Dinosaurs may be defined as archosaurs with hind limbs held upright under the body, based on one of the above definitions.
Pterosaurs, mosasaurs, ichthyosaurs, Plesiosaurs, and Dimetrodon are some of the other prehistoric creatures that are often confused with dinosaurs. Being members of the clade Ornithodira, pterosaurs are distant cousins of dinosaurs.
Except for Dimetrodon (which is a synapsid), the other taxa mentioned are Sauropsida (the reptile and bird clade). They didn’t have the upright hind limb stance of real dinosaurs, either.
Throughout the Mesozoic Era, dinosaurs, particularly the Jurassic and Cretaceous epochs, were the most common terrestrial vertebrates. Mammals, for example, were mostly rodent-sized carnivores of tiny prey that were confined in bulk and niches.
They have always been recognized as a highly diversified group of animals, with over 900 non-avian dinosaur genera having been identified with certainty by 2018 and the overall number of genera preserved in the fossil record projected to be around 1850, about 75% of which have yet to be found.
16 Living Creatures that Coexisted with Dinosaurs
Before an asteroid smacked the earth, dinosaurs had a successful run lasting more than 180 million years. Did it or didn’t it? (That’s a different matter.)
While the Cretaceous-Tertiary mass extinction (sometimes known as the K/T boundary) wiped out most life on Earth, several marine groups and land-based vertebrates survived.
Some of the creatures whose ancestors walked (or swam) alongside the most dangerous predators that ever lived are depicted in this film, which may give you an idea what life was like before and during the reign of dinosaurs.
Who do you think you’re calling chicken? The members of theropods, which include Tyrannosaurus rex, a strong predator, and Velociraptors, a smaller predator, are birds descended from a group of two-legged dinosaurs.
All its relatives must be massive and terrifying, right? The T-rex was one of the world’s largest and most fearsome creatures. It’s not quite that simple!
The powerful T-rex, according to fossil research, has a lot of DNA in common with modern-day chickens and, as a result, all birds. Now you’ll never think of a lowly pigeon in the same way again!
Crocodilians are the closest living relative of dinosaurs.
Did you know that crocodilian creatures were also abundant in the world 99 million years ago, as well as dinosaurs?
That’s correct, for an estimated 240 million years, the species has lived on Earth and even crocodiles have thrived. Indeed, huge crocs like Sarcosuchus, Dryosaurus, Deinosuchus, Shieldcroc, and others must have lived in the Cretaceous period. It must have been a scary time!
Several creatures you see today, including crocodiles, have significant links with dinosaurs, and their rubbery skin, sharp teeth, and hooked claws are all visible similarities!
We know that crocodilians like crocodiles and alligators share common ancestors with dinosaurs, so chickens may be the rightful descendants of dinosaurs.
To think that these creatures outlived the dinosaurs! Crocs as we know them today are actually very similar to their ancient predecessors from the Cretaceous period (circa 145-166 million years ago).
Snakes survived the extinction of the dinosaurs, just as crocodiles did. They survived the dinosaur era and lived to tell the tale, sliding their way out alive.
The snakes first emerged around 140 to 167 million years ago, right in the middle of the dinosaur period, when the enormous reptiles domajored on land as some of the fiercest and most dangerous predators.
They ate their young too, and they didn’t just live among dinosaurs!
We usually picture enormous animals roaming the Earth when we consider dinosaurs, but not every creature was that oversized. In fact, at ground level, there was a hive of activity, with snakes being one of the most common creatures we know today.
Snakes have survived millions of years of mass extinctions by somehow slipping their way out.
And finding several fossilized snakes over 140 million years old – that’s twice as long as Mr T-Rex – scientists can prove this.
Turtles, along with their relatives such as birds, crocodiles, and dinosaurs, are now considered to be members of the Archelosauria group.
Sea turtles developed around 110 million years ago, alongside dinosaurs. Sea turtles have existed in ancient times, and a genus of extinct sea turtles known as Archelon swam the seas some 80 million years ago.
We’re shell-shocked! Each of these creatures was nearly four meters long and five meters broad from flipper to flipper.
Even while the dinosaurs roamed the planet, buzzing bees were alive and stinging! They first arose during the Cretaceous epoch, sometime around the time when the first flowering plants began to bloom (give or take a few million years). They’re bee-lieved to have sprung up at that time.
We don’t know for sure how these honey-harvesting insects crossed the K/T boundary, but a 2013 study of carpenter bees suggests that bee populations suffered from a mass extinction as well.
Did you know that ostriches are closely related to a species of dinosaur that lived during the late Cretaceous period, and are often regarded as whacky-looking creatures? Ostriches do have a dinosaur-like appearance, so this makes sense when you think about it.
They have talons that are claw-like and are roughly the same size and form as those of a number of dinosaur species, including the well-known velociraptor.
This magnificent bird has walked the Earth for more than 66 million years and is now native to Africa’s plains. It has weathered a number of extinction events.
Did you see this one coming, or what? These nightmares-inducing oceanic predators have been in the oceans for almost 450 million years, predating even the advent of dinosaurs and surviving four of the five major extinction events!
They were most likely prey to the massive Spinosaurus aegyptiacus during the Cretaceous period, but they flourished and spread once the dinosaurs died out.
(Would you like to swim with some of these ferocious fish?) For beginning shark-diver, check out our PADI-recognized discovery scuba dive.)
Sharks are more than 450 million years old, and they do not resemble your typical dinosaur.
As a result, the sharks we know today are descended from species that lived millions of years before dinosaurs existed. To comprehend is almost impossible.
Sharks have certainly evolved over time, and they have grown in size as well. Sharks used to be substantially bigger, with the megalofor, the biggest known species, being roughly the size of a blue whale, according to fossils.
Crustaceans, such as crabs and lobsters, have proven to be quite persistent throughout history, with several species living since the age of the dinosaurs.
Lobsters are one of the earliest known filter-feeder species, and they predate dinosaurs by hundreds of millions of years.
We also know that current crustaceans are significantly smaller than their progenitors from millennia ago.
The fossilised remains show some truly formidable creatures, and we’re not sure we would have been as tempted to dive during the dinosaurs’ reign.
Horseshoe crabs do not evolve as quickly as other creatures, so their current form is nearly identical to how it was millions of years ago; people do not refer to them as “living fossils” for no reason.
Like sharks, horseshoe crabs have withstood at least four of the planet’s major extinction crises, including the K-T crisis that wiped out most dinosaur species.
Bees have been successfully occupying the planet Earth for a lot longer than you might expect, and they are one of the most significant creatures to do so.
Bees originated during the Cretaceous period (around 60 million years ago), according to research, and were probably zooming from blossom to blossom when T-Rex roamed the wild.
Bumblebees, on the other hand, are known to be susceptible to large-scale extinction events. Scientists believe their populations have been diminished on a regular basis throughout history, but the threat they are currently under due to habitat destruction is unprecedented.
Sea stars (like as well as sea cucumbers and urchins) used to live with sea-dwelling dinosaurs in the days.
From the Early Jurassic to the Early Cretaceous, an extinct genus of sea star Pentasteria swam alongside deep-sea dinos.
It had five arms and a mouth on the center of its underside, similar to a current starfish. Its fossils have been discovered in Europe, so if you’re going to the beach next week, look for them!
Monotreme (egg-laying mammals), a group that dates back 210 million years to the Triassic period, is made up of only two species: the duck-billed platypus and the echidna.
The platypuses have existed throughout the Jurassic period, according to scientists in 2008. When mammals were becoming more common in existence, they coexisted with echidnas (which are still alive today).
It’s not hard to picture duck-billed platypuses coexisting with the dinosaurs.
These weird-looking animals, native to eastern Australia and found only in fossilized remnants dating back millions of years, are a completely distinct species.
We’re not sure how platypus survived the Great Extinction, which wiped out their predecessors, but we are delighted to have them around.
These cuties are truly lovable, yet their numbers are rapidly dwindling, according to the Conservation Index. These cuties are classified as “Near Threatened.”
Lobsters’ ancestors roamed the oceans more than 500 million years ago, predating dinosaurs, and were equipped with six long claws and four eyes.
They belong to the family anomalocaridids, which includes modern crustaceans’ great-great-great-great-grandparents and grandads, and are thought to be the oldest giant filter-feeders ever lived.
Green Sea Turtles
Although it is thought that the first marine turtles emerged during the Jurassic era, sea turtles didn’t start to diversify until 100 million years ago, in the Cretaceous era.
Until 65 million years ago, when dinosaurs became extinct, prehistoric turtles coexisted with them. These turtles were members of the Archelon group of ancient reptiles, which is related to the leatherback sea turtle we see today.
Dinosaurs were once part of the Sphenodontia order of reptiles. The tuatara, the last surviving species of its kind and only found in New Zealand, isn’t a lizard nor a dinosaur: it’s a dragon.
Tuatara arose 200 million years ago in the Upper Triassic epoch, when it split from other reptiles alongside some of the earliest dinosaurs.
Tuatara lizards are the only reptiles and lizards that are more closely related to dinosaurs than others. These lizards, endemic to New Zealand and the last of their kind in the Sphenodontia family, lived alongside dinosaurs.
With dark green skins, spiky backs, and huge, black eyes, Taatara lizards appear to be ancient. These enigmatic chaps have been around for almost 250 million years, and it would be a tragedy if they went extinct now. They are classified as Vulnerable to Extinction.
Cockroaches survived the Permian and Triassic periods, despite the fact that there was no way to exterminate them during the Great Dying!
During the Carboniferous period (roughly 360 million years ago, or 112 million years before the dinosaurs), they were one of the most dominating species, with their current size.