Hummingbird and penguin added to the LRT

Updated September 16, 2017 with a new reconstruction of the skull of Eocypselus.

Today we add
Archilochus (ruby-throated hummingbird), Eocypselus (basal to hummingbirds and swifts), Aptenodytes (emperor penguin) and Gavia (loon or diver (Figs. 1–5) to the large reptile tree (LRT, 1059 taxa). I’m happy to report they nest right where everyone else nests them (Fig. 1), given the very limited number of modern birds in the LRT.

Figure 1. Extant birds and their kin. Hummingbirds and their kin and penguins and their kin have been added using the same list of 230 or so characters that have served to nest reptiles, including mammals.

Figure 1. Extant birds and their kin. Hummingbirds and their kin and penguins and their kin have been added using the same list of 231 characters that have served to nest reptiles, including mammals.

The LRT
is somehow still working as four birds are added, lumped and separated as shown above.

Figure 2. Emperor penguin (Aptenodytes) skeleton. Note the large scapula and short femur.

Figure 2. Emperor penguin (Aptenodytes) skeleton. Note the large scapula and short femur.

Aptenodytes forsteri (Miller 1778; 1.2m tall) the extant emperor penguin is considered a basal penguin, having split from the others about 40 mya. The large scapula anchored strong wing muscles for underwater flying. Note the C-shaped furcula and large patella. Neither are traits listed by the LRT, but fall into place naturally due to the rest of the traits.

FIgure 4. Note the extremely large patella on this Gavia skeleton.

FIgure 4. Note the extremely large patella on this Gavia skeleton.

Gavia stellata (Forster 1788) the extant red-thrated diver Loon toe lobes are connected by webbing. Pedal digit 1 is a vestige. Gavia is similar to Cretaceous era Hesperornis, by convergence. Hackett et al. 2008 nested loons with penguins, and this is confirmed in the LRT. Both share a very short femur among other traits. Note the C-shaped furcula and very large patella (orange).

Figure 3. Ruby-throated hummingbird (Archilochus) skeleton.

Figure 3. Ruby-throated hummingbird (Archilochus) skeleton. Image courtesy of Digimorph.org and used with permission. Colors added.

Archilochus coubris (L. Reichenbach, 1854) is the extant ruby-throated hummingbird. Among the smallest of birds, hummingbirds are only found in the Americas. Their wings hum because they flap so rapidly, approximately 50x/second. They have the highest metabolism during the day, but at night they experience torpor to conserve energy. They survive on nectar from flowers, with which they co-evolved. Hummingbirds are related to swifts and are known form 30-million-year-old fossils. Note the furcula is not C-shaped in lateral view.

Figure 4. Reconstruction of Eocypelus. The pelvis is preserved in ventral view, so is difficult to ascertain in lateral view, but it probably looked very much like that of most other similar birds.

Figure 4. Reconstruction of Eocypelus. The pelvis is preserved in ventral view, so is difficult to ascertain in lateral view, but it probably looked very much like that of most other similar birds.

Eocypselus rowei (Mayr 2003, Ksepka et al. 2013; Eocene, 50 mya) was originally considered a swift and hummingbird ancestor. Eocypselus rowei had a stout humerus, but not so stout as either a swift or hummingbird, both of which were relatively 2/3 the length and 1/3 deeper. Likewise in the swift and hummingbird the radius/ulna is about 2/3 of the length in Eocypselus rowei. The manus of the swift and hummingbird is much longer than the combined length of the ulna and humerus, but not so in the more generalized and primitive Eocypselus rowei. Like Archilochus Eocypselus had a long narrow rostrum. Like Archilochus the sternum was long and deep.

Eocypselus vincenti (Harrison 1984, Mayr 2010, Fig. 5) is a congeneric specimen from the Early Eocene of Europe.

References
Deguine, J-C 1974. Emperor Penguin: Bird of the Antarctic. The Stephen Greene Press, Vermont.
Forster JR 1788. Enchiridion historiae naturali inserviens, quo termini et delineationes ad avium, piscium, insectorum et plantarum adumbrationes intelligendas et concinnandas, secundum methodum systematis Linnaeani continentur. – pp. 1-224. Halae. (Hemmerde & Schwetschke).
Hackett S et al. 2008. A phylogenetic study of birds reveals their evolutionary history. Science 320:1763–1768.
Ksepka DT, Clarke JA, Nesbitt SJ, Kulp FB and Grande L. 2013. Fossil evidence of wing shape in a stem relative of swifts and hummingbirds (Aves, Pan-Apodiformes). Proceedings of the Royal Society B: Biological Sciences 280 (1761): 20130580. doi:10.1098/rspb.2013.0580. Supplementary materials here.
Mayr G 2003. Phylogeny of early Tertiary swifts and hummingbirds (Aves: Apodiformes). The Auk 120(1):145–151, 2003. online
Mayr G 2009. Paleogene Fossil Birds (online) Springer.
Mayr G 2010. Reappraisal of Eocypselus—a stem group apodiform from the early Eocene of Northern Europe. Palaeobiodiversity and Palaeoenvironments 90(4): 395-403.
Reichenbach 1854, L. Aufzählung der Colibris oder Trochilideen in ihrer wahren natiirlichen Verwandtschaft, nebst Schlüssel ihrer Synonymik. Extra., marz, 1–54. besondere Beilage: 1–24.(Enumeration of the colibris or trochilides in their true natural relationship, together with the keys of their synonymy. Extra., Malt, 1-54. Special supplement: 1–24.)

 

wiki/Aptenodytes
wiki/Gavia

 

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