The Earliest Remains of Grasses in the Fossil Record

Crepet, William L.; Feldman, Gwen D.

doi:10.2307/2445181

Cited by 92 publications

(53 citation statements)

References 16 publications

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“…Hypotheses 1 and 2 can be rejected because grass fossil pollen is recorded since, at least, the Palaeocene, and because it can be unambiguously assigned at the family level 11 . Hypothesis 3 seems the most convincing; before grasses became ecologically dominant, shrubs and herbs of asters, amaranths and Ephedra might have had the pioneering role in repopulating the vast and deforested late Miocene Patagonian landscapes.…”

Section: Discussionmentioning

confidence: 99%

Fossil pollen records reveal a late rise of open-habitat ecosystems in Patagonia

Palazzesi

Barreda

2012

Nat Commun

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The timing of major turnovers in terrestrial ecosystems of the Cenozoic Era has been largely interpreted from the analysis of the assumed feeding preference of extinct mammals. For example, the expansion of open-habitat ecosystems (grasslands or savannas) is inferred to have occurred earlier in Patagonia than elsewhere because of the early advent of highcrowned teeth (hypsodont) mammals B26 Ma ago. However, the plant fossil record from Patagonia implies another evolutionary scenario. Here we show that the dominance of key open-habitat species-amaranths, Ephedra, asters and grasses-occurred during the last 10 Ma, about 15 Ma later than previously inferred using feeding/habitat ecology of extinct mammals. This late rise of open-landscapes in southern South America brings into question whether the expansion of open-habitat vegetation could have been the prime factor of highcrowned mammal diversification.

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Section: Discussionmentioning

confidence: 99%

Fossil pollen records reveal a late rise of open-habitat ecosystems in Patagonia

Palazzesi

Barreda

2012

Nat Commun

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“…These molecular clock calibrations relied on a broad range of time points: the divergence of rice and maize (65 mya) (Crepet and Feldman 1991), monocots and dicots (200 mya) (Wolfe et al 1989) and conifers and angiosperms (285 mya) (Savard et al 1994). The monocot-dicot and conifer-angiosperm divergence dates are corroborated by independent molecular clock estimates at multiple loci (Wolfe et al 1989;Savard et al 1994).…”

Section: Introductionmentioning

confidence: 99%

The MADS-box floral homeotic gene lineages predate the origin of seed plants: Phylogenetic and molecular clock estimates

Purugganan

1997

J Mol Evol

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Abstract. Flower development in angiosperms is controlled in part by floral homeotic genes, many of which are members of the plant MADS-box regulatory gene family. The evolutionary history of these developmental genes was reconstructed using 74 loci from 15 dicot, three monocot, and one conifer species. Molecular clock estimates suggest that the different floral homeotic gene lineages began to diverge from one another about 450-500 mya, around the time of the origin of land plants themselves.

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“…Our studies on wheat evolution calibrate the clock by using 60 Mya for the divergence of Pooideae and Panicoideae. The separation of the major clades of grasses has been estimated at 55-83 Mya (15)(16)(17), whereas an unpublished study of six fossils yielded a date of 52 Ϯ 8 Mya (E. Kellogg, personal communication).…”

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confidence: 99%

Acc homoeoloci and the evolution of wheat genomes

Chalupská

Lee

Faris

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

150

162

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The DNA sequences of wheat Acc-1 and Acc-2 loci, encoding the plastid and cytosolic forms of the enzyme acetyl-CoA carboxylase, were analyzed with a view to understanding the evolution of these genes and the origin of the three genomes in modern hexaploid wheat. Acc-1 and Acc-2 loci from each of the wheats Triticum urartu (A genome), Aegilops tauschii (D genome), Triticum turgidum (AB genome), and Triticum aestivum (ABD genome), as well as two Acc-2-related pseudogenes from T. urartu were sequenced. The 2.3-2.4 Mya divergence time calculated here for the three homoeologous chromosomes, on the basis of coding and intron sequences of the Acc-1 genes, is at the low end of other estimates. Our clock was calibrated by using 60 Mya for the divergence between wheat and maize. On the same time scale, wheat and barley diverged 11.6 Mya, based on sequences of Acc and other genes. The regions flanking the Acc genes are not conserved among the A, B, and D genomes. They are conserved when comparing homoeologous genomes of diploid, tetraploid, and hexaploid wheats. Substitution rates in intergenic regions consisting primarily of repetitive sequences vary substantially along the loci and on average are 3.5-fold higher than the Acc intron substitution rates. The composition of the Acc homoeoloci suggests haplotype divergence exceeding in some cases 0.5 Mya. Such variation might result in a significant overestimate of the time since tetraploid wheat formation, which occurred no more than 0.5 Mya.acetyl-CoA carboxylase ͉ Triticeae ͉ grass

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The Earliest Remains of Grasses in the Fossil Record

Cited by 92 publications

References 16 publications

Fossil pollen records reveal a late rise of open-habitat ecosystems in Patagonia

Fossil pollen records reveal a late rise of open-habitat ecosystems in Patagonia

The MADS-box floral homeotic gene lineages predate the origin of seed plants: Phylogenetic and molecular clock estimates

Acc homoeoloci and the evolution of wheat genomes

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