The furcula is the main element of avian flight; it is an important origin for flight muscles used in the down stroke. Many biomechanical functions have been suggested for the Furcular. Originally it was thought to play a motionless function, acting as a spacer and muscle for flight. Other studies showed a more active role, where the furcular experience distortions during the wingbeat cycle, where it spread laterally on the down stroke and rebounding during the upstroke, almost acting like a spring. This behavior might represent an energy saving adaptation to help with respiration. Past studies have found that found that subaqueous fliers have more of a V- shaped furcular with a high anteroposterior curvature, whereas soaring bird are more U-shaped with low anteroposterior curvature. This study seeks to clarify this form-function relationship through the use of eigenshape morphometric analysis along with phylogenetic comparative methods (PCMs), and phylogenetic Flexible Discriminant Analysis (pFDA). Examination of flight modes revealed that intermittent bounders are associated with narrow interclavicular angles and straight clavicular rami. Short range fliers have a small anteroposterior curvature where larger …show more content…
Past studies showed the strength of the form and function relationship in the avian furcula, while this study examined the form and function in more modern Mesozoic birds. This study revealed that eigenshape analysis of Arvin birds furcular allows for more derived flight modes. This study confirmed that soaring birds have a more U-shaped furcula than continuously-flapping birds. It also observed that the interclavicular angle is an even more important aspect of flight mode than the curvature, and is positively correlated with body size. This study demonstrates that the Mesozoic taxa have evolved unique flight modes through different musculoskeletal
The Glen Rose Trackway is a 107-million-year–old series of fossilized dinosaur footprints. Excavated from the bed of the Paluxy River in Texas, the trackway gives a picture of dinosaurs that in some ways is more striking than that offered by fossils. Collected in 1938, the smaller prints are from a theropod, a dinosaur that walked on two hind feet. The larger ones were probably left by a plant-eating sauropod, such as Apatosaurus, the hind feet of which measured 3 feet in length. Birds are dinosaurs. Just as humans are both primates and mammals because we descended from the first primate and the first mammal, birds are dinosaurs because they descended from the first theropod and the first dinosaur. Their upright stance came from the very first dinosaur.
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.
Sean Carroll’s book Endless Forms Most Beautiful, attempts to explain the variety of animal forms, structures and functions by comparing them to rules that he had found. Such rules include: major “rules” for generating animal forms, species-specific encoding information, evolutionary diversity and large-scale trends in evolution. It begins by assessing the similarities between ancient and modern organisms. It notes that the structure of certain parts like vertebrates and limbs are similar in proportion and can be varied in shape and repetition. It cites animals parts like butterfly wings to show repetition of scales, snakes to show repeating vertebrae and compared a salamander to a dinosaur to express how each follow the same modular body plan.
Analogous Structures – structures that have the same function but different ancestry. (ex. – bird wing and bat wing)
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.
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
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
The author argues that the Pterosaurs were cold-blooded animals and they couldn't produce enough energy for flying by flapping. Conversely, the lecturer brings up the idea that the Pterosaur's body was covered by hair and this feature could efficiently isolate the heat in their body. This feature is common between warm-blood animals for saving energy. Therefore, these animals could have fast enough metabolic activity and efficient saving energy feature to produce and save energy for flight.
Observations: Our group dissected the left wing. Its top layer, the epidermis, was a light pink transparent color and it had a gelatinous texture . Through the epidermis, adipose tissue was visible, along with other connective tissues. The lower wing was small, thin, and pointy; while the upper wing was large, thick, and squishy. The alula was shorter and thicker than the wingtip, but the same shade of pink as most of the chicken wing. The wingtip was a darker shade of pink and it was longer, pointier, and thinner than the alula. There were
dinosaur found in this position is assumed to be warm-blooded, another similarity shared between birds and dinosaurs (Lemmonick 74 par. 1,7).
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.
A bird today can be defined as a creature with feathers and wings. The origin of flight in birds is as complex and slow as the evolution of birds themselves. To understand the origin of flight in birds we first need to discuss the origin of feathers. There are many theories of the origin of feathers but paleontologists and other scientists don’t have a clear answer to where it began. The earliest known fossils of feathers were the same fossils as mentioned above. Archaeopteryx, Sinosauropteryx, and many other theropod dinosaurs had feathers. Many scientists suggest that feathers were not the primary function of flight in birds. Prum and Brush (2002) suggests, “The model proposed a five stage transition series in the history of feather diversity as a hypothesized sequence of novelties in the feather development” (Prum & Brush, 2002). In short, the five stages suggests that the earliest feather was a simplistic tube and throughout time it gets more and more complex with aerodynamic properties. Theropod dinosaurs and other feathered dinosaurs likely