Swifts and Swallows

They look alike on the outside…
but everyone knows they are different inside. That’s been known for a long time. Swifts and swallows also nest far apart from one another in the large reptile tree (LRT, 1099 taxa).

Figure 1. Subset of the LRT focusing on extant birds and their kin. Here swifts (Apus) nest apart from swallows (Hirundo).

Figure 1. Subset of the LRT focusing on extant birds and their kin. Here swifts (Apus) nest apart from swallows (Hirundo).

Rampant convergence in the bird subset of the reptile cladogram.
We’ve seen this before, recently, in penguins + murres versus auks + puffins.

Figure 2. Skull of Hirundo, the barn swallow.

Figure 2. Skull of Hirundo, the barn swallow, closer to wrens and dippers.

When you get inside their heads
Hirundo, the barn swallow (Fig. 2) and Apus, the common swift, are readily different.

Figure 3. Skull of Apus, the common swift, closer to hawks and owls.

Figure 3. Skull of Apus, the common swift, closer to hawks and owls.

Apus apus (Linneaus 1758) is the common swift. Long thought to be related to hummingbirds like Archilochus, Apus nests here with falcons and owls.

Hirundo rustica (Linneaus 1758) is the extant barn swallow. Swallows are not related to, but convergent with swifts like Apus. Here they nest with wrens and dippers, but with a shorter rostrum/larger orbit and longer wing feathers.

These direct comparisons
are teaching me something I never thought of learning, but now find fascinating.

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.

Advertisements

Woodpeckers nest with swifts and wrens + dippers

… and not far from murres and penguins.
This clade has evolved into a wide gamut of niches with similar skulls that share many traits.

Figure 1. Skull of Melanerpes, a woodpecker. Note the robust mandible and rostrum. The tongue bones extend over the back of the skull anchored over the nares.

Figure 1. Skull of Melanerpes, a woodpecker. Note the robust mandible and rostrum. The tongue bones extend over the back of the skull anchored over the nares.

Melanerpes aurifrons (Wagler 1829) is the extant golden-fronted woodpecker. Tongue bones extend over the back of the skull to anchor over the nares. The skull is more robust than in related forms, a trait that makes wood pecking possible. Skull and skeleton images from Digimorph.org and used with permission.

Figure 2. Melanerpes, a woodpecker in the LRT, nests with dippers, swifts and wrens.

Figure 2. Melanerpes, a woodpecker in the LRT, nests with dippers, swifts and wrens.

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

 

Stilts and hummingbirds: closer than we thought!

Sure,
one has longer legs and probes mud flats (Figs. 1, 2) while the other has tiny legs and probes flowers (Fig. 2), but now they nest close to one another in the large reptile tree (LRT, 1100 taxa, still fully resolved).

Figure 1. Photo and skeletal drawing of Himantopus, the black-necked stilt.

Figure 1. Photo and skeletal drawing of Himantopus, the black-necked stilt. 2 frames GIF movie

 

Himantopus mexicanus (Muller 1776) is the extant black-winged stilt. It is a wading bird with extraordinary long legs. Like the hummingbird, the beak is long and gracile. They eat buried invertebrates in mudflats near water.

Figure 2. Skull of Himantopus mexicanus, the black-winged stilt. Here its hummingbird affinities are apparent.

Figure 2. Skull of Himantopus mexicanus, the black-winged stilt. Here its hummingbird affinities are apparent.

And for comparison,
let’s also look at a hummingbird (Archilochus) skull (Fig. 3), sharing a long list of traits, including a long thin rostrum with a long narrow naris, large cranium and slender, arched prefrontals.

Figure 3. Hummingbird skull for comparison to the stilt in figure 2. Image courtesy of Digimorph.org and used with permission.

Figure 3. Hummingbird skull for comparison to the stilt in figure 2. Image courtesy of Digimorph.org and used with permission.

So roughly the order is:
crows > terns > stilts > hummingbirds. As in so many other novel relationships recovered by the LRT, a bit of googling indicates this hypothetical relationship has not been indicated before. And fantasy confession time: the black-necked stilt is my favorite bird. Knowing that it’s related to hummingbirds makes it all the more intriguing. 

References
Müller OF 1776. Zoologiae Danicae prodromus: seu Animalium Daniae et Norvegiae indigenarum characteres, nomina, et synonyma imprimis popularium. Hafniae, Typiis Hallageriis. 1-274.

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

 

Evolution of the penguin, as told by ancestral taxa

I’m going to let this image tell the story. 

Figure 1. Penguin evolution as told by ancestral taxa back to the Late Jurassic. I could have gone further, but for that see www.ReptileEvolution.com

Figure 1. Penguin evolution as told by ancestral taxa back to the Late Jurassic. I could have gone further, but for that see http://www.ReptileEvolution.com. One of the ways you can tell the LRT is more or less correct is by showing a gradual accumulation of traits for any derived taxon, in this case the penguin. Note the phylogenetic miniaturization prior to the new body plan.

What an image like this does
is to satisfy the eye that all the data points in the large reptile tree (LRT, 1094 taxa) really do add up to a gradual accumulation of traits for any derived taxon, in this case the penguin and all taxa in between. And it’s really going to take the entire Cretaceous and Tertiary to go from Alpha to Omega here. Here (Fig. 1) there are no great morphological gaps. The size changes. The beak length changes. The neck and leg lengths change, but all of this does so gradually, radiating off in different directions every several dozen/thousand generations or whenever the niche changes.

If you need a few more details,
request the .nex file here or run through the referenced taxa, starting with Aptenodytes, the emperor penguin and go backwards… or forwards from Eosinopteryx.

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.