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Details on "Proornis"



"Proornis" Lim vide Pak and Kim 1996
"P. coreae" Lim vide Pak and Kim 1996
Barremian?, Early Cretaceous
Sinuiju series, North Korea
Holotype- skull, cervicals, forelimb, feathers
Diagnosis- metacarpal I longer than Confuciusornis, but shorter than Changchengornis.
Description-
This specimen was discovered in 1993 and first reported with photographs in the popular press in Korea (October 22, 1993 issue of Nodong Sinmum).  It has generally been compared to Archaeopteryx, although Holtz said it could also be a small dromaeosaurid and Chiappe thinks it is dissimilar enough from Archaeopteryx to be in another genus.  Pak and Kim (1996) claimed the bird was named by Lim in 1993, although such a publication has not been located to my knowledge.  This is why the name is in quotations above.  I provisionally assign the Siniuju series to the Barremian based on the presence of the osteoglossomorph fish Lycoptera, also known from the Yixian Formation.
The specimen consists of a skull, some anterior cervicals and a nearly complete forelimb.
The skull is triangular, but further details are difficult to see.  It may be preserved in ventral view, showing the basicranium and parasphenoid rostrum, but this is uncertain.
Similarily, little can be said of the series of cervical vertebrae extending posteriorly from the skull.
The proximal tip of the humerus is missing.  The shaft is straight and the proximal end is expanded posteriorly.  The ulna has a slightly sigmoid posterior edge, while the radius is straight and half of the ulnar width.  The first metacarpal is similar to Archaeopteryx in length, being more elongate than Confuciusornis.  Phalanx I-1 extends past metacarpal II, showing it is less derived than Jibeinia and ornithothoracines.  There is a large manual ungual on the first digit, indicating it is also less derived than Protopteryx.  Phalanx II-1 is flattened and expanded, as in pygostylians, but unlike the slight condition in Archaeopteryx and other maniraptorans.  Phalanx II-2 is slightly longer than II-1, showing "Proornis" to be less derived than Jibeinia and ornithothoracines.  Manual ungual II is much smaller than the other manual unguals, a condition only known in confuciusornithids.  Metacarpal III is slightly short than metacarpal II.  Digit III is about the same length as digit II, which is more primitive than Protopteryx, Jibeinia and ornithothoracines.  There are presumedly three phalanges, of which the last is very elongate.  The ungual is intermediate in size between I and III.
Feather imprints are said to be present, although I cannot see them.
Relationships-
There are a series of characters advocating a position between Archaeopteryx and Protopteryx, as well as a confuciusornithid synapomorphy.
Pygostylia
- phalanx II-1 flattened and expanded
- phalanx II-2 only slightly longer than II-1
Confuciusornithidae
- manual ungual II much smaller than I and III
not Protopteryx + Jibeinia + Ornithothoraces
- large manual ungual I
- digit III not reduced in length compared to II, with large ungual
not Jibeinia + Ornithothoraces
- phalanx I-1 extends past metacarpal II
- phalanx II-2 longer than II-1
The characters above suggest that "Proornis" be referred to the Confuciusornithidae.  Compared to Confuciusornis sactus, metacarpal I and phalanx II-1 are more elongate.  The manus/ulnar ratio is identical (1.43).  The first metacarpal is shorter than Changchengornis, but other comparisons are difficult.  I think "Proornis" should be provisionally valid, until a more in depth analysis is performed.  The identification as a confuciusornithid is consistant with its stratigraphic position.
Those who want a scan of the holotype contact me offlist.
References- Pak and Kim, 1996. Mesozoic Era, in Geology of Korea.
Lee, Yuong-Nam, Kang-Min Yu, and Craig B. Wood. 2001. A review of vertebrate faunas from the Gyeongsang Supergroup (Creataceous) in South Korea. Palaeogeography, Palaeoclimatology, Palaeoecology. 165: 357-373.
 
Mickey Mortimer