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Shenzhouraptor sinensis



  Much thanks to Jerry Harris for getting this paper to me.

Shenzhouraptor sinensis Ji, Ji, You, Zhang, Yuan, Ji, Li & Li,* 2002

  With an impressive authorial list, *Shenzhouraptor* hits the shelves
with a series of features that some have argued makes it look like
*Jeholornis* (Zhou and Zhang, 2002). The skull is unfortunately not very
well preserved and is very crushed. However, the pes is articulated, shows
a heterodactyle arrangement (all toes forward), and the long bony tail is
articulated with a minimum of 23 elements, and room for more.

Abstract:
"This paper deals with an avialae bird from the Early Cretaceous Jiufotang
Formation in Yixian County, western Liaoning, China. This new specimen is
characterized by no teeth in its mouth, the fore-limbs longer than the
hind-limbs, a long tail with more than 20 vertebrae, U-shaped wishbone,
and remiges longer than the total length of ulna and manus. It is sure
that the nre avialae bird is really capavle of flight, representing a
missing link between theropod dinosaurs and birds. It is described in
detail and named as *Shenzhouraptor sinensis* gen. et sp. nov. herein."
[Text is from the paper, transcribed faithfully, including the use of
"avialae" without genitive or capitals.]

Holotype: LPM 0193, complete articulated skull and skeleton with feather
impressions of both wings, and a distal fan of about five feathers per
side at the very end of the tail, not well preserved to show how long they
were beyond the tail tip; the first feathers on the tail start at the 19th
or 20th vertebra, and there is no trace of a more extensive coverage. The
specimen lies on both its side and venter with several elements
overlapping each other: the breast is below the shoulder and vertebrae,
the right hindlimb below the hip and tail for nearly its entire length,
rendering the left hindlimb as the only diagnostic structure. The head and
neck are folded back and lie above the thorax.

Locality, Horizon, and Age: Shenzhou, in Yixian County, Liaoning Province,
People's Republic of China. The specimen is from the well-sampled
Jiufotang Formation, which has been variously dated as latest Jurassic,
earliest Cretaceous, or Aptian in age. No dates are settled.

  The holotype of *Shenzhouraptor* is smaller than that of *Jeholornis*,
but not by much. Elements very between the two, making for interesting
comparisons; comparison of ratios in limbs and gross measurements are also
interesting tools that may diagnose the two taxa. Some examples:

  measurements  Jeholornis      Shenzhouraptor  difference %
Humerus         110mm           79.8mm          28 shorter
Ulna            109mm           83.4mm          24      "
Metacarpal II   47mm            36.7mm          22      "
Femur           75mm            55.4mm          27      "
Tibiotarsus     88mm            68.3mm          23      "
                                          ave = 24.8
  ratios
Hum/Ulna        1.01            0.96            0.95
Ulna/MCII       2.32            2.27            0.98
Fem/Tib         0.85            0.81            0.95
Hum/Fem         1.47            1.44            0.98
                                          ave = 0.956

  The measurements and ratios are relatively stable, and show that
*Shenzhouraptor* averages about one-quarter smaller than *Jeholornis*.
Though Zhou and Zhang (2002) listed a measurement of 47mm for the right
third metatarsal, no complete metatarsal is present in the specimen, IVPP
V13274; given the measurement at its value, the averages relatively are
25.2 and 0.98, and these are not terribly different than the present
values. The ilium is longer in *Shenzhouraptor*, and so are some of the
manus phalanges, than in *Jeholornis*.

Some comments on morphology:

"Internal" refers to the leading edge of the wing, "external" to the
trailing edge, or along the cord.

  The arms are identical between the two forms, which is not surprising,
except the presence of a broad flange on the external first phalanz of
manus digit II, as in *Confuciusornis* and most ornithurne birds, as well
as *Sinornithosaurus*, but not in *Jeholornis*. The scapula is bowed along
its length with the greatest curvature occuring about 2/3s of the way from
the cranial end; there is a tall acrocoracoid process that reaches the
level of the glenoid, but it is not possible to described the element
further, obscured beneath the humerus; the sternum is similarly obscured
beneath the pectoral girdle and ribs. The furcula is short and broad,
roughly U-shaped but the rami are tapered and much more slender than in
*Archaeopteryx* or *Confuciusornis*. Metacarpal I (alular metacarpal) is
only 1/5 that of mcII (major mc), but though the ungual knuckle of the
first digit does not reach the metacarpo-phalangeal joint of the second
digit, the first ungual is largest in the manus. The third metacarpal is
bowed externally and the first two phalanges of the third finger form an
arch externally. The ulna is bowed only at the proximal end, and the
radius is relatively straight; the humerus, however, is broad and massive,
and the deltopectoral crest is more than 1/3 the length of the humerus, at
about 2/5s; the shaft is sigmoid, with a slight inflection internally;
there is a small, triangular adductor crest on the humeral caput.

  The pubis is long and bore a distinct caudal boot, and the ischium was
sabre-shaped with a distinct proximodorsal process, but the rest of the
element is unknown; the ilium has a deep preactuabular ala, unlike
*Jeholornis* where, though obscured beneath the proximal tail, it tapers
distinctly into a triangular rather than rotund shape; the preacetabular
ala is longer than the postacetabular ala by about 150%, and the pubic
peduncle is further ventral than the ischiadic peduncle, the latter which
is short and triangular and the former which is rectangular without a
ventral notch in the margin. It is not possible to determine the degree of
retroversion in the pubic shaft. Toes three and four are closer in length
than three is to two, and the hallux is large. The pes is broad without
the attenuation in the midshaft of the metatarsus seen in many
ornithurines, and they were apparently unfused. The hallux is not
reversed, though this may be an artifact of preservation as in
*Archaeopteryx* and other birds preserved in lagerstätten. The femur is
not bowed cranially, and is roughly the same length as the ilium; the
proximal tarsals appear to be fused to the tibia, forming a tibiotarsus,
and the fibula is present with a long shaft, but wether it is preservation
or natural, it does not appear to contact the ankle, and the calcaneum if
fused to the tibia is not distinct.

  Very little can be said for the head except that it is short, less than
twice the height of the skull in length, and the jaws are said to be
toothless. The orbit appears to be short and about 1/3 the cranial length,
and fairly large antorbital fenestra, and a lare nares with massive
premaxilla. However, these are questionable interpretations drawn from a
photocopied plate. Feathers on the arms are long and taper towards the
third or fourth remex (primary, in this case); the primaries are
well-defined from the secondaries, and the animal likely had a hawk-or
chicken-like wing when spread (short, broad cord, excellent
maneuverability; compare to the wings of *Confuciusornis* which are very
long and tapered as in some shorebirds or fast fliers). Tertials are
present, but these approach the trunk and they are preserved only at the
margin between ribs, elbow, and femur, thus their length or shape cannot
be determined. There appears to be a layer of coverts as the preservation
of the primaries and secondaries cease in a well-defined arch external to
the arm, but carbonaceous traces are present between those and the arm.

Some thoughts:

  All in all, though it seems to be very similar and perhaps congeneric
with *Jeholornis*, the bird is a very well defined example of the phrase
"dino-bird" and "missing-link," and much better visually perhaps than
*Jeholornis* which lacks traces of feathers. Concerns on synonymy are to
be expected, except that even better than the dating difficulties
experienced with the *Epidendrosaurus*/*Scansoriopteryx* issue, both taxa
were described and published in July of 2002, without any further
clarification on the day *Shenzhouraptor* was published. If the two taxa
are synonymous, it suggests that in an animal with an obvious flight
ability the presence of a broad first phalanx of digit II is not entirely
necessary, and can be either convergently developed, or lost.

  * = full names are as follows, so confusion over similar family names
    are avoided: Ji Qiang, Ji Shu'an, You Hailu, Zhang Jianping, Yuan
    Chongxi, Ji Xinxin, Li Jinglu, and Li Yinxian. Note I avoid putting
    in hyphens between syllables in the personal names, which is done
    when the authors transcribe the text themselves or Chinese
    publications (of which this is one) reference the names; hyphens
    are an artifact to avoid syllable confusion in our Romanized
    script.

  References (in alphabetical order):

Ji Q.; Ji S.'a.; You H.; Zhang J.; Yuan C.; Ji X.; Li J.; & Li Y. 2002.
[Discovery of a n avialae bird -- *Shenzhouraptor sinensis* gen. et sp.
nov. -- from China]. _Geological Bulletin of China_ 21 (7): 363-369 (with
2 plates). [in Chinese with English abstract]

Zhou Z. & Zhang F. 2002. A long-tailed, seed-eating bird from the Early
Cretaceous of China. _Nature_ 418: 405-409 (with online supplementary
info).

  Cheers,

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