Reptiles by nature, dinosaurs descended from a different group of reptiles known as “dinosauromorphs” about 250 million years ago. The dinosauromorphs were little, lowly creatures with nothing in common with T. brontosaurus or T. rex.
Instead, they resembled house cats in size, moved upright like a greyhound, and had long, slender limbs. Despite not being at the top of the food chain, the dinosauromorphs were successful due to their speed and agility.
What did the earliest dinosaurs look like, and when did they evolve? The oldest known dinosaur was an ecosystem comprised of several diverse species rather than a single animal. There aren’t any earlier dinosaur species that are generally acknowledged.
The Origin of Dinosaurs
Argentina’s Ischigualasto Formation, which dates to the Late Triassic Period and is around 230 million years old, has a variety of animal remains. It demonstrates that early reptiles named rhynchosaurs and creatures with near mammalian ancestry known as cynodonts controlled the ecosystem.
But most importantly, it demonstrates that a variety of early dinosaur species were also present. These include giant animals like the Herrerasaurus as well as smaller bipedal species like Eodromaeus and Eoraptor.
At the Museum, Prof. Paul Barrett has been studying the early development of dinosaurs throughout the Late Triassic and Early Jurassic. Many locations in Argentina and Brazil are contending for the title of the earliest known dinosaur birthplace.
However, they were already recognizable as dinosaurs when they first arrived. This implies that dinosaurs must have had a longer evolutionary history than we now understand. There is some disagreement on how much of that evolutionary history is still lost.
Dinosaurs are a subclass of creatures called archosaurs. Today, crocodiles and birds serve as the group’s representatives (and some include turtles in the group). It formerly comprised all extinct dinosaurs, pterosaurs, and several strange-looking forebears of crocodiles, making it far more diversified.
Many characteristics make up a dinosaur, but its altered hips and legs may be the easiest to understand. For instance, their hips and backbone are significantly more closely connected. They achieve this by transforming portions of their vertebrae into the sacrum, a specifically altered structure that adds these extra connections to their hips.
A reptile’s sacrum can consist of up to two fused vertebrae, but a dinosaur must have at least three. There are up to 12 sacra in modern birds. This characteristic is so remarkable that it was cited in the 1842 definition of Dinosauria.
After learning that the sacrum of two extinct species, the Iguanodon and Megalosaurus, was made up of five fused vertebrae, this was done. These alterations probably occurred due to the early dinosaurs being bipedal or walking on their hind legs.
They have to alter their hind legs as well to achieve it. Early dinosaurs can only be identified by their bipedalism. To become bipedal, dinosaurs had to tuck their legs directly beneath their bodies, unlike crocodiles and lizards, whose legs jutted out at an angle from the torso.
This implies that the connections between the hip and the backbone, the tops of the thigh bones where the bones join the hip, and the joints in the knees and ankles all need modification. All of these characteristics work together to characterize a dinosaur.
Only in the last 20 years have the closest dinosaur relatives been discovered. They are called the silesaurids, medium-sized quadrupedal creatures that reside outside Dinosauria and resemble tall, lanky lizards.
The common ancestor of silesaurids and dinosaurs is 10 to 15 million years older than the first dinosaurs. It is yet unknown what will close this gap. However, it might be the incomplete fossil of the Nyasasaurus Parringtoni, an animal that lived 240 million years ago.
The fossil, which includes several vertebrae and a portion of an arm bone, is mostly ignored because of its shoddy appearance. The fact that some of these bones are from near the hip reveals that three were sacral vertebrae – the three-vertebral sacrum being one of the distinguishing characteristics of dinosaurs – is crucial.
It is uncertain if the fossil was a genuine dinosaur because of its fragmented nature. It is believed to be extremely close to their origins in either case. As it is from the same age as the earliest silesaurs, Nyasasaurus is the only animal that has been provisionally inserted into that gap.
It may be the earliest dinosaur or nearest relative discovered. Nyasasaurus would have been a tiny bipedal predator typical of the early dinosaurs. They were probably busy predators. They likely began life as bipedal creatures with only a few meters of body length, and their hands were capable of grabbing objects.
They weren’t herbivores. Thus, they were probably either omnivores or carnivores. They were rare because even when the earliest dinosaurs became clear-cut, which happened approximately 230 million years ago, they were still uncommon members of the fauna.
Dinosaurs would not have their opportunity until the end-Triassic extinction catastrophe occurred 201 million years ago. Since practically all of the rival archosaurs perished in the mass extinction, the habitat was left empty for the dinosaurs to fill.
The dinosaurs took full advantage of this during the Jurassic and Cretaceous periods, developing into a remarkable variety of animals. Some of the first dinosaurs wandered the Earth a very long time ago.
However, according to experts, it is uncertain where the first dinosaur prints were formed. Much more recently, in Ghost Ranch in New Mexico, hikers came across a few fragments of bone that eventually led to the discovery of a revolutionary dinosaur that reveals how it all began.
The dinosaur, now known as Tawa hallae, had a body around the size of a medium to a big dog, but its bones have helped establish the origins of dinosaurs. The study team utilized the exceptionally complete and well-preserved skeleton remains to place the young dinosaur and other early dinosaurs on the evolutionary tree.
The findings demonstrated that several Triassic dinosaurs from South America were among the most basic creatures yet discovered by paleontologists. They are most similar to the dinosaurs’ common ancestor.
As a result, the first dinosaurs split and evolved into what is now South America more than 220 million years ago, when the continents were together to form one enormous landmass known as Pangea.
The scientists’ analyses point to T. Hallae as a prehistoric theropod that walked on two legs and lived around 213 million years ago. It was predominantly a carnivore. The dinosaur, like Velociraptor, probably had feather-like coverings covering it and claws and serrated teeth for capturing food.
Scientists explored the region in northern New Mexico after the hikers discovered the dinosaur quarry there in 2004. Five to seven fragmentary remains that belonged to T were found. Hallae species were buried among tens of thousands of other fossils in a relatively limited space.
According to the discovered skeletons, this species had a hip height of 4 feet and a snout-to-tail length of almost 9.5 feet. The remains showed that T. was alive. The air sacs surrounding Hallae’s neck and braincase are similar to those in modern birds.
The Mystery Continues
Dinosaurs evolved from previous creatures rather than emerging out of thin air. Theropods, dinosaurs with armor, horns, sauropods, and a few non-dinosaurian aquatic reptiles are all grouped. One of the most prosperous animal species that inhabited the Earth was the dinosaurs.
From tiny creatures only a few feet long to some of the most enormous beasts that have ever walked the Earth, they ruled it for more than 170 million years. However, despite a long evolutionary history, the origin of dinosaurs is still unknown.