Overview of basic ideas

Note that I am just focussing now on the idea that basal pterosaurs evolved into basal Paraves and not on the following: 

The pterosaur to bird theory contains two basic ideas, that differ from current mainstream thinking.
The first idea is that pterosaurs developed into a set of primitive bird lines.
The second is that EACH ONE of those primitive bird lines then developed into a set of corresponding modern birds, in what might be called a set of "parallel lines".

For example:
Seabirds (Ichthyornithes line)

• Pterosaur (Ornithocheiroidea) eg. Pteranodon --> 
• An Ichthyornithes subgroup --> 
• Gulls, Skimmers (Charadriiformes/Lari)

Here we see one of the parallel lines of primitive birds (Ichthyornithes), developing into the set of corresponding modern birds.

If any of this is not clear, I invite questions and comments.

Note: Most of the posts on this site present evidence supporting the pterosaur to bird theory. Some of the posts show the flaws in the current, mainstream dinosaur to bird theory. I have put an asterisk (*) at the beginning of the post titles that are on the flaws of the dinosaur to bird theory.

Categories (Updated)

See the updated version posted on Jan 15, 2013.

For ease of reference, here is the list of links to the updated categories I have analyzed to this point. This is a work in progress.

Categories:

See the updated version posted on Jan 15, 2013.

For reference:

http://en.wikipedia.org/wiki/Pterosaur

As a result, the possibly fish-eating Ctenochasma and Rhamphorhynchus may have had similar activity patterns to modern nocturnal seabirds, and the filter-feeding Pterodaustro may have had similar activity patterns to modern anseriform birds that feed at night. 

Some [pterosaur] advanced beaked forms were toothless, such as the pteranodonts and azhdarchids, and had larger, more extensive, and more bird-like beaks.^[25]

http://en.wikipedia.org/wiki/Rhamphorhynchoidea
210–124.5 Ma

http://en.wikipedia.org/wiki/Pterodactyloidea

• Azhdarchoidea 148.5–65.5 Ma
• Ctenochasmatoidea 166–124.6 Ma
• Dsungaripteroidea 155–112 Ma
• Ornithocheiroidea (eg Pteranodon) (130–70 Ma)

http://en.wikipedia.org/wiki/Modern_birds

Cladogram showing the most recent classification of Neoaves, based on several phylogenetic studies.

Not yet categorized:

• Pelican
• Vulture
• Condor

Pterosaur brachiopatagium to bird postpatagium

Lets look at the brachiopatagium of the pterosaur and see how it changed in the development to bird.

http://books.google.ca/books?id=nQ3vLQkEWQMC&pg=PA56&lpg=PA56&dq=postpatagium&source=bl&ots=F45R6-nU20&sig=wAVGEOUZ5wVoLpwKjqQyaQJ0c_g&hl=en&sa=X&ei=69HIUMCDFvDlyAGSy4H4BA&ved=0CDkQ6AEwAQ#v=onepage&q=postpatagium&f=false

"Several sheets of tough, tendinous tissue form significant parts of the wing structure: the patagium and the patagialis longus muscle and tendon actually form much of the leading edge of the wing"

Note page 128 of this reference:
http://books.google.ca/books?id=KG86AgWwFEUC&pg=PA128&lpg=PA128&dq=bird+postpatagium&source=bl&ots=RtK3TnXIZI&sig=1E_t2KtzJvsO5J1risrR6Ujv52I&hl=en&sa=X&ei=gGvcUsuOGqTu2AW-xYD4BQ&ved=0CFwQ6AEwBA#v=onepage&q=bird%20postpatagium&f=false

^{http://www.wordnik.com/words/postpatagium}

Postpatagium:
^{n. In ornithology, the triangular fold of skin, just back of the shoulder-joint, which runs from the side of the body to the upper posterior face of the upper arm.}

It may well be the case that the development from the pterosaur  brachiopatagium  to the primitive bird wing skin took place in one step through a mechanism such as "facilitated variation".

Also Scansoriopterygidae presents as an excellent transitional wing skin membrane, between pterosaur and later members of Paraves.

See the following references for more info on the fascinating topic of facilitated variation:
http://pterosaurnet.blogspot.com/2011/09/pterosaur-wing-to-bird-wing.html
http://pterosaurnet.blogspot.com/2011/09/more-on-facilitated-variation-and-wing.html
http://en.wikipedia.org/wiki/Facilitated_variation
http://www.pnas.org/content/104/suppl.1/8582.full

* No antecedent structures in dino to bird theory

http://prumlab.yale.edu/sites/default/files/prum_n_brush_2002.pdf

Feathers, however, are hierarchically
complex assemblages of numerous
evolutionary novelties—the feather follicle,
tubular feather germ, feather branched structure,
interacting differentiated barbules—that
have no homolog in any antecedent [dinosaur] structures
(Brush 1993, 1996, 2000; Prum 1999). Genuine
evolutionary novelties are distinct from
simple microevolutionary changes in that they
are qualitatively or categorically different from
any antecedent or homonomous structure.

"In conclusion, the morphological and
molecular developmental details shared by
avian feather and scales support homology
between these structures at the level of the
placode. The morphology and development
of all subsequent structures within the feather
are evolutionary novelties that have no homologs
in avian or reptilian scales.

 "Many features of feathers and feather development meet this definition and qualify as evolutionary novelties. The follicle, the differentiated sheath and feather germ, differentiated barb ridges, barb rami, barbules, differentiated pennulae of the proximal and distal bar bules, and the rachis are all evolutionary novelties, as are the derived mechanisms by which these novel structures develop. At a molecular level, the derived 10 kilodalton -keratins of feathers are also novel"

In regards to the feather, the dino to bird theory (according to Prum and Brush) depends on a series of miracles (aka "numerous evolutionary novelties that have no homolog in any antecedent structures").
The pterosaur to bird theory is not based on miracles.

* Dinosaurs did not have wing-like arms

I could hardly have put it better than the following:
http://scienceblogs.com/tetrapodzool..._they_dont.php

Quote:

The fact that long remiges have now been documented in oviraptorosaurs, dromaeosaurids and other maniraptorans shows that feathered arms essentially the same as those present in basal birds evolved somewhere round about the base of the oviraptorosaur + paravian clade, and there is no evidence that wing-like arms were present in more basal coelurosaurs, nor in other theropods, or other dinosaurs, or other archosaurs.

The dino to bird folks do not specify their imagined lineage. But they have some belief that coelurosaur dinosaurs evolved into Paraves and those Paraves evolved into modern birds. But it leaves open when in that lineage "wing-like arms" appeared.
Naish asserts that "feathered arms essentially the same as those present in basal birds evolved somewhere round about the base of the oviraptorosaur + paravian clade".
He then says that "there is no evidence that wing-like arms were present in more basal coelurosaurs, nor in other theropods, or other dinosaurs, or other archosaurs."
In other words, concerning wing arms, there is no connection whatsoever between dinos and paraves/oviraptors.

http://www.ivpp.cas.cn/qt/papers/201403/P020140314389417822583.pdf

Page 9/10
The relative length and diameter of the humerus in several theropod taxa. We use
the ratios of humeral length to femoral length, and humeral diameter to femoral diameter, as
indicators of forelimb length and robustness. Relative to the femur, the humerus is
significantly longer and thicker in basal paravians than in non-paravian theropods, derived
dromaeosaurids and troodontids (the relatively short and slender forelimbs in the last two
groups are secondarily evolved according to the current phylogenetic analysis).
Page 28/29
The discovery of Xiaotingia further demonstrates that many features
previously regarded as distinctively avialan actually characterize the
more inclusive Paraves. For example, proportionally long and robust
forelimbs are optimized in our analysis as a primitive character state
for the Paraves (see Supplementary Information). The significant
lengthening and thickening of the forelimbs indicates a dramatic shift
in forelimb function at the base of the Paraves, which might be related
to the appearance of a degree of aerodynamic capability. This hypothesis
is consistent with the presence of flight feathers with asymmetrical
vanes in both basal avialans and basal deinonychosaurs6,23

* Hypothetical Creatures

http://scienceblogs.com/tetrapodzoology/2009/06/birds_come_first_no_they_dont.php

But, ultimately, BCF is entirely unsatisfactory: we're supposed to construct scientific hypotheses based on the evidence we have, rather than on the evidence we think there should be, and BCF is just way too speculative. It proposes the existence of a whole lineage of hypothetical creatures that are absent from the fossil record.

Naish makes it sound like there is a problem if you propose the existence of a whole lineage of hypothetical creatures that are absent from the fossil record.

But of course that is EXACTLY what the dino to bird theory does!
As I have pointed out again and again.

* Paraves to modern bird

http://onlinelibrary.wiley.com/doi/10.1111/j.1420-9101.2012.02465.x/abstract;jsessionid=D85984F3042F8E00C550060394176368.d03t02?systemMessage=Wiley+Online+Library+will+be+disrupted+4+Feb+from+10-12+GMT+for+monthly+maintenance

"Shared behavioural, morphological and physiological characteristics are indicative of the evolution of extant birds from nonavian maniraptoran dinosaurs. One such shared character is the presence of uncinate processes and respiratory structures in extant birds. Recent research has suggested a respiratory role for these processes found in oviraptorid and dromaeosaurid dinosaurs. By measuring the geometry of fossil rib cage morphology, we demonstrate that the mechanical advantage, conferred by uncinate processes, for movements of the ribs in the oviraptorid theropod dinosaur, Citipati osmolskae, basal avialan species Zhongjianornis yangi, Confuciusornis sanctus and the more derived ornithurine Yixianornis grabaui, is of the same magnitude as found in extant birds. These skeletal characteristics provide further evidence of a flow-through respiratory system in nonavian theropod [maniraptors] dinosaurs and basal avialans, and indicate that uncinate processes are a key adaptation facilitating the ventilation of a lung air sac system that diverged earlier than extant birds."

Great evidence that birds developed from Paraves. No evidence that Paraves developed from dinosaurs.


See this earlier post concerning pterosaurs and uncinate processes:
http://pterosaurnet.blogspot.com/2010/05/uncinate-processes.html

Citipati osmolskae, Zhongjianornis yangi, Confuciusornis sanctus and Yixianornis grabaui are all members of Aviremigia. They are not dinosaurs.

* Dinosaurs did not have feathers

http://news.nationalgeographic.com/news/2006/03/0315_060315_dinosaur.html

The fossil of a small, predatory dinosaur discovered in Germany has experts rethinking how feathers developed among the dinosaurs that likely gave rise to birds.

The authors say the new species undermines the notion that a covering of simple, hairlike feathers was characteristic of such early theropods as was previously believed.

Given its position in the dinosaur family tree, Juravenator "should bear filamentous feathers," Xing Xu said in an interview. But Chiappe says the new fossil didn't seem to bear any physical evidence of feathers, missing or not. "You could expect to see follicle [in the skin], small pits that contain feather buds. We don't see them in Juravenator," Chiappe said.

http://en.wikipedia.org/wiki/Juravenator

Juravenator is a genus of small (70 cm long) coelurosaurian [Compsognathidae] dinosaur, which lived in the area which would someday become the Jura mountains of Germany, about 151 or 152 million years ago.

Taking a break from pterosaurs

Here is a study:
http://www.sciencedaily.com/releases/2011/07/110718111421.htm

The face of a frog: Time-lapse video reveals never-before-seen bioelectric pattern

For the first time, Tufts University biologists have reported that bioelectrical signals are necessary for normal head and facial formation in an organism and have captured that process in a time-lapse video that reveals never-before-seen patterns of visible bioelectrical signals outlining where eyes, nose, mouth, and other features will appear in an embryonic tadpole.

https://www.youtube.com/watch?v=ndFe5CaDTlI


http://onlinelibrary.wiley.com/doi/10.1002/dvdy.22685/full

Using voltage and pH reporter dyes, we have discovered a never-before-seen regionalization of the Xenopus ectoderm, with cell subpopulations delimited by different membrane voltage and pH. We distinguished three courses of bioelectrical activity. Course I is a wave of hyperpolarization that travels across the gastrula. Course II comprises the appearance of patterns that match shape changes and gene expression domains of the developing face; hyperpolarization marks folding epithelium and both hyperpolarized and depolarized regions overlap domains of head patterning genes. In Course III, localized regions of hyperpolarization form at various positions, expand, and disappear. Inhibiting H⁺-transport by the H⁺-V-ATPase causes abnormalities in: (1) the morphology of craniofacial structures; (2) Course II voltage patterns; and (3) patterns of sox9, pax8, slug, mitf, xfz3, otx2, and pax6. We conclude that this bioelectric signal has a role in development of the face. Thus, it exemplifies an important, under-studied mechanism of developmental regulation. Developmental Dynamics 240:1889–1904, 2011. © 2011 Wiley-Liss, Inc.

ALSO:

http://link.springer.com/article/10.1007%2Fs12064-014-0200-4

In developmental and evolutionary biology, particular emphasis has been given to the relationship between transcription factors and the cognate cis-regulatory elements of their target genes. These constitute the gene regulatory networks that control expression and are assumed to causally determine the formation of structures and body plans. Comparative analysis has, however, established a broad sequence homology among species that nonetheless display quite different anatomies. Transgenic experiments have also confirmed that many developmentally important elements are, in fact, functionally interchangeable. Although dependent upon the appropriate degree of gene expression, the actual construction of specific structures appears not directly linked to the functions of gene products alone. Instead, the self-formation of complex patterns, due in large part to epigenetic and non-genetic determinants, remains a persisting theme in the study of ontogeny and regenerative medicine. Recent evidence indeed points to the existence of a self-organizing process, operating through a set of intrinsic rules and forces, which imposes coordination and a holistic order upon cells and tissue. This has been repeatedly demonstrated in experiments on regeneration as well as in the autonomous formation of structures in vitro. The process cannot be wholly attributed to the functional outcome of protein–protein interactions or to concentration gradients of diffusible chemicals. This phenomenon is examined here along with some of the methodological and theoretical approaches that are now used in understanding the causal basis for self-organization in development and its evolution.

http://www.scientificamerican.com/article/bioelectrical-signals-can-stunt-or-grow-brain-tissue/

Bioelectrical Signals Can Stunt or Grow Brain Tissue

http://www.nature.com/news/bioelectric-signals-spark-brain-growth-1.17087

Bioelectric signals spark brain growth

http://www.jneurosci.org/content/35/10/4366

http://www.sciencedaily.com/releases/2015/04/150427082851.htm

Flamingo Lineage (2)

Here is an enhancement to the possible flamingo lineage:

• Pterosaur (Ctenochasmatidae )   Pterodaustro  --->
• Presbyornithid subgroup--> 
• Primitive bird, Palaelodidae (Phoenicopteriformes)  --> 
• Flamingo (Phoenicopteriformes)

Pterosaurs lasted till late Cretaceous

Presbyornithids spanned from late Cretaceous? to Early Oligocene

Palaelodidae spanned from early Oligocene to Middle Pleistocene

Modern flamingos span from 30 mya to the present day


http://www.flamingos-world.com/flamingo-evolution.html
* There is evidence to indicate the Flamingo evolved at least 30 million years ago, perhaps longer. 

Note: I have added in the flamingos here:
http://pterosaurnet.blogspot.com/2011/10/waterfowl_07.html



http://onlinelibrary.wiley.com/doi/10.1002/ar.20990/pdf
"Our investigation of skeletal and ontogenetic variation in Pterodaustro  gives insights into  the
developmental  growth  dynamics of this  unusual  ctenochasmatid pterodactyloid   from  early
ontogeny  through  to  adulthood  and  also pro vides   information  pertaining  to  histological   variability   within   and between bones of individuals. This  study  also documents the presence of what  appears to be medullary bone tissue within the medullary cavity  of a large femur  of Pterodaustro.  This  suggests that,  like  birds,  reproductively  active female  pterosaurs  may have deposited a special bone tissue (medullary bone) to cope with  the demand of  calcium  during  eggshelling."

Summary

Here is a summary of the basic ideas of this site. This is a work in progress.:

Birds developed in a lineage from proto-pterosaurs (eg. cosesaurus)

to pterosaurs (eg. pterodactyls)

to primitive pygostylia birds (eg. enantiornithes)

to modern flying birds (neognathae) and modern flightless birds (palaeognathae).

AND

Primitive pterosaurs (rhamphorhynchids) developed into long-bony-tailed feathered creatures (eg. dromaeosaurs) which went extinct. Advanced pterosaurs (pterodactyls) developed into short-tailed feathered birds (Pygostylia).

AND

The category called "coelurosaur dinosaurs" includes only actual dinosaurs (eg. tyrannosaurs). It does not include birds.

AND

The fossil record does not support the dinosaur-to-bird idea. The fossil record does support the pterosaur-to-bird idea.

pycnofibres to feathers

breathing

warm blooded

propatagium

particular pterosaurs to particular birds

ghost lineages

finger phalanges

The Flamingo Lineage

Here is an introduction to the flamingo lineage:

A preliminary, possible lineage:

Pterosaur (Ctenochasmatidae) Pterodaustro --> Primitive bird, Palaelodidae (Phoenicopteriformes)
--> Flamingo (Phoenicopteriformes)

See this earlier post on the flamingo pterosaur:
http://pterosaurnet.blogspot.com/2010/05/flamingo.html

http://en.wikipedia.org/wiki/Pterodaustro
Pterodaustro is a genus of Cretaceous pterodactyloid pterosaur [Ctenochasmatidae] from South America, which lived 105 million years ago.

http://dinosaurs.about.com/od/aviandinosaurs3/p/pterodaustro.htm
The modern bird that's most often compared to the South American Pterodaustro is the flamingo, which this pterosaur closely resembled in appearance, if not in every aspect of its anatomy. Based on its thousand or so distinctive, bristlelike teeth, paleontologists believe that the early Cretaceous Pterodaustro dipped its curved beak into the water to filter out plankton, small crustaceans, and other tiny aquatic creatures. Since shrimp and plankton are predominantly pink, some of these scientists also speculate that Pterodaustro may have had a distinctly pinkish hue, another trait it would have shared with modern flamingos.

http://en.wikipedia.org/wiki/Pterodaustro
Pterodaustro probably waded in shallow water like flamingos, straining food with its tooth comb, a method called "filter feeding".[4] Once it caught its food, Pterodaustro probably mashed it with the small, globular teeth present in its upper jaw.
According to Robert Bakker, like with flamingos, this pterosaur's diet may have resulted in a pink hue. Thus, it is often dubbed the "flamingo pterosaur".[5]

http://pterodata.blogspot.com/2009/06/very-peculiar-pterosaur.html
"Pterodaustro is represented by a number of specimens from Argentina. There is a complete skeleton, a partial juvenile and an egg, just to mention a few. This unusual pterosaur is quite well represented in the fossil record, certainly enough is known to make a convincing reconstruction.
Most unusually, this was a filter feeder with a fine sieve of unusually adapted teeth that would have been ideal for filter feeding on small aquatic living organisms. This was the Flamingo of the ancient world!
It is also the first pterosaur where gizzard stones have been observed to be present."

http://en.wikipedia.org/wiki/Phoenicopteriformes

An extinct family of peculiar "swimming flamingos", the Palaelodidae, are believed to be related to, or to be THE ANCESTORS OF, the modern flamingos. This is sometimes rejected, since the fossil Elornis is known to be from some time before any palaelodid flamingos have been recorded.

http://en.wikipedia.org/wiki/Palaelodidae

"The Palaelodidae are a family of extinct birds in the order Phoenicopteriformes, which today is represented only by the flamingos.[1] They have been described as "swimming flamingos."

Three genera are recognised:

Adelalopus, called the "stout-legged flamingos" (Borgloon Early Oligocene of Hoogbutsel, Belgium)[2]

Palaelodus (Middle Oligocene -? Middle Pleistocene)

Megapaloelodus (Late Oligocene - Early Pliocene)"

http://en.wikipedia.org/wiki/Flamingos

"A wide variety of birds have been proposed as their closest relatives, on a wide variety of evidence. To reflect the uncertainty about this matter, flamingos are generally placed in their own order. [Phoenicopteriformes]"

http://en.wikipedia.org/wiki/Palaelodus
"Palaelodus is an extinct genus of birds distantly related to flamingos. They were slender birds with long, thin legs and a long neck. Little is known about the shape of their skull or beak. Some paleontologists think Palaelodus was able to swim under water, chasing prey, but the morphology of their feet seems not very well adapted for diving. Rather, it is more likely that they were adapted to browsing for food while swimming or standing in shallow water.
The family, Palaelodidae, is the sister taxon of modern flamingos, and the order Phoenicopteriformes, to which both belong, probably evolved from a grebe-like ancestor. It is easy to see how a bird like Palaelodus represents an intermediate form between a diving, fish-eating grebe and a wading, invertebrate-filtering flamingo. This does not mean that the palaelodids are the ancestors of the flamingos. Rather, they were a sister group that remained in the ecological niche of their common ancestor."

Since cladistics does not recognize ANCESTORS, it really means nothing to say that they "probably evolved from a grebe-like ancestor" or that  "they were a sister group". Cladistics always says something like that. That tells us nothing.
Palaelodids may well have been the ancestors of the flamingos. Anything cladistics says on that question is irrelevant.

BUT EVEN Without regard to the question of whether Palaelodus was an ancestor or a "sister taxon", we have confirmation of the idea that a separate line led to Phoenicopteriformes. 

It is one of the parallel lines I talk about.

Categories

For ease of reference, here is the list of links to the categories I have analyzed to this point. This is a work in progress.
SEE UPDATED CATEGORY LIST HERE:

http://pterosaurnet.blogspot.com/2012/02/categories-updated.html

Cladistics - Sleight of Hand

http://archosaurmusings.wordpress.com/2008/12/19/monophyletic-paraphyletic-and-polyphyletic/
"Birds are dinosaurs, that is, they are the direct descendents of an ancestor that spawned the dinosaurs, yet palaeontologists typically refer to dinosaurs while explicitly not referring to birds. Thus one should formally call them non-avian dinosaurs (basically all dinosaurs except birds)."
and
"First off the rhamphorhynchoid pterosaurs (or more properly ‘rhamphorhynchoids’ as the quotes denote it as paraphyletic) which often come up here in my frequent posts on pterosaurs. As with non-avian dinosaurs, the term persists as one of convenience as basically it’s easier to write than “non-pterodactyloid pterosaurs”."


Note the sleight of hand. 
The author says:
"Birds are dinosaurs, that is, they are the direct descendents of an ancestor that spawned the dinosaurs". 

In other words, birds did NOT evolve from dinosaurs but rather (according to the author) birds and dinosaurs evolved from some OTHER unnamed "common ancestor". 
But the author does not make this point clear at all. In fact, he misleadingly compares it to the paraphyletic (ANCESTRAL) rhamphorhynchus relationship which is a true ANCESTOR relationship - an ancestor of pterodactyls.
He talks as if they were the same type of relationship. 
Of course it is not the same relationship at all - they are opposites.

NOTE:  Birds are not even related to dinosaurs. Cladistics makes it even more difficult to establish correct ancestry. In this post I am just showing the absurdity of cladistics. If we just kept to ancestor/descendant relationships we would not have these cladistic obfuscations.

An excellent analysis of issue with cladistics:
http://joelvelasco.net/teaching/systematics/laporte%2005%20-%20single%20tree%20of%20life.pdf.

The absurdity of cladistics

http://en.wikipedia.org/wiki/Evolutionary_grade
"An evolutionary grade is a group of species united by morphological or physiological traits, that has given rise to another group that differs markedly from the ancestral condition, and is thus not considered part of the ancestral group. The ancestral group will not be phylogenetically complete (i.e. will not form a clade), so will represent a paraphyletic [ancestral] taxon".

This is the absurdity of cladistics. 
When "a group of species has given rise to another group that differs markedly from the ancestral condition, it  is not considered part of the ancestral group."

So an ANCESTOR is not an ANCESTOR!!!

I expect that not many cladists even know about the absurdity buried within cladistics.

Ancestral relationships

Here is another example of cladists struggling with an ancestral relationship. Keep in mind that cladistics does not recognize ancestral relationships.

http://en.wikipedia.org/wiki/Neoazhdarchia
"There are currently two primary but competing views of azhdarchoid relationships. The first, presented by Felipe Pinheiro and colleagues in 2011, considers the tapejarids to be a monophyletic clade including the thalassodromines and chaoyangopterines.[4] The second, found by Lu et al. 2008 as well as Naish & Martill 2006, considers the tapejarids to be a paraphyletic [ANCESTRAL] grade of primitive azhdarchoids. All azhdarchoids closer toAzhdarcho than to Tapejara are included in the clade Neoazhdarchia("new azhdarchids").[2]"

Azhdarchoidea	Azhdarchidae Tapejaridae Thalassodrominae Chaoyangopterinae Tapejarinae

Azhdarchoidea	Tapejaridae Neoazhdarchia Thalassodromidae Chaoyangopteridae Azhdarchidae

If we analyze these two competing views they actually come down to two different conclusions about the ANCESTRAL relationships.
In the first view, Azhdarchidae is the ancestor (which is not acknowledged). In the second view, Tapejaridae is the ancestor (and is acknowledged).
Since cladistics does not even recognize ancestral relationships, the cladists are stymied about how to even think about these ancestral relationships.

* "An important unanswered question"

More from this 2011 study:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028672
"The timing and sequence of events that led to the origin and subsequent evolution of flapping flight in birds remains an important unanswered question in vertebrate evolutionary biology." 


The question is "unanswered". That is quite an admission. 
The dino to bird enthusiasts themselves acknowledge that on the most important question they have no idea. 
They cannot even figure out a story to explain how a purported unknown, unfound dinosaur lineage somehow developed wings and feathers and became birds. 
It is an absurd idea. And for most of history it has been recognized as absurd. 

Enantiornithes - versatile fliers

Here is a new study that contains some very interesting material.
Here is one small part concerning Enantiornithes:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028672

Four flight styles for living birds were used:‘continuous flapping’ (CF) (e.g. grebes, ducks and auks); ‘flapping and soaring’ (FS) (e.g. storks, pelicans and large raptors); ‘flapping and gliding’ (FG) (e.g. swifts, falcons and gulls); ‘passerine-type flight’ (PT). 
AND
sampled enantiornithines fall across the range of all defined flight styles


I have proposed that enantiornithines are the ancestors of many modern bird taxa. When it comes to flight style we see the versatility within enantiornithes. 
And we already saw that they inhabited all the different niches. 

* No dino to bird lineage

It may be surprising for some people to learn that the dino to bird theory is not supported by any fossils. Those who propose the dino to bird theory acknowledge the fact that they have never found one fossil that is on the purported line from dino to bird.
There are a number of dinosaur taxa  that have been found, but it has been determined that none of them are ancestors to birds.
Even so, the dino to bird enthusiasts still imagine that birds evolved from dinosaurs.

This lack of fossils is well known but never mentioned.
All that has ever been found are dinosaur taxa that are NOT ancestors. The dino to bird theorists claim they are "sister taxa". But of course that makes no sense because there is no evidence of any actual dino to bird lineage for those sister taxa to be related to. None.
It is all imagination.