Tuesday, January 12, 2016

How not to redefine Ornithuromorpha

The answer is "any possible way."  As in, DON'T redefine Ornithuromorpha Chiappe et al. 1999, which has until now only been given two definitions, both node-based.  There's Chiappe's (2001) original "Patagopteryx + Vorona + Ornithurae" and his later (2002) more refined "Patagopteryx + Ornithurae", both based on the same topology, with a trichotomy between Patagopteryx, Vorona and Ornithurae.  Ornithurae in this case is Chiappe's version which was Hesperornis plus modern birds.

Yet in the description of their new bird Dingornis [edit] Dingavis longimaxilla (first mentioned in Wang et al., 2015), O'Connor et al. (2016) redefine Ornithuromorpha to be stem-based.  Their Ornithuromorpha is "The first ancestor of Neornithes that is not also an ancestor of the Enantiornithes, and all of its descendants."

Holotype of Dingavis longimaxilla IVPP V20284 (scale = 20 mm; after O'Connor et al., 2016).

First of all, will everyone PLEASE start paying attention to Phylocode Article 11.1- "All specifiers used in node-based and branch-based definitions of clade names, and one of the specifiers used in apomorphy-based definitions of clade names, are species or specimens."  Chiappe had the excuse that he was working over a decade ago.  But in 2016 that doesn't cut it.  And it's SO easy!  Just say "Passer domesticus < - Enantiornis leali".  Done!

Second, O'Connor et al.'s excuse is that "Although the proposed definition does not strictly equate with the published node-based definition, it does provide a formal definition for the current widespread usage of this term in most recent literature (Bell et al. 2010; O’Connor et al. 2010; S. Zhou et al. 2013a; M. Wang et al. 2015)."  Let's review those...
- Bell et al. (2010) in their description of Hollanda have Patagopteryx as the most basal taxon closer to modern birds than enantiornithines, so have no need for a different definition than Chiappe's and don't explicitly use one either.
- O'Connor et al. (2010) in their description of Longicrusavis have the same situation.
- Zhou et al. (2013) in their description of new Archaeorhynchus specimens don't even show a topology or mention Patagopteryx.  Notably, Zhou and Zhang (2006) in the original description of Archaeorhynchus just deleted Patagopteryx from the matrix they used without justification.  Why do you hate Patagopteryx so much, Zhou?
- Wang et al. (2015) in their description of new Gansus material do indeed place Ornithuromorpha in the wrong position, as they have Archaeorhynchus and Jianchangornis further from modern birds than Patagopteryx or Vorona, yet include them among Ornithuromorpha.  Note O'Connor was second author here.
So only one paper listed actually uses Ornithuromorpha as if it were a stem, and that shared a coauthor.  Hardly a convincing case that the usage is "widespread."  Sure there are other papers that use it this way, but almost all have O'Connor as a coauthor.  You don't get to use a name incorrectly tens of times and then say "looks like all the papers are using it this way, we better change it."

Third, by redefining names you're countering the entire point of phylogenetic nomenclature.  The beauty of the system is that regardless of your topology, you can apply clade names because their definitions stay constant.  Just find Passer and Ornithomimus in your tree and you'll always know where Maniraptora goes.  But if you pull a Sereno and declare Maniraptora to be "Oviraptor + Passer" instead, then your concept is no longer the same.  Ditto for Ornithuromorpha.

"Passer domesticus < - Enantiornis leali" is certainly a clade that deserves a name, but it's not the more exclusive Ornithuromorpha.  We didn't call the clade Ornithurae just because the BANDits got it wrong so often in the 90s, and we should aim to be better this time as well.

As an aside,  O'Connor et al. state "Although we do not consider [Gansus zheni] to be referable to Gansus, previously only known from the Xiagou Formation (You et al. 2006), we also recognize minor differences that suggest they are not referable to Iteravis huchzermeyeri."  After my in depth study, I'm skeptical.  Notably, O'Connor et al. did not add zheni to their matrix, although Iteravis emerged in a polytomy with Gansus
Is Dingavis from the same locality another synonym of Iteravis?  While it does seem to share the ventrally concave ischium with small mid dorsal process (also in Piscivoravis, Yanornis and Gansus), pedal digit IV is shorter (89% of III excluding unguals; compared to 99-110% in Iteravis), the ectethmoid (lacrimal of O'Connor et al.) is more acute, the carpometacarpus more elongated, and phalanx III-1 lacks the lateral process.  So offhand, I'd agree they're distinct.

References- Chiappe, 2001. Phylogenetic relationships among basal birds. In Gauthier and Gall (eds). New perspectives on the origin and early evolution of birds: Proceedings of the international symposium in honor of John H. Ostrom. Peabody Museum of Natural History. 125-139.

Chiappe, 2002. Basal bird phylogeny: Problems and solutions. In Chiappe and Witmer (eds). Mesozoic birds: Above the heads of dinosaurs. University of California Press. 448-472.

Zhou and Zhang, 2006. A beaked basal ornithurine bird (Aves, Ornithurae) from the Lower Cretaceous of China. Zoologica Scripta. 35, 363-373.

Bell, Chiappe, Erickson, Suzuki, Watabe, Barsbold and Tsogtbaatar, 2010. Description and ecologic analysis of Hollanda luceria, a Late Cretaceous bird from the Gobi Desert (Mongolia). Cretaceous Research. 31(1), 16-26.

O’Connor, Gao and Chiappe, 2010. A new ornithuromorph (Aves: Ornithothoraces) bird from the Jehol Group indicative of higher-level diversity. Journal of Vertebrate Paleontology. 30(2), 311-321.

Zhou, Zhou and O'Connor, 2013. Anatomy of the basal ornithuromorph bird Archaeorhynchus spathula from the Early Cretaceous of Liaoning, China. Journal of Vertebrate Paleontology. 33(1), 141-152.

Wang, Clarke and Huang, 2015. Ornithurine bird from the Early Cretaceous of China provide new evidence for the timing and pattern of the evolution of avian skull. Journal of Vertebrate Paleontology. Program and Abstracts 2015, 233.

Wang, O'Connor, Li and You, 2015. New information on postcranial skeleton of the Early Cretaceous Gansus yumenensis (Aves: Ornithuromorpha), Historical Biology. DOI: 10.1080/08912963.2015.1006217

O'Connor, Wang and Hu, 2016. A new ornithuromorph (Aves) with an elongate rostrum from the Jehol Biota, and the early evolution of rostralization in birds. Journal of Systematic Palaeontology. DOI: 10.1080/14772019.2015.1129518


  1. "Passer domesticus < - Enantiornis leali" is certainly a clade that deserves a name

    It has a name: Euornithes Sereno, 1998.

    Unfortunately, Sereno published this long paper in N. Jb. Geol. Paläont. Abh., which appears to be next to unavailable in the US on dead trees and has only existed as pdfs for a few years now. This must be why it's almost never (though not literally never) been used in the literature since then or by other people; it's also why Jingmai continues not to use it even though I told her about it at least twice (when peer-reviewing manuscripts of hers).

    Of course it's in TaxonSearch...

    1. As I said on Facebook- "Euornithes was defined that way by Sereno (1998), but was first defined by Sanz and Buscalioni (1992) as (Iberomesornis + Ornithurae) and originally erected by Stejneger (1885) for what we call Neognathae minus penguins. So I'm not comfortable with its use for the (Passer <- Enantiornis) clade that's different than both."

      You replied with- "Meh. Euornithes sensu Sereno has been used a few times; Euornithes sensu Sanz & Buscalioni has never been used again, and Euornithes sensu Stejneger is just ancient history, like those versions of Tetrapoda that refer to those lizards which haven't lost any limbs."

      I'd just prefer to use a name with less baggage. Indeed, TaxonSearch notes that Cope (1889) and Dementjev (1940) both also proposed Euornithes for other groups of birds. Sereno's definition is also inferior in using Sinornis instead of the eponym of Enantiornithes, but it is Sereno after all...

    2. N. Jb. Geol. Paläont. Abh. was a reasonably well-known journal that published lots of dinosaur papers in the 1990s and into the early 2000s. It's one of the journals I used to photocopy a lot on my trips to the University of Toronto. I didn't know it was .pdf only now, but that might explain why it is seen as obscure, since the way I accessed it in the past (walking into the library of an institution I had no affiliation with) might not work now.

    3. I'd just prefer to use a name with less baggage.

      Those names have been too long forgotten to put any baggage on their more recent homonym. It's like Tetrapoda or Angiospermae in this respect.

      I didn't know it was .pdf only now

      Oops, sorry for my ambiguous wording – it's not at all pdf-only; what I was trying to say is that there weren't any pdfs of it until recently. It wasn't available online at all, only on dead trees, so either your library carried it (and you actually went there) or you couldn't get it.

  2. Sereno, P. C. (1998) A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen 210:41–83.