Ordovician, to a lesser degree throughout the Silurian and Devonian, and then again during the Carboniferous and earliest Permian. During these periods, different species of brachiopods independently assumed a similar morphology, and presumably mode of life, to species that had lived millions of years before. This phenomenon, known as homeomorphy, is explained by convergent evolution: when subjected to similar selective pressures, organisms will often evolve similar adaptations. Further examples of rapid evolutionary radiation can be observed among ammonites, which suffered a series of extinctions from which they repeatedly re-diversified; and trilobites which, during the Cambrian, rapidly evolved into a variety of forms occupying many of the niches exploited by crustaceans today. Recent examples A number of groups have undergone evolutionary radiation in relatively recent times. The cichlids in particular have been much studied by biologists. In places such as Lake Malawi they have evolved into a very wide variety of forms, including species that are filter feeders, snail eaters, brood parasites, algal grazers, and fish-eaters. Caribbean anoline lizards are another well-known example of an adaptive radiation. Grasses have been a success, evolving in parallel with grazing herbivores such as horses and antelope. See also Evolutionary fauna Adaptive radiation Nonadaptive radiation References Evolutionary biology terminology