Earth is the only known planet up to date which sustains life. A few millions years ago, Earth was home to the one of the most vicious and devastating creatures well-known to mankind ̶ dinosaur. Wrapped in a cocoon of evolution, Earth, along with most living beings, had endured metamorphosis, transforming the world to what it is now. Gigantic deadly dinosaurs went extinct, whilst only a minority that survived mutated into smaller-sized animals. Animals that roam the Earth are classified into three major categories, namely mammals, reptiles and amphibians, where each category is further divided into their respective orders (refer to Figure 1 in Appendix 1).
The first major type of animal is mammal. There are more than 4,000 different species of mammals. The smallest is the hog-nosed bat, which weighs 0.05 ounces. The largest is the blue whale, which can be 100 feet long and weigh 150 tons. But whether they live on land or water, all mammals share some common characteristics. All mammals are vertebrates. They have either a backbone or a spine. Besides, all mammals are endothermic, also known as “warm-blooded”. They regulate their own body temperature which allows them to live in almost every climate on Earth. Mammals have hair or fur on their bodies. Furthermore, they produce milk to feed their babies. This allows them to spend more time with their young and teach them important skills they need to survive on their own.
As Peterson (2006) mentioned, the word mammal is derived from the milk-producing mammary glands that are unique to the class Mammalia. Mammals owe their spectacular success to many features. Many of the most important and most diagnostic mammalian characteristic serve to further intelligence and sensory ability, t...
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...alliday, 2002). Caecilian is a type of Gymnophionan.
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Scientists had some idea to the evolutionary process of whales. “It has always been clear that aquatic cetaceans must have evolved from terrestrial mammals and returned to the water, and the forelimbs of recent cetaceans still have the same general pattern as that of land mammals.” (Walking with Whales) It was known fact that land mammals and whales were related. However, the change from ancient whales to modern whales is drastic.
The story Jurassic Park, by Michael Crichton, starts off with Mike Bowman taking a vacation with his family on the coast of Costa Rica. As they cruise on their Land Rover, Tina, Bowman’s daughter, runs off after spotting three-toed bird tracks. Tina then encounters a big lizard that makes chirping sounds, and is attacked by it. She is later sent to the hospital, where Dr. Gutierrez is intrigued to find out about the lizard that bit her left arm. Gutierrez goes back to the beach where Tina was attacked, and finds the carcass of a brown-striped lizard. The carcass is sent to the Tropical Diseases Laboratory of Columbia University Medical Center, where it is examined and analyzed. Despite the efforts made, no one is able to identify the lizard’s species, so the carcass is later sent to the Museum of Natural History for further analysis.
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...ould estimate where they spent most of their time. By the length of the other skeletal bones, the size and shape of the animals could be determined, which also shared insight to its behavior. The largest primitive whales could indeed walk on land, but only did so for short periods because their legs could not take so much weight for long amounts of time. These behaviors allow scientists and paleontologists to understand even more as to how these fascinating and mysterious animals went from ruling on land to taking over the sea.
Whales are considered to be intelligent mammals, but they live in the water despite the fact that mammals evolved on land. Paleontologist Phil Gingerich has been studying the evolution of whales since 1978. In 1978, he and his team discovered a rock in Pakistan with a skull on the inside. The skull appeared to be a wolf-like animal upon first sight, but Gingerich noticed the distinct whale ear on the skull. The skull, which had characteristics of both whales and other mammals, was that of a common ancestor of the whale known as Pakicetus. Many scientists believe that Pakicetus resembled the seal in its appearance. Pakicetus could not be considered a whale, since its backbone and limbs do not have similar features to those of a whale. Therefore, it is considered an ancestor of the whale, since it has some features of the whale and some unique features (or features of other mammals). Today’s whales have mammalian characteristics, which prove that they have evolved from a common ancestor of the mammal. A whale’s fin also has traits that are common of many species. The fin seems to be similar to that of a fish, but the bones on the inside of the fin are similar to those on a bird’s wing, a monkey’s arm, and a frog’s limb. This seems to be proof that these organisms, and many others, all evolved from a common ancestor. Other proof that whales have evolved over time lies in Egypt in the Valley of Whales, where over 400 fossils of whales currently lie. The desert used to be a large sea that was home to a few kinds of whales. In the Valley of Whales, Gingerich discovered the Basilosaurus, which had small hind legs, toes, and a mobile knee and lived 35-41 million years ago. This fossil is considered to be a transitional fossil, since it ha...
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Earth has gone through five fully major extinctions before. We currently are in the process of Earth’s sixth mass extinction. This mass extinction is closely related in severity to the extinction of the dinosaurs. Earth’s extinctions are broken into three different areas. The first area was the large number of animals caught by hunter-gathers. The discovery of agriculture led to the second area of extinction, wildlife habitats. These wildlife habitats were destroyed due to humans starting to stay in one area.
Hyla versicolor, commonly know as the Gray Tree Frog or the Eastern Gray Tree Frog, is an amphibian that is referred to as the “Chameleon of the Frog world” (Craighead, 2004, p.1) because of its ability to change colors. “This frog was once thought to be the same species as the Cope’s Gray Tree Frog”. They can only be distinguished by their calls and the fact that the Cope Gray Tree Frog is diploid while the Gray Tree Frog is tetraploid (NPWRC, 2004). The Gray Tree Frog is classified as follows:
Shirihai, H. and B. Jarrett (2006). Whales, Dolphins and Other Marine Mammals of the World. Princeton, Princeton University Press. p.185-188.
Zacherl, Danielle. “Biology 171 Evolution and Biodiversity.” National Association of Research in Science Teaching 2007 Annual Meeting, New Orleans LA. (2007):n. page. Print.