The budgie has a pseudo-jugal!

Figure 1. The number 3 pet in the world (after cats and dogs) is the Budgerigar.

Figure 1. The number 3 pet in the world (after cats and dogs) is the Budgerigar (genus: Melopsittacus).

Everyone loves the budgerigar!
(genus: Melopsittacus undulates), but few people know it has an unusually large/long lacrimal (tan) that curls under the orbit to contact the postfrontal (Fig. 2), as in it’s larger relative, Ara, the macaw. It looks like a typically jugal on other reptiles. The actual very birdy jugal appears beneath it (cyan).

Figure 2. The skull of Melopsittacus in three views. Note the tan lacrimal creating a false-jugal on top of the real jugal (in cyan).

Figure 2. The skull of Melopsittacus in three views. Note the tan lacrimal creating a false-jugal on top of the real jugal (in cyan). There’s a hinge between the nasal and frontal that lifts the premaxilla.

And where is the maxilla?
Hidden inside the premaxilla and overlapping nasal. The last of it is contacting the anterior jugal.

Figure 3. Melopsittacus skeleton. This is the budgie cut to the bone.

Figure 3. Melopsittacus skeleton. This is the budgie cut to the bone.

Melopsittacus undulatus (Linneaus 1758; extant ) is the extant budgerigar, a tiny parrot. Here the nasal wraps around the ventral naris. The lacrimal forms a send jugal below the orbit and contacts the postorbital and squamosal.

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.

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The Zygodactylidae revisited: Smith, DeBee and Clarke 2018

According to Smith, DeBee and Clarke 2018
“Zygodactylidae are an extinct lineage of perching birds characterized by distinct morphologies of the foot and wing elements.”

According to the LRT
(large reptile tree, 1137 taxa) zygodactyly (digits 1 and 4 retroverted) appeared several times by convergence in four unrelated bird clades, including toucansparrots, roadrunners and woodpeckers.

“Although the clade has a complex taxonomic history, current hypotheses place Zygodactylidae as the sister taxon to Passeriformes (i.e., songbirds).”

Earlier we learned that Eozygodactylus (Fig.1) nests with Geococcyx, the roadrunner. Among living zygodactylus birds, only parrots, like Ara, are close to the sparrow, Passer.

“Given the rather sparse fossil record of early passeriforms, the description of zygodactylid taxa is important for inferring potentially ancestral states in the largest radiation of living birds (i.e., the ~6,000 species of extant passeriforms).”

Actually
taxa related to Passer include only Passer at this point in the LRT. Other traditional passeriformes nest elsewhere.

“Despite the exceptional preservation of many specimens and considerable species diversity in Zygodactylidae, the relationships among species have not been previously evaluated in a phylogenetic context.”

Even so, 
the LRT has exposed a problem of taxon exclusion here.

“Herein, we …provide the first hypothesis of the species-level relationships among zygodactylids. The monophyly of Zygodactylidae is supported in these new analyses.”

Figure 2. Eozygodactylus reconstructed from figure 1.

Figure 2. Eozygodactylus reconstructed from figure 1. This represents  only one of four clades with a retroverted digit 4.

As defined by the authors,
“Zygodactylidae Brodkorb, 1971 is an extinct, comparatively species-rich clade of enigmatic birds that possess derived morphological features associated with a perching habitus (Mayr, 2008, 2009, 2015). Zygodactylidae is primarily characterized by a zygodactyl conformation of the pedal phalanges—possessing a retroverted fourth toe and associated accessory trochlea on the distal end of the tarsometatarsus (Olson & Feduccia, 1979).”

The authors chose woodpeckers (Piciformes) as the outgroup.
The unrelated basal barbet/toucan, Cyrilavis, nests at the first dichotomy along with the unrelated Nestor, the parrot. If you are starting to sense yet another case of taxon exclusion, then we are thinking along the same lines.

On the plus side, Botelho et al. 2014 reported
the zygodactyl foot evolved independently in different extant bird taxa.

References
Botelho JF, Smith-Paredes D, Nuñez-Leon D, Soto-Acuña and Vargas AO 2014. The developmental origin of zygodactyl feet and its possible loss in the evolution of Passeriformes.  Proceedings Biological Sciences 281(1788):20140765. doi: 10.1098/rspb.2014.0765.
Smith NA, DeBee AM and Clarke JA 2018.  Systematics and phylogeny of the Zygodactylidae (Aves, Neognathae) with description of a new species from the early Eocene of Wyoming, USA. PeerJ 6:e4950 doi: https://doi.org/10.7717/peerj.4950

The pterosaur tongue bone… and others, too

I did not give the pterosaur tongue much thought
until Li, Zhou and Clarke 2018 discussed it. They report, “Pterosaurs show convergent evolution of traits linked to tongue protrusion and mobility in birds (narrow midline element [achieved through fusion] and elongate, paired and rostrally positioned ceratobranchials).”

Figure 1. Scaphognathus (holotype) with hyoid traced in magenta.

Figure 1. Scaphognathus (holotype) with hyoid traced in magenta.

“We find pterosaurs similarly show lightly-built single pairs of ceratobranchial elements.

“Here, we bring together evidence from preserved hyoid elements from dinosaurs and outgroup archosaurs, including pterosaurs, with enhanced contrast x-ray computed tomography data from extant taxa.” (That means crocs and birds. Pterosaurs are not outgroup archosaurs, but fenestrasaur tritosaur lepidosaurs. Only taxon exclusion and academic suppression prevents this from being widely accepted.)

“The absence of direct and cranially-extensive support from bony elements make crocodilian tongue incapable of significant independent motion. Relative to outgroup lepidosaurs and other tetrapods the bony structure in crocodilians and surveyed basal archosaurs is uniformly simple and small with a single pair of ceratobranchials and no well-mineralized midline element or fusion.” 

“Elongation of hyobranchial elements co-occurs with increased ossification of a midline element (i.e., in paravians) and ceratobranchial fusion on the midline (i.e. pterosaurs). It is also well mineralized in some primarily quadrupedal, herbivorous ornithischians dinosaurs (e.g., ankylosaurids and hadrosauroids.) Within testudines, increase ossification of the midline element is seen in terrestrial taxa with an increase role for intraoral manipulation of food by the tongue.” Quoted verbatim. Ornithischia hyoids from Pinacosaurus are shown in figure 7.

Ludodactylus.

Figure 2. Click to enlarge. Ludodactylus, with rare pterosaur hyoid.

Li, Zhou and Clarke conclude
“In lepidosaurs, which show remarkable diversity in hyoid shape, there remains a primary respiratory function for the hyoid elements. The hyobranchial elements (multiple sets of ceratobranchials) show a primarily dorsoventral movement that is deployed during buccal pumping. The hyoid structure shows strong muscular links to the pectoral girdle that are lost in archosaurs and any tongue protrusion is via attached fleshy extensions rather than bony components. Perhaps not true in fenestrasaurs, which have a bird-like hyoid. See below.

“In Archosauria, the evolution of novel respiratory mechanisms apparently drove a simplification of the tongue that was retained in most taxa. Only with the evolution of flight (birds and pterosaurs) and in select quadrupedal herbivores was tongue structure elaborated.” By convergence, one must assume. Otherwise, what is the common thread?

Li, Zhou and Clarke did not realize
pterosaurs are lepidosaurs, not archosaurs. Anyone can test this by adding more relevant taxa to any relevant cladogram.

Figure 4. Sphenodon hyoids in two views.

Figure 3. Sphenodon hyoids in two views from Jones et al. 2009

Phylogenetic bracketing
using Sphenodon (Schwenk 1986) and Iguana (both with a fleshy tongue and posteriorly branching hyoids) should give tritosaur pterosaurs a fleshy tongue, too… except pterosaurs are highly derived and volant tritosaurs. Only the juvenile Huehuecuetzpalli, otherwise identical to the adult except in size, preserves hyoids. These are only visible posterior to the jaw. “According to their position, the anterior element was identified as the first ceratobranchial and the posterior element as the epihyal. The latter one, however, may be the hyoid cornu.” (Reynoso 1998). Tanystropheus and Macrocnemus have simple slender hyoids that approach one another anteriorly.

Figure 3. Longisquama in situ with hyoids identified.

Figure 4. Longisquama in situ with straight lateral and Y-shaped central hyoids identified.

Overlooked by Li, Zhou and Clarke,
a flightless lepidosaur and pterosaur outgroup taxon, Longisquama (Fig. 4) shares the pterosaur hyoid morphology. Sharovipteryx (Fig. 5) and Kyrgyzsaurus may as well. However in the lateral two taxa the lateral hyoids are so large they appear to have been able to spread laterally and so produce a cobra-like fleshy strake from otherwise loose neck skin and so introduce another aerodynamic membrane. Skull material prevents seeing a central hyoid if present.

Figure 4. Sharovipteryx in situ with hyoids identified. Note the expansive neck skin. Much has been said about the wasp-like insect in the left orbit, but Sharov was an insect collector first and there are many other insects, particularly beetles, all over the matrix.

Figure 5. Sharovipteryx in situ with hyoids identified. Note the expansive neck skin. Much has been said about the wasp-like insect in the left orbit, but Sharov was an insect collector first and there are many other insects, particularly beetles, all over the matrix.

Very few pterosaurs preserve hyoids.
The few that do have bird-like, y-shaped central hyoids (Figs. 1, 2) and sometimes straight lateral hyoids (Fig. 4), as Li, Zhou and Clarke correctly reported.

Yet another bunch of overlooked lepidosauriforms,

  1. Megalancosaurus has a Y-shaped central hyoid, unknown in other drepanosaurs.
  2. Stem chameleon (Early Cretaceous from amber) has a large central element split anteriorly
  3. Chlamydosaurus and kin use the hyoid elements for stretching the dermal skin, whether neck, like the Triassic Sharovipteryx (see above) or throat, as in the anole, Polychrus.
  4. Earliest reptile hyoids I have found: Diplovertebron (Fig. 6, a basal archosauromorph (in the LRT) from the Westphalian, but with its genesis in the Viséan.
Figure 3. Reconstruction of G. watsoni as a distinctly different genus, nesting with Eldeceeon rather than G. bohemicus.

Figure 6. Reconstruction of Diplovertebron (= Gephyrostegus watsoni) showing paired hyoids, the earliest I have seen on a reptile (Westphalian, Late Carboniferous, 300 mya)

Conclusions:
Hyoids vary greatly in size and shape in tetrapods. The basal/typical tetrapod tongue is boneless, fleshy and anchored by hyoids (see Sphenodon (Schwenk 1986), Caiman, Homo or Iguana). A few tongues are modified with an internal Y-shaped element for prey apprehension or reduced mobility, as in Melanerpes and Trioceros. This is found in various lepidosaurs (including pterosaurs) and birds by convergence. Mammals that use their tongues for prey/nectar apprehension do not have hyoids inside the tongue.

Figure 7. A selection of hyoids from Hill et al. 2015 with a focus on the ornithischian, Pinacosaurus.

Figure 7. A selection of hyoids from Hill et al. 2015 with a focus on the ornithischian, Pinacosaurus.

References
Hill RV, D’ Emic MD, Bever GS and Norell MA 2015. A complex hyobranchial apparatus in a Cretaceous dinosaur and the antiquity of avian paraglossalia. Zoological Journal of the Linnean Society 175: 892–909.
Jones et al. 2009. The head and neck muscles associated with feeding in Sphenodon (Reptilia: Lepidosauria: Rhynchocephalia). Palaeontologia Electronica 12(2).
Li Z, Zhou Z and Clarke JA 2018. Convergent evolution of a mobile bony tongue in flghted dinosaurs and pterosaurs. PLoS ONE 13(6):e0198078. https://doi.org/10.1371/journal.
Reynoso V-H 1998. Huehuecuetzpalli mixtecus gen. et sp. nov: a basal squamate (Reptilia) from the Early Cretaceous of Tepexi de Rodríguez, Central México. Philosophical Transactions of the Royal Society, London B 353:477-500.
Schwenk K 1986. Morphology of the tongue in the tuatara, Sphenodon punctatus (Reptilia: Lepidosauria), with comments on function and phylogeny. J Morphol. 1986; 188: 129–156. pone.0198078

The sand grouse (genus: Pterocles) revisited

The spark for this blogpost:
A PH reader considered the nesting of the sandgrouse Pterocles with the horned screamer, Anhima, a mismatch. And it is a mismatch in terms of size, color, feet, legs, etc. The thing is… in the LRT, where only skeletal traits are tested, no other tested taxon nested closer to Anhima than Pterocles.

Figure 1. Anhima adult and chick compared to Pterocles adults

Figure 1. Anhima adult and chick compared to Pterocles adults

Earlier I only had skull data (Fig. 4) for the genus Pterocles (Figs. 1–3) and with that heretically nested Pteroclesthe sand grouse, with Anhima, the screamer (Fig. 2). Sand grouse have traditionally been nested with pigeons and chickens, or between pigeons and chickens (Shufeldt 1901), which are not related to one another in the large reptile tree (LRT, 1236 taxa).

Figure 1. Skeleton of Pterocles, the extant sand grouse. Note the 'calcaneal' tubers and manual digit zero, along with the very tiny clavicle/furcula (green).

Figure 2. Skeleton of Pterocles orientalis arenarius, the extant black-bellied sand grouse. Note the ‘calcaneal’ tubers and manual digit zero, along with the very tiny clavicle/furcula (green). This is a different species than the skull shown in figure 3, hence the different mandible ventral margin shape and other differences.

Pterocles is phylogenetically miniaturized
compared to its larger sister, Anhima, the horned screamer (Fig. 2). Even so, and despite the much larger sternum and much smaller feet, Pterocles retains a digit zero process that also includes a spike in Anhima. Both taxa have a large ‘calcaneal heel’ behind the distal tibia, rare to absent in other birds. In Pterocles pedal digit 1 does not reach the substrate and the furcula is much smaller. Both share more traits with each other than with any other taxa among the 1236 taxa in the LRT.

In this case, at least,
the addition of the post-cranial data changed nothing in the LRT tree topology. It would have been less ‘trouble’ to have Pterocles nest with pigeons, or chickens, but a good scientist reports results, no matter how they differ from tradition.

FIgure 2. The larger Anhima compared to its smaller sister, Pterocles.

FIgure 3. The larger Anhima compared to its smaller sister, Pterocles. Note the digit zero spur on the manus along with the ‘calcaneal tuber’ behind the distal tibia.

Back in 1901
Shufeldt reported, “the sand grouse constitute a small assemblage of forms, related on one hand to the gallinaceous (chicken-like) birds, and on the other to the pigeons.” The two clades are not related to one another in the LRT. And that statement was made before the invention of the airplane, computer and PAUP.

Figure 1. Pterocles, the chestnut-bellied sandgrouse is not related to pigeons, despite convergent appearances, but more closely related to the screamer, Anhima.

Figure 4. Pterocles, the chestnut-bellied sandgrouse is not related to pigeons, despite convergent appearances, but more closely related to the screamer, Anhima.

The Fulica, Anhima, Petrolcles clade
is a basal one, probably extending back to the Early Cretaceous. It is a sister clade to the chicken/sparrow/parrot clade, far from the New World vulture/pigeon clade.

References
Shufeldt RW 1901. On the systematic position of the sand grouse (Pterocles: Syrrhaptes). The American Naturalist 35 (409):11–16.

 

Is a sandgrouse almost a pigeon? Is a sandgrouse almost a grouse?

No. And No.
No matter what you may read, a sandgrouse (genus: Pterocles) does not nest with pigeons in the large reptile tree (LRT, 1235 taxa), but with the screamer, Anhima. And those two do not nest with Tetrao tretix, the black grouse, which nests between chickens and sparrows in the LRT.

Figure 1. Pterocles, the chestnut-bellied sandgrouse is not related to pigeons, despite convergent appearances, but more closely related to the screamer, Anhima.

Figure 1. Pterocles, the chestnut-bellied sandgrouse is not related to pigeons, despite convergent appearances, but more closely related to the screamer, Anhima.

Pterocles exustus (Temminck 1815) is the extant chestnut-bellied sandgrouse. This vegetarian prefers bushy, arid lands.

References
Timminck CJ 1825. Atlas des oiseaux d’Europe, pour servir de complément au Manuel d’ornithologie de M. Temminck. Belin, Paris 1826–42.

wiki/Chauna
wiki/Fulica
wiki/Pterocles

Hello, Robin! Where do you nest?

Short answer:
Turdus migratorius (Linneaus 1758) nests between the crow (Corvus) and the jay (Cyanocritta) in the large reptile tree (LRT, 1232 taxa) based on skeletal traits. 

Figure 1. Turdus migratorius, the American robin, nests between the crow (Corvus) and the blue jay (Cyanocritta).

Figure 1. Turdus migratorius, the American robin, nests between the crow (Corvus) and the blue jay (Cyanocritta).

According to Prum et al. 2015
which tests DNA sequences, Turdus nests with 13 taxa not tested in the LRT along with Corvus, the crow. So there is some agreement here. However, the basal taxon in this subclade within a larger clade, Passeriformes, is Menura, the lyrebird.

By contrast,
in the LRT, Menura nests with cuckoos, apart from crows and jays.

Ironically,
the genus Passer (the sparrow) was not included in the Prum et al. study. In the LRT, Passer nests between chickens and parrots, apart from lyrebirds, robins, crows, and jays. So the Prum et al. study does not tell us if Passer is a passeriform or not. In the LRT, the lyrebird, crow and robin are not related to Passer.

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.

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The curassow (genus: Mitu/Crax) another chicken cousin

Mitu tuberosum aka Crax turberosa (Linneaus 1758, Spix 1825; 85 cm) is the extant razor-billed curassow, a pheasant-like galliform from the Amazon. Only two eggs are laid per year. Precocious young are feathered and mobile after hatching. Omnivorous. Sexes are similar.

Figure 1. Crax tuberosa skeleton and invivo. This basal neognath bird prefers to walk than fly.

Figure 1. The curassow, Mitu tuberosum/Crax tuberosa, skeleton and invivo. This basal neognath bird prefers to walk than fly.

In the large reptile tree (LRT, 1127 taxa) the curassow (genus Mitu or Crax) nests with the Early Cretaceous bird, Eogranivora, and this clade nests with the chicken (Gallus) and the peafowl (Pavo).

Figure 1. Crax tuberosa skull in three views.

Figure 2. The curassow, Crax tuberosa, skull in three views. Note the slender postorbital (yellow) descending from the robust postfrontal (orange).

The helmeted curassow (genus: Pauxi pauxi) has a casque convergent with the cassowary (Casuarius).

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.
von Spix JBR 1825. Avium species novae, quas in itinere per Brasiliam annis MDCCXVII – MDCCCXX […] collegit et descripsit. Franc. Seraph. Hübschmann, Monachii [Munich], 1, [VII], 90 pp., 91 pls.

wiki/Crax
wiki/Mitu
wiki/Razor-billed_curassow