Did an asteroid really kill the dinosaurs?
The records confirm the Chicxulub impact matched the extinction in time and triggered it. Whether the Deccan eruptions were also a main driver is disputed, and the 2004 claim that the impact came too early is contradicted.
- ✓ ConfirmedTheoryThe impact caused the mass extinction, dinosaurs included
- DisputedTheoryDeccan volcanism was a main driver of the extinction
- ✓ ConfirmedFeb 2013Dating puts the impact and the extinction within 32,000 years of each other
The Chicxulub asteroid, the Deccan Traps eruptions in India, or a decline that had already begun: what the dating, the drill cores and the published papers show.
The question What killed the dinosaurs, and what do the records show?
What the records say
The documented story holds up: 14 of 14 timeline steps are Confirmed by the records (score 100).
3 theories checked: 2 disputed, 1 confirmed. A theory is rated by its key claim.
Hull’s and Chiarenza’s teams conclude the impact, not the volcanism, drove the extinction
confirmedConfirmed as a record of what this document says, not that it is true. See the step
Down the rabbit hole
The ground line is the documented timeline. Each tunnel is a theory that branches off it; every chamber is a step, coloured by how well the records support it. The deepest chamber is the theory’s key claim. Tap one to open it.
Main timeline
Oldest first- About 66 million years agoconfirmed
A mass extinction ends the age of the dinosaurs
Around three-quarters of Earth’s animals died out at the Cretaceous–Paleogene boundary, among them every dinosaur except the birds. It is one of the three largest mass extinctions of the past 500 million years.
T2Natural History Museum, 13 Jun 2018T1Chiarenza et al., PNAS, 2020abstractT2Schulte et al. review, Science, 2010abstractT2Science news feature, 12 Dec 2014Sources disagreeThe 2010 review dates the boundary to about 65.5 million years ago; the Natural History Museum gives 66.0 million years after later re-dating. - From about 250,000 years before the boundaryconfirmed
Huge volcanic eruptions flood western India with lava
These are the Deccan Traps. Zircon dating puts the start of the main phase about 250,000 years before the boundary, with more than 1.1 million cubic kilometres of basalt erupted in about 750,000 years.
- About 66 million years agoconfirmed
An asteroid strikes Chicxulub, on Mexico’s Yucatán Peninsula
The crater is about 150 kilometres across and now largely buried; the asteroid is thought to have been 10 to 15 kilometres wide. Drill cores from inside the crater record the rock laid down on the first day after the impact.
- Jun 1980confirmed
The Alvarez team finds an iridium spike at the boundary and proposes an asteroid impact
Limestones in Italy, Denmark and New Zealand showed iridium about 30, 160 and 20 times background at the extinction level. They proposed that dust from an asteroid about 10 kilometres wide darkened the sky worldwide.
T1Alvarez et al., Science, 1980abstract - 1991confirmed
Hildebrand and six co-authors propose Chicxulub as the boundary crater
Their paper in Geology is titled “Chicxulub Crater: A possible Cretaceous/Tertiary boundary impact crater on the Yucatán Peninsula, Mexico”. Only its title and authors were read here.
- 2 Mar 2004confirmed
Gerta Keller’s team says the impact came about 300,000 years before the extinction
From a core drilled inside the crater, Yaxcopoil-1, they concluded the impact “did not cause the end-Cretaceous mass extinction as commonly believed.” Whether the timing holds is rated in the Deccan branch.
T1Keller et al., PNAS, 2004abstract - Mar 2010confirmed
A 41-author review in Science concludes the Chicxulub impact triggered the extinction
It found a single ejecta layer linked to Chicxulub spread worldwide at the boundary, matching the onset of the extinctions. Keller and colleagues replied in Science on 21 May 2010 under the title “Evidence Overlooked”, and the review’s authors answered.
- Feb 2013confirmed
Dating puts the impact and the extinction within 32,000 years of each other
Argon-argon dates establish the synchrony. The authors add that the impact “likely triggered a state shift of ecosystems already under near-critical stress.”
T1Renne et al., Science, 2013abstract - 11 Dec 2014confirmed
New dating ties the main Deccan eruptions to the boundary
Schoene’s team, Keller among them, dated zircons from ash layers between the lava flows. Science’s news feature said the result countered claims that the lava came too early to have played any role.
- Oct 2015confirmed
A second team finds most Deccan lava came out after a change close to the impact
Argon-argon dates show a “state shift” in the eruptions within about 50,000 years of the impact, after which about 70% of the Traps’ volume erupted. The authors suggest the impact may have set it off.
T1Renne et al., Science, 2015abstract - 18 Apr 2016confirmed
Sakamoto, Benton and Venditti report dinosaurs were in long-term decline
Their statistical model found speciation was “ultimately exceeded by extinction rate tens of millions of years before the K-Pg boundary”, except among some specialised plant-eaters.
- Feb 2019confirmed
Schoene’s and Sprain’s teams publish conflicting Deccan timelines
Schoene’s team, Keller among them, found four high-volume eruptive periods, one starting tens of thousands of years before the impact. Sprain’s team found the Traps “did not erupt in three discrete large pulses” and about 75% erupted after the boundary.
T1Schoene et al., Science, 2019abstractT1Sprain et al., Science, 2019abstractSources disagreeThe two 2019 papers, in the same issue of Science, disagree on whether the eruptions came in pulses and on how much lava came before the boundary. - 9 Sep 2019confirmed
Cores from inside the crater record the first day after the impact
Expedition 364 recovered about 130 metres of impact melt rock and suevite laid down that day. The authors say charcoal points to impact wildfires and the cores support “rapid global cooling and darkness as extinction mechanisms.”
T1Gulick et al., PNAS, 2019abstract - 2020confirmed
Hull’s and Chiarenza’s teams conclude the impact, not the volcanism, drove the extinction
Hull’s team (January) found major outgassing began and ended “distinctly before the impact, with only the impact coinciding with mass extinction”. Chiarenza’s climate models (June) found the impact winter shrank dinosaur habitats while volcanic warming made habitats more suitable.
T1Hull et al., Science, 2020abstractT1Chiarenza et al., PNAS, 2020abstract
Branches
Go down oneA branch is only as strong as its weakest step so far. The count is how many sources back each step.
Volcanoes did it (the Deccan Traps)
Were the Deccan eruptions the real killer?
Science’s 2014 feature says scientists who favoured a gradual trigger such as volcanism met the 1980 impact idea coolly; Dewey McLean, a proponent of a volcanic cause, clashed with Luis Alvarez in the early 1980s. Keller took up the fight after moving to Princeton in 1984.
- 910,407 YouTube views, “The Most Dangerous Woman in Science Says We Got the Dinosaur Extinction Totally Wrong” (Today I Learned Science) as of 17 Oct 2026 T3YouTube: Today I Learned Science on Keller
- 6,237 YouTube views, Gerta Keller’s 2014 GSA talk on Deccan volcanism and the extinction as of 17 Oct 2026 T3YouTube: Keller’s 2014 GSA talk
The eruptions were enormous and went on through the extinction
The video says Keller spent 35 years arguing eruptions in the Deccan Traps “drove the mass extinction and not the asteroid.”
T3YouTube: Today I Learned Science on KellerdescriptionThe premise: confirmedTrue that they were vast and overlapped the boundary: both dating teams agree. That they caused the extinction is the disputed part.
T1Schoene et al., Science, 2015abstractT1Sprain et al., Science, 2019abstractThe impact came too early to be the killer
Keller’s 2004 paper put the impact about 300,000 years before the boundary; in 2012 she said “that impact was not big enough to cause a mass extinction”.
The premise: disprovenLater dating puts impact and extinction within 32,000 years, and the crater cores hold the boundary’s first day. No record read tests the size claim directly.
T1Renne et al., Science, 2013abstractT1Gulick et al., PNAS, 2019abstractLife was already under stress before the asteroid hit
Keller found foraminifera species falling sharply between eruptions, per a 2012 profile; her 2009 paper ties the extinction to the end of the main eruption phase in India.
The premise: disputedThe 2013 dating paper itself speaks of ecosystems “already under near-critical stress”. Hull’s 2020 team found only the impact coincided with the mass extinction.
T1Renne et al., Science, 2013abstractT1Hull et al., Science, 2020abstract
- confirmed
The Deccan eruptions were vast and overlapped the boundary
More than 1.1 million cubic kilometres of basalt in about 750,000 years, starting about 250,000 years before the boundary. Another team found more than 90% of the volume erupted in under a million years, about 75% after the boundary.
T1Schoene et al., Science, 2015abstractT1Sprain et al., Science, 2019abstractStartStrength so far:confirmed· 2 sources on this step - disproven
The impact came about 300,000 years before the extinction
Claimed by Keller’s team in 2004. Later argon-argon dating put impact and extinction within 32,000 years of each other, and cores from inside the crater hold the boundary’s first day.
T1Keller et al., PNAS, 2004abstractT1Renne et al., Science, 2013abstractT1Gulick et al., PNAS, 2019abstract▼ WeakerStrength so far:disproven· 3 sources on this step - disputed
Key claim: Deccan volcanism was a main driver of the extinction
For: Schoene’s 2019 dating supports models with “both catastrophic events as drivers”, and Renne’s 2015 team wrote that neither “can be considered in isolation”. Against: Hull’s 2020 team found the outgassing ended before the impact, and Chiarenza’s models found volcanic warming made habitats more suitable.
T1Schoene et al., Science, 2019abstractT1Renne et al., Science, 2015abstractT1Hull et al., Science, 2020abstractT1Chiarenza et al., PNAS, 2020abstract= HoldsStrength so far:disproven· 4 sources on this step
Bullshit meter
- The impact came about 300,000 years before the extinction. Disproven.
- Key claim contradicted by tier 1? Partly. Its 2004 timing argument is contradicted by later tier-1 dating, but whether the eruptions were a main driver is still argued in tier-1 papers on both sides.
Fluff meter: possibly planted
- Can’t be traced to an original record. Absent: traced to peer-reviewed papers by Keller and others.
- First appeared from new or anonymous accounts. Not measured.
- Coordinated identical wording. Not measured.
- Cited source doesn’t exist. Absent.
- Later contradicted. Present for the 2004 timing argument, contradicted by the 2013 dating and the 2019 crater cores.
● present · ○ absent · – not measured. Lists signals only. It never accuses anyone.
Personal interest meter
- Gerta Keller, the best-known advocate of the volcanism theory, is a co-author of both Schoene dating papers. T1Schoene et al., Science, 2019author list
“Has a documented interest” only, each one sourced. Never an implication of guilt.
Correlation meter
- Gerta Keller, co-author of the 2015 and 2019 Deccan dating papers (main timeline) and lead author of the 2004 timing claim (Deccan branch). T1Schoene et al., Science, 2019author list
- The 2013 argon-argon dating, is the evidence for the impact branch and the contradiction of the 2004 timing claim in the Deccan branch. T1Renne et al., Science, 2013abstract
Links to other cases appear once those cases exist.
Who worked on this
This case was assembled by the site from public records. Contributions are not open yet. Nothing here is invented, so the counts are zero.
This is the first published version of the case.
Sources
- T1Luis W. Alvarez, Walter Alvarez, Frank Asaro and Helen V. Michel, “Extraterrestrial cause for the Cretaceous-Tertiary extinction”, Science 208 (4448): 1095–1108, June 1980 (abstract read). doi.org · copy read: europepmc.org
- T1Alan R. Hildebrand, Glen T. Penfield, David A. Kring, Mark Pilkington, Antonio Camargo Z., Stein B. Jacobsen and William V. Boynton, “Chicxulub Crater: A possible Cretaceous/Tertiary boundary impact crater on the Yucatán Peninsula, Mexico”, Geology 19 (9): 867, 1991 (only the title and authors were read, from the Crossref record; the publisher page refused access). doi.org
- T1Gerta Keller, Thierry Adatte, Wolfgang Stinnesbeck and others, “Chicxulub impact predates the K-T boundary mass extinction”, PNAS 101 (11): 3753–3758, 2 Mar 2004 (abstract read). doi.org · copy read: europepmc.org
- T1Gerta Keller, Ashok Sahni and Sunil Bajpai, “Deccan volcanism, the KT mass extinction and dinosaurs”, Journal of Biosciences 34 (5): 709–728, Nov 2009 (abstract read). doi.org · copy read: europepmc.org
- T2Peter Schulte and 40 co-authors, “The Chicxulub asteroid impact and mass extinction at the Cretaceous-Paleogene boundary”, Science 327 (5970): 1214–1218, Mar 2010, a review of the published records (abstract read). doi.org · copy read: europepmc.org
- T1Gerta Keller, Thierry Adatte, Jose Pardo, Sunil Bajpai and Ashu Khosla, “Cretaceous Extinctions: Evidence Overlooked”, letter, Science 328 (5981): 974–975, 21 May 2010 (only the title, authors and date were read, from the Crossref record). doi.org
- T1Peter Schulte and co-authors, “Response—Cretaceous Extinctions”, Science 328 (5981): 975–976, 21 May 2010 (only the title, authors and date were read, from the Crossref record). doi.org
- T1Paul R. Renne, Alan L. Deino, Frederik J. Hilgen and six co-authors, “Time scales of critical events around the Cretaceous-Paleogene boundary”, Science 339 (6120): 684–687, Feb 2013 (abstract read). doi.org · copy read: europepmc.org
- T2Richard Stone, “Back from the dead” (news feature: “The once-moribund idea that volcanism helped kill off the dinosaurs gains new credibility”), Science 346 (6215): 1281–1283, 12 Dec 2014. doi.org · copy read: www.geo.vu.nl
- T1Blair Schoene, Kyle M. Samperton, Michael P. Eddy, Gerta Keller and four co-authors, “U-Pb geochronology of the Deccan Traps and relation to the end-Cretaceous mass extinction”, Science 347 (6218): 182–184, published online 11 Dec 2014 (abstract read). doi.org · copy read: europepmc.org
- T1Paul R. Renne, Courtney J. Sprain, Mark A. Richards and three co-authors, “State shift in Deccan volcanism at the Cretaceous-Paleogene boundary, possibly induced by impact”, Science 350 (6256): 76–78, Oct 2015 (abstract read). doi.org · copy read: europepmc.org
- T1Manabu Sakamoto, Michael J. Benton and Chris Venditti, “Dinosaurs in decline tens of millions of years before their final extinction”, PNAS 113 (18): 5036–5040, published online 18 Apr 2016 (abstract read). doi.org · copy read: europepmc.org
- T1Blair Schoene, Michael P. Eddy, Kyle M. Samperton, C. Brenhin Keller, Gerta Keller, Thierry Adatte and Syed F. R. Khadri, “U-Pb constraints on pulsed eruption of the Deccan Traps across the end-Cretaceous mass extinction”, Science 363 (6429): 862–866, Feb 2019 (abstract read). doi.org · copy read: europepmc.org
- T1Courtney J. Sprain, Paul R. Renne, Loÿc Vanderkluysen and three co-authors, “The eruptive tempo of Deccan volcanism in relation to the Cretaceous-Paleogene boundary”, Science 363 (6429): 866–870, Feb 2019 (abstract read). doi.org · copy read: europepmc.org
- T1Sean P. S. Gulick and co-authors, “The first day of the Cenozoic”, PNAS 116 (39): 19342–19351, published online 9 Sep 2019, on IODP-ICDP Expedition 364 drill cores from the Chicxulub crater (abstract read). doi.org · copy read: europepmc.org
- T1Pincelli M. Hull and co-authors, “On impact and volcanism across the Cretaceous-Paleogene boundary”, Science 367 (6475): 266–272, Jan 2020 (abstract read). doi.org · copy read: europepmc.org
- T1Alfio Alessandro Chiarenza, Alexander Farnsworth, Philip D. Mannion and four co-authors, “Asteroid impact, not volcanism, caused the end-Cretaceous dinosaur extinction”, PNAS 117 (29): 17084–17093, published online 29 Jun 2020 (abstract read). doi.org · copy read: europepmc.org
- T1Joseph A. Bonsor, Paul M. Barrett, Thomas J. Raven and Natalie Cooper, “Dinosaur diversification rates were not in decline prior to the K-Pg boundary”, Royal Society Open Science 7 (11): 201195, published online 18 Nov 2020 (abstract read). doi.org · copy read: europepmc.org
- T2Emily Osterloff, “How an asteroid ended the age of the dinosaurs”, Natural History Museum, London, 13 Jun 2018, quoting the Museum’s dinosaur researcher Professor Paul Barrett. www.nhm.ac.uk
- T2“Dinosaurs were not in decline before the asteroid wiped them out”, Natural History Museum, London, news, 18 Nov 2020 (on Bonsor et al. 2020). www.nhm.ac.uk
- T3Justine Hausheer, “Between the flows” (Gerta Keller’s controversial dinosaur-extinction theory), Scienceline, a project of NYU’s Science, Health and Environmental Reporting Program, 22 Jan 2012. scienceline.org
- T3“The Day the Dinosaurs Died – Minute by Minute”, Kurzgesagt – In a Nutshell, YouTube, 15 Jun 2021. www.youtube.com
- T3“How We Figured Out an Asteroid Killed the Dinosaurs”, PBS Eons, YouTube, 4 Nov 2025. www.youtube.com
- T3“The Most Dangerous Woman in Science Says We Got the Dinosaur Extinction Totally Wrong”, Today I Learned Science, YouTube, 1 Oct 2026. www.youtube.com
- T3“Gerta Keller on ‘Deccan volcanism, Chicxulub impact and the KTB mass extinction’”, GSA2014: Volcanism, Impacts, and Mass Extinctions, YouTube, 27 Nov 2014. www.youtube.com
- T3“Dinosaur Extinction Started 10 Million Years Before The Asteroid Hit”, Bright Side, YouTube, 21 Nov 2021. www.youtube.com