Answer to Question 1
Two special conditions appear to be necessary: rapid burial and the possession of hard parts. When an organism perishes, its soft parts are usually quickly eaten by scavengers or decomposed by bacteria. Occasionally, however, the remains are buried by sediment. When this occurs, the remains are protected from the environment where destructive processes operate. Rapid burial, therefore, is an important condition favoring preservation. In addition, animals and plants have a much better chance of being preserved as part of the fossil record if they have hard parts. Although traces and imprints of soft-bodied animals, such as jellyfish, worms, and insects exist, they are not common. Flesh usually decays so rapidly that preservation is exceedingly unlikely. Hard parts, such as shells, bones, and teeth, dominate in the record of past life.
Answer to Question 2
It is issued when sustained winds of 199 kilometers (74 miles) per hour or higher are expected within a specified coastal area in 24 hours or less.
Model Organism Drosophila
Model Organism Neurospora
Fossil Size
The Number of Children Americans Think Are Ideal
Air flows through the PCV valve during idle, cruising, and light-load conditions.
Concordance Values for Common Medical and Behavioral Conditions in Humans