The new species is one of the oldest dinosaurs, having lived approximately 230 million years ago, during a period of boom in terrestrial ecosystems characterized by the emergence of new animal groups. Given its significance, the discovery has been published in the prestigious journal Nature.
A paleontological team has discovered in the Precordillera of La Rioja, at more than 3000 meters above sea level, the almost complete and practically articulated skeleton of a long-necked dinosaur that inhabited the region about 230 million years ago, being one of the oldest dinosaurs.
This antiquity places the new species, named Huayracursor jaguensis, in the Late Triassic, a period of great transformations in terrestrial ecosystems marked by the emergence of the first oldest dinosaurs and the ancestors of mammals.
The discovery took place in the Quebrada de Santo Domingo, a region of great fossil richness where, over the last ten years, not only other oldest dinosaurs have been found, but also various representatives of the Triassic fauna, such as rhynchosaurs and traversodontid cynodonts. Due to its importance, the discovery of this new species was published in the prestigious journal Nature.
“It is one of those oldest dinosaur discoveries that do not happen often. The region where we work is very inhospitable due to the altitude, strong winds, low temperature, and changing climate, although it captivates with its spectacular landscapes,” explains Martín Hechenleitner, a researcher at the CONICET at the Regional Center for Scientific Research and Technological Transfer of La Rioja (CRILAR) and first author of the article.
“The name Huayracursor honors the wind, while jaguensis reflects the proximity to Jagüé, an ancient herders’ village located 40 kilometers from the Quebrada Santo Domingo.”
The team responsible for the discovery of Huayracursor also participated in the first expeditions to this area in the west of the province of La Rioja, which until then remained practically unexplored and where the first Triassic fossils began to be revealed.
“We estimate that Huayracursor must be between 230 to 225 million years old, making it one of the oldest dinosaurs in the world.
For more than half a century, the faunas of that age were confined to discoveries in the Ischigualasto Provincial Park (San Juan), in the region of Cerro Las Lajas (south of La Rioja), and in the state of Rio Grande do Sul (Brazil),” notes Agustín Martinelli, a researcher at the CONICET at the Argentine Museum of Natural Sciences “Bernardino Rivadavia” (MACN) and second author of the article.
“This new region, within a geological basin practically unexplored, opens a perspective of great discoveries.
Rarely in life can one say that completely novel sites have been found, with an extraordinary fauna for its preservation and abundance.”
Characteristics and phylogenetic position of Huayracursor, one of the oldest dinosaurs
Huayracursor is a primitive sauropodomorph, a very successful lineage of herbivorous dinosaurs that includes the long-necked giants like Argentinosaurus and Patagotitan. Phylogenetic analyses group it within the clade Bagualasauria, along with relatives that lived at the same time in what is now the State of Rio Grande do Sul, in Brazil.
“Huayracursor is novel because it presents two key traits: a neck considerably longer and a larger size than most of its contemporaries. These aspects confirm a very early appearance and synchronous emergence of both characteristics, which were fundamental in the evolutionary history of sauropodomorphs,” indicates Hechenleitner.
From the skeleton of Huayracursor, a part of the skull, a complete vertebral series up to the tail, and the practically complete fore and hind limbs were recovered. Due to the almost complete state of the fossil, Hechenleitner believes it will become a reference for studying the early evolution of sauropodomorphs and dinosaurs in general.
Regarding the size and weight of the animal, Malena Juarez, a doctoral fellow at CONICET at CRILAR and one of the authors of the article, notes: “We estimate a length of approximately two meters and about eighteen kilograms for an adult individual, being almost double that of other close relatives found in Argentina, such as, for example, Eoraptor lunensis, the famous primitive dinosaur found in the Ischigualasto Provincial Park, in San Juan.”
Currently, Juarez is working on the detailed description of the remains of Huayracursor as part of her doctoral thesis, in order to thoroughly understand its anatomy and its relationships with other dinosaurs from South America, Africa, and India.
Regarding the team’s future expectations, Sebastián Rocher, a researcher at CONICET at the National University of La Rioja (UNLaR) and another of the authors, indicates: “From stratigraphic and sedimentological studies, we were able to recognize that the Triassic terrains of the Northern Precordillera belong to a sedimentary basin that evolved independently from other basins of southwestern Gondwana. This opens the possibility of extending the explorations even further west, in the Andes mountain range.”
The study also involved researchers from CONICET Lucas Fiorelli (CRILAR), Jeremías Taborda (CICTERRA, CONICET-UNC), and Julia Desojo (National University of La Plata).
