Dippers, murres and the origin of penguins

Today
we’re going to take a heretical look at the origin of penguins, those short-legged, super-insulated, flightless, fish- & squid-eaters. Some can dive for 22 minutes down to 550 meters.

According to Wikipedia
the relationships of the penguin subfamilies (order: Sphenisciformes) and the placement of penguins among the birds “is not resolved.” By contrast, in the LRT the relationship of penguins among birds is completely resolved.

Basal penguins,
like Waimanu, are known from Antarctica and New Zealand from the early Paleocene. Waimanu was flightless and likely swam with both its short wings and paddling feet. This derived bird at the K-T boundary points to a much earlier radiation of more primitive, crane-like extant birds, apparently starting just before Yanornis in the Early Cretaceous.

Figure 1. Subset of the LRT focusing on extant birds, especially penguins.

Figure 1. Subset of the LRT focusing on extant birds, especially penguins.

In the large reptile tree
(LRT, 1089 taxa) penguin ancestors going back to Devonian fish are recovered. However, presently and provisionally two taxa are proximal penguin sisters in the LRT and these are derived from even more basal and high-energy terns, swifts and kingfishers.

Figure 1. Cinclus, the dipper is basal to penguins.

Figure 1. Cinclus, the dipper is basal to penguins.

Dippers like Cinclus (Fig. 2) traditional nest with Passer, the seed-eating sparrow. Not here (Fig. 1). Cinclus flies, walks and dips into fast moving freshwater streams to walk underwater. It flies underwater on short wings and it likes cold waters. Nasal flaps prevent water from entering the nostrils. The bones are solid to decrease buoyancy and the feathers are waterproof. The eyes can focus underwater.

Dippers can remain underwater for up to 30 seconds. They have a slower metabolism, despite their active lifestyle. Dippers do not live in colonies and they are smaller than their phylogenetic predecessors.

Phylogenetic miniaturization,
(the Lilliput effect) as we have seen with reptiles, mammals, pterosaurs, snakes, bats, dinosaurs, turtles, etc., leads to key internal structural changes. In the case of Cinclus, these apparently involve those initial adaptations to cold and water. And with these traits in its toolbox, the descendants of Cinclus were free to grow larger, get fatter, loser their ability to fly, gain the ability to handle deeper water and withstand colder nesting grounds away from predators.

FIgure 2. Cinclus, Uria and Aptenodytes, three taxa in the origin of penguins.

FIgure 2. Cinclus, Uria and Aptenodytes, three taxa in the origin of penguins. Despite their apparent differences, the LRT nests these three taxa together in a single clade.

Representing another transitional phase
Murres like Uria (Fig. 2; 45cm), traditional nest with snipes, plovers, terns, stilts, gulls puffins and auks (= Charadriiformes),. That’s a pretty diverse clade. Some of these also appear in the penguin clade of the LRT. Many workers consider murres to be unrelated to penguins, despite appearances. Murres are all north of the equator, while penguins stay south. Uria has pelican-like plumage (black and white) and is better adapted to swimming underwater (up to  4 minutes) with a longer torso and longer sternum. Digit 1 becomes a vestige and the rib cage extends nearly to the ankle. Murres live in colonies near sea waters.

Penguins like Aptenodytes (Fig. 3) traditionally nest with loons, like Gavia. Here (Fig. 1) they don’t. Penguins are flightless, trend toward larger, can swim better and seek larger prey. Finger 1 disappears. The pygostyle straightens out. The scapula grows larger. The metatarsus becomes shorter than the pedal digits. Again, these are all minor and gradual accumulations of traits.

 

Cinclus cinclus (Linneaus 1758 (Sturnus cinclus); Borkhausen 1797; 18 cm long) is the extant white-throated dipper. Its short wings whirr swiftly and without pauses or glides. From a perch it will walk into the water and deliberately submerg. It ‘flies’ underwater. Prey includes aquatic invertebrates. This is one of the most basal taxa among neognath birds. This clade developed a very deep sternum.

Uria lomvia (Linneaus 1758; 45cm tall) is the extant thick-billed murre. It is a strong flyer, both in the air and underwater. Basal to penguins, and derived from Cinclus, Uria also has an elongate sternum, two more dorsal vertebrae + ribs, and short wings.

Here is a unique video of YouTube. of a beluga whale toying with a tiny dipper… or is it the other way around. Enjoy! Nullius in verba

Figure YouTube: Click to see the entire charming video of a beluga whale making friends with a tiny dipper.

Figure YouTube: Click to see the entire charming video of a beluga whale making friends with a tiny dipper.

References
Deguine, J-C 1974. Emperor Penguin: Bird of the Antarctic. The Stephen Greene Press, Vermont.
Hackett S et al. 2008. A phylogenetic study of birds reveals their evolutionary history. Science 320:1763–1768.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

wiki/White-throated_dipper
wiki/Penguin
wiki/Uria

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Roadrunner skull and surface features

These two images of the extant roadrunner
(Fig. 1; genus: Geococcyx) were so close to each other, they presented a great opportunity to match skull to surface features on one of our favorite birds.

Figure 1. GIF animation of Geococcyx skull matched to surface feathers. Distinct from other birds tested so far, the nares is far forward, apart from the antorbital fenestra.

Figure 1. GIF animation of Geococcyx skull matched to surface feathers. Distinct from other birds tested so far, the nares is far forward, apart from the antorbital fenestra.

A minimum of guesswork
and/or imagination was used in the creation of this image. Since the skull is a cast, sutures were ‘sutured’ to create a single object.

Geococcyx californum 
(Wagler 1831; up to 60 cm longl) the extant roadrunner is a small terrestrial heron and a basal neognath with a posteriorly rotated pedal digit 4, unrelated to parrots and toucans with a similar toe. Traditionally roadrunners are considrered part of the cuckoo family. When cuckoos get tested, they may also nest here. They have shorter hind legs.

Figure 2. Geococcyx the roadrunner skeleton. Note the crane-like proportions of this small land heron.

Figure 2. Geococcyx the roadrunner skeleton. Note the crane-like proportions of this small land heron, probably a late-surviving Early Cretaceous member of the Euornithes.

And where does the roadrunner nest
in the large reptile tree (LRT 1087 taxa)? Between toothy Yanornis and toothless Ardea, the heron, all three at the base of the neognath birds, not surprisingly close to Sagittarius and Cariama, two other extant bird terrestrial predators with long hind limbs.

Nullius in verba

References
Wagner JG 1831. Einige Mitheilungen über Thiere Mexicos. Oken’s Isis 24:510–535.

wiki/Roadrunner

Intriguing little raptorial foot on a living bird

Figure 1. Foot of the extant seriema (genus Cariama) with digit 2 elevating the sharp and highly curved killing claw.

Figure 1. Foot of the extant seriema (genus Cariama) with digit 2 elevating the sharp and highly curved killing claw.

The extant seriema
(Cariama cristatus) has an elevated pedal digit 2 killer claw, just like that of its Mesozoic distant relatives, Velociraptor and Deinonychus. This is yet one more example of ancient genes expressing themselves once again after traits have been lost in birds.

Figure 2. The serieam (genus: Cariama) is the closest taxa to Yanornis in the LRT. The two resemble one another in most details, but Cariama lacks teeth, has a retracted naris and an elevated pedal digit 1.

Figure 2. The seriema (genus: Cariama) is a long-legged high-grass predator with a raptor-like foot. 

At the Paleognath/Neognath transition is Yanornis.

A quick note today best told in images
Back at the studio I’m still busy trying to unravel basal neognath birds (extant birds sans the kiwi, ostrich, tinamou and their allies). Details are popping out, like this one today.

Figure 1. Yanornis (the holotype specimen, not the enantiornithine) was a likely small prey predator based on its descendants (see figures 2-4).

Figure 1. Yanornis (the holotype specimen, not the enantiornithine) was a likely small prey predator based on its descendants (see figures 2-4). This taxon is transitional between tinamous (paleognath) and seriemas (neognath). Even though the best data is the crude drawing, it serves well to distinguish this key taxon.

Along with other
toothed birds, like Ichthyornis, Yanornis (Fig. 1, the holotype IVPP V 12558, not the other specimens) nests between paleognaths and neognaths.  Specifically it nests between primitive tinamous and derived seriemas (Fig. 2) in the large reptile tree (LRT, 1085 taxa, still not yet updated).

Yanornis martini holotype (IVPP V12558, Zhou and Zhang 2001; Early Cretaceous) as originally traced and reconstructed by moving those traced lines back to in vivo positions. This is a euornithine bird with several traits retained by living birds not shared with the STM9-52 specimen. The pygostyle appears here by convergence with other Cretaceous birds.

Phylogenetically,
Yanornis is the proximal outgroup taxon to the post-Cretaceous toothless birds and it a sister also gave rise to all extant neognath birds. The bony teeth are derived as known outgroup tinamou taxa do not have teeth.

Figure 2. The serieam (genus: Cariama) is the closest taxa to Yanornis in the LRT. The two resemble one another in most details, but Cariama lacks teeth, has a retracted naris and an elevated pedal digit 1.

Figure 2. The serieam (genus: Cariama) is the closest taxa to Yanornis in the LRT and one of the most primitive of all neognaths. The two resemble one another in most details, but Cariama lacks teeth, has a retracted naris and an elevated pedal digit 1.

 

The seriema (genus: Cariama)
is the closest taxa to Yanornis in the LRT and one of the most primitive of all neognaths. The two resemble one another in most details, but Cariama lacks teeth, has a retracted naris, a short pedal 2.1 and an elevated pedal digit 1 among other differences.

Cariama cristatus (Linneaus 1766) is the extant seriema, a grasslands predator from South America. It flies only to escapte predators. Here it is basal to the flamingo, Phoenicopterus.

By the way,
Late Cretaceous Vegavis is now the last common ancestor of all extant birds, contra my earlier results with fewer taxa and more mistakes. Moreover, with Yanornis in the Early Cretaceous, it would not be surprising to find more ´Euornithes in the Cretaceous.

References
Linneaus C 1766. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. Holmiae. (Laurentii Salvii).: 1-532.
Zhou Z. and Zhang F. 2001. Two new ornithurine birds from the Early Cretaceous of western Liaoning, China. Chinese Science Bulletin, 46 (15), 1258-1264.

A fresh reconstruction of Pelagornis nests it with Macronectes

Updated October 12, 2017 with a longer maxilla and a shorter mandible and a new nesting. 

Pelagornis chilensis (Lartet 1857, Mayr and Rubilar-Rogers 2010; Miocene; MNHN SGO.PV 1061; Fig. 1) is an extinct giant soaring bird here related to Macronectes, the giant Southern petrel (Fig. 2). Bony, not true teeth, developed along the jaw margins. The external naris was divided by bone.

Mayr and Rubilar-Rogers reported,
“We finally note that the phylogenetic affinities of bony-toothed birds still have not been convincingly resolved.” I made a fresh reconstruction (Fig. 1) and tested it against a long list of Cretaceous and post-Cretaceous birds to see where it nests.

FIgure 1. Pelagornis, new reconstruction of skull along with overall reconstruction from Mayr and Rubilar-Rogers

FIgure 1. Pelagornis, new reconstruction of skull along with overall reconstruction from Mayr and Rubilar-Rogers

Pelagornis is an earlier larger version of
the large soaring sea birds, the petrels (Figs. 2, 3), not far from New World vultures.

Figure 5. Macronectes, the Southern giant petrel, in vivo.

Figure 2. Macronectes, the Southern giant petrel, in vivo.

Figure 3. Macronectes giganteus, the extant Southern giant petrel.

Figure 3. Macronectes giganteus, the extant Southern giant petrel. Note the long maxilla. 

My earlier error was realized
when birds with long maxillae, like Macronectes, starting appearing in the LRT.

References
Lartet E 1857. Note sur un hum´erus fossile d’oiseau, attribu ´e `a un tr `es-grand palmip`ede de la section des Longipennes. Comptes rendus hebdomadaires des S´eances de l’Acad´emie des Sciences (Paris) 44:736–741.
Mayr G and Rubilar-Rogers D 2010. Osteology of a new giant bony-toothed bird from the Miocene of Chile, with a revision of the taxonomy of Neogene Pelagornithidae. Journal of Vertebrate Paleontology 30(5):1313-1340.

wiki/Pelagornis

Roof and floor, no walls: the skull of Aepyornis

Figure 1. The skull of Aepyornis is lacking lateral bones that help delineate fenestra, all of which are confluent.

Figure 1. The skull of Aepyornis is lacking lateral bones that help delineate fenestra, all of which are confluent.

Figure 2. Aepyornis maximus was the heaviest of all birds. Once considered a ratite, Aepyornis nests in the LRT with ducks, like Ana (Fig. 3).

Figure 2. Aepyornis maximus was the heaviest of all birds. Once considered a ratite, Aepyornis nests in the LRT with ducks, like Ana (Fig. 3).

Sure it looks like a giant ostrich,
but Aepyornis nests closer to geese and ducks. And let’s not forget that the basal duck, Presbyornis (Fig. 4), also had long, stork-like legs.

Aepyornis maximus (Geoffroy Saint-Hilaire) is the recently extinct elephant bird restricted to Madagascar. It is the heaviest of all birds and 3m tall. Long considered a ratite related to Struthio and especially Apteryx, here this taxon is recovered as a giant flightless goose. Note: all the fenestrae are confluent.

Figure 3. Anas, the mallard duck, shares more trait with Aepyornis than with other taxa in the LRT.

Figure 3. Anas, the mallard duck, shares more trait with Aepyornis than with other taxa in the LRT.

Anas platyrhynchos (Linneaus 1758) is the extant mallard duck. It has shorter legs than Presbyornis. This toothless bird has toothlike serrations on the keratin that covers its broad bill.

Figure 4. Presbyornis is the prehistoric long-legged duck, close to the elephant bird, Aepyornis.

Figure 4. Presbyornis is the prehistoric long-legged duck, close to the elephant bird, Aepyornis.

Presbyornis pervetus (Wetmore 1926; Olson and Feduccia 1980; earliest Eocene, 62 mya) is one of the first of the clade Anseriformes (ducks, geese and kin). It is known from scattered bones and was originally considered a flamingo relative, due to its long legs. The duck-like skull was found later. This clade is the sister to the predatorial long-legged taxa, like Cariama and Sagittarius.

References
Geoffroy Saint-Hilaire I 1851. [Note sur les onze espèces nouvelles do Trochilidés de M. Bourcier.] Compt. Rend. de l’Acad. Sci 32:188.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
Olson SL and Feduccia A 1980. Presbyornis and the origin of the Anseriformes (Aves: Charadriomorphae). Smithsonian Contributions to Zoology 323: 1–24.
Wetmore A 1926. Fossil birds from the Green River deposits of Eastern Utah. Annals of the Carnegie Museum 16: 391-402.

wiki/Anas
wiki/Presbyornis
wiki/Aepyornis

Adding more birds to the LRT

Over the last week or so
more birds have been added to the large reptile tree (LRT, 1074 taxa, subset Fig. 1). Many are still with us. Others are recently extinct. Still others are known only from the Paleocene.

Figure 1. Subset of the LRT focusing on extant birds and their closest kin.

Figure 1. Subset of the LRT focusing on extant birds and their closest kin.

I was surprised to see

  1. the toothed birds, Yanornis, Ichthyornis and Hesperornis nest within the clade of extant birds. That means, like Pelagornis, some sort of teeth came back.
  2. the moa, DInornis and Gastornis (= Diatryma) both nest close to parrots (like Ara) and the hoatzin (Opisthocomus). Here ratites are no longer monophyletic. Wikipedia notes, “The systematics involved have been in flux.”
  3. ducks, like Anas, are close to predatory birds, like Sagittarius
  4. the Solnhofen bird, Jurapteryx (= Archaeopteryx) recurva nests at the base of the clade of extant birds
  5. Details later.