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Two New Triassic Dinosaurs From Argentina Reframe Early Dinosaur Evolution

Peer-reviewed finds refine timelines for key trait emergence, with evidence for a late-Carnian turnover linked to climate.

Huayracursor jaguensis. Image credit: Jorge Blanco.
The species lived at the end of the Triassic period, a geological era in which the first dinosaurs and the ancestors of mammals started to appear.
The almost complete skeleton of the small long-necked reptile, named "Huayracursor Jaguensis," has been found in Argentina.
An artist’s reconstruction of Anteavis crurilongus. Image credit: Jorge Blanco.

Overview

  • Anteavis crurilongus, described in Nature Ecology & Evolution, is an early-diverging theropod from the Ischigualasto Formation that falls outside Neotheropoda yet shows features previously thought unique to that group.
  • The Anteavis study documents higher late Carnian diversity in small herbivores and medium-sized predators and identifies a gap in the local dinosaur record beginning at 228.91 ± 0.14 million years ago with recovery in the middle Norian by larger-bodied taxa.
  • Estimated at roughly 1.2 meters in length and about 8–9 kilograms, Anteavis adds to the recognized small- to medium-bodied dinosaur fauna in northwestern Argentina.
  • Huayracursor jaguensis, reported in Nature from the newly recognized Northern Precordillera Basin at Quebrada Santo Domingo, is a nearly complete early sauropodomorph that was larger than typical Carnian counterparts and shows incipient neck elongation.
  • The new basin’s assemblage, including rhynchosaurs, cynodonts, and aetosaurs, broadens the geographic record of Carnian faunas and provides early evidence of synchronous neck elongation and body-mass increase in sauropodomorph evolution.