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.
For many animals, the ability to move is essential for survival. Animals move for a variety of reasons such as: to find food, a mate, a habitat to live in, or to escape predators. It is important for animals to develop new abilities and traits to accomplish these necessities of living. Natural selection has shaped the locomotion methods and mechanisms used by moving organisms for millions of years. Generally, non-human primates are studied to garner an understanding of evolution caused by natural selection because of the many distinctive adaptations that have occurred within their taxonomic order. To understand the origin of locomotion that exist amongst primates, the two categories of primates must be analyzed to recognize morphological trait differences. Then, three major determinants can be evaluated to describe the variety of locomotor patterns primates display: the ecological niches in which the primate originates, the current inhabited niches, and the major key aspects of survival such as
Subclass – Archeorinthes –*Fossil birds (Jurassic birds of Mesozoic Age). *Flight feathers present. *Long tail without a pygostyle. *Carpals and metacarpals free. *Abdominal ribs present. *Hand reduced to three digits.
The Australopithecine are some of the earliest known hominids and they embody many characteristics that are associated with bipedalism. Bipedalism is a highly specialized and unusual form of primate locomotion that sets modern humans apart from all other living primates as we are the only extant obligate bipeds. Many evolutionary biologists and paleoanthropologists have devoted innumerable research hours to attempting to understand this unique form of locomotion and how it evolved. A number of interdependent morphological adaptations occurred over a long period of time to solve challenges posed by habitual bipedalism. As a result, there are differences that exist between early and late hominin species.
Prud’homme et al. (2011) demonstrated that the wing specific gene nubbin was expressed in a similar pattern in the helmet formation as in wings and arrived at the conclusion that the treehopper helmet was serially homologous to the T1 wing. In addition the authors speculated that the evolution of the helmet is due to a change in an unknown genetic mechanism downstream of Scr (sex combs reduced), which is part of the hox gene family. Thereby suggesting that the evolution of the treehopper helmet is due to genes that were under repression by hox genes. Moczek (2011) speculated that the tree hoppers evolved a wing like structure through re- emergence of a repressed developmental program of the wing. Clark-Hachtel and Tomoyasu (2016) proposed that the treehopper helmet might be partially homologous to the wings based on the fact that the treehopper helmet and the beetle carinated margin of Tribolium beetle both originate from the T1 tergum and it was shown that the reduction of the repression of Scr lead to formation of wings in the beetle. Conversely Yoshizawa (2012), proposes that the lack of evidence for the Scr mechanism in treehoppers might be due to pleiotropy and
The passage reading claims some reasons for the pterosaurs that this kind of dinosaurs was not able to fly; despite of it had long wings. But, the professor finds all the reasons dubious and presents some evidences to refute them all.
Like Snakes, ostriches are another example of Vestigial Features. Ostriches have wings, but they dont use them to fly like othere birds. They use them to keep balance. Through the past, thier bodies and long legs have been enough to avoid predators. So if ostriches haved survived by running and kicking
Hummingbird feeding behaviour has evolved so that they hover in flight, however due to this behaviour they have lost the ability to use their feet which now only serve for perching. (Lotz, Nicolson 1996). They compensate for this devolution by alternating their wing angle during flight which in turn has allowed them to use less energetic output during flight (Gass & Garrison 1999). Another adaptation that hummingbirds have evolved to allow them to hover in midair is the rate at which they flap their wings. This unique flying behaviour has created specific skeletal and flight muscle adaptations such as a large keel and rigid weight bearing girdles which allows for greater muscle attachment from wing to abdomen and in turn an increase
In the current times, feathers are only found in birds and provide them a unique nature. Feathers vary in size, color, shape, and arrangement on the body of the birds. They are used for various purposes such as flight, insulation, beauty, swimming and floating, support when the birds are not flying and constructing nests. It is essential to understand the origin of feathers. Evidence of the existence of feathers can be dated back to one hundred and sixty million years ago during the Last Jurassic period (Chen et al., 2015). Long before birds used feathers for flying and for insulation purposes, some scientists believe, they were used by Epidexipteryx, a small dinosaur, for display and seduction of dinosaurs of the opposite sex. They first appeared
The (Grant and Grant 2006) discussed the intraspecific completion between the G. fortis and its opposing and larger competitor, the G. magnirostris. Character displacement in the finches can describe the evolutionary changes they went through. As proposed by Lack in this paper, character displacement caused G. fortis to evolutionary develops smaller beak sizes in order to consume smaller seeds. As smaller seeds were prevalent, finches would consume those as a food supply. As small seeds started to diminish, large seeds were the seed of choice for them. Unfortunately, they were not able to adapt their small bill size to break these large seeds, causing problems for them. Therefore, this can be stated as the hypothesis of the paper where Grant and Grant tried to show that the beak size of the G.fortis evolved and changed due to ecological factors like competitor
The Arboreal Hypothesis suggests that biped that are ground running had its adaptations in trees, such as leaping from tree to tree. Later on the feathers became important for jumping and parachuting. The cursorial hypothesis suggested that a reptile might transform or evolve scales on the arms. The scales could generate lift as the arms were flapping, thus making the animal take leaps which transformed into powered flapping flight.
Millions of years ago a dinosaur group, theropods, consisted of killing-machines like the T-Rex and the velociraptor, but recent research has proven that these bloodthirsty carnivores evolved into birds, trading their sharp teeth for beaks. This mind-blowing realization has confused many people for years, but Amy Balanoff reported her findings to show proof of the line of evolutionary descent from horrendous beast to feathery pet.
Pterosaurs have been long suspected that they were uncapable of powered flight which requires flapping their wings to fly. This is where the writer of the article stands on this issue, while the lecturer suggests otherwise by presenting a series of undiscovered facts, reasoning and reduction.
Evolution occurs when an animal species develops new bodily structures and functions in order to adapt to their new environment. These developments are seen as positive adaptations that enhances survival. However, some animal species have lost these new developments. Based on the geographic location and climate, some evolutionary developments that are no longer needed are lost due to the fact that the new bodily structure itself does not enhance the chance of survival in a particular environment (Kirchman 2009; Vieites, et al. 2009). In most cases these lost developments are passed down through future generations and are never redeveloped. However, more information is needed to decide whether or not the loss of these evolutionary developments was due to natural selection or by random mutation over years (Wilkens and Strecker 2003). In this paper, I will examine three studies from a diversity of taxa, which illustrate the history of flightless birds, how climate has influenced the evolution of salamanders and how life lived in darkness has influenced the blindness in cave fish. Together these studies depict how these evolutionary abilities are lost and their affects on the animal species.