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The changes you might observe in the fossil record that would indicate the occurrence of a mass extinction is the <span>disappearance and subsequent absence of many up till then long-established groups.</span>
It would have to have a density greater than the density of Mercury. For example, if an abject had a density of 14.5 g/cm^3, it would sink when put in Mercury. Hope this helps! :D
A virus's ability to infect an animal cell depends primarily upon the "<span>presence of receptor sites on the cell membrane"
Hope this helps!</span>
I think it is 60 i believe so
