Evolution Test - 14

Precambrian is the largest span of time which starts from the origin of the earth to the start of the Cambrian period. This era is marked by the presence of different layers of sedimentary rocks.

The period of Earth 's history that began 2.5 billion years ago and ended 542.0 million years ago is known as the Proterozoic. Many of the most exciting events in the history of the Earth and of life occurred during the Proterozoic stable continents first appeared and  a long process taking about a billion years. Also coming from this time are the first abundant fossils of living organisms, mostly bacteria and archaea, but by about 1.8 billion years ago eukaryotic cells appear as fossils too. It is not the age of man. The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago till around 66 million years ago. It is also called the age of reptiles, a phrase introduced by the 19th century paleontologist Gideon Mantell. The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words meaning "entirely recent ". Thus, option B is correct.

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 419.2 3.2 Mya, to the beginning of the Carboniferous Period, about 358.9 0.4. It is named after Devon, England, where rocks from this period were first studied. The Devonian period experienced the first significant adaptive radiation of terrestrial life. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the "Age of Fish ". 

Therefore, the correct answer is option A.

The Rocky Mountains took shape during an intense period of plate tectonic activity that resulted in much of the rugged landscape of the western North America. The Laramide orogeny, about 80 –55 million years ago, was the last of the three episodes and was responsible for raising the Rocky Mountains.The Mesozoic Era lasted nearly 200 million years, starting and ending with mass extinctions. This era consisted of the Triassic, Jurassic, and Cretaceous Periods. The Mesozoic is thought to have had a warm climate that dinosaurs thrived in for 135 million years.

Dinosaurs are archosaurs, a larger group of reptiles that first appeared about 251 million years ago, near the start of the Triassic Period. Some other non-dinosaur reptiles are also archosaurs, including pterosaurs (the now-extinct flying reptiles) and modern crocodiles and their ancestors.

The evolution of birds and mammals occurred in Jurassic period. The earliest birds were derived from a clade of theropod dinosaurs named paraves. Mammals evolved 10 times faster in the middle of the Jurassic period.

The Mesozoic era is called the age of reptiles because this is when dinosaurs dominated the Earth. Dinosaurs rose to a dominant species at the end of the end of the Triassic Period and continued until the end of the Cretaceous period when a mass extinction occurred. This mass extinction killed off all of the dinosaurs and was one of the largest in the history of the Earth.

Mammals appeared on the earth long before the extinction of the dinosaurs; in fact, dinosaurs and mammals originated within 10 million years of each other, in the late Triassic about 200 million years ago.

The Cenozoic Era is also known as the Age of Mammals because the extinction of many groups of giant mammals, allowing smaller species to thrive and diversify because their predators no longer existed. Due to the large span of time covered by the period, it is beneficial to discuss the animal population by the milestone of the era rather than in generalities.

Hoofed animals like-horse orginated in Eocene epoch in North America. First  horse-like  animals from which the modern  horse Equus  evolved was  Hyracotherium  (old name  Eohippus). The fossil record is most complete in  horse.