![Tanis: The Hour the Dinosaurs Died, in One Layer [OC]](https://external-preview.redd.it/k3Kj7j1uTeeYo0aGY-s0haB65mf3kITQqXjPFe5y1XQ.jpeg?width=140&height=112&auto=webp&s=f8fe4df7b5c869e9fcbbf43994b852cf72be6850)
Tanis: The Hour the Dinosaurs Died, in One Layer [OC]
Tanis is a fossil deposit in the Hell Creek Formation, southwestern North Dakota, that preserves the day the asteroid hit, 66 million years ago, 3,050 kilometres from the Chicxulub impact crater in Mexico. The site contains articulated paddlefish and sturgeon with impact-melt spherules wedged between their gill rakers, capped by an iridium- and shocked-quartz-rich clay layer that matches K-Pg boundary sites worldwide.
The deposit also tells us the season the dinosaurs went extinct (boreal spring, confirmed independently by two research teams), what kind of asteroid hit Earth (a carbonaceous chondrite from beyond Jupiter's orbit, based on ruthenium isotope analysis published in Science in 2024), and how a 10-metre surge of water reached an inland river within an hour of impact (seismically induced seiche from the Western Interior Seaway, not a direct tsunami).
The article covers the geology, the dating evidence, the seasonality debate, the impactor provenance, the LeVeque et al. 2024 surge modelling, and the Robert DePalma data-handling controversy and Manchester misconduct investigation. Full references included.