A tighter focus (5)

Continuing the discussion of the pterosaur lineage leading to Paraves and particularly the hypothesis that Rhamphorhynchoidea developed into Paraves:

Let's see if the time frame works out. 
Rhamphorhynchoidea: 221 - 124 ma
Paraves: 160 - 0 ma

So the timing works out. We see that the Rhamphorhynchoidea were present before (as well as at the same time as) the first members of Paraves. This is consistent with the hypothesis that Paraves developed from members of the Rhamphorhynchoidea. There is no need for any ghost lineage.

We need to remember that the timing does not work out for dinosaurs (see earlier posts). For dinosaurs, members of Paraves existed at the same time as the very earliest dinosaurs.

A tighter focus (4)

Continuing the discussion of the pterosaur lineage leading to Paraves and particularly the hypothesis that Rhamphorhynchoidea developed into Paraves:

Background material:
http://en.wikipedia.org/wiki/Rhamphorhynchoidea

Rhamphorhynchoids Temporal range:Late Triassic–Early Cretaceous,221–124.5Ma

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. Because it is not a completely natural grouping, Rhamphorhynchoidea is not used as a formal group in most scientific literature, though some pterosaur scientists continue to use it as an informal grouping in popular works, such as The Pterosaurs: From Deep Time by David Unwin, and in some formal studies.^[1][2] Ramphorhynchoids were the first pterosaurs to have appeared, in the late Triassic Period (Norian age, about 210 million years ago^[3]). Unlike their descendants the pterodactyloids, most rhamphorhynchoids had teeth and long tails, and most species lacked a bony crest, though several are known to have crests formed from soft tissue like keratin. They were generally small. Nearly all had become extinct by the end of the Jurassic Period, though at least one anurognathid genus, Dendrorhynchoides, persisted to the early Cretaceous. In addition the family Wukongopteridae, which shows a mix of rhamphorynchoid and pterodactyloid features, is known from the Daohugou Beds which are most commonly dated to the Jurassic, but a few studies give a Cretaceous date.^[4][5]

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

ParaviansTemporal range: Late Jurassic–Recent, 160–0Ma

Paraves is a branch-based clade defined to include all dinosaurs [creatures] which are more closely related to birds than to oviraptorosaurs. Paravians comprises two major sub-groups: Avialae, including Jeholornis and flying birds, and Deinonychosauria, which includes the dromaeosaurids and troodontids.
The ancestral paravian is a hypothetical animal; the first common ancestor of birds, dromaeosaurids, and troodontids which was not also ancestral to oviraptorosaurs. Little can be said with certainty about this animal. The work of Turner et al. (2007) suggested that the ancestral paravian could not glide or fly, and that it was most likely small (around 65 centimeters long and 600–700 grams in mass).^[1] But the work of Xu et al. (2003), (2005) and Hu et al. (2009) provide examples of basal and early paravians with four wings, including members of the Avialae (Pedopenna), Dromaeosauridae (Microraptor), and Troodontidae (Anchiornis).^[2][3][4]

A tighter focus (3)

Continuing the discussion of the pterosaur lineage leading to Paraves:

Concerning the pterosaurs we know that there were basal pterosaurs (Rhamphorhynchoidea) and advanced pterosaurs (Pterodactyloidea).

The timing of Paraves is such that theoretically the Paraves could have developed from either the Rhamphorhynchoidea or the Pterodactyloidea. However when we look at physical characteristics, we see that the basal Paraves are much closer to the Rhamphorhynchoidea.

Especially, we can note the long bony tail (and teeth etc) of both basal Paraves and Rhamphorhynchoidea.

So our hypothesis for consideration is that Rhamphorhynchoidea developed into Paraves.
Now we can analyze that idea.

A tighter focus (2)

Continuing the discussion about the ancestry of Paraves:

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

Paraves is a branch-based clade defined to include all dinosaurs which are more closely related to birds than to oviraptorosaurs. Paravians comprises two major sub-groups: Avialae, including Jeholornis and flying birds, and Deinonychosauria, which includes the dromaeosaurids and troodontids.

So what is the ancestry leading to Paraves? The current mainstream thinking is that coelurosaur dinosaurs led to Paraves. But we have already seen that Paraves was already present at the time of the very earliest coelurosaur dinosaurs. (Plus a large number of posts on this site show that birds did not develop from dinosaurs).

So let's look at the pterosaur lineage leading to Paraves, in the next few posts.

A tighter focus

The pterosaur to bird theory contains more than just the idea that birds developed from pterosaurs. It also contains the idea of "parallel lines" of primitive birds.

I will now analyze the pterosaur to bird theory without the idea of the parallel lines. In that case it simplifies to - what is the ancestral line leading to Paraves? 

In the next few posts I will focus on that more tightly focused issue.

The mainstream thinking is that coelurosaur dinosaurs led to Paraves. I have been proposing that pterosaurs led to Paraves. 

Let’s begin with some background. Here is some info on Paraves:

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

“Paraves is a branch-based clade defined to include all dinosaurs [creatures] which are more closely related to birds than to oviraptorosaurs. Paravians comprises two major sub-groups: Avialae, including Jeholornis and flying birds, and Deinonychosauria, which includes the dromaeosaurids and troodontids.

The ancestral paravian is a hypothetical animal; the first common ancestor of birds, dromaeosaurids, and troodontids which was not also ancestral to oviraptorosaurs. Little can be said with certainty about this animal. The work of Turner et al. (2007) suggested that the ancestral paravian could not glide or fly, and that it was most likely small (around 65 centimeters long and 600–700 grams in mass).^[1] But the work of Xu et al. (2003), (2005) and Hu et al. (2009) provide examples of basal and early paravians with four wings, including members of the Avialae (Pedopenna), Dromaeosauridae (Microraptor), and Troodontidae (Anchiornis).^[2][3][4]

The name Paraves was coined by Paul Sereno in 1997.^[5] The clade was defined by Sereno in 1998 as a branch-based clade containing all Maniraptora [creatures] closer to Neornithes (which includes all the birds living in the world today) than to Oviraptor.^[6]”

I have struck through the words “dinosaurs” and “maniraptora” because those labels add the additional ASSUMPTION of a dinosaur ancestry. And the actual definition stands up completely and accurately without that assumption. Nothing is lost in terms of the actual creatures involved.

Paraves still comprises the two major sub-groups: Avialae*, including Jeholornis and flying birds, and Deinonychosauria, which includes the dromaeosaurids and troodontids

  

* Note that “Avialae” also includes Scansoriopterygidae.

Significant separation

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

The two most significant separations between subgroups are those between the Paraves and other coelurosaurs and between the paravian clades Avialae and Deinonychosauria.

The reason that there is a "significant separation" between Paraves and coelurosaur dinosaurs is because they are not related. 

Paraves existed at the same time as the earliest dinosaurs

Note that Eumaniraptora (Paraves) existed at the same time as the earliest dinosaurs. Paraves were primitive birds with pennaceous feathers. Paraves could not have descended from dinosaurs.
(Click to enlarge).

Note Eumaniraptora in the chart above. It is on the far right. You can see that it extends back to the time of the very earliest found maniraptor dinosaurs.

Rhamphorhynchoidea and Paraves

There are strong similarities between Rhamphorhynchoidea and Paraves.

RHAMPHORHYNCHOIDEA

http://australianmuseum.net.au/image/Pterosaur-Rhamphorhynchus-muensteri
Pterosaur, Rhamphorhynchus muensteri. Late Jurassic, 150–140 million years ago.

http://en.wikipedia.org/wiki/Rhamphorhynchoidea
Artist's impression of Rhamphorhynchus muensteri

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

Specimen with tail vane, Royal Ontario Museum

PARAVES

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

Velociraptor mongoliensis restored with large wing feathers, as evidenced by fossil quill knobs

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

Fossil specimen of a Microraptor, with white arrows pointing at preserved feathers

http://www.futurity.org/science-technology/four-winged-dino-lured-mates-with-long-tail/
Microraptor, a four-winged dinosaur, had an iridescent sheen and a narrow tail adorned with streamer feathers.

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

Fossil specimen of J. prima (IVPP V13550)

Here is the mainstream thinking about the lineage leading to Paraves. This is based on a purported dinosaur ancestry. I am presenting a different idea. That Paraves developed from pterosaurs.

http://www.geoforum.fr/topic/17907-ces-dinosaures-nommes-oiseaux/page-4

http://www.nature.com/ncomms/journal/v4/n1/fig_tab/ncomms2389_F3.html

http://www.geol.umd.edu/~tholtz/G104/lectures/104coelur.html

Pterosaurs taken as birds

Here are pterosaurs that have been taken as birds. This again shows that pterosaurs and primitive birds are very similar.

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

Eurolimnornis is the name given to a monotypic genus of pterosaurs from the Early Cretaceous. The only known species E. corneti probably was originally identified as a primitive but essentially modern bird (or even as an early neognathe ancestral to the grebes),[1] although alternative theories later suggested that it was a non-avialan theropod or pterosaur.[2] The identification as a pterosaur was supported by a re-evaluation of the fossil remains published in 2012.[3]
The holotype and only material known to date (MTCO-P 7896) is a distal fragment of the right humerus, which was at first ascribed to the same species as the specimen of Palaeocursornis corneti, a possible synonym also originally identified as a bird.[4][3]

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

Palaeocursornis is a monotypic genus of pterosaurs. The only known species, P. corneti, was described in 1984 based on a single bone (MTCO-P 1637) interpreted as the distal part of a left femur, found in Early Cretaceous (Berriasian rocks (dating to around 143 mya) from a mine at Cornet near Oradea in northwestern Romania. It was initially assumed to be a flightless paleognathe bird, possibly a ratite, and later as a more primitive ornithuromorph or non-avialan theropod (Benton et al., 1997). However, re-evaluation of the specimen suggested that it was not a femur at all, but the upper arm bone (humerus) of a pterodactyloid pterosaur similar to Azhdarcho.^[1]

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

Piksi is a genus of pterosaurs containing the single species Piksi barbarulna (meaning "strange elbowed big bird ", from Blackfoot piksi, "big bird" or, specifically, "chicken" and Latin barbarus "strange, outlandish" + ulna, elbow^[1]). It lived roughly 75 million years ago in what is now Montana, USA. Known from parts of a right wing – the humerus, ulna and radius bones – the only specimens found so far are housed in the Museum of the Rockies(collection number MOR 1113). The genus Piksi is monotypic at present.

The bones are fragmentary and represent roughly the elbow area. Comparing the fossils' size to the wing bones of other ground birds, P. barbarulna seems to have been about as large as a Common Pheasant, i.e. some 15 in (35–40 cm) long excluding tail, and with a wingspan of perhaps 30 in (80 cm) or somewhat less. It would thus have weighed maybe 1 – 2 pounds (some 500 g – 1 kg).^[2]The original description of the fossils found its affinities unresolvable except that it was probably an ornithothoracine bird. Agnolin and Varricchio (2012) reinterpreted Piksi barbarulna as a pterosaur rather than a bird, most likely a member of Ornithocheiroidea.^[3]

Original article::
http://journals2.scholarsportal.info/details.xqy?uri=/12809659/v34i0004/883_sropbvaprtab.xml

Varricchio (2002 ) described some forelimb bones from the Late Cretaceous (Campanian) Two Medicine Formation, Glacier County, Montana (USA), as the holotype of Piksi barbarulna, a supposed ornithothoracine bird. However reevaluation of Piksi Varricchio, 2002 instead recognizes this genus as belonging to Pterosauria Kaup, 1834 and not Aves Linnaeus, 1758. Piksi exhibits the following derived humeral traits of pterosaurs: 1) very large ectepicondyle; 2) large trochlea; 3) with a deep, wide and poorly deliminated brachial depression that is proximodistally extended; 4) a wide and deep olecranal fossa not marked dorsally by a ridge; and 5) lacking a distal depression of the groove for the m. humerotricipitalis. Moreover, the putative Early Cretaceous birds Eurolimnornis Jurcsák & Kessler, 1986 and Palaeocursornis Jurcsák & Kessler, 1986 , based on distal humeri, are also regarded as pterosaurs. The record of Piksi constitutes an important addition to the Latest Cretaceous pterosaurian record.

Flight Stroke

http://www.jstor.org/pss/2400656

"An analysis of the structure and kinematics of the forelimbs and hindlimbs of pterosaurs, and functional analogy with recent and fossil vertebrates, supports a reappraisal of the locomotory abilities of pterosaurs. A hypothesis of structural, aerodynamic, and evolutionary differences distinguishing vertebrate gliders from fliers is proposed; pterosaurs fit all the criteria of fliers but none pertaining to gliders. The kinematics of the reconstructed pterosaur flight stroke reveal a down-and-forward component found also in birds and bats; structural features of the shoulder girdle and sternum unique to pterosaurs may be explained in light of this motion. The recovery stroke of flight was accomplished, in birdlike fashion, by a functional reversal of the action of the M. supracoracoideus by the pronounced enlargement of the acrocoracoid process, which acted as a pulley."

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

The supracoracoideus works using a pulley like system to lift the wing while the pectorals provide the powerful downstroke

Pelvic Bones Summary

Here is a summary of the material about pterosaur pelvic bones.

PELVIC BONES

http://icb.oxfordjournals.org/cgi/content/full/40/1/87#SEC3

"Several aspects of the pelvic girdle suggest that pterosaurs were specialized for pelvic aspiration during flight. As in birds, the three pelvic bones of pterosaurs were solidly fused into a single unit (Fig. 9), and an increased number of dorsal vertebrae were incorporated into the sacrum (3 to 5 in Rhamphorhynchusand as many as 10 in Pteranodon) (Wellnhofer, 1978, 1987)"

http://pterosaurnet.blogspot.ca/2010/05/pelvic-bones.html

http://pterosaurnet.blogspot.ca/2010/05/pubic-bones.html

http://pterosaurnet.blogspot.ca/2012/12/no-connection-between-dinosaurs-and.html

ACETABULUM/FEMUR ARTICULATION

http://pterosaurnet.blogspot.ca/2010/05/acetabulum.html

http://books.google.ca/books?id=idta6AVV-tIC&pg=PA10&lpg=PA10&dq=Unwin+%281988%29+,+pterosaurs+have+an+imperforate+acetabulum,&source=bl&ots=2E_W7T0hQs&sig=sEqzrX-ZuACLWeCHl23YaV9z9gc&hl=en&ei=2TvoS6W2B4bGlQfmxfnXAw&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCAQ6AEwAg#v=onepage&q=Unwin%20(1988)%20%2C%20pterosaurs%20have%20an%20imperforate%20acetabulum%2C&f=false

See page 10

"The hip joint of pterosaurs is more mobile and profoundly different from that of theropods but is reminiscent of that of mammals, especially of humans, allowing a wide range of adduction and abduction in the vertical plane."

"The femoral component [of the Anhanguera pterosaur femur]  is a well defined spherical head which is distinctly separated from the shaft by a narrow non-articular neck at an obtuse angle of 160 degrees. The head forms a ball and socket joint with the close-fitting, shallow and imperforate acetabulum." 

"In theropods [dinosaurs], the femoral component is cylindrical without any distinctive head and neck. It projects medially at a right angle [90 degrees] from the shaft and fits into a perforated acetabulum of up to 1.5 times its diameter. As a result, the hip joint is stable and fully congruent during parasagittal motion, permitting a wide range of flexion and extension but very little abduction and adduction."

http://pterosaurheresies.wordpress.com/2011/10/14/pterosaur-femur-time/
Two pterodactylid pterosaurs:

http://www.lusofossils.com/verte.html
Dinosaur:

http://www.innerbird.com/pelvic_girdle/pelvic_girdle.html

Birds are the only living vertebrate whose hind limb includes three long bones in sequence. The innermost of the two long bones are similar to those found in most vertebrates. At the hip, the femur, is held more or less parallel to the ground and is bound to the hipbones by the massive thigh muscles. In effect, the femur is an addition to the hipbones and its rotation contributes little to the length of the bird’s stride. 

http://www.sciencedaily.com/releases/2009/06/090609092055.htm

During walking and running in birds, hindlimb movement is generated primarily at the knee and ankle joints; in humans, movement occurs at the knee, ankle and hip joints. The bird's thigh does not move substantially from its nearly horizontal position where it provides rigid lateral support to the thin walled air-sacs of the respiratory system. (Credit: Image courtesy of Oregon State University).

Note the pterosaur prepubis:
http://pterosaurheresies.wordpress.com/2011/11/06/whats-with-that-deep-prepubis/

The “dark wing” specimen of Rhamphorhynchus muensteri JME SOS 4785 (Tischlinger and Frey 2002) has one overlooked oddity worth mentioning. It had an incredibly deep prepubis (Figure 1.)

http://archosaurmusings.wordpress.com/2009/12/24/back-to-that-pterosaur-sacrum-pelvis

So much so normal, but pterosaurs also have a fourth pelvic bone in the form of the pre-pubis.

The Auk 124(3):789–805, 2007

THE ANTITROCHANTER OF BIRDS: FORM AND FUNCTION IN BALANCE

Fritz Hertel1,3 and Kenneth E. Campbell, Jr.2

Abstract.—The antitrochanter is a uniquely avian osteological feature of the
pelvis that is located lateral to the postero-dorsal rim of the acetabulum. This feature
makes the avian hip joint unique among all vertebrates, living and fossil, in
that a significant portion of the femoral–pelvic articulation is located outside of the
acetabulum. This additional acetabular articulation occurs between the neck of the
femur and the antitrochanter, and operates as a hinge joint or ginglymus. It is complementary
to the articulation of the head of the femur with the acetabulum, which
is a pivot joint or trochoides. The size, location, and spatial orientation of the antitrochanter
were determined for 77 species of birds representing a variety of hindlimb
functions (e.g., highly cursorial, vertical clinging, foot-propelled diving) and spanning
a wide range of body sizes (swifts to rheas). The area of the antitrochanter is
a good predictor of body mass in birds; its position and orientation are reasonably
consistent within hindlimb morphofunctional groups, but not among all birds. The
antitrochanter serves as a brace to prevent abduction of the hindlimb and to absorb
stresses that would otherwise be placed on the head of the femur during bipedal
locomotion. The drum-in-trough-like form of the antitrochanter–femur articulation
tends to assist in the transfer of long-axis rotational movements of the femur to the
pelvis. The avian antitrochanter is a derived feature of birds that evolved as an aid
in maintaining balance during bipedal terrestrial locomotion. 

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

Pterosaurs' hip sockets are oriented facing slightly upwards, and the head of the femur (thigh bone) is only moderately inward facing, suggesting that pterosaurs had a semi-erect stance. It would have been possible to lift the thigh into a horizontal position during flight as gliding lizards do.

Pteroid Bone and Alula Summary

Here is a summary of material about the pterosaur pteroid bone and the bird alula.

PTEROID BONE

I am proposing that the pteroid bone is the pterosaur thumb and it developed into the bird alula.
The pteroid articulates with the thumb metacarpal. The thumb metacarpal has been incorrectly referred to as the medial carpal (Padian 1984), and has also been incorrectly termed the distal lateral (Wellnhofer 1985), or pre-axial carpal 

When you study the drawings and pictures you see that the "distal carpal" (syncarpal)  is  the same shape as all 4 distal carpals fused. When the distal syncarpal is seen to include all 4 distal carpals, then we see that the bone that articulates with it (the metacarpal) is shaped like a metacarpal (and not a carpal).
And this arrangement of carpal (syncarpal), metacarpal and phalanx (pteroid) is of course the usual pattern.


Related links:

http://pterosaurnet.blogspot.ca/2010/05/carpus-deum.html

The medial carpal [thumb metacarpal] bears a deep concave fovea that opens anteriorly, ventrally and somewhat medially, within which the pteroid articulates (figure 1b)."

http://pterosaurnet.blogspot.ca/2010/12/pterosaur-wrist-3.html
Here the thumb metacarpal is mislabeled as "preaxial carpal" (pc).

http://pterosaurnet.blogspot.ca/2010/12/more-on-pterosaur-wrist.html
Here the thumb metacarpal is mislabeled as "lateral carpal":

http://pterosaurnet.blogspot.ca/2010/12/pterosaur-wrist-5.html

http://pterosaurnet.blogspot.ca/2010/12/pterosaur-wrist-4.html
Here the thumb metacarpal is mislabeled "preaxial carpal" (pc).

http://pterosaurnet.blogspot.ca/2010/12/additional-fossils.html

http://pterosaurnet.blogspot.ca/2010/12/with-new-understanding-of-sesamoid-bone.html

http://pterosaurnet.blogspot.ca/2010/11/analyzing-primitive-bird-hand.html

Here is a quote from Harry Seeley:

http://www.freefictionbooks.org/books/d/23536-dragons-of-the-air-by-h-g-seeley?start=49

"In the German fossils the pteroid articulated with a separate carpal or metacarpal bone, placed on the side of the arm adjacent to the radius, and the radius is always more inward than the ulna. If the view suggested by Von Meyer is adopted, this bone [pteroid] would be a first digit extending outward and backward towards the humerus. That view was adopted by Professor Marsh. It involves the interpretation of what has been termed the lateral carpal as the first metacarpal bone, which would be as short as that of a bird, but turned in the opposite direction backward. The first digit would then only carry one phalange, and would not terminate in a claw, but lie in the line of the tendon which supports the anterior wing membrane of a bird."

http://pterosaurnet.blogspot.ca/2011/10/seriema.html

http://pterosaurnet.blogspot.ca/2010/05/bird-and-pterosaur-carpus-2.html

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

"The wing of a modern bird, for example, has only two remaining carpals; the radiale (the scaphoid of mammals) and a bone formed from the fusion of four of the distal carpals.^[14]"

http://pterosaurnet.blogspot.ca/2012/12/another-pterosaur-to-bird-theorist.html

http://pterosaurnet.blogspot.ca/2011/11/uniqueness.html

http://pterosaurnet.blogspot.ca/2010/05/continued-2.html

http://www.jstor.org/pss/50448

"The interpretation by Goldfuss (1831) of the pteroid as the first digit, or thumb, and thus the wing-finger as the fifth digit, sparked off a protracted debate"

and

 "The nature of the pteroid, a rod-like bone projecting from the carpus in pterosaurs, has long been disputed. Three lines of evidence, morphological, developmental and histological, indicate that the pteroid is a true bone, rather than ossified cartilage. The origin of the pteroid is unclear: it may be a modified carpal, the first metacarpal, or a neomorph" [or thumb]. 

http://bigcat.fhsu.edu/biology/cbennett/flotsam/Bennett-2007-Pteroid.pdf

 Goldfuss  (1831) suggested  that  the pteroid represented a vestigial  Digit  I, the small fingers Digits  II–V, and the wing-finger Digit V.Although Owen  (1869) sided with Cuvier,  most authors (Wagner,  1837; Fraas, 1878; Marsh,  1882; Zittel,  1882; Williston, 1903) sided with Goldfuss, until Williston (1904,1911) and  Plieninger  (1906) presented convincing  arguments that  the phalangeal formula  of pterosaurs, 2-3-4-4-x, is essentially  un-changed  from their  non-volant ancestors  except  for the possible loss of an ungual on the wingfinger. That view has been accepted by almost  all authors ever since (e.g., Romer,  1956; Kuhn, 1967; Wellnhofer, 1978, 1991a), although Unwin and colleagues  (1996) resurrected the  Goldfussian view as a viable alternative to the Cuvierian without  actually  supporting it."

http://pterosaurnet.blogspot.ca/2012/12/no-connection-between-dinosaurs-and.html

http://pterosaurheresies.wordpress.com/2011/09/08/the-prepubis-of-pterosaurs-and-fenestrasaurs/

"Only a few years ago it seemed that pterosaurs had three bones not found in other tetrapods: the prepubis, the pteroid and the preaxial carpal. Now these bones have been found in three fenestrasaur sister taxa, with Peters (2009) reporting on the latter two."

ALULA

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

The alula, or bastard wing, is a small projection on the anterior edge of the wing of modern (and some ancient) birds. The word is Latin and means "winglet"; it is the diminutive of ala, meaning "wing". The alula is the freely moving first digit, a bird's "thumb," and is typically covered with three to five small feathers, with the exact number depending on thespecies. Like the larger flight feathers found on the wing's trailing edge, these alula feathers are asymmetrical, with the shaft running closer to anterior edge.