Darwinopterus: 5 specimens in phylogenetic analysis – part 2

Figure 2. Subset of the large pterosaur tree showing relationships among Darwinopterus and its predecessors among the Wukongopteridae and their predecessors.

Figure 1. Subset of the large pterosaur tree showing relationships among Darwinopterus and its predecessors among the Wukongopteridae and their predecessors.

Yesterday we looked at the phylogenetic ancestors (Fig. 1) of Darwinopterus. Today we’ll take a closer look at the five specimens assigned to this genus.

Lü et al. (2011) noted the alveoli have raised margins, the nasoantorbital fenestra were confluent [not true, if you look closely], inclined quadrate [plesiomorphic], elongate cervical vertebrae with low neural spine and reduced or absent cervical ribs [plesiomorphic], long tail of more than 20 caudals partially enclosed by filiform extensions of the pre- and post-zygopophyses [plesiomorphic] short metacarpus less than 60 percent length of humerus [plesiomorphic] fifth toe with two elongate phalanges [plesiomorphic] and curved second pedal phalanx with the angle of 130 degrees [plesiomorphic].

In the current analysis
the following traits distinguish Darwinopterus from outgroup taxa: Some are equivocal, subject to a change of score by virtue of taphonomic changes and exposure. Only the first two dorsal ribs are robust, not the first three. The humerus shape is straighter. The deltopectoral crest is wider than deep. Manual 1.1 is shorter relative to m2.1. Manual digit 3 is not longer than mt4. The prepubis is putter-shaped. So, really not much. Only 5 steps are added when the outgroup taxa are moved inside the clade.

The most basal taxon
is the female, ZMNH M8802 (Fig. 2) which is crestless, like its ancestors. The mandible tip is bent down.

Figure 2. Darwinoperus ZMNH8802 specimen, the female and most basal member of this genus.

Figure 2. Darwinoperus ZMNH8802 specimen, the female and most basal member of this genus.

On a side note:
The original ischium (Fig. 2a) was misidentified. It is hard to see on top of the right femur (on the left below as seen in ventral view). What was originally identified as a deep left ischium by Lü et al. is instead a second prepubis, identical to the correctly identified prepubis on the opposite side (Fig. 2a, b)

Figure 2a. Original identification by Lü et al. 2011a) of puboischium in Darwinopterus.

Figure 2a. Original identification by Lü et al. 2011a) of puboischium in Darwinopterus.

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Figure 2b. Darwinopterus female pelvis (ZMNH 8802) with pelvic bones correctly identified. the ischium is best seen on the left in indigo. The prepubes are red.

Figure 2b. Darwinopterus female pelvis (ZMNH 8802) with pelvic bones correctly identified. the ischium is best seen on the left in indigo. The prepubes are red. The egg has been flattened and deflated, like a balloon. The paired ischia are still deep enough to pass the egg in vivo.

The other four specimens have crests. The other four specimens have a shorter prepubis relative to the pelvis. Again, not much separates them.

The next clade
has two similar members, D. linglongtaensis (Fig. 3) and the YH2000 specimen (Fig. 4). Both are relatively gracile. The orbit is more upright. The mandible is gracile and slightly bent up distally. Some dentary teeth are taller than the mandible. The sacrum is mostly fused. The torso is longer relative to the humerus, separating the elbow from the ilium. The humerus is subequal to the femur. The ulna is longer relative to the humerus. Manual 2.1 and m3.1 are subequal. Manual 3.3 ≥ m3.1 + m3.2. When folded manual 4.1 extends only to the distal ulna, not the half point. Metatarsals 1 and 2 are the longest. Pedal 4.4 is shorter than p4.1.

Figure 3. Darwinopterus YH2000 specimen.

Figure 3. Darwinopterus YH2000 specimen. It has a shorter ilium and a gracile build.

Minor differences, getting into the range of individual variation, separate the YH2000 and IVPP V 16049 specimens. The latter is more robust with a longer ilium and a shorter p5.1.

Figure 4. Darwinopterus linglongtaensis.

Figure 4. Darwinopterus linglongtaensis, IVPP V 16049. This is a robust specimen.

The third clade
has larger members, the Darwinopterus modulars holotype (ZMNH 8782, Fig. 5) and D. robustodens (41HIII-0309A, Fig. 6). The postorbital bar is lower and more robust. The coracoid is less than half the length of the humerus. The humerus is longer relative to the torso. The pubis depth is not shorter than the ischium.

Figure 5. Darwinopterus ZMNH 8782. A taller specimen with a longer neck and larger skull.

Figure 5. Darwinopterus modularis (holotype) ZMNH 8782. A taller specimen with a longer neck and larger skull.

Again, minor differences separate these two, including the length of the neck, distribution of the teeth, a more robust tail in the holotype, and the pelvis shape.

Figure 6. Darwinopterus robustodens at the Henan Geological Museum (41HIII-0309A). The teeth tips are described (Lü et al. 2011) as sharper and are swollen between the crown and root. There are nine tooth pairs in the upper and eleven in the lower jaws, which are smaller than in D. modularis.

Figure 6. Darwinopterus robustodens at the Henan Geological Museum (41HIII-0309A). The teeth tips are described (Lü et al. 2011) as sharper and are swollen between the crown and root. There are nine tooth pairs in the upper and eleven in the lower jaws, which are smaller than in D. modulars. Tomorrow we’ll take a closer look at the naris.

If we concentrate only the feet
We find a gradual evolution and a resulting variety in the pes of the included taxa (Fig. 7). Note the variation in p5.1 vs. mt4, the longest toe from the heel, the variety in metatarsal lengths and the relative lengths of metatarsus to digits.

Figure 6. Darwinopterus feet. If the gracile forms were female, would they have phylogenetically different feet? Or is it more parsimonious to consider the morphologically different forms a clade?

Figure 7. Darwinopterus feet. If the gracile forms were female, would they have phylogenetically different feet? Or is it more parsimonious to consider the morphologically different forms a clade?

The wukongopterids were an interesting clade, evolving some pterodactyloid-grade traits, but not others. The multiple origin of the pterodactyloid-grade is a subject we handled earlier here. If you want to see all the wukongopterids together to scale, click here

References
Lü J, Unwin DM, Jin X, Liu Y and Ji Q 2009. Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceedings of the Royal Society London B  (DOI 10.1098/rspb.2009.1603.)
Lü J, Unwin DM, Deeming DC, Jin X, Liu Y and Ji Q 2011a. An egg-adult association, gender, and reproduction in pterosaurs. Science, 331(6015): 321-324. doi:10.1126/science.1197323
Lü J, Xu L, Chang H and Zhang X 2011b. A new darwinopterid pterosaur from the Middle Jurassic of Western Liaoning, northeastern China and its ecological implicaitions. Acta Geologica Sinica 85: 507-514.
Lü J-C and Fucha X-H 2010. A new pterosaur (Pterosauria) from Middle Jurassic Tiaojishan Formation of western Liaoning, China. Global Geology 13 (3/4): 113–118. doi:10.3969/j.issn.1673-9736.2010.03/04.01.
Martill DM and Etches E 2012. A new monofenestratan pterosaur from the Kimmeridge Clay Formation (Upper Jurassic, Kimmeridgian) of Dorset, England. Acta Palaeontologica Polonica. in press. doi:10.4202/app.2011.0071.
Wang X, Kellner AWA, Jiang S-X, Cheng X, Meng Xi & Rodrigues T 2010. New long-tailed pterosaurs (Wukongopteridae) from western Liaoning, China. Anais da Academia Brasileira de Ciências 82 (4): 1045–1062.
Wang X-L, Kellner AWA, Jiang S-S, Cheng X, Meng X and Rodriques T 2014. New long-tailed pterosaurs (Wukongopteridae) from western Liaoning, China. Anais da Academia Brasileira de Ciências (2010) 82(4): 1045-1062.
Zhou C-F and Schoch RR 2011. New material of the non-pterodactyloid pterosaur Changchengopterus pani LÜ, 2009 from the Late Jurassic Tiaojishan Formation of western Liaoning. N. Jb. Geol. Paläont. Abh. 260/3, 265–275 published online March 2011.

wiki/Kunpengopterus
wiki/Darwinopterus

Darwinopterus: 5 specimens in phylogenetic analysis – part 1

Earlier we looked at Darwinopterus, of which several specimens (Figs. 1,2) are now known. When the female with the associated egg was found (Lü et al. 2011a) they proposed that some of the differences (pelvis shape, rostral crest, size) could be attributed to gender.

We learned earlier that this would be a unique situation among pterosaurs as all other such candidates for this difference do not indicate gender, but phylogeny when placed under analysis (small crests are derived from no crests and small crests give rise to large crests, for instance). What Lü et al. considered a deep ischium in the female was found to be a deep prepubis here.

Like Pteranodon, Rhamphorhynchus, Pterodactylus, Germanodactylus and other genera, I added the five specimens attributed to Darwinopterus (Fig. 1) to the large pterosaur tree to see how they might be related to one another in a first ever phylogenetic analysis of this genus (Fig. 2).

Figure 1. Click to enlarge. The five specimens of Darwinopterus to scale and in phylogenetic order preceded by six more primitive taxa. The ZMNH 8802 specimen is a female associated with an egg. The others genders shown are guesses by Lü et al. 2011a. Note the skull did not elongate, it actually shrank in the vertical dimension, probably reducing its weight. The female is crestless because it is the most primitive of the five known Darwinopterus specimens. The odds that the remaining four specimens are all males is relatively small.

Figure 1. Click to enlarge. The five specimens of Darwinopterus to scale and in phylogenetic order preceded by six more primitive taxa. The ZMNH 8802 specimen is a female associated with an egg. The others genders shown are guesses by Lü et al. 2011a. Note the skull did not elongate, it actually shrank in the vertical dimension, probably reducing its weight. The female is crestless because it is the most primitive of the five known Darwinopterus specimens. The odds that the remaining four specimens are all males is relatively small. The odd throat sac of Pterorhynchus may represent a normal throat ripped away from its base.

Figure 2. Subset of the large pterosaur tree showing relationships among Darwinopterus and its predecessors among the Wukongopteridae and their predecessors.

Figure 2. Subset of the large pterosaur tree showing relationships among Darwinopterus and its predecessors among the Wukongopteridae and their predecessors.

To give some perspective
Jianchangnathus, at the base of this subset of the large pterosaur tree, also nested between basal Dorygnathus and Scaphognathus. No taxa succeed Darwinopterus. It was a sterile lineage, not a transitional taxon.

Note the very small naris and relatively large skull on Jianchangnathus. More derived taxa, including Darwinopterus, had a skull that was just as long, just not as tall, thereby reducing its weight. So this clade did not have a longer skull than sister taxa.

All more derived taxa, including Darwinopterus, also had a reduced to absent naris. So this is the genesis of that trait.

The long neck of wukongopterids also had its genesis in more basal taxa, like the PMOL specimen attributed to Changchengopterus by Zhou and Shoch 2011.

Earlier we noted the relationship of Pterorhynchus to the wukongopterids. And recently we noted that the new specimen referred to Changchengopterus (Zhou and Schoch 2011) actually nests at the base of the Wukonopteridae, far from the the holotype Changchengopterus, which is half the size.

Kunpengopterus now has a sister taxon in Archaeoistiodactylus (Lü and Fucha 2010) which Martill and Etches (2012) correctly referred to this clade.

Tomorrow we’ll look at the five specimens of Darwinopterus a little more closely.

References
Lü J, Unwin DM, Jin X, Liu Y and Ji Q 2009. Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceedings of the Royal Society London B  (DOI 10.1098/rspb.2009.1603.)
Lü J, Unwin DM, Deeming DC, Jin X, Liu Y and Ji Q 2011a. An egg-adult association, gender, and reproduction in pterosaurs. Science, 331(6015): 321-324. doi:10.1126/science.1197323
Lü J, Xu L, Chang H and Zhang X 2011b. A new darwinopterid pterosaur from the Middle Jurassic of Western Liaoning, northeastern China and its ecological implicaitions. Acta Geologica Sinica 85: 507-514.
Lü J-C and Fucha X-H 2010. A new pterosaur (Pterosauria) from Middle Jurassic Tiaojishan Formation of western Liaoning, China. Global Geology 13 (3/4): 113–118. doi:10.3969/j.issn.1673-9736.2010.03/04.01.
Martill DM and Etches E 2012. A new monofenestratan pterosaur from the Kimmeridge Clay Formation (Upper Jurassic, Kimmeridgian) of Dorset, England. Acta Palaeontologica Polonica. in press. doi:10.4202/app.2011.0071.
Wang X, Kellner AWA, Jiang S-X, Cheng X, Meng Xi & Rodrigues T 2010. New long-tailed pterosaurs (Wukongopteridae) from western Liaoning, China. Anais da Academia Brasileira de Ciências 82 (4): 1045–1062.
Wang X-L, Kellner AWA, Jiang S-S, Cheng X, Meng X and Rodriques T 2014. New long-tailed pterosaurs (Wukongopteridae) from western Liaoning, China. Anais da Academia Brasileira de Ciências (2010) 82(4): 1045-1062.
Zhou C-F and Schoch RR 2011. New material of the non-pterodactyloid pterosaur Changchengopterus pani LÜ, 2009 from the Late Jurassic Tiaojishan Formation of western Liaoning. N. Jb. Geol. Paläont. Abh. 260/3, 265–275 published online March 2011.

wiki/Kunpengopterus
wiki/Darwinopterus

MorphoBank.org has three new matrices

Okay,
for those interested in getting my matrices from MorphoBank.org rather than from me, the large reptile tree, basal therapsid tree and large pterosaur tree are now available online at Morphobank.org.

Projects 1071, 1072, 1073 

This represents a change from the original project 753 in which all three matrices were in one project.

In total the taxon list is now up to 623 (with a few overlaps due to the three matrices.)

Azendohsaurus postcrania – svp abstracts 2013

From the abstract:
Nesbitt et al. 2013 wrote, “During the Triassic, a number of highly disparate archosauromorphs populated both terrestrial (e.g., Trilophosaurus, rhynchosaurs) and marine ecosystems (e.g., tanystropheids) across Pangea. Unfortunately, the unique and sometimes utterly bizarre body plans of these reptiles (e.g., specialized feeding adaptations) create a major challenge in understanding early archosauromorph relationships and patterns of diversification, as teasing apart homology from homoplasy has been difficult with the current sample of taxa.

“Here we present the postcranial anatomy of Azendohsaurus madagaskarensis, an early archosauromorph from the Middle-Late Triassic of Madagascar. Azendohsaurus madagaskarensis comes from a monotypic bone bed containing an ontogenetically variable sample, with preservation ranging from whole, disarticulated bones, to articulated partial skeletons. From this bonebed, the entire anatomy of the taxon is represented. Azendohsaurus madagaskarensis possessed an elongated neck, short tail, and stocky limbs. The manus and pes have unexpectedly short digits, terminating in large, recurved ungual phalanges. Together with the skull, knowledge of the postcranial skeleton elevates A. madagaskarensis to another highly apomorphic and bizarre Triassic archosauromorph.

“Even so, recovery, description and analysis of the full anatomy of A. madagaskarensis provides clues to understanding the relationships of this species and other problematic and anatomically specialized taxa, including the North American Late Triassic archosauromorphs Trilophosaurus and Teraterpeton. For example, A. madagaskarensis, Trilophosaurus, and Teraterpeton share a dorsally hooked quadrate and enlarged, trenchant unguals, whereas Trilophosaurus and Teraterpeton alone share a number of other character states (e.g., restricted scapular blade, premaxillary beak). We tested these observations in a newly constructed phylogenetic analysis centered on Triassic archosauromorphs and archosauriforms. We find that A. madagaskarensis, Trilophosaurus, Spinosuchus, and Teraterpeton form a clade within Archosauromorpha, but the relationships of this clade to other groups of Triassic archosauromorphs (e.g., archosauriforms, rhynchosaurs, tanystropheids) remains poorly supported. The newly recognized clade containing A. madagaskarensis, Trilophosaurus, and Teraterpeton demonstrates high disparity of feeding adaptations even within a closely related group of basal archosauromorphs.”

The rhynchosaur Hyperodapedon, the protorhynchosaur, Mesosuchus and the two Trlophosaurs, Trilophosaurus and Azendohsaurus are here.

Figure 1. Click to enlarge. On the left, the rhynchosaur Hyperodapedon, the protorhynchosaur, Mesosuchus and the two Trlophosaurs, Trilophosaurus and Azendohsaurus. On the right, basal archosauriforms and Azendohsaurs tucked in the bottom along with a tree segment.

First of all,
its great to hear the postcrania of Azendohsaurus is finally on the table, soon to be published, I presume. The skull nests it as a sister to Trilophosaurus, so the long neck is no surprise and Sapheosaurus. The short tail, short digits and stocky limbs of Azendohsaurus are found phylogenetically nearby in the rhynchosaur Hyperodapedon and the proto-rhynchosaur, Mesosuchus. So, again, no surprise there. This clade has surprising diversity.

Second of all,
Nesbitt et al. 2013 think these taxa are bizarre only because they are under the presumption that they are all archosauromorphs. They are not, as documented by the large reptile tree. It’s no surprise then that Nesbitt et al. report, “relationships remains poorly supported.” Evidently Nesbitt et al. 2013 don’t have a large enough gamut in their reptile tree to recovers their featured taxa as lepidosauromorphs, closer to lepidosaurs than to archosaurs.

When Nesbitt et al. finally do figure out how to nest those taxa, they’ll also find out that their new sister taxa provide a gradual accumulation of traits that lead to all their oddball traits. It’s the same problem Nesbitt 2011 made nesting pterosaurs with archosaurs. In reality, when you don’t exclude the better candidates, tritosaur lepidosaurs provide the gradual accumulation of pterosaurian traits.

Nesbitt 2011 already made the big mistake of nesting Mesosuchus as a basal archosauromorph when it is way closer to sphenodontids. Youngina would have been a better choice as a basal archosauromorph. It’s way more plesiomorphic with regards to proterosuchids, erythrosuchids and choristorderes. 

The exception

Figure 2. Teraterpeton, a former enigma that nests here between  Chanaresuchus and Tropidosuchus.

Figure 2. Teraterpeton, a former enigma that nests in the large reptile tree between Chanaresuchus and Tropidosuchus. While oddballs sometimes nest together, this taxon has little in common with Trilophosaurus.

Teraterpeton is the exception, a pararchosauriform archosaurormorph nesting between Chanaresuchus and Tropidosuchus in the large reptile tree. Earlier we looked at Teraterpeton here. Nesbitt et al. found that Teraterpeton, Trilophosaurus and Azendohsaurus shared a dorsally hooked quadrate and enlarged trenchant unguals. Unfortunately, more that 30 steps are added when Teraterpeton shifts to nest with the other two and the unguals are not really that big in Teraterpeton. They’re actually bigger in the sister taxon, Chanaresuchus. The quadrate often hooks in herbivores. That they have in common.

Gosh,
I hope the Nesbitt team goes to a larger gamut tree and tests their taxa against other candidates before they publish another problem-filled paper like Nesbitt (2011) with strange bedfellows (sisters that don’t share very many traits) all over the place. The nestings of these featured taxa in the large reptile tree are strongly supported.

References
Nesbitt, S, Flynn J, Ranivohrimanina L, Pritchard A and Wyss A 2013.
Relationships among the bizarre: the anatomy of Azendohsaurus madagaskarensis and its implications for resolving early archosauromroph phylogeny. Journal of Vertebrate Paleontology abstracts 2013.

The Early Tetrapod Supertrees of Ruta, Jefferies and Coates 2003

A decade ago, Ruta et al. (2003) produced two distinct phylogenetic supertrees of early tetrapods by combining 50 trees produced by prior workers. That’s 225 taxa in total, an impressive number! The second analysis excluded source trees that had been superceded by more comprehensive studies. Only a very few of the taxa on both trees are found in the large reptile tree (colorized in Figs. 1, 2).

Figure 1. Click to enlarge. Colors added represent taxa listed on the large reptile tree.

Figure 1. Click to enlarge. Colors added represent taxa listed on the large reptile tree.

Since the large reptile tree includes several pre-amniotes listed here (Figs. 1, 2), I thought it would be interesting to compare and contrast these two trees as Ruta et al. (2003) did, “Outstanding areas of disagreement include the branching sequence of lepospondyls and the content of the amniote crown group, in particular the placement of diadectomorphs as stem diapsids.”

Figure 2. The second super tree created by Ruta et al. 2003. Note the several shifts described in the text.

Figure 2. The second super tree created by Ruta et al. 2003. Note the several shifts described in the text.

Figure 1. Microsaurs and other basal non-amniote tetrapods from the large reptile tree.

Figure 1. Microsaurs and other basal non-amniote tetrapods from the large reptile tree.

Ruta et al. (2003) warn in their abstract: “Supertrees are unsurpassed in their ability to summarize relationship patterns from multiple independent topologies. However, we urge caution in using them as a replacement for character-based cladograms and for inferring macroevolutionary patterns.”

They also report, “supertrees can, in certain circumstances, produce spurious groups (i.e. taxon arrangements that are not found in any of the contributory trees.”

[Hone and Benton (2009) know this only too well!!]

In analysis one,
Ruta et al. report, “Authors hypothesize a close relationship between some or all of the lissamphibians and various lepospondyl groups (figure 1). However, analysis I places lissamphibians as a sister group to a clade of lysorophids and microbrachomorph microsaurs. The amniote crown group and total group are coextensive: no amniote stem was found.”

In analysis two, 
Ruta et al. report, “[The] tree shows a deep split within early tetrapods between stem amniotes and stem lissamphibians analysis II includes a stem amniote branch. Anthracosaurs and seymouriamorphs are successive sister groups to a clade of crown amniotes plus diadectomorphs. This larger group is paired with Solenodonsaurus plus lepospondyls. Caerorhachis is placed at the base of the amniote stem (cf. Ruta et al. 2001, 2003). Finally, Casineria and Westlothiana are successive sister taxa to the crown amniotes. Temnospondyls now appear as stem lissamphibians.”

Spurious results,
Ruta et al. report, “Diadectomorphs are polyphyletic in most MPTs, Diadectes and Limnoscelis being nested within the amniote crown, next to stem diapsids. Solenodonsaurus also appears as a crown amniote, as a sister taxon to the diadectomorph, Tseajaia.”

No, that’s good!
The large reptile tree also recovered Solenodonsaurus, TseajaiaDiadectes and Limnoscelis as amniotes. So what’s the problem!

In their summary, Ruta et al. (2003) remind us,
“Supertree methods are the only practical means of generating summaries of primary results.”

Interesting then,
that when Hone and Benton (2009) following Hone and Benton (2007) in their 2-part supertree analysis decided to drop all reference to Peters (2000) and give false credit for the “prolacertiform” hypothesis to Bennett (1996), they must have discovered that inclusion of the primary results from Peters (2000) would give them the same results as Peters (2000). This they were not keen on doing, considering their subsequent deviations. Their mission, as stated in 2007, was to compare the results of Peters (2000) to Bennett (1996). By dropping the former in their 2009 paper (with published analysis), the latter came out victorious, but only by default and not very clearly.

Later Bennett (2013) noted that Hone and Benton (2009) entered typos into their matrix for Peters (2000) then complained they did not get the same results, among many other problems listed here.

Back to Ruta et al. 
Interesting that the Ruta et al. supertree kept Gephyrostegus apart from basal amniotes, perhaps due to the absence of Cephalerpeton, Brouffia and other basal amniotes. Moreover, Gephyrostegus, Silvanerpeton and Proterogyrinus nested in opposite order with the latter nesting as more derived. We found that opposite order also occurring with the Mortimer dinosaur tree here.

Good fodder for good conversation.
Ultimately we’ll all be of one accord.

Bottom line:
You have to appreciate the efforts of Ruta  et al. 2003 because more taxa in large gamut analyses generally aid in understanding relationships… so long as you don’t “drop the ball” by deleting key taxa (as in Hone and Benton (2007, 2009).

References
Ruta M, Jefferey JE and Coates MI 2003. A supertree of early tetrapods. Proceedings of the Royal Society, London B (2003) 270, 2507–2516.
Hone DWE and Benton MJ 2007. An evaluation of the phylogenetic relationships of the pterosaurs to the archosauromorph reptiles. Journal of Systematic Palaeontology 5:465–469.
Hone DWE and Benton MJ 2009. Contrasting supertree and total evidence methods: the origin of the pterosaurs. Zitteliana B28:35–60.

If basal fenestrasaurs did not exist, where else would pterosaurs nest?

The utility of having a very large gamut reptile family tree with full resolution is the complete freedom to make deletions to test “what if” scenarios. Today we’ll take away the closest known ancestors of pterosaurs in a stepwise fashion to see when and if pterosaurs break from their natural nesting and go join an unrelated clade by default. It will be as if these disappearing genera were never discovered or were never born (shades of Frank Capra’s “It’s A Wonderful Life”)!

Figure 1. Click to enlarge. Kyrgyzsaurus to scale alongside other basal fenestrasaurs, Cosesaurus, Sharovipteryx and Longisquama. Kyrgyzsaurus likely was a biped with long legs. We know from the shape of its coracoids that it was a flapper.

Figure 1. Click to enlarge. Kyrgyzsaurus to scale alongside other basal fenestrasaurs, Cosesaurus, Sharovipteryx and Longisquama. Kyrgyzsaurus likely was a biped with long legs. We know from the shape of its coracoids that it was a flapper.

Deletion of the Fenestrasaurs - 
If Cosesaurus, Kyrgyzsaurus, Sharovipteryx and Longisquama (Fig.1) were unknown the basal pterosaur MPUM6009 would nest between Macrocnemus and Jesairosaurus (Fig. 2) at the base of the drepanosauromorpha) leaving the large reptile tree topology unchanged.

Another Deletion -
If Macrocnemus, Jesairosaurus (Fig. 2) and the drepanosauromorpha were unknown, the pterosaur would nest with Huehuecuetzpalli (Fig. 2).

One Addition, Then Another
If only Jesairosaurus is added back in, the pterosaur would nest with it. If only Macrocnemus is added back in, the pterosaur would nest with it.

And a Final Deletion -
If Huehuecuetzpalli were unknown, the pterosaur MPUM6009 would finally “jump ship” and nest by default between Proterosuchus and Doswellia. As it turns out, the outgroup taxon to Huehuecuetzpalli, the basal lepidosaurs Tijubina and Lacertulus (Fig. 2) are not as attractive to MPUM  6009 as those archosauriforms.

So this is the breaking point. 
At this point pterosaurs move to archosauriforms, where everyone else thinks they should go, but just in the absence of good data from the above named taxa. Strangely pterosaurs don’t bounce to Scleromochlus, which is sitting there waiting…

Why Proterosuchus?
Like pterosaurs, Proterosuchus had an antorbiteal fenestra without the fossa that appeared in all more derived archosauriforms. Proterosuchus also had an asymmetric pes with a longer digit 4 than digit 3, as in basal pterosaurs. Scleromochlus doesn’t offer those traits, which is why in Bennett (1996) pterosaurs nested close to Proterosuchus after the deletion of hind limb traits. Hone and Benton (2009) nested Cosesaurus next to Proterosuchus (Fig. 3) perhaps for the same reason. Not sure about that mixed up study.

Fig. 6. Hone and Benton recovered Cosesaurus as a sister to Proterosuchus, which, on the face of it, appears unlikely.

Fig. 3. Hone and Benton recovered Cosesaurus as a sister to Proterosuchus, which, on the face of it, appears unlikely.

Recent Pterosaur Studies in the Archosauria
So now we turn to recent studies (Nesbitt 2011) in which pterosaurs nested by default between phytosaurs and Lagerpeton and Marasuchus. And Brusatte et al. (2010), in which pterosaurs nested with Scleromochlus and that clade was derived from Proterochampa and Euparkeria. None of these recent studies included Huehuecuetzpalli, Jesairosaurus, Macrocnemus and the fenestrasaurs. So it was not possible for pterosaurs to nest with their more natural, more parsimonious sisters.

Pterosaurs did not nest with Proterosuchus in Nesbitt (2011) and Bursatte et al. (2010) because the list of tested characters differed. More emphasis was placed in these two studies on archosaurian traits than generalized reptile traits, as in the large reptile tree.

You might remember
that Witton (2013) dismissed the idea that pterosaurs could be squamates and the present tests agree with this supposition. When give the opportunity, pterosaurs do nest closer to Proterosuchus than to squamates whenever the above taxa are deleted. Unfortunately Witton (2013) omitted the fact that the Tritosauria (now containing several former prolacertiformes) nest outside the Squamata. By putting on those blinders, or not giving you all the facts, he lost his chance to confirm the nesting of pterosaurs with fenestrasaurs. Huehuecuetzpalli is the key taxon uniting the plain old basal tritosaur lizards with the wildly outrageous taxa that followed.

You may be thinking I forgot some taxa
Yes, the clade including AmotosaurusLangobardisaurus (Fig. 2), Tanytrachelos and two Tanystropheus do indeed nest between drepanosauromorphs and fenestrasaurs. At present they appear only in the large pterosaur tree, not the large reptile tree. No wonder Tanystropheus was first considered a pterosaur! Absent those other sisters (listed above), that bizarre giant would have been the closest known taxon to pterosaurs, and probably was for several decades in the 19th century.

Squamates, tritosaurs and fenestrasaurs in the phylogenetic lineage preceding the origin of the Pterosauria.

Click to enlarge. Squamates, tritosaurs and fenestrasaurs in the phylogenetic lineage preceding the origin of the Pterosauria.

As an aside
Earlier we looked at the deletion of all Lepidosauromorpha (one entire branch of the diphyletic Reptilia) – except the turtle Proganochelys and the pterosaur MPUM6009. Together they nested at the base of the Sauropterygia, largely due to the influence of the turtle.

Professional paleontolgists have a choice
They can either add the above taxa to pterosaur studies or pretend they never were born. So far, unfortunately, the latter paradigm rules.

References
Bennett SC 1996. The phylogenetic position of the Pterosauria within the Archosauromorpha. Zoo J Linn Soc118:261–309.
Brusatte SL , Benton MJ , Desojo JB and Langer MC 2010.The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida), Journal of Systematic Palaeontology, 8:1, 3-47.
Nesbitt SJ 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bulletin of the American Museum of Natural History 352: 292 pp.

Reptile Tree CI: too low? …and some thoughts from Dr. E.O. Wilson

A reader brought up the subject (he perceived it as a problem) of the very low consistency index (CI) in the large reptile tree. 340 taxa were tested against 228 characters. The reader thought too few characters were employed and that was the cause for the low CI.

The CI for the entire tree is .099. Very low, but not necessarily bad… as we shall see…

I mentioned in my reply to the reader that this was due to the high level of homoplasy in the reptile tree due to the large number of taxa sharing so many traits. I suggested the CI would rise with fewer taxa and all other variables held constant. That’s easy to do by chopping the large reptile tree apart.

Here are a few CIs focused on clades, using the same character list (228), but far fewer taxa in each case.

Watch those CI numbers rise!

All non-amniote tetrapods: .429

Captorhinids: .875

Permian/Triassic/Cretaceous gliders: .836

Rhynchocephalia (includes trilophosaurs and rhynchosaurs): .659

Tritosaurs (includes fenestrasaurs, pterosaurs): .735

Squamata: .439

Synapsida: .632

Enaliosauria (Claudiosaurus, mesosaurs, ichthyosaurs, thalattosaurs, plesiosaurs, placodonts and kin): .360

Archosauriforms: .267

Euarchosauriforms (no choristoderes, parasuchians, chanaresuchids or Lagerpeton) : .322

Archosauria (crocs and dinos): .417

Crocs: .705

Dinosauria (includes poposaurs): .523

Hope these numbers help the cause and provide understanding for the very low CI for the entire tree. The beauty of having a large tree is having the ability to easily chop it into many small trees to test various hypotheses. Unfortunately, there’s much more work for small focused trees to test larger gamuts of taxa or characters. Maybe that’s why it isn’t done.

We could always use better characters. I freely admit that some of my characters could use a little help. Some of them weight various traits, but they do it across the board. We could also use more characters, but if we add in the trait of a “carapace present” we would still end up with several convergent instances of that trait, which does nothing to increase the CI number.

It is what it is, dependent on the number of taxa employed and their rampant convergence in the large reptile tree. The data determines the results, not the other way around.

On an editorial note
A recent post engendered several irate responses from readers, most of which included negative attributions and insults. Those had to be trashed. Via private email I encouraged those readers to focus on the taxa, not the author, and make specific suggestions as to how to improve the taxon reconstructions. As you know, these then become the data that ultimately produce the family tree. Changes are made weekly. When new valid data come in, they are welcome. Readers who have no time or inclination to provide fresh data, yet find plenty of time to rant without substance, are not helping my cause or theirs. They end up frustrated. I end up wondering why they can’t provide even a little evidence. I’m led to believe those who do not provide evidence have none.

Hopefully every time I have dismissed a claim or promoted one in these 750 posts, I have provided pictorial and other evidence with references. Disregarding the evidence is your right. Choosing to support bad evidence is also your right. But those who do so run the risk of ultimately looking foolish to villainous when the tide turns. I run the risk of being wrong, but am always willing to right the wrongs. But I need fresh valid data.

I hope you all understand. I’m trying to keep this site and the data it is built upon on a professional level.

The large reptile tree has grown to where no paleontologist has gone before, conquering a larger gamut of reptiles and in doing so demystifying many relationships and former enigmas simply by being ever more inclusive. That’s a good thing, guys. Embrace it! Use it!

Some pertinent thoughts from ant expert, E. O. Wilson:
While generally lauded today, earlier in his career Dr. E. O. Wilson was reviled for some of his novel ideas*. The following Wilson quotes seem pertinent:

“Without a trace of irony I can say I have been blessed with brilliant enemies. I owe them a great debt, because they redoubled my energies and drove me in new directions.”

“Between scientists, you can have high competitiveness and jealousy and petty nit-picking, because we are human. But once something is nailed, the person who did it usually gets the credit, and we move on.” 

“But the best way to do it is – to make discoveries – is to make short imperfect experiments.” 

*(from Wikipedia)
In the water incident, Wilson’s lecture was attacked by the International Committee Against Racism, a front group of the Progressive Labor Party, where one member poured a pitcher of water on Wilson’s head and chanted “Wilson, you’re all wet” at an AAAS conference in November 1978.[38] Wilson later spoke of the incident as a source of pride: “I believe…I was the only scientist in modern times to be physically attacked for an idea.”[39]

Phylogenetic fusion patterns in pterosaurs

This post has been modified from its original content. It’s important to remember that pterosaurs are lizards. They follow lizard-type growth patterns as reported by Maisano 2002 in which some lizards fuse bones and keep growing while others never fuse certain bones into old age. Pterosaurs also grow isometrically, with long-snouted, small eyed embryos known.

Traditional thinking follows the paradigm
that the unfused scapulocoracoid (s/c) in pterosaurs demonstrates immaturity. I tested this in a phylogenetic analysis. Turns out the patterns are not ontogenetic, but clearly phylogenetic. Scapulocoracoid fusion is on again, off again in patterns that are not the random pattern one would expect if ontogenetic in nature.

 

Figure 1. Click to enlarge. Pterosaur family tree (May 2013) highlighting scapulocoracoid fusion in pterosaurs (bright green) and lack of fusion (bright blue). Other taxa do not preserve the s/c. If ontogenetic we would expect a more scattered, randomized pattern. That's not the case here as fusion patterns follow phylogeny, not maturity. Some taxa here do not preserve the scapula and coracoid. Not listed here, but related to Cearadactylus, Barbosania does not fuse the s/c. Some taxa have complete fusion. Others retain a line of fusion. Among the higher ornithocheiridae there is the greatest randomness in fusion.

Figure 1. Click to enlarge. Pterosaur family tree (May 2013) highlighting scapulocoracoid fusion in pterosaurs (bright green) and lack of fusion (bright blue). Other taxa do not preserve the s/c. If ontogenetic we would expect a more scattered, randomized pattern. That’s not the case here as fusion patterns follow phylogeny, not maturity. Some taxa here do not preserve the scapula and coracoid. Not listed here, but related to Cearadactylus, Barbosania does not fuse the s/c. Some taxa have complete fusion. Others retain a line of fusion. Among the higher ornithocheiridae there is the greatest randomness in fusion.

Pterodaustro is known from embryos to fully mature individuals
Codornú et al. (2013) report on 300+ individual specimens from a single bone bed: “Interestingly, proxies for full skeletal maturation are thus far present only in isolated elements (i.e., all complete or semicomplete specimens belong to osteologically immature individuals). These proxies include the complete fusion (lack of any sutural evidence) between the extensor tendon process and the shaft of the first wing phalanx, the complete fusion between the tibia and the proximal tarsals, and the fused distal secondary ossification centers of the humerus.” Note they did not report fusion of the scapula and coracoid. That’s because Pterodaustro nests in a clade (Fig. 1) that does not fuse the scapulocoracoid.

So what’s the pattern?
Basal pterosaurs do not have a fused scapulocoracoid. Dimorphodon may have a fused s/c. Campyognathoides and basal Dorygnathus fuse the s/c. Basal Rhamphorhynchus specimens are smaller and lack fusion. Derived Rhamphorhynchus regain fusion. Dorygnathid pre-azhdarchids beginning with tiny TM 10341 lose fusion. Large azhdarchids regain fusion. No ctenochasmatid or dorygnathid pre-ctenochasmatid fuse the scapulocoracoid. Jianchangnathus and all subsequent scaphognathids lose fusion. Basal ornithocheirds, no matter how large their wings are do not fuse the s/c. Certain, but not all derived ornithocheirds regain fusion. On another branch of scaphognathids, certain germanodactylids regain fusion. Shenzhoupterids and basal tapejarids lose fusion. Derived tapejarids, the big ones, regain fusion. (Does anyone have a good dsungaripterid scapulocoracoid? I haven’t seen one yet.) Germanodactylids including Pteranodon have fusion (not sure about basal taxa because so many are known just by skulls), but eopteranodontids and nyctosaurs lack scapulocoracoid fusion.

A little pterosaur referred to Eudimorphodon, BsP 1994 has a fused s/c. Arthurdactylus a much larger, longer winged ornithocheirid, does nto fuse the s/c. So size is not the issue.

All known pterosaur embryos come from clades that do not fuse the scapulocoracoid. However, the  juvenile Pteranodon has a fused s/c.

Addendum
Once a clade began to fuse the s/c, then lack of fusion generally accompanied phylogenetic size reductions. Among azhdarchids, only Quetzalcoatlus fuses the s/c. This includes a smaller Pteranodon YPM2525 which may also represent a size reduction shown here.

Among the derived ornithocheirds you do get a more randomized on-off-on-off pattern.

So there you have it. All results subject to change with injections of new valid data.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Maisano JA 2002. The potential utility of postnatal skeletal developmental patterns in squamate phylogenetics. Journal of Vertebrate Paleontology 22:82A.
Maisano JA 2002. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.

DNA vs. Morphology in Reptiles and Living Things

I’m always harping on taxon inclusion and the importance of large taxon lists –especially when you don’t have large studies to base your more focused studies on.

I recently came across the gigantic family tree (Fig. 1) of living things based on DNA by David Hillis. There are so many taxa that the individual listings are not visible unless the PDF is enlarged to about 54 inches in width. Carl Zimmer of Discover Magazine interviewed Hillis here.

The Dave Hillis tree of all living things.

Figure 1. The Dave Hillis tree of all living things.

Here’s the tree pruned to the vertebrates and colorized for simplification. Yes, its only a few degrees on the circle.

Segment from the David Hillis tree of life showing vertebrates. Here the mammals (ant their ancestors) were the first amniotes to branch off, confirming traditional thinking and countering the large reptile tree which shows mammals on the lineage toward archosaurs.

Figure 2. Segment from the David Hillis tree of life showing vertebrates. Here the mammals (ant their ancestors) were the first amniotes to branch off, confirming traditional thinking and countering the large reptile tree which shows mammals on the lineage toward archosaurs.

The Hillis Tree is both more inclusive (with bacteria, fungi and plants) and less inclusive (no extinct taxa, very few living vertebrates). Even so, the resulting tree echoes traditional vertebrate trees in finding mammals (synapsids) as the first of the living clades to branch off from the other amniotes. This is different from the large reptile tree which shows the basal diapsids that gave rise to archosaurs were derived from the basal synapsids that gave rise to mammals.

So, it’s morphology vs. DNA.
Most of the time morphology agrees with DNA in the large reptile tree and the Hillis tree. Only at one point are they distinct. This is troublesome as with living taxa DNA rules, but with extinct taxa morphology rules (no DNA).

The Origin of Archosaurs and/or Archosauriformes
The literature includes papers on the origin of Archosaurs and Archosauriformes, usually originating with Proterosuchus and Archosaurus. Fewer papers look deeper into time, finding the outgroup to these taxa in protorosaurs. Fewer still look yet deeper into time, finding the outgroup to protorosaurs in Younginiformes. Wiki reports, “Younginiformes (including AcerosodontosaurusHovasaurusKenyasaurusTangasaurusThadeosaurusYoungina, et alia sensu Currie and other researchers in the 1980s) is probably not a clade. It appears to represent a grade of South African Permo-Triassic diapsids that are not more closely related to each other as a whole than they are to other reptiles.” Indeed these taxa do form a grade in the large reptile tree.

Palaeos.com reported, “the in-group relationships of “Younginiformes,” as well as their monophyletic status, are neither understood nor have they been tested in a modern phylogenetic framework.”

So, at this point on the reptile tree, things are getting murky in the literature. That’s why the large reptile tree exists, to test previously untested relationships and establish new topologies.

DNA has also linked turtles to archosaurs, and there’s no morphological correlate there. At least no one has announced one.

Platypus skeleton at Melbourne Museum.

Figure 3. Click to enlarge. Platypus skeleton at Melbourne Museum. Photo credit: w:User:Pengo from Wikipedia.

Then there’s the Platypus (Ornithorhychus anatinus)
The Guardian reported on a recent DNA study of an egg-laying mammal “While humans have two sex chromosomes, the X and Y, the platypus has 10, with five of each kind.” The new study, published in Nature (2008), shows the platypus as both evolutionary relic and pioneer. Chris Ponting, at the Medical Research Council’s functional genomics unit at Oxford University, said scientists had had the first chance to see if the platypus’s weird appearance was reflected in its DNA: “Lo and behold, we saw genes like those in lizards and birds, as well as some like those in other mammals. It has retained many genes other mammals lost from a time when all mammals looked much like lizards.”

Hedges 1993
Hedges (1993) reported, “This classical phylogeny of amniotes has been challenged
by recent morphological studies of living forms. Traits such as a single aortic trunk, folded cerebellum, scroll-like turbinals, loop of Henle (kidney), adventitious cartilage, and endothermy are found only in birds and mammals and have been proposed as evidence for a close relationship. Analyses of fossil and recent morphological data indicated that support for a bird-crocodilian relationship rests primarily on the fossil data, and specifically with some mammal-like reptile fossils that place mammals at the base of the amniote tree. Molecular sequence data from three genes (myoglobin, (3hemoglobin, 18S rRNA) have supported a bird-mammal grouping, but sequence data from several other genes have not. These conflicting results have created uncertainty about our ability to resolve amniote phylogeny.” Ultimately Hedges recovered a vertebrate tree echoing the Hillis tree (Fig. 1), which echoes traditional thinking based on small prior studies.

So why don’t birds and crocs nest with mammals in DNA tests?
I’m stymied. Perhaps the platypus can tell us why. It’s venom DNA is most like that of venomous snakes, yet is clearly not related. Perhaps mammals are just that different and have been since the days of the basal therapsids. This is the prime mystery initiated by, rather than solved by the larger reptile tree.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Hillis DNA Tree of Living Things

Testing Hill 2005

N.  Brocklehurst wrote,
“I think your repeated assertion that palaeontologists don’t test the relationships you suggest is a bit…well its just not true. Admittedly some havn’t been tested e.g. Tetraceratops (never tested outside synapsids), but a great many have. As just one example Hill (2005) uses a (mostly) genus-level taxon list which covers 80 taxa from almost all the major groups in Amniota with charater list almost 3 times the size of yours to show that Caseids do not go with Milleretids and Bolosaurids, Rhynchosaurs do not go with Rhynchocephalians, Ophiacodontids are not the sister to Therapsids, Synapsids do not go with Archosaurs, Captorhinids do not go with Lepidosaurs, Mesosaurids do not go with marine reptiles…I could go on.”

This is a topic worthy of a post. Coincidentally and several years ago I had studied Hill (2005) and submitted a manuscript describing its faults. It was rejected.

What Hill (2005) was looking for and how he did it
Hill (2005) sought to determine the phylogenetic position of turtles within the Amniota by increasing taxonomic sampling and including integumentary characters, like scutes on glyptodons and sauropods. Strange, mixing such taxa, only because they had scutes. But it was published, so hats off to Hill.

As in all supermatrices, no effort was made by Hill to cull the data or study the taxa. The data was presented ‘as is.’ Hill (2005) reported, “The morphological data set assembled here represents the largest yet compiled for Amniota.” He concluded with, “Turtles are here resolved as the sister taxon to a monophyletic Lepidosauria (squamates + Sphenodon), a novel phylogenetic position that nevertheless is consistent with recent molecular and morphological studies that have hypothesized diapsid affinities for this clade.”

I tested Hill (2005) back in 2006 (long before ReptileEvolution.com) in a three-step process.

1. Taking Hill (2005) as is. 
Hill 2005 created a supermatrix by combining published data and new data based on osteology and histology of the integument. Some strange pairings resulted (Fig. 1). Bulky Diadectomorpha nested as sisters to lithe marine Mesosauridae and as sister taxa to the Synapsida. None of these look very much alike. Round-faced Acleistorhinus nested with flat-faced Lanthanosuchus. Short-faced Trilophosaurus nested with long-faced Choristodera (Champsosaurus). The so-called ‘rib’ gliders nested with marine Sauropterygia. Turtles nest with Sphenodon and both are the sister taxa to Archosauria (dinos + crocs + parasuchia + aetosaurs). Parasuchians nest within aetosaurs. Aetosaurs nest within crocodylomorphs, derived from Protosuchus. Other than these misfits, the rest ain’t too bad. And we can’t blame Hill for this because, true to the method, he was just pulling together published trees (but without casting a critical eye on the data).

To one of Neil Brocklehurst points, note the sphenacodonts and basal therapsids are suprageneric in Hill (2005), so there was the opportunity for some cherry-picking of traits and key taxa. Stenocybus. a key taxon, was not included.

Hill 2005. See text for details.

Figure 1. Hill 2005. See text for details. Suprageneric taxa are marked by black squares.

2. Hill 2005 revision #1
A thorough examination of Hill’s data matrix revealed that hundreds of blank matrix boxes could be scored. Hundreds of others could be more accurately rescored, sometimes with additional character states to more accurately reflect characters. Since this was a supertree compilation, such a critical eye was not part of Hill’s process or method. I don’t like to let things slide.

Taxa that were difficult to access and contributed to excess polytomies using Hill’s scoring, such as Coahomasuchus, the titanosaur sauropods, Glyptosaurinae, Akanthosuchus, Goniopholis, Simosuchus and Mahajangasuchus were deleted. None of these taxa are basal to their respective clades.

Characters that were difficult to determine (foramina, braincase, notochordal opening) were left as Hill’s predecessors had scored them.

The resulting cladogram (Fig. 2) shows more appropriate tree topology with most clades in a more reasonable (more parsimonious) order (sister taxa look more alike overall and in detail), but pareiasaurs and turtles still nest here between lizards and Crurotarsi, which appears untenable.

 Hill (2005) revised.

Figure 2. Hill (2005) revised by the addition of more character scores. Note the topology changes.

3. Hill 2005 revision #2
The addition of a just few taxa (in red) to Hill (2005) revision #1 (Fig. 3) recovers a tree topology very much like the large reptile tree, including the major dichotomy at the base of the Reptilia (a hypothesis totally unknown to Hill in 2005). This underscores the importance of a wide gamut in a taxon list when exploring untested relationships. Here turtles nest with pareiasaurs, Procolophon and other lepidosauromorphs. Casea nests with Millerettidae, far from the Synapsida. Kuehneosaurus nests with similarly-shaped arboreal Lepidosauriformes. Synapsids and mesosaurs nest with sauropterygians and archosauriforms.

Adding taxa to the revision of Hill (2005).

Figure 3. Adding taxa to the revision of Hill (2005). Still not perfect, but a lot better.

It’s worthy to note that
the large reptile tree does not include any glyptodonts, derived crocodylomorphs or very many ornamented lizards. Instead the large reptile tree used more basal taxa to establish a wider gamut of relationships, leaving the above-mentioned highly derived taxa for other more focused studies.

It is also worthy to note that
even with so few taxa, and largely using Hill’s characters, the reptile tree dichotomy was recovered.

To Neil’s point about the Hill (2005) 3x larger character list
Once again: It’s the taxon list (not the number of characters) that needs to expand to figure out the amniote tree topology. As an example, see what just a few extra taxa can do to a tree? (Fig. 3). Any number of characters over 150 tends to flatten out the results from 95% consistency to 98% to 98.5% to 99.1%, never quite reaching, but very closely approaching 100%. On the other hand, every additional taxon provides an additional opportunity for any already included taxon to find a more parimonious partner somewhere on the tree. The larger the list, the better.

Assertion?
No. I tested that sucker. This is evidence.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Hill RV 2005. Integration of Morphological Data Sets for Phylogenetic Analysis of Amniota: The Importance of Integumentary Characters and Increased Taxonomic Sampling. Systematic Biology 54(4):530–547.