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Leaf with fly

Image Not Available

Leaf with fly

Geography: USA, Colorado
Date: 1981
Dimensions:
length of leaf=5.5; width of leaf=1.5 cm
Taxonomy
    • Attributes
    • Objects
    • Taxonomy
    • KingdomPlantae
    • PhylumAngiospermophyta
Object number: 41760
Not on view
DescriptionAlthough past life was diverse, we rarely have a good window through which to examine it. The Green River Formation is one such window with its spectacular preservation of diverse fish, insects, and plants, and other animals. Here, we can view Wyoming during the Eocene, much as it was about 50 million years ago. The deposits represent a series of freshwater lakes. Algal blooms occasionally depleted the oxygen of one of the lakes, suddenly suffocating the fish. The dead fish (and occasionally other animals) sank and were covered by sediment that precipitated from the water due to the sudden change in water chemistry, Over the millennia, repeated blooms in one lake or another of this system created a buildup of abundant layers of thick, fossil-rich limestones. Most insects preserved in the Green River Formation are easily recognizable as types of insects with similar living representatives—crickets, flies, grasshoppers, beetles, dragonflies, bees, ants, and water striders. Although insects are much more numerous than other animals in terrestrial ecosystems, they are not as abundantly or well preserved. There are several reasons for this. Insects are usually quite small, with relatively delicate structures. Even their “hard parts,” their exoskeletons, are nowhere near as durable as bone. Generally, the insects preserved did not live in the lakes. Instead, they were mainly flying forms that accidentally dropped into a lake, and their remains would have had to survive a trip to the bottom before becoming buried and fossilized. Their small size introduces yet another bias—they are simply often overlooked by paleontologists looking for a bigger “prize!”
Collection:
Palaeobotany
Browse Categories:Fossils
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