Let’s take out all Solnhofen birds except Archaeopteryx from the LRT

Figure 1. Theropod subset of the LRT focusing on birds and bird mimics. Only one Archaeopteryx, the holotype, nests here with Enantiornithes.

Figure 1. Theropod subset of the LRT focusing on birds and bird mimics. Only one Archaeopteryx, the holotype, nests here with Enantiornithes.

Traditional cladograms include
only one Solnhofen bird, typically labeled Archaeopteryx. Whether they use the holotype specimen or not, I don’t know. Earlier the large reptile tree (LRT, subsets Figs. 1, 2) added several Solnhofen birds, many workers continue to call Archaeopteryx, while others have given new generic names. A recent paper by Wang and O’Connor 2017 on pygostyles brought this subject back to the table. They recovered four different sorts of pygostyles, but did not recognize four convergent origins for the pygostyles due to (I thought at the time) lacking more than one Archaeopteryx specimen. It’s time to test that assertion.

As reconstructions show
the variety of Solnhofen birds has been largely, but not completely overlooked. In any case the variety is certainly apparent and a revision of the genus Archaeopteryx is long overdue given the interest in every new specimen.

So, what happens to the LRT when only one Archaeopteryx (the holotype) is employed?

< See figure 1.
There is no change in the tree topology, other than the loss of six Solnhofen bird taxa (Fig. 2). The holotype Archaeopteryx continues to nest within Enantiornithes, an extinct bird clade.

Taxon deletion is a good test

Figure 2. Subset of the LRT with seven Solnhofen birds included.

Figure 2. Subset of the LRT with seven Solnhofen birds included. Note their basal positions in the several basal bird clades. This chart, by implication, demonstrates that the first birds preceded the Solnhofen Formation.

Having seven Solnhofen birds
in a cladogram illuminates the origin of birds, the origin of enantiornitine birds, the origin of scansoriopterygid birds and the origin of ornithuromorph birds all from Late Jurassic Solnhofen taxa, something we haven’t had until this point. This is what Wang and O’Connor 2017 lacked and so their report on pygostyles was unnecessarily incomplete.

I encourage all bird workers
to include as many Solnhofen birds as possible in their phylogenetic analyses, and for at least one of them (hopefully more) to revise their taxonomy to include more genera. That would make a great PhD thesis.

References
Wang W and O’Connor JK 2017. Morphological coevolution of the pygostyle and tail feathers in Early Cretaceous birds. Vertebrata PalAsiatica 2017:10: 55:3: 1-26.

Zhongornis: NOT the sister taxon of all pygostylians

While we’re on the subject of pygostyles…
Yesterday we looked at a recent paper by Wang and O’Connor (2017) about the evolution of the pygostyle in birds. Reiterating here: Unfortunately Wang and O’Connor did not use several Solnhofen birds (traditional Archaeopteryx specimens) in their analysis. So Wang and O’Connor did not realize the split between the scasoriopterygids, enantiornithes and ornithuromorpha occurred prior to those Late Jurassic Solnhofen long-tailed birds, according to the large reptile tree (LRT, Fig. 2). Thus the pygostyle that developed by convergence several times over. And that fact is pertinent to today’s discussion.

Figure 2. Bird cladogram focusing on Zhongornis. Each of the three colored bird clades independently prodded members with a pygostyle.

Figure 1. Bird cladogram focusing on Zhongornis. Each of the three colored bird clades independently prodded members with a pygostyle. Close observers will note one node within Ornithuromorpha has flipped since yesterday.

 

Which brings us to Zhongornis haoae 
(Fig. 2; D2455 ⁄ 6). Gao et al. 2008 considered their find the sister taxon to all pygostylians. The LRT does not support that nesting because, like Wang and O’Connor, Gao et al. did not use more than one Solnhfoen bird (Archaeopteryx) in their cladistic analysis (Fig. 3) and thus their cladogram was likewise flawed due to taxon exclusion.

Figure 1. Zhongornis. Here DGS finds teeth and a sternum overlooked originally.

Figure 2. Zhongornis. Here DGS finds teeth and a sternum overlooked originally.


So…
Zhongornis
 cannot be the sister-taxon of all pygostylians, contra the assertions of Gao et al. because the pygostyle developed four times by convergence. It stands to reason that no single taxon can be the sister to all four. However, in the LRT Zhongornis does indeed nest at the very base of the Ornithuromorpha between the Archaeopteryx grandis + Confuciusornis and Archaeornithura (Fig. 1).

Among the more derived taxa
are Archaeornithura and Hesperornis both of which do not have a pygostyle.

A more basal taxon,
Sapeornis,
 has a pygostyle and so it represents yet another convergent development within the Ornithuromorpha. Wikipedia reports that Sapeornis is close to Omnivoropteryx, but the LRT does not support that relationship (see Fig. 1) despite similarities such as a perforated deltopectoral crest on the humerus.

Figure 3. The nesting of Zhongornis according to Gao et al. 2008. They did not employ more than one Archaeopteryx specimen, which is the major fault (taxon exclusion) in this cladogram.

Figure 3. The nesting of Zhongornis according to Gao et al. 2008. They did not employ more than one Archaeopteryx specimen, which is the major fault (taxon exclusion) in this cladogram. See figure 1 for an update from the LRT.

According to Gao et al.
Lack of fusion and bone texture indicate the Zhongornis holotype is a juvenile. The femoral heads and necks are not visible, perhaps not yet ossified. Even so, the wing feathers are well-develped, so the specimen is not a hatchling, but close to fledging, according to Gao et al.

Gao et al. report,
“Possessing a unique hand morphology with a phalangeal formula of 2-3-3-x-x and a reduced number of caudal vertebrae lacking a pygostyle the new specimen reveals anatomical information previously unknown and increases the taxonomic diversity of primitive, non-pygostylian birds. We infer from the specimen that during the evolution of the avian tail, a decrease in relative caudal length and number of vertebrae preceded the distal fusion of caudals into a pygostyle.”

Contra the Gao et al. diagnosis

  1. Tiny teeth are apparent in the Zhongornis photo, both on the premaxilla and maxilla. Note that some derived taxa also have tiny teeth. Confuciusornis is toothless but that occurred by convergence from a more basal Late Jurassic split and it represents a sterile lineage.
  2. Zhongornis may not have had a unique manual phalangeal formula. The base of digit 3 is hidden beneath the base of digit 2 (Fig. 4). If other specimens are known that expose this data, please let me know.
  3. A corner of the sternum is visible (Fig. 2) largely beneath the anterior dorsals.
Figure 2. Manus of Zhongornis. The base of digit 3 is hidden behind digit 2.

Figure 4. Manus of Zhongornis. The base of digit 3 is hidden behind digit 2.

Nomenclature issues
Earlier several traditional clades like Ornithodira and Parareptilia were shown to be paraphyletic in the LRT. Now the clade Pygostylia also appears to be paraphyletic when more taxa (in this case more Solnhofen birds) are included.

References
Gao C-L, Chiappe LM, Meng Q-J, O’Connor JK, Wang X, Cheng X-D and Liu J-Y 2008. A new basal lineage of early Cretaceous birds from China and its implications on the evolution of the avian tail. Palaeontology 51(4):775-791.
Wang W and O’Connor JK 2017. Morphological coevolution of the pygostyle and tail feathers in Early Cretaceous birds. Vertebrata PalAsiatica 2017:10: 55:3: 1-26.

Let’s talk about the pygostyle in birds

…because Wang and O’Connor 2017 just wrote a paper on pygostyle evolution.

From their abstract: “The transformation from a long reptilian tail to a shortened tail ending in a pygostyle and accompanied by aerodynamic fanning rectrices is one of the most remarkable adaptations of early avian evolution. All birds with a pygostyle form a monophyletic clade, the Pygostylia (Chiappe, 2002), which excludes only the long bony-tailed birds, Archaeopteryx and the Jeholornithiformes (Jeholornis and kin).”

Key thought from their abstract: “There further exist distinct differences in pygostyle morphology between Sapeornithiformes, Confuciusornithiformes, Enantiornithes, and Ornithuromorpha.”

Figure 1. Flawed theropod cladogram according to Wang and O'Connor 2017 based on Brusatte 2014.

Figure 1. Flawed theropod cladogram according to Wang and O’Connor 2017 based on Brusatte 2014. This cladogram suffers from taxon exclusion and so tells us little about pygostyle evolution.  Only one clade here has a pygostyle. See figure 2 for more data.

Wikipedia reports, “The pygosylians fall into two distinct groups with regard to the pygostyle. The Ornithothoraces have a ploughshare-shaped pygostyle, while the more primitive members had longer, rod-shaped pygostyles. The earliest known member of the group is the enantiornithine species Protopteryx fengningensis, from the Sichakou Member of the Huajiying Formationof China, which dates to around 131 Ma ago,”

Figure 2. Subset of the LRT focusing on derived theropods. Those with a pygostyle are colored.

Figure 2. Subset of the LRT focusing on derived theropods. Those with a pygostyle are colored. Among birds, gray taxa have a distal fusion, as do other very derived non-bird taxa, some of which are not included here. Wnag and O’Connor apparently did not test several Solnhofen birds and so did not understand the basal division of bird clades that occurred  among the ‘Solnhofen birds’  shown here.

 

Wang and O’Connor correctly note
that some derived therizinosaurs and ovitrapotorsaurs have distal caudal vertebrae that are fused after a long string of unfused verts. Not correctly they consider this the first of many evolutionary steps toward the completely fused pygostyle of extant birds. A subset of the large reptile tree (LRT, figure 2) documents three origins for the pygostyle in Avialan taxa and a few other aborted attempts in other clades.

If only Wang and O’Connor
had used a half-dozen Solnhofen birds (they can’t ALL be Archaeopteryx) in their study they would have found the multiple convergent evolution of the pygostyle in basal Aves. Once again, taxon exclusion is keeping the blinders on paleontologists.

Wang and O’Connor do not recover
Sapeornis as a basal Ornithourmorph. The write: “Despite published diversity, the Sapeornithiformes is considered a monospecific clade with all taxa referable to Sapeornis chaoyangensis.

Wang and O’Connor were very interested in
Caudipteryx, traditionally considered a basal member of the Oviraptorosauria. It now nests with Limusaurus, or closer yet, the ‘juvenile’ Limusaurus, a sister to the oviraptorid, Khaan. It lacks a pygostyle, but has a fan of tail feathers.

Wang and O’Connor conclude “Fusion or partial fusion of the terminal caudal vertebrae in maniraptorans is observed in the Therizinosauroidea, Oviraptorosauria and potentially also the Scansoriopterygidae. However, morphological differences between these phylogenetically separated taxa indicate these co-ossified structures cannot be considered equivalent to the avian pygostyle. Outside the Ornithuromorpha, no group preserves evidence of a tail complex.”

Scatter diagrams of pygostyle traits provided by Wang and O’Connor
(their figure 7) also show four clades of rarely and then barely overlapping data. The vast majority is non-overlapping data as the pygostyle really did evolve several times within Aves.

Notably the bird mimics
Microraptor and Sinornithosaurus, both closer to T-rex and Orinitholestes than to birds, have no trace of a pygostyle.

References
Chiappe LM 2002. Basal bird phylogeny: problems and solutions. In: Chiappe L M, Witmer L eds. Mesozoic Birds: Above the Heads of Dinosaurs. Berkeley: University of California Press. 448–472.
Wang W and O’Connor JK 2017. Morphological coevolution of the pygostyle and tail feathers in Early Cretaceous birds. Vertebrata PalAsiatica 2017:10: 55:3: 1-26.

wiki/Pygostylia

Jurassic birds took off from the ground – SVP abstracts 2016

Everyone knows:
Ground up hypothesis – 

implies and includes flapping, always has. Birds flap, always have, at least since the elongation and locking down of the coracoid in ancestral troodontids.

Trees down hypothesis –
has always implied gliding. Gliders don’t flap, never have.

But
baby birds dropping out of trees always flap. It’s what they do. But that fact is often ignored in bird origin videos.

And, as everyone knows by now…
young birds with pre-violant wings flap them like crazy when climbing bipedally — even vertical tree trunks… also something several animated bird origin videos ignore, perhaps because of one glaring opposite extant example: the young wet hoatzin that struggles to climb with all four limbs.

With that preamble…Habib et al. 2016 provide us
a hypothesis on the origin of bird flight that appears to ignore trees and experimental work with pre-volant birds and goes straight to take-off from flat ground. Is that okay?

From the abstract:
“Many small non-avian theropods possessed well-developed feathered forelimbs, but questions remain of when powered flight evolved and whether it occured more than once within Maniraptora. Here, using a first principles modeling approach, we explore these questions and attempt to determine in which taxa takeoff and powered flight was possible. Takeoff is here defined as a combination of both the hindlimb driving the ballistic launch phase, and the wing-based propulsion (climb out). [1]

“Microraptor, Rahonavis, [2] and all avian specimens generated sufficient velocity during leaping or running for takeoff. We re-ran our analysis factoring in life history changes that can alter the flight capability in extant avians, such as egg retention and molting, to examine how these would influence take off capacity. Of the two, molting shows the most significant effects.

“When these results are coupled with work detailing the lack of arboreal features among non-avian maniraptorans and early birds, they support the hypothesis that birds achieved flight without a gliding intermediary step, something perhaps unique among volant tetrapod clades.” [3] [4] [5]

Figure 2. Cosesaurus running and flapping - slow.

Figure 1. Cosesaurus running and flapping – slow.

Notes

  1. Interesting that Habib et al. ignore the presence of trees, which are key to Dial’s hypothesis (updated in Heers et al. 2016)  and opts to go straight from ground to air. That kind of ignores key work, doesn’t it? You might recall that Dr. Habib became famous as the author of the infamous but popular forelimb quad launch hypothesis for pterosaurs.
  2.  Microraptor and Rahonavis are NOT in the lineage of birds in the LRT, but both show how widespread long feathered wings were in Theropoda. The former has elongate coracoids by convergence. The latter does not preserve coracoids, fingers or feathers, but does have the long forearm that might imply bird-like proportions for missing bones… or not.
  3. Apparently Habib et al. assume that pterosaurs and bats originated as gliders when present largely ignored evidence indicates exactly the opposite. Cosesaurus (Fig. 1) was a pterosaur precursor with elongate coracoids, unable to fly, but able to flap. Bats rarely glide, so it is unlikely that they did so primitively. Lacking coracoids, bats employ elongate clavicles to anchor flight muscles.
  4. Okay, so remember the preamble (above) about gliding and trees. When Habib et al. bring up ‘a gliding intermediary step‘, they are implying the presence of trees (high places) in competing and validated-by-experiment hypotheses for the origin of bird flight  — which they are ignoring. They also ignore the fact that baby birds don’t glide when they fall out of trees. They flap like their lives depend upon it. I find those omissions odd, but its not the first time pertinent work has been ignored in paleontology.
  5. In the LRT Xiaotingia (Fig. 2) is the most primitive bird-like troodontid to have elongate coracoids and so may have been the first flapper in the lineage.
Figure 1. Xiaotingia with new pectoral interpretation. See figure 3 for new tracing.

Figure 2. Xiaotingia with new pectoral interpretation.

References
Habib M, Dececchi A, Dufaault D and Larsson HC 2016. Up, up and away: terrestrial launching in theropods. Abstract from the 2016 meeting of the Society of Vertebrate Paleontology.
Heers AM, Baier DB, Jackson BE & Dial  KP 2016. 
Flapping before Flight: High Resolution, Three-Dimensional Skeletal Kinematics of Wings and Legs during Avian Development. PLoS ONE 11(4): e0153446. doi:10.1371/journal.pone.0153446
http: // journals.plos.org/plosone/article?id=10.1371/journal.pone.0153446

YouTube video showing birds running up tree trunks while flapping with nonviolent wings

ScienceNews online promo.

Stinkbird on steroids = Gastornis!

Figure 1. Gastornis (Diatryma) was a large bird of the late Paleocene,/early Eocene. It appears to share many traits withy the living hoatzin, Opisthocomus.

Figure 1. Gastornis (Diatryma) was a large bird of the late Paleocene,/early Eocene. It appears to share many traits withy the living hoatzin, Opisthocomus. Pedal digit 1 was likely retroverted.

Adding
giant Gastornis (Diatryma) (Fig. 1) to the large reptile tree brings to mind an old Warner Bros. Tweetybird/Sylvester cartoon, nicknamed on YouTube, “Tweety on Steroids” (Fig. 1).

I could not help noticing
a long list of synapomorphies shared between the giant flightless Paleocene bird, Gastornis, with the living stink bird, more commonly known as the hoatzin, Opisthocomus hoazin. The nickname ‘stink bird’ comes from its smell, derived from the rotting vegetation of its herbivorous diet. In Gastornis, a lack of sharp talons, a lack of a hooked beak together with its heavy bones and large gut indicate an herbivorous diet as well.

Figure 1. Warner Bros. cartoon on YouTube (click to view) transforms little Tweety into a giant monster, like Gastornis.

Figure 1. Warner Bros. cartoon on YouTube (click to view) transforms little Tweety into a giant monster, like Gastornis.

A comparison to Opisthocomus 
(Fig. 2) is interesting, and will follow, but perhaps more interesting, Gastornis shares several traits with non-avian dinosaurs, evident atavisms, not visible on known sister taxa.

Figure 2. The hoatzin, Opisthocomus, skeleton is quite similar to that of Gallus, the chicken. Juveniles do not have fused fingers.

Figure 2. The hoatzin, Opisthocomus, skeleton is quite similar to that of Gallus, the chicken. Juveniles do not have fused fingers.

Like non-avian dinosaurs, Gastornis has

  1. complete upper temporal arch (postorbital + squamosal)
  2. orbit not confluent with temporal fenestrae
  3. orbit taller than wide
  4. postfrontal
  5. ribs without uncinate processes
  6. lack of fused dorsal vertebrae
  7. coracoid approaching disc-like
  8. orbit shorter than postorbital skull length
  9. maxilla taller than 40% orbit height
  10. jugal with elongate qj process, short suborbital portion
  11. parietal skull table not broad, weakly constricted
  12. occiput close to quadrates
  13. ilium posterior process longer than anterior process (also as in Struthio and Hesperornis)
Figure 3. Gastornis (Diatryma) skull model with bones identified.

Figure 3. Gastornis (Diatryma) skull model with bones identified.

Like Opisthocomus, Gastornis has

  1. nasals connect medially
  2. descending jugal
  3. large gut/herbivorous diet
  4. dentary contributes to coronoid
  5. mandibular fenestra
  6. mandible ventral shape: 2 tier convex

References
Cope ED 1876. On a gigantic bird from the Eocene of New Mexico. Proceedings of the Academy of Natural Sciences of Philadelphia 28 (2): 10–11.
Matthew WD, Granger W and Stein W 1917. The skeleton of Diatryma, a gigantic bird from the Lower Eocene of Wyoming. Buletin of the American Museum of Natural History, 37(11): 307-354.
Hébert E 1855a. Note sur le tibia du Gastornis pariensis [sic] [Note on the tibia of G. parisiensis]. C. R. Hebd. Acad. Sci. Paris (in French) 40: 579–582.
Hébert E 1855b. Note sur le fémur du Gastornis parisiensis [Note on the femur of G. parisiensis]. C. R. Hebd. Acad. Sci. Paris (in French) 40: 1214–1217.
Prévost C 1855. Annonce de la découverte d’un oiseau fossile de taille gigantesque, trouvé à la partie inférieure de l’argile plastique des terrains parisiens [Announcement of the discovery of a fossil bird of gigantic size, found in the lower Argile Plastique formation of the Paris region]. C. R. Hebd. Acad. Sci. Paris (in French) 40: 554–557.
Statius Müller PL 1776. Des Ritters Carl von Linné Königlich Schwedischen Leibarztes &c. &c. vollständigen Natursystems Supplements- und Register-Band über alle sechs Theile oder Classen des Thierreichs. Mit einer ausführlichen Erklärung. Nebst drey Kupfertafeln.Nürnberg. (Raspe).

wiki/Hoatzin
wiki/Gastornis

Paleocene birds

Curious about
the distribution of Paleocene birds, I found a list online and applied it to a globe image (Fig. 1). The Chicxulub impact is added along with its projected ejecta area north to Montana.

Figure 1. The world at the K-T boundary, 65 mya and the distribution of Paleocene birds.

Figure 1. The world at the K-T boundary, 65 mya and the distribution of Paleocene birds. Click to enlarge.

I wondered if the distribution of birds in the Paleocene
reflected some kind of expansion from a refuge, perhaps at the antipodes to the asteroid impact. The answer is ‘no.’

The data shows
that Paleocene birds are found worldwide, with most specimens located in North America and Europe, close to the impact site and close to most paleontologists. How these birds survived when all others did not remains a mystery. If there was an initial refuge at the antipodes, these birds quickly spread out from that zone leaving no clue to their origin.

Figure 2. The hoatzin, Opisthocomus, skeleton is quite similar to that of Gallus, the chicken. Juveniles do not have fused fingers.

Figure 1. The hoatzin, Opisthocomus, skeleton is quite similar to that of Gallus, the chicken. Juveniles do not have fused fingers.

Figure 1. Skull of the hoatzin (Opisthocomus) with bones colorized.

Figure 2. Skull of the hoatzin (Opisthocomus) with bones colorized.

Among living birds
the hoatzin, Opisthocomus hoazin, (Müller 176) a 65cm herbivorous tropical bird from the Amazon, is often considered one of the most primitive of living birds, largely because juveniles have the atavism of individual clawed fingers that fuse upon reaching adulthood.

In the large reptile tree, which includes only three living birds, Opisthocomus nests with Gallus, the chicken. Obviously that will change when more taxa are added, but the overall resemblance is basic.

Wikipedia reports:
“Cladistic analysis of skeletal characters, on the other hand, supports a relationship of the hoatzin to the seriema family Cariamidae, and more distantly to the turaco and cuckoo families.”

Other studies conflict
with those results. Bird phylogenetic studies often do not agree with one another. This may be due to massive convergence based on huge taxon lists.

Hoatzins are currently the only members
of the clade Opisthocomidae and the order Opisthocomiformes. Wikipedia nests them within the Passerea then within the Neoaves, not close to Gallus. Neoaves include all living birds except Paleognathae (ratites and kin) and Galloanserae (ducks, chickens and kin = Fowl).

In Opisthocomus
the feet are large, the premaxilla does not reach the frontals, the nasals are robust, the upper temporal fenestra is located laterally, below the ‘equator’ of the expanded braincase and the sternum is deep.

The other primitive living bird is
one of several tinomous. Here (Fig. 3) the tinamou, Rhynchotus, was added to the large reptile tree. It nests with Struthio (Fig. 5), but shares many traits with Gallus and Opisthocomus.

Figure 4. Rhynchotus is a genus in the basal bird family of Tinamiformes. They are related to living large flightless birds. Note the small feet. 

Figure 4. Rhynchotus is a genus in the basal bird family of Tinamiformes. They are related to living large flightless birds. Note the small feet, like Struthio, figure 5.

Figure 4. Struthio, the ostrich, is currently a sister to the tinamou, Rhynchotus.

Figure 5. Struthio, the ostrich, is currently a sister to the tinamou, Rhynchotus.

I’d be curious to know
which genera crossed the K-T boundary?

References
Statius Müller PL 1776. Des Ritters Carl von Linné Königlich Schwedischen Leibarztes &c. &c. vollständigen Natursystems Supplements- und Register-Band über alle sechs Theile oder Classen des Thierreichs. Mit einer ausführlichen Erklärung. Nebst drey Kupfertafeln.Nürnberg. (Raspe).

wiki/Hoatzin

 

 

2015 SVPCA abstract supports troodontid-bird clade

Nice to get confirmation
for a subset of the large reptile tree in a SVPCA poster (Brougham 2015).

From the Brougham results:
“The modified matrix strongly supports a Troodontidae + Avialae clade rather than a monophyletic Deinonychosauria, a topology remarkably convergent on that seen in modified Godefroit phylogeny, in which Aurornis, Eosinopteryx and the Tiaojishan paravians form a sister clade to Anchiornis and more derived avialans, the two of which in turn form a sister clade to Troodontidae.”

Figure 1. Basal theropod subset of the large reptile tree showing troodontids basal to birds and separate from dromaeosaurs.

Figure 1. Basal theropod subset of the large reptile tree showing troodontids (light red) basal to birds (red) and separate from dromaeosaurs (white).

References
Brougham T 2015. Multi-matrix analysis of new Chinese feathered dinosaurs supports troodontid-bird clade. researchgate.net/publication/280728942