. The Dunesland heritage of Illinois. Sand dunes -- Illinois; Natural history -- Illinois. Ross: The Dunesland Heritage of Illinois 9 tology. If fossils are sufficiently well preserved that we can identify them at least to family or genus, fig. 8, we can deduce many ecological facts about the time or place in which the fossilized organisms lived —such as whether it was aquatic or terrestrial, humid or dry. All our evidence indicates that, within rather broad limits, like things have lived under about the same climatic conditions for the greater. Fig. 8.—An insect fossil from on iron nodule or
. The Dunesland heritage of Illinois. Sand dunes -- Illinois; Natural history -- Illinois. Ross: The Dunesland Heritage of Illinois 9 tology. If fossils are sufficiently well preserved that we can identify them at least to family or genus, fig. 8, we can deduce many ecological facts about the time or place in which the fossilized organisms lived —such as whether it was aquatic or terrestrial, humid or dry. All our evidence indicates that, within rather broad limits, like things have lived under about the same climatic conditions for the greater. Fig. 8.—An insect fossil from on iron nodule or concretion found at Mozon Creek, Illinois; hind wing of on ancestral mayfly, lithoneoro mirifica Carpenter. Actual length of wing about one-half inch. This fossil represents on insect that lived during the Pennsylvonian period, about 250 million years ago. (Photograph courtesy of Illinois State Museum.) part of their history. If a species has become adapted to different climatic conditions, almost invariably morphological changes of some kind have accompanied or followed the ecological change. The second great accumulation of evidence used in unraveling this past comes from investigating the relationships and present geographic distribution of existing forms of life. This evidence com- prises part of the field known as biogeography. If plant or animal groups are studied on a world basis, the relationships and present distribution give us indubitable evidence of at least some past move- ments of floras and faunas. A plant and an insect offer two dramatic examples of these movements. The plant is the eastern skunk cabbage. At present, this plant is known only from the temperate deciduous forest of eastern North America and the temperate deciduous forest of China. Because skunk cabbage seeds are not spread easily (unlike others, such as dandelion seeds, which may be carried long distances by wind), it does not seem possible that the species was spread adventitiously from one a
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