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New References



Here's some new references I found at the library today.
 
Norell, Clark and Chiappe, 2001. An embryonic oviraptorid (Dinosauria: Theropoda) from the Upper Cretaceous of Mongolia. American Museum Novitates 3315 1-17.
 
An in-depth description of the famous oviraptorid embryo (GI 100/971) reported by Norell et al. (1994).  The cervical ribs are not fused to the vertebrae, unlike adults.  Dorsal pleurocoels are present (at least posteriorly), casting doubt on the assertion pleurocoels start as depressions (discussed earlier with Marjanovic).  The fourth trochantor is present as a small ridge, indicating the depression in Microvenator really is apomorphic and not ontogenetic.  The furcula is already completely fused and resembles Archaeopteryx, confuciusornithids, Bambiraptor and Sinornithosaurus in being broadly U-shaped without a hypocleidium (unlike adult oviraptorids).  The sacral centra are also fused.  The amount of ossification suggests oviraptorids were more precocial that altricial.  The nearly vertical anterior premaxillary margin resembles Oviraptor philoceratops, O. mongoliensis (not called Rinchenia or even "O." mongoliensis) and a new large form more than Ingenia, Conchoraptor and a new small form.  These forms will be described in a forthcoming paper-
Clark, Norell and Barsbold, submitted. Two new oviraptorids (Theropoda: Oviraptorosauria) from the Late Cretaceous Djadokta Formation, Ukhaa Tolgod. Journal of Vertebrate Paleontology.
This will describe the two species mentioned in an abstract from the last SVP meeting-
http://www.cmnh.org/fun/dinosaur-archive/2000Nov/msg00330.html
 
Clarke and Chiappe, 2001. A new carinate bird from the Late Cretaceous of Patagonia (Argentina). American Museum Novitates 3323 1-23.
 
Limenavis Clarke and Chiappe 2001
L. patagonica Clarke and Chiappe 2001
Campanian-Maastrichtian, Late Cretaceous
Allen Formation, Argentina
Holotype- (PVL 4731) distal humerus, proximal and distal ulna, proximal radius, proximal and distal carpometacarpus, partial ulnare, radiale, incomplete phalanx II-1
Comments- This is a derived ornithurine, out of my range of expertise.  The authors assembled a matrix of 54 forelimb characters and 18 other characters (to enforce neornithine monophyly) and got one most parsimonious tree- (Confuciusornis (Enantiornithines (Ichthyornis (Limenavis (Lithornis (Paleognathae, Neognathae)))))).  The Paleognathae was represented by two taxa and the Neognathae by five(?).  Characters supporting the lineages are as follows.
Carinatae (Ichthyornis+)
1- brachial fossa of humerus
2- one or two distodorsal humeral fossae
3- complete proximal and distal metacarpal fusion
4- extensor process on metacarpal I
5- extensor groove on distal tibiotarsus
Limenavis+
- abruptly truncate contact of dorsal trochlear surface of ulna with ulnar shaft
- loss of tubercle adjacent to tendinal groove on distal ulna
Lithornis+
- metacarpal III extends further distally than metacarpal II
Neornithines
- loss of two small fossae on dorsal supracondylar tubercle of distal humerus
- loss of deeply excavated infratrochlear fossa on carpometacarpus
- intermetacarpal process developed as small tuberculum
- distalmost caudal margin of manual phalanx II-1 bowed caudally
- no m. supracoracoideus nerve foramen in coracoid
Most of these characters involve features only seen in ornithurines, so I cannot comment on them much.  However, from what I've seen, some enantiornithines (eg. Cathayornis yandicus) have complete metacarpal fusion.  Also, all enantiornithines and Protopteryx have metacarpal III extending past metacarpal II, making me doubt the validity of this character when used as a Lithornis+Neornithines synapomorphy.  You may remember Apsaravis, an ornithurine from the Late Cretaceous of Mongolia described earlier this year.  It was too late for the authors to include it in their analysis, but it lacks 1 and 5, but has 3 and 4.  This suggests that while 1 and 5 may be carinate characters, 3 and 4 are probably diagnostic of a more inclusive clade (Ornithurae or Euornithes).  I think it would have been interesting to include hesperornithiformes and Patagopteryx while using all available characters.  Now if only we could get Hou's Liaoning ornithurine descriptions translated, someone could put together a great euornithine analysis.
 
Mickey Mortimer