The origin of giant birds: Gastornis (Diatryma), the giant parrot

Earlier we talked about the giant Gastornis as the sister to the parrot, Ara in the large reptile tree (LRT, 1119 taxa). Traditionally workers considered Gastornis a giant goose. Not sure why… unless they never tested Gastornis with parrots.

But first
let’s take a look at a recent paper on parrot origins, Wright et al. 2008. I came by this study while looking for fossil parrots, especially those without a descending beak tip. I did not find any. The Wright et al. study found an Australasia origin for the clade during the Cretaceous without any close relationships among modern birds.

That last conclusion is, of course, unacceptable and illogical. 
Here’s the problem: Wright’s team chose Falconiformes (Falcons), Columbiformes (pigeons and doves), Cuculiformes (cuckoos), Piciformes (woodpeckers), Coraciiformes (kingfishers), Strigiformes (owls), and Coliiformes (mousebirds) as outgroups because each was considered an ally or sister of parrots at one time or another in recent molecular phylogenetic work.

Therein lies the answer to the problem.
The large reptile tree (LRT, 1119 taxa) based on morphology nests all of these taxa far from parrots, a clade that nests with the hoatzin (Opisthocomus), the sparrow (Passer) and the chicken (Gallus) in order of increasing distance. DNA does not work over large phylogenetic distances ~ especially when sister taxa are excluded from the analysis!!

On a similar note
Bourdon and Cracraft 2011, nested Gastornis deep within the terror birds, which they mistakenly labeled, the Cariamae. I say mistakenly because the seriema, Cariama, is more closely related to flamingoes than to terror birds in the LRT, as reported earlier. This is where a wide gamut study, like the LRT, comes in handy. If Gastornis were truly a terror bird, it would have nested with them in the LRT.

Readers,
don’t guess, imagine or follow tradition or your professors when choosing your taxon list. Let an overarching study, like the LRT, guide you in your selection.

Now, on to our main topic…

Figure 1. Gastornis (=Diatryma) to scale with Ara the parrot (lower right).

Figure 1. Gastornis (=Diatryma) to scale with Ara the parrot (lower right).

Ara macao (Linneaus 1758; extant ) is the scarlet macaw. Here it nests with the giant Eocene parrot, Gastornis in the LRT. Both are among the few birds that separate the orbit from the temporal fenestrae. In parrots digit 4 (mislabeled above) extends posteriorly along with digit 1. This happens by convergence in several clades, btw.

Figure 3. Skulls of Gastornis, Brontornis and Ara, the scarlet macaw.

Figure 3. Skulls of Gastornis, Brontornis and Ara, the scarlet macaw. Ara is not to scale. Brontornis is another giant parrot known from a mandible, a metatarsus and little else.

Gastornis parisiensis (Hebert 1855, Matthew et al. 1917) is one of several species, including G. (formerly Diatryma) gigantea. Derived from a sister to Opisthocomus, the hoatzin, Gastornis nests as a sister to Ara. Likely an herbivore, Gastornis had vestigial forelinmbs, cursorial hind limbs and redeveloped an upper temporal fenestra with an enlarged postfrontal, postorbital and squamosal, as in parrots. The rostrum is chiefly composed of the premaxilla, as in parrots.

Figure x. Bird giants in the bird subset of the LRT.

Figure 4. Bird giants in the bird subset of the LRT.

References
Bourdon E and Cracraft J 2011. Gastornis is a terror bird: New insights into the evolution of the cariamae (Aves, Neornithes). Society of Vertebrate Paleontology 71stAnnual Meeting Program and Abstracts, p. 75
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.
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.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
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.
Owen R 1843. On the remains of Dinornis, an extinct gigantic struthious bird. Proceedings of the Zoological Society of London: 8–10, 144–146.
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.
Wright TF, et al. (ten co-authors) 2008. A Multilocus Molecular Phylogeny of the Parrots (Psittaciformes): Support for a Gondwanan Origin during the Cretaceous. Molecular Biology and Evolution, 25 (10), 2141-2156 DOI: 10.1093/molbev/msn160.

 

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The origin of giant birds: Dinornis, the giant hoatzin

There have been several giant birds
in the fossil record (Fig. 1), and a few, like the ostrich, Struthio, are still alive today. In the next few days we’ll examine several giant birds and their smaller progenitors.

Figure 1. Giant Dinornis compared to chicken-sized Opisthocomus to scale and similar in torso length.

Figure 1.
Giant Dinornis compared to chicken-sized Opisthocomus to scale and similar in torso length.

Dinornis, the giant hoatzin
Dinornis maximus (Owen 1843; recently extinct; 3.6m tall), the moa, is the tallest bird that ever lived. Females were apparently distinct and larger than males. Long considered a ratite based on its resemblance to Struthio, the ostrich, here in the large reptile tree (LRT, 1119 taxa, subset Fig. 3) Dinornis nests between the hoatzin, Opisthocomus (see below) and parrots like Ara. Feather color was similar to the hoatzin, but perhaps more hair-like in substance.

Opisthocomus hoazin (Müller 1776, Hoatzin) The extant hoatzin, or stink bird, is a chiefly arboreal bird capable of short flights. A sister to Gallus and DinornisOpisthocomus is famous for having chicks with claws on two of the wing digits that metamorphosize into the standard fused bird hand as adults. This appears to be an atavism, or reappearance, of a trait that is lost in all other birds. The hoatzin is an herbivore. The feet are large. The taxonomic positiion of Opisthocomus has been debated, but it appears to be a primitive member of extant birds, close to the much larger Dinornis (below).

Here, another big flightless bird:

Figure 3. The extinct and flightless Cnemiornis (at right) compared to the extant and volant Cereopsis, the New Zealand goose.

Figure 2. The extinct and flightless Cnemiornis (at right, note the little forelimbs) compared to the extant and volant Cereopsis.

This is Cnemiornis
(Fig. 3, right; Owen 1866; recently extinct; 1 m tall), the New Zealand goose, a very large and flightless goose with reduced forelimbs, reduced sternum and not much webbing between the toes. The neck is longer and pedal digit 1 is absent.

As in the unrelated Dinornis, relative to Opisthocomus,
the skull is relatively smaller, the neck is longer and has more cervicals, the dorsal neural spines are taller, the pelvis is less ossified, the forelimbs are vestiges, the patella is larger, and pedal digit 1 is smaller (actually absent in Cnemiornis).

Figure x. Bird giants in the bird subset of the LRT.

Figure 3. Bird giants in the bird subset of the LRT.

References
Owen R 1843. On the remains of Dinornis, an extinct gigantic struthious bird. Proceedings of the Zoological Society of London: 8–10, 144–146.
Owen R 1866. XI. On Dinornis (Part X.): containing a Description of part of the Skeleton of a flightless Bird indicative of a New Genus and Species (Cnemiornis calcitrans, Ow.) Journal of Zoology 1866 The Zoological Society of London.
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/Dinornis
wiki/Cnemiornis

A little cleanup in the bird cage, er, I mean, bird clade

Birds, as I’ve said before,
and as everyone agrees, are difficult to manage in a cladogram. But not impossible. As I learn about taxa, earlier mistakes are corrected.

Figure 1. Septencoracias, earlier nested with kingfishers, now nests with barbets, like Psilopogon in figure 2. Note the posteriorly drooping maxilla.

Figure 1. Septencoracias, earlier nested with kingfishers, now nests with barbets, like Psilopogon in figure 2. Note the posteriorly drooping maxilla.

First up
Septencoracias morsensis (Bourdon et al., 2016; Eocene 54mya; 25 cm length; Fig. 1) is an extinct barbet, not a kingfisher, as originally identified. A tiny claw remained on manual digit 1. Note the strong resemblance to Psilopogon with the concave maxilla extending below the dentary laterally.

Figure 2. Skull of the extant barbet, Psilopogon. Note the posteriorly drooping maxilla and compare it to Septencoracias in figure 1.

Figure 2. Skull of the extant barbet, Psilopogon. Note the posteriorly drooping maxilla and compare it to Septencoracias in figure 1.

Psilopogon pyrolophus (S. Müller 1836; 28 cm in length; SE Asia) is the extant fire-tufted barbet. This frugivore resides at the base of toucans + hornbills and it uses tree cavities to nest and raise chicks in.

Figure 1. Chroicocephalus, the black-headed sea gull in vivo and as a skeleton.

Figure 2. Chroicocephalus, the black-headed sea gull in vivo and as a skeleton.

Second
sea gulls, like Chroicocephalus, move a little closer to hummingbirds, though still not far from kingfishers, penguins and dippers in the large reptile tree (LRT, 1119 taxa). 

Figure 3. Bird subset of the LRT showing changes mentioned above.

Figure 3. Bird subset of the LRT showing changes mentioned above. Note: Aepyornis now nests with Struthio.

Chroicocephalus ridibundus (Linneaus 1766; 40cm long; Fig. 2) is the extant black-headed gull. It was previously listed as the genus Larus and is a gregarious, opportunistic omnivore, usually seen close to the coast. Here gulls are descendants of crows and terns, sisters to stilts + storks and basal to hummingbirds.

It’s not enough
to get a fully resolved tree or subset thereof when Bootstrap scores are less than 50 for certain nodes. To get them over 50 takes a more robust tree. Presently and provisionally there are strengths and weaknesses in birds as they are here based on generalized LRT reptile traits, rather than bird-specific traits. Working a clade like this, the cladogram tells me what traits to reexamine and why. This is still a limited taxon list, despite it’s overall size. Nevertheless and despite today’s changes, most of the LRT has  grown without the topology shifting very much.

Growing a cladogram
a taxon or two at a time is still superior to the traditional methods: 1) accepting previously published work as true and complete, then adding a new taxon; and 2) building a supertree from several previously published trees and accepting them as true and complete. Experience with the widening gamut of the LRT shows that is not often enough the case.

References
Bourdon E, Kristoffersen AV and Bonde N 2016. A roller-like bird (Coracii) from the Early Eocene of Denmark. Scientific Reports. 6. 34050. doi:10.1038/srep34050
Linneaus C von 1766. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. pp. 1–532. Holmiæ. (Salvius)
Müller S 1836. Reizen en onderzoekingen in den Indischen archipel, gedaan op last der Nederlandsche Indische regering, tusschen de jaren 1828 en 1836, 1857

wiki/Septencoracias
wiki/Fire-tufted_barbet

New insights from the Early Cretaceous bird Changzuiornis

Figure1. Changzuiornis in situ, isolated from matrix, and repositioned to an invivo pose.

Figure1. Changzuiornis in situ, isolated from matrix, and repositioned to an invivo pose, each 5 seconds.

About a year and a half ago,
Huang et al. 2016 brought us a complete and articulated skeleton of a new ornithurine bird, Changzuiornis ahgmi (Fig. 1), from the Early Cretaceous very close to Yanornis. The rostrum is more elongate with a large naris and tiny teeth (Fig. 2).

Please note
the better detail DGS brings to understanding where the bones are in this crushed fossil. The original line drawing (Fig. 2 below) leaves almost everything up to the imagination.

Figure 2. Changzuiornis skull in situ showing what you can do with DGS vs. traditional tracing from the original paper.

Figure 2. Changzuiornis skull in situ showing what you can do with DGS vs. traditional tracing from the original paper.

The maxilla clearly makes up most of the rostrum
in Changzuiornis. And this came as a surprise to Huang et al., who report this is “a characteristic not present in the avian crown clade in which most of the rostrum and nearly the entire facial margin is made up by premaxilla.” (Fig. 3)

Figure 3. From Huang et al. showing in red the extent of the maxilla in their interpretations. This is not long enough according to present interpretations.

Figure 3. From Huang et al. showing in red the extent of the maxilla in their interpretations. This is not long enough according to present interpretations.

It’s actually much worse than they think.
Their interpretation (Fig. 3) of the avian crown clade rostrum is too short, at least for tested taxa like Changzuiornis and Yanornis. Huang et al. do not extend the anterior maxilla far enough anteriorly, ignoring the portion where it overlaps and laminates to the lateral premaxilla (Fig. 2). For comparison, here’s a new interpretation of Struthio, the ostrich with a larger maxilla (Fig. 4) similarly laminated to the lateral premaxilla.

If I’m wrong
I’ll gladly go through a spanking machine (a silly kid’s party game).

If that’s not enough, check out
Yanornis, Cariama, Phoenicopterus, Sagittarius, Llallawavis, Falco and Tyto for a similar anteriorly extended maxillae. All are now repaired from my earlier mistakes as I wrongly followed traditional interpretations.

Figure 3. Struthio skull with a long maxilla.

Figure 3. Struthio skull with a long maxilla.

Otherwise
Changzuiornis is a close sister to Yanornis, with a longer rostrum and some other minor differences apparently a wee bit closer to Gansus, Ichthyornis and Hesperornis. For instance, pedal digits 3 and 4 are similar in length.

Speaking of Hesperornis
It’s difficult to find photographic data on the the rostrum of Hesperornis and Parahesperornis. I failed to do so because authors from Marsh to Gingreich to Martin instead provided line drawings (Fig. 4), which purported to show a tiny maxilla beneath a naris with a premaxilla forming at least half of the ventral margin of the naris. Unfortunately, no sister taxa have such a morphology. Martin 1984 let loose a clue that Parahesperornis had an anteriorly extended maxilla with that line extending anterior to the naris. I provide that option here (Fig. 4 in green) and wish for actual fossil images to work on.

Figure 4. Parahesperornis and Hesperornis skulls with a small traditional maxilla and the a new large one as interpreted here.

Figure 4. Parahesperornis and Hesperornis skulls with a small traditional maxilla and the a new large one as interpreted here.

Ichthyornis and Gansus can’t help us.
Their skulls are too poorly known.

References
Huang J, Wang X, Hu Y-C, Liu J, Peteya JA and Clarke JA 2016. A new ornithurine from the Early Cretaceous of China sheds light on the evolution of early ecological and cranial diversity in birds. PeerJ.com
Martin L 1984. A new Hesperornithid and the relationships of the Mesozoic birds. Transactions of the Kansas Academy of Science 87:141-150.

 

wiki/Parahesperornis

Hornbills, toucans and the Cretaceous

Earlier
the large reptile tree (LRT, 1118 taxa) nested the toucan, Pteroglossus, between the stink bird, Opisthocomus, and the parrot Ara + the giant parrots, Dinornis and Gastornis. That seemed reasonable. They are all frugivores and the nostril is high on parrots and toucans. However, with the addition of two taxa (Figs 2-5), and the reexamination of several others (remember, I’m new to birds) toucans moved from parrots to between crows and ducks (Fig. 4).

Figure 1. Pteroglossus, the toucan shares many traits and nests with Buceros in the LRT.

Figure 1. Pteroglossus, the toucan shares many traits and nests with Buceros in the LRT.

Today
the hornbill, Buceros (Figs. 2,3) is added to the LRT. Traditionally hornbills and toucans do not nest together. All similarities have long been considered convergent. Here, in the LRT, toucans and hornbills do nest together. Very few traits distinguish the two in the LRT.

Figure 2. Buceros skeleton and in vivo image.

Figure 2. Buceros skeleton and in vivo image. Without the horn it does look like a big crow.

So,
toucans are New World hornbills and/or hornbills are Old World toucans. So far… Remember all hypotheses of relationships can be trumped with better and more data.

Pteroglossus aracari (Linneaus 1758) is the extant black-necked aracari, a type of toucan. Toucans are restricted to the New World. Like the parrot, the bill is deep. Unlike the parrot, the nares are dorsal. Like the parrot pedal digit 4 is reversed. Wikipedia reports that toucans are related to woodpeckers. Here toucans are related to hornbills between stink birds and parrots. Like hornbills, toucans nest in tree hollows and are omnivores.

Figure 3. Buceros skull in several views. The smaller drawing shows the nares and antorbital fenestra on a younger bird. Here the premaxilla and maxilla are fused together.

Figure 3. Buceros skull in several views. The smaller drawing shows the nares and antorbital fenestra on a younger bird. Here the premaxilla and maxilla are fused together.

Buceros hydrocorax (Linneaus 1758) is the extant rufous hornbill. Hornbills are restricted to the Old World. Most studies find toucans and hornbills unrelated, similar only by convergence. The present study finds they are sister taxa. Nearly every trait in these two is identical to the other. The separation of toucans and hornbills had to happen by the Albian (Latest Early Cretaceous, 100 mya) based on the distance between the two continents at that time and the fact that these taxa are not long distance flyers.

Figure x. Bird giants in the bird subset of the LRT.

Figure x. Bird giants in the bird subset of the LRT.

The Piciformes question
Wikipedia , representing traditional systematics and taxonomy, nests toucans and barbets with woodpeckers, like Melanerpes, which nests here (Fig. 4) between swifts like Hirundo and dippers with Cinclus, all insect eaters, not frugivores. The LRT recovers a nearly completely different tree topology.

Also added:
Psilopogon pyrolophus (S. Müller 1836; 28 cm in length; SE Asia) is the extant fire-tufted barbet. This frugivore resides at the base of toucans + hornbills and it also uses tree cavities to nest and raise chicks in.

FIgure 5. Psilopogon, is a living barbet from SE Asia.

FIgure 5. Psilopogon, is a living barbet from SE Asia. Other barbets are found in the New World. A pretty little Corvimorph. Note the backward rotated fourth toe, not found in Old World hornbills, but is found in New World toucans.

Of added interest,
hornbills are restricted to the Old World, from Africa to Asia. Toucans are restricted to the New World. Since they shared a last common ancestor similar to both, the two clades must have separated when the continents separated, in the Albian (latest Early Cretaceous, 100 mya; Fig. 6). If true, this supports a growing realization that Neoaves did not radiate after the Cretaceous, but deep within that time period. Jungle taxa do not generally fossilize well. Even so, confirmation will be big news. Smaller barbets are found world wide.

Figure 4. South America and Africa during the Albian, 100 mya. This is when toucans and hornbills must have separated.

Figure 4. South America and Africa during the Albian, 100 mya. This is when toucans and hornbills must have separated.

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.
Müller S 1836. Reizen en onderzoekingen in den Indischen archipel, gedaan op last der Nederlandsche Indische regering, tusschen de jaren 1828 en 1836, 1857

wiki/Black-necked_aracari
wiki/Toucan 
wiki/Rufous_hornbill
wiki/Fire-tufted_barbet

 

Sea gulls: transitional between crows and cranes + hummingbirds + penguins

As we’ve seen over and over
phylogenetic analysis (subset of the LRT in Fig. 3) lets us see behind the curtain of prehistory, revealing evolutionary pathways and relationships that have been largely obscured by phylogenetic miniaturization, convergence and other factors.

Figure 1. Corvus the crow is basal to a long list of taller and shorter birds.

Figure 1. Corvus the crow is basal to a long list of taller and shorter birds. Compare this taxon to the sea gull in figure 2.

Today,
the black-headed sea gull (Chroicocephalus ridibundus; Linneaus 1766; 40cm long; Fig. 2) nests between crows (Fig. 1) and terns and basal to cranes + stilts + hummingbirds and kingfishers + penguins. When you look closely at it (and run the numbers) it really does look like a generalized white crow on its way to creating descendants that would be the most specialized of all birds. 

Figure 1. Chroicocephalus, the black-headed sea gull in vivo and as a skeleton.

Figure 2. Chroicocephalus, the black-headed sea gull (or white crow!) in vivo and as a skeleton.

Sea gulls are so generalized
that there is little about them that creates headlines. But that’s exactly what we (and PAUP) look for when we’re looking for basal and transitional taxa.

Figure 2. The clade of (chiefly) extant birds (Euornithes) with the addition of several taxa including Chroicocephalus, the sea gull (n the pink clade). Chroicocephalus = sea gull. Archilochus = hummingbird. Aptenodytles = penguin.  Grus = crane. 

Figure 3. The clade of (chiefly) extant birds (Euornithes) with the addition of several taxa including Chroicocephalus, the sea gull (n the pink clade). Chroicocephalus = sea gull. Archilochus = hummingbird. Aptenodytles = penguin.  Grus = crane.

The way the LRT is nesting taxa here
(Fig. 3) is creating a different topology from traditional studies. And it suggests a deep, deep radiation extending deep into the Cretaceous, not the Early Tertiary.

References
Linneaus C von 1766. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. pp. 1–532. Holmiæ. (Salvius)

wiki/Black-headed_gull