Temperate floras contain the highest proportion of leaves with toothed margins, and this proportion decreases with increasing temperature.The underlying causes of this link between leaf margins and temperature are not well understood.They are generally incapable of moving around, and so are totally dependent on the atmosphere and the soil or rock (substrate) on which they grow.
Fossils provide us with our only direct record of prehistoric life.
Studying them can help us to reconstruct the anatomy, behaviour and evolution of long-extinct organisms.
One way to use plants to learn about palaeoclimates is to identify the nearest living relative of a fossil (Fig.
2) and document its environmental tolerance, its relationship with the environment (its Miocene (5 million to 23 million years ago) of the Rhine area of Germany.
For interpreting climate signals, there are two parts of the plant that are especially useful: leaves and wood.
CLAMP is a statistical technique for decoding climatic signals from the Jack Wolfe (1936–2005), who studied the physiognomic features of leaves from modern flowering plants and correlated them with climate for different communities across the globe.
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.
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.