Research Article

Exceptional continental record of biotic recovery after the Cretaceous–Paleogene mass extinction

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Science  22 Nov 2019:
Vol. 366, Issue 6468, pp. 977-983
DOI: 10.1126/science.aay2268
  • Fig. 1 Temporally calibrated stratigraphic, floral, and faunal data for the K–Pg interval in the Corral Bluffs study area (fig. S1).

    Stratigraphy is tied to the GPTS 2012 using paleomagnetics (P-mag) and CA-ID-TIMS U-Pb-dated ash (italicized dates) (20) (data S1 and figs. S3 and S5). The composite lithostratigraphic log (figs. S2 to S5) is dominated by intercalated mudstone and sandstone, reflecting a variety of fluvial facies. Pollen zones (data S3) are defined by diversification of Momipites spp. (fossil juglandaceous pollen) (Fig. 3I). The K–Pg boundary is demarcated by the decrease in abundance of Cretaceous pollen taxa (labeled “K-taxa”) without recovery, and the subsequent fern (Cyathidites spp.) spike (data S2). Relative abundance (%) of fern (Cyathidites spp.) and palm (Arecipites spp.) (Fig. 3E) palynomorphs increased considerably post-KPgE (data S2); note that palm pollen percentages are offset from scale by 20%. Standing richness of dicot morphospecies or megafloral standing richness is exclusive of species that occur at a single locality (data S4 to S7). Leaf-estimated mean annual temperature (LMAT) calibrated with East Asian forests (data S8 and fig. S6). Horizontal pink shading indicates hypothesized warming intervals. Estimated leaf mass per unit area (data S9 and S10 and fig. S7) is shown with box plots that represent the distribution of species-site pair means for each 30-m bin (supplementary materials). Box plots are placed along the y axis near each bin’s stratigraphic midpoint and are repositioned for visibility. See data S11 and supplementary materials for placement of NALMAs. Tick marks for P-mag, pollen zones, megafloral standing richness, and NALMAs show stratigraphic placement of samples and fossil localities (supplementary materials).

  • Fig. 2 Representative selection of vertebrate fossils.

    (A to L) Mammalian crania in dorsal and ventral views of Eoconodon coryphaeus [(A) and (B), DMNH.EPV.130976]; Ectoconus ditrigonus [(C) and (D), DMNH.EPV.130985]; Loxolophus sp. [(E) and (F), DMNH.EPV.132501]; juvenile E. ditrigonus [(G) and (H), DMNH.EPV.132515]; Carsioptychus coarctatus [(I) and (J), DMNH.EPV.95283]; and Taeniolabis taoensis [(K) and (L), DMNH.EPV.95284]. (M and N) Crocodilian cranium in dorsal and ventral view of cf. Navajosuchus [(M) and (N), DMNH.EPV.48541]. (O to T) Turtle crania in dorsal and ventral views of Axestemys infernalis [(O) and (P), DMNH.EPV.132514]; Palatobaena sp. [(Q) and (R), DMNH.EPV 134081]; and [(S) and (T)] Cedrobaena putorius (DMNH.EPV.130982). (U to X) Turtle shells in dorsal and ventral views of Gilmoremys sp. [(U) and (V), DMNH.EPV.95454] and Hoplochelys sp. [(W) and (X), DMNH.EPV.95453]. All crania and shells are shown to scale, except for (W) and (X), which are scaled 1:2 compared with the other specimens. Scale bar, 10 cm.

  • Fig. 3 Representative selection of plant fossils.

    (A) In situ tree stump. (B to E) Palm fossils, including (B) in situ stump, (C) frond, (D) flower (DMNH.EPI.45594), and (E) Arecipites sp. pollen grain. (F and G) Most common smooth and toothed dicot morphospecies: (F) “Rhamnus” goldiana (DMNH.EPI.52262) and (G) Platanites marginata (DMNH.EPI.23281). (H and I) Walnut family fruit and pollen: (H) Cyclocarya sp. (DMNH.EPI.52272) and (I) Momipites tenuipolus pollen grains preserved as a dyad. (J and K) Legume: (J) seedpod (DMNH.EPI.45540) and (K) leaflet (DMNH.EPI.45576). Rock hammer handle shown in [(A) to (C)] is 38 cm long; (D) flower is 5 mm wide; (E) pollen grain is 42 μm long; (I) each pollen grain has a 20-μm diameter; leaflet in (K) is scaled 2:1 compared with (J). Scale bar, 5 cm.

  • Fig. 4 Timeline of expansion of maximum body mass and niche space in earliest Paleocene mammals correlated with diversification and origination of key plant groups and warming intervals.

    Post-KPgE “disaster” ecosystems occur for <100 ka, ecosystem “recovery” occurs between ~100 and 300 ka, and overall post-KPgE ecosystem equilibrium occurs within ~300 ka. Mammalian body mass estimated on the basis of cranial and lower first molar dimensions of specimens recovered from Puercan 1 to Puercan 3 (Pu1–Pu3) intervals (data S13 and S14 and figs. S8 and S9). Data from Corral Bluffs study area (yellow) except for Pu1 mammals, which come from adjacent outcrops in the Denver Basin [West Bijou (orange), South Table Mountain (blue), and Alexander Locality (green)] and Didelphodon from North Dakota (red) (data S13 and S14 and supplementary materials). Not plotted is the distribution of other large (10 to 100+ kg) vertebrates (e.g., turtles, crocodilians, dinosaurs) found throughout the section (Fig. 1). Horizontal pink shading represents hypothesized warming intervals interpreted from LMAT. Niche partitioning graph showing environmental distribution of vertebrate groups (data S12): Carsioptychus, Ectoconus, and chelydroid turtles predominantly associated with floodplain and ponded water facies; baenid turtles and Taeniolabis predominantly in river channel complexes and proximal to medial crevasse splay facies. FAD, first appearance datum; m1, first molar tooth.

Supplementary Materials

  • Exceptional continental record of biotic recovery after the Cretaceous�Paleogene mass extinction

    T. R. Lyson, I. M. Miller, A. D. Bercovici, K. Weissenburger, A. J. Fuentes, W. C. Clyde, J. W. Hagadorn, M. J. Butrim, K. R. Johnson, R. F. Fleming, R. S. Barclay, S. A. Maccracken, B. Lloyd, G. P. Wilson, D. W. Krause, S. G. B. Chester

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Supplementary Text
    • Figs. S1 to S9
    • Table S1
    • References
    Data S1 to S14

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