Answer: They existed for a short span of time.
Explanation:
Index fossils are also referred to as the indicator fossils and they are simply used to define the faunal stages.
Some of the characteristics possessed by the index fossils include:
• geographic distribution that's wide
• short vertical range
• rapid evolutionary trends.
Over 2/3 of the argicultural land is used
Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson's plum pudding model of the atom had negatively-charged electrons embedded within a positively-charged "soup."
The answer is; plankton
The major group of plankton that contribute to earth’ crude oil are phytoplanktons because of their great numbers – even though they are microscopic. They are the base of the food chains in the oceans because they are the main primary producers. Examples of phytoplankton are the dinoflagellates, cyanobacteria, diatoms and blue-green algae.
there are seven horizontal rows of elements called periods. The vertical columns of elements are called groups, or families.
