Essay about The Ancient Relatives of Mammals

A dinosaur has an antorbital fenestra with an open hole hip socket. The definition differs from the term used informally because it helped understand how the dinosaur moved and how they were categorized as species. There are four general characteristics that dinosaurs have as a result of their synapomorphies which are permeated acetabulum, ball-shaped head on proximal femur, the Cnemial crest on the proximial tibia, and an ascending process on astragalus. These four dinosaur synapomorphies are related to vertical limb support.

What makes a primate a primate? A primate is defined by its many incredible features. A primate is a mammal that has certain characteristics such as: flexible fingers and toes, opposable thumbs, flatter face than other mammals, eyes that face forward and spaced close together, large and complex cerebrum, and social animals. What makes a primate a primate is its characteristics. Some of the physical features primates are identified by is their teeth, snouts, eyes, ears, arms, legs, fingers, and toes. Human evolution is a big part of humans being primates, and having similar features and characteristics make humans to be considered to be a primate, but both humans and non-humans have differences.

There are numerous counts of evidence showing the processes of evolution and how species ultimately evolved over millions of years. One of the most compelling hypotheses behind evolution was presented by Charles Darwin with his study of the Galapagos Islands. His study showing the various different birds and their different evolutions they went through to be able to survive the changes of weather and relocation. The birds he studied had to change in order to survive, or as he simply puts it: “Survival of the Fittest”. Evolution is the changing of past organisms to diversify and have the ability to fit better in their environment and survive. Diving into the dinosaur cladogram, studies have shown that ancient dinosaurs, over hundreds of millions of years ago, evolved into our modern day birds, and not lizards as many suppose. It became apparent that there would not be enough food for a 9 ton dinosaur to consume on a daily basis forever. So evolution occurred and dinosaurs evolved to become more efficient so they could survive more effectively in their

Scientists say reptiles evolved from amphibians 340 million years ago. The first reptile was an insect eater. Reptiles were more adaptable and able to

Judging by the image of the magazine cover, this chapter will cover fossils as well as evolution. Perhaps it will talk about how land and water organisms are similar.

Mammals are a subcategory of vertebrates, and mammals are more closely related to each other than to other types of vertebrates. They are so closely related, in fact, that the pictures at Station 9, of embryos of different mammals, are nearly indistinguishable. They all seem to have developing vertebrae, heads, and limbs, that are identical. Some of these will be lost as the embryo develops. The human embryo will lose its tail, while the dolphin embryo will lose a large part of its limbs. Primates are a category of mammals, and apes are a type of primates. All apes come from a common ancestor, and that includes humans. Even humans speciated multiple times before the modern human, or homo sapiens, evolved, as evidenced by the skulls at Station 5. They were all skulls of different species of prehistoric human. The skull most similar to the modern skull belonged to the most recent species of human. There were times when two types of humans lived together. The species that was best adapted to fit the environment at the time survived, while the

The studies of primate evolution have been developing throughout the years and now scientists are able to compare and contrast between several types of primate groups. One notable primitive characteristic that non-human primates and human primates have retained is the development and evolution of their dentition. Due to primates having long growth periods, scientists are able to research how primates have different dental characteristics and specializations in modern time (Larsen, 2008). By analyzing teeth, scientists are able to determine several factors, such as similar dental formation, growth, development, and diet preferences (Larsen, 2008).

From both the title of the chapter and the introduction by Dr. Shubin, this chapter begins with a focus on teeth. Because the function of teeth is to break down food before it enters the esophagus, the different shapes of teeth can represent many different things about the organism it belongs to including what type of eater it was (carnivore, herbivore, or omnivore). Teeth are the hardest tissue (not bone) in the human body and therefore fossilize well. As Dr. Shubin stated in chapter one, there must be many points that permit a fossil to make any kind of scientific conclusion. Obviously, the state of their presence is important, so the fact that teeth preserve well allows for them to be great specimens for analysis. Dr. Shubin and his team analyzed fossilized teeth in areas as different as Nova Scotia and the Arizona desert. Studying different fossils in these diverse regions allowed the team to see that mammalian and reptilian teeth are very different. For example, mammalian teeth differ from organism to organism to fit with the organisms need (Cheetahs that eat only meat will have different teeth than deer who are herbivores) and are replaced only once in the lifetime of the organism while reptilian teeth are usually sharp and are constantly replaced if damaged. These differences allowed scientists to characterize fossils as either a reptile or a mammal. Similar to Tiktaalik discussed in chapter one, the discovery of fossils that were part reptile and part mammal allowed the researchers to see that mammals evolved from reptiles, and further supported the theory of evolution. Further studies yielded even more

Birds are closely related to crocodiles because they share the same ancestry with the dinosaurs. To compare the crocodile and lizard, one would think the lizard is closely related to crocodiles, as we read in our text, "similar structures don't always reveal common ancestry." Crocodiles and birds evolved having the same common ancestry as the dinosaur. Lizards, on the other hand, do not share a close common ancestor with crocodiles or dinosaurs, their common ancestry is more distant.

NOVA scienceNOW : 41 - First Primates is a video that mainly talks about Primates who are ancient ancestors of human beings. Primates came out on the Earth 55million years ago when dinosaurs extinct due to collision between an immense comet and the Earth. Plesiadapiform, which is a possibly the first ancestor of primates and human beings, firstly evolved with a mouse-size organism during 10 million years. It existed during the 10 million year with diverse evidences that can show its validity of first ancester of primates. Nails of plesiadapiforms is a critical evidence that they are early ancestors of primates. Secondary proof is a tube-like structure which is found in the middle ear. It happens to be a tube for a huge vessel that goes to the

It is estimated that mammoths had the largest biome on the plant at an estimated 1 square kilometer per mammoth (Zimov, 2014). Herbivores of the time ranged from under 45 kilograms to well over 1000 kg, making for a wide range of diversity within the speciation (graph below). While many of these mammals were preyed upon by the carnivores, some were simply too large to be killed by single predators, causing them to be relatively immune to predation (Rodriguez, Alberdi, Azanza, Prado, 2006).

40 million years ago the species Mesohippus celer appeared. It was taller than the Hyracotherium ( being 24 inches at the shoulder compared to 10-20 inches). They also didn't look as dog-like, because the back straightened slightly, the neck and legs grew a few inches, and the snout and face had grown longer. A close relative of the Mesohippus celer came to be, around 36 million years ago, called Miohippus assiniboiensis.

The fossil of Tiktaalik confirmed a major prediction of paleontology in that it showed characteristics of both aquatic animals, such as fish, and land animals, such as reptiles and amphibians. While it had fins and scales, it also had a flexible neck, a flat head, and complex bone structure in its fins that correspond with the structure of the legs of terrestrial animals. Thus, it demonstrates the evolutionary transition between aquatic and terrestrial life.

Eukaryotes come in two grades of organization: single-celled (protists) and multicellular (plants, animals, and fungi). The world today is full of complex multicellular plants and animals: how, why, and when did they evolve from protists?

They say as mammals continued to evolve, they drove the dinosaurs into extinction (“What Killed the Dinosaurs”). “Not only did mammals likely compete with dinosaurs for resources, many species survived the end-Cretaceous extinction and subsequently came to dominate Earth.” (“What Killed the Dinosaurs?”). This is primarily because the early mammals were a lot smaller than the mammals that exist today. “Some of the world's earliest mammals were the multituberculates, a group of small rodent like animals that first emerged on Earth about 165 million years ago.” (Welsh, Jennifer). Scientists predict that any mass extinction event that caused animals to go extinct affected larger animals than it did the smaller animals, such as mammals ("Dinosaurs Became Extinct 'due to Laying Eggs'"). Mammals remained small for almost 100 million years, while they out competed small and baby dinosaurs for food, shelter and resources until they were extinct. Once the dinosaurs were out of the way mammals were able to evolve and grow large in size like the mammals that exist today today (LiveScience). Fossil evidence sheds some light on this theory as well. Fossils of mammals believed to date back to about eighty five million years ago show that mammals began to change rapidly and grow. “This matches up with other mammal groups, including recently discovered species from the Late Cretaceous (between 100 million and 65 million years ago) showing highly specialized