Ratites are classified as a group of flightless birds, including ostriches, emus, cassowaries, and the now extinct elephant birds. Birds use flight as a way to escape predators, find mates, attain food, and migration, which raises the question, how did the ancestors of ratites re-locate from one landmass to another without the ability to fly? It was originally thought that there was a flightless common ancestor, but the closest relatives of the ratites are the flying South American Tinamous family. This suggest that the evolutionary distinction of being a large, flightless bird evolved in each isolated location influenced by environmental factors, mainly the lack of predators. Without the necessity to escape predation by flight, overtime ratites gradually loss the morphological structure of the keel that determined their mode of locomotion for their ancestors. Their response to improved environmental conditions promoted the success of each individual organism which contributed its genes to the succeeding generations. Many environments present challenges to a living species, to which the latter may respond by genetic adaptations (Dobzhansky 1973). Birds that are limited to the ground are more susceptible to predation, but these large birds have adapted to use their legs for reaching high speeds while running.
One major misconception about why ratites cannot fly is because they have a large body size when compared to other birds. Although the ability to fly decreases as body size increases in birds and other animals, the maximum mass-specific power obtainable from flight muscles can increase as body mass increases (Tobalske and Dial 2000). To study the effects of body size on flight in birds, four species were selected from within...
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... primitive tail designs of the Archaeopteryx evolved to that of modern birds. Understanding the mechanical use of the tail during flight can help scientists analyze the flight patterns, speed, acceleration, and landing of various birds.
Flight is the main means of locomotion for many species of birds. To understand how ratites evolved to losing their ability to fly, one must understand the evolution of flight. The changes in the environment allows a species to occupy the formerly empty ecologic niche as a new, improved opportunity for living (Dobzhansky 1973). Once the threat of predation disappeared, ratites were able to utilize the new ground niche to strengthen their ability to run, which provided an alternate way to escape predators. This study of evolution shows the importance of adaptations flightless birds have had to undergo to meet their needs of survival.
The four-pointed forkbird has the best suited evolutionary fitness. By the end of the activity, there were only two two-pointed forkbirds, one one-pointed forkbirds, and seventeen four-pointed forkbirds. This shows that four-pointed forkbirds have a better chance of surviving and passing on their traits.
Paul, Gregory S. (2002). "Looking for the True Bird Ancestor". Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Baltimore: Johns Hopkins University Press. pp. 171–224. ISBN 0-8018-6763-0.
The results from the experiments supported the hypothesis that the batoid pelvic girdle shape correlated with the type of locomotion. They found that the form of locomotion utilized by the batoid had a greater determining factor on the shape of the pelvic girdle compared to the phylogeny. An important discovery of this experiment showed that the shape of the pelvic girdle of a batoid can be used to predict the swimming and punting mode, and the order to which the vertebrate
Many people once believed that pterosaurs were weak flyers, or at least the larger ones were. The idea was that they used their large wings to glide instead of flap like flying creatures. This is now known to be false. Pterosaurs were also thought to be dinosaurs with similar anatomical features. Studies have shown now though that since the pterosaurs were not flappers but active flyers, their hearts were similar to those of mammals with four chambers, needed for an active way of life, unlike reptiles. In the past century, pterosaurs fossils have been known to be found with fur, which leads scientists to believe that pterosaurs needed insulation to keep in heat which indicated pterosaurs were active like mammals and warm blooded. 1
The second of Tinbergen’s questions Phylogeny looks at the evolutionary explanations of development, as opposed to just how behaviour has adapted, including mutations in response to environmental changes. Some of these mutations remain in species even after necessity has gone, and can influence future characteristics of that species. The third of Tinbergen’s questions looks at Causation,...
Both 1984 and The Handmaid’s Tale are dystopian novels, however, these books are a lot more complex than mere portrayals of dystopia, it can be argued that they are explorations of dystopia rather than mere portrayals. In order to explore dystopia, many themes must be considered, such as; feminism, love and repression. Nonetheless, it is apparent that human characteristics are the driving point of the two novels, predominantly, the depiction of human resilience. In an imperfect world, it is important to have certain qualities which, if plentiful, it can mean success, whereas if it lacks, it can mean failure, this characteristic is resilience. The protagonists in each novel, Winston in 1984 and Offred in The Handmaid’s Tale face situations which leave them both in disarray, and both even consider suicide. The authors tentatively highlight human resilience, its limits and most importantly its strengths into the two novels.
Hummingbirds have evolved certain behavioural and physical traits which allows for them to be more energetically efficient, such as specialized storage and digestion adaptations, feeding and flying adaptations and breathing adaptation. Hummingbirds are extremely small and their muscles for flight are highly oxygen-dependent and require large amounts of energy. Hummingbirds are one of the smallest endotherms and any energetic output can be metabolically stressful. The hummingbirds’ small body size means that they have very little room for energy storage and therefore often endure energetic and metabolic stresses. They are the one of the oldest aves, dating back to some 33 million years ago and have evolved certain energy efficient adaptations that have allowed for them to live so long. These adaptations allow Hummingbirds to efficiently meet their energetic needs which in turn, allows for them to not only survive but also continue to evolve and expand their specific niches.
The Hunger Games was a critically acclaimed movie when it came out; however, some critics would argue that the movie can be sometimes too violent for its intended audience. In this essay I would dissert Brian Bethune’s essay “Dystopia Now” in order to find its weaknesses and compare the movie Battle Royale with his essay.
“‘They score! Henderson has scored for Canada!’” Foster Hewitt wordlessly described” (Pelletier) when Paul Henderson scored the series-winning goal. This allowed Canada to win the 1972 Summit Series, a moment that no one would ever forget since it all happened during the climax of the Cold War. Prior to this, the Soviets had won the previous three Olympic gold metals since Canada could not use its NHL players. Thus, this provided Canada with the chance to play hockey against the USSR using its best players. This raised the question: if Canada were able to send its best players, would it still be enough to beat the Soviets? Everyone in Canada was certain that the Soviets would not win a single game, but little did they know they underestimated the extent of the Soviets abilities. Tied in the last few minutes of game eight, Canada had to score or they would lose the series. However, when Paul Henderson scored the game-winning goal, never before had a single sporting event meant so much to Canadians. Therefore, Paul Henderson’s goal is a defining moment for Canada in the twentieth century becauseit provided Canada with the opportunity to evolve hockey, proved that Canada and our democratic society were superior to the USSR and their communist society, and brought citizens together to unify Canada as a nation.
According to fossil records, Velociraptor stood at a height of only 2 feet and a length of 5 ½ feet (Glut, 1997). Velociraptor was roughly the size of a modern-day turkey, and the Velociraptor depicted in the film is closer in size to Deinonychus (Currie, 1997). In addition to the inaccurate size, paleontologists have discovered that Velociraptor possessed feathers. Quill knobs were found on the posterior forearm, which are identical in size and shape to the quill knobs found on present day birds that serve as anchor points for flight feathers (Turner, Makovicky, & Norell, 2007). The discovery of a new dinosaur with well-preserved feathers, Zhenyuanlong, which was a closely related cousin to Velociraptor presents strong evidence that it possessed feathers as well.
Marzluff, J., Angell, T. & Elliot, B. (2013, May. - Jun.). Birds: Brains over brawn. Audubon, 115(3), 40-41.
The results of natural selection in Darwin 's finches and British Columbian sparrows change my view of species because every living animal changes to survive conditions that get in the way of normal life.
Ratchet is the last one left from his kind, a reckless who grew up all alone without family on Planet Backwater. Clank is a tiny robot with low strength but high intelligence. These two heroes together are trying to save each planet in Solana Galaxy from a dreadful stranger named Chairman Drek. The movie revolves around the struggle of two dubious protagonists. They join hands with vibrant heroes called The Galactic Rangers in the edict
Nuddes and Dyke's analysis of the Archaeopteryx and Confuciusornis wing fossils concluded that their wings are too thin and weak to take flight ( 2010). According to Nuddes and Dyke, they would need to have solid primary feathers for them to be able to fly (2010). The fossils of the Archaeopteryx and Confusciusornis show rachises that are too narrow to fly. Also, their wings show the likelihood to fail by buckling if they attempt flight ( Nuddes and Dyke, 2010). Since the two species have similar wing feathers as the modern bird, the only way they could fly is if their wings serve as a parachute ( Nuddes and Dyke, 2010). In other words, they would have been gliders ( Nuddes and Dyke, 2010). Even with that theory, these birds are still weak flyers ( Nuddes and Dyke, 2010). Palaeontologist had found their fossils in lake sediments and oceans ( Nuddes and Dyke,
*The speed of migration is different for different species, depending on when they migrate. *A new study has found interesting differences in the migration speeds of early and late migrants between Europe and Africa. *In general, flight velocity of birds ranges from 20 to 50 miles per hour. *For sustained flight, larger birds typically fly faster than smaller birds. * A common flying speed of ducks and geese is between 40 and 50 miles per hour, but among the smaller birds it is much less. *Herons, hawks, Horned Larks, ravens, and shrikes, timed with an automobile speedometer have been found to fly 22 to 28 miles per hour, whereas some of the flycatchers fly at only 10 to 17 miles per hour. *Even such fast-flying birds as the Mourning Dove