Transitional forms in existence today

Evolution also involves natural selection. It is a two step process where random mutation produces variation within the population and natural selection reduces the number of deleterious mutations while increasing the number of beneficial mutations. Your question can take on many meanings, so you may need to clarify exactly what you are looking for.Do you mean to ask why we don't see transitional features that carried over from past evolutionary events? If so, then your question is easily answered. Let's use mammals and reptiles as an example. From the fossil record we know that modern mammals evolved from ancient reptiles. This means that modern reptiles and modern mammals share a common ancestor. Both lineages branched off at this point, and each lineage continued to evolve. In the mammal lineage, many of the branches died off. However, there is one mammalian lineage where these transitional features have been preserved: the monotremes. The most famous species of monotreme is the platypus. In this species we see a very primitive lactation system, a body temperature much cooler than other mammals, and leathery eggs like those laid by modern reptiles. As you can imagine, not all transitional features are going to be preserved in a lineage over time.There are two things to keep in mind:1. All lineages evolve. Reptiles did not stop evolving after mammals branched off. The same goes for all of the mammalian lineages that branched off after they evolved from reptiles.2. Extinction happens. Lineages where transitional features can still be seen are at risk for extinction, as much as any other lineage. One of the reasons we do not see preserved transitional features is that those lineages went extinct.

peter1985,Languages are a good analogy to use when trying to understand how evolution works. As you may know, the Romance Languages are a language group that "evolved" from Latin. Here is an idealized lineage for the Romance languages: So you may ask why don't we hear anyone speaking a transitional language. If you went back 1,000 years you would be asking the same question even though those languages 1,000 years ago were the transitional langages between modern languages and vulgar latin. Also, the descendants of those who spoke proto-Italian, for example, are not speaking modern Italian.If humans evolved from a common ancestor with other apes why don't we see any transitional hominids today? For the same reason that no one speaks Middle English today.Edited by Taq, : No reason given.

What transitional mammalian features do penguins have?

Was your father fully formed, even though he was transitional between you and your grandfather? Was Middle English a fully formed language even though it was transitional between Old English and Modern English?I don't understand why you think that a transitional organism has to be less than fully formed.

Yes and no. It is a fact that fossils are transitionals. This is interpreted to mean that evolution occurred in the past. It is a fact that some fossils and modern species contain a mixture of features from two separate taxa. The platypus has both mammalian and reptilian features. For example, the platypus lays leathery eggs and uses a cloaca like a reptile. The platypus also has fur and mammary glands like mammals do. It is transitional by definition.Biologists use the fact of transitional fossils to conclude that evolution happened in the past. What you need to keep in mind is that the transitional nature of a fossil is not what is being interpreted. Rather, scientific theories such as evolution predict which transitional fossils one should see and not see.

Thank you for the correction, Captain Pedantry.

No one knows, just as no one in knew that Middle English was going to transform into Modern English. No matter what, we will be transitional between our ancestors and whatever those future humans evolve into.