You heard it here first… four years ago. Diandongosuchus is a stem phytosaur.

WordPress.com timestamps every post
This one comes from August 29, 2012.Diandongosuchus. Not a basal poposauroid. A basal phytosaur.” Click here to see the original discovery and post. Click here to see the ReptileEvolution.com page on Diandongosuchus (Fig. 1). Click here to see the nesting of Diandongosuchus in the large reptile tree.

Diandongosuchus nests as a basal phytosaur when choristoderes and basal younginoids are included, far from Qianosuchus, which also does not nest with poposaurs, which are all bipedal (or formerly bipedal) herbivores, a far cry from Diandongosuchus.

Figure 1. Diandongosuchus nests as a basal phytosaur when choristoderes and basal younginoids are included, far from Qianosuchus, which also does not nest with poposaurs, which are all bipedal (or formerly bipedal) herbivores, a far cry from Diandongosuchus.

 

 

Today, delivering a SVP abstract, Stocker et al. report
“… A recently described taxon from the Ladinian of China, Diandongosuchus, was proposed as a poposauroid largely because of similarities (e.g., premaxillary elongation) to the basal form Qianosuchus. We reassessed the systematics of Diandongosuchus within an extensive analysis of archosauriform phylogenetic relationships and show that Diandongosuchus is not a poposauroid, but is the sister taxon to all phytosaurs. First-hand evaluation of Diandongosuchus reveals an interdigitated premaxilla-maxilla suture, wide distal end of the quadrate, broad postorbital-squamosal bar, hooked coracoid, broad interclavicle, and backswept scapula, all apomorphies of Late Triassic phytosaurs. Our reinterpretation of Diandongosuchus as a phytosaur indicates that the postcranial modifications of phytosaurs occurred well prior to rostral elongation, supports that the clade was located across Pangea, and hypothesizes saltwater tolerance….”

Since some things cannot be discovered twice
I thought this might interest the readers of PterosaurHeresies that some things done here are later confirmed by other workers when they expand their taxon lists. Not sure how I feel about the Stocker team claiming credit for this…

You’ll note
the Stocker team could have read about their ‘reinterpretation” at any time over the past four years by googling “Diandongosuchus“. Not sure how long it will take Wikipedia to catch up. As I write this on the 26th, Wiki is respecting the SVP embargo.

BTW
the Stocker team thesis on the origin of the long snout on phytosaurs can be traced beyond Diandongosuchus to its ancestry within the wide variety of Proterosuchus, Elaphrosuchus and Chasmatosaurus specimens in the LRT. It’s a powerful tool, available free to everyone.

Not sure if there will be any credit given for this
from Dr. Naish after all the discredit heaped upon ReptileEvolution.com earlier. This is what some would call vindication, and others would call confirmation, of a tested hypothesis of interrelationships. Test your enigmas by expanding your taxon inclusion lists and let’s see how many other confirmations (and refutations if they arise) we can find together.

References
Stocker MR, Nesbitt SJ, Zhao L-J, Wu X-C and Li C 2016. Mosaic evolution in phytosauria: the origin of longsnouted morphologies based on a complete skeleton of a phytosaur from the Middle Triassic of China. Abstracts of the Society of Vertebtate Paleontology meeting 2016.

 

 

 

The origin of the Parasuchia

Parasuchians (phytosaurs) are those very croc-like Triassic swamp giants with a nostril rising on a bony volcano almost between their eyes (Fig. 1).

A selection of phytosaurs (parasuchians).

Figure 1. A selection of phytosaurs (parasuchians).

Parasuchians all have a similar appearance. 
The question is, where did they come from? Which taxa are their closest ancestors?

Nesbitt (2011) 
nested parasuchians between Euparkeria and Archosauria (Ornithodira (including pterosaurs) + pseudosuchia. Apparently it didn’t matter to Nesbitt’s study that his parasuchians didn’t resemble the most closely nested taxa.

Brusatte et al. (2010)
nested parasuchians between Proterochaampsidae and Aetosauria + the rest of the Pseudosuchia; or (when pterosaurs were removed) between Revueltosaurus and Aetosauria + the rest of the Pseudosuchia. In both cases the Avemetatarsalia (pterosaurs + dinosaurs and kin) were considered closely related. So again, not many taxa here display a gradual accumulation of parasuchian traits.

According to the large reptile tree
everything becomes much more clear and a gradual accumulation of parasuchian traits is clearly visible in ancestral taxa (Fig 2).

Figure 2. The origin of the Parasuchia (Phytosauria) with Diandongosuchus, Mesorhinosuchus and related taxa.

Figure 2. The origin of the Parasuchia (Phytosauria) with Diandongosuchus, Mesorhinosuchus and related taxa. This series demonstrates a gradual accumulation of parasuchian traits. It would be nice to find one with the nostrils midway on the snout.

Taxon inclusion is key to this understanding. Using specimens rather than suprageneric taxa is also important.

References
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.

Teraterpeton nests with Trilophosaurus

Updated January 06, 2019
with new data in the form of photos leading to a new nesting of Teraterpeton with Trilophosaurus, despite the many differences (Fig. 1).

Figure 1. Skulls of Teraterpeton and Trilophosaurus compared.

Figure 1. Skulls of Teraterpeton and Trilophosaurus compared.

The enigmatic Teraterpeton (Fig. 1), originally (Sues 2003) considered a relative of Trilophosaurus largely due to its toothless beak and lack of a lateral temporal fenestra. Now that nesting is confirmed.

Teraterpeton-skull-588

Figure 2. Teraterpeton skull. Note the confluent naris and antorbital fenestra.

Teraterpeton is so weird,
t is no wonder it has remained an enigma for so long. Nesting such enigmas is exactly what the large reptile tree (not updated yet) is for. Earlier Teraterpeton nested with Tropidosuchus in the large reptile tree, but a mismatch that needed repairing.

Teraterpeton hrynewichorum (Sues 2003) Late Triassic, ~215 mya, was described as euryapsid (lacking a lateral temporal fenestra) and possibly related to the rhynchocephalian, Trilophosaurus on that basis, but with a stretched out rostrum and far fewer, smaller teeth. The lateral temporal fenestra has been shortened so much that the lateral temporal fenestra has closed up. So, it’s still a diapsid morphology. The teeth had the multiple cusps of a plant eater. The pedal(?) unguals are robust, but note the disparate sizes.

References
Sues H-D 2003. An unusual new archosauromorph reptile from the Upper Triassic Wolfville Formation of Nova Scotia. Canadian. Journal of Earth Science 40(4): 635-649.

 

Diandongosuchus palate

Diandongosuchus fuyuanensis was originally (Li et al. 2012) nested with Qianosuchus and the poposaurids, but it shares very few traits with these taxa as blogged here. This middle Middle Triassic, croc-mimic was derived from a croc-like specimen of YounginaBPI 2871 and a sister to Diandongosuchus gave rise to the parasuchians, Paleorhinus and Parasuchus. Proterochampsa was a sister and Diandongosuchus is not far from long-legged Chanaresuchus and Doswellia + Choristodera.

We looked at Diandongosuchus earlier here and in five other posts.

The palate is virtually invisible (Fig. 1), seen only through the naris, antorbital fenestra, orbit and a smidgeon between the jaws on the underside. The basisphenoid is not visible, probably hidden beneath a mandible. But the cultriform process is visible. So, with available data, here is the palate of Diandongosuchus reconstructed in a step-by-step process using the infamous DGS (digital graphic segregation), which I submit, still has value as shown below.

Figure 1. Using DGS to tease out the palate elements of Diandongosuchus. Color tracings enable the important elements of the skull to be layered upon one another to see where things match up and where they don't. A sliver here might be connected to another sliver there. I was surprised to see how narrow the skull was, even before crushing.

Figure 1. Using DGS to tease out the palate elements of Diandongosuchus. Color tracings enable the important elements of the skull to be layered upon one another to see where things match up and where they don’t. A sliver here might be connected to another sliver there. I was surprised to see how narrow the skull was, even before crushing.

Diandongosuchus is just another big, nasty, robust younginid, but developing along separate lines than Proterosuchus and Garjainia, which have a similar heritage. Converging with Gargainia, the skull of Diandongosuchus was taller than wide, which is different than all of its closest sisters.

The deep cheeks in this taxon are further developed in parasuchians, which raised the orbit to the top of the skull. The vomers are very long and I suspect that the maxillary palatal plates supported it. You can see rather plainly in Chanaresuchus, in which the internal nare are divided into fore and aft openings by the advancing maxilla. In parasuchia the vomer is very short because the premaxilla is very long.

References
Li C, Wu X-C, Zhao L-J, Sato T and Wang LT 2012. A new archosaur (Diapsida, Archosauriformes) from the marine Triassic of China, Journal of Vertebrate Paleontology, 32:5, 1064-1081.

wiki/Diandongosuchus

Diandongosuchus – another giant younginid

Earlier we looked at Diandongosuchus, which was originally considered a poposaurid (Li et al. 2012). The large reptile tree (now needs to be updated) nested Diandongosuchus at the base of the parasuchians and proterochampsids (including the biped, Lagerpeton). It’s easy to see the resemblance.

Today we’ll revise the skull of a tiny Youngina, BPI 2871, which is the basal taxon in this lineage (more primitive than Diandongosuchus). Seems the rostrum of the BPI specimen was probably crushed dorsoventrally, resulting in a false concave rostral profile. The posterior skull is missing, but it can be restored closer to Diandongosuchus now that the phylogenetic analysis shows the close relationship.

Figure 1. The large reptile tree nests these two taxa as sisters despite their size difference. With greater size came the development of an antorbital fenestra, independent of the one developing in other Younginids leading toward archosauriformes beginning with Proterosuchus.

Figure 1. The large reptile tree nests these two taxa as sisters despite their size difference. With greater size came the development of an antorbital fenestra, independent of the one developing in other Younginids leading toward archosauriformes beginning with Proterosuchus.

Evolution works in baby steps.
That’s why maximum parsimony (fewest morphological changes) is still the best route for finding ancestors and descendants and for filling in missing parts by the method of phylogenetic bracketing. Diandongosuchus also gives us clues as to the post-crania of the BPI 2871 specimen of Youngina, with reservations regarding the great size difference.

I’d like to see the BPI 2871 specimen, but the last I heard (several years ago) it was ‘on loan’ and had not been returned.

Some workers, Gow (1975), among them, consider the BPI 2871 specimen congeneric with other Youngina and Younginoides specimens, with all apparent changes in morphology due to crushing. While that is likely true to a certain extent, there are differences that can be scored in phylogenetic analysis to reveal their differences and relationships. And you can always take out the crushing to check out prior hypotheses.

Earlier we looked at Garjainia as another giant younginid.

References
Gow CE 1975. The morphology and relationships of Youngina capensis Broom andProlacerta broomi Parrington. Palaeontologia Africana, 18:89-131.
Li C, Wu X-C, Zhao L-J, Sato T and Wang LT 2012. A new archosaur (Diapsida, Archosauriformes) from the marine Triassic of China, Journal of Vertebrate Paleontology, 32:5, 1064-1081.

wiki/Diandongosuchus
wiki/Youngina

Strange Bedfellows – Nesbitt (2011) – part 4 – Parasuchus

Sometimes we miss the big picture.
Here then, for your approval and disapproval are comparisons between closest kin found by the Nesbitt (2011) tree versus those found by the large reptile tree. We started at the base with Mesosuchus. Earlier we looked at Vancleavea. Yesterday we looked at Euparkeria. Today we look at the phytosaur, Parasuchus, surrounded by Euparkeria on primitive side and the Ornithosuchidae (represented here by Ornithosuchus) and the Pterosauria led by Eudimorphodon on the derived side (Figs. 1, 2)

Figure 1. The nesting of pterosaurs in Nesbitt (2011), the current "Gold Standard" for the nesting of archosaurs and their relatives. Unfortunately, pterosaurs don't belong here, as can quickly be seen by side-by-side comparisons.

Figure 1. The nesting of pterosaurs in Nesbitt (2011), the current “Gold Standard” for the nesting of archosaurs and their relatives. Unfortunately, pterosaurs don’t belong here, as can quickly be seen by side-by-side comparisons and the other taxa need to be reordered for a better fit.

Parasuchus Kin According to Nesbitt (2011)
Here (Fig. 2) are the selected Nesbitt (2011) sisters for visual comparison. I don’t see any gradual evolution (accumulation of derived characters) here. Do you?

Pterosaur closest kin according to Nesbitt 2011.

Figure 2. The phytosaur, Parasuchus, surrounded by putative sisters according to Nesbitt 2011. Euparkeria was more primitive. Eudimorphodon and Ornithosuchus were more derived. Does anyone else see a problem here?? Why was this result NOT widely criticized? There is no gradual accumulation of derived characters here leading toward the bottom two taxa. 

Parasuchus Kin According to the Large Reptile Tree
The large reptile tree found Proterochampsa and the choristoderans, Cteniogenys and Lazarussuchus to be closer than Euparkeria and Ornithosuchus because they share a long narrow rostrum and dorsal nares among a suite of other traits.

Parasuchus and kin including Proterochampsa, Lazarussuchus, Youngina and Cteniogenys.

Figure 3. Parasuchus and kin including Proterochampsa, Lazarussuchus, Youngina and Cteniogenys. Note the dorsal placement of the naris on a narrow rostrum and the evolution of it moving posteriorly. Here the antorbital fenestra makes an appearance convergent with that seen in Proterosuchus descending from a sister to Prolacerta. Parasuchus is a terminal taxon in that only other parasuchians (phytosaurs) evolved from it. 

One look at these results brings immediate understanding that there’s something wrong in the matrix that produces such strange bedfellows.

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
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.

Introducing the Pararchosauriformes

Traditional studies (eg. Nesbitt 2011) nest all Archosauriformes in a ladder of taxa that  includes a major split between the so-called “Pseudosuchia” (aetosaurs, poposaurs, rauisuchids, crocodylomorphs and several individual genera) and the so-called “Avemetatarsalia” (pterosaurs and dinosauriforms).

The Pararchosauriformes. Lagerpeton is the most derived taxon.

Figure 5. The Pararchosauriformes. Lagerpeton is the most derived taxon.

The present large heretical study, that includes many times more taxa, recovers a major split at the grade of Youngina and Youngoides. One branch includes the taller, narrower skull forms descending from sisters to Proterosuchus. The other branch includes the wider, lower skull forms that include choristoderes, phytosaurs and chanaresuchids along with related taxa.

Taxon Exclusion is the Problem 
Traditional studies do not include dozens of key taxa due to a priori exclusion policies based on tradition and prejudice. The present heretical study minimizes those prejudices by including specimens from every corner of the reptile family tree.

Pararchosauriformes.

Figure 1. The Pararchosauriformes. Only the larger taxa are visible here.

It All Begins with Youngoides
Youngina and Youngoides (Fig. 2) have been recognized for decades as basal taxa to the Archosauriformes. That’s absolutely correct. What hasn’t been recognized is that the variety in Youngina is real. The skulls look crushed and distorted, but some really are taller than wide or wider than tall. Basically, that’s what sets euarchosauriforms (Proterosuchus and descendants) apart from pararchosauriforms (choristoderes and desendants). The nares drift dorsally. The rostrum becomes elongated. The orbits either are or are not elevated above the rostrum. After those basal traits, evolution produced bipeds, croc-like forms and pachypleurosaur-like forms, along with at least one plant-eater in both branches of the Archosauriformes.

Several choristoderes

Figure 3. Several choristoderes (in white), their predecessor and sisters (in yellow).

Choristodera
Basal pararchosauriforms, like Doswellia and the Choristodera (Fig. 2), did not have an antorbital fenestra. These enlarged descendants of Youngoides elongated the snout and moved the naris dorsally.  Lazarussuchus lost the lateral temporal fenestra and further elongated the pre-narial premaxilla.

Proterochampsa
Currently known from a single published skull and an unpublished post-crania, Proterochampsa (Figs. 1, 2) is the most basal pararchosaur to sport an antorbital fenestra and no fossa surrounded it. This flat-skulled form was probably aquatic and short-legged like its sisters.

Phytosuchia/Parasuchia
The croc-like phytosaurs are a distinct clade sharing a long list of character traits. Even basal taxa have a longer rostrum than Proterochampsa.

Chanaresuchidae
Chanaresuchus and Tropidosuchus comprise the Chanaresuchidae, a clade of increasingly terrestrial forms culminating in the biped, Lagerpeton, a taxon commonly and mistakenly associated with dinosaurs by traditional workers.

Strangely, members of the Phytosauria and Chanaresuchidae have nested in traditional studies with pterosaurs, but this is patently ridiculous, a result of improper taxon inclusion and exclusion as demonstrated by the results of the large study.

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
Broom R 1914. A new thecodont reptile. Proceedings of the Zoological Society of London, 1914:1072-1077.
Gardner NM, Holliday CM and O’Keefe FR 2010. The braincase of Youngina capensis(Reptilia, Diapsida): New insights from high-resolution CT scanning of the holotype. Paleonotologica Electronica 13(3):online PDF
Gow CE 1975. The morphology and relationships of Youngina capensis Broom and Prolacerta broomi Parrington. Palaeontologia Africana, 18:89-131.
Olsen EC 1936. Notes on the skull of Youngina capensis Broom. Journal of Geology, 44 (4): 523-533.

Cerritosaurus – A Key Overlooked Taxon in the Pararchosauriformes

Cerritosaurus binsfeldi,

Figure 1. Cerritosaurus binsfeldi, Late Triassic, known only from a skull. Such a taxon was basal to Chanaresuchus and the chanaresuchids. It also would have been morphologically close to the ancestor of the phytosaurs (parasuchians) and not far from Proterochampsa given its resemblance to the RC 91 specimen of Youngoides.

Where are the Phytosaur and Chanaresuchid Ancestors?
There has been relatively little interest in finding ancestral taxa to the phytosaurs and chanaresuchids. Prior efforts have recovered questionable candidates. Nesbitt’s (2011) tome on archosaurs recovered Euparkeria nesting at the base of the Phytosauria.  He also recovered Vancleavea nesting at the base of the Proterochampsia (= Tropidosuchus + Chanaresuchus). Erythrosuchus nested basal to all the above taxa.

These Nestings Raise Red Flags
Phytosaurs and chanaresuchids were flat-headed archosauriformes with skulls wider than tall and nares located dorsally on the skull. The orbits were located high on the skull. The rostrum was narrow in dorsal view and the “cheeks” flared widely. The antorbital fenestra was small. By contrast the skulls of VancleaveaEuparkeria and Erythrosuchus were taller than wide, with narrow cheeks, lateral nares and the latter two had a large antorbital fenestra. Vancleavea did not have an antorbital, mandibular or upper temporal fenestra because indeed it was not related to archosaurs. Vancleavea was a thalattosaur as reported earlier. Nesbitt (2011) did not include other thalattosaurs in his analysis, so Vancleavea nested by default within the Archosauriformes. The large reptile study solves that shortcoming.

Cerritosaurus binsfeldi (Price 1946, Fig. 1) Late Triassic, ~210 mya, nests here between the Parasuchia and the base of the Chanaresuchidae within the Pararchosauriformes. Nesbitt (2011) briefly mentioned Cerritosaurus as a member of the Proterochampsia [a paraphyletic taxon]. With its short snout and generally primitive characters Cerritosaurus likely also resembled the common ancestor of the Choristodera, Parasuchia and Proterochampsa. It was also not far from the RC 91 specimen of Youngoides (Fig. 1).

Distinct from RC91Cerritosaurus had a skull with a downturned rostrum. The skull was box-like with distinct rims both anterior and posterior to the orbits. The nares opened dorsally. An antorbital fenestra appeared with a deep fossa. The dorsal squamosal flared posteriorly. The mandibular fenestra was enlarged. The retroarticular process ascended. The teeth were extremely long, which is an autapomorphy.

With its wide flat skull, dorsal nares and elevated orbits Cerritosaurus provides a nearly ideal transitional taxon linking the RC91 specimen of Youngoides to basal phytosaurs and chanaresuchids. It is certainly a superior candidate compared to the taller narrow skulls of Euparkeria and Erythrosuchus. Exclusion of Cerritosaurus by Nesbitt (2011) and others before him impaired those earlier studies.

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
Bonaparte JF 1971Cerritosaurus binsfeldi Price, tipo de uma nova família de tecodontes (Pseudosuchia-Proterochampsia). Anais da Academia Brasileira de Ciências, 43(Supl.): 417-422.
Kischlat E-E and Schultz CL 1999. Phylogenetic analysis of Proterochampsia (Thecodontia: Archosauriformes): Ameghiniana, v. 36, p. 13R.
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.
Price LI 1946. Sôbre um novo pseudosuquio do Triássico superior do Rio Grande do Sul: Boletim da Divisão de Geologia e Paleontologia, DNPM, v. 120, p. 7-38.

wiki/Cerritosaurus

Phytosaurs and their Sisters

The nesting of phytosaurs (parasuchians) has moved around quite a bit.
Gauthier (1984) nested Parasuchia between Proterochampsa and AetosauriaBenton and Clark (1985) nested Parasuchia between Ornithosuchidae and Gracilisuchus.  Bennett (1996) found Parasuchia nested with Suchia between Euparkeria and Ornithosuchia + Pterosauria. Sereno (1991) nested Parasuchia between Proterochampsa, Ornithosuchia and Dinosauromorpha. Benton (1999) nested Phytosauridae between Proterochampsidae and Stagonolepidae and Scleromochlus. Benton (2004) nested Phytosauridae with Gracilisuchus. Norrell (2006) and Nesbitt (2007) nested Parasuchia between Stagonolepidae and Pterosauria. (These were all referenced and illustrated n Nesbitt 2011, see below.)

A selection of phytosaurs (parasuchians).

Figure 1. A selection of phytosaurs (parasuchians).

The Latest Nesting
Nesbitt (2011) provided the latest and largest published tree. He nested phytosaurs as derived from Euparkeria and basal to two clades within the Archosauria. Ornithosuchidae was at the base of one branch and pterosaurs were at the base of the other.

It’s puzzling how aetosaurs, pterosaurs and Scleromochlus made earlier lists. They bear little to no resemblance to phytosaurs. It’s also noteworthy that there has been little consensus in prior studies.

It’s a shame that so many earlier studies eschewed generic taxa for suprageneric taxa. The mysteries remained mysteries. Sister taxa did not share many traits. The large study sheds light on the relationships of phytosaurs and all of the members of the Reptilia.

The sisters of Phytosaurs,

Figure 2. The sisters of Phytosaurs, including Cerritosaurus, Proterochampsa and the RC91 specimen of Youngoides. Click to enlarge.

Given All These Choices Where Does the Large Study Nest Phytosaurs?
Unfortunately only skulls are known for the closest sisters of phytosaurs. Those who nested Proterochampsa with phytosaurs were correct, as confirmed by  the large study. However, nobody mentioned Cerritosaurus, the phytosaurs’ other sister taxon. At the base of all three nests Youngoides minor. It lacks an antorbital fenestra. The Choristodera are also sisters and Doswellia is at the base of that large and varied clade. Chanaresuchus and its sisters are related beyond Cerritosaurus.

Phytosaur Family Tree
I have not attempted a phytosaur family tree. Paleorhinus (Fig. 2) and Parasuchus are generally considered basal phytosaurs.

Shared Traits?
A pair of dorsal and displaced nares distinguish phytosaurs from all euarchosauriformes (Euparkeria, Ornithosuchidae, Gracilisuchus, Dinosauromorpha, etc.) and pterosaurs. Proterochampsa shares that trait. Cerritosaurus and the chanaresuchids do too, but to a lesser extent.

A skull that is wider than tall is also a shared trait. The rostrum is elongated. The top of the skull is narrower than the base at the jaw joint. The top of the skull is flat across the upper temporal fenestra. The orbits are elevated or on top of a flattened skull. The postfrontal and postorbital are fused. An antorbital fenestra developed independently in this clade. Phytosaurs share with chanaresuchids a skull longer than half the presacral length of cervicals. Certainly many of these traits find convergence elsewhere on a tree where convergence runs rampant. Even so, the rules of parsimony place phytosaurs with these pararchosauriformes and the clade is a sister to the euarchosauriformes.

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
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.