Chongmingia: no longer an enigma bird

Wang et al. 2016
reported on a head-less, ‘tail-less’ basal bird fossil, which they named Chongmingia (Fig. 1).

Unfortunately the team had some difficulty nesting Chongmingia.
They reported: “For the first analysis using the coelurosaurian matrix, the analysis produced 630 most parsimonious trees of 4523 steps (Consistency index = 0.266, Retention index = 0.578). The strict consensus tree placed Chongmingia within basal Avialae, and Chongmingia is the sister taxon of Ornithothoraces. For the second analysis focusing on phylogeny of Mesozoic birds, the analysis produced four most parsimonious trees of 1009 steps. The strict consensus tree places Chongmingia as the sister to all avialans except for Archaeopteryx, and thus Chongmingia represents the most primitive bird from the Jehol Biota uncovered to date and one of the most primitive Cretaceous birds known. However, this phylogenetic hypothesis was weakly supported by both Bremer and Bootstrap values.”

Unfortunately the team did not use several Solnhofen birds 
in their phylogenetic analysis. Perhaps if they did so, like the large reptile tree (LRT, 998 taxa) does, then they might have recovered a single tree in which Chongmingia nests within basal Enantiornithes in the LRT.

I was able to see in the published photo of Chongmingia

1. a small string of diminishing caudal vertebrae
2. the dorsal portion of the scapula
3. the distinction between the scapula and coracoid (they thought it was fused)
4. Manual digit 1 (beneath the metacarpus)

Such a small tail
like the similarly short-changed Protopteryx, would not have accommodated many rectrices (tail feathers). So Chongmingia might not have been as great a flyer as some of its relatives with pygostyles. Several other enantiornithes likewise do not preserve a tail of any sort.

References
Wang M, Wang X, Wang Y and  Zhou Z 2016. A new basal bird from China with implications for morphological diversity in early birds. Nature Scientific Reports 6, art. 19700, 2016.

wiki/Chongmingia