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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
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
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