At a time of immense proliferation of species, dinosaurs were only a modest addition to the biosphere, and there was nothing to suggest that they would become the lords of the planet. Around the end of the Triassic period, around 230 million years ago, in a region that much later would be called by certain mammals of South America, the first dinosaurs appeared.
A literal translation of the name, derived from Greek and Latin, would be something like “terrible lizards” – more than appropriate for creatures like the most famous of all dinosaurs, the fearsome tyrannosaurus rex. The origins of this fascinating lineage, however, did not inspire such confidence.
Take, for example, the eoraptor, which lived 231.4 million years ago in Argentina. From the tip of tail to head, 1 meter long. Standing upright, this bipedal creature measured no more than 50 cm. This is an excellent example of the main characteristic that marked the origin of dinosaurs: they started small, modest. From the same period is the Herrerasaurus, another Argentine dinosaur. In length, it could even impress, with an imposing 3 m. At the height, not much more than 1.8 m. The relatively small size is explained by the great competition for space that marked that time.
In addition to dinosaurs, several other creatures sought their place in the sun. Among them, many amphibians, crocodilians, cynodonts (reptiles halfway to becoming mammals) and, running around, the first real mammals, which also appeared there. A remarkable – and random – event would decide this fierce dispute for dominance.
Known since the 19th century, it has already caused a lot of confusion. Its skeleton is difficult to interpret, and there were even those who suggested it was a quadruped, or that it jumped like a kangaroo. Modern biomechanical analysis shows that it could only be bipedal. Plateosaurus reached up to 8 meters in length and could weigh up to 4 tons. And, that’s all by eating leaves.
Everything seems to point to the fact that the first dinosaurs must have walked on two legs. And they quickly evolved to divide into two groups, one with a pelvis (the famous pelvis) that most resembled that of birds (the ornithischians) and another that had this bone constitution closer to the lizard style (the saurischians).
Interestingly, modern birds are descendants of this second group, showing how natural selection produces twists and turns, playing haphazardly with the characteristics of living beings. It was precisely one of these comings and goings that caused some of the most famous dinosaurs of later times to revert to a quadrupedal posture.
With a modest skull and a light, bipedal build, Herrerasaurus had a movable neck and adequate dentition to give deadly bites to its victims. Fossilized faeces indicate that they probably did not eat plants.
Eoraptor was widely regarded as the oldest known dinosaur until recent discoveries proved otherwise. Since the discovery of the first Eoraptor fossils in 1991, several well-preserved specimens have been uncovered. The fact that Eoraptor was one of the first dinosaurs makes it tough to categorize. It lacks the specialized properties of later dinosaurs’ main groups and shares characteristics with various other groups.
Being versatile, this creature was probably omnivorous, as indicated by the two types of teeth it had. Those in the upper jaw were serrated like a predator’s, and those in the lower jaw seemed better for plant consumption.
Eodromaeus was discovered in 1996 but did not receive a name or description until 2011. It was once thought to be a new species of Eoraptor, another early dinosaur. However, a later study indicated that Eodromaeus was a brand-new dinosaur. Some scientists believe Eodromaeus is related to the yet-to-be-discovered “Eve,” or mother of dinosaurs.
Eodromaeus was a tiny fish, measuring approximately 1.2 m (3.9 feet) in length from nose to tail and weighing about 5 kg (11 lb). It was a carnivore and one of the first members of the theropod dinosaur family – one of the earliest known groups of carnivores that led to the T. Rex.
Sanjuansaurus was an early Herrasaurid dinosaur related to Herrerasaurus ischigualastensis. It was discovered in 1994 in the Ischigualasto Formation of San Juan, Argentina. Sanjuansaurus was named after the location where it was discovered in 2010 by Oscar Alcober and Ricardo Martinez.
Sanjuansaurus was roughly the same size as a medium Herrerasaurus, measuring about 6 meters (20 feet) long overall and weighing 350 kilograms. Apart from being closely related to Herrerasaurus, the Sanjuansaurus’ hip bones and tibia resemble those of Staurikosaurus.
Panphagia was discovered in the Ischigualasto Formation of Argentina’s Ischigualasto Provincial Park in 2006 by Argentinean paleontologist Ricardo N. Martinez. In this area, several other dinosaurs have been found. Panphagia is a primitive sauropodomorph that looks a lot like Saturnalia, another early sauropodomorph.
Only one Panphagia specimen has been discovered so far, consisting of an incomplete skull, vertebrae, pectoral girdle, pelvic girdle, and hindlimb bones. Panphagia’s teeth indicate that it was maybe an omnivore, although no one knows for sure. Panphagia is derived from the Greek words “pan” which means “all” and “phagein” which means “to eat/eater.”
Nyasasaurus parringtoni is currently the world’s oldest dinosaur. Nyasasaurus is either the earliest known dinosaur or the closest relative to the first real dinosaurs, according to scientists. Nyasasaurus’ upper arm and backbones were discovered in Tanzania in the 1930s, but the fossils were not researched thoroughly until recently. In 2012, scientists estimated that Nyasasaurus existed around 240 million years ago, nearly 10 to 15 million years older than the previously considered oldest dinosaur.
Due to limited fossils collections, there is very little known about Nyasasaurus. Its length, including its tail, is estimated to be between 6.5 and 10 feet (2 to 3 meters) based on the fossils. However, because no skull bones have yet been discovered, it is unknown what the animal ate or if it walked on two or four legs. But Nyasasaurus did have a bony crest on its upper arm bone called a deltopectoral crest, indicating that it was a dinosaur (all dinosaurs have this crest).
This article sums up some of the first dinosaurs present on earth. Cataclysmic events caused them to be eradicated and wiped off completely from the face of the planet. To be exact, about 66 million years ago, at a time when there was worldwide environmental change. Geological evidence suggests that they became extinct from vast volcanic eruptions and/or the impact of a large celestial object on the Earth. Had it not taken place, dinosaurs would very well still be alive today. Imagine that! Leave your comments below.