Name and compare the heart valves found between the upper and lower chambers of the right and left

How do you date a sample of rock that you suspect as being one of the earliest on earth

According to this food web which of the following would be considered primary consumers

The image shows the evolution of a species of fish. a few fish from a population developed different social behaviors and evolved into different species. two fish according to the image, the fish underwent . the new species of fish had mating seasons that were different from that of the original fish. because of the differences in mating seasons, the fish underwent reproductive isolation. this mode of isolation would be .