Short one today.
Sometimes those who see things firsthand do not agree on what they see. Today two versions of the Hesperornis palate from the literature (Fig. 1). No photos available to DGS it. Which one is more correct?
Figure 1. Two drawings of the Hesperornis palate. Only a few parts are in agreement. Colors added for clarity.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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
Witton et al. 2017 report in their abstract:
“We found that hatchling pterosaurs were excellent gliders, but with a wing ecomorphology more comparable to powered fliers than obligate gliders.”
Since hatchling pterosaurs were scale models of adults,
and adults were powered fliers, the logic follows. Oddly, Witton wrote a book in which this was not the case when he imagined a pre-hatchling Pterodaustro with a short rostrum and big eyes.
Witton et al. 2017 continue:
“Size differences between pterosaur hatchlings and larger members of their species dictate differences in wing ecomorphology and flight capabilities at different life stages, which might have bearing on pterosaur ontogenetic niching.”
Big science words here say nothing concrete.
Dictate different flight capabilities: no. Dictate different prey items: yes. Note the weasel word: “might have bearing” which acts like a nail in a tire to deflate everything said after it. Try to avoid using weasel words.
References
Witton M, Martin-Silverstone E and Naish D 2017. Glide analysis and bone strength tests indicate powered flight capabilities in hatchling pterosaurs. https://peerj.com/preprints/3216/
Updated October 31, 2020, with the addition of more taxa now nesting Aptornis with the similarly flightless moa, Dinornis, both close to the hoatzin, Opisthocomus. Link here.
If you’ve never heard of the adzebill…
I’m with you. I never heard of it before either. The adzebill (genus: Aptornis, sometimes Apterornis; early Miocene to Holocene; Owen 1844; Figs. 1,2) is a recently extinct large (80 cm in length) flightless bird found only in New Zealand. The question is, what is it?
Figure 1. Aptornis skeleton and parts. This taxon is more derived, more extreme, less pleisomorphic. than the extant kagu.
Figure 2. Aptornis skull. Note the sharp downturned beak, concave premaxilla, lack of prefrontal and the upper temporal fenestra confined by the postorbital and squamosal, very rare in birds.
Figure 3. Dinornis skull for comparison to Aptornis.
A little backstory.
An adze is a tool similar to an ax with an arched blade at right angles to the handle, used for cutting or shaping large pieces of wood. This bird, like the extant kagu, uses its beak as an adze, but the beak and the extant bird are not as derived as in the extinct bird.
Figure 4. Giant Dinornis compared to chicken-sized Opisthocomus to scale and similar in torso length.
Wikipedia reports:
Aptornis has “been placed in the Gruiformes (cranes) but this is not entirely certain.” The report also includes possible relationships to the kagu (Rhynochetos), trumpeters (Psophia), moas (Dinornis, Figs. 3, 4), and the sunbittern (Eurypyga). None of these birds are related to each other in the LRT.
Musser 2017 reports:
“Past morphological studies placed Aptornis as a sister taxon to Rhynochetos jubatus, but recent genomic studies reveal R. jubatus and Eurypyga helias to be sister taxa, and posit that Aptornis falls within Gruoidea.” Musser’s study found strong support for a sister relationship between the kagu, Rhynochetos, and the sunbittern, Eurypgya, but Aptornis nested with the trumpeter, Psophia.
Aptornis defossor
(Owen 1844; 80 cm in length) is the extinct flightless adzebill, which nests with the extinct moa, Dinornis. The rostrum is sharp, short and turns down. The hind limbs are robust. The wings are vestiges.
Figure x. Subset of the LRT focusing on birds. Nahmavis is highlighted in yellow. Color clades include extant taxa.
New Caledonia
is the closest island to New Zealand. These islands which were once contiguous when ocean levels were lower.
References
Musser GM 2017. Resolving the radiation and phenotypic evolution of basal neoaves: beginning construction of a new morphological dataset and a novel sister taxon for Aptornis. Journal of Vertebrate Paleontology abstracts 2017: 167.
Owen R 1844. On Dinornis, an extinct genus of tridactyle struthious birds, with descriptions of portions of the skeleton of five species which formerly existed in New Zealand. (Part I.) Transactions of the Zoological Society of London, 3(3): 235–275,
This is an older post. Many birds have been added and rescored since posting. See the large reptile tree for the latest cladogram.
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. 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 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.
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)
A few days ago, I matched a photo of a blue jay (Cyanocitta) to a skull and discovered the skull tipped back more than one would have thought it would beneath all those feathers.
Along the same lines
a paper by Zusi 1993 showed a series of Galapagos finches (now considered tanagers, evidently) that ignored that tilt according to photo overlays of in vivo specimens (Fig. 1). Zusi preferred to have all the jugals horizontal when they should descend based on in vivo photos.
Figure 1. GIF movie of Galapagos finch skulls, rotated to match photos.
Many birds,
like storks and shoebills, do tilt the skulls down anteriorly, like dogs and ornithocheirids do. Some don’t. It’s best to get it right.
Not sure if this affects scores
in analysis. But if the jugal ‘descends’ or the quadrate ‘leans,’ some scores may change.
References
Zusi RL 1993. Patterns of Diversity in the Avian Skull. Fig. 8.9, pp. 391–437 in Hanken J and Hall BK, The skull, Volume 2: Patterns of structural and systematic diversity. University of Chicago Press, Chicago and London.
Or maybe
kingfishers (genus: Megaceryle, Fig. 1) are just neotonous (juvenile-like) jabirus (genus: Jabiru, Figs. 2, 3). Certainly the jabiru, with its solid beak, ventrally convex jawline and high small naris, are not like other storks.
Figure 1. Megaceryle, the belted kingfisher may be a neotonous jabiru (genus: Jabiru).
Megaceryle alcyon (Linneaus 1758), the extant belted kingfisher, had an enlarged beak on an enlarged skull with a shorter neck. As in parrots, by convergence, the nares have migrated back to the orbit.
Figure 2. Jabiru, a giant, long-legged kingfisher, not a stork.
Jabiru mycteria (Lichtenstein 1819) was a stork-like kingfisher nesting between the stilt/hummingbird clade and the murre/penguin clade (what variety!) Note the high small naris on the ventrally convex rostrum, as in the belted kingfisher.
Figure 3. Skeleton and in vivo views of Jabiru.
If this turns out to be a case of convergence,
and it might… that will come with the addition of more taxa. We’ll see…
References
Lichtenstein H 1819. Archives of Natural History, Volume 35(1):88-99.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
Updated December 24, 2021
with 900 or so more taxa and a revised cladogram.
Today
the large reptile tree (LRT, 1110 taxa) grew by one taxon, the pelican (Pelecanus, Fig. 1). It nested between the hamerkop (Scopus, Figs. 3, 4) and the shoebill (Balaeniceps, Fig. 5, 6).
Figure 2. Scopus umbretta, the extant African hammerkop. The beak is primitively taller than wide and much longer than in Corvus. Note the elevation of the naris and the greater expanse of the maxilla (green).
Scopus umbretta (Brisson 1760, 56 cm tall) is the extant hamerkop, a mid-sized wading bird. It nests with the shoebill and pelican (below) in the LRT. This clade nests between storks and petrels, like Macronectes all derived from Rallus the rail.
Figure 3. Scopus, the hammerkop, in vivo. The beak and legs are longer than in Corvus the crow.
So essentially,
the hamerkop is a long-legged wading crow with a long beak.
Figure 4. Balaeniceps, the shoebill stork. Note the absence of an antorbital fenestra. The maxilla is larger here than on any other bird. Note the majority of the palate is composed of the premaxilla rimmed by the maxilla.
Balaeniceps rex (Gould 1850, up to 140 cm tall) is the extant shoebill stork. It has a broad beak, a flat head and robust cheek bones. Here it nests with the hamerkop and pelican.
Figure 5. Shoebill stork and skeleton. Here the beak was wider and the legs were longer.
So essentially
the shoebill is a longer-legged, broader-billed hamerkop.
Pelecanus onocrotalus (Linneaus 1758) is the extant great white pelican. It has a large skull, longer wings and shorter legs than its relatives, the hamerkop and shoebill.
Figure x. Updated crown bird cladogram from December 2021.
So essentially
the pelican is a short-legged, long rostrum hamerkop.
Key point of today’s blog:
Just think of all the transitional taxa between these terminal extant specimens, now extinct. Pelicans (genus Pelecanus) go back at least 30 million years. Of course, that means the above list of taxa goes back much, much further. Someday we’ll find Late Cretaceous crows and maybe hamerkops, IMHO.
References
Brisson MJ 1760. Ornithologie, ou, Méthode contenant la division des oiseaux en ordres, sections, genres, especes & leurs variétés : a laquelle on a joint une description exacte de chaque espece, avec les citations des auteurs qui en ont traité, les noms quils leur ont donnés, ceux que leur ont donnés les différentes nations, & les noms vulgaires
Gould J 1850. The birds of Asia. Part I. London.
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/Scopus
wiki/Shoebill
wiki/Great_white_pelican
Click to view.
The Pterosaur Heresies 