Fossil plants and global warming at the Triassic-Jurassic boundary

Science

Volumn 285, Issue 5432, 1999, Pages 1386-1390

  McElwain, J C ^a   Beerling, D J ^a   Woodward, F I ^a  

^a UNIVERSITY OF SHEFFIELD   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

CARBON DIOXIDE;

FLORA; GLOBAL WARMING; JURASSIC; MASS EXTINCTION; PALEOCLIMATE; TRIASSIC; VEGETATION;

ARTICLE; BOTANY; CARBON DIOXIDE MEASUREMENT; ENVIRONMENTAL MONITORING; FOSSIL; GREENHOUSE EFFECT; PRIORITY JOURNAL; TURNOVER TIME;

EID: 0033609999     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.285.5432.1386     Document Type: Article

References (45)

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30. 2) where ΔT is the difference in mean global surface air temperature. The estimates will be somewhat dependent on the responses of the thermohaline circulation [E. Barrera et al., Geology 25, 715 (1997)].
31. 2) where ΔT is the difference in mean global surface air temperature. The estimates will be somewhat dependent on the responses of the thermohaline circulation [E. Barrera et al., Geology 25, 715 (1997)].
32. 2 [J. L. Sarmiento and J. R. Toggweiler, Nature 308, 621 (1984)]. Isotopic evidence supports a reduction in oceanic productivity at the T-J boundary (8); however, the data are equivocal because of potential diagenetic effects (8, 9).
33. 3 of basalt.
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35. -1) and close to daily maximum temperatures are reached. This approach was used to estimate relative maximum leaf size during the period of study (Fig. 3).
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37. The threshold for thermal damage of nonsucculent leaves (45° to 52°C) is a highly conserved characteristic across a wide range of extant taxa [W. Larcher, in Ecophysiology of Photosynthesis, E. D. Schultze and M. M. Caldwell, Eds. (Springer-Verlag, Berlin, 1994), pp. 261-277; Y. Gauslaa, Holarct. Ecol. 7, 1 (1984)], implying little evolutionary change through time.
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40. The cause of T-J floral turnover has traditionally been attributed to a sedimentary hiatus (3). However, this hypothesis is unsupported by sedimentological evidence [G. Dam and F. Surlyk, Geology 20, 749 (1992); Spec. Publ. Int. Assoc. Sedimentol. 18, 4189 (1993)], which identifies no major facies changes or unconformities between the T-J strata in Greenland. Furthermore, the absence of the upper Rhaetian Ricciisporites-Polypodisporites acme zone [W. M. L. Schuurman, Rev. Palaeobot. Palynol. 23, 159 (1977)] in Greenland (10) and Sweden (11), which has also been tentatively interpreted as evidence of a hiatus at both localities, is questionable, as acme zones are generally considered of only local use, owing to the effects of ecological, environmental, and postdepositional processes on relative pollen abundances.
41. The cause of T-J floral turnover has traditionally been attributed to a sedimentary hiatus (3). However, this hypothesis is unsupported by sedimentological evidence [G. Dam and F. Surlyk, Geology 20, 749 (1992); Spec. Publ. Int. Assoc. Sedimentol. 18, 4189 (1993)], which identifies no major facies changes or unconformities between the T-J strata in Greenland. Furthermore, the absence of the upper Rhaetian Ricciisporites-Polypodisporites acme zone [W. M. L. Schuurman, Rev. Palaeobot. Palynol. 23, 159 (1977)] in Greenland (10) and Sweden (11), which has also been tentatively interpreted as evidence of a hiatus at both localities, is questionable, as acme zones are generally considered of only local use, owing to the effects of ecological, environmental, and postdepositional processes on relative pollen abundances.
42. The cause of T-J floral turnover has traditionally been attributed to a sedimentary hiatus (3). However, this hypothesis is unsupported by sedimentological evidence [G. Dam and F. Surlyk, Geology 20, 749 (1992); Spec. Publ. Int. Assoc. Sedimentol. 18, 4189 (1993)], which identifies no major facies changes or unconformities between the T-J strata in Greenland. Furthermore, the absence of the upper Rhaetian Ricciisporites-Polypodisporites acme zone [W. M. L. Schuurman, Rev. Palaeobot. Palynol. 23, 159 (1977)] in Greenland (10) and Sweden (11), which has also been tentatively interpreted as evidence of a hiatus at both localities, is questionable, as acme zones are generally considered of only local use, owing to the effects of ecological, environmental, and postdepositional processes on relative pollen abundances.
43. std)] - 1} × 1000 where unk the ratio of unknown to sample and std is the ratio of the pee dee belemnite standard.
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45. 13C. We gratefully acknowledge funding from the Natural Environment Research Council, UK (GR9/02930), and through Royal Society Research Fellow and Equipment grants to D.J.B.