Sookias et al. 2020: Euparkeria updated, cladogram outdated

Cutting to the chase: 
No one has studied and published on Euparkeria (Figs. 3-6) more than Roland Sookias and his colleagues (Sookias et al.  2014, Sookias 2016, Sookias et al. 2020). Unfortunately taxon exclusion mars all of his work (Figs. 1, 2), including his latest, otherwise terrific paper presenting close-up and µCT scans from the ten specimens found in a single locality, all attributed to Euparkeria. This paper is so rich in data, but so poor and misleading in systematics.

From the abstract:
“The archosauriform Euparkeria capensis from the Middle Triassic (Anisian) of South Africa has been of great interest since its initial description in 1913, because its anatomy shed light on the origins and early evolution of crown Archosauria and potentially approached that of the archosaur common ancestor.”

In the large reptile tree (LRT, 1714+ taxa, subset Fig. 1) Euparkeria nests far from Archosauria (= the last common ancestor of birds + crocs). Instead Euparkeria nests at the base of the Euarchosauriformes (= all archosauriforms closer to Euparkeria than to Proterosuchus and the pararchosauriforms, Fig. 1). These clades were separated in 2012 here, and that split has remained steady despite many additional taxa.

Figure 1. Subset of the LRT focusing on Archosauriformes. Clade colors match figure 2 overlay.

Phylogenetic analysis
Sookias et al. 2020 worked from a dataset in Sookias 2016. Sookias 2016 was built on the invalidated Nesbitt 2011 and Sookias et al. 2014. The Sookias et al. 2020 results are typical whenever taxon exclusion shuffles the clades, mixing unrelated taxa together. Clades nest where they do in Sookias 2020 by default. That’s how you get crocs and phytosaurs nesting together and euparkeriids arising from erythrosuchids (Fig. 2), rather that the other way around, as in the LRT (Fig. 1). We’re also wary of any cladogram that includes suprageneric taxa.

Figure 2. Sookias et al. 2020 cladogram lacks enough taxa compared to the LRT (Fig. 2) and so shuffles clades here. Here crocs nest within ‘Other Pseudosuchia’ and pterosaurs nest within Ornithodira, two clades invalidated by the LRT by adding taxa. Promoting this outdated myth of interrelationships in 2020 is not professional. Dongusuchus and Dorosuchus are know from bits and pieces of the post-crania.

Euparkeria has been studied previously,
but never so completely as in Sookias et al. 2020. As in Ewer (1965, Fig. 3) Sookias et al. present a freehand diagram chimaera skull (Figs. 4, 5) that combines data from several specimens they consider to be conspecific.

Figure 3. Previous views of Euparkeria.

Comparing a photo of the SAM 5867 specimen
to the Sookias et al. diagram may be instructive. Did they get all the details right?

Figure 4. How does the skull of the 5867 specimen of Euparkeria compare to the diagram? Here they are to the same scale. You decide on the details.

Several color photos were included in Sookias et al. 2020,
so it is surprising that their diagram lacks colors (Fig. 5 left column). When colors are added, the bones lump and separate as well as the LRT lumps and separates taxa.

Figure 5. Diagram from Sookias et al.  2020 at left. Rearranged and colored at right for ease of viewing.

Using a little DGS on a skull tracing of the SAM 4067a specimen
(Fig. 6) permits one to copy and paste elements from the left and right to create a reconstruction (Fig. 6) without reverting to the unconscious bias that attends all freehand drawings. Broom 1913 assigned this specimen to Browniella africana. Haughton 1922 considered Browniella a junior synonym and this synonymy has been accepted by all prior workers. No prior workers provided a reconstruction for accurate scoring. They just  ‘eye-balled’ the roadkill skull.

Figure 6. Browniella africana, the SAM 4967a specimen attributed to Euparkeria. Images from Sookias et al. 2020 with colors and reconstruction added here.

Euparkeria capensis (Broom 1913, SAM 5867) Early Triassic, ~247 mya, 60 centimeter length is derived from the FMNH UC 1528 specimen of Youngoides (Fig. 7), a taxon ignored by Sookias et al. An unpublished paper can be found on ResearchGate.net.

The SAM 5867 specimen of Euparkeria nests between Pararchosauriformes, like Polymorphodon (Fig. 8), and all higher Euarchosauriformes like Garjainia (Fig. 9). The SAM 5867 specimen nests at the base of the Euparkeriidae, which presently include only two other tax, the SAM 4067a specimen (Fig. 6) and Osmolskina, which nest with each other (Fig. 1).

Figure 7. Youngoides romeri FMNH UC1528 demonstrates an early appearance of the antorbital fenestra in the Archosauriformes. This specimen is the outgroup to the Archosauriformes.

Figure 8. Skull elements of Polymorphodon, basal to proterochampsids.

Figure 9. Garjainia at several scales and views.

Osmolskina czatkowicensis (Borsuk-Biaynicka and Evans 2009), Early Triassic,

Browniella africana  (Fig. 6, SAM 4067A) is a eurparkeriid more closely related to Osmolskina in the LRT.

Sometimes additional detail comes in handy.
And Sookias et al.  2020 provided that additional detail.

Unfortunately, without a valid phylogenetic context
you won’t know the outgroups, ingroups, ancestors and descendants of any taxon under your µCT scanner. Sometimes you need a metaphorical ‘panoramic camera’ like the LRT, for that wide gamut view that minimizes taxon exclusion.

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References
Broom R 1913. On the South-African Pseudosuchian Euparkeria and Allied Genera. Proceedings of the Zoological Society of London 83: 619–633.
Borsuk-Bialynicka M and Evans SE 2009. Cranial and mandibular osteology of the Early Triassic archosauriform Osmolskina czatkowicensis from Poland. Palaeontologia Polonica 65, 235–281.
Ewer RF 1965. The Anatomy of the Thecodont Reptile Euparkeria capensis Broom Philosophical Transactions of the Royal Society London B 248 379-435.
doi: 10.1098/rstb.1965.0003
Haughton S 1922. On the reptilian genera Euparkeria Broom, and Mesosuchus Watson. Transactions of the Royal Society South Africa 10, 81–88. (doi:10.1080/00359192209519270
Nesbitt SJ 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bull. Am. Mus. Nat. Hist. 352, 1–292. (doi:10.1206/352.1)
Nesbitt SJ et al. 2017 The earliest bird-line archosaurs and the assembly of the dinosaur body plan. Nature 544, 484–487.
Sookias RB, Sullivan C, Liu J, Butler RJ. 2014 Systematics of putative euparkeriids (Diapsida: Archosauriformes) from the Triassic of China. PeerJ2, e658 (doi:10.7717/peerj.658)
Sookias RB 2016. The relationships of the Euparkeriidae and the rise of Archosauria. Royal Soceity open science 3, 150674. (doi:10.1098/rsos. 150674)
Sookias RB, Dilkes D, Sobral G, Smith RMH, Wolvaardt FP, Arcucci AB, Bhullar B-AS and Werneburg I 2020. The craniomandibular anatomy of the early archosauriform Euparkeria capensis and the dawn of the archosaur skull. R. Soc. Open Sci. 7: 200116.
http://dx.doi.org/10.1098/rsos.200116

https://www.researchgate.net/publication/328388486_Youngoides_romeri_and_the_origin_of_the_Archosauriformes

wiki/Osmolskina
http://reptileevolution.com/euparkeria.htm
http://reptileevolution.com/osmolskina.htm

What is Polymorphodon adorfi?

Sues et al. 2020 bring us a new Middle Triassic German diapsid,
Polymorphodon adorfi (Fig. 1; SMNS 91343, SMNS 91400) with a large toothy premaxilla and a hint of an antorbital fenestra.

Figure 1. Skull elements of Polymorphodon. Consider the possibility that the quadrate had an anterior lean, as in figure 2,, elongating the postorbital region of the skull.

At first glance Polymorphodon looks a lot like
Archosaurus (Fig. 2; Late Permian, eastern Europe), a taxon not yet tested in the LRT due to a paucity of material.

Figure 2. Archosaurus is not in the LRT, but shares several traits with Polymorphodon.

From the Sues et al. abstract
“Skeletal remains of a small reptile with a distinctive dentition from the Lower Keuper (Erfurt Formation; Middle Triassic, Ladinian) of the Schumann quarry near Eschenau, in the municipality of Vellberg in Baden-WÃrttemberg, Germany, represent a new taxon of non-archosaurian archosauriforms, Polymorphodon adorfi.”

That’s a wee bit general. Let’s see if the large reptile tree (LRT, 1698+ taxa; subset Fig. 5) can nest it more precisely.

The Sues et al. abstract continues:
“It is diagnosed by various craniodental autapomorphies, including mesial and distal carinae of labiolingually flattened maxillary and dentary tooth crowns with large, somewhat hook-shaped denticles aligned at distinct angle to apicobasal axis of tooth crown; premaxilla with long, leaf-shaped posterodorsal process that is slightly longer than body of element; presence of prominent lateral fossa on premaxilla anteroventral to external narial fenestra; premaxilla with five gently recurved, conical teeth; medial surface of maxilla with distinct ledge above the interdental plates; and maxilla and dentary with distinctly heterodont dentition”

The Sues et al. diagnosis is focusing on the dentition, plus the premaxilla and maxilla. Again, not much to work with, even though quite distinctive.

The Sues et al. abstract continues:
“Phylogenetic analysis recovered Polymorphodon adorfi in a position crownward of Erythrosuchus africanus but in an unresolved polytomy with derived non-archosaurian archosauriforms such as Proterochampsidae and Euparkeria capensis and with Archosauria.”

The first red flag: Proterochampsidae is not related to Euparkeria in the LRT. Simply add taxa to fix this.

The Sues et al. abstract continues:
“The maxillary and dentary teeth of Polymorphodon adorfi differ from those of other non-archosaurian archosauriforms and indicate a different, possibly omnivorous diet, suggesting that these reptiles were more diverse in terms of feeding habits than previously assumed.”

This abstract plus Wikipedia information plus results from the LRT indicate taxon exclusion is the issue here.

In the LRT (subset Fig. 5, not yet updated)
Polymorphodon nests at the base of the Pararchosauriformes, basal to all the many included proterosuchids, choristoderes, phytosaurs and proterochampsids in that order (Fig. 5). In the LRT the clade Pararchosauriformes is a sister to the clade Euarchosauriformes, which begins with two specimens of Euparkeria and ends with crocs, dinos and birds. All these are derived from the UC 1528 specimen of Youngoiides (Fig. 3), the most derived of the various non-archosauriform younginids.

Figure 3. Cladogram on the Polymorphodon Wikipedia page based on Ezcurra 2016. Note the lack of taxa preceding the taxon “Proterosuchidae”, which is where the LRT nests Polymorphodon.

So, yes, taxon exclusion is the problem
with the Sues et al. 2020 cladogram based on the Ezcurra 2016 cladogram, which suffered from taxon exclusion, as detailed here four years ago.

Polymorphodon is a late survivor
of a Late Permian radiation and is a key taxon with many pararchosauriform descendants. This hypothesis of relationships was overlooked by the original authors due to taxon exclusion.

Figure 4. Updated image of various proterosuchids and their kin within the LRT clade, Pararchosauriformes. When you see them all together it is easier to appreciate the similarities and slight differences that are gradual accumulations in derived taxa.

I still have not seen the Sues et al. 2020 PDF.
When it arrives (see below) we’ll see if it includes Youngoides, Archosaurus and many of the pertinent taxa in figure 4. Since they are using Ezcurra 2016 the odds are reduced. For now the nesting of Polymorphodon in the LRT is more certain and more stem-ward than originally proposed (Fig. 3).

Figure 5. Cladogram of basal archosauriforms from 2016. Polymorphodon nests basal to Proterosuchus BPI 1 4016, awaiting an update soon.

Adding taxa solves so many problems.
Not sure why academics are hesitating to do what needs to be done. Sure it’s hard work, but it only has to be done once.

Via email
Hans Sues indicated that a PDF of the paper will be ready within a week due to some publisher issues linking the supplemental information. We may explore this taxon again if that data provides information not available from present sources. For now, only a little data from a new taxon was enough to nest it with confidence, so long as taxon exclusion is minimized, as it is in the LRT. This helpful online resource is free for all to use.

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References
Sues H-D, Schoch RR, Sobral G and Irmis RB 2020. A new archosauriform reptile with distinctive teeth from the Middle Triassic (Ladinian) of Germany. Journal of Vertebrate Paleontology Article: e1764968 (advance online publication)
doi: https://doi.org/10.1080/02724634.2020.1764968
https://www.tandfonline.com/doi/abs/10.1080/02724634.2020.1764968Â

wiki/Polymorphodon

Rugarhynchos: Late Triassic archosauriform really close to Doswellia

A former Doswellia sp.
(Heckert et al. 2012) has be reexamined and renamed Rugarhynchos sixmilensis by Wynd et al. 2020.

The resemblance is remarkable
(Fig. 1) and the size is similar. Both are from the Late Triassic of North America (Virginia and New Mexico). Wynd et al. did a good job of tracing the bones, but provided no reconstructions (they pictured the premaxilla on a separate page spread). They also misidentified the surangular (SA) as the quadratojugal.

Is this just another species of Doswellia?
We’ve seen more variation in Rhamphorhynchus, and Pteranodon, but naming a new genus is reserved for full professors and their students. In this case, the resemblance is readily apparent, and so are the various enlargements and reductions. The problem lies, as it often does, in the published cladogram (Fig. 2) suffering from taxon exclusion.

Figure 1. Doswellia skull compared to Rugarhynchos, here reduced to a similar length for rapid comparison.

From the abstract:
“Stem archosaurs exhibit substantial cranial disparity, especially by taxa either shortening or elongating the skull. This disparity is exemplified in the North American Late Triassic proterochampsians by the âshort-facedâ Vancleavea and the ong-faced doswelliids.”

When more taxa are added, as in the large reptile tree (LRT, 1695+ taxa; subset Fig. 3), Vancleavea nests with Helveticosaurus in the Thalattosauria, as we learned several years ago. Missing from the Wynd et al. taxon list are any choristoderes. Those are close relatives to doswellids in the LRT.

“To critically investigate skull elongation and character evolution in these proterochampsians, we evaluate Doswellia sixmilensis, known from much of a skull, cervical centra, and osteoderms from the Bluewater Creek Member of the Chinle Formation of New Mexico.” (See Fig. 1).

Figure 2. Cladogram from Wynd et al. 2020 with colors added to show where these taxa nest when more taxa are added, as in the LRT. Avemetatarsalia is invalid because it includes both pterosaurs and dinosaurs, neither of which is related to Vancleavea or Phytosauria in the LRT. Remember to check your results for mismatches like this.

From the abstract:
“Rugarhynchos sixmilensis, gen. et comb. nov., exhibits an elongate snout with characteristics known in stem and crown archosaurs, including a downturned premaxilla and fluted teeth.”

In the LRT, archosaurs include only crocs + dinos (including birds). Due to taxon exclusion (chiefly bipedal basal crocodylomorphs) Wynd et al. expand that list to include many other taxa.

“We included R. sixmilensis in a phylogenetic analysis of archosauromorphs consisting of 677 characters and 109 taxa under both parsimony and Bayesian models.”

Now do you see why increasing the number of taxa is MUCH more important than increasing the number of characters? How one taxon relates to other taxa requires a lot of other taxa… and a sufficient number to traits (150+). The LRT includes 238 multi-state taxa and it nests everything from fish to humans with high resolution.

“We recover R. sixmilensis as a doswelliid, sister to Doswellia kaltenbachi. Our parsimony and Bayesian models differ in the placement of Doswelliidae, either as sister to or within Proterochampsidae, respectively.”

Wynd et al. excluded too many pertinent taxa. Here’s where the LRT (Fig.3) nests Doswellia and the pararchosauriformes.

“We use archosauromorph relationships from the Bayesian model to estimate cranial disparity between stem and crown archosaurs and find a narrow breadth of morphological disparity in the stem. Our results suggest that crown archosaurs evolved disparate crania from a low-disparate archosauriform condition.”

Without a valid phylogenetic context (Fig. 3), the results of Wynd et al. cannot be validated. They need more taxa.

Figure 3. Subset of the large reptile tree focusing on the pararchosauriformes and the Choristodera, still similar since 2015. Euparkeria is basal to the Euarchosauriformes, including Archosauria.

The skull of Rugarhynchos was added to a graphic
(Fig. 4) that included Doswellia and its relatives to scale. Many of these taxa were omitted from Wynd et al. 2020.

Figure 4. Updated image of various proterosuchids and their kin. When you see them all together it is easier to appreciated the similarities and slight differences that are gradual accumulations of derived taxa.

Wynd et al. considered Rugarhynchos a proterochampsid.
With more taxa added (Figs. 3, 4) that’s not confirmed by the LRT. Doswellia is slightly closer to choristoderes, a clade not shown in the Wynd et al. cladogram (Fig. 2). It would have been better if Wynd et al also added a variety of proterosuchids, as in the LRT. They are all as different and distinct as Rugarhynchos is from Doswellia.

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References
Wynd BM, Nesbitt SJ, Stocker MR and Heckert AB 2020. A detailed description of Rugarhynchos sixmilensis, gen. et comb. nov. (Archosauriformes, Proterochampsia), and cranial convergence in snout elongation across stem and crown archosaurs. Journal of Vertebrate Paleontology Article: e1748042
doi: https://doi.org/10.1080/02724634.2019.1748042
https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1748042

Megaevolutionary dynamics in reptiles: Simoes et al. 2020

Simoes et al 2020 discuss
“rates of phenotypic evolution and disparity across broad scales of time to understand the evolutionary dynamics behind the origin of major clades, or how they relate to rates of molecular evolution.”

“Here, we provide a total evidence approach to this problem using the largest available data set on diapsid reptiles.”

Unfortunately not large enough to understand that traditional ‘diapsid’ reptiles are diphyletic, splitting in the Viséan and convergently developing two

“We find a strong decoupling between phenotypic and molecular rates of evolution,”

Yet another case of gene-trait mismatch in analysis.

“and that the origin of snakes is marked by exceptionally high evolutionary rates.”

Taxon exclusion is the reason for this exclusion.

Figure 1. Cladogram from Simoes et al. 2020. Gray tones added to show Lepidosauromorpha in the LRT.

“Here, we explore megaevolutionary dynamics on phenotypic and molecular evolution during two fundamental periods of reptile evolution: i) the origin and early diversification of the major lineages of diapsid reptiles (lizards, snakes, tuataras, turtles, archosaurs, marine reptiles, among others) during the Permian and Triassic periods,”

In the LRT the new archosauromorphs split from new lepidosauromorphs in the Viséan (Early Carboniferous).

“as the origin and evolution of lepidosaurs (lizards, snakes and tuataras) from the Jurassic to the present.”

In the LRT lepidosaurs had their origin in the Permian and the Simoes team ignores the Triassic radiation of lepidosaurs leading to tanystropheids and pterosaurs.

So without a proper and valid phylogenetic context,
why continue? How can they possibly discuss ‘rates of change’ if they do not include basal taxa from earlier period?

“Our results indicating exceptionally high phenotypic evolutionary rates at the origin of snakes further suggest that snakes not only possess a distinctive morphology within reptiles,  but also that the first steps towards the acquisition of the snake body plan was extremely fast.”

In the LRT many taxa are included in the origin of snakes from basal geckos. These are missing from Simoes list of snake ancestor.

Figure 1.  Subset of the LRT focusing on lepidosaurs and snakes are among the squamates.

In the LRT all sister taxa resemble one another
and document a gradual accumulation of derived traits.

If you have any particular evolutionary questions,
they were probably answered earlier in previous posts. Use the keyword box at upper right to seek your answer.

 

Erpetosuchus now nests outside of the Archosauria + Poposauria in the LRT

Based on its uniquely inset tooth row
(Figs. 1–3) Erpetosuchus (Newton 1894; Late Carnian, Late Triassic) has been a traditional enigma taxon.

Figure 1. Erpetosuchus in several views. Here the post-crania of Parringtonia is added.

According to Wikipedia,
“The relationship of Erpetosuchus to other archosaurs is uncertain. In 2000 and 2002, it was considered a close relative of the group Crocodylomorpha, which includes living crocodylians and many extinct relatives. However, this relationship was questioned in a 2012 analysis that found the phylogenetic placement of Erpetosuchus to be very uncertain.”

“Benton and Walker (2002) found the same sister-group relationship and proposed the name Bathyotica for the clade containing Erpetosuchus and Crocodylomorpha.”

“Nesbitt and Butler (2012) included Erpetosuchus within a more comprehensive phylogenetic analysis and found it to group with the archosaur Parringtonia (Fig. 1) from the Middle Triassic of Tanzania. Both were part of the clade Erpetosuchidae. Nesbitt and Butler did not find support for the sister-group relationship between Erpetosuchus and Crocodylomorpha. Instead, erpetosuchids formed a polytomy or unresolved evolutionary relationship at the base of Archosauria along with several other groups. It could take many positions within Archosauria, but none were as a sister taxon of Crocodylomorpha.”

Figure 2. Erpetosuchus, Tarjadia, Parringtonia now nest with Decurisuchus outside of the Archosauria + Poposauria. Note the extreme anterior lean of the quadrate and quadratojugal here, convergent with crocodyliformes.

A recent review of the Crocodylomorpha
subset of the large reptile tree (LRT, 1660+ taxa; Fig. 4) knocked Erpetosuchus out of the Crocodylomorpha and out of the Archosauria. Erpetosuchus and other members assigned to the Erpetosuchidae (Pagosvenator, Parringtonia, Tarjadia (Figs. 2-3), but not the basal marine crocodile Dyoplax, at least not yet) now nest with Decuriasuchus (Figs. 2–3) in the LRT. This clade nests between Rauisuchia and Poposauria + Archosauria (Fig. 4).

Figure 3. Erpetosuchus and kin illustrated to scale. Parringtonia + Tarjadia + Erpetosuchus now nest with Decuriasuchus basal to Poposaurs + Archosauria.

The small size of Erpetosuchus
(Fig. 3) is a derived trait, following several much larger ancestors. Alas, as far as we know, Erpetosuchus was a terminal taxon, leaving no descendants.

Figure 4. Subset of the LRT focusing on the Crocodylomorpha, dorsal scutes, elongate proximal carpals, bipedality and clades.

Why was Erpetosuchus traditionally considered ‘crocodile-like’?
The extreme anterior lean of the quadrate and quadratojugal are typical crocodile traits shared by convergence with members of the clade Erpetosuchidae (including Decuriasuchus).

Eagle-eyed readers may note
a few other changes in the Crocodylomorpha subset of the LRT (Fig. 4). We’ll deal with these in future blogposts.

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References
Benton MJ and Walker AD 2002. Erpetosuchus, a crocodile-like basal archosaur from the Late Triassic of Elgin, Scotland, Zoological Journal of the Linnean Society 136:25-47.
Nesbitt SJ and Butler RJ 2012. Redescription of the archosaur Parringtonia gracilis from the Middle Triassic Manda beds of Tanzania, and the antiquity of Erpetosuchidae. Geological Magazine: 1. doi:10.1017/S0016756812000362
Nesbitt SJ, Stocker MR, Parke WGr, Wood TA, Sidor CA and Angielczy KD 2018. The braincase and endocast of Parringtonia gracilis, a Middle Triassic suchian (Archosaur: Pseudosuchia) Journal of Vertebrate Paleontology 37, Memoir 17: Vertebrate and Climatic Evolution in the Triassic Rift Basins of Tanzania and Zambia.
Newton TE 1894. Reptiles from the Elgin Sandstone—Description of two new genera. Philosophical Transactions of the Royal Society of London, B, 185:573–607.

wiki/Tarjadia
wiki/Parringtonia
wiki/Erpetosuchus

http://reptileevolution.com/decuriasuchus.htm

Is ‘Vjushkovia triplocosta’ a jr synonym for Garjainia prima?

In other words,
are the two erythrosuchid holotypes (Fig. 1) sufficiently alike to be congeneric or conspecific? Garjainia was published first.

Butler et al. 2019 reported
“Two species of Garjainia have been reported from Russia: the type species, Garjainia prima Ochev, 1958, and ‘Vjushkovia triplicostata’ von Huene, 1960, which has been referred to Garjainia as either congeneric (Garjainia triplicostata) or conspecific (G. prima).”

“…little work has been conducted on type or referred material attributed to ‘V. triplicostata’. However, this material includes well-preserved fossils representing all parts of the skeleton and comprises seven individuals. Here, we provide a comprehensive description and review of the cranial anatomy of material attributed to ‘V. triplicostata’, and draw comparisons with G. prima. We conclude that the two Russian taxa are indeed conspecific, and that minor differences between them result from a combination of preservation or intraspecific variation.”

Figure 1. Vjushkova holotype compared to Garjainia. These two nest together in the LRT, but not by much. Several areas, including the antorbital and lateral temporal regions differ greatly. The dorsal view of both are quite distinct, overlooked by Butler et al. 

Combining elements from seven specimens
bears some risk of creating a chimaera. Since Butler et al. felt confident in doing so, and there is no alternative, then I do, too. Given the data presented by Butler et al. I reconstructed the skull from separate elements (Fig. 1), something Butler et al. did not do.

Although the two skulls are extremely similar
and the two taxa nest together in the large reptile tree (LRT, 1602 taxa) a few traits seem to distinguish these two taxa apart from one another, at least at the species level and perhaps at the generic level. Note the larger antorbital fenestra in Vjushkovia. Note the pinched upper portion of the lateral temporal fenestra. Note the concave posterior maxilla. Note the taller, narrower orbit. Note the much more robust quadratojugal and quadrate. Note the greater arch of the posterior postorbital. Note the posterior process of the squamosal. These differences appear to support the separation of these taxa at the generic level, IMHO. The lack of a reconstruction in Butler et al. 2019 may have hampered their decision in this case. The lack of graphic comparison in the paper (no images of the Garjainia holotype are shown side-by-side with those of Vjushkoiva) is also regrettable.

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References
Butler RJ, Sennikov AG, Dunne EM, Ezcurra MD, Hedrick BP, Maidment SCR, Meade LE, Raven TJ and Gower DJ 2019. Cranial anatomy and taxonomy of the erythrosuchid archosauriform ‘Vjushkovia triplicostata’ Huene, 1960, from the Early Triassic of European Russia. Royal Society Open Science 6: 191289. http://dx.doi.org/10.1098/rsos.191289

Criticisms of other papers by Butler as co-author:

https://pterosaurheresies.wordpress.com/2018/06/25/the-rise-of-the-ruling-reptiles-ezcurra-and-butler-2018-fiasco/

https://pterosaurheresies.wordpress.com/2019/10/21/teyujagua-paradoxa-still-no-paradox-in-the-lrt/

https://pterosaurheresies.wordpress.com/2019/04/05/mythbusting-prorotodactylus/

https://pterosaurheresies.wordpress.com/2019/02/06/what-is-gracilisuchus-add-more-taxa-to-find-out/

https://pterosaurheresies.wordpress.com/2018/12/12/ezcurra-et-al-2018-review-garjainia/

Hemiprotosuchus: closer to Aetosaurus than Protosuchus

Not much written about this genus
According to Wikipedia, “Hemiprotosuchus is an extinct genus of protosuchid from the Late Triassic (Norian stage) Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina, South America.” 

Figure 1. Hemiprotosuchus leali skull from Desojo and Ezcurra, nests with Decuriasuchus in the LRT. The variation within this clade is increased with this nesting.

The specimen
(Fig. 1, image from Desojo and Ezcurra 2016) seems to be preserved as a half skull, nearly complete. Bonaparte 1969 first considered this a protosuchid like Protosuchus (Fig. 2), likely due to its low triangular rostrum and high temporal region.

Figure 2. Protosuchus skull. The high cranium and low triangular rostrum evidently made Bonaparte 1969 consider Hemiprotosuchus similar enough to Protosuchus.

After testing
in the large reptile tree (LRT, 1594 taxa) Hemiprotosuchus (PVL 3829, Bonaparte 1969; Norian, Late Triassic) nested between Ticinosuchus (Fig. 3) and aetosaurs, like Stagonolepis and Aetosaurus (Fig. 3).  That’s a long way from Protosuchus in the LRT.

In 1969 no one knew
that Ticinosuchus was basal to aetosaurs. The LRT recovered that relationship here in 2011.

Figure 3. Hemiprotosuhus image from Desojo and Ezccura 2016. Colors added. This taxon is derived from Ticinosuchus, basal to aetosaurs.

Others (e.g. Nesbitt 2011 and works based on that cladogram)
considered Revueltosaurus (Fig. 3) a basal aetosaur. The LRT nests Revueltosaurus closer to the genesis of the Euarchosauriformes (between Euparkeria and Erythrosuchus among lesser known taxa).

Desojo and Ezcurra 2016
accepted the protorosuchian affinities of Hemiprotosuchus without further comment.

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References
Bonaparte JF 1969. Dos nuevas ‘faunas’ de reptiles triasicos de Argentina. Gondwana Stratigraphy (IUGS Symposium, Buenos Aires)2:283–306.
Desojo JB and Ezcurra MD 2016. Triassic pseudosuchian archosaurs of South America. Historia Evolutiva y Paleobiogeográfica de los Vertebratos de América del Sur. XXX Jornados Argentinas de Paleontología de Vertebrados. Contribuciones del MACN No. 6: 57–66.

wiki/Hemiprotosuchus

The skull of PVL 4597 joins its post-crania in the LRT

The PhD thesis of Agustina Lecuona 2013
on the several specimens attributed to the Middle Triassic Gracilisuchus (Fig. 2) is online (PDF). It includes the previously unpublished skull of PVL 4597 (Figs. 1, 2), which the large reptile tree (LRT, 1592 taxa) nests apart from Gracilisuchus, as the last common ancestor of all archosaurs (crocs + dinos only) with or without its skull. We reviewed Gracilisuchus yesterday, so this addition to the LRT is timely.

Figure 1. The skull of PVL 4597 in several views from the 2013 PhD thesis of A. Lecuona. Colors added.

The differences between PVL 4597 and Gracilisuchus are few (Fig. 2).
So, it is not a surprise that Lecuona considered them congeneric.

However,
the differences are fewer between PVL 4597 and its ancestor, Turfanosuchus (Fig. 4), and  its descendant, Herrerasaurus, the last common ancestor of dinosaurs traditionally and in the LRT. 19 additional steps are added when PVL 4597 is forced to nest with Gracilisuchus in the LRT.

FIgure 2. Comparing PVL 4597 to Gracilisuchus. Despite their many similarities, these two do not nest together in the LRT. Taxon exclusion is the issue with the PhD dissertation and the use of an invalidated analysis from Nesbitt 2011.

Basal members of large clades
are sisters to basal members of sister clades (Fig. 3). We compare those taxa with one another, ignoring the more derived members.

Figure 3. Subset of the LRT focusing on basal archosaurs and their immediate ancestors.

Here (Fig. 4) are the skulls of
Turfanosuchus and Herrerasaurus, taxa closer to PVL 4597 than PVL 4597 is to Gracilisuchus is in the LRT. The long-awaited skull confirms the nesting of the post-crania.

Figure 4. Skull of Turfanosuchus compared to Herrerasaurus, the basalmost dinosaur.

Without PVL 4597, 
the LRT still nests Turfanosuchus and basal bipedal crocs close to the base of the Dinosauria, contra the results of other studies that generally do not include those taxa.

Unfortunately,
Lecuona’s PhD thesis employed a borrowed and flawed cladogram on which she mistakenly trusted in: Nesbitt 2011. Even though Lecuona’s revised cladogram includes the basal bipedal crocs (which nest at derived nodes in her thesis), earlier we dismantled Nesbitt 2011 in a 7-part series ending here. Rescored Nesbitt 2011 resembles the LRT.

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References
Lecuona A 2013. Anatomía y relaciones filogenéticas de Gracilisuchus stipanicorum y sus implicancias en el origen de Crocodylomorpha. PhD thesis. PDF
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.

wiki/Gracilisuchus

Teyujagua paradoxa: still no paradox in the LRT

Back in 2016 Pinheiro et al.
introduced readers to a small Early Triassic proterosuchid without much of an antorbital fenestra, Teyujagua paradoxa (Fig. 1). Back then a smaller large reptile tree (LRT, subset Fig. 2) nested Teyujagua as one of several smaller descendants of Proterosuchus without an antorbital fenestra. Based on taxon exclusion Pinheiro et al. 2016 mistakenly described Teyujagua as, “transitional in morphology between archosauriforms and more primitive reptiles…as the sister taxon to Archosauriformes.” Evidently they were looking for greater glories than Teyujagua actually represented.

Figure 1. Teyujagua compared to sister taxa, including Youngoides, Proterosuchus and Chasmatosaurus. Teyujagua is a phylogenetic miniature in which the antorbital fenestra became a vestige.

 

This year (2019) Pinheiro et al. returned to Teyjagua
They wrote, “The evolution of the archosauriform skull from the more plesiomorphic configuration present ancestrally in the broader clade Archosauromorpha was, until recently, elusive.”

This is a bogus statement.
The LRT found a series of terrestrial younginiforms basal to archosauriforms and protorosauria. You read about them here in 2011. All the authors had to do was google Teyjagua to find the data needed to overturn their hypothesis.

Pinheiro et al. 2019 continue, 
“This began to change with the discovery and description of Teyujagua paradoxa, an early archosauromorph from the Lower Triassic Sanga do Cabral Formation of Brazil. In addition to providing new details of the anatomy of T. paradoxa, our study also reveals an early development of skull pneumaticity prior to the emergence of the antorbital fenestra.”

This is an backwards statement.
The LRT found Teyujagua was losing an antorbital fenestra, not gaining one. Adding taxa would have solved this problem for Pinheiro et al. 2019, as suggested three years ago.

Pinheiro et al. 2019 continue,
‘The data presented here provide new insights into character evolution during the origin of the archosauriform skull.”

The actual origin of the archosauriform skull
according to the LRT (Fig. 2). occurs in a list of excluded taxa ending with Youngoides romeri FMNH UC1528. As before Teyujagua remains a sister to Chasmatosaurus alexandri NMQR 1484 and is therefore a dead end taxon, basal to nothing.

Figure 2. Cladogram of basal archosauriforms. Note the putative basalmost archosauriform, Teyujagua (Pinheiro et al 2016) nests deep within the proterosuchids. The 6047 specimen that Ewer referred to Euparkeria nests as the basalmost euarchosauriform now.

This should be embarrassing to the authors
when an amateur without a science degree of any firsthand access to  the specimen can tell the PhDs they didn’t included enough taxa to understand what they were dealing with. Sadly, this is not the first time, and it won’t be the last. The LRT is a powerful tool, free for all to use.

Figure 3. Youngoides romeri FMNH UC1528 demonstrates an early appearance of the antorbital fenestra in the Archosauriformes. This specimen is the outgroup to Proterosuchus, the traditional basal member of the Archosauriformes.

Figure 4. Click to enlarge. Updated image of various proterosuchids and their kin. When you see them all together it is easier to appreciated the similarities and slight differences that are gradual accumulations of derived taxa. Teyujagua is a deadened taxon, less glorious than Pinheiro et al. 2016 and 2019 wish it was.

A paper on Youngoides romeri and the origin of the Archosauriformes
can be read online here at ResearchGate.org. It was rejected by the referees.

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References
Pinheiro FL, França MAG, Lacerda MB, Butler RJ and Schultz CL 2016. An exceptional fossil skull from South America and the origins of the archosauriform radiation. Nature Scientific Reports 6:22817 DOI: 10.1038/srep22817.
Pinheiro FL, De Simao-Oliveira D and Butler RJ 2019. Osteology of the archosauromorph Teyujagua paradoxa and the early evolution of the archosauriform skull.
Zoological Journal of the Linnean Society, zlz093
https://doi.org/10.1093/zoolinnean/zlz093
https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlz093/5585773

https://pterosaurheresies.wordpress.com/2016/03/13/teyujagua-not-transitional-between-archosauriforms-and-more-primitive-reptiles/

 

Digging into another cladogram, pt. 6

I hate seeing this week-long experiment drag out like this…
but there is a lot of work here and slow, but steady progress. Still not finished. Thought you’d like to see the progress and transformation of the cladogram (Fig. 1). Click the [previous] button above to see earlier iterations of this work.

Re-scoring a reduced Nesbitt et al. 2017 matrix
A surprisingly large number of data matrix boxes in Nesbitt et al. 2017 were left unfilled, so I’m filling them. The resulting cladogram (Fig. 1) is getting to look more and more like the large reptile tree (LRT, 1560 taxa). Of those scores that needed to be re-scored, most were perplexingly obvious.

Figure 1. Getting close to the end cladogram reduced and rescored from Nesbitt et al. 2017.

The clade Phytodinosauria
now nests derived from the Herrerasaurus clade, as in the LRT. The Silesaurus clade now nests within the Poposauria, as in the LRT. The next step is to figure out what is attracting giant terminal taxa in the Rauisuchia, like Postosuchus, to some much smaller, not-quite-basal Crocodylomorpha (Fig. 1) in Nesbitt et al. 2017 (Fig. 1), contra the LRT. This traditional attraction, creating the invalidated clade Pseudosuchia, is the basis for including many more clades in the Archosauria than just the crocs + dinos, as recovered in the LRT.

Here’s a Nesbitt et al. 2017 character I thought oddly worded:
“Maxilla ventral portion: Mediolateral height greater than dorsoventrally length.” Typically mediolateral refers to width. Dorsoventral refers to height. Data entries like this I just left alone.

I will get to the comments
from the past week once this project reaches a conclusion. Sorry for the delay. I’d rather not answer to anything posted until the entire experiment is finished and all the pertinent images are uploaded (apparently server issues prevent this currently).

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References
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.
Nesbitt S et al. 2017. The anatomy of Teleocrater Rhadinus, an early avemetatarsalian from the lower portion of the Lifua Member of the Manda Beds (Middle Triassic). Journal of Vertebrate Paleontology 142-177. https://doi.org/10.1080/02724634.2017.1396539