Form And Function In Fossil Plants

From many plant fossils, it is possible to understand the relationship between form and function in ancient plants, that is, what advantages or limitations are imposed on the growth and development of a plant based on certain biomechanical properties? For example, are all arborescent (treelike) plants constructed of cells and tissue systems of the same type? If not, in what other ways can plants grow to tower over their neighbors? Studies of this type examine the anatomical and morphological properties of various fossil plants, often using computer simulations to model growth, in an attempt to better understand broad evolutionary patterns of plant growth, as well as changes in growth form through time (Niklas, 1992; Rowe and Speck, 1998; Niklas and Spatz, 2004; Niklas et al., 2006). Biomechanical studies have been especially useful in delimiting adaptations necessary for plants to move onto the land, including upright growth, size limitations, and the nature of the conducting strand (Niklas, 1986), and, once plants became established in terrestrial environments, the influences of gravity and wind on their reproduction (Niklas, 1998), and even aerodynamic features of pollen (Schwendemann et al., 2007). Factors such as plant size and form can also be examined over a broad spectrum of plant morphologies and thus offer insights as to why certain plants and plant groups have developed particular anatomical and morphological characteristics. Examining tree growth and other factors in extant plants has demonstrated that there are a variety of variables in play. Because fossils demonstrate a number of different growth forms that are not seen in modern plants, they offer a unique resource of data to allow paleobotanists to explore a host of intriguing biological questions. Fossil plants can also be used to infer developmental processes (Sanders et al., 2007). For example, Boyce and Knoll (2002) analyze the morphospace of numerous Paleozoic leaves representing various clades and show that leaf evolution follows the identical sequence of morphologies in all groups. Such an approach provides the ability to test hypotheses using living leaf development as a proxy for the leaves seen in various groups in the fossil record.

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