The theropods are a group of saurischian dinosaurs from the Archosaurs, mostly carnivorous (some species of the Cretaceous were piscivorous, even herbivorous). Its representatives were all bipedal and varied in size. For example, Maniraptors were about 40 cm long (for a weight of 150 g), while Tyrannosaurus rex was up to 12 m long (for a weight of 6 to 7 tons).
They had relatively small upper limbs, meaning that their bodies were supported by the hind limbs, which were used for locomotion. The front limbs were relatively weak but had movable claws. They were probably used to grasp and shred prey.
Originally, when they first appeared during the Triassic period, theropods were small in size. Hunters of insects and other small reptiles, they will continue to evolve during the next 170Ma.
170Ma which constitute, the end of the Triassic and the last two periods of the Mesozoic that are, the Jurassic (50Ma) and the Cretaceous (about 70 Ma). During this time, the theropods evolve in a surprising way.
Some of them will reach considerable sizes, probably to keep pace with the growth of Sauropods, which make up a large part of their prey. Theropods are a very large family of dinosaurs. Some experts talk about 50 or 100 different potential theropod species.
The Theropods belong to the suborder Theropoda, which like the sauropods belong to the Saurischians. They are part of the dinosaurs, which are themselves part of the Archosaurs that survived the Permian / Triassic extinction.
Anatomically, theropods are easily recognizable, they are bipeds with long and muscular lower limbs, either to support the large mass for the largest of them or simply to run quickly, an essential element for all terrestrial predators. As for the upper limbs, they are much smaller, equipped with sharp claws. The whole body ends in a more or less long tail that balances the animal, given its horizontal position.
The respiratory system of theropods is very similar to that of modern birds.
We can also imagine that for the fastest of them, like raptors, like today's cheetahs, the tail can be used as a rudder during the race to be able to turn quickly while maintaining their speed.
About hunting, one of their advantages is that their binocular vision allows them to appreciate distances, which coupled with a good sense of smell makes these animals formidable hunters. Some have discreet and intelligent ways of hunting, others are savage and furry. The way they kill their prey varies according to the hunting method.
The teeth of the theropods, though always curved backward, are not all the same. Some are thick and massive, made to crush, and kill with a single blow of the tooth, which implies an enormous force at the closing of the jaw and therefore very powerful muscles.
Others are more slender and crenelated, made to tear the flesh, and thus cause fatal hemorrhaging.
This technique is one of the most perfect because it requires little effort, just a big blow of the head to plant the teeth and tear.
And it seems, some of them would have had the faculty to kill in a more pernicious way, with a poisoned bite, like the modern-day lizards. Little effort to provide, but a little patience while the prey succumbs to its wounds.
On the internal anatomy side, Theropods are like sauropods, they have hollow bones, whose cavities are used by air sacs which allows them to breathe continuously. Like birds, since birds are theropods, well or at least their direct descendants.
To the question "are all theropods extinct?" some would be tempted to say no, modern birds are their direct descendants, and a lot closer than one might think.
We talk more about it in our article onthe closest things to a modern-day dinosaur.
Appearing during the Upper Triassic, precisely during the Carnian, 230 to 225 million years ago, the theropods then conquered all the continents during the Lower Jurassic. Finally, their population was damaged by the Cretaceous-Tertiary biological crisis (65.5 million years ago), since they all disappeared... except for the lineage of birds (descendants of Maniraptors).
The theropods are divided into several groups, the main ones being the coelophysoids (e.g. Procompsognathus), the ceratosaurs (e.g. Ceratosaurus) and the tetanurids (the majority of carnivorous dinosaurs). Members of the latter taxon, such as allosaurs, T. rex, and dromaeosaurs, had hollow bones and sharp teeth curved backward.
Here is a non-exhaustive list of some of these theropods. As you can imagine, there are far too many of them to list them all, and many of them simply haven't been discovered yet.
The T-Rex, the king of lizards, it is by far the most famous of the dinosaurs, it is one of the last dinosaurs of the large family of Tyrannosaurids which lived at the end of the Cretaceous, it was, therefore, one of the most evolved.
He had a highly developed sense of smell, a big advantage when hunting, or to smell carrion around. For don't be under any illusions, carnivores, of course, but an effortless meal is not to be denied. This is still the case today with large predators.
But contrary to popular belief, although larger than most theropods, it is not the largest of them.
The T-rex does not exceed 12/13 meters for some 6 or 7 tons while some Spinosaurus, reaching 18 meters, exceeds it largely.
So why is it so well known to the general public? Apart from the fact that it has a major role in Jurassic park! It is important to know that for a long time before we were interested in Africa, South America, and Asia in the search for dinosaurs, the most explored place was North America.
It is certainly the USA that has delivered us the most fossils during the 20th century. It must be said that it is immense and in large parts almost virgin, which is not the case of Europe, which over the ages has known a large number of civilizations.
Discovered in 1877, it is one of the first theropods discovered. Smaller and more agile than the T-rex, it is a beast measuring 8 to 12 meters for large specimens. An undisputed predator of this period, Allosaurus was prevalent during the Upper Jurassic in what is now the USA and Europe. It is one of those theropods with fine, serrated teeth.
It was the terror of the stegosaurs and it would be possible that it hunted in packs.
The Spinosaurus is known as what was probably thelargest carnivorous dinosaur ever. its first bones were discovered in North Africa by a German paleontologist at the beginning of the 20th century.
It's a really huge animal, which can reach an impressive size of 18 meters long. It's an interesting dinosaur, this one would be a theropod, but well, an Amphibious one.
It's believed to spend most of its time in the water, much like today's crocodiles. Because of the morphology of its mouth and teeth, scientists imagine it to be piscivorous rather than carnivorous.
The biggest of the theropods from the most dangerous family of carnivores.
Indeed, its long and thin snout, and especially its teeth remind us of the gharial, a piscivorous crocodilian. And what about its bony crest which is not without reminding the dimetrodons and other edaphosaurs, mammalian reptiles of the Permian.
This one had earned its place in ourtop ten of the weirdest dinosaurs. Take a look. The therizinosaurs, as it evolved, took a right-angle turn.
It's a big beast not far from 9 meters for 4/5 meters high weighing no less than 6 tons. By definition it is bipedal, with small upper limbs, but, it has enormous claws, not far from one meter long. And this is the strangest thing, figure it's probably a herbivorous theropod !!!
it's possible that its claws were used to grab plants and slash the trunks. Some paleontologists think it was omnivorous and not herbivorous, several theories clash here. Lastly, its claws were also a beautiful instrument of defense, for example against the terrible Tyrannosaurs. The Therizinosaurus was perfectly capable of defending itself and had a peculiar and disturbing gait, giving the impression that it always sat with its back straight and very straight.
Nature's always full of surprises.
Ceratosaurus lived around the same time as Allosaurus. These two carnivorous dinosaurs resembled each other in many ways, but they were not closely related. Ceratosaurus belongs to a more primitive group of theropods than Allosaurus, which includes Coelophysidae and Abelisauridae. Although it may have weighed up to 2 tons, it was somewhat smaller than Allosaurus and had a characteristic "horn" (actually an expansion of a nasal ridge) on its snout, as well as a row of bony plates along its back. Ceratosaurus also differed from Allosaurus by having the fourth finger with a claw on the forelimbs instead of the three fingers typical of most theropods.
Deinonychus is a member of the Dromaeosauridae family. Like all theropod dinosaurs, it was bipedal, moving on its hind legs. Its main offensive weapon was a sickle-shaped claw, up to 13 centimeters long, carried by the second finger of each hind limb. The tail was slender and stiff, stiffened by bundles of bony rods. These extensions of the caudal vertebrae helped the animal maintain its balance when running or attacking prey.
Deinonychus served as a model for the "raptors", the aggressive little dinosaurs in the movie Jurassic Park (1993). The term "raptor", which is too often used to refer to Dromaeosaurids in general, is actually a contraction of Velociraptor, a much smaller genus of Dromaeosauridae than Deinonychus. It should be avoided because it has no scientific validity when applied to these dinosaurs. Deinonychus grew to 2.50 meters in length or more and must have weighed about 50 kilograms. It was clearly a fast and agile predator, its developed brain allowing it to perform relatively complex actions during the capture of its prey.
Dromaeosaurids and Troodontidae are the closest known relatives of Archaeopteryx and birds in general. They have many characteristics in common with birds, including remarkably elongated arms and hands and a wrist capable of lateral flexion. These adaptations appear to have helped these dinosaurs grasp their prey and then allowed the birds to make the wing movements necessary for flight.
Megalosaurus is a carnivorous dinosaur that was the first dinosaur to be scientifically described. Found in fossil form in the Middle Jurassic (about 165 million years ago) in England, it was described by William Buckland in 1824 on the basis of dissociated bones that included vertebrae, parts of the pelvis and hind limb, and a fragment of the mandible with sharp teeth.
Megalosaurus was originally reconstructed as a large four-legged lizard before it was realized that it was actually a theropod, a carnivorous bipedal dinosaur with short forelimbs and clawed fingers. Its jaws had long, blade-like teeth, very similar to those of Allosaurus and other large theropods to which it was certainly related. Almost two centuries after its discovery, Megalosaurus remains a rather poorly known dinosaur. Fossils belonging to a perhaps related genus, Poikilopleuron, found in the 19th century in Normandy, near Caen, were destroyed during the Second World War. Since then, this region has yielded new remains of Middle Jurassic theropods.
Oviraptor is a small theropod dinosaur, carnivorous or omnivorous, which lays its eggs like a bird. It was found in fossil form in the Upper Cretaceous (about 80 million years ago) in Central Asia.
Oviraptor was about 1.80 m long and moved in a bipedal position with long, well-developed hind legs. Its front limbs were elongated and slender. They had three long clawed fingers at the end and were capable of grasping and tearing food. Its head was short, with very large eyes surrounded by a ring of bony plates; it is possible that this dinosaur had a stereoscopic vision. Its skull was surmounted by strange ossified ridges and its jaws were toothless but probably covered with a horny beak-shaped case.
The name Oviraptor comes from the Latin words for "egg" and "thief", as it was originally discovered in association with eggs thought to belong to Protoceratops, a primitive Ceratopsian dinosaur. It was then assumed that it was feeding on these eggs. However, studies on the microstructure of the shells showed that they were laid by a theropod and not by a ceratopsian. Since the early 1990s, several skeletons of Oviraptor have been found squatting on eggshells, in a position exactly like that of a hatching bird.
The velociraptor is surely one of the most famous dinosaurs of all time, together with the t-rex they form the most famous pair of dinosaurs for the general public, mainly thanks to its presence and its major role in numerous works of fiction such as the Jurassic Park saga.
The velociraptor is a carnivore of the theropods family whose name means "agile thief", it lived in Asia, in what is now Mongolia and China about 80 Ma ago during the Mesozoic period called Cretaceous. He was relatively small since he was about 1.20 tall and 1.80 long and weighed about 15kg. It was probably covered with feathers and could move at a speed of about 40km/h.
The Baryonyx whose name means "powerful claw" is a carnivorous theropod, certainly a little less known than some of its cousins, but just as impressive. It lived in Europe about 120 million years ago, fossilized bones have been found in Spain and England. it was quite a respectable size as it was about 12m long for 2 tons. Some of its fossilized claws measured up to 30cm long!
It was better not to annoy it, it was feared by all the herbivores in its neighborhood.
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