Bird-like fossil footprints from the Late Triassic

Area of Science:

• Paleontology
• Vertebrate Paleontology
• Ichnology

Background:

• The fossil record of birds begins in the Late Jurassic with Archaeopteryx.
• Avian ancestors (coelurosaurs) date back to the Early Jurassic.
• Late Triassic theropods lack skeletal evidence of avian features like a reversed hallux.

Purpose of the Study:

• To describe novel fossil footprints with avian characteristics.
• To investigate the origin and evolution of birds through ichnology.
• To challenge existing timelines for avian evolution.

Main Methods:

• Analysis of well-preserved fossil footprints from Late Triassic redbeds in Argentina.
• Comparative ichnological analysis to identify avian characters.
• Paleoenvironmental reconstruction of the depositional setting.

Main Results:

• Discovery of abundant footprints exhibiting clear avian characters.
• These tracks predate the earliest known bird skeletal fossils by at least 55 million years.
• The footprints suggest the presence of theropods with avian traits in the Late Triassic.

Conclusions:

• The findings push back the known origin of avian characters in theropods to the Late Triassic.
• Ichnology provides crucial evidence for understanding avian evolution.
• These tracks represent an unknown group of theropods with early avian affinities.