Study Identifies Energy Efficiency As Reason For …
In the oceans, the Carboniferous is called the Golden Age of Sharks, and ray-finned fish arose to a ubiquity that they have yet to fully relinquish. Ray-finned fish probably prevailed because of their high energy efficiency. Their skeletons and scales were lighter than those of armored and lobe-finned fish, and their increasingly sophisticated and lightweight fins, their efficient tailfin method of propulsion, changes in their skulls, jaws, and new ways to use their lightweight and versatile equipment accompanied and probably led to the rise and subsequent success of ray-finned fish in the Carboniferous and afterward. , which are amoebic protists, rose to prominence for the first time in the Carboniferous. Reefs began to recover, although they did not recover to pre-Devonian conditions; those vast Devonian reefs have not been seen again. did not appear until the . Trilobites steadily declined and nautiloids familiar today, and straight shells became rare. The first , which were ancestral to squids and octopi, first appeared in the early Carboniferous, but some Devonian specimens might qualify. Ammonoids flourished once again, after barely surviving the Devonian Extinction. This essay is only focusing on certain prominent clades, and there are many and . The early Carboniferous, for example, is called the Golden Age of , which are a kind of , which is a phylum that includes starfish. The crinoids had their golden age when the fish that fed on them disappeared in the end-Devonian extinction. Earth’s ecosystems are vastly richer entities than this essay, or essay, can depict.
BIPEDALISM MODEL EVALUATOR : Home ..
In the mid-Miocene cooling’s early stages, beginning about 14 mya, apes were richly spread across Eurasia and were adapted to the hardier diets that less-tropical biomes could provide, and one from Spain 13 mya . It largely lived on the ground and had a relatively upright posture. Its discovery threw previously accepted ideas of ape evolution into disarray. The idea of apes ancestral to humanity living beyond Africa is a recent one, but is gaining acceptance. Important new fossils are found with regularity, as with all areas of paleontology, but the most plentiful funding is for investigating human ancestry. A , with features common to both orangutans and African apes, led to questioning whether some key ape features are ancestral or . One early finding is still highly controversial as to where it fits into the evolutionary tree, as it had ape and monkey features but lived 10 million years after the hypothesized ape/monkey split. The great ape lineages are the subject of considerable controversy today, and the human ancestral tree is regularly shaken up with new findings.
After the , when matter began to coalesce, virtually all mass in the universe was contained in hydrogen atoms, with traces of the next two lightest elements: helium and lithium. According to the , atoms have no mass by themselves, but the field that gives rise to the provides the mass. Gravity attracted hydrogen atoms to each other and, where “clumps” of hydrogen became large enough, the pressure in the clump’s center (a star’s core) became great enough so that the mutual repulsion of the protons in hydrogen nuclei was overcome (like charges repel each other, while opposite charges attract), and the protons fused together. That fusion released a great deal of primordial Big Bang energy, and fusion powers stars.
Why be bipedal? · john hawks weblog
Numerous causes for the evolution of human bipedalism involve freeing the hands for carrying and using tools, in provisoning, changes in climate and environment (from to ) that favored a more elevated eye-position, and to reduce the amount of skin exposed to the tropical sun. It is possible that bipedalism provided a variety of benefits to the hominin species, and scientists have suggested multiple reasons for evolution of human bipedalism. There also is not only question of why were the earliest hominins partially bipedal but also why did hominins become more bipedal over time. For example, the postural feeding hypothesis explains for how earliest hominins became for the benefit of reaching out for food in trees while the savanna-based theory describes how the late hominins that started to settle on the ground became increasingly bipedal.
Jan 06, 2018 · Why be bipedal
See main article: . According to the Savanna-based theory, descended from the trees and adapted to life on the savanna by walking erect on two feet. The theory suggests that early hominids were forced to adapt to bipedal locomotion on the open savanna after they left the trees. This theory is closely related to the knuckle-walking hypothesis, which states that human ancestors used quadrupedal locomotion on the savanna, as evidenced by morphological characteristics found in and forelimbs, and that it is less parsimonious to assume that knuckle walking developed twice in genera Pan and Gorilla instead of evolving it once as synapomorphy for Pan and Gorilla before losing it in Australopithecus. The evolution of an orthograde posture would have been very helpful on a savanna as it would allow the ability to look over tall grasses in order to watch out for predators, or terrestrially hunt and sneak up on prey. It was also suggested in P.E. Wheeler's "The evolution of bipedality and loss of functional body hair in hominids", that a possible advantage of bipedalism in the savanna was reducing the amount of surface area of the body exposed to the sun, helping regulate body temperature. In fact, ’s supports the savanna-based theory by explaining the shrinking of forested areas due to global warming and cooling, which forced animals out into the open grasslands and caused the need for hominids to acquire bipedality.