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Cited by 230Paleontology and Stratigraphy of FossilsPaleontology and Evolutionary BiologyEvolution and Paleontology Studies

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Asteroid impact, not volcanism, caused the end-Cretaceous dinosaur extinction

Open access
Chiarenza, Alfio Alessandro, Farnsworth, Alexander, Mannion, Philip D., Lunt, Daniel J., Valdes, Paul J., Morgan, Joanna V., Allison, Peter A.·2020·Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.2006087117PMC PMC7382232
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Abstract

Significance: We present a quantitative test of end-Cretaceous extinction scenarios and how these would have affected dinosaur habitats. Combining climate and ecological modeling tools, we demonstrate a substantial detrimental effect on dinosaur habitats caused by an impact winter scenario triggered by the Chicxulub asteroid. We were not able to obtain such an extinction state with several modeling scenarios of Deccan volcanism. We further show that the concomitant prolonged eruption of the Deccan traps might have acted as an ameliorating agent, buffering the negative effects on climate and global ecosystems that the asteroid impact produced at the Cretaceous–Paleogene boundary.

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Overview

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Written by AI from the paper’s full text.

TL;DR

Combining climate and habitat suitability models, this study finds that a Chicxulub asteroid impact winter produced extinction-level loss of non-avian dinosaur habitat, whereas modeled Deccan volcanism scenarios did not. Deccan CO₂ release may instead have buffered post-impact cooling and accelerated ecological recovery.

Key findings

  • Solar dimming scenarios reduced dinosaur habitat: 5% dimming left potential habitat at 4% and 24% of pre-K/Pg values at suitability thresholds 0.5 and 0.3, respectively; 10% dimming reduced habitat to 0.4% at the 0.3 threshold; habitat was extinguished at ≥15% dimming.
  • Deccan CO₂ warming increased maximum dinosaur habitat suitability by ∼120% at 1,120 ppm CO₂ and ∼97% at 1,680 ppm CO₂ in Ensemble models, and by ∼27% and ∼32% in MaxEnt, so long-term Deccan volcanism alone could not explain complete dinosaur habitat disruption.
  • Transient asteroid aerosol experiments produced >34 °C global mean cooling over the 6-y aerosol period, peak land surface cooling of −34.7 °C globally within 5 y, and >85% reduction in land precipitation, causing an extinction-level event for the non-avian dinosaur climatic niche.
  • Climate recovery took around 30 y, accelerated by ∼10 y with Deccan-derived CO₂; an ash layer over North America offset ∼4–5 °C of land surface cooling. With active volcanism, maximum habitability increased 152% from preimpact levels after recovery.

Methods

  • Used the coupled atmosphere–ocean GCM HadCM3L-M2.1 with end-Cretaceous boundary conditions and 560 ppm CO₂ baseline, running decoupled and transient scenarios including 5–20% solar dimming, 1,120/1,680 ppm CO₂, and 100× Pinatubo aerosol forcing with/without ash and Deccan CO₂.
  • Assembled a late Maastrichtian (69–66 Ma) global dinosaur fossil-occurrence dataset from the Paleobiology Database, cleaned to 2,088 entries across nine clades.
  • Modeled habitat suitability using Ensemble modeling in biomod2 and MaxEnt, with predictors limited to warmest/coldest annual quartile temperatures and wettest/driest yearly quarter precipitation after removing collinear variables (Pearson’s r ≥ 0.7).

Limitations

  • The paper states that chemical processes were not simulated and could further lead to habitat loss; the precise amount of Deccan CO₂ released is unknown; and the pace and magnitude of Deccan volcanism remain uncertain.
  • The authors state they do not discount biotic effects or other untested abiotic drivers (e.g., wildfire, acid rain, acidification, halogens, ultraviolet radiation, carbon cycle disruption), and they note that a deep-ocean impact scenario involving stratospheric water vapor was not tested.
  • Evident from the text: habitat suitability models rely on analogy with crocodiles and birds and on fossil occurrence data, and the Deccan CO₂ scenarios are described as conservative/extreme and likely unrealistic in amount, so the modeled volcanic buffering effect depends on uncertain forcing assumptions.

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Integrity signals

Registry

Crossref · 10.1073/pnas.2006087117

Cites

94 of 95 references verified0 citation errors · 0 not checkable

Statistics

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Figures

Fig. 1. Geologic (A) and paleontological (B) records of the K/Pg mass extinction. Paleothermometer (A) showing the Deccan-induced warming with the two main episodes of volcanism highlighted by the black arrows and symbols of volcanoes. The last phase extends beyond the end of the Cretaceous, characterized by the bolide impact in Chicxulub. Fossil remains of non-avian dinosaurs (body fossils, egg fragments, and nesting sites) occur throughout the whole stratigraphic record of prolonged volcanism episodes (dinosaur silhouettes). Numbers represent upper Maastrichtian dinosaur bearing localities, mapped on a late Maastrichtian paleogeography in B. 1, Hell Creek Formation (United States); 2, Lameta Formation (India); 3, Tremp Formation (Spain); 4, Phosphorite beds (Morocco); 5, Marilía Formation (Brazil); 6, Nemegt Formation (Mongolia). Dinosaur silhouette image credit: Phylopic/Jack Mayer Wood, which is licensed under CC BY 3.0.
Fig. 1. Geologic (A) and paleontological (B) records of the K/Pg mass extinction. Paleothermometer (A) showing the Deccan-induced warming with the two main episodes of volcanism highlighted by the black arrows and symbols of volcanoes. The last phase extends beyond the end of the Cretaceous, characterized by the bolide impact in Chicxulub. Fossil remains of non-avian dinosaurs (body fossils, egg fragments, and nesting sites) occur throughout the whole stratigraphic record of prolonged volcanism episodes (dinosaur silhouettes). Numbers represent upper Maastrichtian dinosaur bearing localities, mapped on a late Maastrichtian paleogeography in B. 1, Hell Creek Formation (United States); 2, Lameta Formation (India); 3, Tremp Formation (Spain); 4, Phosphorite beds (Morocco); 5, Marilía Formation (Brazil); 6, Nemegt Formation (Mongolia). Dinosaur silhouette image credit: Phylopic/Jack Mayer Wood, which is licensed under CC BY 3.0.CC BY-NC-ND · PubMed Central
Fig. 2. K/Pg surface temperature (degrees Celsius) outputs from GCMs. Heat maps represent temperature fluctuations from the late Maastrichtian control, with cooler temperatures in blue and warmer temperatures in red. Late Maastrichtian climate control (A) is perturbed in B by a solar dimming simulation reproducing the effect of mild asteroid impact or extreme volcanism-induced cooling (B) at 5% (scenario 1) and of a more extreme asteroid-induced cooling scenario (C) at 10% (scenario 2) of solar radiation reduction. The effect of prolonged volcanism is reproduced with an increase to 1,120 ppm of (D) CO2 content (scenario 5) and to (E) 1,680 ppm of CO2 (scenario 6). A transient model including both Deccan volcanism and the effect of the Chicxulub impact is shown in F (scenario 11) and G (scenario 12), and with inactive volcanism (H, scenario 13 and I, scenario 14), while the three coldest years of the impact are modeled in F (scenario 11) and H (scenario 13) (additional details and figures on GCMs are in SI Appendix). Temperature scale runs from −40 °C to 40 °C.
Fig. 2. K/Pg surface temperature (degrees Celsius) outputs from GCMs. Heat maps represent temperature fluctuations from the late Maastrichtian control, with cooler temperatures in blue and warmer temperatures in red. Late Maastrichtian climate control (A) is perturbed in B by a solar dimming simulation reproducing the effect of mild asteroid impact or extreme volcanism-induced cooling (B) at 5% (scenario 1) and of a more extreme asteroid-induced cooling scenario (C) at 10% (scenario 2) of solar radiation reduction. The effect of prolonged volcanism is reproduced with an increase to 1,120 ppm of (D) CO2 content (scenario 5) and to (E) 1,680 ppm of CO2 (scenario 6). A transient model including both Deccan volcanism and the effect of the Chicxulub impact is shown in F (scenario 11) and G (scenario 12), and with inactive volcanism (H, scenario 13 and I, scenario 14), while the three coldest years of the impact are modeled in F (scenario 11) and H (scenario 13) (additional details and figures on GCMs are in SI Appendix). Temperature scale runs from −40 °C to 40 °C.CC BY-NC-ND · PubMed Central
Fig. 3. Ensemble habitat suitability models (averaged) projected globally for nine clades of non-avian dinosaurs (additional details and figures on habitat suitability models are in SI Appendix). Blue color represents low level of habitat suitability (0), while red color represents high habitability (1,000). Habitat suitability models trained on the late Maastrichtian record and GCMs control (A) are then projected to decoupled solar dimming scenarios with 5% (scenario 1) of solar reduction (B) and (scenario 2) 10% of solar reduction (C). A climatic scenario modeling two different levels of greenhouse enrichment due to the Deccan volcanism is reported in D (scenario 5) and E (scenario 6). The effect on the dinosaur-suitable habitats for two transient simulations with Deccan volcanism inactive (F, scenario 11 and G, scenario 12) and active (H, scenario 13 and I, scenario 14) shows the dynamic response of global dinosaur habitability during the impact (F, scenario 11 and H, scenario 13) and throughout the recovery (G, scenario 12 and I, scenario 14).
Fig. 3. Ensemble habitat suitability models (averaged) projected globally for nine clades of non-avian dinosaurs (additional details and figures on habitat suitability models are in SI Appendix). Blue color represents low level of habitat suitability (0), while red color represents high habitability (1,000). Habitat suitability models trained on the late Maastrichtian record and GCMs control (A) are then projected to decoupled solar dimming scenarios with 5% (scenario 1) of solar reduction (B) and (scenario 2) 10% of solar reduction (C). A climatic scenario modeling two different levels of greenhouse enrichment due to the Deccan volcanism is reported in D (scenario 5) and E (scenario 6). The effect on the dinosaur-suitable habitats for two transient simulations with Deccan volcanism inactive (F, scenario 11 and G, scenario 12) and active (H, scenario 13 and I, scenario 14) shows the dynamic response of global dinosaur habitability during the impact (F, scenario 11 and H, scenario 13) and throughout the recovery (G, scenario 12 and I, scenario 14).CC BY-NC-ND · PubMed Central
Fig. 4. Histogram showing areal amount of habitat suitability for different ensemble HSM averaged in each climatic-forcing scenario (Sc) for all of the clades used. A constant decrease from initial conditions (control) is observed in the solar dimming models (Sc 1, 5% and Sc 2, 10%). A habitability increase is caused by ×4CO2 (Sc 5) and ×6CO2 (Sc 6) addition. A transient model shows the habitability decrease during the impact-related climatic perturbation and consequent recovery without Deccan volcanism (Sc 11 and 12) and with active volcanism (Sc 13 and 14). (Inset) Maximum thresholds of HSM outputs projected in each Sc.
Fig. 4. Histogram showing areal amount of habitat suitability for different ensemble HSM averaged in each climatic-forcing scenario (Sc) for all of the clades used. A constant decrease from initial conditions (control) is observed in the solar dimming models (Sc 1, 5% and Sc 2, 10%). A habitability increase is caused by ×4CO2 (Sc 5) and ×6CO2 (Sc 6) addition. A transient model shows the habitability decrease during the impact-related climatic perturbation and consequent recovery without Deccan volcanism (Sc 11 and 12) and with active volcanism (Sc 13 and 14). (Inset) Maximum thresholds of HSM outputs projected in each Sc.CC BY-NC-ND · PubMed Central

Verification

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Citations

Cites

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  1. 10.1093/condor/103.3.599 · DOI

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Metadata

Authors
Chiarenza, A. A., Farnsworth, A., Mannion, P. D., Lunt, D. J., Valdes, P. J., Morgan, J. V., & Allison, P. A.
Affiliations
  • University College London (GB)
  • School of Geographical Sciences, University of Bristol, BS8 1TH Bristol, United Kingdom
  • University of Bristol (GB)
  • Imperial College London (GB)
Corresponding author
Chiarenza, Alfio Alessandro
ORCID
Venue
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences
Published
2020-06-29
Volume
117
Issue
29
Pages
17084-17093
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
DOI
10.1073/pnas.2006087117
PMC
PMC7382232
OpenAlex
W3038551147
Cited by
228
References
94
Citations by year
2026: 24 · 2025: 32 · 2024: 32 · 2023: 36 · 2022: 65 · 2021: 29 · 2020: 9
FWCI
18.30
Type
journal article
Language
en
Open access
Licence
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • PubMed Central (publishedVersion, cc-by-nc-nd)
  • Bristol Research (University of Bristol) (publishedVersion, cc-by-nc-nd)
  • UCL Discovery (University College London) (submittedVersion)
  • Spiral (Imperial College London) (submittedVersion, other-oa)
Funders
Natural Environment Research Council (NE/P005217/1, NE/P013805/1, NE/K014757/1)
Topics
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Stratigraphy of Fossils
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Evolutionary Biology
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Evolution and Paleontology Studies
Keywords
end-Cretaceous mass extinction, dinosaur extinction, Chicxulub impact, impact winter, Deccan Traps, Deccan volcanism, Cretaceous-Paleogene boundary, climate modeling, ecological modeling, extinction scenarios
MeSH terms
Animals, Carbon Dioxide, Climate, Fossils, India, Mexico, Models, Biological, Paleontology, Minor Planets, Volcanic Eruptions, Dinosaurs, History, Ancient, Extinction, Biological

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