Huayracursor

MEANING: Wind runner

PERIOD: Late Triassic

CONTINENT: South America

Huayracursor is an early sauropodomorph that lived during the Late Triassic period in what is now Argentina.

Abstract from paper: During the Late Triassic epoch (237–201 million years ago), the terrestrial ecosystems of Pangaea underwent drastic changes1,2 that led to the rise and diversification of mammaliaforms3, crocodylomorphs4 and dinosaurs5. Although the Carnian sedimentary rocks of South America provided much of the available evidence for understanding the early evolution of these clades, key discoveries have remained restricted to the Ischigualasto-Villa Unión6,7 and Paraná basins8 in Argentina and Brazil, respectively. Here we report a Carnian tetrapod assemblage from the previously unrecognized Northern Precordillera Basin in northwestern Argentina. Discoveries at this basin, in the Quebrada Santo Domingo site, include a nearly complete skeleton of the early sauropodomorph Huayracursor jaguensis gen. et sp. nov., and typical components of Late Carnian faunas, such as hyperodapedontine rhynchosaurs, gomphodontosuchine traversodontid cynodonts, and aetosaurs. Compared to its generally small and short-necked Carnian counterparts9,10, Huayracursor is larger and exhibits an incipient elongation of its cervical vertebrae, representing an intermediate condition for size and cervical elongation between known Carnian and Norian sauropodomorphs11. This discovery provides one of the oldest pieces of evidence of increased body mass and neck elongation in early Sauropodomorpha.

Huayracursor is from the Late Triassic. The Triassic is the first geologic period of the Mesozoic, spanning from the end of the Permian Period 252 million years ago to the beginning of the Jurassic 201 million years ago. Both the start and end of the Triassic were marked by major extinction events. In the aftermath of the devastating Permian-Triassic extinction, life gradually rebounded, giving rise to new groups that would shape the Mesozoic Era. The global climate during the Triassic was mostly hot and dry, with vast deserts dominating the interior of the supercontinent Pangea. Over time, as Pangea began to rift apart, the climate slowly became more humid, creating new environments and opportunities for ecological diversification.

For much of the Triassic, dinosaurs were not yet the dominant terrestrial animals. Instead, the land was populated by a variety of other reptiles, including sprawling archosaurs. Early synapsids, the lineage that would eventually lead to mammals, were also still present but declining. Vegetation was dominated by drought-tolerant plants such as seed ferns, cycads, ginkgoes, and early conifers. These hardy plants formed the base of recovering ecosystems during this volatile time.

It wasn't until the Late Triassic, around 230 million years ago, that the first true dinosaurs appeared. Early forms were small, bipedal, and lightly built, likely preying on insects and small vertebrates. While they remained minor players compared to other reptilian groups, their agility, upright stance, and efficient breathing gave them advantages that would prove crucial in the long run. As the Triassic drew to a close, another mass extinction event reshaped life on Earth once again, wiping out many of the dominant reptile groups and clearing the way for dinosaurs to rise to prominence in the Jurassic.

Huayracursor is a basal sauropodomorph. Sauropodomorpha is the larger group that contains the long-necked sauropod dinosaurs. Basal sauropodomorphs, often informally referred to as "prosauropods," were early members of the lineage that eventually gave rise to the massive quadrupedal herbivores. These early sauropodomorphs thrived during the Late Triassic and Early Jurassic periods and represent some of the first large-bodied plant-eaters to evolve within Dinosauria. They were generally medium-sized, with long necks, small heads, and leaf-shaped teeth suited for a herbivorous or omnivorous diet.

Unlike their gigantic descendants, most basal sauropodomorphs were primarily bipedal, though some likely used all four limbs when moving slowly or feeding. Their forelimbs were shorter than their hindlimbs, and many had grasping hands with large claws - features that suggest a degree of versatility in both locomotion and feeding behavior. Fossil evidence of these dinosaurs has been found across much of Pangea, showing they were among the earliest dinosaur groups to achieve a widespread distribution. Though often overshadowed by the sauropods they gave rise to, these early forms played a crucial role in the rise of large-bodied herbivores and the overall success of dinosaurs in the Mesozoic.