Why the term “missing links” is inappropriate
Quite often we come across the term “Missing links ” while reading popular articles related to fossils in various news sites. The term Missing links is used to refer transitional forms.This term is mostly used in the popular media, but is always avoided in the scientific press as it is inaccurate and confusing. Majority of biologists are of the opinion that missing link is not appropriate term to use while referring to a transitional form not yet discovered in the fossil record.
Fossils are the remains of of animals, plants, and other organisms which existed long ago, giving us valuable clues to various life forms existed once on planet. Paleontology is the study of fossils across geological time, dealing with how they were formed and also their evolutionary relationships between taxa . A preserved specimen is called a â€œfossilâ€ if it is older than some minimum age, most often the arbitrary date of 10,000 years ago.
Fossils or organisms that show the transformation from an ancestral form to descendant species’ form is regarded as “Transitional form”. Archaeopteryx is a famous example of a transitional fossil which lived in late Jurassic Period around 155â€“150 million years ago.Archaeopteryx could grow to about 0.5 metres (1.6 ft) in length and Despite its small size, broad wings, and ability to fly(debated), Archaeopteryx share more common features with small theropod dinosaurs than it does with modern birds.There have been 9 specimens of Archaeopteryx found .
Why “Missing link” is an inappropriate term when referring to a transitional form ?
Few days back i received an article related to famous “Tiktaalik” through my e mail subscription and in that there was a small note about missing links. As it is very important to use correct terminology in subject, thought of sharing with all of you here.
“Missing” usually describes something that was supposed to be present but has disappeared for unknown reasons â€” if, for example, a favorite book suddenly disappeared from your room But you wouldn’t describe the book as “missing” if you had lent it to a friend and expected it to be gone.
The same holds true for the famous “Missing links”. Its quite well known fact that all former life will be preserved as fossils , in fact very few escape from vanishing without any trace. Fossilization depends on many aspects including nature of body form ( usually hard parts such as shells ,bones etc survive fossilization and soft bodies organisms are difficult to be found as fossils) and also environmental conditions in which the organism lives also matter a lot . So its believed that all intermediate steps during evolution ary transition (such as vertebrates’ invasion of the land) will not be preserved in the fossil record. But sometimes we do get lucky also and could see some transitional forms( eg: Tiktaalik ,archeopteryx) ,which are well preserved as fossils-but that does not mean that its ancestors, descendents, or other organisms that once lived on Earth are “missing.”
Read more on Transitional forms on my favorite evolution page
Transitional forms on Wikipedia
Image Credit : Wikimedia commons