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Details on Jibeinia



Well, I was in the middle of Pyroraptor's description, but it was horribly destroyed with my hard drive.  I'll write it again soon.  In the meantime, here's information on a bird that's been allied with confuciusornithids, but perhaps incorrectly.
 
Jibeinia Hou 2000
= "Jibeinia" Hou 1997
J. luanhera Hou 2000
= "Jibeinia luanhera" Hou 1997
Etymology- "from the Luanhera(?) river in Northern Hebei", "Yibei" means northern Hebei Province and luanhera is from a river name that originated in Fengning, the regio of it's discovery.
Barremian, Early Cretaceous
Yixian Formation, Hebei, China
holotype- (IVPP collection) (~115 mm) partial skull, lower jaw, (22 mm), five cervical vertebrae (~2.4 mm), four dorsal vertebrae (~2.9 m), dorsal ribs, sacrum, six caudal vertebrae, pygostyle (13 mm), scapula, coracoids, furcula, sternum, sternal ribs?, humerus (23.3 mm), radius (24.2 mm), ulna (24 mm), metacarpal I (2 mm), phalanx I-1 (4 mm), manual ungual I (2.5 mm), metacarpal II (9.3 mm), phalanx II-1 (6 mm), phalanx II-2 (3.7 mm), manual ungual II (2.1 mm), metacarpal III (8.3 mm), phalanx III-1 (1.5 mm), phalanx III-2 (2.9 mm), manual ungual III (1 mm), partial ilium, pubis (21 mm), partial ischium?, femora (22.2 mm), tibiae (28 mm), distal tarsal, tarsometatarsus (16.3 mm), pes, feather impressions
Diagnosis- two non-ungual phalanges in manual digit III.
Description-
If we scale from the femoral length of Confuciusornis, Jibeinia would measure about 115 mm long, not counting tail feathers, which is about half the size of Confuciusornis.  Jibeinia was originally used as the label on a figure of a skeleton described as the Jibei bird in Hou (1997).  This counted as a nomen nudum.  It was later (2000) featured in the Picture Book of Chinese fossil birds in a way which would make it an official taxon.  See Ben Creisler's comments at
http://www.cmnh.org/fun/dinosaur-archive/2000Jul/msg00225.html for details.
The skull is poorly preserved, with the dorsal section missing and everything crushed.  The beak is pointed and the upper jaw has a roughly straight lower margin.  There are at least five teeth in the upper jaw.  The dentary is narrow with at least six teeth.  The teeth lack serrations and have expanded roots.  What may be the articular region of the lower jaw viewed ventrally shows strong medial and lateral processes.
Five or six short cervical vertebrae and four dorsal vertebrae are preserved.  No details are visible.  There are many dorsal ribs preserved and smaller elements that could be uncinate processes or sternal ribs.  No gastralia are present.  At least six, possibly seven, sacral vertebrae are present with sutures still visible between the centra.  There appear to be six free caudal vertebrae and a pygostyle extending the length of about eight centra.  The free caudal vertebrae all have transverse processes and the pygostyle viewed ventrally tapers to a sharp point.
The scapula is narrow and has a triangular anteriorly projecting acromion process.  The distal end appears sharp, but this could be due to breakage.  The coracoid is very large and strut-like with a greatly expanded distal end that broadly contacts the sternum anterolaterally.  The furcula is very narrow and quite possibly V-shaped, it's certainly not as U-shaped as confuciusornithids or Archaeopteryx.  It has an interclavicular angle of 60-70 degrees or so.  The middle section is represented by a dotted line in the figure, which could represent the impression of the bone or hypothetical guesswork.  The dotted line shows a very sharp V-shape without a hypocleidium.  The sternum is nicely preserved and no keel is indicated.  The anterior is convex, with the coracoids attaching more laterally than Confuciusornis.  The lateral processes consist of a long narrow posterolaterally pointing process and a small triangular posteriorly pointing process behind it.  There is a long narrow midline posterior process as well.
The humerus has a much lower deltopectoral crest than confuciusornithids and a prominent posteriorly projecting internal tuberosity.  The distal end is not as expanded as confuciusornithids either.  The radius is slender (~40% of ulnar width) and longer than the humerus by 4% and the ulna is bowed.  The manus is distinctive.  The metacarpals are unfused, metacarpal I is 21% of metacarpal II in length and metacarpal III is 90%.  Metacarpal III is slightly thinner than metacarpal II and bowed laterally.  There are two non-ungual phalanges on digits II and III.  The proximal phalanx on II is longest, while the distal phalanx on III is longest.  There are three unguals, all of which are reduced.  Manual ungual III is smallest, while ungual I is slightly larger than ungual II.
The ilium is poorly prserved and it's structure can not be determined.  The pubis is slender and bowed cranially.  It lacks an obturator notch and has a symphysis over the distal 28%.  The pubic foot is small, triangular and only projects posteriorly.  What may be the plate-like remains of an ischium is present, but is too poorly preserved for comment.
The femur has a declined head and tibial condyle that projects further distally than the fibular condyle.  The tibia is 126% of femoral length and has a fibular crest.  No fibula is preserved.  At least one distal tarsal is preserved.  The metatarsus is non-arctometatarsalian and proximally fused.  Metatarsal II is shortest, while metatarsal IV is slightly shorter than metatarsal III.  Metatarsal IV is not noticeably thinner than the others.  The first digit is retroverted and metatarsal I is placed almost at the distal end of metatarsal II.  On the left pes, pedal ungual II is subequal to ungual III, while on the right it is 30% larger.  There is no heel on phalanx II-2 however and the flexor tubercle on ungual II is not enlarged, so I doubt the digit was hyperextendable.  Compared to Confuciusornis, the hallux is longer (~66% of digit III, opposed to ~50%) and digit IV is shorter, being closer to digit II in length.
There are feathers preserved, including primaries and secondaries.  Also, the photocopy quality is bad, but there appears to be a pair of long narrow tail feathers as in confuciusornithids.
Realtionships-
This is obviously a member of th Pygostylia based on the pygostyle and long strut-like coracoid.  It lacks the confuciusornithid synapomorphies of toothlessness, deltopectoral crest of humerus prominent and subquadrangular and manual ungual II much smaller than other manual unguals.  The only character shared with confuciusornithids is the presence of long, paired tail feathers that may be indicated in the photograph.  Jibeinia seems more derived than confuciusornithids based on the following characters: strong medial and lateral processes of articular, interclavicular angle much less than 90 degrees, manual digit I shorter than metacarpal II, reduced manual unguals, manual phalanx II-1 longer than II-2 and only two phalanges in manual digit III. 
Unfortunately, assignment to the Enantiornithines is uncertain due to the lack of information on Asian species.  Only Spanish and Argentinian species have been subjected to cladistic analyses and many "enantiornithine" characters aren't present in some Chinese species (eg. laterally convex coracoid, reduced metatarsal IV).  In addition, some enantiornithines (Iberomesornis, Cathayornis? caudatus) seem much more basal than others (Neuquenornis, Concornis).  A detailed analysis of known enantiornithines is desperately needed, but is not within the scope of this description.  Jibeinia will however briefly be compared to enantiornithines.
The jaws are toothed as in Cathayornis, Cusprostrisornis, Eoenantiornis, Largirostrornis, Liaoxiornis, Sinornis and the Spanish nestling, unlike Baluochia and Gobipteryx.  Boluochia, Cathayornis yandica, Eoenantiornis, Iberomesornis, Jibeinia, Largirostrornis, Liaoxiornis and Sinornis have a pygostyle, while Cathayornis? caudatus, Longchengornis do not.  The coracoid of Jibeinia is slightly convex laterally.  Concornis, Enantiornis, Eoaluavis, Neuquenornis, the Spanish hatchling and an unnamed French form (Buffetaut 1998) also have laterally convex coracoids, considered a enantiornithine synapomorphy, while Cathayornis? caudatus, Cuspirostrisornis, Iberomesornis and a Mongolian species (Dong 1993) lack this feature.  Jibeinia's furcula has a larger interclavicular angle than Concornis, Eolalulavis, Iberomesornis, Neuquenornis and Sinornis.  The metacarpals of Cathayornis, Concornis, Eolulavis, Largirostrornis, Neuquenornis and a Lecho specimen (Walker 1981) are fused, while Jibeinia, Otogornis, Sinornis and a Mongolian species are unfused.  In Cathayornis, Concornis, Eoalulavis, Longchengornis, Neuquenornis, Sinornis, the Spanish hatchling and a Lecho specimen, the third metacarpal is longer than the second, which is an enantiornithine synapomorphy Jibeinia lacks.  Cathayornis, Concornis, Eoenantiornis and Sinornis only have one phalanx on the third manual digit, which is less than Jibeinia.  Boluochia, Cuspirostrisornis, Jibeinia and Sinornis have a pubic foot, while Cathayornis, Largirostrornis(?) and Longchengornis(?) lack one.  The fourth metatarsal is noticeably thinner than the others in Avisaurus, Boluochia, Concornis, Cuspirostrisornis, Lectavis, Neuquenornis, Soroavisaurus and Yungavolucris, but not in Cathayornis? caudatus, Iberomesornis, Largirostrisornis and Sinornis.
So based on the above information, Jibeinia is more basal than ornithothoracines based on the presence of more than one phalanx on manual digit III and a large interclavicular angle.  It is excluded from the Enantiornithes based on metacarpal II being longer than metacarpal III.  In addition, Jibeinia lacks synapomorphies within the enantiornithines when they can be determined.  I propose that Jibeinia be placed as a pygostylian more derived than confuciusornithids and more basal than ornithothoracines.  This interpretation is open to change as Hou's description is translated and further details are revealed.
 
The figure of the skeleton will be available tomorrow or the next day, so if you would like to see it, just contact me offlist.
 
Mickey Mortimer