Relative dating of fossils activity
Adaptations reflect how the plant deals with temperature, light and the availability of water and nutrients.Together, all these factors control how a plant grows.Wolfe went on to compare many combinations of leaf CLAMP is a very useful tool for researchers trying to identify palaeoenvironmental signals in fossil leaf assemblages.This approach has been successfully used on a number of occasions, with some recent examples including work on the Cretaceous floras (145 million to 65 million years old) from the high Arctic, and the Miocene flora of Yunnan, China.This means that plants can be used as proxies for the terrestrial conditions that prevailed when they were alive: data from fossil plants can be compared with records based on marine organisms and chemical isotopes to reconstruct past climates.Several methods have been developed that help us to interpret the climate signals stored in the plant fossil record; the most important of these are outlined below.
Thus, toothed margins apparently help plants in temperate regions to maximize their growth and productivity at the start of the growing season.
Leaf size is related to water loss: in hot, dry regions, plants have either no leaves or very small ones, whereas in wetter places, such as rainforests, leaves can get very large.
Wolfe showed that, in general, the shape of the leaf margin, or edge (Fig. The higher the proportion of plants with smooth (‘entire’) margins, the higher the temperature of the environment; leaves with toothed edges by contrast, tend to dominate in cooler climates.
It should be noted, however, that this approach depends on the accurate identification of the nearest living relative of a fossil, which can be problematic for some extinct lineages.
In addition, the more species used, the better: inferring past climates on the basis of multiple species is expected to yield more accurate results than doing so from just one.
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Temperate floras contain the highest proportion of leaves with toothed margins, and this proportion decreases with increasing temperature.