Colobops and taxon exclusion issues

Too often workers fail to include the closest relatives of new specimens
in analysis and then report they have something new and different in the pantheon of tetrapods. Too often the analysis lacks the correct tree topology, also due to taxon exclusion.

The new genus, Colobops noviportensis
(Pritchard, Gauthier, Hanson, Bever and Bhullar 2018; Fig. 1) was described as a tiny (2.5 cm long skull) saurian reptile from the Triassic of Connecticut, USA. Taxonomically it suffers from taxon exclusion. It was nested by default because more closely related taxa were omitted from a previously published analysis (Pritchard and Nesbitt 2017; Fig. 2), which was an inadequate analysis to work from because it failed to show the basal dichotomy of the Reptilia (Lepidosauromorpha/Archosauromorpha; Fig. 3) revealed by increasing the number of taxa.

Figure 1. Colobops as originally presented and slightly restored.

Figure 1. Colobops as originally presented and slightly restored. Glad to see other workers are coloring bones or identification. These are from CT scans. The postorbital processes invading the supratemporal fenestrae are unique.

From the abstract
“The taxon possesses an exceptionally reinforced snout and strikingly expanded supratemporal fossae for adductor musculature relative to any known Mesozoic or Recent diapsid of similar size. Our phylogenetic analyses support C. noviportensis as an early diverging pan-archosaur. Colobops noviportensis reveals extraordinary disparity of the feeding apparatus in small-bodied early Mesozoic diapsids, and a suite of morphologies, functionally related to a powerful bite, unknown in any small-bodied diapsid.”

Figure 2. Marmoretta, a basal rhynchocephalian in the lineage of pleurosaurs

Figure 2. Marmoretta, a basal rhynchocephalian in the lineage of pleurosaurs. Note the variety in the size of the supratemporal (upper) fenestrae, a variety that expands with Colobops.

Unfortunately,
their phylogenetic analysis (Fig. 3) did not include the basal sphenodontid, Marmoretta, more similar to Colobops in the large reptile tree (LRT, 1085 taxa; subset Fig. 4) than any other tested taxon. They are also the same size.

Figure 3. Cladogram from Pritchard et al. failed to include a long list of basal sphenodontians, including Marmoretta, the sister to Colobops in the LRT. Note the shuffling of lepidosauromorph and archosauromorphs in this cladogram, lacking any broad resemblance to the LRT tree topology.

Figure 3. Cladogram from Pritchard et al. failed to include a long list of basal sphenodontians, including Marmoretta, the sister to Colobops in the LRT. Note the shuffling of lepidosauromorph and archosauromorphs in this cladogram, lacking any broad resemblance to the LRT tree topology. Pritchard et al. assume that diapsids are monophyletic, which dooms their analysis. There is so much taxon exclusion here.

Marmoretta oxoniensis (Evans 1991, Waldman and Evans 1994) Middle/Late Jurassic, ~2.5 cm skull length, orginally considered a sister of kuehneosaursdrepanosaurs and lepidosaurs. Here Marmoretta was derived from a sister to Megachirella and PalaegamaMarmoretta was basal to Gephyrosaurus and the rest of the Sphenodontia = Rhynchochephalia. Two specimens are known (Fig. 2) with distinct proportions in the skull roof (frontal and parietal, see above). Note the variety in the supratemporal fenestrae in these closely related tiny flat-headed taxa, including Colobops.

By the way,
the Wikipedia page on Marmoretta likewise suffers from taxon exclusion.

Figure 5. Cladogram of the Sphenodontia includes Colobops and rhynchosaurs.

Figure 4. Cladogram of the Sphenodontia includes Colobops and rhynchosaurs.

Pritchard et al. assumed the monophyly of the Diapsida
which doomed their cladogram to a shuffling of disparate morphologies and by-default nestings (Fig. 3). Several years ago the LRT split the Archosauromorpha from the Lepidosauromorpha at the origin of the Reptilia, and so revealed that the diapsid skull architecture evolved at least twice.

Pritchard et al. nested Colobops
at the base of the Rhynchosauria due to taxon exclusion. In the LRT (subset Fig. 4) rhynchosaurs and Colobops are separated by a long list of taxa. The authors reported, “Two additional steps produce topologies in which C. noviportensis occupies some positions with pan-Archosauria and a position nested within Sphenodontia, a clade that converged anatomically on rhynchosaurs in numerous skull characters.”

If only
Pritchard et al. had used more taxa (or the LRT) they would have known that sphenodontids did not converge with rhynchosaurs, they were basal to rhynchosaurs. The authors report, “Colobops noviportensis represents a combination of morphological traits unknown in extant amniotes, and thus a morphology that would not have been reconstructed in a macroevolutionary analysis based exclusively on extant species.” I don’t see the extant tuatara, Sphenodon. in their taxon list.

Colobops lacks teeth
and lacks alveoli as well. The authors report, “The best insights into the feeding of C. noviportensis come from the general shape of the adductor chamber. In C. noviportensis, the post-temporal process of the parietal is oriented laterally, as in Sphenodontia and Rhynchosauridae, rather than posterolaterally as in most pan-lepidosaurs and pan-archosaurs.” See how they were just peeking in at the insights revealed by the LRT? Yet they followed tradition and previously published phylogenetic analyses beset with problems from the start.

The adductor chambers for jaw muscles in Colobops
are indeed quite large. And the postorbital process that invades the supratemporal fenestra is unique (at present). Sister sphenondontids do not have such a large supratemporal fenestra until Sphenodon. Note that one of the Marmoretta specimens (Fig. 2) had developed a parietal crest, also for the enlargement of the jaw muscles. So they were trying various ways to do this.

Based on the similar sizes of the marmorettid skulls
the skull of Colobops probably represents an adult.

The authors report
“Within individual species, overall skull size appears to correlate strongly with the relative breadth of the adductor chamber; juveniles recapitulate the transition from Permian Diapsida to crown-group with a small supratemporal fossa with small proportionally modest embayments on the parietal giving way to proportionally larger fossae and deeper parietal embayments.” Good to know. Irrelevant in this case.

I’m happy to see these authors have colorize key bones
throughout their paper. That’s the best way to illustrate them.

The final takeaway:
No matter how many co-authors you have with PhDs… no matter how many diagrams you show… no matter how many irrelevant taxa you include… no matter if you have firsthand access to the specimen… no matter if you are published in Nature… if you exclude the most closely related taxa, you’re going to let bloggers report your most basic errors. The LRT is online in order to be freely used. Use it. It’s a good starting point for any new taxon because it minimizes the opportunity for taxon exclusion by including so many taxa.

References
Evans SE 1991. A new lizard−like reptile (Diapsida: Lepidosauromorpha) from the Middle Jurassic of Oxfordshire. Zoological Journal of the Linnean Society 103:391-412.
Pritchard AC and Nesbitt SJ. 2017. A bird-like skull in a Triassic diapsid reptile increases heterogeneity of the morphological and phylogenetic radiation of Diapsida. Royal Society Open Science 4, 170499
Pritchard AC, Gauthier JA, Hanson M, Bever GS and Bhullar B-AS 2018. A tiny Triassic saurian from Connecticut and the early evolution of the diapsid feeding apparatus. Nature Communications open access DOI: 10.1038/s41467-018-03508-1
Waldman M and Evans SE 1994. Lepidosauromorph reptiles from the Middle Jurassic of Skye. Zoological Journal of the Linnean Society 112:135-150.

wiki/Marmoretta

 

 

You heard it here first: Orovenator had diapsid AND varanopid traits—for good reason!

This is a YouTube video of a
talk given by postgraduate David Ford recorded at The 65th Symposium on Vertebrate Palaeontology and Comparative Anatomy, University of Birmingham. His incredibly detailed  observations found diapsid traits AND varanopid traits, which was cause for consternation. Click to view.

Ford used µCT data
to recover in Ororvenator what the large reptile tree (LRT, 1181 taxa) was able to recover from published drawings. Ford nested Orovenator and Synapsida within Diapsida. Although heretical, that’s not the correct solution when you add more pertinent taxa.

By contrast, in the LRT
basal synapsids split at their genesis between Synapsida and Prodiapsida following Vaughnictis, another late-surviving taxon. Ford was unaware of that split at the time. In the LRT, late-surviving early Permian Orovenator was derived from basal synapsids (varanopids) AND ancestral to basal diapsids like Petrolacosaurus in the Late Carboniferous.

We looked at Orovenator relationships earlier
here in 2014 and here in 2017. Key to testing any taxonomic relationships is appropriate taxon inclusion. Let’s hope Ford has expanded his taxon inclusion set appropriately when the paper comes out. He’s got a good handle on the details, but the big picture evidently was not in his ken due to the exclusion of pertinent taxa.

Figure 2. The Prodiapsida now include the holotypes of Ascendonanus and Anningia.

Figure 2. The Prodiapsida now include the holotypes of Ascendonanus and Anningia.

Pteranodon quad hopping water takeoff, according to the AMNH

Hopefully this is going to be the last time
the American Museum of Natural History embarrasses itself with bogus pterosaur tricks. We looked at problems from the original 2014 AMNH pterosaur display here and elsewhere. Evidently they have decided to stop using math, physics and modern analogs, alas, to their disgrace… while cartooning (Fig. 1) the bird-like pterosaurs under the guise of a scientific exhibition.

Figure 1. GIF animation from the American Museum of Natural History showing how their Pteranodon managed to hop off the surface of the water until suddenly able to flap and fly. Totally bogus.

Figure 1. GIF animation from the American Museum of Natural History showing how their Pteranodon managed to hop off the surface of the water until suddenly able to flap and fly. Totally bogus. It won’t develop any lift or thrust with wings folded. …Unless Pteranodon was filled with helium?? Those deep chord wing membranes are likewise not preserved in any fossil. 

Above is how the American Museum of Natural History
(AMNH) imagines the takeoff of Pteranodon from calm seas (Fig. 1, AMNH webpage). Not credible. Not accurate, either with those deep chord wing membranes, not yet found in any fossils.

Pelican take-off sequence from water.

Figure 2. Pelican take-off sequence from water. Click to enlarge.

Above is how the living pelican
(Pelecanus) actually takes off from gulf waters (Fig. 2 and YouTube video above it in slow motion, click to view). The Pteranodon-like pelican lifts its great wings out of the water to develop lift and thrust. Ground effect keeps it out of the water after one flap. Water is where drag occurs. And legs kicking or hopping has never lifted any pelican out of the water. The wings, fully extended as taut airfoils, do 99% of the work. The foot hops off of wave tops after flight has been initiated, are negligible thrust producers.

Figure 3. Triebold Pteranodon in floating configuration. Center of balance marked by cross-hairs.

Figure 3. Triebold Pteranodon in floating configuration. Center of balance marked by cross-hairs.

Above is how ReptileEvolution.com
imagines Pteranodon floating on the sea (Fig. 4) using its air-filled wing bones as lateral floatation devices. The torso and skull were also lighter than an equal volume of water, as in all floating birds.

Pterosaur water launch

Figure 4. Ornithocheirid water launch sequence in the pattern of a pelican launch. LIke ducks, geese and pelicans, pterosaur probably floated high in the water. Here the wings rise first and unfold in an unhurried fashion, keeping dry and unencumbered by swirling waters. Then the legs run furiously, like a Jesus lizard, but with such tiny feet, they were not much help in generating forward motion. The huge wings, however, did create great drafts of air, thrusting the pterosaur forward until sufficient airspeed was attained, as in the pelican.

Earlier we looked at several water take-off scenarios
for pterosaurs using Anhanguera as a model (Fig. 4). Keep those wings out of the water where they can develop thrust and lift with full extension and taut membranes. A sagging wing membrane (Fig. 1) develops neither lift nor thrust.

Successful heretical bird-style Pteranodon wing launch

Figure 5. Click to play. Successful heretical bird-style Pteranodon wing launch in which the hind limbs produce far less initial thrust because the first downstroke of the already upraised wing provides the necessary thrust for takeoff in the manner of birds. This assumes a standing start and not a running start in the manner of lizards. Note three wing beats take place in the same space and time that only one wing beat takes place in the Habib/Molnar model. Compare to a similar number of wingbeats in the pelican.

Above is how the heretical hypothesis
imagines the takeoff of Pteranodon from the ground (Fig. 4): just like a crane, pelican or other large bird. For a water takeoff, just add water and keep the wings off the surface. Flapping so close to the water takes advantage of ‘ground effect’ where lift is increased when the wing is close to the ground.

By contrast,
either the AMNH model is made of helium or hung on a string, or the sea is made of jello, because against all laws of physics somehow those tiny fingers and feet are keeping the head and torso above the watery surface. If anyone can defend the AMNH scenario, please make comment below.

Just found out: The quad fly hypothesis goes back to 1943!
Daffy Duck in “To Duck or Not to Duck” was using the quad style to fly (Fig. 6) back in 1943, just before Elmer Fudd fired a shotgun at him. Compare this technique to Pteranodon in figure 1 and you’ll see convergence on a massive scale.

Figure 8. Daffy Duck in "To Duck or Not to Duck" 1943 uses the quad fly method. See figure 1 for comparable take-off technique.

Figure 8. Daffy Duck in “To Duck or Not to Duck” 1943 uses the quad fly method. See figure 1 for comparable take-off technique.

At the AMNH
Dr. Mark Norell, curator and chair of the Museum’s Paleontology Division, oversaw the pterosaur exhibition with Dr. Alexander Kellner of Museu Nacional in Rio de Janiero.

 

 

Sylviornis: Not a megapode. Not a ratite. Not a giant stem chicken…

In the large reptile tree (LRT, 1080 taxa) the giant recently extinct bird from New Caledonia, Sylviornis (Poplin 1980) nests with basal hook-beak predatory birds, like the seriema (Cariama), the secretary bird (Sagittarius) and the terror birds, like Phorusrhacos.

Figure 1. Sylviornis is not a giant chicken. It's a basal predatory bird.

Figure 1. Sylviornis is not a giant chicken. It’s a giant secretary bird.

It’s a different kind of terror bird
on a small island east of Australia. It was originally considered a ratite, then a megapode, then a stem chicken (Gallus) not quite a meter in length. The premaxilla forms a crest. The narrow rostrum is mobile relative to the wide cranium.

Worthy et al 2016 reported,
“Osteology Supports a Stem-Galliform Affinity for the Giant Extinct Flightless Bird Sylviornis neocaledoniae (Sylviornithidae, Galloanseres).”

Due to convergence,
be very wary of osteology determining relationships. Only cladograms determine relationships. In this case, the authors excluded Cariama and Sagittarius, proximal sisters to Sylviornis in the LRT.

References
Poplin F 1980. Sylviornis neocaledoniae n. g., n. sp. (Aves), ratite éteint de la Nouvelle-Calédonie”. Comptes Rendus de l’Académie des Sciences, Série D (in French). 290: 691–694.
Mourer-Chauviré C and Balouet JC 2005. Description of the skull of the genus Sylviornis Poplin, 1980 (Aves, Galliformes, Sylviornithidae new family), a giant extinct bird from the Holocene of New Caledonia. In Alcover, J. A.; Bover, P. Proceedings of the International Symposium “Insular Vertebrate Evolution: the Palaeontological Approach”. Monografies de la Societat d’Història Natural de les Balears. 12. pp. 205–218.
Worthy TH et al. 2016. Osteology Supports a Stem-Galliform Affinity for the Giant Extinct Flightless Bird Sylviornis neocaledoniae (Sylviornithidae, Galloanseres). PLoS ONE 11(3): e0150871. doi:10.1371/journal.pone.0150871

wiki/Sagittarius
wiki/Llallawavis
wiki/Phorusrhacos
wiki/Sylviornis

Müller et al. discuss Lagerpeton ‘sisters’ without Tropidosuchus

Müller, Langer and Dias da Silva (2018) report:
“Despite representing a key-taxon in dinosauromorph phylogeny, Lagerpertidae is one of the most obscure and enigmatic branches from the stem that leads to the dinosaurs.”
It’s taxon exclusion, yet again.
Lagerpeton (Fig. 1) is obscure and enigmatic because it is NOT in the stem that leads to dinosaurs. We discussed that earlier here in 2011. Langer is aware of the better, more inclusive, option because he sent me the reference for Novas and Agnolin 2016 discussed here.
“Recent new findings have greatly increased our knowledge about lagerpetids, but no phylogenetic analysis has so far included all known members of this group. Here, we present the most inclusive phylogenetic study so far conducted for Lagerpetidae. …Finally, quantification of the codified characters of our analysis reveals that Lagerpetidae is one of the poorest known among the Triassic dinosauromorph groups in terms of their anatomy, so that new discoveries of more complete specimens are awaited to establish a more robust phylogeny.”
Tropidosuchus is known from complete skeletons (Fig. 1) and is the sister to Lagerpeton in the more inclusive large reptile tree (LRT, 1173 taxa).
Problem solved!
Figure 3. The closest kin of Tropidosuchus are the much larger Chanaresuchus (matching Nesbitt 2011) and the smaller Lagerpeton.

Figure 1. The closest kin of Tropidosuchus are the much larger Chanaresuchus (matching Nesbitt 2011) and the smaller Lagerpeton.

Ixalerpeton
Müller et al. nest Ixalerpeton (Fig. 24) with Lagerpeton without testing other candidates. In the LRT Ixalerpeton nests among basal protorosaurs, far from Lagerpeton. And yes, it might have been the only bipedal protorosaur, exciting news that was completely overlooked due to taxon exclusion. Or not. The foot would be helpful, but is not known.
Figure 2. Ixalerpeton bits and pieces reconstructed. This taxon nests with protorosaurs.

Figure 2. Ixalerpeton bits and pieces reconstructed. This taxon nests with protorosaurs.

Which protorosaur was closest to Ixalerpeton?
Ixalerpeton nests between the AMNH 9502 specimen of Prolacerta and Czatkowiella, (Fig. 3), taxa omitted by the Müller et al. 2018 study.

Figure 1. Czatkowiella harae bits and pieces here reconstructed as best as possible. Note the size difference here between the large maxilla and the small one.

Figure 3. Czatkowiella harae bits and pieces here reconstructed as best as possible. Note the size difference here between the large maxilla and the small one. This taxon is close to Ixalerpeton. The skull roof and occiput are comparably similar.  Perhaps Ixalerpeton had a longer neck based on this sister.

References
Müller RT,  Langer  MC & Dias-Da-Silva  S 2018. Ingroup relationships of Lagerpetidae (Avemetatarsalia: Dinosauromorpha): a further phylogenetic investigation on the understanding of dinosaur relatives. Zootaxa 4392(1): 149â158
Novas FE and Agnolin FL 2016 Lagerpeton chanarensis Romer (Archosauriformes): A derived proterochampsian from the middle Triassic of NW Argentina. Simposio. From Eventos del Mesozoico temprano en la evolución de los dinosaurios”. Programa VCLAPV. Conferencia plenaria: Hidrodinámica y modo de vida de los primeros vertebrados. Héctor Botella (Universitat de València, España) 2016

The Early Permian Ascendonanus assemblage

There are five specimens from the same pit
that were assigned to the varanid taxon Ascendonanus. Spindler et al. 2018 thought they were all conspecific.

Given their distinct proportions
(Fig. 1) and the phylogenetic differences recovered in 2 of the 5 so far (earlier one nested as a basal iguanid), we’re going to need some new generic names for at least one of the referred specimens. The others have not yet been tested in the large reptile tree (LRT, 1179 taxa).

The holotype
remains Ascendonanus, but here it’s no longer a varanopid synapsid. Here it nests as a derived prodiapsid and the basalmost tested diapsid (Fig. 2), a little younger than the oldest diapsid, Petrolacosaurus.

Figure 1. The five specimens from the Ascendonanus quarry, all to the same scale. Most images from Spindler et al. 2018. Some have skulls 3x the occiput/acetabulum length. Others as much as 5x, the first hint that these taxa are no conspecific.

Figure 1. The five specimens from the Ascendonanus quarry, all to the same scale, counter plate flipped in every specimen. Most images from Spindler et al. 2018. Some have skulls 3x the occiput/acetabulum length. Others as much as 5x, the first hint that these taxa are no conspecific.

Some of these specimens
(Fig. 1) have an occiput/acetabulum length distinct from the others, ranging from 3x to 5x the skull length, the first clue to their distinct morphologies.

Figure 2. The Prodiapsida now include the holotypes of Ascendonanus and Anningia.

Figure 2. The Prodiapsida now include the holotypes of Ascendonanus and Anningia. Remember, the Diapsida does not include any Lepidosauriforms, which nest elsewhere.

Spindler et al. 2018
did not include several taxa typically included in pelycosaur studies and should not have included any caseasaurs, despite their traditional inclusion. Spindler et al. did not include any diapsids nor did they understand the role of the former varanopids now nesting as ancestors to the Diapsida (sans Lepidosauriformes).

Figure 3. Cladogram from Spindler et al. 2018. Colors refer to clades in the LRT.

Figure 3. Cladogram from Spindler et al. 2018. Colors refer to clades in the LRT.

The holotype 0924 specimen has more of a varanopid skull
than the 1045 specimen we looked at earlier. Prodiapsid sisters include varanopids ancestral to synapsids. Prodiapsids, as their name suggests, are late-surviving ancestors to diapsids like the coeval Araeoscelis (Early Permian) and the earlier Spinoaequalis (Late Carboniferous).

Figure 3. The Ascendonanus holotype skull as originally traced and as traced here.

Figure 3. The Ascendonanus holotype skull as originally traced and as traced here. Whether an upper temporal fenestra was present (as shown in the color tracing), or not (as shown in the drawings, makes no difference as this taxon nests at the transition. 

Not sure yet
where the other three specimens assigned to Ascendonanus nest. Enough muck stirred for the moment.

References
Rößler R, Zierold T, Feng Z, Kretzschmar R, Merbitz M, Annacker V and Schneider JW 2012. A snapshot of an early Permian ecosystem preserved by explosive volcanism:
New results from the Chemnitz Petrified Forest, Germany. PALAIOS, 2012, v. 27, p. 814–834.
Spindler F, Werneburg R, Schneider JW, Luthardt L, Annacker V and Räler R 2018. First arboreal ‘pelycosaurs’ (Synapsida: Varanopidae) from the early Permian Chemnitz Fossil Lagerstätte, SE Germany, with a review of varanopid phylogeny. DOI: https://doi.org/10.1007/s12542-018-0405-9

Problems in the reevaluation of Caseosaurus

Baron and Williams 2018
bring us a new evaluation of a Late Triassic ilium considered to be an enigmatic (because nothing more than an illiim is known) dinosauriform, Caseosaurus crosbyensis.

From their abstract
“Historically, Caseosaurus crosbyensis has been considered to represent an early saurischian dinosaur, and often a herrerasaur. More recent work on Triassic dinosaurs has cast doubt over its supposed dinosaurian affinities and uncertainty about particular features in the holotype and only known specimen has led to the species being regarded as a dinosauriform of indeterminate position. Here, we present a new diagnosis for Caseosaurus crosbyensis and refer additional material to the taxon—a partial right ilium from Snyder Quarry. Our comparisons and phylogenetic analyses suggest that Caseosaurus crosbyensis belongs in a clade with herrerasaurs and that this clade is the sister taxon of Dinosauria, rather than positioned within it.”

Unfortunately
in order to determine which taxa are in and out of the Dinosauria and the Archosauria, you have to include basal bipedal crocodylomorphs, the outgroup for the Dinosauria in the large reptile tree (LRT, 1176 taxa). Baron and Williams omit this vital clade and so come up short in their evaluation. Baron recently made waves when he united Ornithischia with Theropoda to the exclusion of Sauropodomorpha. That error was also due to taxon exclusion, covered earlier here and here.

Worse yet, the authors report, 
“In addition, our analysis recovers the enigmatic European taxon Saltopus elginensis among herrerasaurs for the first time.”

Hopefully that will be the first and only time.
In the LRT, Saltopus nests with Scleromochlus and Gracilisuchus as basal crocodylomorphs.” Again, this is due to taxon exclusion.

Worst yet, the authors report,
Dimorphodon macronyx was included as an additional outgroup taxon, following its use in the study by Baron et al. (2017a).”

Hopefully this will be the last time
pterosaurs are used in dinosaur phylogenetic analysis. They are not related to each other.

Building on these fails, the authors continue:
“If this hypothesis is correct then this clade of herrerasaurs also represents the first clade of non-dinosaurian dinosauromorphs known to contain large-bodied carnivorous species.”

This hypothesis is not correct.
In the LRT, Herrerasaurus and kin nest as the last common ancestor of all dinosaurs, and so, by definition, Herrerasaurus and kin are dinosaurs, basal carnivorous dinosaurs. Based on the proximity of basal bipedal crocs to dinosaurs, there are no known non-dinosaur dinosauromorphs at this time. The Dinosauromorpha is a junior synonym for Archosauria and should be dropped from usage.

And now, the big reveal:
We only know the ilium from Caseosaurus, the holotype UMMP 8870 and the referred material NMMNH P-35995. Are they conspecific? No (Fig 1). Are they congeneric? No.

Figure 1. GIF animation comparing the holotype pelvis of Caseosaurus (big and red) to the referred material (small and blue). Perhaps you are asking yourself, what were these authors thinking? The two pelves are not even congeneric.

Figure 1. GIF animation comparing the holotype pelvis of Caseosaurus (big and red) to the referred material (small and blue). Perhaps you are asking yourself, what were these authors thinking? The two pelves are not even congeneric.

Presently in the LRT
the PVL 4597 specimen (Fig. 2, wrongly attributed to Gracilisuchus) nests as the last common ancestor of dinos and crocs. That’s what the ilium looks like compared to the basalmost dino, Herrerasaurus (Fig. 2).

Figure 1. The PVL 4597 specimen attributed to Gracilisuchus by Lecuona et al. 2017, but nesting at the base of the Dinosauria in the LRT.

Figure 1. The PVL 4597 specimen attributed to Gracilisuchus by Lecuona et al. 2017, but nesting at the base of the Dinosauria in the LRT.

According to Wikipedia
Langer (2004) examined the ilium and reassigned it to the genus Chindesaurus, which lived during the same period and geological region.

References
Baron MG and Williams ME 2018. A re-evaluation of the enigmatic dinosauriform Caseosaurus crosbyensis from the Late Triassic of Texas, USA and its implications for early dinosaur evolution. Acta Palaeontologica Polonica 63(1): 129–145.
Langer M 2004. Basal Saurischia. In Weishampel, Dodson and Osmolska. The Dinosauria Second Edition. University of California Press. 861 pp.

https://en.wikipedia.org/wiki/Caseosaurus

Enigmatic Perochelys and a review of soft-shell turtle origins

In short:
Current turtle workers are under the mistaken assumption that Carettochelys (Fig. 1) the tube-nosed soft-shell turtle mimic with a domed hard shell and flippers is the outgroup for soft-shell turtles. That is not supported by the large reptile tree (LRT, 1176 taxa) which nests soft-shell turtles apart from hard-shell turtles, both derived from separate small, horned pareiasaurs like Scerlosaurus and Elginia respectively.

With that in mind,
it’s no wonder that two prior authors don’t know where to nest the Early Cretaceous soft-shell turtle, Perochelys (Figs. 2, 3), as derived or basal in the soft-shell clade. Li et al. 2017 and Brinkman et al. 2017 don’t even mention the basalmost soft-shell turtle, Odontochelys, let alone ancestral  taxa like Scerlosaurus and Arganaceras.

Figure 1. Carettochelys in 3 views from Digimorph.org and used with permission.

Figure 1. Carettochelys in 3 views from Digimorph.org and used with permission.

“Trionychidae plus Carettochelyidae form the clade Trionychia (Gaffney and Meylan, 1988; Meylan, 1988; Meylan and Gaffney, 1989; Shaffer et al., 1997; Joyce et al., 2004; Joyce,
2007).”

FIgure 1. Carettochelys, the pig-nose turtle, is a freshwater form with flippers, like marine turtles, by convergence.

FIgure 2. Carettochelys, the pig-nose turtle, is a freshwater form with flippers, like marine turtles, by convergence.

In the large reptile tree
(LRT, 1176 taxa) where we test as many taxa as possible and let the nodes form where they may, the tube-nosed, dome-shelled fresh water turtle with flippers, Carettochelys, nests with Foxemys in the hard-shell clade as a soft-shell turtle mimic. Only the LRT nests Sclerosaurus, Arganaceras and Odontochelys in the outgroup for soft-shell turtles.

“Molecular studies place this clade at the base of crown group Cryptodira (Shaffer et al., 1997; Krenz et al., 2005; Parham et al., 2006; Shaffer, 2009; Barley et al., 2010; Louren¸co et al., 2012), whereas unconstrained morphological studies support a more derived position nested within Cryptodira (Gaffney and Meylan, 1988; Joyce, 2007; Sterli, 2010; Anquetin, 2011; Sterli et al., 2013).”

Figure 4. The skull of Carettochelys in 5 views. This skull shares some traits with Trionyx, but more with Foxemys.

Figure 3. The skull of Carettochelys in 5 views. This skull of this dome-shell turtle shares some traits with the soft-shell Trionyx, but more with the dome-shell Foxemys. Comnpare to Trionyx in figure 4 and you’ll see why convergence has confused the issue of soft turtle origins. Don’t try to figure out turtle origins by yourself. Let the software do it without bias.

“The phylogenetic relationships among modern soft-shelled turtle species are still controversial, but it is generally accepted that Trionychidae consists of two clades, Cyclanorbinae and Trionychinae, and that Trionychinae includes some well-supported monophyletic clades (Meylan, 1987; Engstrom et al., 2004). The taxonomy and phylogenetic relationships of fossil trionychid species are far more controversial, and very little is known regarding the origin and early radiation of this group (Gardner et al., 1995; Joyce and Lyson, 2010, 2011; Vitek and Danilov, 2010; Vitek, 2012; Danilov and Vitek, 2013; Joyce et al., 2013).”

As I said… see above.

Figure 3. Trionyx, a softshell turtle with bones colorized.

Figure 4. Trionyx, a softshell turtle with bones colorized.

“The early record of soft-shelled turtles is poor, and most taxa are based either on fragmentary shells or skulls (Yeh, 1994; Hutchison, 2000; Sukhanov, 2000; Danilov and Vitek, 2013). More complete Mesozoic skull-shell-associated materials have been described only for trionychids from the Campanian and Maastrichtian of North America (Gardner et al., 1995; Brinkman, 2005; Joyce and Lyson, 2011; Vitek, 2012) or the Cenomanian–Santonian of Mongolia (Danilov et al., 2014). The new material described herein is a nearly complete skeleton and therefore represents the first complete Early Cretaceous skull shell-associated trionychid worldwide.”

Figure 1. Perochelys (Early Cretaceous) in situ

Figure 5. Perochelys (Early Cretaceous) in situ from Li et al. 2015) colors added.

Perochelys lamadongensis (Early Cretaceous)

Figure 2. Perochelys skull in dorsal and ventral views.

Figure 6. Perochelys skull in dorsal and ventral views from Li et al. 2015 with colors added.

Brinkman et al. 2017 looked at another specimen of Perochelys.

Here’s the abstract:
“Pan-trionychids or softshell turtles are a highly specialized and widespread extant group of aquatic taxa with an evolutionary history that goes back to the Early Cretaceous. The earliest pan-trionychids had already fully developed the “classic” softshell turtle morphology and it has been impossible to resolve whether they are stem members of the family or are within the crown. This has hindered our understanding of the evolution of the two basic body plans of crown-trionychids. Thus it remains unclear whether the more heavily ossified shell of the cyclanorbines or the highly reduced trionychine morphotype is the ancestral condition for softshell turtles.”

Softshell turtles never had a heavily ossified shell as demonstrated by Odontochelys and Sclerosaurus, taxa excluded from all prior soft-shell turtle studies.

Figure 7. Trionyx, an African soft-shelled turtle with fossil relatives back to the Cretaceous nests with Odontochelys.

Figure 7. Trionyx, an African soft-shelled turtle with fossil relatives back to the Cretaceous nests with Odontochelys.

“A new pan-trionychid from the Early Cretaceous of Zhejiang, China, Perochelys hengshanensis sp. nov., allows a revision of softshell-turtle phylogeny. Equal character weighting resulted in a topology that is fundamentally inconsistent with molecular divergence date estimates of deeply nested extant species. In contrast, implied weighting retrieved Lower Cretaceous Perochelys spp. and Petrochelys kyrgyzensis as stem trionychids, which is fully consistent with their basal stratigraphic occurrence and an Aptian-Santonian molecular age estimate for crown-trionychids. These results indicate that the primitive morphology for soft-shell turtles is a poorly ossified shell like that of crown-trionychines and that shell re-ossification in cyclanorbines (including re-acquisition of peripheral elements) is secondary.”

That’s what I’ve been trying to tell turtle workers.
And I presented the phylogenetic evidence in Odontochelys and Sclerosaurus. Brinkman et al. do not present these taxa.

Figure 3. Soft shell turtle evolution featuring Arganaceras, Sclerosaurus, Odontochelys and Trionyx.

Figure 8. Soft shell turtle evolution featuring Arganaceras, Sclerosaurus, Odontochelys and Trionyx.

Distinct from soft-shell turtles, hard-shell turtles have:

  1. domed carapace with scutes
  2. dorsal rib tips not visible
  3. premaxilla and maxilla curved one way or another
  4. large quadratojugal, even when fused to the squamosal above it
  5. large premaxilla (forming the ventral margin of the confluent nares
  6. nasal fused to prefrontal
  7. postorbital fused to postfrontal
  8. an ancestry with a broad, bony, convex cranium, which erodes convergent with soft-shell taxa

Like soft-shell turtles, soft-shell turtle mimics with domed hard shells often have:

  1. orbits visible in dorsal view
  2. elongate cervicals
  3. posttemporal fenestra at least half the skull length (but never(?) reaching the jugal)
  4. slender digits
  5. posteriorly elongate supraoccipital with inverted ‘T’ cross-section

Bottom line:
Don’t try to figure out turtle origins by yourself. Let the software do it without bias. 

References
Li L, Joyce WG and Liu J 2015. The first soft-shelled turtle from the Jehol Biota of China. Journal of Vertebrate Paleontology 35(2):e909450. 2015
Brinkman D, Rabi M and Zhao L-J 2017. Lower Cretaceous fossils from China shed light on the ancestral body plan of crown softshell turtles (Trionychidae, Cryptodira). Scientific Reports 2017(7):6719.

Ascendonanus nestleri: an early Permian iguanid, not a varanopid.

Please see:
https://pterosaurheresies.wordpress.com/2018/03/20/the-early-permian-ascendonanus-assemblage/ Which shows that of the five specimens assigned to Ascendonanus at least two are widely divergent. The other three have not yet been tested. One is an iguanid. Another is a basalmost diapsid.

Just out today by Spindler et al. 2018, but previewed earlier
“A new fossil amniote from the Fossil Forest of Chemnitz (Sakmarian-Artinskian transition, Germany) is described as Ascendonanus nestleri gen. et sp. nov., based on five articulated skeletons with integumentary preservation. The slender animals exhibit a generalistic, lizard-like morphology. However, their synapsid temporal fenestration, ventrally ridged centra and enlarged iliac blades indicate a pelycosaur-grade affiliation. Using a renewed data set for certain early amniotes with a similar typology found Ascendonanus to be a basal varanopid synapsid. This is the first evidence of a varanopid from Saxony and the third from Central Europe, as well as the smallest varanopid at all. Its greatly elongated trunk, enlarged autopodia and strongly curved unguals, along with taphonomical observations, imply an arboreal lifestyle in a dense forest habitat until the whole ecosystem was buried under volcanic deposits. Ascendonanus greatly increases the knowledge on rare basal varanopids; it also reveals a so far unexpected ecotype of early synapsids. Its integumentary structures present the first detailed and soft tissue skin preservation of any Paleozoic synapsid.”

Except
Ascendonanus is not a varanopid synapsid. It’s an arboreal lepidosaur, an iguanid squamate in the large reptile tree (LRT, 1176 taxa, subset Fig. 3) with a typical skull, skin, size and niche typical for this clade. Only the torso has more vertebrae than is typical, but the related Liushusaurus also has more than 25 presacral vertebrae.

The Early Permian
is not where we expect to see lizards. No others are known from this period. Perhaps that is why Spindler et al. 2018 chose to restrict their taxon list to synapsids and their outgroups…and to ignore those upper temporal fenestrae, so plainly visible (Fig. 1). And note those slender, vertical epipterygoids. You don’t see those on synapsids.

Figure 1. The skull of Ascendonanus has a diapsid temporal configuration with clearly visible upper temporal fenestra and a typical iguanid skull morphology.

Figure 1. The skull of Ascendonanus has a diapsid temporal configuration with clearly visible upper temporal fenestra and a typical iguanid skull morphology. Note manual digit 5 preserved beneath the palm of the hand and restored to a lateral position. Not also the two jugal ascending processes, due to the split leaving medial and lateral halves of this bone. Note the two slender epipterygoids inside the temporal openings. Only squamates have such bones.

Ascendonanus nestleri (Spindler 2017, TA1045) is a German iguanid squamate found in vulcanized early Permian (291mya) sediments. It is the oldest lepidosaur known and based on its phylogeny, suggests an earlier radiation of lepidosaurs that earlier presumed. Other early lepidosauriformes include Paliguana and Lacertulus from the Late Permian. Other basal iguanids and pre-iguanids, like Scandensia, Calanguban, Euposaurus and Liushusaurus are late-survivors in the Late Jurassic and Early Cretaceous. Iguana is a late-survivor of an early radiation living today.

Ascendonanus was originally described
as a tree-climbing varanopid synapsid by Spindler et al. (2018), but no lepidosauriformes were tested. The bones are difficult to see through the scaly skin (Fig. 1). Upper temporal fenestra and other lepidosaur traits were overlooked, perhaps because lizards are otherwise unknown from the Early Permian. No other basal synapsids were arboreal, but some Iguana species are also arboreal. No other varanopids are quite as small, but other iguanids are smaller.

By the way, like more paleo workers
Spindler et al. 2018 were unaware of the synapsid/prodiapsid split that removes many former varanopids from the clade Synapsida, despite their having typical synapsid temporal fenestration. One more reason NOT to label taxa based on traits, but to only label taxa after a wide gamut cladistic analysis, like the LRT.

Thus
we no longer call Ascendonanus a diapsid based on its diapsid temporal configuration. True diapsids, like Eudibamus and Petrolacosaurus, all nest within the Archosauromorpha. By convergence, all members of the clade Lepidosauriformes, including Ascendonanus, all have a diapsid temporal configuration or a modification based on that.

Figure 1. Ascendonanus nestler is an Early Permian lepidosaur nesting with Saniwa, a member of the Varanoidea.

Figure 2. Ascendonanus nestler is an Early Permian iguanid squamate lepidosaur, not a varanopid synapsid.

Sorry to say it,
taxon exclusion is once again the problem here. Spindler et al. 2018 were also following tradition when they included caseids and eothyrids in they analysis of synapsids. The Caseasauria nest elsewhere when given the opportunity to do so.

Figure 3. Ascendonanus cladogram, subset of the LRT. Here Ascendonanus nests with iguanids, not varanopids.

Figure 3. Ascendonanus cladogram, subset of the LRT. Here Ascendonanus nests with iguanids, not varanopids.

Figure 5. Ascendonanus pes.

Figure 5. Ascendonanus pes.

References
Rößler R, Zierold T, Feng Z, Kretzschmar R, Merbitz M, Annacker V and Schneider JW 2012. A snapshot of an early Permian ecosystem preserved by explosive volcanism:
New results from the Chemnitz Petrified Forest, Germany. PALAIOS, 2012, v. 27, p. 814–834.
Spindler F, Werneburg R, Schneider JW, Luthardt L, Annacker V and Räler R 2018. First arboreal ‘pelycosaurs’ (Synapsida: Varanopidae) from the early Permian Chemnitz Fossil Lagerstätte, SE Germany, with a review of varanopid phylogeny. DOI: https://doi.org/10.1007/s12542-018-0405-9

Agadirichnus elegans pterosaur tracks rediscovered

Yesterday we looked at a recent online paper that expanded the list of pterosaur taxa present at the last days of pterosaurs and dinosaurs in the latest Cretaceous. Absent from that highly publicized work were the Maastrichtian pterosaur tracks made by ctenochasmatids (some quite large) listed below and the tupuxuarid skull described earlier.

Masrour et al. 2018
rediscover Maastrichtian (Late Cretaceous) dinosaurs, birds and enigmatic 8-9 cm pes tracks and 6cm manus tracks tentatively attributed to some sort of ‘Lacertilia’ under the name Agadirichnus elegans, first documented in Ambroggi and Lapparent 1954. The originals are now considered lost. The site in Morrocco was rediscovered. The enigma tracks were retrospectively identified as two pterosaur morphotypes.

Unknowingly,
these were the first pterosaur tracks ever named, preceding Pteraichnus by three years.

Etymology:
named after Agadir, the Moroccan city near the site.

Biggest takeaway:
There was a variety of pterosaurs in the Maastrichtian (Latest Cretaceous) that is presently underrepresented by skeletons (currently just giant azhdarchids and pteranodontids in rare fossiliferous strata worldwide).

Figure 1. A variety of tracks inappropriately labeled Agadirichnus. Here one pedal track is matched to Middle Jurassic Darwinopterus, perhaps by convergence. But maybe not.

Figure 1. A variety of tracks inappropriately labeled Agadirichnus. Here only one pedal track (B) is matched to Middle Jurassic Darwinopterus, perhaps by convergence. Note what appears to be pedal digit 5 beneath the heel.

The catalog of pterosaur pedes
(Peters 2011) was not cited, but I’ll use it to attempt a trackmaker identification.

A Pteranodon pes, UNSM 2062

Figure 1. A Pteranodon pes, UNSM 2062 as reconstructed plantigrade by Bennett (1991, 2001) and as reconstructed digitigrade. PILs added. Black elements are foreshortened during elevation into the digitigrade configuration. Some Pteranodon pedes were indeed plantigrade, depending on the species, but not this one based on PILs analysis. Note the distal and proximal tarsals are fused to each other.

Taxon B with pedal digit 3 the longest matches:

  1. Dimorphodon
  2. Darwinopterus (certain specimens only)
  3. Wukongopterus
  4. Ctenochasma elegans
  5. Pterodaustro
  6. Shenzhoupterus
  7. Pteranodon UNSM 2062 specimen only

Taxon B with digit 1 no longer than p2.2 matches

  1. Darwinopterus
  2. Wukongopterus
  3. Ctenochasma elegans
  4. Pterodaustro 
  5. Pteranodon UNSM 2062 specimen only

Taxon B with p4 subequal to mt 4 matches

  1. Pteranodon UNSM 2062 specimen only. Other tested Pteranodon specimens do not extend digit 3 beyond the others, as shown here. The only problem is: the fingers of Pteranodon cannot touch the substrate due to the long metacarpus relative to the short hind limbs. My guess: there was a large, as yet unknown, ctenochasmatid trackmaker in the Late Cretaceous. Ctenochasmatids had a short manual digit 1 and small dull claws on all digits matching the manus impression of Taxon A. Perhaps this was one of the giant ctenochasmatids, like Gegepterus, at present lacking data for both feet and fingers.

Taxon C with pedal digit 2 the longest, toes shorter than metatarsals and a narrow pes matches:

  1. Zhejiangopterus (probaby juvenile based on 6cm size)

Taxon D with pedal digit 2=3, toes shorter than metatarsals and metatarsal 4 much shorter than 1-3 matches:

  1. Ctenochasma

References
Ambroggi R and de Lapparent  AF 1954. Les empreintes de pas fossiles du Maestrichtien d’Agadir. Notes du Service Geologique du Maroc, 10:43–6.
Longrich NR, Martill DM, Andres B 2018. Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biol 16(3): e2001663. https://doi.org/10.1371/journal. pbio.2001663
Masrour M, Ducla M d, Billon-Bruyat J-P and Mazin J-M 2018. Rediscovery of the Tagragra Tracksite (Maastrichtian, Agadir, Morocco): Agadirichnus elegans Ambroggi and Lapparent 1954 is Pterosaurian Ichnotaxon, Ichnos.  https://doi.org/10.1080/10420940.2017.1386661