A type of trilobite is used as an index fossil. These fossils were made about 540 million years ago. A scientist finds a trilobite fossil in layer 3 in the
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Describe the primary and secondary immune response in terms of speed and number of antibodies produced?

Up until 1938, paleontologists accepted the idea that coelacanths (an ancient fish) went extinct at the time that they last appear in the fossil record, about 80 million years ago. but in 1938, a live coelacanth was discovered off the coast of south africa that was compared to the fossil record and found to be the same species what goal of science does this discovery represent

What is the correct term for an area of rotating currents in an ocean? when ocean currents combine, they create an area of rotating currents called an