Monday, July 20, 2015

Basalmost Paraves

There is a set of 4-winged, flying primitive birds (eg. Anchiornis, Xiaotingia, Aurornis etc.) that at times have been classified as avialians and sometimes as dromaeosaurids.
But they actually belong to the basalmost Paraves.
These are the Tetrapterygidae and the Scansoriopterygids.

These 4-winged primitive birds (basalmost paraves) evolved from pterosaurs.
Later, some of these flying primitive birds settled on the ground and became secondarily flightless (eg. Eudromaeosaurids).


https://en.wikipedia.org/wiki/Paraves
the work of Xu et al. (2003), (2005) and Hu et al. (2009) provide examples of basal and early paravians with four wings,[10][11][12] adapted to an arboreal lifestyle who would only lose their hindwings when some adapted to a life on the ground and when avialans evolved powered flight.[13] Newer research also indicates that gliding, flapping and parachuting was another ancestral trait of Paraves, while true powered flight only evolved once, in the lineage leading to modern birds.[14]

https://en.wikipedia.org/wiki/Tetrapterygidae
Tetrapterygidae (meaning "four-wings") is a group of four-winged dinosaurs proposed by Sankar Chatterjee in the second edition of his book The Rise of Birds: 225 Million Years of Evolution, where he included Microraptor, XiaotingiaAurornis, and Anchiornis.[1] The group was named after the characteristically long flight feathers on the legs of all included species, as well as the theory that the evolution of bird flight may have gone through a four-winged (or "tetrapteryx") stage, first proposed by naturalist William Beebe in 1915.[2] Chatterjee suggested that all dinosaurs with four wings formed a natural group exclusive of other paravians, and that this family was the sister taxon to the group Avialae, although most phylogenetic analyses have placed the animals of his Tetrapterygidae elsewhere in Paraves, such as Xiaotingia, Aurornis, and Anchiornis being placed in Avialae.[3]

Zhenyuanlong

http://www.nature.com/srep/2015/150716/srep11775/full/srep11775.html (2015)
A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution
Regardless of the precise phylogenetic relationships of dromaeosaurids, Zhenyuanlong provides the first glimpse of feather morphologies in a short-armed dromaeosaurid. Feathers are not preserved on the holotype of Tianyuraptor, and the shortness of the forearm in this taxon led to the suggestion that its arms lacked aerodynamic function15. Although the arms of Zhenyuanlong are short, they supported large and complex wings comprised of pennaceous coverts, primaries, and secondaries, some of which are asymmetric. Whether these wings served any type of aerodynamic function is a separate question that can only be answered with biomechanical analysis, but the wings of Zhenyuanlong are strikingly similar to those of Microraptor in general size, morphology, and composition, albeit they are supported by much smaller arms.
The integumentary similarities between Zhenyuanlong and Microraptor-type animals could suggest one of several explanations. First, the large short-armed dromaeosaurids may have had some volant abilities, unrecognized previously because Tianyuraptor was preserved without feathers and its small arms were assumed to be un-flightworthy15. Perhaps there was not a large functional and behavioural gap between animals like Microraptor and Zhenyuanlong. We find this unlikely, however, given the striking differences in body size between them, and the incredibly short arms of Zhenyuanlong which do not appear optimized for flight (although we reiterate that biomechanical modelling is needed to properly test this). Alternatively, the integumentary similarities between small and clearly volant dromaeosaurids7 and larger and presumably non-volant dromaeosaurids could suggest that the larger and short-armed Zhenyuanlong evolved from more volant ancestors and maintained a many aspects of the integument through the inertia of common descent or for other selective reasons, not because it needed them for flight. It may be that such large wings comprised of multiple layers of feathers were useful for display purposes40, and possibly even evolved for this reason and not for flight, and this is one reason why they may have been retained in paravians that did not fly.
Zhenyuanlong  is a secondarily flightless member of Paraves.



Sunday, July 5, 2015

Primitive birds flying

Primitive birds (basalmost paraves) could flap their wings and fly using the same set of muscles as pterosaurs.
At times people have argued that a flying pterosaur would not devolve into a gliding primitive bird. However the evidence indicates that flying pterosaurs evolved into flying primitive birds, not into gliding primitive birds.

http://press.princeton.edu/witton/sa...pterosaurs.pdf

At one stage, it was thought that the flight muscles of
pterosaurs were very [modern] birdlike, with the arm lifted by
a muscle, m. supracoracoideus, anchoring on the sternum
rather than the shoulders. In birds, this muscle
arcs over the glenoid to attach on the dorsal surface
of the humerus, elevating the wing with a pulley-like
system (e.g., Kripp 1943; Padian 1983a; Wellnhofer
1991a). Detailed reconstruction of the proximal arm
musculature of pterosaurs shows that this is not
the case, however, and that the [pterosaur] arm was more likely
lifted by large muscles anchored on the scapula and
back, and lowered by those attached to the sternum
and coracoid
 (fig. 5.8; Bennett 2003a). Unlike [modern] birds,
where two vastly expanded muscles are mainly used
to power flight, it appears that pterosaurs used several
muscle groups to form their flapping strokes.
https://repository.si.edu/bitstream/...=1&isAllowed=y

Furthermore, the supracoracoideus muscle,
and hence an ossified sternum, is not necessary to effect the
recovery stroke of the wing.
 Thus the main evidence for
Archaeopteryx having been a terrestrial, cursorial predator is
invalidated. There is nothing in the structure of the pectoral girdle of Archaeopteryx that would preclude its having been a powered flier.


Concerning the lack of asymmetric feathers in flying basalmost paraves, the following seems relevant:

https://gwawinapterus.wordpress.com/...-introduction/

The basal deinonychosaur Anchiornis [a primitive bird] might offer a possible explanation. It had symmetrical feathers, but they were arranged in an unique away; in species with asymmetrical feathers, the most distally attached wing feathers are the longest ones. In Anchiornis, the longest are anchored near the wrist, making the center of the wing the broadest area. This is not an unusual profile among flightless maniraptors – oviraptors like Caudipteryx have this sort of arrangement as well. Anchiornis, however, differs in that the feathers at the front (as in, anchored more distally) of the longest feather decrease rapidly in size as they are closer to the end of the supporting digit; this results in a rounded, yet slightly pointy wing shape.
It is possible that this arrangement could had been an early adaptation to the demands of powered flight, before true asymmetrical feathers evolved. If so, it is possible that Anchiornis did engage in powered flight, or even a method of escape akin to rudimentary WAIR. So far, no tests have been conducted to examine the aerodynamic capacities of it’s wings.
In Anchiornis, the entire wing forms the airfoil.


https://en.wikipedia.org/wiki/Bird_flight

Elliptical wings are short and rounded, having a low aspect ratio, allowing for tight maneuvering in confined spaces such as might be found in dense vegetation. As such they are common in forest raptors (such as Accipiter hawks), and many passerines, particularly non-migratory ones (migratory species have longer wings). They are also common in species that use a rapid take off to evade predators, such as pheasants and partridges.

Altogether we have a picture of a flying, feathered, 4 winged, arboreal, primitive bird with a long bony tail, that flew like a pterosaur. With elliptical wings and symmetric feathers


Here are the aspects related to flight capability:
  • muscles used 
  • keeled or not keeled sternum 
  • flight feathers (asymmetric or not) 
  • feathered hindlimbs

Thursday, July 2, 2015

Fingers - Quick Summary

 https://en.wikipedia.org/wiki/Origin_of_birds#Digit_homology
There is a debate between embryologists and paleontologists whether the hands of theropod dinosaurs and birds are essentially different, based on phalangeal counts, a count of the number of phalanges (fingers) in the hand. This is an important and fiercely debated area of research because its results may challenge the consensus that birds are descendants of dinosaurs.
Dinosaurs have hands with digits 2-3-4-x-x. (Roman numerals represent fingers, numbers represent phalanges).
Primitive birds (basal paraves) have hands with digits x-2-3-4-x.
This is a problem for the dino to bird theory.
To overcome this problem the dino to bird folk propose changes that include the following:
  • the loss of digit I 
  • the reappearance of the lost digit IV
  • digits II-III-IV adopting the phalangeal count and characteristics of earlier digits I-II-III (frame shift) resulting in x-2-3-4-x with digit III the longest.  

The pterosaur transition (from 2-3-4-5-x) would be:
  • the loss of digit I
  • digits II-III-IV lose one phalange each, for example by adopting the phalangeal count and characteristics of earlier digits I-II-III (frame shift) resulting in x-2-3-4-x with digit IV the longest. 
Note: In the transition from pterosaur to primitive bird, the long pterosaur digit IV has been replaced with the characteristics of digit III.


Frame shift
http://www.researchgate.net/publication/259253962_Thumbs_down_a_molecular-morphogenetic_approach_to_avian_digit_homology
Thus the change of the phalangeal formula (as in the PRH) is actually caused by the change of the transcriptome (as in the FSH [frame shift hypothesis]), which in turn is directly caused by the loss of digit I (probably shh and hoxD mediated).

https://commons.wikimedia.org/wiki/File:Bird_and_dino_hand_difference_debate.JPG
Dinosaur to bird (notice the original loss of digit IV and its re-appearance)
In the diagram, Neotheropoda ( 1 ), basal tetanurae ( 2 ), a coelurosaurian ( 3 ), the bird (?)Archaeopteryx ( 4 ) and modern bird ( 5 ).

If scansoriopterygids are the basalmost members of paraves, it leads to the conclusion that the first basalmost paraves was like the scansoriopterygids. Which have x-2-3-4-x with digit IV the longest.
Which is consistent with a pterosaur ancestry and contrary to a dino ancestry.

See here for more details:
http://pterosaurnet.blogspot.ca/2014/07/pterosaur-fingers.html

Wednesday, July 1, 2015

Bristles and feathers - Quick summary

Dinosaurs (eg. tyrannosaurs) had bristles. They did not have any form of feather.
On the other hand, pterosaurs had Stage I and Stage II feathers. Those early stage feathers kept the endothermic pterosaur warm, which was necessary in flying.
Primitive birds (basal paraves) had pennaceous feathers. Those pennaceous feathers developed in the transition from pterosaur to primitive bird.

In order to understand this topic, it is essential to understand the development stages a feather goes through.
Drawing B represents Stage I. Note that the follicle appears at Stage II (drawing C):








See here for more details:
http://pterosaurnet.blogspot.ca/2014/01/helpful-background.html

Friday, June 26, 2015

Primitive birds - Quick summary

There were pennaceous-feathered, long-bony-tailed primitive birds.
The most basal were flying (eg. scansoriopterygids, tetrapterygids).
Some later ones became secondarily flightless (eg. oviraptors, eudromaeosaurids etc).

These primitive birds have a great deal in common with pterosaurs. They evolved from pterosaurs.
These primitive birds have almost nothing in common with dinosaurs.

Scansoriopterygid



Oviraptor (secondarily flightless)


Monday, June 22, 2015

Oviraptor Propatagium

More evidence that oviraptors were secondarily flightless and not transitional between dinosaurs and Paraves.

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCMQFjAB&url=https%3A%2F%2Fbio.unc.edu%2Ffiles%2F2011%2F04%2FFeducciaCzerkas2015.pdf&ei=YEiHVfvbLMWRyAS67JKYBQ&usg=AFQjCNEJgIr2smR2Fi7zU35DviaiAu1sVg&sig2=R0xmD8EIWD2vnj8Zf__yMw&bvm=bv.96339352,d.aWw
Testing the neoflightless hypothesis: propatagium reveals flying ancestry of oviraptorosaurs (2015)
Alan Feduccia1• Stephen A. Czerkas2
Considerable debate surrounds the numerous
avian-like traits in core maniraptorans (oviraptorosaurs,
troodontids, and dromaeosaurs), especially in the
Chinese Early Cretaceous oviraptorosaur Caudipteryx,
which preserves modern avian pennaceous primary remiges
attached to the manus, as is the case in modern birds.
Was Caudipteryx derived from earth-bound theropod dinosaurs,
which is the predominant view among palaeontologists,
or was it secondarily flightless, with volant avians
or theropods as ancestors (the neoflightless hypothesis),
which is another popular, but minority view. The discovery
here of an aerodynamic propatagium in several specimens
provides new evidence that Caudipteryx (and hence oviraptorosaurs)
represent secondarily derived flightless
ground dwellers, whether of theropod or avian affinity
,
and
that their presence and radiation during the Cretaceous may
have been a factor in the apparent scarcity of many other
large flightless birds during that period.
There is actually no link between dinosaurs and Paraves.

See here for more details about oviraptors as secondarily flightless:
http://pterosaurnet.blogspot.ca/2014/09/oviraptors-as-secondarily-flightless.html

Friday, June 5, 2015

Dinosaurs are not similar to primitive birds

The following study shows that there were 51 synapomorphies (unique defining characteristics) for Paraves (primitive birds). This means that of the 374 characteristics that were evaluated, 51 of them were different than the claimed dinosaur ancestor. This is more than 1 in 8. This means that primitive birds are not similar to dinosaurs, which is a point that I have being making for a very long time. It is good to see a cladistic analysis confirm this point. 
Note that this number would be very much larger if the oviraptors etc were taken as secondarily flightless.

2011 study (Xu et al):
http://www.nature.com/nature/journal/v475/n7357/full/nature10288.html
http://www.ivpp.cas.cn/qt/papers/201403/P020140314389417822583.pdf
 An Archaeopteryx-like theropod [Xiaotingia] from China and the origin of Avialae
Here we report a new Archaeopteryx-like theropod from China. This find further demonstrates that many features formerly regarded as being diagnostic of Avialae, including long and robust forelimbs, actually characterize the more inclusive group Paraves (composed of the avialans and the deinonychosaurs). 
Paraves: 1.1, 10.1, 13.0, 14.0, 15.1, 20.1, 21.1, 28.1, 39.0, 61.1, 65.0, 66.0, 69.0, 79.0, 91.0,95.0, 96.1, 97.1, 106.0, 109.1, 119.1, 125.0, 127.1, 129.1, 137.1, 138.1, 139.1, 154.0, 155.1,156.1, 160.1, 166.0, 176.1, 179.1, 180.1, 184.1, 202.1, 221.1, 232.0, 237.1, 262.1, 267.1,277.2, 292.0, 304.2, 306.1, 319.1, 320.2, 336.1, 354.0, and 362.1

Saturday, May 2, 2015

Another scansoriopterygid intermediate

Yi qi study:


A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings 

The wings of birds and their closest theropod relatives share a uniform fundamental architecture, with pinnate flight feathers as the key component1, 2, 3. Here we report a new scansoriopterygid theropod, Yi qi gen. et sp. nov., based on a new specimen from the Middle–Upper Jurassic period Tiaojishan Formation of Hebei Province, China4. Yi is nested phylogenetically among winged theropods but has large stiff filamentous feathers of an unusual type on both the forelimb and hindlimb. However, the filamentous feathers of Yi resemble pinnate feathers in bearing morphologically diverse melanosomes5. Most surprisingly, Yi has a long rod-like bone extending from each wrist, and patches of membranous tissue preserved between the rod-like bones and the manual digits. Analogous features are unknown in any dinosaur but occur in various flying and gliding tetrapods6, 7, 8, 9, 10, suggesting the intriguing possibility that Yi had membranous aerodynamic surfaces totally different from the archetypal feathered wings of birds and their closest relatives. Documentation of the unique forelimbs of Yi greatly increases the morphological disparity known to exist among dinosaurs, and highlights the extraordinary breadth and richness of the evolutionary experimentation that took place close to the origin of birds.
Supplementary information:
If a membrane is reconstructed lateral to the trunk, the wing is similar in outline to ........ a pterosaur wing if the styliform element is approximately laterally oriented.
Extended data:
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14423.html#extended-data

Abstract:
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14423.html




If the Xu et al interpretation is correct, then Yi qi is the perfect candidate for transitional between pterosaur and paraves.


Here are a few other references:
http://phenomena.nationalgeographic.com/2015/04/29/chinese-dinosaur-had-bat-like-wings-and-feathers/
These wings were mutually exclusive: dinosaur or pterosaur, feathery or leathery. But Yi went for both options! It had membrane wings with a feathery covering on the leading edge. It shows that at least some dinosaurs had independently evolved the same kind of wings as pterosaurs—an extraordinary example of convergent evolution.

http://www.nature.com/articles/nature14392.epdf?referrer_access_token=ZfVGgFg7XRdurry3TN0QoNRgN0jAjWel9jnR3ZoTv0PiQtvFAER-nO6rVanRtj7cIVRMaXAe5x5JlY3vpNDkkxI0a1Q8_ZTmq63AsO-pCE_wZ6-LixrY3IBCK0O57ofs-sVhrdtkwoPKG1MmYYRWBnKtWySldMOVBfPZhs5YnU3psTTjZa6_HEcPzvjKZvRO962MU9ssjnM38C1xE3d-slSGO5xkY9Myf0Z8kfmYNxU%3D&tracking_referrer=www.nature.com

http://www.nature.com/news/more-on-unicorns-1.17419
It is here that we enter unicorn territory for no dinosaur, however unusual, has been found with anything like this feature. The authors are appropriately cautious, therefore, in their interpretation.
http://www.theguardian.com/science/lost-worlds/2015/apr/29/bird-yi-qi-the-dinosaur-evolution-flight-feather-nature

https://whyevolutionistrue.wordpress.com/2015/04/30/dino-bat-a-new-flying-dinosaur-with-membranous-wings/

https://www.sciencenews.org/article/dinosaur%E2%80%99s-ride-may-have-been-glide
A dinosaur called Yi qi appears to have lifted a page from pterosaurs’ flight plan. Protruding from each of the newly discovered dinosaur’s wrists was a weird rodlike bone that may have attached to a fleshy wing that helped the dinosaur glide or fly, researchers report April 29 in Nature.“We’ve never seen anything like this in a dinosaur before,” says paleontologist Sarah Werning of Stony Brook University in New York. “It’s almost like this dinosaur was pretending to be a pterosaur.”

Xu et al "identify the three manual digits of Yi and other maniraptors as II-III-IV".
http://www.nature.com/articles/natur...www.nature.com (2015)

On the other hand, if the Xu et al interpretation is wrong, then this is significant:
The highly elongated manual digit IV of Yi and other scansoriopterygids is unique among theropods but superficially similar to ...... the highly elongated fourth finger in pterosaurs. (page 71)

Friday, January 9, 2015

Dino to bird - off on the wrong foot

The revival of the dino to bird idea began with the work of John Ostrom in the 1970's. But Ostrom made the misinterpreted the secondarily flightless Deinonychus as a land-based transitional between dinosaur and Paraves.
It is now clear that Deinonychus is a secondarily flightless member of Paraves. It is a dromaeosaur which is included in Paraves. "Secondarily" means that it descended from a flying ancestor.
The current dino to bird theory revival dates back to Ostrom's misinterpretation in the 1970's.
There is no connection between actual dinosaurs and Paraves.

Relevant links:
https://books.google.ca/books?id=SihlpQTlVdAC&pg=PA255&dq=secondarily+flightless+Deinonychus&hl=en&sa=X&ei=u_WpVKGHIYqHyQSDgIGgAw&ved=0CB4Q6AEwAA#v=onepage&q=secondarily%20flightless%20Deinonychus&f=false


https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAA&url=http%3A%2F%2Fdinosaur-museum.org%2Ffeatheredinosaurs%2FAre_Birds_Really_Dinosaurs.pdf&ei=2DBZVYGeK9WnyASXjoHwCg&usg=AFQjCNEJrFq0orAoklv1snX0OPSZFHKKnA&sig2=VoQeE-VSU4vYesMMyaNZCw&bvm=bv.93564037,d.aWw
With the benefit of hindsight it is easy to see that if fossils of the
small flying dromaeosaurs from China had only been discovered before the larger flightless dromaeosaurs
like Deinonychus or Velociraptor were found, the interpretations of the past three decades on how birds
are related to dinosaurs would have been significantly different. If it had already been established that
dromaeosaurs were birds that could fly, then the most logical interpretation of larger flightless
dromaeosaurs found afterwards would have to be that they represented birds, basically like the prehistoric
equivalent of an Ostrich, which had lost their ability to fly.

They even have a category for the secondarily flightless members of Dromaeosauridae:
http://en.wikipedia.org/wiki/Eudromaeosauria
Quote:
Eudromaeosaurs
Temporal range: Early Cretaceous – Late Cretaceous, 143–66Ma

Eudromaeosauria ("true dromaeosaurs") is a subgroup of terrestrial dromaeosaurid theropod dinosaurs. They were relatively large-bodied, feathered hypercarnivores (with diets consisting almost entirely of other terrestrial vertebrates) that flourished in the Cretaceous Period.

http://www.bio.fsu.edu/James/Ornithological%20Monographs%202009.pdf
If some maniraptorans were
birds, and if birds were not theropods, similarities
between [flightless] maniraptorans and theropods could
be readily explained by convergence on a cursorial
morphotype subsequent to the loss of flight.
Even distantly related reptiles could converge
closely, in some cases almost indistinguishably,
on the theropod morphotype through the acquisition
of cursoriality, as the case of Effigia, noted
above, dramatically demonstrates (Nesbitt and
Norell 2006, Nesbitt 2007). If this is the case, some
maniraptorans represent lineages of cryptic birds
whose true phylogenetic relationships have been
obscured by convergence and the loss of flight.
Given the evidence that some maniraptorans
may belong within Aves and that, consequently,
Aves may not belong within Theropoda, this possibility
must be seriously considered.
In the case of Effigia, the trend toward bipedalism produced extreme convergence throughout the cranial and
postcranial skeleton on that of highly cursorial
ornithomimosaurs, with further convergence on
numerous characters of the avemetatarsalian,
dinosaurian, theropod, neotetanurine, and coelurosaurian
skeletons; in some cases, the relevant
characters are identical across taxa (Nesbitt and
Norell 2006, Nesbitt 2007).

The groups that were originally thought to provide support for a dino to bird theory (eg. Archaeoptryx, Deinonychus) are no longer considered to be related to the purported line from dinosaur to Paraves. Rather they are members of Paraves. 


http://en.wikipedia.org/wiki/Deinonychus
Several years later, Ostrom noted similarities between the forefeet of Deinonychus and that of birds, an observation which led him to revive the hypothesis that birds are descended from dinosaurs.[34]
http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8312.1976.tb00244.x/epdf

http://biostor.org/reference/110202.text
http://biostor.org/reference/110202
Saurischian monophyly and the origin of birds
Jacques Gauthier
Ostrom (1976)
http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8312.1976.tb00244.x/epdf

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCMQFjAB&url=https%3A%2F%2Fbio.unc.edu%2Ffiles%2F2011%2F04%2FFeducciaCzerkas2015.pdf&ei=YEiHVfvbLMWRyAS67JKYBQ&usg=AFQjCNEJgIr2smR2Fi7zU35DviaiAu1sVg&sig2=R0xmD8EIWD2vnj8Zf__yMw&bvm=bv.96339352,d.aWw
Following their discovery, dromaeosaurs
were initially thought to be flightless nonavian
dinosaurs ancestral to actual birds which eventually
evolved the ability to fly; hence, according to this
hypothesis, avian aerodynamic adaptations evolved by
exaptations in earth-bound forms (Sereno 1999). The
dromaeosaurs therefore appeared to represent feathered
dinosaurs which were wingless ancestors of birds that
were not yet capable of flight. However, with the discovery
of fully volant basal dromaeosaurs, the microraptors,
with a four-winged, tetrapteryx bauplan and
avian pennaceous, asymmetric flight remiges, the concept
of a dinosaurian trees-down model was introduced
(Zhou and Zhang 2006; Chatterjee and Templin 2012).
Also interesting:

http://en.wikipedia.org/wiki/Origin_of_birds
In 1969, this dinosaur was described and named Deinonychus by John Ostrom of Yale University.[24] The next year, Ostrom redescribed a specimen of Pterodactylus in the Dutch Teyler Museum as another skeleton of Archaeopteryx.[25] The specimen consisted mainly of a single wing and its description made Ostrom aware of the similarities between the wrists of Archaeopteryxand Deinonychus.[26] 

http://en.wikipedia.org/wiki/Origin_of_birds#Secondary_flightlessness_in_dinosaurs
A hypothesis, credited to Gregory Paul and propounded in his books Predatory Dinosaurs of the World (1988) and Dinosaurs of the Air (2002), suggests that some groups of non-flying carnivorous dinosaurs—especially deinonychosaurs, but perhaps others such as oviraptorosaurs, therizinosaurs, alvarezsaurids and ornithomimosaurs—actually descend from birds. 
http://www.researchgate.net/publication/227857345_Birds_have_paedomorphic_dinosaur_skulls


https://en.wikipedia.org/wiki/Archaeopteryx
Because it displays a number of features common to both birds and non-avian dinosaurs, Archaeopteryx has often been considered a link between them.[11] In the 1970s, John Ostrom, following T. H. Huxley's lead in 1868, argued that birds evolved within theropod dinosaurs and Archaeopteryx was a critical piece of evidence for this argument; it had a number of avian features, such as a wishbone, flight feathers, wings, and a partially reversed first toe along with a number of dinosaur and theropod features. For instance, it has a long ascending process of the ankle bone, interdental plates, anobturator process of the ischium, and long chevrons in the tail. In particular, Ostrom found that Archaeopteryx was remarkably similar to the theropod family Dromaeosauridae.[14][15][16][17][18][19][20][21][22]

-------------------------------------------------------------------

2011 study (Xu):
http://www.nature.com/nature/journal/v475/n7357/full/nature10288.html
http://www.ivpp.cas.cn/qt/papers/201403/P020140314389417822583.pdf
An Archaeopteryx-like theropod from China and the origin of Avialae
Archaeopteryx is widely accepted as being the most basal bird, and accordingly it is regarded as central to understanding avialan origins; however, recent discoveries of derived maniraptorans have weakened the avialan status of Archaeopteryx. Here we report a new Archaeopteryx-like theropod from China. This find further demonstrates that many features formerly regarded as being diagnostic of Avialae, including long and robust forelimbs, actually characterize the more inclusive group Paraves (composed of the avialans and the deinonychosaurs). Notably, adding the new taxon into a comprehensive phylogenetic analysis shifts Archaeopteryx to the Deinonychosauria. Despite only tentative statistical support, this result challenges the centrality ofArchaeopteryx 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.
(Characters 1-363 are from Hu et al. (2009), whereas 364-374 are newly
added). 
Deinonychosauria: 29.1, 72.1, 75.1, 82.0, 111.1, 134.1, 171.2, 183.1, 189.0, 199.1, 233.1,
238.0, 255.0, 294.1, 297.1, 302.1, 323.1, 334.1, 335.2, 359.0, 364.0, 365.0, 366.1, 367.0,
368.0, 371.0, and 372.1 
Paraves: 1.1, 10.1, 13.0, 14.0, 15.1, 20.1, 21.1, 28.1, 39.0, 61.1, 65.0, 66.0, 69.0, 79.0, 91.0,
95.0, 96.1, 97.1, 106.0, 109.1, 119.1, 125.0, 127.1, 129.1, 137.1, 138.1, 139.1, 154.0, 155.1,
156.1, 160.1, 166.0, 176.1, 179.1, 180.1, 184.1, 202.1, 221.1, 232.0, 237.1, 262.1, 267.1,
277.2, 292.0, 304.2, 306.1, 319.1, 320.2, 336.1, 354.0, and 362.1
Paraves-Oviraptorosauria-Therizinosauroidea clade: 13.1, 14.1, 28.0, 29.0, 39.1, 41.2, 54.0,
66.2, 79.1, 91.2, 106.1, 116.1, 117.1, 119.0, 121.1, 125.1, 126.1, 127.0, 130.1, 131.1, 136.1,
144.1, 157.2, 166.2, 167.2, 200.1, 238.1, 255.1, 276.1, 284.1, 300.1, 329.1, 351.1, 354.1,
359.1, 363.1, 364.1, 365.1, 367.1, 368.1, and 371.1.

2008 study (Zhang)
www.ivpp.ac.cn/qt/papers/201206/P020120601535055482173.pdf
http://www.nature.com/nature/journal/v455/n7216/suppinfo/nature07447.html
A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers
Characters 361-363 are newly added. Characters 4, 25, 33, 40-42, 65, 67, 69, 82, 85, 91,
99, 106, 110, 115, 116, 121, 122, 136, 138, 142, 146, 148, 151, 153, 163, 165-167,
169, 171, 178, 181, 200-203, 212, 230-360 are from Senter (2007); others are from
Kirkland et al. (2005).

2009 study (Hu, D.Y. et al)
A pre-Archaeopteryx troodontid from China with long feathers on the
metatarsus. Nature 461, 640-643

2009 study (Nesbitt)
http://onlinelibrary.wiley.com/doi/10.1002/jmor.10724/pdf

2010 study
Xu, X., Ma, Q.-Y. & Hu, D.-Y. Pre-Archaeopteryx coelurosaurian dinosaurs and their
implications for understanding avian origins. Chin. Sci. Bull. 55, 3971–3977
www.ivpp.ac.cn/qt/papers/201403/P020140314383143868220.pdf

2011 study (Nesbitt)
http://digitallibrary.amnh.org/dspace/handle/2246/6112
Includes basal pterosaurs.

2012 study (Michael S. Y. Lee):
http://rsbl.royalsocietypublishing.org/content/8/2/299

2012 study (Senter)
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0036790

2013 study (Pascal Godefroit):
http://www.nature.com/nature/journal/v498/n7454/full/nature12168.html
http://www.nature.com/nature/journal/v498/n7454/full/nature12168.html#supplementary-information

2013 (Andres)
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9036361&fileId=S1755691013000303

2014 study (Stephen L. Brusatte)
http://www.cell.com/current-biology/abstract/S0960-9822(14)01047-1
http://webcache.googleusercontent.com/search?q=cache:Xh48ucIC9jMJ:https://datadryad.org/bitstream/handle/10255/dryad.69251/BrusatteetalRevisionDryadFile1.docx%3Fsequence%3D1+&cd=2&hl=en&ct=clnk&gl=ca

2001 study (Norell)
https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&uact=8&ved=0CDwQFjAG&url=http%3A%2F%2Fpeabody.yale.edu%2Fsites%2Fdefault%2Ffiles%2Fdocuments%2Fscientific-publications%2FNorell.pdf&ei=WTJzVdm3J8-cyQTE04LIBQ&usg=AFQjCNHXFS86E3amp_s8Rawptna25kZgsg&sig2=JE9mqQQXJJD-gsBoEy9qCw&bvm=bv.95039771,d.aWw

2004 study (Renesto)
http://dipbsf.uninsubria.it/paleo/vallesaurus.pdf
Includes one pterosaur

Unwin
https://books.google.ca/books?id=8CKYxcylOycC&pg=PA151&lpg=PA151&dq=pterosaur+humerus+femur&source=bl&ots=SqlVhvxEf8&sig=rFe60Gylylfa_tjGGNALcIenUuU&hl=en&sa=X&ved=0CB0Q6AEwAGoVChMI99bb_IyExgIVho6SCh23TABo#v=onepage&q=pterosaur%20humerus%20femur&f=false

2007 study (Senter)
http://www.tandfonline.com/doi/abs/10.1017/S1477201907002143

Tuesday, January 6, 2015

Dinosaur to bird - implausible rates of change

For the dino to bird theory to be correct, the evolutionary rates must have been up to four times faster. But that would mean that for the dino to bird theory to be correct, it would require rates of evolution comparable to those in the Cambrian Explosion. Not plausible.

http://www.bbc.co.uk/nature/28563682
Huge meat-eating, land-living dinosaurs evolved into birds by constantly shrinking for over 50 million years, scientists have revealed.
Theropods shrunk 12 times from 163kg to 0.8kg before becoming modern birds.
The researchers found theropods were the only dinosaurs to get continuously smaller.
Their skeletons also changed four times faster than other dinosaurs, helping them to survive.
They found that the dinosaur group directly related to birds shrank rapidly from about 200 million years ago.
It showed a decrease in body mass of 162.2kg (25st 7lb) from the largest average body size to Archaeopteryx, the earliest known bird.
These bird ancestors also evolved new adaptations, including feathers, wishbones and wings, four times faster than other dinosaurs.
Shrinking and new bird-like traits jointly influenced the transition of dinosaurs to birds, researchers say.
The researchers concluded that the evolution of the branch of dinosaurs leading to birds was more innovative than other dinosaur lineages.

http://blogs.scientificamerican.com/tetrapod-zoology/2014/07/31/50-million-years-of-shrinking-theropod-dinosaurs/

Because our results allow us to map the appearance dates of lineages onto the phylogeny, we can see that evolutionary rates across part of the lineage leading to birds occurred much faster than expected compared to the rest of the tree – up to four times faster, in fact (Lee et al. 2014a). This seemingly explains why several groups of tetanuran theropods – allosauroids, tyrannosauroids, compsognathids and others – appear near-simultaneously in the fossil record: it seems that the time intervals between their originations really were very short. Why evolution was occurring so rapidly in these animals remains, of course, an unknown.
According to the dino to bird theory, Paraves appeared "near-simultaneously" with its purported coelurosaur dinosaur ancestor . This is no longer evolution theory. This is creationism.


The study itself:

Abstract:
http://www.sciencemag.org/content/345/6196/562

Full study:
http://www.researchgate.net/publication/264386153_Sustained_miniaturization_and_anatomical_innovation_in_the_dinosaurian_ancestors_of_birds

The study Supplementary Material:
https://www.academia.edu/7832790/Lee_M.S.Y._Cau_A._Naish_D._Dyke_G.J._2014._Sustained_miniaturization_and_anatomical_innovation_in_the_dinosaurian_ancestors_of_birds._Science_345_562-566_NOTE_SM_below_has_hi-res_figures_which_were_pixellated_on_the_Science_SM_pdf_




Also see here:
http://pterosaurnet.blogspot.ca/2014/03/body-size-and-forelimb-length.html


Comparison with the Cambrian Explosion 

https://www.academia.edu/4371818/Lee_M.S.Y._Soubrier_J._and_Edgecombe_G.D._2013._Rates_of_phenotypic_and_genomic_evolution_during_the_Cambrian_Explosion._Current_Biology_23_1889-1895_4_files_-_main_text_2_SI_files_Commentary_
The near-simultaneous appearance of most modern animal body plans (phyla) ~530 million years ago during the Cambrian explosion is strong evidence for a brief interval of rapid phenotypic and genetic innovation, yet the exact speed and nature of this grand adaptive radiation remain debated [1–12]. Crucially, rates of morphological evolution in the past (i.e., in ancestral lineages) can be inferred from phenotypic differences among living organisms—just as molecular evolutionary rates in ancestral lineages can be inferred from genetic divergences [13]. We here employed Bayesian [14] and maximum likelihood [15] phylogenetic clock methods on an extensive anatomical[16]and genomic[17] data set for arthropods, the most diverse phylum in the Cambrian and today. Assuming an Ediacaran origin for arthropods, phenotypic evolution was ~4 times faster, and molecular evolution ~5.5 times faster, during the Cambrian explosion compared to all subsequent parts of the Phanerozoic. These rapid evolutionary rates are robust to assumptions about the precise age of arthropods. Surprisingly,these fast early rates do not change substantially even if the radiation of arthropods is compressed entirely into the Cambrian (~542 mega-annum [Ma]) or telescoped into the Cryogenian (~650 Ma). The fastest inferred rates are still consistent with evolution by natural selection and with data from living organisms, potentially resolving ‘‘Darwin’s dilemma.’’ However, evolution during the Cambrian explosion was unusual (compared to the subsequent Phanerozoic) in that fast rates were present across many lineages.
This means that the dino to bird theory is right up there with the Cambrian Explosion in terms of it being very unusual.
The near-simultaneity and the much faster rates of evolution required by the dino to bird theory are VERY UNUSUAL. As unusual as the Cambrian Explosion.


Also:
http://www.evolutionnews.org/2013/09/how_to_solve_th076861.html

http://www.uncommondescent.com/intelligent-design/darwins-dilemma-remains-unresolved-what-lees-paper-didnt-discuss/


Thursday, January 1, 2015

How did birds come into being?

How did birds come into being?
First we must distinguish between modern birds on the one hand, and their feathered ancestors called "basal paraves" on the other.
Basal paraves were feathered, long-bony-tailed, flying creatures (eg. scansoriopteryx). No modern birds have long-bony-tails.

So the question becomes, how did basal paraves come into being?
The dinosaur to bird theory suggests that basal paraves evolved from coelurosaur dinosaurs (eg. tyrannosaurs).
The pterosaur to bird theory suggests that basal paraves evolved from pterosaurs (eg. rhamphorhynchids). 
The topic immediately becomes complicated, because there is a set of feathered, long-bony-tailed creatures that did not fly (eg. oviraptors, alvarezsaurids).
The dinosaur to bird theory views these creatures as transitional between ground-based coelurosaur dinosaurs and flying basal paraves. They call them "non-paraves maniraptors".
The pterosaur to bird theory views these creatures as secondarily flightless* members of basal paraves.

It is important to realize that according to the fossil record, all these flightless, feathered creatures came after (closer to today than) the flying members of basal paraves.
This is straightforwardly consistent with them being secondarily flightless. On the other hand, for them to be transitional between dinosaurs and flying basal paraves, requires purported lengthy ghost lineages (up to tens of millions of years in length) and purported exaptations.



* An ostrich is an example of a "secondarily flightless" modern bird.

Wednesday, December 17, 2014

Pubis evolution


http://pterosaurheresies.files.wordpress.com/2011/09/prepubes588.jpg
Pterosaur pubis (in green) and prepubis (in yellow). The drawing of MPUM 6009 is the most relevant.



The pterosaur pubis (green) is homologous with the basal paraves superior pubic ramus and pubic body.
The pterosaur prepubis (yellow) is homologous with the basal paraves inferior pubic ramus.


http://archosaurmusings.wordpress.com/2009/12/24/back-to-that-pterosaur-sacrum-pelvis/
pterosaurs also have a fourth pelvic bone in the form of the pre-pubis. This pair of bones (one for each side) lie, and no points for guessing this, in front of, and articulate with, the pubes.
http://pterosaurheresies.wordpress.com/tag/pterosaur-evolution/page/6/
The prepubis of pterosaurs is a pelvic bone not found in the vast majority of tetrapods. It is not homologous with the prepubis of monotremes and marsupials. Nor is it homologous with the so-called “prepubic” bones of crocodilians, which are homologous with the pubic bones of other amniotes (Seeley 1901). The prepubis of ornithischian dinosaurs is a process of the pubis and not a separate ossification.
For example:
The pubis/prepubis parts of MPUM 6009 above, correspond to the 3 parts of the paraves pubis, as seen in the oviraptor pubis in drawing "C" below. 

http://qilong.files.wordpress.com/2011/07/caenagnathid-ilia.jpg?w=932&h=549




Sunday, December 14, 2014

Feet

Pterosaur feet are like basal paraves feet. Dinosaur feet are not like basal paraves feet.

ivpp.cas.cn/qt/papers/201403/P020140314393548274893.pdf
Distally the [Epidendrosaurus] trochlea of metatarsal I aligns with those of II and III as in advanced perching birds, but not in other known dinosaurs.
The foot of Epidendrosaurus [a Scansoriopterygidae] is unique among nonavian
theropods. Although it does not preserve a reversed
hallux, metatarsal I is articulated with metatarsal II at
such a low position that the trochleae of metatarsals I–IV
are almost on the same level (see Figs. 1, 2d), which
is similar to those of perching birds including the Early
Cretaceous flying birds Sinornis (Sereno 1992) and
Longipteryx (Zhang and Zhou 2001), as well as many arboreal
pterosaurs.
http://en.wikipedia.org/wiki/Scansoriopteryx
It [Scansoriopteryx] also had an unusually large first toe, or hallux, which was low on the foot and may have been reversed, allowing some grasping ability.[1]
The Scansoriopterygidae are among the most basal members of Paraves.


http://www.nature.com/nature/journal.../391886a0.html
Other features of digits I-IV of the D. weintraubi foot indicate a capacity for grasping that is consistent with an ability to climb but is unexpected in an obligate cursor. The claws are moderately curved (nearly as strongly as the claws of the manus); all phalanges except the most proximal have well developed flexor tubercles for the insertion of digital flexors (Fig. 2); and all of the IP joints allow for extensive flexion of the digits (as exhibited by digit IV; Fig. 2). Furthermore, the phalangeal proportions of the digits of Dimorphodon and other basal pterosaurs are similar to those of birds with grasping feet (that is, perching, climbing, and raptorial species) and unlike those of primarily ground-living birds, bipedal dinosaurs and the primitive dinosauromorphs Lagerpeton and Marasuchus.

Friday, December 12, 2014

Notable

http://www.ivpp.ac.cn/qt/papers/201206/P020120604508520389814.pdf
The [Epidendrosaurus] material described in this paper was collected from a new locality, Daohugou, in east Nei Mongol, northeast China, which is west of Liaoning Province. Many salamanders(Wang 2000), plants and insects (Zhang 2002)have recently been discovered from this new locality. It is notable that an anurognathid rhamphorhynchoid pterosaur [Jeholopterus] with beautiful hair [pycnofibers] covering the whole body has also been reported from this locality (Wang et al. 2002). The estimated age of the deposit at this locality is very controversial and ranges from the Middle Jurassic or the Early Cretaceous according to various authors (Wang etal. 2000; Zhang 2002); however, most workers currently regard it as being Late Jurassic.
Epidendrosaurus is a Scansoriopterygidae and one of the most basal members of Paraves.


http://link.springer.com/article/10.1360/02tb9054#page-1
We report a new and nearly completely articulated rhamphorhynchoid pterosaur, Jeholopterus ningchengensis gen. et sp. nov., with excellently preserved fibres in the wing membrane and “hairs” in the neck, body and tail regions.
https://scholar.google.com/scholar_lookup?title=A+nearly+completely+articulated+rhamphorhynchoid+pterosaur+with+exceptionally+well-preserved+wing+membranes+and+%22hairs%22+from+Inner+Mongolia,+northeast+China&author=WANG+X&author=ZHOU+Z&author=ZHANG+F&author=XU+X&publication_year=2002&journal=Chin+Sci+Bull&volume=47&pages=226-230


http://en.wikipedia.org/wiki/Jeholopterus
Jeholopterus was a small anurognathid pterosaur from the Middle to Late Jurassic[1]Daohugou Beds of the Tiaojishan Formation of Inner MongoliaChina , preserved with hair-like pycnofibres and skin remains.

http://en.wikipedia.org/wiki/Yi_%28dinosaur%29
The only known Yi qi fossil was found in rocks assigned to the Tiaojishan Formation, dating to the Callovian-Oxfordian age of the Middle-Late Jurassic,[1] dated to between 165 and 153 million years ago.[3] This is the same formation (and around the same age) as the other known scansoriopterygids Epidexipteryx and Scansoriopteryx.

Yi qi