Fossils have been found deposited in an area that was once covered in ocean. The fossils are of invertebrates related to crustaceans. These arthropods are segmented. Over the course of ten million years, fossils indicate three distinct body segments for this lineage. However, suddenly, the body morphology changed and only two segments are indicated by evidence in the fossil record. Which scientific explanation(s) appropriately support the evidence described here? Select ALL that apply. A) The ocean levels fell, resulting in an ocean of higher salinity.
B) Punctuated equilibrium explains the changes observed for this species. C) Gradualism was the most likely mechanism of evolution occurring for this species. D) The species was exposed to dramatic changes in climate, ocean temperature, or selective pressures suddenly.
E) There were few selective pressures occurring on that species over the time period indicated by the fossils.