Editing Experimentum crucis (section)

===Tanis fossil site===
{{main|Tanis (fossil site)}}
In the 21st century, the discovery of the [[Tanis (fossil site)|Tanis fossil site]], a killing field in the [[Hell Creek formation]] of North Dakota, proved that the [[K-T boundary]] (now known as the KPg, or the [[Cretaceous–Paleogene extinction event]])<ref name=KPg21stC /> was the same event (the [[Chicxulub impact]]) which killed off the [[dinosaur]]s. This [[impact event]] was previously hypothesized from the global existence of [[iridium]] deposits 
(a rare element on Earth). In this case, the existence of a [[microtektite]] layer raining down upon the multiple intermixed species (including a [[Triceratops]])<ref name=SD /> which were found at the site (the Tanis Konservat-Lagerstätte)<ref name=KPg21stC />{{rp|page 7}} served as the conclusive witness,<ref name=KPg21stC >{{Cite journal|doi = 10.1073/pnas.1817407116|title = A seismically induced onshore surge deposit at the KPG boundary, North Dakota|year = 2019|last1 = Depalma|first1 = Robert A.|last2 = Smit|first2 = Jan|last3 = Burnham|first3 = David A.|last4 = Kuiper|first4 = Klaudia|last5 = Manning|first5 = Phillip L.|last6 = Oleinik|first6 = Anton|last7 = Larson|first7 = Peter|last8 = Maurrasse|first8 = Florentin J.|last9 = Vellekoop|first9 = Johan|last10 = Richards|first10 = Mark A.|last11 = Gurche|first11 = Loren|last12 = Alvarez|first12 = Walter|journal = Proceedings of the National Academy of Sciences|volume = 116|issue = 17|pages = 8190–8199|pmid = 30936306|pmc = 6486721|bibcode = 2019PNAS..116.8190D|doi-access = free}}</ref>  as cited in ''Science Daily''.<ref name=SD >[https://www.sciencedaily.com/releases/2019/03/190329144223.htm University of California - Berkeley: (29 March 2019) 66-million-year-old deathbed linked to dinosaur-killing meteor]</ref> Based on the dating of the Tanis, the event occurred 65.76 million years ago  (± 0.15 My).<ref name=KPg21stC />