Scientists have uncovered the oldest long-necked dinosaur fossil ever discovered, shedding new light on the evolution of these prehistoric giants. High in the Andes, researchers braved rugged terrain and unpredictable weather to find clues about the geological history of an ancient basin. Their perseverance paid off when they stumbled upon a nearly complete fossilized skeleton of a new sauropodomorph species, part of the long-necked, plant-eating group. This discovery, named Huayracursor jaguensis, offers a unique glimpse into the past, revealing that these dinosaurs lived around 230 million years ago during the Late Triassic period. The 1.5-meter (5-foot) tall dinosaur's longer neck and larger size compared to its contemporaries suggest that two evolutionary changes were happening simultaneously: longer necks and larger bodies. This finding challenges previous beliefs about the evolution of early sauropodomorphs, which were once thought to be small and short-necked. The fossil was found in Argentina's Quebrada de Santo Domingo, a region that has yielded significant dinosaur discoveries in the past decade, including other Triassic reptiles and mammal ancestors. The study of Huayracursor jaguensis provides valuable insights into the ecosystem changes that occurred during the Late Triassic and the evolution of early sauropodomorphs. The research team's initial goal was to understand the relationship between the Quebrada de Santo Domingo and nearby geological systems, particularly the well-studied Ischigualasto–Villa Unión Basin. This discovery opens up new possibilities for major findings in the virtually unexplored geological basin, as it is rare to find such well-preserved and abundant fauna in new sites. The fossil's location in a rock layer below a dated volcanic layer further supports its age, placing it in the earlier Carnian stage of the Late Triassic. The Huayracursor fossil, found at an altitude of 3,000 meters (9,842 feet) in the Andes, is one of only two known Carnian-age sauropodomorphs with a well-preserved hand. By assembling the fossil fragments, scientists determined that Huayracursor was nearly 5 feet tall and weighed around 40 pounds, nearly double the weight of its closest relatives. The longer fourth and fifth vertebrae indicate early signs of neck elongation, and the length-to-width ratios of the neck bones support this evolutionary trend. This discovery highlights the ongoing neck elongation and body bulking that characterized the sauropodomorph evolutionary story. The study's findings have significant implications for understanding the dinosaur evolution timeline and the relationship between the Triassic terrains of the Northern Precordillera and other basins in southwestern Gondwana. The team believes that further exploration in the Andes Mountains could reveal new clues about the adaptation and evolution of ancient animals during the Late Triassic.
