Bird cladogram 2018 and the origin of penguins

Bird interrelationships
are coming together (Fig. 1). Here, wrens, dippers and woodpeckers now nest with crows, jays and grackles. Little else has changed. A few more taxa were also added.

Figure 1. Subset of the LRT focusing on birds. Here various aspects of birds are shown, including age, teeth, feeding behavior and basic clades.

Figure 1. Subset of the LRT focusing on birds. Here various aspects of birds are shown, including age, teeth, feeding behavior and basic clades. Four images change every 5 seconds.

The interesting thing I find in this cladogram
(Fig. 1) from the large reptile tree (LRT, 1146 taxa) is the highly derived placement of the penguin Aptenodytes. That’s really to be expected. However, a basal penguin, Waimanu (Slack et al. 2006; Fig. 2) nests from the Middle Paleocene (61.6 mya), soon after the K-T extinction event. That’s not really expected if one follows traditional cladograms that have birds radiating quickly and widely from the K-T boundary on out. Or maybe they did!

Figure 2. Waimanu is the penguin ancestor from the Middle Paleocene.

Figure 2. Waimanu is the penguin ancestor from the Middle Paleocene.

Wikipedia reports,
“Both DNA sequence analyses and anatomy argue for a close relationship between penguins and loons, with penguins being specialized for wing-propelled diving, and loons for foot-propelled diving.” Slack et al. 2006 nest penguins with storks, loons an petrels in order of increasing distance. I don’t see kingfishers in that list. And I wonder which stork was tested, because the Jabiru (see below) is traditionally considered a stork.

Figure 1. The extant murre, Uria, and the extant penguin, Aptenodytes to scale.

Figure 3. The extant murre, Uria, and the extant penguin, Aptenodytes to scale.

The LRT
(subset Fig. 1) nests penguins and murres with kingfishers (volant diving birds, Fig. 4) and the giant stork-like kingfisher, Jabiru, (which, of course, does not dive). These are close to loons + grebes (poorly flying diving birds) and terns (oceanic soaring diving birds, Fig. 5).

Figure 1. Megaceryle, the belted kingfisher may be a neotonous jabiru (genus: Jabiru).

Figure 4. Megaceryle, the belted kingfisher may be a neotonous jabiru (genus: Jabiru).

With Neornithes originating in the Early Cretaceous,
evolution had plenty of time to create penguins throughout the Cretaceous. But we don’t find their fossils then. Did Neornithes remain in small, out of the way enclaves, barely evolving, waiting, like mammals, to emerge after the Cretaceous?

Figure 3. Skeleton of Thalasseus, the crested tern.

Figure 5. Skeleton of Thalasseus, the crested tern. Scale bar = 10 cm.

Or did neornithine birds evolve throughout the Cretaceous
in areas that don’t often preserve fossils? Good question. 

Here’s a video worth seeing on Kingfishers.
Think of them as pre-penguins.

References
Slack KE. et al. 2006. Early Penguin Fossils, plus Mitochondrial Genomes, Calibrate Avian Evolution. Molecular Biology and Evolution, 23(6): 1144-1155.

online here.

http://www.otago.ac.nz/geology/research/paleontology/waimanu.html

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Stinkbird on steroids = Gastornis!

Figure 1. Gastornis (Diatryma) was a large bird of the late Paleocene,/early Eocene. It appears to share many traits withy the living hoatzin, Opisthocomus.

Figure 1. Gastornis (Diatryma) was a large bird of the late Paleocene,/early Eocene. It appears to share many traits withy the living hoatzin, Opisthocomus. Pedal digit 1 was likely retroverted.

Adding
giant Gastornis (Diatryma) (Fig. 1) to the large reptile tree brings to mind an old Warner Bros. Tweetybird/Sylvester cartoon, nicknamed on YouTube, “Tweety on Steroids” (Fig. 1).

I could not help noticing
a long list of synapomorphies shared between the giant flightless Paleocene bird, Gastornis, with the living stink bird, more commonly known as the hoatzin, Opisthocomus hoazin. The nickname ‘stink bird’ comes from its smell, derived from the rotting vegetation of its herbivorous diet. In Gastornis, a lack of sharp talons, a lack of a hooked beak together with its heavy bones and large gut indicate an herbivorous diet as well.

Figure 1. Warner Bros. cartoon on YouTube (click to view) transforms little Tweety into a giant monster, like Gastornis.

Figure 1. Warner Bros. cartoon on YouTube (click to view) transforms little Tweety into a giant monster, like Gastornis.

A comparison to Opisthocomus 
(Fig. 2) is interesting, and will follow, but perhaps more interesting, Gastornis shares several traits with non-avian dinosaurs, evident atavisms, not visible on known sister taxa.

Figure 2. The hoatzin, Opisthocomus, skeleton is quite similar to that of Gallus, the chicken. Juveniles do not have fused fingers.

Figure 2. The hoatzin, Opisthocomus, skeleton is quite similar to that of Gallus, the chicken. Juveniles do not have fused fingers.

Like non-avian dinosaurs, Gastornis has

  1. complete upper temporal arch (postorbital + squamosal)
  2. orbit not confluent with temporal fenestrae
  3. orbit taller than wide
  4. postfrontal
  5. ribs without uncinate processes
  6. lack of fused dorsal vertebrae
  7. coracoid approaching disc-like
  8. orbit shorter than postorbital skull length
  9. maxilla taller than 40% orbit height
  10. jugal with elongate qj process, short suborbital portion
  11. parietal skull table not broad, weakly constricted
  12. occiput close to quadrates
  13. ilium posterior process longer than anterior process (also as in Struthio and Hesperornis)
Figure 3. Gastornis (Diatryma) skull model with bones identified.

Figure 3. Gastornis (Diatryma) skull model with bones identified.

Like Opisthocomus, Gastornis has

  1. nasals connect medially
  2. descending jugal
  3. large gut/herbivorous diet
  4. dentary contributes to coronoid
  5. mandibular fenestra
  6. mandible ventral shape: 2 tier convex

References
Cope ED 1876. On a gigantic bird from the Eocene of New Mexico. Proceedings of the Academy of Natural Sciences of Philadelphia 28 (2): 10–11.
Matthew WD, Granger W and Stein W 1917. The skeleton of Diatryma, a gigantic bird from the Lower Eocene of Wyoming. Buletin of the American Museum of Natural History, 37(11): 307-354.
Hébert E 1855a. Note sur le tibia du Gastornis pariensis [sic] [Note on the tibia of G. parisiensis]. C. R. Hebd. Acad. Sci. Paris (in French) 40: 579–582.
Hébert E 1855b. Note sur le fémur du Gastornis parisiensis [Note on the femur of G. parisiensis]. C. R. Hebd. Acad. Sci. Paris (in French) 40: 1214–1217.
Prévost C 1855. Annonce de la découverte d’un oiseau fossile de taille gigantesque, trouvé à la partie inférieure de l’argile plastique des terrains parisiens [Announcement of the discovery of a fossil bird of gigantic size, found in the lower Argile Plastique formation of the Paris region]. C. R. Hebd. Acad. Sci. Paris (in French) 40: 554–557.
Statius Müller PL 1776. Des Ritters Carl von Linné Königlich Schwedischen Leibarztes &c. &c. vollständigen Natursystems Supplements- und Register-Band über alle sechs Theile oder Classen des Thierreichs. Mit einer ausführlichen Erklärung. Nebst drey Kupfertafeln.Nürnberg. (Raspe).

wiki/Hoatzin
wiki/Gastornis