Early Experiment at the Dawn of Dinosaur Evolution Discovered

Strategic Insights -

Argentinian researchers have made a groundbreaking discovery in northwestern Argentina, revealing a Carnian theropod with features previously thought to belong only to much later neotheropods. This finding indicates greater early dinosaur diversity than expected, as well as a possible climate-related ebb and return of dinosaur abundance. The study, published in Nature Ecology & Evolution, provides new insights into the early dinosaur diversification event that followed the Carnian pluvial episode.

Key Takeaways:

  • The newly discovered theropod, Anteavis crurilongus, has features that were previously thought to belong only to much later neotheropods, indicating greater early dinosaur diversity than expected.
  • The study suggests that early dinosaur diversification in southwestern Pangaea was considerable at onset, probably punctuated by climate-driven turnover before later dominance.
  • Anteavis crurilongus adds a well-supported data point near the base of Theropoda and expands the anatomical spectrum present during the Carnian.
  • The fossil assemblages in northwestern Argentina offer a way to examine abundance, body size structure, and faunal shifts during the dinosaur diversification event that followed the Carnian pluvial episode.
  • The studied area shows a shift to semi-arid conditions coincident with diverse small dinosaurs in the Cancha de Bochas Member, followed by a return to more humid conditions and an ensuing record gap in dinosaur occurrences beginning around 228.91 Ma.
  • Records rebound about 15 Myr later in the middle Norian with larger-bodied dinosaurs and renewed abundance and diversity.

Statistics:

  • The new theropod, Anteavis crurilongus, has a femur at 80% of tibial length and metatarsal III at 63% of tibial length.
  • The study dates the Cancha de Bochas Member back to approximately 231 million years ago.
  • A shift to semi-arid conditions is observed in the Cancha de Bochas Member, followed by a return to more humid conditions and an ensuing record gap in dinosaur occurrences beginning around 228.91 Ma.
  • The area shows a 15 million-year gap in dinosaur records before rebounding in the middle Norian.

Sources:

  • Martínez et al., A Carnian theropod with unexpectedly derived features during the first dinosaur radiation, Nature Ecology & Evolution (2025). DOI: 10.1038/s41559-025-02868-4
  • Early experiment at the dawn of dinosaur evolution discovered (2025, October 24) retrieved from https://phys.org/news/2025-10-early-dawn-dinosaur-evolution.html