Terrestrial Mammals: A Comparative Essay

Trego works at the Conservation Ecology Lab at San Diego State University in California. She reported her team’s early findings on December 14, at the Society for Marine Mammalogy meeting in San Francisco.

Recent evidence suggests that whales may not have always inhabited the oceans. Bones of an ancient ancestor of modern day whales, the Basilosaurus, were discovered in Pakistan that suggest whales evolved from a wolf-like creature. This genus of an early whale lived 34-40 million years ago in the late Eocene. These fossils show many different features in common with both modern day whales and modern day land mammals. Since the discovery of these bones, many other evidences show that whales are a likely descendant of the Basilosaurus through many different ways, such as embryologic comparison and DNA testing. Whales aren’t the only suspected descendants

The Choloepus sloth is a rare but very interesting mammal. The sloth has an interesting diet, it only consumes of tough leaves, it could take up to a month for a sloth to digest its meal.The Sloths ancestors lived in North America. Sloths like sleeping in the fork of a tropical tree while curled into a ball. Another way that the sloths like to sleep would be by hanging from their feet from tree branches. “The two-toed sloth is slightly bigger than the three-toed sloth, though they share many of the same features. They are at around 23 to 27 inches (58 to 68 cm) and 17.5 to 18.75 pounds (about 8 kilograms)” (Bradford). Sloths are known to operate an entire habitat of invertebrate species that are similar to sloth fur.

Narwhals are considered to be the rarest mammals of the sea, the only species to belong in the genus Monodon. With their unique appearance, and dwindling existence, they are the least researched sea mammal; resulting in many unknowns of how Narwhals descended from the Beluga whale. From the family of Monodontidae, the narwhal evolved from the common ancestor Denebola. Their distinct feature, a tusk(which is in actuality a canine, the only tooth they possess), differentiates these creatures from other sea mammals, giving the species a selective advantage. The change in climate, scarcity in food, and fierce competition in sexual selection led to the significant evolution of Narwhals.

Abstract: Litocranius walleri (Brooke, 1879) is a rare, slender antelope commonly known as the gerenuk. A sexually dimorphic, even-toe ungulate identified by its extremely long neck and thin legs in proportion to the body, and is the only member of the genus Litocranius. It has been found in geographic locations including: Djibouti, Kenya, Tanzania, Ethiopia, and into southern Somalia. Considered diurnal, and resides in habitats areas of woody vegetation. L.walleri are browsers; feeding on foliage, leaves, fruits, and flowers. It is considered to be nearly threatened due to hunting and habitat degradation caused by livestock grazing and cutting of trees.

Bottlenose dolphins are known to use sea sponges as tools when foraging for food in the ocean. This behavior is referred to as “sponging”. “Sponging” refers to when these particular dolphins put a sea sponge over their rostrum (snout area) and use it to help collect food. Different explanations have been given as to why Bottlenose Dolphins engage in this behavior. It has been perceived that young dolphins learn this behavior from their mothers. Researchers are also exploring the option that a differentiation in diving skills exists between dolphins caused by variation in the mitochondrial genes processing of proteins that are involved in the creation of the Bottlenose Dolphins’ respiratory system, and that variation may have lead them to

Whenever people look around at God’s miraculous creation, the variety of animals is astounding. There are 5,416 different mammal species. Each mammal was created with a special purpose and way of living. All mammals share similar characteristics, including being warm-blooded, having a skeleton, growing hair, producing milk, and birthing live offspring. Despite sharing these characteristics, mammals differ in size, shape, and habitat. The smallest mammal, the shrew and the largest mammal, the blue whale still have similarities despite their vast size differences. Because there are so many various mammal species, their small differences are used to categorize the mammals into separate mammal orders. Artiodactyla is one out of the 26 mammal

Two lineages of sea turtle survived through the Eocene Epoch 55 to 38 millions years ago (Bowen 2003). One lineage was the predecessor of the leatherback turtle (Dermochelys coriacea), the only member of the family Dermochelyidae, and the other lineage gave rise to the six species of the family Cheloniidae, one of which is the loggerhead sea turtle (Bowen 2003). Today, only seven or eight species of marine turtles survive, distributed unevenly through all three tropical oceans. The modern decline in sea turtles species is not due to inherently poor adaption to post Pleistocene conditions, but is mainly a result of current and past anthropogenic exploitation. Additionally, the greater diversity of sea turtle taxa in the past compared to today is also due to the disappearance of entire isolated oceans such as the Nirobrara Sea, which was once inhabited by a diversity of seat turtle species. It is also due to other evolutionary mechanisms. Early sea turtle lineages had a growth of “experimental” type species that were more specialized, and these eventually became narrowed down to modern species as overspecialized species had a poor response to changing

The origin of modern day whales, a mystery that has puzzled paleontologists for years, may have just been solved with the discovery of an ankle bone. This discovery might sound simple and unimportant, but the bones of these ancient animals hold many unanswered questions and provide solid proof of origin and behavior. The relationship between whales and other animals has proven to be difficult because whales are warm-blooded, like humans, yet they live in the sea. The fact that they are warm-blooded suggests that they are related to some type of land animal. However, the questions of exactly which animal, and how whales evolved from land to water, have remained unanswered until now.

Ancestors of whales were "walkers" not swimmers as they are today. According to research by the University of Pisa, around fifty million years ago, whales walked the Earth. They had a small fox or wolf-like body that allowed them to walk across the land in search of food. They belonged to a family called

Whales (Cetacea) are unique among mammals in that they possess exceptionally dense, pachyosteosclerotic tympanic bullae1. Along the margin of the bulla is a highly mineralized, extremely dense wall of bone called the involucrum that serves as a special adaptation to life in the sea and as a means to facilitate sound reception and directionality underwater2,3,4. Moreover, this cetacean synapomorphy plays an important role in distinguishing its members from the ancestral terrestrial artiodactyls from which whales diverged5. When cut into cross-sections, the involucral region of the tympanic bullae in many mysticete (baleen whale) lineages reveals three easily distinguishable ‘zones’ of concentric laminar growth. Here we hypothesize that these three distinct zones identified along the length of the tympanic bullae are capable of recording life history events during early development, when the cetacean tympanoperiotic region is known to be rapidly ossifying6. We propose that the innermost zone (1) represents rapid in utero growth, the intermediary zone (2) represents rapid birth and postnatal development, and the outermost zone (3), markedly thinner, represents slower, more lamellar development from weaning on through adulthood.

The early Greek physicians-scientists Aristotle and Erasistratus were some of the first people to test on animals. Galen a Greek physician conducted animal experiments to advance the understanding of anatomy, physiology, pathology, and pharmacology. Ibn Zuhr a physician from the twelfth century tested surgical procedures on animals before performing them on human patients.

In 1923 a British-Indian scientist by the name of John Burdon Sanderson Haldane wrote a book in which he described what he thought were the six most important biological discoveries ever made. The last of the six discoveries, and perhaps the most controversial of them all, was the idea that the gestation of human fetuses could occur in an “unnatural” environment, i.e. an artificial womb. A word did not yet exist for this process and so Haldane coined the term ectogenesis. Ectogenesis is now defined in the Merriam-Webster dictionary as “development of a mammalian embryo in an artificial environment”. In 1923 the idea of raising a fetus in some sort of machine seemed extremely far-fetched, antibiotics wouldn’t even exist for another five years. However now it’s the year 2015 and we have organ transplants, artificial insemination/implantation, and cloning; ectogenesis has become a very real possibility. The issue is no longer about how plausible the idea is but rather if we, as human beings, should be considering ectogenesis as an option for future fetal incubation.

Vertebrates divide into many different groups, in particular my interest leans towards mammals, there are many different mammals they all come in different shapes and sizes. Mammals are animals who feed their young with milk which is produced by their mammary glands and unlike other animal’s mammals have hair and inner ear bones. Mammals are a well-known vertebrate species which include rodents, carnivores, herbivores, sea animals, hoofed animals, humans and others. Mammals range in size from as big as a whale or an elephant to as small as a mouse or a bat. Understanding mammals is much easier since humans themselves are mammals, since there are about 5000 different species of mammals it is hard to learn all of them.

There are plenty of organisms, and up till now mammals are the uttermost complicated organisms in the tree of life. Charles Robert Darwin was the one who believed that everything living on Earth was connected in some way or another and, even sketched the first ever tree of life. Evidence from morphological, biochemical, and gene sequence data suggest that all organisms on Earth are related some way or another. The genealogical relationships between all types of living things can be represented by a vast evolutionary tree called the tree of life. The tree of life is sort of like a family tree of all organisms. It is called the evolutionary tree due to it having an appearance of a tree that includes “branches” and “leaves”. The “branches” represent a genus, or a family. A genus is when a group of species is structurally similar or related. Than attached to the “branches” are the “leaves”, and the “leaves” represent the type of organisms that