[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: [dinosaur] Brontornis (giant flightless Miocene bird) belongs to Galloanserae (free pdf)



We modified the Worthy et al. dataset for the description of Asteriornis, and as our version includes potentially key taxa such as Conflicto, Gallinuloides, and of course Asteriornis, it might be a useful test for this... For the published version of our analysis, we removed the flightless neognaths, because they seemed to be returning probable artifactual results and weren't the focus of our study, but it was simple enough for me to reintroduce them to the dataset, conservatively score them for the few characters we added, and implement Agnolin's scoring changes.

When analyzed in TNT with the extant taxa (and the moa) under a molecular scaffold, I get:

-With all taxa included: Brontornis, Gastornis, dromornithids, and Patagornis form a flightless neoavian clade most closely related to Cariama... (Right, this was why we took them out...) Brontornis is most closely related to Gastornis in this topology.

-With flightless neognaths except Brontornis excluded: Brontornis is sister to Cariama.

-With flightless neognaths except the two Gastornis species excluded: Gastornis is either a stem-anseriform (forming a clade with Vegavis)... or a neoavian outside the a clade formed by the extant neoavians sampled (in those trees, Vegavis, Anatalavis + Conflicto, and presbyornithids form a clade of stem anseriforms).

-With flightless neognaths except dromornithids excluded: dromornithids are... stem paleognaths, hmm... Lithornithids become crown paleognaths (sister to Tinamus), and Conflicto hops over to the galliform stem?!

-Same as previous but with flightless paleognaths also excluded: dromornithids are stem anseriforms, sometimes forming a clade with Vegavis. (Other times, Vegavis is a stem bird, as in our published topology.)

-With flightless neognaths except Patagornis excluded: Patagornis is sister to Cariama.

-With flightless neognaths except Sylviornis and Megavitiornis excluded: The two form a clade of stem galliforms, crownward of Gallinuloides.

-With all flightless neognaths except Brontornis included: Same results as the first analysis.

-With all flightless neognaths except Brontornis and Patagornis included: Gastornithiforms are stem galliforms, forming a clade with Vegavis. Asteriornis jumps into crown galliforms, on the stem of Cracidae + Phasianidae... or as a phasianid... (This actually isn't as unexpected as it might seem; in some of our preliminary analyses, Asteriornis ended up either in those positions or as a megapode; it has individual skull features that particularly resemble certain extant species.)

-With all taxa included, plus Gastornis and dromornithids constrained to be pan-galloanserans and Patagornis constrained to be sister to Cariama: Gastornithiforms are stem galliforms, Brontornis is a gastornithiform (closer to dromornithids than to Gastornis), strict consensus is super unresolved because Asteriornis jumps around between being a stem anseriform and a phasianid, lithornithids are crown paleognaths, and Anatalavis + Conflicto, Vegavis, and presbyornithids form a clade of stem anseriforms (sometimes with Asteriornis in the mix). (As an aside, the MPTs here are only three steps longer than those from the first analysis.)

-Implied weighting (k = 3) with all taxa included: Patagornis, Gastornis, Brontornis, and dromornithids form a clade of stem galliforms (Brontornis is closest to dromornithids), Vegavis is a stem bird, lithornithids are crown paleognaths, and Asteriornis is a stem galliform or stem megapode.

On Tue, Feb 23, 2021 at 9:18 AM Mickey Mortimer <mickey_mortimer111@msn.com> wrote:
I wouldn't trust the placements of Brontornis, etc. in Agnolin's paper because the analysis was unconstrained, which resulted in paleognaths (with tinamous most basal instead of Struthio) sister to galliforms and anseriforms sister to neoavians. This could easily change the ancestral states of each clade compared to enforcing a molecular scaffold. I'd also like the see a version of the analysis with each large flightless taxon added separately to test whether Brontornis, Gastornis and dromornithids are grouping based on convergence like ratites do in the matrix.

Mickey Mortimer


From: dinosaur-l-request@mymaillists.usc.edu <dinosaur-l-request@mymaillists.usc.edu> on behalf of Tim Williams <tijawi@gmail.com>
Sent: Monday, February 22, 2021 9:00 PM
To: dinosaur-l@usc.edu <dinosaur-l@usc.edu>
Subject: Re: [dinosaur] Brontornis (giant flightless Miocene bird) belongs to Galloanserae (free pdf)
Â
Yes, the Anatidae has produced quite a number of large and flightless forms attributed to insularity: _Garganornis_, _Cnemiornis_, the moa-nalos (_Chelychelynechen_, _Thambetochen_, _Ptaiochen_). Â (I actually wasn't aware of _Cnemiornis_ - thanks!)ÂÂ These large, terrestrial birds are just a subset of the impressive array of flightless anatids (such as the various flightless diving ducks; and the extremely weird and possibly blind 'mole duck' _Talpanas_).ÂÂ

The brontornithids, gastornithids (diatrymids), and dromornithids come up as stem-anseriforms (just as sylviornithids have been interpreted as stem-galliforms). So the two most basal crown Aves clades - Palaeognathae and Galloanserae - were both prone to spawning multiple lines of very large, flightless forms.

On Tue, Feb 23, 2021 at 4:12 AM Brian Lauret <zthemanvirus@hotmail.com> wrote:
Quite, and you can add Miocene Garganornisâ to that list as well as, for some value of giant, Cnemiornisâ and the moa nalo species. Those birds, derived as they are, show the apparent ability of anatids to 'recapitulate' a decidedly more basal-appearing morphology when given the chance. Incidentally, I wonder if that could mean dromornithids, gastornithids and Brontornisâ might not be as basal as their morphologies would indicate. How duck-like would Garganornisâ still have been if it had been given a few million years more to evolve in a clean slate world like the early Paleocene was? What if it had been a stem-anatid, a anseranatid or a screamer, with all the less-derived morphology that would have entailed?


Van: dinosaur-l-request@mymaillists.usc.edu <dinosaur-l-request@mymaillists.usc.edu> namens Tim Williams <tijawi@gmail.com>
Verzonden: maandag 22 februari 2021 10:01
Aan: dinosaur-l@usc.edu <dinosaur-l@usc.edu>
Onderwerp: Re: [dinosaur] Brontornis (giant flightless Miocene bird) belongs to Galloanserae (free pdf)
Â
If correct, the Galloanserae plays host to yet another lineage of giant, secondarily flightless birds in the form of _Brontornis_. This is along with dromornithids, gastornithids, and sylviornithids. Each of these has been proposed to have lost the power of flight independently. In fact, one previous study even suggested that gastornithids may not be monophyletic (Worthy et al., 2017); this would mean _Gastornis_ and _Diatryma_ represent independent events of secondary flightlessness. Overall, this would mean Galloanserae rival the Palaeognathae in the number of independently giant and flightless lineages.Â

On Sun, Feb 21, 2021 at 11:43 AM Ben Creisler <bcreisler@gmail.com> wrote:

Ben Creisler

A new paper with free pdf:

=====

Federico L. Agnolin (2021)
Reappraisal on the Phylogenetic Relationships of the Enigmatic Flightless Bird (Brontornis burmeisteri) Moreno and Mercerat, 1891.
Diversity 13(2): 90
doi: https://doi.org/10.3390/d13020090
https://www.mdpi.com/1424-2818/13/2/90


The fossil record of birds in South America is still very patchy. One of the most remarkable birds found in Miocene deposits from Patagonia is Brontornis burmeisteri Moreno and Mercerat, 1891. This giant flightless bird is known by multiple incomplete specimens that represent a few portions of the skeleton, mainly hindlimb bones. Since the XIX century, Brontornis was considered as belonging to or closely related to phorusrhacoid birds. In contrast to previous work, by the end of 2000 decade it was proposed that Brontornis belongs to Galloanserae. This proposal was recently contested based on a large dataset including both phorusrhacoids and galloanserine birds, that concluded Brontornis was nested among cariamiform birds, and probably belonged to phorusrhacoids. The aim of the present contribution is to re-evaluate the phylogenetic affinities of Brontornis. Based on modified previous datasets, it is concluded that Brontornis does belong to Galloanserae, and that it represents a member of a largely unknown radiation of giant graviportal birds from South America.

Virus-free. www.avg.com