A 1.2 million-year-old hyena den in Pakistan has revealed that the ancient environment was a complex mosaic of different habitats.
April 29, 2026
Original Paper
Ecological heterogeneity in the Early Pleistocene Siwaliks: insights from stable isotope analysis of fauna from the Haro River Quarry hyena den, Pakistan
SSRN · 6661880
The Takeaway
For a long time, the ancient Siwalik region was thought to be a uniform and unchanging landscape. Isotopic analysis of fossils found in a prehistoric hyena's lair has proven that it was actually a diverse mix of forests and grasslands. This variety allowed many different species to live side-by-side by occupying their own unique niches. This discovery gives us the first clear picture of how diverse and resilient these ancient ecosystems really were. It changes our understanding of how early mammals evolved and migrated through these complex environments. It reveals a hidden world that was far more vibrant than we previously believed.
From the abstract
The Haro River Quarry (~1.2 Ma), a cub-provisioning den of Pachycrocuta brevirostris in the western Siwaliks, is a bonebed that offers a snapshot of Early Pleistocene ecosystem structure at ~1.2 Ma. In this study, we analyze δ13Cenamel and δ18Oenamel from a diverse mammalian assemblage (Cervidae, Bovidae, Suidae, Hyaenidae, Mustelidae, and Hystricidae) preserved in the den to reconstruct local vegetation and herbivore dietary ecology. Isotopic results indicate a landscape dominated by C4 grassla