Evidence for Endosymbiosis Abundant evidence has been found for endosymbiosis: Mitochondria and chloroplasts are similar in size and morphology to bacterial prokaryotic cells, though the mitochondria of some organisms are known to be morphologically variable. Mitochondria and chloroplasts divide by binary fission, just as bacteria do, and not by mitosis as eukaryotes do. Both types of organelle have Fts proteins at their division plane.
It is a trick question. You cannot do it. There is no convincing someone who has his mind made up already. But sometimes, it is even worse. Sometimes, when you point out a fossil that falls into the middle of a gap and is a superb morphological and chronological intermediate, you are met with the response: You are losing ground!
Duane Gish of the Institute for Creation Research ICR regularly trots out the "bossie-to-blowhole" transition to ridicule the idea that whales could have evolved from terrestrial, hooved ancestors.
There simply are no transitional forms in the fossil record between the marine mammals and their supposed land mammal ancestors. It is quite entertaining, starting with cows, pigs, or buffaloes, to attempt to visualize what the intermediates may have looked life.
Of course, for many years the fossil record for the whales was quite spotty, but now there are numerous transitional forms that illustrate the pathway of whale evolution. Recent discoveries of fossil whales provide the evidence that will convince an honest skeptic.
However, evolutionary biology predicts more than just the existence of fossil ancestors with certain characteristics - it also predicts that all other biological disciplines should also reveals patterns of similarity among whales, their ancestors, and other mammals correlated with evolutionary relatedness between groups.
It should be no surprise that this is what we find, and since the findings in one biological discipline, say biochemistry, is derived without reference to the findings in another, say comparative anatomy, scientists consider these different fields to provide independent evidence of the evolution of whales.
As expected, these independent lines of evidence all confirm the pattern of whale evolution that we would anticipate in the fossil record. To illustrate this approach, I will present the evidence from multiple fields for the origin of the whales from terrestrial mammals.
This paper will examine mutually reinforcing evidence from nine independent areas of research. Of course, as a starting point, we need to describe what makes a whale a whale.
What is a whale? A whale is first and foremost, a mammal - a warm-blooded vertebrate that uses its high metabolism to generate heat and regulate its internal temperature.
Female whales bear live young, which they nurse from mammary glands.
Although adult whales have no covering of body hair, they acquire body hair temporarily as fetuses, and some adult whales have sensory bristles around their mouths. These features are unequivocally mammalian.
But a whale is a very specialized mammal with many unique characters that are not shared with other mammals - many of these are not even shared with other marine mammals such as sirenians manatees and dugongs and pinnipeds seals, sea lions, and walruses. For example, whales have streamlined bodies that are thick and rounded, unlike the generally slim, elongated bodies of fishes.
The dorsal fin is stiffened by connective tissue, but is fleshy and entirely without supporting bones. The neck vertebrae of the whale are shortened and at least partly fused into a single bony mass.
The vertebrae behind the neck are numerous and very similar to one another; the bony processes that connect the vertebrae are greatly reduced, allowing the back to be very flexible and to produce powerful thrusts from the tail flukes.
The flippers that allow the whale to steer are composed of flattened and shortened arm bones, flat, disk-like wrist bones, and multiple elongated fingers. The elbow joint is virtually immobile, making the flipper rigid.
In the shoulder girdle, the shoulder blade is flattened, and there is no clavicle. A few species of whales still possess a vestigial pelvis, and some have greatly reduced and nonfunctional hindlimbs.A common evolutionary strategy to change the phenotype of a species is to change the developmental progression that leads to that phenotype.
This diagram is showing how bird evolution progressed to have the adult phenotypes look like the juvenile phenotype of the ancestral species.
The fossil record is indicative of evolution, but it is only one piece in the evidence puzzle. 3.
Embryology, similarity and vestigial structures. Understanding evolution: history, theory, evidence, and, Charles darwin was born in , seven years after his grandfather erasmus had died.
charles grew up during a conservative period in british and american society, shortly after the napoleonic wars. Human evolution is the evolutionary process that led to the emergence of anatomically modern humans, beginning with the evolutionary history of primates – in particular genus Homo – and leading to the emergence of Homo sapiens as a distinct species of the hominid family, the great monstermanfilm.com process involved the gradual development of traits such as human bipedalism and language, as well as.
Since Darwin first proposed his ideas about biological evolution and natural selection, different lines of research from many different branches of science have produced evidence supporting his belief that biological evolution occurs in part because of natural selection.
Linked from this page are documents summarizing the hominid fossil record and hypothesized lines of human evolution from 5 million years ago to the present.