page_title: Tanis (fossil site)
section_title: Discovery and exploration of 'Tanis'
hierarchical_section_title: Tanis (fossil site) / Discovery and exploration of 'Tanis'
caption_attribution_description: English: Overview of the location of Tanis, and how the site is laid out.
context_page_description: Tanis is the name given to a site of paleontological interest in southwestern North Dakota, United States. Tanis is part of the heavily-studied Hell Creek Formation, a group of rocks spanning four states in North America renowned for many significant fossil discoveries from the Upper Cretaceous and lower Paleocene. Tanis is an extraordinary and unique site because it appears to record the events from the first minutes until a few hours after the impact of the giant Chicxulub meteor in extreme detail. This impact, which struck the Gulf of Mexico about 66 million years ago, wiped out all non-avian dinosaurs and many other species. The extinction event caused by this impact paved the way for the domination of the Earth by mammals, including human beings.
  The site was originally discovered in 2008 by University of North Georgia Professor Steve Nicklas and field paleontologist Rob Sula. Their team successfully removed fossil field jackets which contained articulated sturgeons, paddlefish and bowfins. These fossils were delivered for research to the Field Museum of Natural History in Chicago.
context_section_description: DePalma began excavating systematically in 2012 and quickly found the site to contain very unusual and promising features. Everything he found had been covered so quickly that details were exceptionally well preserved, and the fossils as a whole formed a very unusual collection – fish fins and complete fish, tree trunks with amber, fossils in upright rather than squashed flat positions, hundreds or thousands of cartilaginous fully articulated freshwater paddlefish, sturgeon and even saltwater mosasaurs which had ended up on the same mudbank miles inland (only about four fossilized fish were previously known from the entire Hell Creek formation), fragile body parts such as complete and intact tails, ripped from the seafish's bodies and preserved inland in a manner that suggested they were covered almost immediately after death, and – everywhere –millions of tiny spheres of glassy material known as microtektites, the result of tiny splatters of molten material reaching the ground. The microtektites were present and concentrated in the gills of about 50% of the fossilized fish, in amber, and buried in the small pits in the mud which they had made when they contemporaneously impacted. The fish were not bottom feeders. They had breathed in early debris that fell into water, in the seconds or minutes before death. The sediment appeared to have liquefied and covered the deposited biota, then quickly solidified, preserving much of the contents in three dimensions.
  Later discoveries included large primitive feathers 30–40 cm long with 3.5 mm quills believed to come from large dinosaurs; broken remains from almost all known Hell Creek dinosaur groups, including some incredibly rare hatchling and intact egg with embryo fossils; fossil pterosaurs for which no other fossils exist at that time; drowned ant nests with ants inside and chambers filled with meteor debris; and burrows of small mammals living at the site immediately after the impact. Analysis of early samples showed that the microtektites at Tanis were almost identical to those found at the Mexican impact site, and were likely to be primary deposits (directly from the impact) and not reworked (moved from their original location by later geological processes).
  DePalma quickly began to suspect that he had stumbled upon a monumentally important and unique site – not just "near" the K-Pg boundary, but a unique killing field that precisely captured the first minutes and hours after impact, when the K-Pg boundary was actually created, along with an unprecedented fossil record of creatures and plants that died on that day, as well as material directly from the impact itself, in circumstances that allowed exceptional preservation.
  When I saw [microtektites in their own impact craters], I knew this wasn’t just any flood deposit. We weren’t just near the KT boundary. This whole site is the KT boundary ... We have the whole KT event preserved in these sediments. With this deposit, we can chart what happened the day the Cretaceous died.
  — Robert DePalma
   
  It is truly a magnificent site ... surely one of the best sites ever found for telling just what happened on the day of the impact.
  — Walter Alvarez
  By 2013, he was still studying the site, which he named 'Tanis' after the ancient Egyptian city of the same name, and had told only three close colleagues about it. Tanis' secrecy was maintained until disclosed by DePalma and co-author Jan Smit in two short summary papers presented in October 2017, which remained the only public information before widespread media coverage of the full prepublication paper on 29 March 2019.
caption: Tanis location, schematic layout, and photo, showing: (1) Impact event deposits, covering (2) the slope of a prograding point bar of a river meander (bend). (3) Densest accumulations of fossil carcasses. (4) K-Pg boundary tonstein which directly overlays the impact deposit, and (5) directly overlays the adjacent river overbank. (6) location of Brooke Butte, the closest K-Pg outcrop to Tanis.Inset: Tanis at time of impact. The site is some miles from a large inland sea connected to the Gulf of Mexico.From DePalma et al. 2019
exif: {"Image Orientation": "Horizontal (normal)"}