A flightless, swimming, polar vulture: the great auk

And the puffin
(Fig. 4) is a swimming, polar vulture, too. It’s smaller than the auk (Fig. 1)and it can still fly.

Figure 1. The great auk (genus Pinguinus) is a flightless vulture convergent with penguins.

Figure 1. The great auk (genus Pinguinus) is a flightless vulture convergent with penguins.

The great auk
(genus Pinguinus) is a recently extinct fairly large, penguin-like bird of the North Atlantic. In the large reptile tree (LRT, 1096 taxa) it nests with Coragyps, the extant black vulture.

Figure 2. Pinguinus the great auk skull.

Figure 2. Pinguinus the great auk skull.

Pinguinus impennis (Linneaus 1758; standing 80cm in height) is the recently extinct great auk. Here it nests with the puffin and vultures. Convergent with penguins like AptenodytesPinguinus was flightless, but a good swimmer underwater.

It’s worthwhile to keep
the skeleton of the vulture Coragyps (Fig. 3) in mind when comparing skeletons.

Figure 3. When vultures drift north and start finding fish attractive they evolve into auks and puffins.

Figure 3. When vultures drift north and start finding fish attractive they evolve into auks and puffins.

Coragyps atratus (LaMout 1853; 56 cm in length, 1.5m wingspread) is the extant black vulture and a sister to the giant petrel. Note the similar premaxilla. As in Threskiornis, the head and neck lack feathers.

Everyone knows
Puffins (genus Fratercula) are just small auks that can still fly, even with those short whirring wings. The earlier issue was with the next level of relationships, which are traditionally relegated to suprageneric taxa

Figure 4. The skull of the puffin (genus: Fratercula) with and without the keratin beak.

Figure 4. The skull of the puffin (genus: Fratercula) with and without the keratin beak.

Fratercula arctica (Linneaus 1758; standing 20cm in height) is the extant Atlantic or common puffin. Here it nests with the great auk and vultures, hamerkops (genus: Scopus) and gulls. Both genders have a tall, colorful beak.

According to Wikipedia
birds of prey (Telluraves) includes the taxa shown below (Fig. 5).

Figure 5. Bird relationships according to Wikipedia with comments in red.

Figure 5. Bird relationships according to Wikipedia with comments in red. I never thought the birds would be this messed up. Maybe starting with a smaller taxon list was a good idea this time. Kept things simple.

Unfortunately
The LRT (Fig. 6) does not support several of the traditional bird relationships shown on the Wiki page (Fig. 5), and a good look at the relationships will suggest the gaps between sister clades are just too big. Plus, relying on suprageneric taxa always causes problems and never pinpoints actual sister genera. Test these relationships yourself, as I have, and let me know if you recover anything different.

Figure 5. Subset of the LRT focusing on auk and puffin relatives.

Figure 6. Subset of the LRT focusing on auk and puffin relatives.

I’ve been binging on Burning Man Festival videos
on YouTube and in the spirit of their cashless, gift-giving temporary society, this blog featuring the results of my studies is my gift to you.

References
LeMaout JEM 1853. Les trois regnes de la nature. Regne animal. Histoire naturalle des oiseaux, suivant la classification de M. Isidore Geoffroy-Saint-Hillaire, avec l’indication de leurs moeurs et de leurs rapports avec les arts, le commerce et l’agriculture. Par Emm. Le Maout. L. Curmer. Paris 425 pp.
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/Coragyps atratus
wiki/Atlantic_puffin
wiki/Great_auk

 

Advertisements

Giant flightless birds: Worthy et al. 2017

Worthy et al. nest several giant flightless birds
with chickens and ducks. In the large reptile tree (LRT, 1094 taxa, subset Fig. 1) none of these giants nest with chickens and ducks. Furthermore, chickens (Gallus) and ducks (Anas) don’t nest with each other in the LRT. They don’t look like each other, so their separation makes sense.

Figure 1. Subset of the LRT focusing on birds. Here giant and tiny birds are highlighted. None nest with chickens or ducks, which don't nest with each other.

Figure 1. Subset of the LRT focusing on birds. Here giant and tiny birds are highlighted. None nest with chickens or ducks, which don’t nest with each other.

From the Worthy et al. abstract:
“The extinct dromornithids, gastornithids and phorusrhacids are among the most spectacular birds to have ever lived, with some giants exceeding 500 kg. The affinities and evolution of these and other related extinct birds remain contentious, with previous phylogenetic analyses being affected by widespread convergence and limited taxon sampling. We recognize a robust new clade (Gastornithiformes) for the giant flightless Dromornithidae (Australia) and Gastornithidae (Eurasia, North America). This clade exhibits parallels to ratite palaeognaths in that flight presumably was lost and giant size attained multiple times South America’s largest bird, Brontornis, is not a galloansere, but a member of Neoaves related to Cariamiformes.”

Figure 2. Brontornis parts compared to Gastornis, a close match both in size and morphology.

Figure 2. Brontornis parts compared to Gastornis, a close match both in size and morphology.

Brontornis bits ‘n pieces
Apparently Brontornis is known from a big metatarsus and a big fused dentary (lower beak), perhaps not enough to nest it in the LRT, but South American terror birds (Cariamiformes according to Worthy et al., a clade not supported here, Fig. 1) have a very narrow beak, whereas Brontornis does not. Here (Fig. 2) the shape and size of Brontornis is quite similar to the giant parrot, Gastornis (formerly Diatryma).

While writing this paragraph
I was drawn to the Wiki Brontornis page, which reports (after describing Brontornis as a giant, flightless terror bird), “Recent work (Agnolin 2007, Buffetaut 2014) ]has cast doubt on the hypothesis that Brontornis is a phorusrhacid. Brontornis may actually represent an anseriform” (traditionally ducks, geese and screamers, but the LRT nests screamers apart). Not sure why the Brontornis/wiki author could not make a scientific statement with more confidence. After all, there is only one answer. The other is false.

From the Worthy et al. introductiion
“Landfowl (Galliformes) and waterfowl (Anseriformes) form a diverse and important clade (Galloanseres) that is sister to Neoaves (all other extant non-palaeognath birds).” This is what Prum 2015 recovered using DNA, but it is not what the LRT recovered (Figs. 1–4) using morphology and extinct taxa.

Worthy et al. also report, 
“These giant flightless Galloanseres show striking morphological convergence with flightless palaeognaths (ratites), especially the large extinct Aepyornithidae (elephant birds; Madagascar) and Dinornithiformes (moa; New Zealand).” The LRT recovers elephant birds (Aepyornis) with corn crakes (Crex) and moas (Dinornis) between toucans (Pteroglossus) and parrots (Ara, Figs. 1, 3-5). So Worthy et al. appear to be basing their hypotheses on very shaky ground.

While we’re on the subject of birds
here are a few clade divisions recovered by the LRT.

Figure 2. Bird clades, basal divisions.

Figure 3. Bird clades, basal divisions. Where are all the Late Cretaceous birds? They are waiting to be discovered.

Figure 2. Bird predators and omnivores compared to plant/nectar eaters.

Figure 4. Bird predators and omnivores compared to plant/nectar eaters.

Figure 4. Most basal birds have a premaxilla about the length of the maxilla. That changes in these two basal clades.

Figure 5. Most basal birds have a premaxilla about the length of the maxilla. That changes in these two basal clades. I know I’m pulling a Larry Martin here, but after the phylogenetic analysis, not before. This trait stood out as a readily visible major division at a node that has remained difficult to establish for prior analyses.

The basal radiation of extant birds
has been clouded in mystery in prior studies. Here, with fewer taxa (Figs 1-5), the radiation is quite clear and it probably occurred deep into the Early Cretaceous with a large gap sprinkled with taxa until the Tertiary and then greatly expanded with living taxa.

References
Agnolin F 2007. Brontornis burmeisteri Moreno & Mercerat, un Anseriformes (Aves) gigante del Mioceno Medio de Patagonia, Argentina. Revista del Museo Argentino de Ciencias Naturales, n.s.9, 15-25.
Buffetaut E 2014. Tertiary ground birds from Patagonia (Argentina) in the Tournouër collection of the Muséum National d’Histoire Naturelle, Paris. Bulletin de la Société Géologique de France. 185(3):207–214.
Worthy TH, Degrange FJ, Handley WD and Lee MSY 2017. The evolution of giant flightless birds and novel phylogenetic relationships for extinct fowl (Aves, Galloanseres). Royal Society Open Science 4: 170975. http://dx.doi.org/10.1098/rsos.170975

tetrapodzoology/terror-birds

Padian 2017 examines pterosaur ankles with taxon and paper exclusion

I’ve had a long history with Dr. Kevin Padian,
one of the smartest paleontologists out there. He made important suggestions to my first book, GIANTS and early in his career made a name for himself by reporting on the bird-like traits of the Jurassic pterosaur, Dimorphodon. 

Unfortunately
Dr. Padian has a blind spot. He holds to the invalidated hypothesis that pterosaurs are related to dinosaurs, despite the complete lack of a series of archosaur taxa demonstrating a gradual accumulation of pterosaur traits. He still believes in the clade ‘Ornithodira.’

Ornithodira
Wikipedia reports, “Gauthier…coined and defined a slightly more restrictive node-based clade, Ornithodira, containing the last common ancestor of the dinosaurs and the pterosaurs and all of its descendants. Paul Sereno in 1991 gave a different definition of Ornithodira, one in which Scleromochlus was explicitly added.”

In the large reptile tree (LRT, 1094 taxa) the last common ancestor of dinosaurs and pterosaurs is the Devonian tetrapod, Tulerpeton at the base of the Lepidosaurormorpha – Archosauromorpha split.

Padian 2017
once again links pterosaurs with dinosaurs as he reviews with old illustrations the ankle bone ‘homologies’ of pterosaurs and archosaurs. Unfortunately he ignores Peters (2000a, b) who reidentified certain tarsals based on homologies with Cosesaurus and other fenestrasaurs (see below).

Figure 4. Peteinosaurus and Dimorphodon BMNH4212 pedes. Four tarsals are present on both.

Figure 1. Peteinosaurus and Dimorphodon BMNH4212 pedes. Four tarsals are present on both.

From the Padian abstract:
“The ankle bone assembly of pterosaurs has received little attention, even though it is critical for understanding the functional morphology of the leg and the foot and has far-reaching implications for interpretations of stance and gait in ornithodirans in general, as well as for any role the leg may have had in the flight of pterosaurs. Of particular importance are the distal tarsal bones, which are seldom preserved clearly.”

Padian found only two large (medial and lateral) tarsals in Dimorphodon, but most early pterosaurs have four tarsals (Fig. 1), as some of his figures show.  In Dimorphodon and Pteranodon the distal and proximal tarsals appear to fuse to one another creating two large side-by-side tarsals with a concave surface for articulation with the tibia/fibula. In all other pterosaurs the proximal tarsals are the astragalus and calcaneum. The ‘distal tarsals’ are actually distal tarsal 4 + the centrale sometimes accompanied by a tiny distal tarsal 3 (Peters 2000a) based on homologies with several tritosaur lepidosaurs, like Macrocnemus.

“Their concave proximal facets articulate with the medial and lateral condyles (comprising the astragalus and, at least basally, the calcaneum) of the tibiotarsus.”

The proximal tarsals are not part of the tibia in pterosaurs. Pterosaurs do not fuse the tibia and tarsus to form a tibiotarsus (Peters 2000a).

“Distally, they articulate with metatarsals II–IV, and the relatively large metatarsal V articulates on the distolateral side of the lateral distal tarsal.”

Not quite. That’s distal tarsal and the calcaneum articulate with metatarsal 5. That is exactly what happens, as Padian shows, in the archosauriforms Euparkeria, Crocodylus and Lagerpeton. That is exactly what also happens in the tritosaurs HuehuecuetzpalliMacrocnemus, Langobardisaurus, Cosesaurus and Sharovipteryx (Peters 2000a and ReptileEvolution.com).

“The homology of these bones in pterosaurs can be established with reference to other early-branching ornithodirans, and the morphology of the bones implies similar functional roles and ranges of motion.”

Convergence here with tritosaur lepidosaurs. Worth looking at.

“The medial distal tarsal is likely the fusion of distal tarsals 2 C 3, and the lateral distal tarsal is distal tarsal 4, a pattern reflected in ontogeny.”

No and yes. In tritosaurs distal tarsals 1–3 are tiny vestiges. Distal tarsal 3 is retained in many long-tailed pterosaurs. Distal tarsal 4 remains large. The proximal and distal elements fuse in Pteranodon. The medial centrale is Padian’s medial distal tarsal (Peters 2000a).

“The pterosaur ankle was capable of plantarflexion, but adduction and abduction of the feet were greatly limited.”

True.

“A synoptic survey of available tarsal bones of pterosaurs shows that the morphology of these bones remained relatively unchanged from the most basal pterosaurs to the pteranodontids and the azhdarchoids.”

True.

“Comparisons among a variety of ornithodirans show that the basic functional pattern did not vary importantly, although some ornithodiran subgroups evolved unique schemes of development and sequential ossification.”

True.

Dr. Padian writes:
“Pterosaurs were not thought to be particularly close to dinosaurs, or to any other archosaurs.”

When? That’s not current and traditional.

“Bennett, as noted above, does not accept that pterosaurs are ornithodirans. So it is all the more striking that these authors come to the same conclusion as functional morphologists who accept that pterosaurs are ornithodirans. The consensus of these authors is that pterosaurs, like dinosaurs and other ornithodirans, had a mesotarsal ankle that functioned as a hinge joint. Because the knee was also a hinge joint, as were the metatarso-phalangeal joint and the interphalangeal joints (Padian, 1983b, 1991), and the hip joint effectively allowed only protraction and retraction (see Schaeffer, 1956, and also Padian, 1983b), the gait would have been parasagittal and the stance erect (Padian, 2008). No argument has ever been made to counter these observations.”

No argument can be made to counter these observations. However, they can be expanded. Padian ignores the fact that other clades, like lepidosaurs, are also capable of bipedal locomotion and that some (like those list above) also have a simple hinge ankle joint. He also fails to note that in some pterosaurs the femoral head is at right angles to the shaft, but in others it is almost in line with the shaft, creating a splayed femur, like a lepidosaur, yet, like certain lepidosaurs, still capable of erect bipedal locomotion (Fig. 2).

Padian discusses the splayed femur concept
and agrees with Unwin that it would have provided a clumsy, sprawling gait. This is incorrect as anyone can learn from making museum-quality skeletons that have splayed femora and erect hind limbs. The angles all work out (Fig. 2).

And running bipedal lizards are not clumsy. They are speedy wonders!

Standing Pteranodon

Figure 2. Standing Pteranodon with sprawling femora. We’ve known this for 17 years.

Way back in the 1980s,
Kevin Padian and Chris Bennett. in the same conversation. cautioned me to employ phylogenetic analysis in my studies. Given present data in the academic literature (Peters 2000a, b) you have to ask yourself why Padian, like Bennett (2012) restricted his taxon list to just archosauromorphs.

For those who wonder why I don’t publish,
maybe Padian’s paper will offer some insight. I have published several papers on pterosaur relationships, wings and feet. None were cited by Dr. Padian. He is listed in the acknowledgments of Peters 2000a for reading an earlier version of the manuscript. The last time we e-mailed he was angry that I made several of the above observations.

References
Bennett SC 2012. The phylogenetic position of the Pterosauria within the Archosauromorpha re-examined. Historical Biology. iFirst article, 2012, 1–19.
Padian K 1983. 
Osteology and functional morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea) based on new material in the Yale Peabody Museum, Postilla, 189: 1-44.
Padian K 2017.
Structure and evolution of the ankle bones in pterosaurs and other ornithodirans. Journal of Vertebrate Paleontology.
DOI: 10.1080/02724634.2017.1364651
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.

Spoonbill: it really is a duck-stork

Maybe the spoonbill
(Fig. 1) is the closest thing we have today to Presbyornis (Fig. 2).

Figure 1. The roseate spoonbill (genus: Platalea) in vivo. Traditionally spoonbills and storks have been nested together. Here it nests between storks and ducks.

Figure 1. The roseate spoonbill (genus: Platalea) in vivo. Traditionally spoonbills and storks have been nested together. Here it nests between storks and ducks.

Short one today. Pretty obvious results.
The extant spoonbill (Platalea) with its featherless face (Fig. 1), gives the impression of being very ancient. The large reptile tree (LRT, 1090 taxa) nests it between storks (check out those long legs) and ducks (check out that spoon bill), including long-legged ducks (Fig. 2) like Presbyornis.

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.

The only trouble is
spoonbills typically nest only with storks, far from ducks, which typically nest closer to screamers, like Chauna.

You can see the gradual accumulation of traits
using morphological traits. That doesn’t always happen with DNA.

From the ReptileEvolution page:
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.

References
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/Platalea
wiki/Anas
wiki/Presbyornis

Like dippers, wrens are not passerines either

FIgure 1. Eurasian wren, Troglodytes troglodytes, skull in three views

FIgure 1. Eurasian wren, Troglodytes troglodytes, skull in three views

On a reader request that I became curious about
the Eurasian wren (Troglodytes troglodytes) has been added to the large reptile tree (LRT, 1090 taxa) because it typically nests with the tiny dipper (Cinclus), which nests between kingfishers and murres + penguins.

Figure 1. The Eurasian wren, Troglodytes troglodytes, nests with the dipper, Cinclus, close to kingfishers and penguins.

Figure 1. The Eurasian wren, Troglodytes troglodytes, nests with the dipper, Cinclus, close to kingfishers and penguins.

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

Figure 1. Subset of the LRT focusing on extant birds, especially penguins. Troglodytes nests with Cinclus.

To no one’s surprise,
the wren nests with the dipper. And both nest between kingfishers and murres + penguins, not near Passer, the sparrow. Let’s not forget that other small birds with short wings, like hummingbirds, nest nearby. 

Troglodytes troglodytes (Vieillot 1809; 12cm long,is the Eurasian wren.  Here the cranium is further expanded.

References
Vieillot LJP 1809. Histoire naturelle des oiseaux de l’Amérique Septentrionale

wiki/Troglodytes_wren

What is a flamingo in the cladogram of birds?

In the present subset
of the large reptile tree (LRT, 1090 taxa, Fig. 3) flamingoes (genus: Phoenicopterus, Fig. 1) nest with the seriema (genus: Cariama, Fig. 2). That makes the flamingo a sort of bird of prey, now concentrating on tiny plankton (algae + invertebrates). That’s why they are so distinct.

Wikipedia lists several studies
that nest flamingoes with ducks, spoonbills and/or doves.

Prum et al. 2015 used DNA
to nest flamingoes with grebes. These submersible sharp-rostrum, hind limb swimmers have not yet been added to the LRT, but grebes look more like loons, similar to Gavia. Until that analysis,  here’s a loon skeleton online. So when grebes are added, I’ll let you know how that works out.

The closest tested relative
of Phoenicopterus in the Prum et al. tree is Uria, the murre, which we looked at yesterday, Here, Uria nests between dippers and penguins, far from Phoenicopterus (Fig. 3).

So, apparently there is no consensus
out there regarding flamingo relatives. Are the flamingo-like traits of Cariama convergent or homologous? The answer has to come from comparative anatomy. DNA fails too often to deliver sisters who actually look like one could evolved from the other or from a common ancestor sharing a long list of traits.

Figure 1. Phoenicopterus, the flamingo, currently and provisionally nests with Cariama in the LRT.

Figure 1. Phoenicopterus, the flamingo, currently and provisionally nests with Cariama in the LRT.

Phoenicopterus chilensis (Molina 1782) is the extant flamingo, a long-legged filter-feeder with pink plumage. Here it ness with Cariama, the seriema.

Figure 2. The seriema(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 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.

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. At present it is easy to see why they nest together. And this is where the LRT shines.

Figure 7. The addition of the cuckoo, Coccyzus, to the LRT cements the nesting of the roadrunner, Geococcyx, with the heron, Ardea.

Figure 3. Taking advantage of an earlier cladogram, note the nesting of Phoenicopterys with the birds of prey, including Cariama.

If anyone can find a better match
for flamingoes, please let me know. Otherwise, you heard it here first. Meanwhile, I’m surprised to see what I learn in just a few hours has not been discovered before. This is not rocket science.

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.
Molina JI 1782. Saggio sulla Storia Naturale del Chili. Bologna, Stamperia di S. Tommaso d’Aquino. 349 pp.

wiki/Flamingo
wiki/Seriema

 

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