A newly described dinosaur fossil from Argentina is reshaping our understanding of early theropod evolution. Named Anteavis crurilongus, this small but agile predator lived approximately 231 million years ago during the Carnian stage of the Late Triassic—and it had features far more advanced than expected for its time.
A Fossil That Challenges the Timeline
Discovered in the Ischigualasto Formation of northwestern Argentina, the fossil includes cranial and postcranial remains that reveal a streamlined skull, elongated lower legs, and a compact, muscular hip structure. These traits were previously thought to belong only to much later neotheropods, suggesting that dinosaur evolution was more diverse and dynamic from the very beginning.
The genus name Anteavis means “before bird,” while crurilongus refers to its long legs—specifically, a femur that’s 80% the length of the tibia and a metatarsal III at 63% of tibial length. This anatomy points to a fast, ground-level hunter with efficient stride mechanics and lightweight bones built for speed.
Climate and Dinosaur Diversity
The fossil was found in a layer just above a level dated to 231 million years ago, in a region that experienced a shift from humid to semi-arid conditions. Researchers believe this climate change may have driven early dinosaur diversification, followed by a temporary decline in abundance around 228.91 million years ago. Fossil records show a rebound in diversity about 15 million years later during the Norian stage.
This pattern suggests that climate played a key role in shaping dinosaur evolution, with Anteavis representing a crucial data point in the early radiation of theropods.
Why It Matters
The discovery of Anteavis crurilongus expands the known anatomical spectrum of early theropods and challenges the idea that advanced features emerged gradually. Instead, it supports the view that early dinosaur evolution was marked by rapid experimentation and ecological adaptation.
Source: Phys.org – Early experiment at the dawn of dinosaur evolution discovered
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