained vigilant both during the day and night.”

“This is sick Stuff Paul, looks like there is a lot more to research on when I get back to the present.” Said Tom.
Meeting the Dinosaurs of the Sea
Paul and Tom boarded the time machine, and Stella suggested that they use it as a travel ship to go underwater and see the dinosaurs at sea. Paul felt that this was a brilliant idea and urged Stella to go ahead. They travelled to the ocean.
Stella pressed a few buttons and flicked a few switches; the time machine transformed into a mini-submarine and dropped into the water. All were stunned by the amazing sight that they behold. There were numerous large marine creatures that swam hither thither. Tom was unable to identify most species and turned to Paul for help.
Paul said, “ Hey, look, Tom, Do you see that large fish-like lizard there?
“Yes, what is it?”
“Well, that is the Ichthyosaur; they are also known as fish lizards as they resemble large dolphin-like reptiles. They lived all through the Mesozoic era and evolved differently over a period of 100-150 million years, during the Jurassic, Triassic, and Cretaceous periods. Fossil evidence suggests that they first appeared around 250 million years ago. Ichthyosaurs evolved from a group of unidentified land reptiles that returned to the sea. This is seen in mammalian land-dwelling ancestors of modern-day dolphins and whales. They were a product of convergent evolution, that is the independent evolution of similar features in species of different periods of epochs in time.”

Just then, they spotted another dinosaur-like fish with a mouth identical to an alligator. Paul explained what creature that was.
“Hey, Tom, that’s a Pliosaur; if you observe closely, you will notice that they have crocodile-like short necks and large heads with massive toothed jaws. They are giant swimming reptiles and aren’t dinosaurs. They have an elongated head, large hind flippers and were predominantly carnivorous with long powerful jaws that had large conical teeth. Pliosaurs ranged from 4 to 15 meters in length.”

“Hmm, can you tell me about the Mosasaurs?” asked Tom.
“Hey Stella, can we travel to 70 million years in the past as we are now a 100 million years in the past?” Asked Paul.
“Sure thing Paul.” Said Stella
When they reached the same location 30 million years later, Tom was able to see the Mosasaurs. Paul explained.
“Mosasaurs were large marine reptiles that breathed air, were very powerful swimmers and were carnivores like most sea fearing dinosaurs. They adapted to living in warm, shallow inland seas and gave birth to live young rather than returning to the shore to lay eggs. They ranged between 5 to 13 feet long and had a body shape similar to monitor lizards. Their bite force was so powerful that it could take down the modern great white shark with just one bite.”

“Thanks a lot for your insightful explanation, Paul; I have learnt a lot about dinosaurs living in various environments.” I would love to meet you and Stella often and go on a wild exploration to different times in the past to understand different cultures, civilizations and people.”
Tom, Paul, and Stella returned back to the present, exchanged pleasantries and contact information and went their merry way. This experience had helped Tom to draft a new thesis for one of his school projects too.


















