Tuesday, October 13, 2015

From pterosaur to primitive bird

Here is a draft of the lineage from pterosaur to primitive bird (click to enlarge):

If anyone has a comment or a question, please feel free to submit it.

Monday, October 12, 2015

Jeholornis and Oviraptors

I suggest that secondarily flightless oviraptors descended from a flying creature like Jeholornis. Notice the similarities in morphology, time and location.

Jeholornis (meaning "Jehol bird") is a genus of avialans that lived between approximately 122 and 120 million years ago during the early Cretaceous Period in China. Fossil Jeholornis were first discovered in the Jiufotang Formation in Hebei Province, China (in what was previously Rehe Province, also known as Jehol—hence the name) and additional specimens have been found in the older Yixian Formation.[1] Jeholornis had long tails and few small teeth, and were approximately the size of turkeys,[2] making them among the largest avialans known until the Late Cretaceous. Their diet included seeds of cycadsGinkgo or similar plants. Jeholornis were relatively large, primitive avialans, with a maximum adult length of up to 80 cm (2.6 ft).[2] Their skulls were short and high, similar to other primitive avialans like Epidexipteryx and to early oviraptorosaurs like Incisivosaurus.
Avialae is also occasionally defined as an apomorphy-based clade (that is, one based on physical characteristics). Jacques Gauthier, who named Avialae in 1986, re-defined it in 2001 as all dinosaurs that possessed feathered wings used in flapping flight, and the birds that descended from them.[8][9]
Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or without bony crests atop the head. They ranged in size from Caudipteryx, which was the size of a turkey, to the 8 metre long, 1.4 ton Gigantoraptor.[4] The group (along with all maniraptoran dinosaurs) is close to the ancestry of birds. Analyses like those of Maryanska et al (2002) and Osmólska et al. (2004) suggest that they may represent primitive flightless birds.[5][6]
Caudipteridae is a family of oviraptorosaurian dinosaurs known from the Early Cretaceous of China. Found in the Yixian and Jiufotang Formations, the group existed between 125-120 million years ago.
Protarchaeopteryx (meaning "before Archaeopteryx") is a genus of turkey-sized feathered theropod dinosaur from China.[1] Known from the Jianshangou bed of the Yixian Formation, it lived during the early Aptian age of the Early Cretaceous, approximately 124.6 million years ago.[2]



Here is how the secondarily flightless oviraptors could fit into the picture (click to enlarge):

Here is how the secondarily flightless ornithomimosaurs, alvarezsaurids and oviraptors could fit into the picture:

This shows the transition from pterosaur:

Sunday, October 11, 2015


There are many problems with the analyses of the dino to bird theory. This is one of them:

Also, the use of bipedal coelurosaurian
outgroups, as in the analysis by Clark et
al. (2002), may be contributing to a potentially
misleading topology. Outgroup choice determines
the polarity of character states, including
ancestral reconstructions for entire clades (Nixon
and Carpenter 1993). In this case, using bipedal
cursors as outgroups may obscure phylogenetic
signal by wrongly treating characters indicating
flight loss as plesiomorphy.
The "maniraptors" such as oviraptors and ornithomimosaurs were flightless. They lived on the ground. The question is whether their ancestor was a ground-living creature (such as a dinosaur) or whether their ancestor was a flying, primitive bird.
When a cladistic analysis uses a (ground-based) dinosaur (eg. allosaurus) as the outgroup it makes it look like the flightlessness of the "maniraptors" was inherited from a dinosaur, when in fact they actually descended (in both senses) from a flying primitive bird ancestor.

Sunday, October 4, 2015


The ancestor of primitive birds was a rhamphorhynchoid pterosaur much like Jeholopterus or Pterorhynchus.
The earliest primitive birds were the feathered, flying creatures with long-bony-tails, such as the scansoriopterygids.

The scansoriopterygids would have lived alongside synapsids such as the aquatic Castorocauda and arboreal gliding mammal Volaticotheriumthe rhamphorhynchoid pterosaurs Jeholopterus and Pterorhynchus, as well as a diverse range of insect life (including mayflies and beetles) and several species of salamander.[14][15]
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.

Two other Chinese specimens were reported with integumental covering, coming from the same stratum (the Daohugou Bed) as Jeholopterus. So far we have not had the opportunity to examine this material. The first one is a small unnamed anurognathid with extensive preservation of soft tissue, including fibres that have been interpreted as protofeathers (Ji & Yuan 2002). The published pictures show that the soft tissue interpreted as protofeathers is of the same nature as the pycnofibres of Jeholopterus. 

At least some pterosaurs had hair-like filaments known as pycnofibres on the head and body, similar to, but not homologous (sharing a common structure) with, mammalian hair. Though a fuzzy "integument" (natural covering/outer coat) "was first reported in 1831" by Goldfuss,[29] recent pterosaur finds and the technology for histological and ultraviolet examination of pterosaur specimens have provided incontrovertible proof: pterosaurs had pycnofibre coats. Pycnofibres were not true hair as seen in mammals, but a unique structure that developed a similar appearance. Although, in some cases, actinofibrils (internal structural fibres) in the wing membrane have been mistaken for pycnofibres or true hair, some fossils such as those of Sordes pilosus (which translates as "hairy demon") and Jeholopterus ninchengensis do show the unmistakable imprints of pycnofibres on the head and body, not unlike modern-day bats, another example of convergent evolution.[21] The head-coats do not cover the pterosaur's large jaws in many of the specimens found so far.[29]

A new rhamphorhynchoid [Pterorhynchus] is described with a headcrest that is unprecedented among the long-tailed pterosaurs. The preservation of the headcrest presents significant implications regarding the physical appearance and aerodynamics of all pterosaurs. Also, "hair-like" integumentary structures of this pterosaur are shown to be complex multi-strand structures which presents evidence on the origin of feathers and the possibility of a remarkably early ancestral relationship between pterosaurs and birds.
Pterorhynchus was a genus of rhamphorhynchid "rhamphorhynchoid" pterosaur from the Middle or Late Jurassic-age Daohugou Formation[1] of Inner Mongolia,China.
This type specimen consists of an articulated, nearly complete skeleton with remains of the integument. These included the wing membrane, hair-like structures, a long version of the vane found at the end of "rhamphorhynchoid" tails, and a head crest with both a low bony base and a large keratin extension; the latter feature is unusual in "rhamphorhynchoids" (i.e. basal pterosaurs), the fossils of which do not often show head crests.
The hairs (pycnofibers) were originally described as pinnate, with many strands arising from a single base (calamus), and seen as corresponding to the hypothetical Stage II in the evolution of feathers.
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.

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.
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. Many of its characteristics such as a short neck, short metacarpals and distinctively long fifth pedal digit are characteristic of rhamphorhynchoids. The new species can be further referred to the ‘strange’ short-tailed rhamphorhynchoid family Anurognathidae. It is much more complete than the other known members of the family, namely, Anurognathus from Solnhofen, Germany, Batrachognathus from Karatau, Kazakhstan, and Dendrorhynchoides from Beipiao, Liaoning Province, China. The new pterosaur also shows that the wing membrane is attached to the ankle of the hind limb. The pedal digits are webbed. Furthermore, the “hair” of Jeholopterus bears some resemblance to the hair-like integumental structures of the feathered dinosaur Sinosauropteryxalthough there is yet no direct evidence to argue for or against their homology.

Darwinopterus (meaning "Darwin's wing") is a genus of pterosaur, discovered in China and named after biologist Charles Darwin. Between 30 and 40 fossil specimens have been identified,[1] all collected from the Tiaojishan Formation, which dates to the middle Jurassic period, 161-160.5 Ma ago.[2] The type species, D. modularis, was described in February 2010.[3] D. modularis was the first known pterosaur to display features of both long-tailed ('rhamphorhynchoid') and short-tailed (pterodactyloid) pterosaurs, and was described as a transitional fossil between the two groups.[4] Two additional species, D. linglongtaensis and D. robustodens, were described from the same fossil beds in December 2010 and June 2011, respectively.[5][6]
Darwinopterus, like its closest relatives, is characterized by its unique combination of basal and derived pterosaurian features. While it had a long tail and other features characteristic of the 'rhamphorhynchoids', it also had distinct pterodactyloid features, such as long vertebrae in the neck and a single skull opening in front of the eyes, the nasoantorbital fenestra (in most 'rhamphorhynchoids', the antorbital fenestra and the nasal opening are separate).[5]

Turner et al 2012.

For reference:

The Rhamphorhynchoidea forms one of the two suborders of pterosaurs and represent an evolutionary grade of primitive members of this group of flying reptiles. This suborder is paraphyletic in relation to the Pterodactyloidea, which arose from within the Rhamphorhynchoidea, not from a more distant common ancestor.
Plieninger, 1901
Included groups

Sunday, August 9, 2015

Primitive Birds

Here is a partial list of primitive (feathered, long-bony-tailed) flying and secondarily flightless birds.

Scansoriopterygids (Temporal range: Late Jurassic, 165–156 Ma)
Anchiornis (Temporal range: Late Jurassic, 161–160.5 Ma)
Aurornis (Temporal range: Late Jurassic, 160 Ma)
Xiaotingia (Temporal range: Late Jurassic, 160 Ma)
Oviraptors (secondarily flightless)

Eosinopteryx? (Temporal range: Late Jurassic, 160 Ma)
Pedopenna? (Temporal range: Middle or Late Jurassic, 164 Ma)

The flying primitive (feathered, long-bony-tailed) birds evolved from pterosaurs.
The secondarily flightless primitive birds evolved from the flying primitive birds. 

Monday, July 20, 2015

Basalmost Paraves

There is a set of 4-winged, flying, primitive birds (eg. Anchiornis, Aurornis, Xiaotingia etc.) that at times have been classified as avialans and sometimes as dromaeosaurids. They actually belong to the basalmost Paraves. 
They are the Tetrapterygidae and the Scansoriopterygids.
I suggest that these flying primitive birds evolved from pterosaurs.
Later, some of these primitive birds settled on the ground and became secondarily flightless (eg. eudromaeosaurids, oviraptors etc).

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]

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  is a secondarily flightless member of Paraves.

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.

Sunday, July 5, 2015

Primitive birds flying

Primitive birds (basalmost paraves) flapped their wings and flew using the same set of muscles as their pterosaur ancestors.
At times people have argued that a flying pterosaur would not devolve into a gliding primitive bird. I would agree. But this is not an issue, because the evidence indicates that flying pterosaurs evolved into flying primitive birds, not into gliding primitive birds.


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.

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:


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.


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

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).
But 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 (as in scansoriopterids). 
Note: In the transition from pterosaur to primitive bird, the very long pterosaur digit IV has been replaced with the characteristics of digit III.
Note 2: The dino to bird folk do not consider scansoriopterids to be on the line leading to birds.

Frame shift
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).

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, then the very first paraves were (or were very similar to) the scansoriopterygids. Which have x-2-3-4-x with digit IV being the longest.
Which is consistent with a pterosaur ancestry and contrary to a dino ancestry.

See here for more details:

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:

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.


Oviraptor (secondarily flightless)

Monday, June 22, 2015

Oviraptor Propatagium

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

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
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:

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):
 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

Yi qi

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:


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:
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.


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.


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 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:

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:
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.

If some maniraptorans were
birds, and if birds were not theropods, similarities
between 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. 

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]

Saurischian monophyly and the origin of birds
Jacques Gauthier
Ostrom (1976)

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:

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] 

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. 

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):
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
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)
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)

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

2011 study (Nesbitt)
Includes basal pterosaurs (Dimorphodon, Eudimorphodon).

2012 study (Michael S. Y. Lee):

2012 study (Turner et al)
"One step" Figure 75

2012 study (Senter)

2013 study (Pascal Godefroit):

2013 (Andres)

2014 study (Stephen L. Brusatte)

2001 study (Norell)

2004 study (Renesto)
Includes one pterosaur (Eudimorphodon)


2007 study (Senter)