Palaeotis, a tiny Eocene flightless ostrich

Figure 1. Nearly proportioned like its giant descendant, Palaeotis was an Eocene ostrich less than 1/3 as tall.

Figure 1. Nearly proportioned like its giant descendant, Palaeotis was an Eocene ostrich less than 1/3 as tall. Evidently there were larger specimens of the larger winged Palaelodus, but I can only find data for this one at present.

Paelotis weigelti (Lambrecht 1928; middle Eocene; GM 4362) was originally described as an extinct bustard, like Ardeotis. Later (Houde and Haubold 1987) it was referred to the ostrich clade. The wings are small, but the sternum remains large on Paelotis. The pelvis has not attained its larger posterior size yet. Those portions anchor powerful leg muscles on the Struthio, the ostrich. The skull was similar in most respects, but was proportionately larger, like that of a juvenile ostrich. As in Struthio, the scapulocoracoid is fused. The femur was relatively longer. Three toes were present.

Figure 2. Palaeotis untangled, placed into an in vivo pose. Not sure how many pedal digits were present.

Figure 2. Palaeotis untangled, placed into an in vivo pose. Pedal digit 2 is not shown. Note the long humerus and short antebrachium. The bill remains relatively narrow. The sternum remains big.

Figure 3. Palaeotis in situ.

Figure 3. Palaeotis in situ. Note the short right metatarsus. The proximal part must be dislocated beneath the tibia.

References
Houde P and Haubold H 1987. Paleotis weigelti  restudied: a small middle Eocene ostrich (Aves: Struthioniformes) Palaeovertebrata, Montpellier 17(2):27–42.
Lambrecht K 1928. Palaeotis weigelti n. g. sp., eine fossil trappe aus der mitteleozanen Braunkohle des Geiseltales. Jahrbuch hallesch. Verband., Halle, n.s., 7:11.

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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

The second half of neornithine evolution

Revised January 08, 2018 with a revised cladogram.

Generally
cladograms have no trouble nesting closely-related, highly-derived sisters. The trouble shows up when you try to find out how basal clades are related. Sometimes bird cladograms look more like combs than ladders or bushes. Not a problem here in the fully resolved large reptile tree (LRT, 1145 taxa, subset Fig. 1).

Here
the Neornithes is basically halved (given presently tested taxa) at the grackle/crow/blue jay (Quiscalus/Corvus/Cyanocitta) clade. Here the descendants of an unknown prehistoric grackle represent the second half of neornithine evolution. Most, but not all, of those basal taxa have a bigger bill. Most, but not all, have longer legs. The picture stays about this fuzzy until more taxa are added. But this cladogram lumps and splits verifiable relationships better than prior ones.

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.

What follows
includes a wide variety of taxa. Here only basal forms are illustrated.

Quiscalus quiscula (Linneaus 1758 ) is the common grackle, what one might consider a fairly typical bird, but it is phylogenetic miniature of its ancestors, the long-legged screamers (Anhima and Chauna). And it’s a better flyer.

Scopus umbretta (Brisson 1760, 56 cm tall) is the extant hamerkop. Basically this is a dull, long-legged grackle with a long narrow bill (Fig. 2). In the LRT the hamerkop nests basal to the shoebill and pelican (Pelecanus), petrels (Macronectes), auks, puffins, New World vultures (Coragyps) and their descendants the dodo and solitaire.

Pteroglossus aracari (Linneaus 1758) is the extant black-necked aracari, a type of toucan. Basically this a grackle with a giant bill. Here toucans are related to Old World hornbills and worldwide barbets. 

Threskiornis aethiopicus (Latham 1790, 68 cm long) is the extant sacred ibis. Basically this is a wading grackle. It has a narrow, down-curved beak. It nests basal to the spoonbill (Platalea) and duck (Anas) clade. Unfortunately, that missing link remains missing.

Aramus guarauna (Linneaus 1766) is the extant limpkin. Basically this another long-legged wading grackle. Congeneric specimens of this derived taxon are found in the Miocene.The limpkin is often considerd transitional between rails and cranes, but here nests basal to wide variety of birds: sea gulls, terns, hummingbirds, penguins, woodpeckers, dippers, wrens and pigeons.Smaller bills represent phylogenetic miniaturization. Such variety argues for a deeper origin of neornithes, despite the lack fossils in the Cretaceous.

Figure 2. Quiscalus and its descendants, Scopus, Aramus, Threskiornis and Pteroglossus.

Figure 2. Quiscalus and its descendants, Scopus, Aramus, Threskiornis and Pteroglossus. Note the gradual retraction of the naris.

When we talk about the gradual accumulation of traits
this is how that manifests itself with available taxa. Before these taxa had descendants that evolved into so many different phenotypes, these five were sisters that took the grackle bauplan and tweaked it one way and another and another world wide.

 

Patagopteryx: turning back the genetic clock on pedal digit 1?

We’ve seen reversals before
in theropod dinosaurs. Remember Limusaurus re-developing a digit zero? And what a fuss it made with regard to theropod/bird finger homology? Nobody else considered the possibility that an ancient gene could switch on again and add a digit medial to digit one. But that was the best explanation after phylogenetic analysis.

Figure 1. The two-toed ostrich (Struthio) nests with the four-toed Patagopteryx, when all relatives have only three toes.

Figure 1. The two-toed ostrich (Struthio) nests with the four-toed Patagopteryx, when all relatives have only three toes. Note the pubic foot. 

Here’s an apparent new reversal
Patagopteryx (Alvarenga and Bonaparte 1992, Late Cretaceous) was a flightless bird that currently nests with the ostrich, Struthio, with which it shares a long list of traits (Fig. 1). Except it has at least one extra toe (Fig. 1). All currently tested palaeognath birds, including tinamous, have only three toes. Patagopteryx is the oldest known clade member, at 80 mya. 

Figure 2. Ventral view of the pes of Patagopteryx. Digits numbered. Pedal digits 1 and 5 are not present in other palaeognaths.

Figure 2. Ventral view of the pes of Patagopteryx. Digits numbered. Pedal digits 1 and 5 are not present in other palaeognaths.

Did other palaeognaths lose pedal digit 1
several times by convergence? Or did Patagopteryx regrow pedal digit 1 in another case of reversal? Would it matter to your decision that pedal digit 1 is not reversed for perching, as it appears in slightly more distant ancestors, like Archaeornithura and Confuciusornis? Does it matter that Patagopteryx is at least 80 million years old?

The scores say the toe reappeared,
but I think the age of Patagopteryx trumps that. Pedal digit 1 was oriented anteriorly in Late Jurassic Solnhofen birds and Early Cretaceous neornithes, like Longicrusavis (Fig. 3).

Figure 2. It's always valuable to see what the taxon looks like with scale bars. This is a tiny specimen, but rather completely known.

Figure 3. It’s always valuable to see what the taxon looks like with scale bars. This is a tiny specimen, but rather completely known. Pedal digit 1 may not be retroverted in this taxon. The proximal phalanxes may have been elevated here. 

The key takeaway here
is similar to what pilots say when they enter a cloud, “Trust your instruments.” In this case, trust your phylogenetic analysis. Sometimes autapomorphies pop up. Study them and, if you have to, accept them.

References
Alvarenga and Bonaparte 1992. A new flightless land bird from the Cretaceous of Patagonia; pp. 51–64 in K. E. Campbell (ed.), Papers in Avian Paleontology, Honoring Pierce Brodkorb. Natural History Museum of Los Angeles County, Science Series 36.
Chiappe LM 2002. Osteology of the flightless Patagopteryx deferrariisi from the late Cretaceous of Patagonia (Argentina) pp.281–316 in Mesozoic Birds, Above the Heads of Dinosaurs, Chapter: 13, Editors: Chiappe LM and Witmer LM, University of California Press.

wiki/Patagopteryx

Monias: Roadrunner or Pigeon?

It’s pretty obvious at first glance…
(Fig. 1) but Prum et al. 2015, using phylogenomic analysis, says Monias might look like a roadrunner from Madagacar, but it’s really a pigeon on the inside.

I’m starting to hate DNA sequencing
more and more each day for the insanity it recovers. Let’s all just admit that DNA analysis in taxonomy needs to go by the wayside as a historical curiosity that only muddles understanding of the small steps evolution takes to create new taxa.

Figure 1. The sub desert mesite, Monias benschi. Prum et al. nest it with pigeons. The LRT nests it with cuckoos like the roadrunner.

Figure 1. The sub desert mesite, Monias benschi. Prum et al. nest it with pigeons. The LRT nests it with cuckoos like the roadrunner.

For that matter
(and forgive me for ranting) but why can’t we get consensus on the family tree of Neoaves?

Bird experts Mayr and Clarke (2003) may have said it best:
“Consensus is elusive regarding the phylogenetic relationships among neornithine (crown clade) birds.” 

Four years later,
bird experts Livezey and Zusi (2007) wrote: “it is also clear that many phylogenetic problems have proven resistant to all attempts at solution and seem destined to controversy.”

Eight years after that,
bird experts Prum (2015) wrote: “The evolutionary history of Neoaves—a clade that encompasses nearly all living bird species—remains the greatest unresolved challenge in dinosaur systematics.”

This is what you learn
when you start expanding your interests and reading the literature on the unfamiliar taxa in your library. Lucky thing this is science, where anyone can put some characters and taxa together to figure out what things are.

Prum et al. used phylogenomic analysis
(gene sequencing) to determine that the extant desert mesite (Monias breschi, Fig. 1) is a pigeon relative. And that wasn’t their only gene-based unchecked mistake.

By contrast
the large reptile tree (LRT) nests Monias with the cuckoos, Coccyzus and Geococcyx. The latter is more famously known as the American roadrunner. Monias would be its Madagascan counterpart. That long down curving beak is a trait found in this clade, greatly emphasized in Monias. It picks insects, seeds and fruit off the scrubby desert floor.

References
Prum, R. O. et al. 2015. A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing. Nature 526, 569–573.

wiki/Subdesert_mesite

Grebes break the rules

Figure 1. Grebe mating ritual: walking on water.

Figure 1. Grebe mating ritual: walking on water.

Grebes really do break some of the most basic rules.
Not content to be excellent divers, also capable of flying, they also like to walk on water. Click here for a YouTube video narrated by David Attenborough.

Figure 2. Another miracle: a grebe walking bipedally.

Figure 2. Another miracle: a grebe walking bipedally.

Analogous to, but not directly related to
Late Cretaceous hesperornithids with a similar front-heavy build, somehow grebes are able to walk bipedally (Fig. 2). So long as one toe is in front of the center of gravity, all is well.

Figure 3. Loon skeleton with femur (yellow) and tibia/patella (green) highlighted. In this mount the center of gravity is in front of the toes, which makes this an untenable mount, unless the loon is floating on water.

Figure 3. Loon skeleton with femur (yellow) and tibia/patella (green) highlighted. Note the splayed hind limbs, very different from most dinosaurs. Yet, somehow, as in pterosaurs, the splayed femur supports an erect hind limb. What is missing from the photograph? Hint: It should be on the far right edge. And what a big kneecap this one has!!

Why do some books say
dinosaurs have an erect femur? Here’s an exception or two. The grebe and the loon definitely do not have an erect femur (Fig. 3). Rather the femur sprawls, like that of a lizard or any one of several pterosaurs. Yet somehow the sprawling femur does not prevent an erect hind limb.

Why do some books say
birds have a pygostyle (fused terminal tail bones)? Evidently grebes did not get the memo. Click this link. It will take you to a wonderfully mounted Western grebe skeleton that appears to lack a pygostyle (toward the middle of the webpage).

Pandion, the osprey, joins the LRT

And the osprey,
Pandion haliaetus (Linneaus 1758) joins the large reptile tree (LRT, 1124 taxa) at the base of (owls + swifts) + (Old World vultures + falcons). The secretary bird, Sagittarius, and the terror birds are proximal outgroups.

Figure 1. Pandion, the osprey, nests at the base of the birds of prey, sans the secretary bird and seriema.

Figure 1. Pandion, the osprey, nests at the base of the birds of prey, sans the secretary bird and seriema.

So the osprey is a basal
short-legged, arboreal birds-of-prey.

Wikipedia reports,
“The osprey differs in several respects from other diurnal birds of prey. Its toes are of equal length, its tarsi are reticulate, and its talons are rounded, rather than grooved. The osprey and owls are the only raptors whose outer toe is reversible, allowing them to grasp their prey with two toes in front and two behind. It has always presented something of a riddle to taxonomists, but here it is treated as the sole living member of the family Pandionidae, and the family listed in its traditional place as part of the order Falconiformes.”

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.

wiki/Osprey