Guesswork parades as science: the ‘Dawndraco’ debate continues

Kellner 2017 rebutted Martin-Silverstone et al. 2017
who rebutted Kellner 2010 in their taxonomic assessment of a Pteranodon specimen UALVP 24238. Is it congeneric with FHSM VP 339 (GeoternbergiiaP. sternbergi)? Or is the UALVP specimen a distinct genus? Or something else…?

Figure 1. Pteranoodn (Dawndraco) UALVP 24238 in situ, with Martin-Silverstone tracing applied, with mandible moved and missing parts colorized. The putative rostral tip looks more like displaced manus elements.

Figure 1. Pteranoodn (Dawndraco) UALVP 24238 in situ, with Martin-Silverstone tracing applied, with mandible moved and missing parts colorized. The putative rostral tip looks more like displaced manus elements.

Both parties wondered about
gender differences based on pelvis shape. (Both had no clue that the one ‘female’ pelvis they pin their hopes on actually belongs to a giant Nyctosaurus).

Both parties wondered about
maturity at the age of death and used bone fusion as an ontogenetic marker. (Both have no clue that fusion patterns are phylogenetic in pterosaurs because pterosaurs are lepidosaurs and fusion patterns don’t match those of archosaurs, according to Maisano 2002a, b and confirmed by phylogenetic analysis).

Martin-Silverstone et al. dismiss
several observed variations due to postmortem distortion, evidently a favorite excuse of many paleontologists when they have run out of answers that fit their paradigm. (No distortion is found in UALVP 24238).

Name calling, too…
Kellner felt he had to defend being labeled as a ‘splitter’.

Kellner adds one more thought:
“As I have stressed before (Kellner 2010), morphology is crucial for establishing or synonymizing species.” (Very unfortunately both authors do not understand what pterosaurs are: they are fenestrasaur tritosaur lepidosaurs, because they had not performed a phylogenetic analysis in arriving at their conclusions. Only when that happens, THEN establishing and synonymizing species can happen as a result. You just have to read the tree to see who is, or is not, related to who.

Lately everyone in pterosaurs seems to be avoiding
this thing called, “phylogenetic analysis” which, in the large pterosaur tree (LPT, 232 taxa) successfully split and lumped every tested pterosaur specimen, including over a dozen Pteranodon specimens (Fig. 2). It turns out UALVP 24283 (fig. 2, specimen ‘Z’) is not a sister to FHSM VP 339 (Fig. 2, specimen ‘Y’), but both have a common ancestor close to specimen ‘W’ USNM 12167 (Fig. 2, undescribed). Do not accept pterosaur topologies that test only genera and avoid the tiny Solnhofen pterosaurs. You won’t get the big picture and you won’t speak with authority. You’ll floundering in guesswork.

Figure 2. The Tanking-Davis specimen compared to other forms. Specimen w and specimen z appear to be the closest to the Tanking-David specimen. Specimen 'w' = Pteranodon sternbergi? USNM 12167 (undescribed). Specimen 'z' = Pteranodon longiceps? Dawndraco? UALVP 24238. Click to enlarge.

Figure 2.  Click to enlarge. Every reasonably complete Pteranodon skull to scale and in phylogenetic order.

In phylogenetic analysis a big crest
is a derived trait, and yet some small crests and small skulls are derived from big crest ancestors. Only analysis reveals this.

There are no gender differences here.
No two skulls (Fig. 2) are identical except for their crests. And every Pteranodon pelvis is different. The variety here is due to phylogeny, not gender or ontogeny.

Ontogeny is only demonstrated
by the smallest Pteranodon specimens (next to specimen ‘Q’).

Why so much variety in Pteranodon?
Well, there is so much variety in every putative genus in pterosaurs. Add to that, Pteranodon lived for several million years along the long Niobrara Sea that crossed North America from Canada to the Gulf of Mexico… and who knows wherever else. That provides many latitudes for this genus to inhabit and niches to evolve to.

Pterosaur workers,
stop being so lazy! Use specimens for taxa, not a single representative from each genus. That will solve so many taxon exclusion problems, as I can tell you from experience. When you do, let me know what you get. You can safely ignore all previously published topologies that exclude so many taxa. That they are all different teaches us that those all teach us nothing.

If you want my opinion:
Keep all Pteranodon specimens (shown above in Fig. 2) within the genus Pteranodon. Divide them into species. Each one should get it’s own species. Currently ‘Dawndraco‘ nests between several other specimens referred to Pteranodon. That’s how you know ‘Dawndraco‘ really is Pteranodon.

And while you’re at it:
Keep all Rhamphorhynchus specimens (Fig. 3) within the genus Rhamphorhynchus. Divide them into species. Do the same with all Pterodactylus, Dorygnathus, Scaphognathus, etc. genera. Employ more specimens/taxa. Exclude them at your scientific peril.

Figure 3. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O'Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

Figure 3. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O’Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

References
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodon and Systematics of the Pterodactyloidea. [Volumes I & II]. Ph.D. thesis, University of Kansas, University Microfilms International/ProQuest.
Bennett SC 1992. Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology 12: 422–434.
Bennett SC 1994. Taxonomy and systematics of the Late Cretaceous pterosaur Pteranodon (Pterosauria, Pterodactyloidea). Occassional Papers of the Natural History Museum University of Kansas 169: 1–70.
Bennett SC 2001. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Part I. General description of osteology. Palaeontographica, Abteilung A, 260: 1–112. Part II. Functional morphology. Palaeontographica, Abteilung A, 260: 113–153.
Kellner AWA 2010. Comments on the Pteranodontidae (Pterosauria, Pterodactyloidea)
with the description of two new species. Anais da Academia Brasileira de Ciências 82(4): 1063-1084.
Kellner A 2017.  Rebuttal of Martin-Silverstone et al. 2017, ‘Reassessment of Dawndraco kanzai Kellner 2010 and reassignment of the type specimen to Pteranodon sternbergi Harksen, 1966’Vertebrate Anatomy Morphology Palaeontology 3:81–89.
Maisano JA 2002a. The potential utility of postnatal skeletal developmental patterns in squamate phylogenetics. Journal of Vertebrate Paleontology 22:82A.
Maisano JA 2002b. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.
Martin-Silverstone E, Glaser JRN, Acorn JH, Mohr S and Currie PJ 2017. Reassesment of Dawndraco kanzai Kellner, 2010 and reassignment of the type specimen to Pteranodon sternbergi Harksen, 1966.  Vertebrate Anatomy Morphology Palaeontology 3:47-59.
Marsh OC 1876a. Notice of a new sub-order of Pterosauria. American Journal of Science, Series 3, 11:507-509.
Miller HW 1971. A skull of Pteranodon (Longicepia) longiceps Marsh associated with wing and body parts. Kansas Academy of Science, Transactions 74(10):20-33.

http://www.reptileevolution.com/pteranodon-skulls.htm

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Masiakasaurus: a large compsognathid, not a ceratosaur/abelisaur

This new taxon examination began with
a recent paper by Delcourt 2018 on ceratosaur palaeobiology that included Masiakasaurus (famous for its strong procumbent dentition, Fig. 1). When I looked at the restored skull in Delcourt 2018, figure 2, alongside other abelisaur/ceratosaur skulls, I was struck by the thought, first voiced by Ernie on Sesame Street, “One of these things is not like the other.” Other funny examples are here.

Figure 1. Masiakasaurus drawings from Carrano, Loewen and Sertic 2011) with photos from same.

Figure 1. Masiakasaurus drawings from Carrano, Loewen and Sertic 2011) with photos from same.

Delcourt 2018 reported,
“Ceratosaur theropods ruled the Southern Hemisphere until the end of the Late Cretaceous. However, their origin was earlier, during the Early Jurassic, a fact which allowed the group to reach great morphological diversity.” Perhaps there is just a little too much diversity in Delcourt’s taxon list. See below.

Masiakasaurus knopfleri (Sampson, Carrano and Forster 2001; Carrano, Loewen and Sertic 2011) was originally considered a ‘bizarre predatory dinosaur’ related to abelisaurids like Majungasarus. Here, in the large reptile tree (LRT, 1240 taxa) Masiakasaurus is related to Tianyuraptor, which also has procumbent teeth and a long torso. Essentially Masiakasaurus is a larger compsognathid leading to giant tyrannosaurs, not far from larger ornithomimosaurs (Fig. 4).

Figure 2. Tianyuraptor skull in situ and reconstructed.

Figure 2. Tianyuraptor skull in situ and reconstructed.

Other taxa with a descending anterior dentary with teeth
include Tianyuraptor (Fig. 2) and the large Compsognathus (CNJ79, Fig. 3) both of which share a long list of traits with Masiakasaurus. All of these taxa have really long cervical ribs.

Figure 1. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here. There may be an external mandibular fenestra. Hard to tell with the medial view and shifting bones.

Figure 3. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here. There may be an external mandibular fenestra. Hard to tell with the medial view and shifting bones.

Figure 4. Subset to the LRT focusing on Masiakasaurus and kin.

Figure 4. Subset to the LRT focusing on Masiakasaurus and kin.

Taxon exclusion plagues the Delcourt paper. Neither Tianyuraptor nor Compsognathus are mentioned in the text. Nor could I find the taxon Masiakasaurus mentioned with these two.

Inappropriate taxon inclusion. Like Tianyuraptor, Limusaurus also should not have been included as a ceratosaur. The LRT nests Limusaurus with oviraptorids.

When Masiakasaurus was first described
by Sampson et al. 2001, the authors reported, “[Masiakasaurus] is unique in being the only known theropod with a highly procumbent and distinctly heterodont lower dentition. Such a derived dental morphology is otherwise unknown among dinosaurs.” Actually, and this was easy to overlook, the large Compsognathus (Fig. 3) was known since Bidar et al., 1972, but it is more conservative in this feature. Tianyuraptor was reported several years later, in 2010 and the anterior dentary is broken and flipped in situ (Fig. 2). Fukuivenator is known from bits and pieces.

Addendum from Mickey Mortimer:
“Etrigansauria [from the Delcourt paper] is just a junior synonym of Neoceratosauria, which is basically ignored by Delcourt.  The phylogenetic taxonomy in this paper is horrible, ignoring Phylocode Article 11.7, ignoring earlier and better definitions than those of Wilson et al. (2003), redefining Ceratosauroidea as if it were Abelisauroidea, proposing definitions that only work in the topology being used, and citing incorrect definitions for Elaphrosaurinae, Noasaurinae and Furileusauria.  More details on my blog-“

http://theropoddatabase.blogspot.com/2018/06/etrigansauria-unnecessary-demon.html

References
Bidar AL, Demay L and Thomel G 1972b. Compsognathus corallestris,
une nouvelle espèce de dinosaurien théropode du Portlandien de Canjuers (Sud-Est de la France). Annales du Muséum d’Histoire Naturelle de Nice 1:9-40.
Carrano MT, Loewen MA and Sertic JJW 2011. 
New materials of Masiakasaurus knopfleriSampson, Carrano, and Forster, 2001, and implications for the morphology of the Noasauridae (Theropoda: Ceratosauria). Smithsonian Contributions to Paleobiology. 95: 53pp.
Delcourt R 2018. Ceratosaur palaeobiology: new insights on evolution and ecology of the southern rulers. Nature.com/scientificreports 8:9730 | DOI:10.1038/s41598-018-28154-x
Lü J and Brusatte SL 2015. A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution. Scientific Reports 5, 11775; doi: 10.1038/srep11775.
Sampson SD, Carrano MT and Forster CA 2001. A bizarre predatory dinosaur from the Late Cretaceous of Madagascar. Nature. 409 (6819):504–506. doi:10.1038/35054046.
|Zheng X-T; Xu X; You H-L; Zhao, Qi; Dong Z 2010. A short-armed dromaeosaurid from the Jehol Group of China with implications for early dromaeosaurid evolution. Proceedings of the Royal Society B 277 (1679): 211–217.

wiki/Tianyuraptor
wiki/Masiakasaurus
wiki/Fukuivenator

 

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

Chaoyangodens: a transitional monotreme with big canines

Hou and Meng 2014
described a new Jehol eutriconodont mammal, Chaoyangodens lii, (Fig. 1) from the Yixian formation, Early Cretaceous. “The new species has a tooth formula I5-C1-P1-M3/i4-c1-p1-m4, unique among eutriconodonts in having only one premolar in lower and upper jaws, respectively, and a distinctive diastema between the canine and the premolar. Its simple incisors and reduced premolars show a mosaic combination of primitive and derived features.” In other words, this is a transitional taxon, as most are.

Later, Meng and Hou 2016
described ‘the earliest known mammalian stapes’ from the same specimen. “The stapes of Chaoyangodens is reduced in size compared to those of non-mammalian cynodonts and is within the size range of extant mammals.”

Figure 1. Chaoyangodens lii in situ and restored skull in lateral view. This taxon is a monotreme basal to both the echidna and platypus.

Figure 1. Chaoyangodens lii in situ and restored skull in lateral view. At a screen resolution of 72 dpi, this image is twice life size. This mouse-sized taxon is a monotreme basal to both the echidna and platypus.

Figure 2. Subset of the LRT focusing on monotremes and Chaoyangodens.

Figure 2. Subset of the LRT focusing on monotremes and Chaoyangodens.

Here in the large reptile tree (LRT, 1137 taxa, Fig. 2) Chaoyangodens nests between Kuehneotherium and Akidolestes, basal  to the living monotremes, Ornithorhynchus and Tachyglossus.

The top of the Chaoyangodens skull is buried in the matrix. The shape of the skull in lateral view, or at least parts of it, like the position of the orbit (Fig. 1), can be surmised by phylogenetic bracketing.

Based on the nesting of Chaoyangodens
and relatives, like Brasilitherium and Kuehneotherium (Late Triassic), these taxa are all crown mammals, not stem mammals (contra traditional thinking).

Luo, Kielan-Jaworowska and Cifelli (2002)
also nested eutriconodonts within crown mammals and this was confirmed by many later workers. The LRT nests many traditional triconodonts and eutriconodonts elsewhere, both more primitive and more derived.

Recently
we looked at the echidna sister/ancestor, Cifelliodon, here. It also had fewer and bigger teeth in the jaws, though none of those erupted beyond the gum line.

References
Hou S-L and Meng J 2014. A new eutriconodont mammal from the Early Cretaceous Jehol Biota of Liaoning, China. Chinese Science Bulletin 59, 546–553.
Luo Z-X, Kielan-Jaworowska  z and Cifelli RL 2002. In quest for a phylogeny of Mesozoic mammals. Acta Palaeontologica Polonica. 47 (1): 1–78.
Meng J and Hou S-L 2016. Earliest known mammalian stapes from an early Cretaceous eutriconodontan mammal and implications for evolution of mammalian middle ear. Palaeontologica Polonica 67:181–196.

wiki/Eutriconodonta

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 rise of the ruling reptiles (Ezcurra and Butler 2018) fiasco

Taxon exclusion and lack of simple oversight
has once again produced a cladogram (Fig. 1) of untenable relationships. And it got published (Ezcurra and Butler 2018). So many taxa are missing… so many untested assumptions are present… so many ‘by default’ nestings… so many impossible sisters.

Figure 1. Ezcurra and Butler 2018 cladogram. Yellow areas applied here to actual archosauromorph taxa in the LRT.

Figure 1. Ezcurra and Butler 2018 cladogram. Yellow areas applied here to actual archosauromorph taxa in the LRT. White areas are lepidosauromorphs.

This paper basically repeats errors
from earlier works (Nesbitt 2011, Ezcurra 2016). 

The Archosauromorpha is defined as
taxa closer to archosaurs than to lepidosaurs. In the large reptile tree (LRT, 1236 taxa) 
that split follows the basalmost amniote/reptiles, Gephyrostegus and Silvanerpeton. The latter is from the Viséan (Early Carboniferous). A series of amphibian-like reptiles nest at the base of the new Archosauromorpha. This hypothesis of relationships is completely lost on Ezcurra and Butler due to taxon exclusion on a massive scale, following their traditional untested hypotheses of relationships.

When you add more relevant taxa
you will find that the white taxa in figure 1 nest on the lepidosauromorph branch of your greatly expanded tree, while the yellow taxa nest on the archosauromorph branch. And many taxa will fill the gaping morphological gaps present here.

And yes,
many clades, including the Lepidosauromorpha and the Archosauromorpha, recovered from the devastating Permo-Triassic mass extinction event. No argument there.

References
Ezcurra MD 2016.The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriformsPeerJ 4:e1778https://doi.org/10.7717/peerj.1778
Excurra MD and Butler RJ 2018.The rise of the ruling reptiles and ecosystem recovery from the Permo-Triassic mass extinction. Proceedings of the Royal Society B Biological Sciences. DOI: 10.1098/rspb.2018.0361
Nesbitt SJ 2011.
 The early evolution of archosaurs: relationships and the origin of major clades. Bulletin of the American Museum of Natural History 352:1–292 DOI 10.1206/352.1.

Dr. Baron tip-toes around the radiation of dinosaurs

Last year, Dr. Matthew Baron,
not even a year out from his PhD thesis, placed himself in the middle of controversy when Baron, Norman and Barrett 2017 resurrected the clade Ornithoscelida, wrongly uniting plant-eating Ornithischia with meat-eating Theropoda to the exclusion of plant-eating Sauropodomorpha, an invalid (due to taxon exclusion) hypothesis of relationships, we discussed earlier here.

Dr. Baron guessed,Maybe Ornithischia is actually so far removed from the base of the dinosaur tree that no studies, including my own, have been able to properly place them… Its an intriguing thought and one that needs examining properly.” By his own words, Dr. Baron is not yet an authority on the subject. That authority can only come from a wide gamut analysis that minimizes taxon exclusion, like the large reptile tree (LRT, 1236 taxa), which is something that anyone can produce. As noted last year (see citations below), Dr. Baron’s team excluded several relevant taxa.

Figure 2. Look familiar? Here are the pelves of Jeholosaurus and Chilesaurus compared. As discussed earlier, this is how the ornithischian pelvis evolved from that of Eoraptor and basal saurorpodomorpha.

Figure 1. Look familiar? Here are the pelves of Jeholosaurus and Chilesaurus compared. As discussed earlier, this is how the ornithischian pelvis evolved from that of Eoraptor and basal phytodinosauria.

Later Langer et al. 2017 argued against the Baron, Norman and Barrett interpretation. Baron, Norman and Barrett agued back, stating in Baron’s summary, “Langer et al.’s response showed that the alternative arrangement, that preserved the traditional model, was not statistically significantly different to our own hypothesis, and that was with much of our data having been altered, in ways that we perhaps disagree with strongly.”

Baron is correct is noting that Seeley’s original division, uniting sauropodomorphs with theropods based on pelvis orientation “just because a subgroup have gone on to lose a feature that was the ancestral condition for the wider group, it does not mean that we can then say that the other subgroups who have ‘hung on’ to the feature should be grouped together to the exclusion of the experimental group, at least based on that feature’s absence/presence, without other evidence.” Plus it would be one more example of pulling a Larry Martin.

Unfortunately
Dr. Baron pulls out a bad example as his example of the above. He states, “In fact, Cetacea is more closely related to Carnivora than either group are to the Primates.” In counterpoint, in the large reptile tree (LRT, 1236 taxa) there is no clade “Cetacea.” Odontoceti arise from tenrecs and elephant shrews. Mysticeti arise from hippos and desmostylians. Carnivora split apart in the first dichotomy in Eutheria. Thus all other eutherians, including primates, odontocetes and mysticetes have a last common ancestor that is not a member of the Carnivora.

Unfortunately
Dr. Baron bases the above quote on a phylogenetic error when he states, “Like I said before, you need to look at TOTAL EVIDENCE to come to this quite obvious conclusion, which means focusing on more anatomical evidence.” While this may sound reasonable and correct, a focus on anatomical evidence may lead to confusion due to convergence. Bottom line, it is more important to look at the phylogenetic placement of a taxon in order to determine what it is. This has to be done in the context of a wide gamut analysis that minimizes taxon exclusion using at least 150 (sometimes multi-state) characters (the LRT uses 238). Otherwise you’re cherry-picking taxa, something Baron, Norman and Barrett were guilty of by excluding bipedal crocs and several basal dinosaurs from their study (and we know this since the LRT includes them). Baron also cherry-picks traits in part 3 of his argument, pulling a Larry Martin several times in doing so. In a good phylogenetic analysis, like the LRT, you’ll see a gradual accumulation of traits. That means you’ll get a pubis with a transitional phase, a tiny predentary and other traits in gradual accumulation among the outgroups to Ornithischians.

Figure 1. Chilesaurus and kin, including Damonosaurus and basal phytodinosauria.

Figure 2. Chilesaurus and kin, including Damonosaurus and basal phytodinosauria.

Baron promises
“I will eat my shoes!” if Seeley’s dichotomy is correct. That’s an easy promise to make knowing there is a third hypothesis out there: the Theropod/Phytodinosaur dichotomy presented by Bakker (1986) and confirmed by the LRT in 2011.

Pertinent to this discussion
sometimes what a paleontologist does not say about a particular subject can be more important that what a paleontologist does say. I lump taxon exclusion and citation exclusion in the category of ‘what is not said.’

References
Bakker RT 1986. The Dinosaur Heresies.New Theories Unlocking the Mystery of the Dinosuars and Their Extinction. Illustrated. 481 pages. William Morrow & Company.
Baron MG and Barrett PM 2017. A dinosaur missing-link? Chilesaurus and the early evolution of ornithischian dinosaurs. Biology Letters 13, 20170220.
Baron MG, Norman DB and Barrett PM 2017.
A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 543: 501–506;  doi:10.1038/nature21700
Baron MG, Norman DB and Barrett PM 2017. Baron et al. reply. Nature 551: doi:10.1038/nature24012
Langer et al. (8 co-authors) 2017. Untangling the dinosaur family tree. Nature 551: doi:10.1038/nature24011
Novas FE et al. 2015. An enigmatic plant-eating theropod from the Late Jurassic period of Chile. Nature 522(7556), 331.

Relevant blogposts and theses from Dr. Baron:

https://www.academia.edu/36002282/THE_ORIGIN_AND_EARLY_EVOLUTION_OF_THE_DINOSAURIA

What I think about Ornithischia

Thoughts on Ornithoscelida … over one year on … (part 1)

Thoughts on Ornithoscelida … over one year on … (part 2)

Chilesaurus – what is it?

https://pterosaurheresies.wordpress.com/2017/03/23/new-radical-dinosaur-cladogram-baron-norman-and-barrett-2017

https://pterosaurheresies.wordpress.com/2017/03/24/baron-2017-21-unambiguous-theropodornithischian-synapomorphies-dont-pan-out/

https://pterosaurheresies.wordpress.com/2015/06/25/the-dinosaur-heresies-nytimes-book-review-from-1986/

https://pterosaurheresies.wordpress.com/2017/11/03/dinosaur-family-tree-langer-et-al-responds-to-baron-et-al-2017-in-nature/

https://pterosaurheresies.wordpress.com/2017/08/16/you-heard-it-here-first-chilesaurus-is-a-basal-ornithischian-confirmed/