When an organism is buried quickly, there is less decay and the better the chance for it to be preserved. The hard parts of organisms, such as bones, shells, and teeth have a better chance of becoming fossils than do softer parts. One reason for this is that scavengers generally do not eat these parts.
Q. What are indicator fossils What are the symptoms?
Index fossil, any animal or plant preserved in the rock record of the Earth that is characteristic of a particular span of geologic time or environment. A useful index fossil must be distinctive or easily recognizable, abundant, and have a wide geographic distribution and a short range through time.
Table of Contents
- Q. What are indicator fossils What are the symptoms?
- Q. Why is the gastropod not an index fossil?
- Q. How are fossils used in determining geologic time?
- Q. What can fossils show?
- Q. What are the conditions for fossils to form?
- Q. What are four conditions required for fossilization?
- Q. Under what conditions would a fossil not form?
Q. Why is the gastropod not an index fossil?
Since the gastropod is not unique, it cannot be an index fossil. An index fossil must be found over a wide area of the Earth. Since the gastropod is widely spread, it cannot be an index fossil.
Q. How are fossils used in determining geologic time?
To establish the age of a rock or a fossil, researchers use some type of clock to determine the date it was formed. Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events.
Q. What can fossils show?
Fossils are the remains or traces of ancient life that are usually buried in rocks. Examples include bones, teeth, shells, leaf impressions, nests, and footprints. This evidence reveals what our planet was like long ago. Fossils also show how animals changed over time and how they are related to one another.
Q. What are the conditions for fossils to form?
Fossils are formed in different ways, but most are formed when a plant or animal dies in a watery environment and is buried in mud and silt. Soft tissues quickly decompose leaving the hard bones or shells behind. Over time sediment builds over the top and hardens into rock.
Q. What are four conditions required for fossilization?
Preservation of remains (protection against scavenging, erosion and environmental damage) High pressure to promote mineralisation of remains (i.e. turn hard body parts into fossilised rocks) Anoxic (low oxygen) conditions to protect against oxygen damage and prevent decomposition by saprotrophs.
Q. Under what conditions would a fossil not form?
Unless there is deposition, fossils cannot be preserved. Deposition on land is common only in river valleys. Fossils are fairly common in sediments deposited on river floodplains. Some ocean environments that support animal life are exposed to very strong currents and waves.
