Chiappe, 1993. Enantiornithine (Aves) tarsometatarsi from the Cretaceous Lecho Formation of Northwestern Argentina. American Museum Novitates. 3083, 39 pp.

This paper described the Lecho Formation enantiornithine tarsometatarsi which were originally illustrated by Walker (1981). It includes a small cladistic analysis of metatarsal characters within enantiornithines.

Phylogeny

|--Mononykus
|--Patagopteryx
`--Enantiornithes
|--Lectavis
|--Yungavolucris
`--Avisauridae |--Neuquenornis
`--+--Soroavisaurus
`--+--Avisaurus
`--Two Medicine form

Taxon Issues

Two Medicine form- This was later described as Avisaurus gloriae (Varricchio and Chiappe, 1995).

Character Issues

4. Mononykus is coded as lacking an m. tibialis cranialis tubercle on metatarsal II, but this is uncertain as it could be located more distally on the unpreserved midshaft (as in Yungavolucris).

6. Based on the figure in Varricchio and Chiappe (1995), the trochlea of metatarsal IV is no more concave medially in Avisaurus gloriae than in Soroavisaurus. It is thus recoded as plesiomophic.

8. This character (metatarsal III strongly convex dorsally) is coded as absent in Mononykus, yet metatarsal III tapers to end in the distal section of its metatarsus. As the proximalmost area does still overlap with the convex area in avisaurids, the coding is provisionally retained.

9. The trochlea of metatarsal II in Avisaurus archibaldi does not angle medially enough to separate it from that of metatarsal III, unlike A. gloriae and Soroavisaurus. It is thus recoded as plesiomorphic, though this character might be improved with quantified states that would make coding objective.

10. The trochlea of metatarsal II in Mononykus is wider than III or IV, as best visible in ventral view (Perle et al., 1994). It is recoded as apomorphic.

General analysis conclusions- This analysis is mostly flawed by its small size and limitation to metatarsal characters. Also, Mononykus is now recognized to be rather distantly related to enantiornithines, so forms a poor outgroup. However, the characters are described and illustrated in detail, and miscodings are rare. There are only 4 miscodings out of 80 (5%), but the low number of characters gives them the influence to change the cladogram once corrected-

|*-Yungavolucris
|*-Patagopteryx |--Mononykus
`--Enantiornithes
|--Lectavis
`--Avisauridae |--Neuquenornis
|--Avisaurus archibaldi
`--+--Avisaurus gloriae
`--Soroavisaurus

In these trees, Yungavolucris and Patagopteryx can have any position outside Avisauridae.

Phylogenetic conclusions- The table shows the number of extra steps needed to accomodate each rearrangement using Sanz and Bonaparte's original matrix, and his recoded matrix. A negative number means the arrangement is already most parsimonious, but that many steps are needed to undo it.

rearrangement original recoded
(Mononykus,Patagopteryx(Lectavis,Yungavolucris,Neuquenornis,Soroavisaurus,archibaldi,gloriae)) -2 0
(Patagopteryx,Neuquenornis,Soroavisaurus(archibaldi,gloriae)) -1 1

The matrix is too small to confidently reject the monophyly of Enantiornithes or Avisaurus.

Sanz, Chiappe and Buscalioni 1995. The osteology of Concornis lacustris (Aves: Enantiornithes) from the Lower Cretaceous of Spain and a reexamination of its phylogenetic relationships. American Museum Novitates. 3133, 1-23.

This paper redescribed Concornis as an enantiornithine and added it to Chiappe's earlier metatarsal analysis. The tree found was-

|--Mononykus
|--Patagopteryx
`--Enantiornithes
|--Lectavis
|--Yungavolucris `--+--Concornis
`--Avisauridae |--Neuquenornis
`--+--Soroavisaurus
`--+--Avisaurus archibaldi
`--Avisaurus gloriae

General analysis conclusions- No changes were made to the other taxa and Concornis was coded correctly, so 4/90 (4%) of the characters were miscoded. The resulting tree is-

|*-Yungavolucris
|*-Patagopteryx |--Mononykus
`--Enantiornithes
|--Lectavis `--+--Concornis
`--Avisauridae |--Neuquenornis
|--Avisaurus archibaldi
`--+--Avisaurus gloriae
`--Soroavisaurus

This time, Yungavolucris and Patagopteryx can have any position outside Concornis+Avisauridae.

Phylogenetic conclusions-

rearrangement original recoded
(Mononykus,Patagopteryx(Lectavis,Yungavolucris,Neuquenornis,Soroavisaurus,archibaldi,gloriae)) -2 0
(Patagopteryx,Neuquenornis,Soroavisaurus(archibaldi,gloriae)) -1 1

The results are the same as without Concornis.

Experiments with controversial taxa- Adding Confuciusornis as another outgroup might help polarity, as it has several metatarsal characters in common with some enantiornithines and is more closely related to them than Mononykus. Deleting Mononykus also might help the basal resolution, since it is so distantly related. Several enantiornithines have well described metatarsi so could be coded for Chiappe matrix- These include Iberomesornis, Shanweiniao, Boluochia, Eoenantiornis, Gobipteryx, Hebeiornis and Sinornis. In addition, the controversial Vorona and Hollanda have some enantiornithine-like characters and well preserved tarsometatarsi. Several have incomplete codings which overlap other taxa where known- Iberomesornis with Mononykus, Pengornis and Boluochia with Confuciusornis, Eoenantiornis with Yungavolucris and Confuciusornis. Lectavis with Hollanda. Sinornis and Concornis overlap, but each are coded for a few characters unknown in the other so would both still be useful to include. Thus Mononykus, Pengornis, Boluochia, Eoenantiornis and Lectavis are deleted. The new consensus tree (now using Confuciusornis as the outgroup) is-

|--Confuciusornis
|--Boluochia
|--+--Iberomesornis | `--+--Shanweiniao
| `--Patagopteryx |--+--Yungavolucris | `--+--Gobipteryx | `--+--Vorona | `--Longipteryx `--+--Hollanda |*-Sinornis `--+--Concornis
`--Avisauridae |--Neuquenornis
|--Avisaurus archibaldi
`--+--Avisaurus gloriae
`--Soroavisaurus

Sinornis is a member of the Hollanda+Avisauridae clade outside Soroavisaurus+gloriae. If Lectavis is included, it is excluded from the two smaller clades and Concornis+Avisauridae. If Eoenantiornis is included, it is excluded from Iberomesornis+Patagopteryx, Gobipteryx+Vorona or Hollanda+Avisauridae. Pengornis can go anywhere except Iberomesornis+Patagopteryx, Longipteryx+Vorona or Soroavisaurus+gloriae.

Avisauridae is still intact with the same members, though the possibility exists Sinornis belongs as well. Enantiornithine monophyly is not supported, and Hollanda is closer to core enantiornithines than to the included ornithuromorph. Enforcing enantiornithine monophyly only adds one more step though, so was not rejected. In these trees, Lectavis, Vorona and Hollanda have an ambiguous position outside an enantiornithine clade include Iberomesornis, Shanweiniao, Concornis and Avisauridae. A Euenantiornithes sensu Chiappe and Walker (2002) does not take any extra steps, and ends up including Hollanda and Vorona. Constraining a Euornithiformes sensu Kurochkin (1996) of Iberomesornis, Concornis, Sinornis and Boluochia takes two more steps, as does enforcing his Alexornithiformes of Gobipteryx, Neuquenornis, Yungavolucris, Lectavis, Soroavisaurus and Avisaurus, or his Alexornithidae which contains Neuquenornis and Gobipteryx to the exclusion of Avisaurus, Soroavisaurus and his euornithiforms. It takes one more step to join Shanweiniao and Longipteryx in Longipterygidae, as in O'Connor et al. (2009). The broad conclusion is that the analysis is not large enough to confirm or reject any proposed phylogeny.