We've all heard of the fossil Archaeopteryx - it's a fabled Icon of Evolution, a strong point for all those who wish to find a transition fossil for those pesky doubters that just won't keep quiet. After all, this fossil has feathers (obviously a bird trait), teeth (reptilian - I mean, who's ever seen a toothed bird?), a long tail (definitely lizard), a furcula ("wishbone", a feature of birds) and three claws on each wing. Much has been made of this apparent hodge-podge of features, and Archaeopteryx has been firmly placed in evolutionary phylogeny as one of the earliest forerunners of the modern bird.
This lovely looking bird is extant in the Amazon rain forest and the Orinoco delta of South America. It inhabits swamps and is a strict herbivore, fermenting the greens it eats in it's belly much like more popular bovines (no relation). The pungent odor emanating from the digesting food in it's crop gives rise to it's second, more colloquial, name - the stinkbird. One other interesting feature of this bird is that newly hatched chicks actually have claws on their wings when young, although the claws shrink away and even disappear as the bird grows older. Other examples of clawed birds include the entire order of Anseriformes, which has two spikes on their carpometacarpus (wrist), and the species Plectopterus gambensis, more commonly known as the spur-winged goose, which has a sharp spike on it's wings that is an extension of the radiale. So, birds having spikes on their wing-tips are not quite as rare as they would seem to be. And regarding birds with teeth; as odd as it may sound, some birds today do have teeth, or at least have calciferous serrations running along their mandibles. The Graylag Goose comes to mind, as does the Tooth-Billed Bowerbird - both of which are still living today.
So, the Archaeopteryx may not have been that remarkable after all. In fact, there is a theory postulating that the Bible does mention the Archaeopteryx, and even billed it as unfit to eat in Leviticus! I know that I've promised to stick to science on this blog, but I just have to mention this. If, however, you are not a Christian and don't believe the Bible is the Word of God, feel free to skip, ignore, and even deride the rest of this paragraph. In Leviticus 11:18, when the Israelites are being given the list of animals not to be consumed, the "white owl" is mentioned as unfit for consumption - the word used was "tanshemeth". However, in Leviticus 11:30, a few verses later, the same word "tanshemeth" reappears, this time used as a "chameleon"! This dichotomy can be explained by a fringe hypothesis that postulate that perhaps the Bible was referring to a creature that appeared to be a cross of reptiles and birds - the Archaeopteryx! Of course, there are other interpretations and explanations, but I felt that I should at least mention this for any Christians out there. Comment any questions, and I'll get back to you.
Sources
http://www.ucmp.berkeley.edu/diapsids/birds/archaeopteryx.html
http://en.wikipedia.org/wiki/Platypus
http://scienceblogs.com/tetrapodzoology/2010/06/30/clubs-spurs-spikes-and-claws/
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| Early image of what Archaeopteryx looked like. Later images have a less reptilian head, in keeping with recent findings |
However, it's unclear whether merely sharing the characteristics of two major phyla is enough to prove that any creature is not an individual species of it's own. What do I mean by this statement? Well, take a look at the platypus - my favorite marsupial around. It has webbed feet (amphibian?), a rubbery beak (bird?), venomous ankle spurs (reptile?), lays eggs (bird?), and is...a mammal! Wow! The point of this apparently pointless list was to highlight something I believe is ignored too often - just because a creature shares the characteristics of other creatures from different phyla, said creature does not has to be a mix between them, or even related to them! The platypus has never been called a missing link, and yet I feel that if it had been extinct, it's fossils, much like the coelacanth's, would have been heralded as intermediate forms. On the flip side, this is not an apt comparison, as the Archaeopteryx's features are completely unique - no living bird has claws on it's wing's, no? And no bird has teeth - so Archaeopteryx is unique in an entirely different way, right? Cue the hoatzin.
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| The hoatzin - a flashy looker |
This lovely looking bird is extant in the Amazon rain forest and the Orinoco delta of South America. It inhabits swamps and is a strict herbivore, fermenting the greens it eats in it's belly much like more popular bovines (no relation). The pungent odor emanating from the digesting food in it's crop gives rise to it's second, more colloquial, name - the stinkbird. One other interesting feature of this bird is that newly hatched chicks actually have claws on their wings when young, although the claws shrink away and even disappear as the bird grows older. Other examples of clawed birds include the entire order of Anseriformes, which has two spikes on their carpometacarpus (wrist), and the species Plectopterus gambensis, more commonly known as the spur-winged goose, which has a sharp spike on it's wings that is an extension of the radiale. So, birds having spikes on their wing-tips are not quite as rare as they would seem to be. And regarding birds with teeth; as odd as it may sound, some birds today do have teeth, or at least have calciferous serrations running along their mandibles. The Graylag Goose comes to mind, as does the Tooth-Billed Bowerbird - both of which are still living today.
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| The glorious Graylag Goose, complete with grin |
So, the Archaeopteryx may not have been that remarkable after all. In fact, there is a theory postulating that the Bible does mention the Archaeopteryx, and even billed it as unfit to eat in Leviticus! I know that I've promised to stick to science on this blog, but I just have to mention this. If, however, you are not a Christian and don't believe the Bible is the Word of God, feel free to skip, ignore, and even deride the rest of this paragraph. In Leviticus 11:18, when the Israelites are being given the list of animals not to be consumed, the "white owl" is mentioned as unfit for consumption - the word used was "tanshemeth". However, in Leviticus 11:30, a few verses later, the same word "tanshemeth" reappears, this time used as a "chameleon"! This dichotomy can be explained by a fringe hypothesis that postulate that perhaps the Bible was referring to a creature that appeared to be a cross of reptiles and birds - the Archaeopteryx! Of course, there are other interpretations and explanations, but I felt that I should at least mention this for any Christians out there. Comment any questions, and I'll get back to you.
Sources
http://www.ucmp.berkeley.edu/diapsids/birds/archaeopteryx.html
http://en.wikipedia.org/wiki/Platypus
http://scienceblogs.com/tetrapodzoology/2010/06/30/clubs-spurs-spikes-and-claws/
