Researchers have always maintained that Triassic dinosaurs were small, chicken-sized critters and that it was not until the Jurassic period — about 180-million years ago — that massive herbivorous sauropods, like the Diplodocus and Brachiosaurus, emerged. However, the discovery of a new dinosaur species in Argentina suggests that the animals achieved gigantism during the late Triassic period, about 30 million years earlier than previously believed.
Dr. Cecilia Apaldetti, a paleontologist at Argentina’s Universidad Nacional de San Juan, and her team unearthed the dinosaur’s fossils at the Balde de Leyes site in the San Juan Province in 2015. The remains were transported to the lab where they were carefully cleaned and examined. After comparing the fossils to those from other dinosaur species, the scientists concluded that the ancient animal was an early sauropodomorph, part of the species that later evolved into the gigantic sauropods.
The researchers estimate that Ingentia prima — Latin for “first giant”— weighed close to ten tons, or as much as two to three elephants, and measured about 33 feet long. Apaldetti believes Ingentia was not just the largest dinosaur, but also the biggest land animal on Earth during the Triassic period. She asserts, "It is a true giant, especially for that moment of evolution where most of the animals that coexisted did not exceed two meters in height and the largest reached, at most, three tons.”
Though big for its time, Ingentia was a midget compared to the Patagotitan, a 69-ton behemoth that roamed Earth during the Cretaceous period. Also, unlike the later sauropods who had tall, pillar-like straight legs, Ingentia’s legs were flexible and bent. It also had a much shorter neck than the Jurassic-period giants, which boasted among the longest necks relative to body length of any animals ever.
A close examination of the rings on Ingentia’s bones suggests that the animal grew in short, quick bursts that occurred seasonally. This is different from the later sauropods that developed at a consistent rate until they reached adulthood. "It is a new way to get body size in an early moment in evolutionary history," said Apaldetti. "This strategy was not used again in the history of dinosaurs."
The ancient sauropod’s impressive size was probably due to its bird-like respiratory system. Similar to the one found in later dinosaurs, it comprised both lungs and air sacs, giving the animal large reserves of oxygenated air and keeping it cool despite its massive size. Though Ingentia is the only known gigantic Triassic-period dinosaur, Apaldetti, who published her findings in the journal Nature Ecology & Evolution on July 10, 2018, believes there are bigger and even stranger dinosaurs just waiting to be unearthed!