Daftarsbmptn.com – The oldest known dinosaur was discovered more than a decade ago in Tanzania. It was the Nyasasaurus, an ancient species estimated to have lived around 243 million years ago.
They lived in the mid-Triassic period, long before giant dinosaurs like Tyrannosaurus rex or Brachiosaurus emerged and dominated the Earth. They were relatively small, standing around 90 centimeters tall and weighing between 22.5 and 60 kilograms.
However, the appearance of dinosaurs was not sudden. The evolution towards their era was a long process, occurring slowly over millions of years, eventually reaching a period known as the Age of Dinosaurs, when various species, both large and small, ruled the planet.
At the time of the early dinosaurs’ emergence, all of Earth’s landmasses were still united in a single supercontinent called Pangea. From this giant landmass, various groups of ancient creatures spread.
Three regions in the Northern Hemisphere Wyoming, Morocco, and Nova Scotia have become crucial locations for scientists reconstructing ancient ecosystems and the evolutionary process of dinosaurs.
According to David Lovelace, a vertebrate paleontologist at the University of Wisconsin Geology Museum, conditions on Earth at that time were completely different from what they are today.
“Morocco would have been pushed up against the eastern coast, and as it separated, so would the dinosaurs,” Lovelace said, as quoted by Discover Magazine, describing how the changing shape of the continents influenced the distribution of these ancient creatures.
He explained that at that time, the climate initially tended to be humid. However, shortly thereafter, during an event known as the Carnian Pluvial Episode (CPE), massive volcanic activity off the coast of North America caused extreme climate change and heavy rainfall for over a million years.
Before the CPE, much of the land was desert, making travel across the continent much more difficult.
“The land at the beginning of the Triassic was relatively flat with a few mounds where the Rocky Mountains are now,” Lovelace said.
The mounds were likely highlands covered with pines, ferns, and cycads. Pollen, spores, and fossilized leaves later discovered reveal what kind of vegetation flourished at the time.
Early dinosaurs coexisted with the giant amphibian Temnospondylis, which could grow up to 3 meters long and swim in both freshwater and coastal environments.
Also present were archosaurs, a large group that gave rise to the lineages of birds, crocodiles, and dinosaurs, with more than 700 non-avian dinosaur species belonging to this group.
Most of the earliest dinosaur fossils, dating from about 230 million years ago, are found in the Southern Hemisphere. However, a recent discovery in Wyoming suggests that at least one dinosaur from the same period lived in the north, a species named Ahvaytum bahndooiveche.
“It was about the size of a chicken with a long tail and neck,” Lovelace said. “It looked like a small, meat-eating dinosaur and it was.”
However, the descendants of this line would eventually evolve into long-necked sauropods that walked on four legs, ate vast amounts of plants, and grew as large as skyscrapers.
Early dinosaurs were initially carnivores or at least omnivores, surviving by preying on or consuming whatever was available.
It was only later, in the course of evolution, that their lineage split into two major branches: sauropods and theropods, which evolved into giant herbivores and predatory carnivores that dominated the land, respectively.
Why are most early dinosaur fossils found in the Southern Hemisphere? The answer has to do with geology. “Most of the Late Triassic rocks in North America are confined to slightly younger sections,” explains Lovelace.
This means scientists have struggled to find rock layers old enough to preserve the earliest fossils in the region. A similar situation has occurred in Europe, though for different reasons.
On that continent, older rock layers tend to be underwater, making them difficult to access for research. Nevertheless, Lovelace believes there are still many early dinosaur fossils waiting to be discovered.
“It’s likely that as more specimens are discovered, the rocks will be even older and come from different parts of the world,” he said.
The discovery of Nyasasaurus and its ancient relatives not only expands our understanding of dinosaur origins but also provides a glimpse into how life on Earth gradually shifted toward the era of giant dominance.