Falcatakely: a basal theropod, not a bird

Updated November 11, 2021
with another look at candidate sister taxa.

O’Connor et al. 2020 present
a late surviving, Late Cretaceous basal theropod dinosaur lacking maxillary teeth, Falcatakely forsterae (Figs. 1–4). The authors reconstructed their crushed and slightly disarticulated fossil using µCT scans.

Figure 1. Falcatakely from O'Connor et al. 2020 µCT scans, then moved slightly on frame 2.

Figure 1. Falcatakely from O’Connor et al. 2020 µCT scans, then moved slightly on frame 2.

Unfortunately
the authors mistakenly considered Falcatakely an enantiornithine bird with a “unique development of beak”. This was due to taxon exclusion. They assumed they had a bird when a more inclusive analysis of omitted taxa indicates they did not.

Figure 1. Falcatakely from O'Connor et al. 2020 µCT scans, then missing elements added in frame 2.

Figure 2. Falcatakely from O’Connor et al. 2020 µCT scans, then missing elements added in frame 2. Note the lacrimal (in red) is partly the jugal (cyan, frame 2).

From the O’Connor et al. abstract:
“Mesozoic birds display considerable diversity in size, flight adaptations and feather organization1,2,3,4, but exhibit relatively conserved patterns of beak shape and development Here we describe a crow-sized stem bird, Falcatakely forsterae gen. et sp. nov., from the Late Cretaceous epoch of Madagascar that possesses a long and deep rostrum, an expression of beak morphology that was previously unknown among Mesozoic birds and is superficially similar to that of a variety of crown-group birds (for example, toucans).”

Note the first two words. They assumed they had a ‘unique’ Mesozoic bird without first testing in a phylogenetic analysis. Evidently they got excited by the possibility of getting published in Nature. That part came true.

Colleagues: The time to get excited is AFTER a wide gamut analysis documents and firmly nests your taxon. Otherwise you’ll end up like the authors of Oculudentavis, which was also mistakenly considered a bird. (I wonder if Nature will demand a similar retraction?)

Figure 3. Falcatakely from O'Connor et al. 2020 µCT scans, then non-palate elements darkened in frame 2. Compare to figure 1 for a more realistic narrowing of the snout.

Figure 3. Falcatakely from O’Connor et al. 2020 µCT scans, then non-palate elements darkened in frame 2. Compare to figure 1 for a more realistic narrowing of the snout.

Whenever you think you have a ‘unique’ anything
add taxa. Expand your taxon list.

Uniqueness in evolution is an oxymoron.
Something should resemble your ‘unique’ taxon.  The O’Connor team’s  mistake was due entirely to taxon exclusion, not looking far enough with a wide enough taxon list.

Figure 4. Cladogram from O'Connor et al. 2020 where they exclude basal theropods and nest Falcatakely with dissimilar enantiornithine birds by default.

Figure 4. Cladogram from O’Connor et al. 2020 where they exclude basal theropods and nest Falcatakely with dissimilar enantiornithine birds by default.

Late-surving Late Cretaceous Falcatakely
nests among the basalmost theropods with Tawa, in the large reptile tree (LRT, 1768+ taxa).

Figure 5. Late Cretaceous Falcatakely compared to scale with Late Triassic Tawa and Early Cretaceous Pengornis. Note the loss and lack of an antorbital fossa in Tawa and Falcatakely. The premaxillary teeth are tiny, distinct from related theropods and distinct from Pengornis. 160 million years separates these new sisters.

Figure 5. Late Cretaceous Falcatakely compared to scale with Late Triassic Tawa and Early Cretaceous Pengornis. Note the loss and lack of an antorbital fossa in Tawa and Falcatakely. The premaxillary teeth are tiny, distinct from related theropods and distinct from Pengornis. 160 million years separates these new sisters.

The lack of maxillary teeth in Falcatakely
is notable in this bird-mimic. Tiny teeth line the down-tipped premaxilla. Note the loss and lack of an antorbital fossa. Now we can look for transitional taxa.

Other bird mimics
are documented here.

With so many theropod fans out there,
let’s see how many confirm the basal theropod affinities of Falcatakely. In either case, it’s still a wonderful fossil find and the authors did a wonderful job of documenting the material. (Next time, just add more taxa).

Happy Thanksgiving
from the USA.


References
O’Connor PM, Turner AH, Groenke JR et al. 2020. Late Cretaceous bird from Madagascar reveals unique development of beaks. Nature (2020). https://doi.org/10.1038/s41586-020-2945-x

wiki/Falcatakely
https://www.ohio.edu/news

Added November 28, a few days after posting:
Others also question the bird hypothesis: Dinosaur Mailing List: A Theropoda blog post questioning the identification of the fossil as a bird… Falcatakely: heterodoxy and pluralism in the Year of Oculudentavis (in Italian) http://theropoda.blogspot.com/2020/11/falcatakely-eterodossia-e-pluralismo.html

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