Long time readers will know that I contributed a lot to The Speculative Dinosaur Project’s Enantiornithes. Given my recent cladograms (themselves essentially slightly more complex versions of Mortimer 2019’s) I decided to map out Spec’s opposite bird clades given what we now know.
- Overall the original scheme was rather prescient all things considered: a split between a clade composed of Avisauridae (and in some drafts ebergs) and another including most other taxa. In cladograms following Mortimer 2019 this cut in Enantiornithe phylogeny is present; Enantiornis, Gobipteryx and Longipterygidae all form a clade at the exclusion of several other taxa including classic avisaurids (several purported avisaurids like Halimornis and Concornis are basal to this split)
- Twiatiaviformes were originally in the Yahoo group described as both closely related to the False Panha and Allospiziformes, and the Cretaceous taxa Alexornis is given as a potential stem-tweetie. However, Alexornis is now recovered as relatively closer to avisaurids, so either tweeties become part f Avisauriformes or are instead connected to their original relatives, perhaps as extant longipterygids with Gobipipus being an early member.
- Similarly Enabaptiformes (ebergs) have a rather unstable position: either they’re related to Longirostravis (and thus another lineage of surviving longipterygids) or to Yungavolucris (in which case they’re avisaurids).
- Within avisaurids I did make marine taxa based off Halimornis; it’s easy to just say they’re simply avisaurids that converged with Halimornis, though they could easily represent yet another surviving opposite-bird clade.