Tuesday, September 27, 2011

* The Missing SERIES

By the way, it is not just ONE hypothetical most recent common ancestor that is missing in the dino to bird purported lineage - it is a whole series of them along the purported lineage line. Cladistics has not discovered or described ANY of them!

Luckily there are other more common-sense approaches to establishing phylogeny, that includes the effort to determine ancestors and descendants.

Sunday, September 25, 2011

Cladistics - a missing link that is always missing

"Also, unlike Cladistics, with it's reliance on a hypothetical Most Recent Common Ancestor that is never actually described or discovered (a missing link that is always missing), Evolutionary systematics gives illustrations of the actual evolution of one species or higher taxon into another."

I am certainly not the only one who has seen the problems with cladistics .

Friday, September 23, 2011

* Dino to bird problem

Here is something noteworthy concerning the dino (non-maniraptor coelurosaur) to bird idea:
There are fossils for a number of taxa in the fossil record. But none of those work out as ancestors. 
Thus it strains credulity that the dino to bird enthusiasts fall back on the story that there is a lack of fossils. 

That is the dino to bird problem.

But as folks must know by now, my main interest is in presenting the case for  pterosaurs as the ancestors of birds, not hashing and re-hashing the problems with the dino to bird idea. .

*Note again that by "dino" I mean non-maniraptor coelurosaurs. They are not ancestral to birds.

Wednesday, September 21, 2011

Jackie Evancho

To take a break from pterosaurs, I want to bring to your attention Jackie Evancho (if you are not already familiar with this angel).



We cannot understand the total of reality with just our intellect and senses. We need the inspiration and insight of emotion. Then we see more deeply.

Tuesday, September 20, 2011

The significance of the Senter studies

It may be that Senter still does not realize what he has done inadvertently.
He set out to make fun of "creationists" but he has highlighted the Achilles heel of the dino to bird theory.
Generally, articles on the dino to bird theory focus on how maniraptors are birds. And because the writers call maniraptors "dinosaurs", readers are left with the impression that birds evolved from dinosaurs.
But using baraminology, Senter brings to light the separation between dinosaurs (non-maniraptor coelurosaurs) and maniraptors. He calls them the "tyrannosaur cluster" and the "bird-like cluster".
No evidence has EVER been produced for a connection between dinosaurs (non-maniraptor coelurosaurs) and manirpators.
And now Senter documents that they are not connected.
It is too late for Senter to now deny what his data and analysis have shown.

Thursday, September 15, 2011

Which one of these is not like the others?

Which one of these is not like the others? Actually there are two, if you look carefully.

Notice also the size depicted for the bird in the top right. It is as big as a tyrannosaurus. This chart is wrong in so many ways.

Wednesday, September 7, 2011

Pterosaur Bird Correspondences (2)

The Jablonski article is not itself on the topic of pterosaurs to birds. But there are a few points of interest:
1. Jablonski has noted the similarities between specific pterosaurs and specific categories of modern birds. That is something I had noted as well.
2. Jablonski says that pterosaurs "vacated".
In line with what I am saying, the pterosaurs developed into primitive birds -  either through anagenesis or cladogenesis followed by extinction of the pterosaurs.
3. It is worth noting that primitive pterosaurs (Rhamphorhynchus) developed into the advanced pterosaurs (Pterodactylus) presumably in the same way.

Tuesday, September 6, 2011

Pterosaur Bird Correspondences (1)


"Over the course of Cenozoic diversification,
other birds did assume modes of life similar to those
vacated by pterosaurs: skimmers may roughly correspond to
Tropeognathus with its keeled jaws, swallows and swifts to
Pterodactylus with its similar size and wing proportions, flamingos
to Pterodaustro with its bristling array of fringe-like teeth, and
perhaps even condors to the enormous Quetzlcoatlus".

More on Facilitated Variation and Wing Development

Adaptable robust processes can support nonlethal phenotypic variation in other processes, a situation called “accommodation” by West-Eberhard (14). A specific example is the evolution of the tetrapod  [pterosaur] forelimb to a bird or bat wing. Not only did the length and thickness of bones change, but also the associated musculature, nerve connections, and vasculature. Did many regulatory changes occur in parallel, coordinated by selection, to achieve the coevolution of all these tissues in the limb evolving to a wing? The answer comes from studies of limb development showing that muscle, nerve, and vascular founder cells originate in the embryonic trunk and migrate into the developing limb bud, which initially contains only bone and dermis precursors. Muscle precursors are adaptable; they receive signals from developing dermis and bone (17) and take positions relative to them, wherever they are. Then, as noted previously, axons in large numbers extend into the bud from the nerve cord; some fortuitously contact muscle targets and are stabilized, and the rest shrink back. Finally, vascular progenitors enter. Wherever limb cells are hypoxic, they secrete signals that trigger nearby blood vessels to grow into their vicinity (18). 

Monday, September 5, 2011

Pterosaur Wing to Bird Wing

The development of the pterosaur wing to the bird wing requires fewer changes than one might think due to "facilitated variation".

"The adaptability and robustness of normal muscle, nerve, and vascular development have significant implications for evolution, for these processes accommodate to evolutionary change as well. In the case of the evolving wing, if bones undergo regulatory change (driven by genetic change) in length and thickness, the muscles, nerves and vasculature will accommodate to those changes without requiring independent regulatory change. Coevolution is avoided. Selection does not have to coordinate multiple independently varying parts. Hence, less genetic change is needed, lethality is reduced, larger phenotypic changes are viable, and phenotypic variation is facilitated.(John Gerhart and Marc Kirschner 2007)