The disagreements in the scientific community are often played up by the anti-science crowds in their effort to make a case for their own views. In terms of concord, suggest the intelligent design crowd, anything less than 100% agreement - even agreement anywhere in the ninety percent or higher range - is apparently just cause for everyone to down tools and take the view that it must have been a designer after all. Mechanisms of nature which are predictive and shown repeatedly to be the driving force in the gradual changes in species over millions of years are insufficient in the light of this "all or nothing" approach. Mind you, they still won't tell us who the designer is, but with the number of biblical quotations that lace their books (at least, in the West, Adnan Oktar aside), we can probably take an ultimately accurate wild stab in the dark as to their number one candidate.

Take, for example, the suggestion that bird evolution can be linked directly to survivors of the therapod dinosaur lineage (seemingly earlier off-shoots of the therapod line). Therapods were the two-legged, feathered dinosaurs, of which some famous exemplars - archaeopteryx, sinoraptor, and recent Chinese fossil discoveries, among others - seem to point conclusively toward evolution and adaptation from the saurian to the avian.
I've met at least one paleontologist who is one of the opposing camp, a group which suggests that this business of the evolution of birds from dinosaurs is, in fact, completely ridiculous. Among others who do not accept the direct therapod connection are paleontologists like
Larry Martin of the University of Kansas, for one, who is among a number of highly respected experts who have found the evidence to be unconvincing. They appear to be in a dwindling minority within the paleontological community, though, especially in the light of the growing number of fossils discovered in China which appear to point to a direct therapod-to-avian connection. Unfortunately, that doesn't stop their disagreement from being seized upon by "cdesign proponentists", who are apparently above doing research of their own, instead using a legitimate conflict of scientific opinion as the hammer-to-nail seal in the coffin of evolutionary theory (short answer: no, it isn't).
The discovery of a new therapod in Argentinia opens up the debate yet again, as recorded in a recent story from the
National Geographic (and other news sources). Argentinia has been a rich source for fossils since before Darwin's time, and has now yielded
Aerosteon riocoloradensis, which is shaking the tree once more. One of the most interesting claims about this new fossil is that it breathed in the same way as modern birds. No doubt, this will be a source of controversy.

How do we know how dinosaurs breathed? How do we understand what their lungs must have been like, when lungs don't fossilise? This is a function of comparative anatomy, a field pioneered by one of the true geniuses of the 19th century,
Georges Cuvier (1769-1832). Cuvier, a member of the French Academy of Sciences and a director of the Muséum National de l'Histoire naturelle (
Wiki |
Official Site), pioneered the comparison and identification of animals by their physical characteristics, a field which forms the basis of the discipline of comparative anatomy. It was Cuvier who determined that certain fossils, including a variety of extinct
elephant lineages and the Paraguayan
megatherium were not from known examples of otherwise unknown living species, which in part led to the first realisation that several major faunal groups were represented in the primitive fossil record that were not known in the modern world.

We can tell a great deal from bones, as the much vaunted techniques of crime scene investigation, in all its televisual glory, tell us. The shape of bones can lead to the reconstruction of a face or any other body part supported by bone, because we know how the shape of the bones dictates the distribution of tissue in different species. Broken or damaged bones tell us about lifestyle. The bones themselves can be different - bird bones, as is well known, are hollow, giving our avian friends the ability to fly. And, when faced with an unknown bone, we can rebuild with a fair degree of accuracy a representation of what the living creature must have looked like. This was the field pioneered by Cuvier, and it is said that he could look at a single bone and reconstruct an accurate picture of the animal from which it came. Probably an exaggeration, but there is no doubt of his skill and expertise.
Cuvier attributed the similarities that he observed between species, and the clear distinctions from other species, to the concept of the
Great Chain of Being, or
scala naturae, a theoretical framework still popular in the 18th century which proposed a natural hierarchy of all of the creatures in the world (and the gods and sprites outside of it). It is from the
scala naturae concept that we still retain the conception of the lion as the "King of Beasts", and the oak as the "sovereign of trees". The
scala naturae also gave rise to the idea of the divine right of kings, which as a part of modern theology is curiously lacking in the schema of beliefs propounded by creationists, especially American ones. But back to Cuvier, in the face of the similarities between related and unrelated animals species which he observed, he couldn't accept the idea of the transformation of species, even as tentatively put forward by the Comte de Buffon. According to John C. Greene, author of
The Death of Adam: Evolution and Its Impact on Western Thought
, "Cuvier was attempting the impossible task of reconciling two conflicting views of nature" (p. 173
ff). Greene continues: "That Cuvier was able to make these views seem compatible testified both to the greatness of his prestige and to the strength of the contemporary demand that the new science be reconciled with the traditional view of nature." It would take a mind like that of Charles Darwin, and another fifty years, to wrest all of the conflicting threads of 18th and 19th Century thought into place, and to show the incompatibility for what it was.
When you look at the chest cavity of an 80 million year old dinosaur, comparisons with modern reptiles and birds which are similarly structured provide us with an excellent idea of the arrangement and function of the internal organs (that is part of the evidence from the new find cited in the National Geographic article). In the light of evolution in a Darwinian mode, we are presented with an explanation for this: earlier forms gave rise to later, through natural selection and descent with modification. It's first-year Evolutionary Biology, in essence. Sometimes, as Cuvier said two hundred years ago, and well before Darwin, the process throws up dead ends, and sometimes not. Cuvier says (quoted in Greene):
"Nature never oversteps the bounds which the necessary conditions of existence prescribe to her; but whenever she is unconfined by these conditions she displays all her fertility and variety. Never departing from the small number of combinations that are possible, between the essential modification of important organs, she seems to sport with infinite caprice in all the accessory parts. It even frequently happens, that particular forms and dispositions are created without any apparent view to utility. It seems sufficient that they should be possible, that is to say, that they do not destroy the harmony of the whole."
-- Georges Cuvier, Lectures I, p 58-9
Despite getting this much of the puzzle, Cuvier, didn't see the whole. In that way, he is much like the unscientific "cdesign proponentists", who I like to think he would have reviled. But it seems as though he had made it part of the way along the road, and given slightly greater knowledge, Cuvier too would have been convinced by descent with modification via natural selection. And he would have been delighted to know that the field which he pioneered had yielded so many fruitful results, that even to this day human beings were unearthing more and more of the story of life's past on Earth.
At the end of the day, it doesn't seem that the idea of a scala natura was as far wrong as we might once have thought. It was, in a sense, right. But it was right for entirely the wrong reasons. Rather than a divine hand forging links in a chain, it has always been selection of random mutation building on accreted adaptations over a huge span of time. And that is the sort of theoretical achievement, whether illustrated by birds descended from dinosaurs or from the diversity of the proboscidae, of which "cdesign proponentists" could only dream.
There is always more to learn. And learning must come from doing. The more that we do, the more we study, the more we search for new things that we have never seen before, the more we will learn. And as human endeavour goes, that's certainly the most worthwhile way to spend your days that I can think of.
EDIT: Several edits for clarity in the above, proving once again that I shouldn't rush my drafting process. Apologies for the annoyance of having to read for revisions.