Amphibians as a Support for Evolution

I am always amused by Creationists’ denials that transitional forms exist among either fossil organisms or living species. After all, the definition of “transitional” depends on the existence and forms of two other organisms that the transitional form is being compared to. Thus Archeopteryx is called transitional because it has characteristics of both birds and theropod dinosaurs, which are reptiles. But if neither birds nor reptiles existed, then Archaeopteryx would not be transitional to anything.

It is the same with amphibians. Their very existence as a class is evidence of evolution, for they are clearly transitional between fishes (which are almost entirely confined to water, breath through gills, have fins instead of legs, and lay jelly-like eggs), and reptiles (which often have legs, can thrive even in dry deserts because they breath through lungs, and lay hard or leathery shelled eggs on land). Most amphibians as adults can live on land by walking on legs and breath air through lungs, but they lay eggs like those of fish and have a larval stage that lives in water and breaths through gills. So one could argue that a salamander is a modified fish or that a lizard is a modified salamander, thus regarding the salamander as a transitional form having characteristics of both.

One might also think a Creator of all living things from scratch would not bother to make animals with such lifestyles as amphibians. What would be the point, except to trick us into accepting evolution?

The forms of living amphibians also give us some insights into how evolution works:

  1. The Urodeles include the news and salamanders which have short and weak limbs, long bodies and tails, and a larval form that resembles the adult.
  2. Anuarans (frogs and toads) have very short bodies, powerful limbs, and no tails as adults, but have a very different larval form with a strong tail for swimming and no limbs. They are the most common amphibians.
  3. Gymnophiores, also known as caecilians, have no limbs at all and have extremely long bodies but little or no tail and live almost entirely underground. Indeed, they resemble giant earthworms.

It is easy to see how both frogs and caecilians could have evolved from salamanders by going in completely different directions. One might also suspect that salamanders are a transitional form between frogs and caecilians, but in fact the salamanders are the primitive forms most closely resembling the fish and lizards mentioned earlier, while the other amphibian forms resemble neither fish nor lizards, but are more specialized in their lifestyles.

Most fossil amphibians from the Devonian period to the Permian period have the form of salamanders, thus providing support for the hypothesis that salamanders are indeed the primitive form. In the mass extinction at the end of the Permian period, the giant amphibians that had been so common on the land disappeared. Later, one line of smaller amphibians developed into frogs in the Triassic period. Today, with so much competition from reptiles, birds and mammals, the smaller amphibians, numbering only 4,000 species, are a remnant of what the class once was.

A clueless pro-America zealot

In the Care2 group titled Hot Debates and Shocking News, which is one of the oldest and most respected groups in Care2, a member named Simon W posted a link to a story about supermodel Naomi Campbell visiting Venezuela, ruled by Hugo Chavez, to check out the reforms he has made under his socialist government. While I find some of Chavez’s actions towards his political opponents highly questionable, I found it commendable that someone in America, rather than just take her government’s propaganda at face value, would actually go to Venezuela to check out the facts for herself. But this did not seem to impress one bigoted observer.

Tony S: i didn’t respect her much before … i certainly respect her less now … reminds me of the old billy martin line … ” one’s a born liar, the other convicted”

Later, he said: well i’m sure simon put this post up because he is a fan of chavez … but to me chavez is an enemy to the u.s. and a tyrant in his own country. campbell’s visit to me and other celebs who have gone there, just make me sick. well pretty much most of hollywood makes me sick. but to me it reminds me of hanoi jane cuddling up with the enemy .. maybe not that bad, but close.  any visit gives him propaganda and a look of validation. and like i said … chavez is a born liar, campbell convicted… if these are hero’s to anyone that’s pretty sad.

So I answered him with one of my deadly “brief and to the point” replies.

Dale Husband: And you think Bush Jr is any better than Chavez, Tony S? If so, you are no less naive than Naomi Campbell.