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.

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.

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.

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.


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

CM 73372 reconstructed

So far as I know,
Carnegie Museum specimen CM 73372 (Fig. 1) does not yet have a name, nor has it been reconstructed. Weinbaum 2013 included this skull-less image in a Postosuchus study, which makes sense at first sight, given the size, proportions and age (Late Triassic) of both specimens. The large reptile tree (LRT, 1394 taxa) nests CM73372 close to Postosuchus, but closer to Teratosaurus and Smok. Since Teratosaurus is known from skull-only data at present, there is loss of resolution at that node.

Figure 1. CM73372 in situ and reconstructed using DGS methodology. At first glance it seems to be a biped with short fingers, like Postosuchus. In situ image from Weinbaum 2013.

Figure 1. CM73372 in situ and reconstructed using DGS methodology. At first glance it seems to be a biped with short fingers, like Postosuchus. In situ image from Weinbaum 2013.

This is an interesting taxon because
Lucuona et al. 2017 and others nest it basal to Crocodylomorpha. Weinbaum considered it a member of the Archosauria and the Paracrocodylomorpha, a clade the large reptile tree (LRT, 1394 taxa) does not recover.

According to Wikipedia
Loricata was an early name for an order that includes crocodilesalligators, and gharials, although the order is now referred to as Crocodylia. Nesbitt 2011 defined it as the most inclusive clade containing Crocodylus niloticus (the Nile crocodile), but not the extinct Poposaurus gracilisOrnithosuchus longidens, or Aetosaurus ferox. In the LRT, that clade is a junior synonym for Crocodylomorpha, since Poposaurus is a member of the proximal outgroup, the Poposauria. In traditional paleontology Loricata includes Rauisuchia and Crocodylomorpha. If so, then it also includes Poposauria and Dinosauria, but that was not the original intention of this definition.

Paracrocodylomorpha is another clade invalidated by the LRT because it includes Poposauria and Loricata. In the LRT Rauisuchia is the basal clade, followed roughly by Poposauria and Archosauria (crocs + dinos only).

You might recall,
the Nesbitt 2011 cladogram finds phytosaurs arising from a sister to the distinctly different Euparkeria. Taxon exclusion is the problem here. Nesbitt 2011 also finds Ornithosuchia (Ornithosuchus and kin) and Pterosauria forming the first dichotomy arising from a basal sister to Phytosauria. Again taxon exclusion is the problem here, yet widely accepted in the paleo community for reasons unknown (except, possibly ease of use and fear of change). We talked about other odd and topsy-turvy sister taxa recovered by Nesbitt 2011 earlier here, here and here, three blog posts in a nine-part series.

This addition of CM73372 to the LRT sets us up
for tomorrow’s discussion on basal archosaurs.

References
Lecuona A, Desojo JB and Pol D 2017. New information on the postcranial skeleton of Gracilisuchus stipanicicorum (Archosauria: Suchia) and reappraisal of its phylogenetic position. Zoological Journal of the Linnean Society, 2017, XX, 1–40.
Weinbaum J 2013. Postcranial skeleton of Postosuchus kirkpatricki (Archosauria:
Paracrocodylomorpha), from the Upper Triassic of the United States. Geological Society London Special Publications · August 2013.

wiki/Paracrocodylomorpha
wiki/Loricata

Not Arizonasaurus, but Postosuchus, made the giant Isochirotherium tracks

A recent paper by Diedrich (2015) purported to match the Arizonasaurus to giant Isochirotherium tracks from the Middle Triassic of Germany (Fig. 1).

The problem is,
no manus or pes are known for Arizonasaurus. Furthermore, all related taxa in the large reptile tree have digit 3 the longest, and all digits are elongate. The giant Isochirotherium tracks indicate that both digits 2 and 3 are the longest, and they are short. So matching candidates have to be found elsewhere, not close to Arizonoasaurus (although the size and time are right!).

Among the 504 taxa in the large reptile tree that are possible candidates with digits 2 and 3 the longest are Erythrosuchus (Fig. 1), Shansisuchus, Lotosaurus and the Postosuchus alisonae (Peyer 2008, Fig. 1). It turns out that only the latter is the best match when scaled up to the size of P. kirkpatrchicki (Chatterjee 1985, Fig. 1).

Figure 1. Giant Isochirotherium tracks matched to Postosuchus alisonae scaled up to the size of P. kirkpatrcki.

Figure 1. Giant Isochirotherium tracks matched to Postosuchus alisonae scaled up to the size of P. kirkpatrcki. Click to enlarge. This taxon was not considered originally because it is Late Triassic and the tracks are Middle Triassic.

Postosuchus was not mentioned in the text
because Diedrich (recent email) knew Postosuchus was Late Triassic, not Middle Triassic. He did not accept the idea that between the origin, radiation and extinction of Postosuchus there might have been a Middle Triassic relative.

Diedrich also saw the small manus tracks and assumed they were produced by a large poposaurid. Unfortunately, Arizonasaurus does not nest with poposaurids either. And poposaurids, other than Lotosaurus, do not match the track morphology.

It would have been helpful,
I suppose, to do what I did and make a list of possible candidates from a large list, AND THEN delete the possible candidates one by one as bad matches. Other than that phylogenetic bracketing mismatch, Diedrich does good work with excellent graphics. It took a leap of faith, I suppose to match tracks to a taxon for which no manus or foot is known.

C. Diedrich writes:
“Watch my ARTE docu – there you see Arizonasaurus (Ticinosuchus and Macrocnemus) walking in my point of view combining trak/sleketal records”:http://www.youtube.com/watch?v=b9GcVmb6OtE

References
Chatterjee S 1985. Postosuchus, a new Thecodontian reptile from the Triassic of Texas and the origin of Tyrannosaurs. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 309 (1139): 395–460. doi:10.1098/rstb.1985.0092.
Diedrich C 2015.
Isochirotherium trackways, their possible trackmakers (?Arizonasaurus): intercontinental giant archosaur migrations in the Middle Triassic tsunami-influenced carbonate intertidal mud flats of the European Germanic Basin  Carbonates and Evaporites  DOI 10.1007/s13146-014-0228-z
Novak SE 2004. A new specimen of Postosuchus from the Late Triassic Coelophysis Quarry, siltstone member, Chinle Formation, Ghost Ranch, New Mexico. M.S. thesis, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
Peyer K Carter, JG, Sues H-D, Novak SE, and Olsen PE 2008. A new Suchian Archosaur from the Upper Triassic of North Carolina. Journal of Vertebrate Paleontology 28 (2): 363–381. doi:10.1671/0272-4634(2008)28[363:ANSAFT]2.0.CO;2.

A closer look at Sikannisuchus huskyi

Earlier we looked at the skull roof of Sikannisuchus. Unfortunately, I ignored those long mandible bits and pieces. These give us more clues to restore the missing parts in lateral view (Fig. 1).

Sikannisuhus huskyi restored on must a view bits and pieces.

Sikannisuhus huskyi restored on must a view bits and pieces. Nesting with Postosuchus provides clues to the shapes of the missing parts. That’s a nice long skull. Must have been a BIG reptile.

If I made any errors, or the clues point in another direction, let me know.

References
Nicholls EL, Brinkman DB and Wu K-C 1998. A new archosaur from the Upper Triassic
Pardonet Formation of British Columbia. Canadian Journal of Earth Science 35: 1134–1142.

Arizonasaurus vs Spinosaurus

Two unrelated reptiles
evolved similar morphologies, Arizonasaurus and Spinosaurus (Fig. 1), a long rostrum filled with sharp teeth, a bipedal configuration and enormous neural spine arising from the dorsal vertebrae. One was a giant. The other about waist high. Seen here together for the first time…

Figure 1. Spinosaurus and Arizonsaurus, together for the first time. The similarities are obvious and intriguing.

Figure 1. Spinosaurus and Arizonsaurus, together for the first time. The similarities are obvious and intriguing. Spinosaurus courtesy of Scott Hartmann.

Spinosaurus is a famous giant theropod dinosaur. Arizonasaurus is none of these things. It’s a member of a clade that has no name, but arose from basal rauisuchids, like Venjukovia. It was a sister to Ticinosuchus + Aetosaurs and Yarasuchus + Qianosuchus, none of which have much of a sail back. I thought comparing these two might provide clues to their convergent looks.

Arizonasaurus comes from the Middle Triassic Moenkoepi Formation, which included fresh water and a diverse fauna. Earlier we looked at the possibility that this predator was bipedal, based on the very small pectoral girdle and very deep (for its time) pelvic girdle, almost like that of T-rex, but more gracile. Relatives include fish eaters, like long-necked Yarasuchus and plant eaters, like aetosaurs. So this is already a diverse clade that no doubt will provide many surprising morphologies in the future. Originally described as a prestosuchid rauisuchian, Brusatte et al. (2010) nested it with poposaurs. In the large reptile tree poposaurs nest a little closer to dinosaurs and basal crocs.

Spinosaurus comes from the Middle Cretaceous of northern Africa, which, at the time included tidal flats, mangrove forests and several other giant theropods. Only a few other dinosaurs had such long neural spines. The question is, where they more like sails, and aid in thermoregulation? Or did they support a buffalo-like hump of fat? Spinosaur relatives, all smaller, did not sport much of a sail back. So whatever its utility was, it was unique.

Sail backs seem to spring up occasionally and quickly around the reptile family tree. They never seem to last.

Moving on
to those long jaws, Spinosaurus was considered a quick-strike artist, feeding on everything from fish to small dinosaurs, but with that size it could have taken on any prey. No such claims have been made for Arizonasaurus, perhaps because not much of the skull is known. But the teeth were sharp

My take
I have no expertise and no stake in the hump vs. sail argument. Since these sails seem to come and go rather quickly, my opinion is they are literally a flash in the pan, thus they have no real utility and are only for show… secondary sexual traits. Popular one day, not so popular the next. The blessing probably becomes a curse over time, as the sail gets bigger, so the trait and the animal disappears. The neural spines are broad because they have “roots” that are broad, unlike Dimetrodon and like Sphenacodon.

References
Bailey JB 1997. Neural spine elongation in dinosaurs: sailbacks or buffalo-backs?. Journal of Paleontology 71 (6): 1124–1146.
Butler RJ, Brusatte SL, Reich M, Nesbitt SJ, Schoch RR, et al. 2011. The Sail-Backed Reptile Ctenosauriscus from the Latest Early Triassic of Germany and the Timing and Biogeography of the Early Archosaur Radiation. PLoS ONE 6(10): e25693. doi:10.1371/journal.pone.0025693 Plos One paper
Nesbitt SJ 2003. Arizonasaurus and its implications for archosaur divergence. Proceedings of the Royal Society, London B (Suppl.) 270, S234–S237. DOI 10.1098/rsbl.2003.0066
Nesbitt SJ, Liu J and Li C 2010. A sail-backed suchian from the Heshanggou Formation (Early Triassic: Olenekian) of China. Transactions of the Royal Society of Edinburgh 101 (Special Issue 3-4):271-284.
Welles SP 1947 Vertebrates from the Upper Moenkopi Formation of the Northern Arizona. Univ. California Publ. Geol. Sci. 27, 241–294.
Wu X-C 1981. The discovery of a new thecodont from north east Shanxi. Vertebrata PalAsiatica 19: 122–132.

wiki/Arizonasaurus
wiki/Ctenosauriscus

Revueltosaurus: closer to Aetosaurus? or to Fugusuchus?

This post was updated December 8, 2014 with a new nesting of Revueltosaurus with Fugusuchus as a basal erythrosuchid. 

Yesterday we saw a higher resolution Revueltosaurus skull in lateral view and we noted a disagreement in the phylogenetic nesting of this Late Triassic oddball.

According to Nesbitt (2011)…
Nesbitt (2011) nested the odd herbivorous Triassic archosauriform, Revueltosaurus, at the base of the aetosaurs, including Aetosaurus and Stagonolepis. Outgroups include an unresolved clade including Gracilisuchus, Turfanosuchus and Ticinosuchus. Outgroups to this clade include Riojasuchus and Ornithosuchus (= Ornithosuchidae) at the base of the “Pseudosuchia“. Wiki follows Nesbitt (2011).

According to Parker (2014?)…
William Parker, the discoverer of the twelve-specimen nest of Revueltosaurus skeletons, will soon publish a large monograph on this genus. His analysis will also nest Revueltosaurus with aetosaurs. He’s very sure of that.

Figure 1. Revueltosaurus compared to its big sister, Fugusuchus, a basal erythrosuchid.

Figure 1. Revueltosaurus compared to its big sister, Fugusuchus, a basal erythrosuchid.

According to the large reptile tree…
On the other hand, the large reptile tree does not recover the Nesbitt tree topology, but finds Revueltosaurus nests with Fugusuchus (Fig. 1) at the base of the Erythrosuchidae. To move Revueltosaurus to the Aetosauridae requires an additional 35 steps. t.

Like Aetosaurs:
Revueltosaurus is a heavily armored quadruped and a plant eater (judging by its teeth). I’m told by Parker the following traits are identical in Revueltosaurus and aetosaurs: scapula/coracoid, humerus, squamosal and armor design. You can see (Fig. 1) that despite being twice the size, Revueltosaurus has more gracile girdles and limbs and larger hands and feet than Aetosaurus. And the skull has a distinctly different shape in nearly all regards, including the squamosal. Even so…

An herbivorous rauisuchid, with several aetosaur and turtle-like traits.
On Revueltosaurus, the naris is rather unique. The lateral processes of the premaxilla have become more robust, reducing the size of the naris and moving them to an anterior position.  Revueltosaurus shares these traits with Fugusuchus.

Figure 2. Revueltosaurus pelves compared to Aetosaurus and Postosuchus. Red arrows point to limit of femoral head. Blue arrows point to acetabular shelf that roofs over the femur in rauisuchids.

Figure 2. Revueltosaurus pelves compared to Aetosaurus and Postosuchus. Red arrows point to limit of femoral head. Blue arrows point to acetabular shelf that roofs over the femur in rauisuchids. Revueltosaurus is a small slow quadrupedal plant eater, so it doesn’t have the long booted pelvis of Postosuchus. But note the similarity of the broad ischium to Aetosaurus!  Wm. Parker tells me, “It’s the plesiomorphic archosauriform condition with the very short anterior process. Lacks the deep supracetabular buttress found in rauisuchids. It actually looks like a juvenile aetosaur and it is difficult to tell them apart.” Schoch reports the aetosaur oblique posterior ridge is unlike the supraacetabular ‘boss’ of rauisuchids.

The pelvis should settle the argument
But it doesn’t. The pelvis of Revueltosaurus appears to bear a acetabular boss beneath which the femur articulates and supports. In aetosaurs the pelvis has a simpler shape without the boss. In aetosaurs the pelvis is wider at the top, which provides a broad platform for the armor, and angles inward ventrally. We don’t have a pelvis and hind limb for Fugusuchus, but Euparkeria is not far off. So is Gargainia. Both have similar elements.Here again, the different nesting sites appear to be based on employing macro-traits or micro-traits. This is a problem I have no solution for at present.

Figure 2. Revueltosaurus

Figure 2. Revueltosaurus

 

References
Hunt AP 1989. A new ornithischian dinosaur from the Bull Canyon Formation (Upper Triassic) of east-central New Mexico. In Lucas, S. G. and A. P. Hunt (Eds.), Dawn of the age of dinosaurs in the American Southwest 355–358.
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.
Parker WG., et al. 2005
. The Pseudosuchian Revueltosaurus callenderi and its implications for the diversity of early ornithischian dinosaurs. In Proceedings of the Royal Society London B 272(1566):963–969.

wiki/Revueltosaurus

Revueltosaurus in higher resolution

An online photo of Revueltosaurus (Fig. 1) adds details and clarifies problems. There is also a Vimeo video here featuring paleontologist, William Parker, who authors the Chinleana blogsite. He also discovered 11 skeletons of Revueltosaurus from one site with two that are nearly complete or complete. From that data the complete skeleton (Fig. 1) has been recreated.

Figure 1. Revueltosaurus skull from online source (link above) color coded to bone. Above, the aetosaur, Stagonolepis, to which Nesbitt and Parker nest Revueltosaurus. In contrast, the large reptile tree nests Fugusuchus with Revueltosaurus as a derived herbivorous erythrosuchid.

Figure 1. Revueltosaurus skull from online source (link above) color coded to bone. Above, the aetosaur, Stagonolepis, to which Nesbitt and Parker nest Revueltosaurus. In contrast, the large reptile tree nests Fugusuchus with Revueltosaurus as a derived herbivorous erythrosuchid.

With this data, Nesbitt (2011) nested Revueltosaurus at the base of the Aetosauria with Aetosaurus and Stagonolepis.

In counterpoint,
The large reptile tree, employing a different character list, nested Revueltosaurus with Postosuchus, as a derived, smaller, somewhat turtle-ized rauisuchid.

We’ll look at the pros and cons of both analyses tomorrow.

References
Hunt AP 1989. A new ornithischian dinosaur from the Bull Canyon Formation (Upper Triassic) of east-central New Mexico. In Lucas, S. G. and A. P. Hunt (Eds.), Dawn of the age of dinosaurs in the American Southwest 355–358.
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.
Parker WG., et al. 2005
. The Pseudosuchian Revueltosaurus callenderi and its implications for the diversity of early ornithischian dinosaurs. In Proceedings of the Royal Society London B 272(1566):963–969.

wiki/Revueltosaurus

Luperosuchus: an erythrosuchid, not a rauisuchian

Luperosuchus fractus (Romer 1972, PULR 04) was considered a indistinct pseudosuchian originally and later a rauisuchian by Desojo and Arcucci (2009). The large reptile tree recovers it as an erythrosuchid and a sister to Shansisuchus, which had an even larger subnarial fenestra. Earlier we looked at the two Shansisuchus specimens, noting that the referred specimen was much larger than the holotype with a distinct morphology, more like Luperosuchus.

Figure 1. Luperosuchus restored based on Romer 1971. Above: original drawing by Romer. Below tracing based on photo in Romer 1971, specimen PULR 04. At right is referred specimen PULR 057. Although related, the referred specimen strikes me as generically different with the low placement of the naris and large postorbital.

Figure 1. Luperosuchus restored based on Romer 1971. Above: original drawing by Romer. Below tracing based on photo in Romer 1971, specimen PULR 04. Extension of the qj and a deeper max gives it more of a erythrosuchid look. At right is referred specimen PULR 057. Although related, the referred specimen strikes me as generically different with the low placement of the naris and large postorbital. Analysis on PULR 057 has not been done.

The reconstruction by Desojo and Arcucci (2009, Fig. 1, above) assumes a short quadratojugal, but a longer qj (Fig. 1, below) matches sister taxa.

This one is probably a rauisuchid
Another much smaller specimen (PULR 057, Fig. 1) was referred to Luperosuchus. That seems doubtful based on the lower placement of the naris, the straighter rostral profile, the larger antorbital fenestra, the deeper pmx/mx notch and the more robust postorbital. These traits appear to lead to Ticinosuchus and the aetosaurs as other archosauriformes retain a high naris. A second possibility leads toward the euparkeriid Osmolskina. A phylogenetic analysis was not attempted due to the small number of traits shown.

References
Desojo JB and Arcucci AB 2009. New material of Luperosuchus fractus (Archosauria: Crurotarsi) from the Middle Triassic of Argentina: the earliest known South American ‘Rauisuchian’. Journal of Vertebrate Paleontology 29(4): 1311-1315. 
Romer AS 1971. The Chañares (Argentina) Triassic reptile fauna. VIII. A fragmentary skull of a large thecodont, Luperosuchus fractus. Breviora 373:1-8.

Short note: ReptileEvolution.com has just passed a million hits for this year. Between 4.2 and 5.7 thousand unique visitors access the site every month.

What is Asperoris?

A recent online paper by Nesbitt et al. 2013 introduces us to a new Middle Triassic East African archosauriform, Asperoris mnyama (NHMUK PV R36615), known from several 3D skull pieces (Fig. 1).

Figure 1. Asperoris skull reconstruction. Turns out it's just an ordinary rauisuchid linking Vjushkovia to more derived forms.

Figure 1. Asperoris skull reconstruction. Turns out it’s just an ordinary rauisuchid linking Vjushkovia to more derived forms. Tooth length is pure guesswork.

Nesbitt et al. was unable to resolve what Asperoris was (Fig. 2). So they considered it a “non-archosaurian archosauriform” (incerta sedis). Unfortunately they included rauisuchids within the Archosauria in their analysis AND they included several unrelated taxa: a lepidosauriform (Mesosuchus), a thalattosaur (Vancleavea) and two pararchosauriform supragenera (Proterochampsidae and Phytosauria). That didn’t leave too many related taxa to compare Asperoris to. And they missed the most obvious candidates, like Vjushkovia (Fig. 3). That’s why we turn to the large reptile tree (Fig. 2, subset here) to find out where Asperoris might nest.

Figure 2. The confused nesting of Asperoris according to Nesbitt et al. 2013 (above) and the exact nesting according to the large reptile tree (below).

Figure 2. The confused nesting of Asperoris according to Nesbitt et al. 2013 (above) and the exact nesting according to the large reptile tree (below) as as sister to Vjushkovia.

The large reptile tree data analysis started with a reconstruction of Asperoris (Fig.1), which enabled the employment of several traits not readily apparent from the separated bones. The results nested Asperoris within the Rauisuchidae as the sister to Vjushkovia,  a taxon not included in the Nesbitt (2011) study on archosaurs.

The Nesbitt et al. 21013 definition of Archosauria is not confirmed here.
Nesbitt et al. report, “Archosauria, the crown clade that includes living birds and crocodilians as well as extinct dinosaurs, pterosaurs and pseudosuchians (stem-crocodilians), is one of the most successful evolutionary radiations in the history of vertebrate life on land.” In the large reptile tree, Archosauria includes just crocs and dinos (including birds). Pterosaurs nest with tritosaur lizards. Pseudosuchians, it turns out, are diphyletic with parasuchians and proterochampsids nesting with choristoderes, on a separate branch from the rest of the traditional archosauriforms.

Not far from Vjushkovia
Asperoris shared many skull traits with Vjushkovia and was about the same size. Like Vjushkovia, Asperoris also lacked an antorbital fossa on the maxilla. According to Nesbitt et al. “Asperoris mnyama differs from all known archosauriforms in having highly sculptured cranial elements including the premaxilla, maxilla, nasal, prefrontal, frontal, postfrontal, and parietal, and in having a highly sculptured, dorsoventrally deep orbital margin of the frontal.” This may be a distinct trait indeed.

Vjushkovia.

Figure 3. Vjushkovia had 3 premaxillary teeth and a descending jugal, but otherwise would have been similar to Asperoris in shape and size.

So no great shakes. 
Asperoris was about the size of Vjushkovia and Batrachotomus, so smaller than some rauisuchids. It’s not a key taxon providing new insight into relationships.

Sadly,
having access to data that showed pterosaurs and Vancleavea should not be included in archosauriform studies was not followed by any testing of these oddly nested taxa. Rather Nesbitt et al. (2013) held on to their old traditions — which is a major problem with their study.

Once again, I have not seen the original material (nothing here changes in interpretation anyway), but I do have a larger gamut study from which more accurate and confident nestings can be made. This is available to anyone who wishes to use it. Moreover, the taxonomic clades that result can provide guidance for future inclusion sets. At least they should be tested.

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 SJ, Butler RJ, Gower DJ 2013. A New Archosauriform (Reptilia: Diapsida) from the Manda Beds (Middle Triassic) of Southwestern Tanzania. PLoS ONE 8(9): e72753. doi:10.1371/journal.pone.0072753

NHMUK, The Natural History Museum, London, United Kingdom;

Reconstructing the hand of Ticinosuchus

Sometimes fossils are wonderfully preserved
and fully articulated. Sometimes they are wonderfully preserved but woefully disarticulated. At such times, most of the bones can be fit together with ease, but the bones of the fingers and toes can be vexing.

Figure 1. Ticinosuchus forelimbs. Note the scattered manual elements here reconstructed to create PILs and match sister taxa patterns.

Figure 1. Ticinosuchus forelimbs. Note the scattered manual elements here reconstructed to create PILs and match sister taxa patterns. Yellow is the radius. Pink is the ulna. Metatarsal 3 is the most robust based on sister taxa. The phalangeal pattern is 2-3-4-5-4.

Case in point: Ticinosuchus
An important taxon in the evolution of crocs and dinosaurs and other Triassic oddities is the basal rauisuchian, Ticinosuchus. It had departed from the rauisuchian ancestors so much that it is basal to the armored herbivorous aetosaurs of the Late Triassic. Most of the elements of both manus of the Ticinosuchus are present, but scattered. That doesn’t mean they’re impossible to put back together again.

Trace the parts.
Move the parts into a logical pattern (thick with thick, thin with thin, gradually tapering digits, phylogenetic bracketing patterns) then test your results to see if PILs (parallel interphalangeal lines) are produced. When all that happens, you can have high confidence in a correct solution.

Figure 2. Ticinosuchus overall, hand, foot and skull.

Figure 2. Ticinosuchus overall, hand, foot and skull. The hand is presented as originally interpreted by Krebs and by a new reconstruction based on the tracing in figure 1 and phylogenetic bracketing.

This is a long-armed quadrupedal taxon with long (longer than each metacarpal). Metacarpal 3 was the most robust. Metacarpal 5 was extremely short. Digits 3 and 4 were subequal. Digit 1 was the shortest digit, but digit 5 had smaller phalanges. Where known, sister taxa share most of these traits.

Earlier here, here and here we put the manus of an early archosauriform together.

References
Krebs B 1965. Ticinosuchus ferox nov. gen. nov. sp. Ein neuer Pseudosuchier aus der Trias des Monte San Giorgio. Schweizerische Palaontologische Abhandlungen 81:1-140.
Lautenschlager S and Desojo JB 2011. Reassessment of the Middle Triassic rauisuchian archosaurs Ticinosuchus ferox and Stagonosuchus nyassicus. Paläontologische Zeitschrift Online First DOI: 10.1007/s12542-011-0105-1

wiki/Ticinosuchus