文档介绍：letters to nature
18. Ahmad, N. in Pedogenesis and Soil Taxonomy II. The Soil Orders. Developments in Soil Science 11B survival’3 at the K/T boundary. By contrast, it has been argued
(eds Wilding, L. P., Smeck, N. E. & Hall, G. F.) 91–123 (Elsevier, New York, 1983).
19. Cerling, T. E. & Quade, J. in Continental Indicators of Climate (eds Swart, P., McKenzie, J. A. & that the fossil record refutes this hypothesis, placing a ‘big bang’
1,6
Lohman, K. C.) 217–231 (AGU monogr. 78, American Geophysical Union, Washington DC, 1993). of avian radiation only after the end of the Cretaceous .
20. Renne, P. R. et al. Intercalibration of standards, absolute ages and uncertainties in 40Ar/39Ar dating. However, other fossil data—fragmentary bones referred to extant
Chem. Geol. (Isot. Geosci. Sect.) 1–2, 117–152 (1998). bird lineages11–13—have been considered inconclusive1,6,14. These
21. Semaw, S. et al. million-year-old stone tools from Gona, Ethiopia. Nature 385, 333–338 (1997).
22. McIntosh, W. C. & Chamberlin, R. M. 40Ar/39Ar geochronology of Middle to Late Cenozoic data have never been subjected to ic analysis. Here we
ignimbrites, mafic lavas, and volcaniclastic rocks in the Quemado Region, New Mexico. Guidebook identify a rare, partial skeleton from the Maastrichtian of
New Mexico Geol. Soc. 45, 165–185 (1994). Antarctica15 as the first Cretaceous fossil definitively