According to fossils, researchers believe that the earliest dinosaurs evolved about 230 million years ago in the late Triassic era. However, before the dawn of the “Terrible Lizards” there were other vicious creatures that lived in the Earth’s oceans and roamed the land.
One thing you may notice about the Cynognathus is that it has hair, which is a trait that most mammals have. Well, that’s because Cynognathus is a part of an order called Therapsids, which were distant relatives of mammals.
The Cynognathus lived 251 million to 245.9 million years ago, and the first mammals appeared around 200 million years ago. These creatures, which died out just as the earliest dinosaurs evolved, were found in modern day Africa and South America.
They were about the size of a modern wolf, and had long, powerful jaws that were used to hold their prey down. It would then use its dog-like teeth, which included sharp incisors and canines, to kill and devour their food, which were small herbivores. They were pack-hunting animals that were also incredibly fast runners. Their short limbs were tucked under their body, allowing for rapid movement.
If you don’t like bugs, you should be happy that you’ll never came across an Arthropleura, which is the largest land living “bug” to ever crawl upon the earth. It would grow to be a foot and half wide and more than six feet long.
They lived in the swamplands around the equator in what is present-day North America and Europe about 320 to 290 million years ago. They died around the time that the oxygen levels in the atmosphere decreased, but it is unclear if the oxygen levels played a role in their extinction or if another factor was responsible.
The Estemmenosuchus may look like a mix between a rhino, a hippo, and Triceratops, but it was neither a mammal nor a dinosaur. Instead, it was a Synapsida, which is an ancestor of mammals. The Estemmenosuchus lived 267 million years ago in modern day Russia.
Researchers are unsure if the animal, which was up to 15-feet long and weighed nearly 1,000 pounds, was a herbivore, carnivore, or omnivore. It had sharp teeth, suggesting that it was capable of eating flesh. However, it had a big body, which was good at digesting food. It also had short legs and its mouth easily reached the ground, meaning it had an ideal body for grazing.
The Estemmenosuchus was one of the animals that went extinct during the “Great Dying” that happened about 252 million years ago.
The Helicoprion first appeared about 270 million years ago, some 40 million years before the dinosaurs appeared. It’s important to note that while the Helicoprion looks a lot like a shark, it was not a species of shark. It was more closely related to chimaeras and ratfish. They went extinct about 20 million years before the earliest dinosaurs evolved.
The most notable aspect of the Helicoprion was its spiral set of teeth called a “whorl,” and it was first discovered over a century ago. The problem was that the Helicoprion was mostly made of cartridge, which isn’t ideal for creating fossils. So besides the whorls, there isn’t much in terms of Helicoprion remains.
For a long time, researchers were unsure where the whorls were on the body, but the main theory is that it was found on the bottom jaw and worked in a way that was similar to a buzz saw. When it would bite on to something, the teeth, which were permanent, would spin backward, cutting through its prey like a serrated steak knife.
Besides having a terrifying bite, Helicoprions were also quite large, often about 30 to 40 feet long.
About 20 million years before the dinosaurs first evolved around 230 million years ago, the first species of Nothosaurus (“false lizard”) evolved. They diversified, and there were at least 13 subspecies altogether. They all had long, flexible necks and big, broad heads, and their mouth was full of needle-like teeth.
Nothosauruses, which were about 13 feet long, were also notable because they were both a land and aquatic animal, similar to a seal. Their bodies, with webbed toes and robust limbs, made them excellent swimmers, but they didn’t usually chase after their prey on land or in the water. Instead, they would lie in wait and then surprised their prey, which consisted of fish and marine life.
5. Inostrancevia alexandri
The Inostrancevia alexandri was the largest member of Gorgonopsidae, which was a mammal-like reptile that was part of the Therapsida class. They were about 12 feet long, and their head alone was two feet big. Their size would have made them one of, if not the top predator when they lived, which was about from 299 to 252 million years ago in modern day northern Russia.
The Inostrancevia had two six-inch long canine teeth, which they used to rip the chunks of flesh off their prey, and then they were able to swallow it whole. Not even armored animals were safe; their canines would have been so strong they would be able to cut through it, and then using their powerful neck, they’d simply tear out of the meat.
4. Thalattoarchon Saurophagis
Thalattoarchon saurophagis, which means “lizard-eating sovereign of the sea,” got its catchy name because it ate prey that was as big as itself. No small feat, considering the Thalattoarchon was the size of a bus.
The 28-foot ichthyosaur first appeared about eight million years after the Earth’s biggest mass extinction, the Permian extinction. That was roughly 252 million years ago, and left about 95 percent of all life extinct.
The Thalattoarchon is the oldest known apex predator and it showed that marine life had fully recovered after the greatest mass extinction in Earth’s history. The Thalattoarchon killed its prey by using its sharp, four-inch conical teeth that it used to grab onto slippery fish and squid.
For unknown reasons, the Thalattoarchon and all other types of ichthyosaurs went extinct about 90 million years ago, about 25 million years before the dinosaurs bit the dust.
There is a common misconception that Dimetrodons were dinosaurs. While they do look like them, and they are often used in dinosaur toy collections, they weren’t even reptiles. They were Synapsidas, and were actually more like mammals than reptiles. Also, they didn’t even live at the same time as dinosaurs. They went extinct 40 to 50 million years before the first dinosaurs evolved.
When they were alive, which was from 295 to about 272 million years ago, Dimetrodons were apex predators. They were the first known land carnivore to use serrated teeth to eat other animals like reptiles and amphibians. They were about 5.5 to 15 feet long, and probably their most notable feature was their spiny back fin. While there is some debate as to what it did, the most prominent theory is that it was used to attract mates and a way for the cold blooded animals to collect heat.
No, this isn’t a nickname Shaquille O’Neal gave himself. Instead, 400 million years ago the Dunkleosteus was the king of the ocean was. The armored fish was bigger than a modern day killer whale. They grew to 33 feet long and could weigh four tons. Besides being huge, Dunkleosteus also had an incredibly intense bite that was calculated to be 1,100 pounds of force. That would mean that their bite was as powerful as a Tyrannosaurus Rex, or modern alligators. This was powerful enough to bite through a shark, which was what Dunkleosteus preyed on. That’s right: they were so big and fearsome that they ate sharks, meaning humans wouldn’t have stood a chance if they came across one.
Luckily, no humans ever saw a living Dunkleosteus. They died out about 375 to 360 million years ago, during one the five major mass extinctions, the Late Devonian extinction. During the extinction, between 79% and 87% of all ocean species died out.
1. Carnufex Carolinensis
While there isn’t a whole lot known about Carnufex carolinensis, because only two Carnufex fossils have been found, what researchers do know about them is that they were nine-foot members of the Crocodylomorpha family, which is part of the lineage of modern crocodiles. They were probably the dominant predator when they lived 231 million in what is today North Carolina. They evolved just before the dinosaurs, and may have been the top predator before the rise of the dinosaurs.
Unlike other members of the Crocodylomorpha superorder, Carnufex walked on two feet. So, yes, picture a giant crocodile running after you on two feet, and your pants should soon be sufficiently wet. It had blade-like teeth, which is how it got its name, Carnufex, which means “butcher.” It feasted on armored reptiles and early mammals. They ultimately died out during the Triassic–Jurassic extinction event, which happened about 201 million years ago.