Fossils provide direct physical information, such as skeletal structure and body size, on extinct species, as well as allow scientists to make inference on aspects of the species that cannot be preserved in the fossil records, such as their lifestyle and metabolism. The metabolism of Archaeornithes is often a subject of debate, as it could provide insight on the origin of endothermy in the Aves lineage. Many believe that Archaeornithes were endothermic due to their small body size, feather covering, and ability to perform metabolically demanding activities.
Members of Archaeornithes all had small body size as an adaptation for short flights, as exemplified by the Berlin fossil of the Archaeopteryx. With their small body size, they are more susceptible to heat loss as they have a larger surface area to volume ratio. Seebacher
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The cursorial hypothesis postulate that Archaeopteryx were likely fast ground runners and generated thrust for lift off by flapping their wings. The hypothesis is supported by calculations from an aerodynamic model, suggesting that Archaeopteryx could run at 6 metres per second before takeoff (Burgers & Chiappe, 1999). Their bone structure also support that they were fast bipedal ground runners, as Archaeopteryx had a larger hind limb to body proportion and slender limb joints that allowed them to bend their knees with ease (Lucas, 2007). Their fast, bipedal running speed, agility, and ability for flight suggest that Archaeornithes were endothermic, as these energetically demanding tasks would not be possible without the high basal metabolic activity of an endotherm. However, some believe that there is not sufficient information from the fossilized records to conclude that Archaeornithes were endothermic, as there are also other puzzling features that suggest them to be ectothermic, such as their avascular bone and lack of respiratory
Ceratopsians and Pachycephalosaurs are closely related in their characteristics. Ceratopsians processed a saddle-shaped boney frill that extended from the skull to the neck and typically had horns over the nose and eyes. The most popular was the triceratops, which could reach over 26 feet and weigh in excess of twelve metric tons. Their frills served as two major functions. It protected the vulnerable neck from being harmed. The second major function that the frill provided was due to the fact that the frill contained a network of blood vessels on its underside, which were used as a means to get rid of excess heat. The Pachycephalosaurs were considered to be bipedal. They were also found to have thick skulls, flattened bodies, and tail that were covered in an array of body rods. Pachycephalosaurs were thought to have been more than fifteen feet long and processed a skull that was surrounded by a rounded dome of solid bone. It was thought that they used their heads in combat or mating contests, but that was disproved fairly recently, which I will discuss later in the paper. Both Ceratopsians and Pachycephalosaurs were “bird-hipped” and both of these suborders contained a backwards pubic bone. Both were Marginocephilia, or “fringed heads”, which is one of three clads under the Orinthiscia order. They were also herbivore dinosaurs that inherited their fringe at the back of the skull from earlier ancestors.(2) Their classi...
Reptiles have a low metabolic rate: they consume energy, and therefore oxygen, slowly. According to Robinson (1975), Plesiosauroids were enduring swimmers with lower flipper aspect ratios and drag-causing long necks. Massare (1988) made the same conclusion, since the hydrodynamic properties of the Plesiosauroids indicate the species moved no faster than 2.3 metres every second. Therefore, the species was confronted by a conundrum: it sought to dive hundreds of metres to hunt its prey yet was constrained, by virtue of its body shape, to travel at slow speed. Invariably, the animal would have been required to forgo oxygen for periods of more than a minute, while keeping the presence of mind to hunt.
...s much of the time that some people have been led to believe. This belief had begun when they had discovered a fossil that has since been given the title “Selam”. “Selam” is the skull of a three year old female Australopithecus Afarensis who is believed to have been alive about 3.3 million years ago, having been discovered in the year 2000 in Ethiopia, Dikika by a paleoanthropologist named Dr. Zeresenay Alemseged. With Selam they have found that with the skeleton of her, that it shares many similarities when compared to the bone structure of an ape, meaning that the A. Afarensis may have lived a somewhat arboreal lifestyle. They at first checked the shoulder blades of “Selam”, with both remaining in fully intact which is considered to be very rare due the fact that the shoulder blades had remained intact through 3.3 million years, as it would allow them to find out
Metabolic rate is directly linked to the core temperature in an animal. An ectotherm, or cold blooded animal, warms its body mainly by absorbing heat from its surroundings. The amount of heat it derives from its metabolism is negligible. In contrast, endotherms derive most or all of its body heat from its own metabolism (Campbells,p899). Because ectotherms do not produce their own heat, they cannot actively ensure their ideal temperature for an ideal metabolic rate (aquacult.htp).
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.
Feder and Park present a list of traits that are used by paleoanthropologists to distinguish the appearance of skeletal features and characterize these changes over time. Th...
It also extends the process of learning about food chains and food webs. The first step in this lab is that the pellet was described as small, brownish-gray, round, furry, and soft. The second step the pellet was placed in the tray and carefully it was taken apart. Our fingers were used to rub together the fur of the owl that was then used to find the pH level of the owl. Distilled water was poured on the fur. Then pH paper was placed in the distilled water and then compared to find the pH level. The owl pellet was then taken apart carefully and the bones found were placed in a separate dish. A picture was then taken of the remains. The amount of remains was then recorded in the chart below. The materials that were obtained for this lab were one owl pellet, answer sheets, dishes and trays, forceps and probes, ruler, white paper, and an owl pellet bone
Australopithecus afarensis existed between 3.9 and 3.0 million years ago. The distinctive characteristics of A. afarensis were: a low forehead, a bony ridge over the eyes, a flat nose, no chin, more humanlike teeth, pelvis and leg bones resembled those of modern man. Females were smaller than males. Their sexual dimorphism was males:females; 1.5. A. afarensis was not as sexually dimorphic as gorillas, but more sexually dimorphic than humans or chimpanzees. A lot of scientists think that Australopithecus afarensis was partially adapted to climbing the trees, because the fingers and toe bones of the species were curved and longer than the ones of the modern human.
Bipedalism had many advantages, but it also had many disadvantages and provided dangers to early hominids. Some of these disadvantages included i...
They had shorter necks and much longer arms showing they used there front legs to gather food. there back legs were short but still strong to sit for long periods of time
The debate of whether dinosaurs were cold blooded or warm blooded has been ongoing since the beginning of the century. At the turn of the century scientists believed that dinosaurs had long limbs and were fairly slim, supporting the idea of a cold blooded reptile. Recently, however, the bone structure, number or predators to prey, and limb position have suggested a warm blooded species. In addition, the recent discovery of a fossilized dinosaur heart has supported the idea that dinosaurs were a warm blooded species. In this essay, I am going to give supporting evidence of dinosaurs being both warm and cold blooded. I will provide background information on the dinosaur that was discovered and what information it provides scientists.
Vestigial Structures are organs which are degenerated, atrophied, or in imperfect condition or form (Miller). These organs are important to showing evolution since they are useless limbs that at one point in our ancestry were useful for our daily functions. As stated by the article on livescience.com, the function of those vestigial organs eventually ceases to help the host and as such just stops working (Miller). Vestigial structures help us trace evolution because they show how species in the animal kingdom have changed over time. The appendix for example is present in vertebrate herbivores, so at one point the human ancestors probably had a very herb based diet (Miller). Another example is the hind legs on whales (Miller). They show that at one point, whales were land dwelling creatures, possibly amphibious, that decided to return to the sea life. The hind legs are completely useless to the present day whale, also the appendix to humans, but it shows that at one point in our timeline our ances...
The fossil record of horses extends back to an odd-toed ungulate mammal belonging to the taxonomic family Equidae, a dog-like ancestor 55 to 42 million years ago in the genus Hyracotherium in North America. Hyracotherium had a primitively little face , four-toed forefeet, three-toed hind feet, an arched back, small brain, and higher hindquarters than forehand. Later genus has increased in body size, brain complexity, the size of cheek teeth, lengthening of the face, and reduction of toe number. However, even though horses got larger over time but these trends are not seen in all of the horse lines. Genus such as Hipparion existed from 23 to 2 million years ago, showed gains in size, But some later genus such as Archeohippus, and Calippus got smaller again (Boundless, 2016),(Encyclopedia of Life,2015), (equineworld.co.uk, 2014), (Molen, M.
They had a big jaw with a U-shaped mouth with small teeth. The brain size of an Australopithicus is small and would reach approximately 340 to 500 cc, which is in the same range as gorillas and chimpanzees brain sizes. The top of their skull was a bony ridge. They were able to walk on their two feet and had a small pelvis. The Australopithecus were found with stone tools, which made them the first stone tool makers.
Homo erectus is also known for its larger body compared to earlier ancestors. "Past estimates of Homo erectus stature frequently were in the 5-5 1/2 feet (152-168 cm) range for adult males and arou...