In 1861 the first Archeopteryx was discovered. The feathers and other avian features combined with very specific dinosaur features put Archeopteryx right smack in the middle between modern birds and dinosaurs. In the years since it's position has remained between the two and a great deal of additional evidence linking dinos and birds has been discovered.
Recently Nature magazine published an article about some new discoveries including a fossil called Xiaotingia zhengi which shows that it is very closely related to Archeopteryx. In all honesty didn't evolution predict that there would be numerous steps connecting birds and dinosaurs? It also predicted that Archeopteryx exact position is still unknown, that it might be a directly in the hierarchy or possibly a side branch that eventually went extinct. Well Xiaotingia zhengi appears to have pushed Archeopteryx closer to the dinosaurs, including velociraptor, the 'star' of Jurassic Park. In fact the abstract from Nature says
"Despite only tentative statistical support, this result challenges the centrality of Archaeopteryx in the transition to birds. If this new phylogenetic hypothesis can be confirmed by further investigation, current assumptions regarding the avialan ancestral condition will need to be re-evaluated."As I read this I saw a perfect example of science in action. We explain based on current knowledge. New discoveries mean new knowledge and an adjustment to current explanations. This is one of the strengths of science!
But, as we know, the folks at Uncommon Descent aren't very scientific, because they are claiming that the whole Bird to Dinosaur idea is a bad idea and needs to wait until there is further research. "David Tyler on rewriting the textbooks on Archaeopteryx – that dinobird, no longer First Bird, downgraded to dinosaur" is the post, you can link to Tyler's article from there if you wish. It includes this as part of his summary:
"Creataceous fossil record shows many features that we do not properly understand, and the most appropriate response is to withhold judgment and await further discoveries and analysis. This applies to the whole of the Birds Are Dinosaurs (BAD) thesis . . ."So in other words until we have absolutely perfect understanding and 100% perfect data we should just sit on all discoveries. That's crap!
What drives new discoveries? The work of the past. The work we are doing right now will be the impetus to some future archaeologist and paleontologist to take the next step. Tyler is trying to make the scientific process a disadvantage. In reality wherever Archeopteryx ends up in the hierarchy, or if we can someday confirm it as an evolutionary dead-end is immaterial. Yes, as we learn new things we will be adding to textbooks and changing what is in the current texts. I'm pretty sure the medical text of today are quite a bit different than the ones from 1861, why is this suddenly a bad thing?
What we know today will be different than what we know in the future . . . but that in no way invalidates what we know right now! Archeopteryx was positioned based on what we knew. We also know that the evidence that supported that was not static, but subject to new discoveries -- and we readily published that -- so what! We went to the moon with a less than perfect understanding of Gravity, we build cars with a less than perfect knowledge of thermodynamics, we create new medicines and new medical techniques with a less than perfect knowledge of biology. We can only use what we know right now. If we do what Tyler wants we should have never left the cave!