Müller et al. discuss Lagerpeton ‘sisters’ without Tropidosuchus

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

More PVL 4597 post-crania

Lecuona et al. 2017 
redescribe the post-crania of the basal archosaur and basal Crocodylomorph (in the large reptile tree = LRT), Gracilisuchus. They used six specimens and recovered them as basal Suchia (= aetosaurs, rauisuchians and crocodylomorphs). The LRT does not recover these three monophyletic clades in one larger monophyletic clade. So the LRT does not support the ‘Suchia’ as a clade.

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

Figure 1. The PVL 4597 specimen attributed to Gracilisuchus by Lecuona et al. 2017, but nesting at the base of the Dinosauria in the LRT. The pelvis of Herrerasaurus is shown on frame 2 of this simple animation. 

Unfortunately
Lecuona et al. excluded from their analysis several taxa that nest close to Gracilisuchus in the large reptile tree. These include Saltopus and Scleromochlus, which nest as sisters to Gracilisuchus in the LRT. Lewisuchus is mentioned in the text and combined as a chimaera with Pseudolagosuchus, but I don’t see the combo in the published trees. Their cladogram includes several suprageneric taxa (always to be avoided) including ‘Pterosauromorpha’ (= pterosaurs + Scleromochlus, not recovered as a clade in the LRT as a clade and how would one score such an internally varied taxon??).

Lecuona et al. nest their purported Gracilisuchus specimens together.
By contrast the LRT nests PVL 4597 at the base of the Dinosauria.

Fortunately 
the authors provide more data on the provisional dinosaur outgroup taxon, PVL 4597, so far based on hind limb traits only (Lecuona and Desojo 2011. The preserved skull in the specimen has not yet been published.

As in the LRT
the authors also find a close relationship between Turfanosuchus and Gracilisuchus. Unlike the LRT, they nest Yonghesuchus between them. The LRT nests it as a sister to Dromicosuchus.

It’s not common for a specimen to be published in bits and pieces
The original pelvis data came out 6 years ago. The new data for PVL 4597 (Fig. 1) still lacks the skull, which will be published in the future. I have written to Dr. Lecuona encouraging an expansion of the taxon list. I also hope the suprageneric taxa will be broken up into lists of genera.

References
Lecuona A and Desojo, JB 2011. Hind limb osteology of Gracilisuchus stipanicicorum (Archosauria: Pseudosuchia). Earth and Environmental Science Transactions of the Royal Society of Edinburgh 102 (2): 105–128.
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 zlx011 1–40.

Pseudhesperosuchus fossil photos

Earlier I used
Greg Paul and José Bonaparte drawings of the basal bipedal croc Pseudhesperosuchus Bonaparted 1969) for data on this taxon. The specimen has some traits that lead toward the secondarily quadrupedal Trialestes. Together they are part of a clade that is closer to basal dinosaurs than traditional taxa paleontologists have been working with.

The drawings were great,
but I wondered what the real material looked like…and more importantly, what was real and what was not.

A recent request to
the curators at Miguel Lillo in Argentina was honored with a set of emailed jpegs from their museum drawers (Fig.1), for which I am very grateful. These were traced in line and color and reassembled with just a few unidentified parts left over (Fig. 2).

Figure 1. GIF movie of the skull of Pseudhesperosuchus showing the original drawing, the fossil and DGS tracings of the bones.

Figure 1. GIF movie of the skull of Pseudhesperosuchus showing the original drawing, the fossil and DGS tracings of the bones.

Pseudhesperosuchus jachaleri (Bonaparte 1969 Norian, Late Triassic ~210mya, ~1 m in length, was derived from a sister to Junggarsuchus and  Lewisuchus and was at the base of a clade that included Trialestes on one branch and the Dinosauria on the other branch.

Figue 1. A new reconstruction of the basal bipedal croc, Pseudhesperosuchus based on fossil tracings. Some original drawings pepper this image. Note the interclavicle, missing in dinosaurs and the very small ilium, only wide enough for two sacrals. The posterior dorsals are deeper than the anterior ones.

Figue 2. A new reconstruction of the basal bipedal croc, Click to enlarge. Pseudhesperosuchus based on fossil tracings. Some original drawings pepper this image. Note the interclavicle, missing in dinosaurs and the very small ilium, only wide enough for two sacrals. The posterior dorsals are deeper than the anterior ones.

Much larger and distinct from Lewisuchus,
the skull of Pseudhesperosuchus had a smaller antorbital fenestra, an arched lateral temporal fenestra, a deeper maxilla and a large mandibular fenestra. The seven cervicals were attended by robust ribs.

The scapula and coracoid were each rather slender and elongated. An straight interclavicle was present. The forelimbs were long and slender. The radiale and ulnare were elongated, a croc trait. Only three metacarpals and no digits are known.

The ilium was relatively small, but probably longer than tall and not perforated. The femur remained longer than the tibia. The tarsus, if that astragalus is identified correctly, included a simple hinge ankle joint. Only two conjoined partial metatarsals are known.

There is a small box
full of little sometimes interconnected squares among the Pseudhesperosuchus material (Fig. 2, aqua colored). I’m guessing that those are osteoderms, and if so, were probably located along the back. These would have helped keep that elevated backbone from sagging in this new biped.

The improvements in the Pseudhesperosuchus data
changed a few scores, but did no change the tree topology. The large reptile tree (LRT) can be seen here.

It’s good to see what Pseudhesperosuchyus really looked like,
— or at least get a little closer to that distant ideal. Size-wise and morphologically, this largely complete specimen is closer to the basal dinosaur outgroup than any other currently included in the LRT. And yet it is also distinctly different as it shares several traits with Trialestes unknown in any dinosaur. As a denizen of the Late Triassic, Pseudhesperosuchus represents a radiation that occurred tens of millions of years earlier, probably in the Middle Triassic. None of this clade survived into the Jurassic, as far as we know.

References
Bonaparte JF 1969. Dos nuevos “faunas” de reptiles triásicos de Argentina. Gondwana Stratigraphy. Paris: UNESCO. pp. 283–306.

The forgotten clade: the REAL proximal ancestors to Dinosauria

Ignored by Baron et al. 2017, and everybody else
the Junggarsuchus clade (including Pseudhesperosuchus, Carnufex and Trialestes in order of increasing quadrupedality, Figs. 1–4) nests as the proximal ancestors to Herrerasaurus (Fig. 1) and the rest of the Dinosauria (Fig. 5) in the large reptile tree (LRT). That cladogram tests a wider gamut of taxa in greater detail than any other reptile cladogram ever published, attempting to not overlook anything. The Junggarsuchia is a sister clade to the Crocodylomorpha with both arising from a taxon near Lewisuchus (Fig. 1). Traditional paleontology (see Wikipedia) nests this largely ignored clade with the sphenosuchian crocodylomorphs (Fig. 4)… and for two good reasons!

Figure 1. Members of the Junggarsuchus clade were derived from a sister to the basal crocodylomorph, Lewisuchus and produced one line that includes Pseudhesperosuchus and Trialestes. The other line produced dinosaurs. These taxa are shown to scale. Note the evolution from a bipedal configuration to a quadrupedal stance.

Figure 1. Members of the Junggarsuchus clade were derived from a sister to the basal crocodylomorph, Lewisuchus and produced one line that includes Pseudhesperosuchus and Trialestes. The other line produced dinosaurs. These taxa are shown to scale. Note the evolution from a bipedal configuration to a quadrupedal stance.

One: Paleontologists never seem to include Dinosauria
in their smaller gamut croc analyses because they’re looking at crocs!~. So once again, taxon exclusion is holding some workers back from seeing ‘the big picture’. ReptileEvolution.com and the blog you are currently reading is all about examining ‘the big picture.’

Figure 2. Skulls of the Junggarsuchus clade not to scale. Herrerasaurus is the basalmost dinosaur.

Figure 2. Skulls of the Junggarsuchus clade not to scale. Herrerasaurus is the basalmost dinosaur, closely related to Junggarsuchus.

Two: Junggarsuchians ALSO have elongate proximal wrist bones
Elongate proximal carpals are found in both sphenosuchian crocs and derived members of the Junggarsuchus clade. Paleontolgists wrongly assumed such odd wrist bones were homologous. It’s an easy mistake to make. However, the LRT makes clear that intervening taxa, including Junggarsuchus, do not have elongate wrist bones.

Among taxa that preserve the manus,
(Fig. 3) it is Junggarsuchus that nests closest to Herrerasaurus and the Dinosauria.

Figure 3. Hands of Lewisuchus, Herrerasaurus, Junggarsuchus, Pseudhesperosuchus and Trialestes. The proximal carpals (radiale and ulnare) were elongate by convergence with a line of crocodylomorphs. This has confused paleontologists and mentally removed them from possible ancestry to the Dinosauria. Note the very short proximal carpals in Junggarsuchus.

Figure 3. Hands of Lewisuchus, Herrerasaurus, Junggarsuchus, Pseudhesperosuchus and Trialestes. The proximal carpals (radiale and ulnare) were elongate by convergence with a line of crocodylomorphs. This has confused paleontologists and mentally removed them from possible ancestry to the Dinosauria. Note the very short proximal carpals in Junggarsuchus.

Like the basal members of the Crocodylomorpha
the Junggarsuchus clade (the Prodinosauria here) transition from bipedal basal members to quadrupedal derived members, with the longest forelimbs belonging to the most derived member, Trialestes (Fig. 3). Distinct from the others and contra the original interpretation, I think Trialestes may have had a larger ulnare than radiale, to match its larger ulna.

Figure 4. Crocodylomorph manus and carpus samples including Terrestrisuchus, Erpetosuchus, Hesperosuchus and Dibothrosuchus along with Scleromochlus documenting the elongate radiale and ulnare on derived taxa. Ticinosuchus is the closest example of an ancestral/plesiomorphic manus in the LRT.

Figure 4. Crocodylomorph manus and carpus samples including Terrestrisuchus, Erpetosuchus, Hesperosuchus and Dibothrosuchus along with Scleromochlus documenting the elongate radiale and ulnare on derived taxa. Ticinosuchus is the closest example of an ancestral/plesiomorphic manus in the LRT.

Let’s not forget
PVL 4597 (Fig. 6) which was mistakenly considered a specimen of Gracilisuchus by (Lecuona and Desojo 2011), but under phylogenetic analysis in the LRT, still nests as the proximal outgroup to Herrerasaurus. It is tiny specimen, supporting the hypothesis of phylogenetic miniaturization at clade origin. And it retains a small proximally oriented calcaneal tuber, as found in other Junggarsuchians.

Figure 1. Subset of the LRT focusing on the Archosauria (Crocodylomorpha + Dinosauria and kin). Gray areas document specimens with elongate proximal carpals (radiale and ulnare).

Figure 5. Subset of the LRT focusing on the Archosauria (Crocodylomorpha + Dinosauria and kin). Gray areas document specimens with elongate proximal carpals (radiale and ulnare).

We looked at
phylogenetic miniaturization at the origin of several pterosaur clades. Well, it happens here too, at the base of the Dinosauria (Fig. 1) with PVL 4597 (Fig. 6), easily overlooked, easily mistaken for something else.

One should not ‘choose’ outgroup taxa
based on paradigm, tradition, guessing, convenience or opinion. Rather outgroup taxa should ‘choose themselves’ based on rigorous testing of a large gamut of outgroup candidates in phylogenetic analysis. To minimize selection bias, the LRT provides 858 outgroup taxa the opportunity to nest close to dinosaurs.

Figure 6. The closest known taxa to the Dinosauria, PVL 4597, is a tiny taxon (phylogenetic miniaturization) with erect hind limbs, a large and deep pelvis and a tiny calcaneal tuber.

Figure 6. The closest known taxa to the Dinosauria, PVL 4597, is a tiny taxon (phylogenetic miniaturization) with erect hind limbs, a large and deep pelvis and a tiny calcaneal tuber.

 

References
Baron MG, Norman DB, Barrett PM 2017. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 543:501–506.
Bonaparte JF 1969. 
Dos nuevos “faunas” de reptiles triásicos de Argentina. Gondwana Stratigraphy. Paris: UNESCO. pp. 283–306.
Butler RJ. et al. 2014. New clade of enigmatic early archosaurs yields insights into early pseudosuchian phylogeny and the biogeography of the archosaur radiation. BMC Evol. Biol. 14, 128.
Clark JM et al. 2000. A new specimen of Hesperosuchus agilis from the Upper Triassic of New Mexico and the interrelationships of basal crocodylomorph archosaurs. Journal of Vertebrate Paleontology 20 (4): 683–704.
doi:10.1671/0272-4634(2000)020[0683:ANSOHA]2.0.CO;2.
Clark JM, Xu X, Forster CA and Wang Y 2004. A Middle Jurassic ‘sphenosuchian’ from China and the origin of the crocodilian skull. Nature 430:1021-1024.
Lecuona A and Desojo, JB 2011. Hind limb osteology of Gracilisuchus stipanicicorum(Archosauria: Pseudosuchia). Earth and Environmental Science Transactions of the Royal Society of Edinburgh 102 (2): 105–128.
Nesbitt SJ 2011. The early evolution of archosaurs: relationship and the origin ofmajor clades. Bull. Amer. Mus. Nat. Hist. 352, 1–292.
Novas FE 1994. New information on the systematics and postcranial skeleton of Herrerasaurus ischigualastensis (Theropoda: Herrerasauridae) from the Ischigualasto
Reig OA 1963. La presencia de dinosaurios saurisquios en los “Estratos de Ischigualasto” (Mesotriásico Superior) de las provincias de San Juan y La Rioja (República Argentina). Ameghiniana 3: 3-20.
Sereno PC and Novas FE 1993. The skull and neck of the basal theropod Herrerasaurusischigualastensis. Journal of Vertebrate Paleontology 13: 451-476. doi:10.1080/02724634.1994.10011525.
Zanno LE, Drymala S, Nesbitt SJ and Schneider VP 2015. Early Crocodylomorph increases top tier predator diversity during rise of dinosaurs. Scientific Reports 5:9276 DOI: 10.1038/srep09276.

wiki/Pseudhesperosuchus
wiki/Junggarsuchus
wiki/Carnufex
wiki/Herrerasaurus
wiki/Sanjuansaurus

 

Teleocrater: a sister to Yarasuchus, not the earliest bird-line archosaur.

Unfortunately
another paper that was improperly vetted (refereed). I heard about this one on NPR when co-author Richard Butler was interviewed by the BBC.

Nesbitt et al. 2017
report: The relationship between dinosaurs and other reptiles is well established (1–4,) but the sequence of acquisition of dinosaurian features has been obscured by the scarcity of fossils with transitional morphologies.”

We’re in trouble from the opening salvo.
The large reptile tree (LRT) does not recover the same tree topology as these authors hypothesize (Fig. 1). And the sequence of dinosaurian features is not obscured in the LRT. There are plenty of fossils with transitional morphologies. Unfortunately, these authors either chose to ignore them or scored them haphazardly. Based on the theory that evolution happens with small changes the Nesbitt et al. tree topology (Fig. 1) is completely bonkers, adding unrelated taxa while excluding pertinent sisters to Teleocrater (here labeled under its new clade, Aphanosauria).

Figure 1. Aphanosauria according to Nesbitt et al. 2017. Two of these clades are unrelated to archosaurs. Marasuchus IS a dinosaur. Silesaurus is a poposaur more distantly related to dinos than crocs.

Figure 1. Aphanosauria according to Nesbitt et al. 2017. Two of these clades are unrelated to archosaurs. Marasuchus IS a dinosaur. Silesaurus is a poposaur more distantly related to dinos than crocs. Where are the crocs?

Nesbitt et al. report:
“H
ere we describe one of the stratigraphically lowest and phylogenetically earliest members of the avian stem lineage (Avemetatarsalia), Teleocrater rhadinus gen. et sp. nov., from the Middle Triassic epoch.” There is no such thing as an avian stem lineage. Avemetarsalia includes pterosaurs and dinosaurs, so it is a junior synonym for Reptilia in the LRT. The closest ancestors to dinosaurs were bipedal basal crocodylomorphs in the LRT. I don’t see them in figure 1. 
Teleocrater holotype.
NHMUK (N
atural History Museum, London, UK) PV 
R6795, a disassociated skeleton of one individual, including: cervical, trunk, and caudal vertebrae, partial pectoral and pelvic girdles, partial forelimb and hind limbs. 
Referred material.
Elements f
ound near the holotype, but from other 
individuals, which represent most of the skeleton and that are derived from a paucispecific bone bed containing at least three individuals.
Figure 2. The chimaera created by several specimens attributed to Telocrater. Even if all these piece do fit together like Nesbitt et al. indicate, Telocrater is closer to Yarasuchus and Ticinosuchus than it is to the last common ancestor of Archosauria.

Figure 2. The chimaera created by several specimens attributed to Teleocrater. Even if all these piece do fit together like Nesbitt et al. indicate, Teleocrater is closer to Yarasuchus and Ticinosuchus than it is to the last common ancestor of Archosauria. See figure 3.

The specimens that produced this reconstruction (Fig. 2)
are all associated. So there is great confidence that all of the bones are conspecific. The problem, once again, is taxon exclusion, and maybe a large dose of bad scoring (see below)

Figure 3. Telocrater to scale compared with likely sister taxa among the Ticinosuchidae in the LRT. Note the resemblance of the Telocerater maxilla to that of these sister taxa.

Figure 3. Teleocrater to scale compared with likely sister taxa among the Ticinosuchidae in the LRT. Note the resemblance of the Teleocerater maxilla to that of these sister taxa.

Oddly
the authors report that “Osteoderms are not preserved and were probably absent.” And yet their reconstruction (Fig. 2) has osteoderms in the black outline. What bias is present here?

Oddly
the authors report, Our phylogenetic analyses recovered Teleocrater in a clade containing Yarasuchus, Dongusuchus and Spondylosoma.” And yet they did not include Yarasuchus in their phylogenetic figure (Fig. 1). The latter two are know from scraps. Yarasuchus (Fig. 3) is much more complete. 

Problems with the Nesbitt et al. 2017 cladogram

  1. The outgroup for Prolacerta + Archosauriformes (Proterosuchus) is the unrelated lepidosaur, Mesosuchus.
  2. The unrelated thalattosaur, Vancleavea, nests between Erythrosuchus and the unrelated chanaresuchid, Tropidosuchus. None of these taxa even look alike!
  3. The Yarasuchus clade, and before it the Parasuchus clade gives rise to the pterosaurs DimorphodonEudimorphodon and another chanaresuchid, Lagerpeton, both purportedly in the lineage of dinosaurs. These are all actors pretending to be relatives. How is this possible that Nesbitt et al, and the referees and editors at Nature are not raising objections to this? This is total madness at the highest levels.

Need I go on???
Why is Teleocrater big news? Because the authors positioned it as an ancestor to dinosaurs. It may be, but it is buried deep, deep, deep in the lineage. Why was the relationship with Yarasuchus buried? You know why… it’s not as ‘sexy’ to the press.

Nesbitt et al. report,Aphanosauria…is the sister taxon of Ornithodira (pterosaurs and birds) and shortens the ghost lineage inferred at the base of Avemetatarsalia.” Surprised to see they didn’t say, ‘pterosaurs and Tyrannosaurus rex.’ 

Folks, it’s all showmanship.
I’m sure the authors have all toasted their new paper in Nature by now. I hate seeing the subject of evolution twisted, torn and laid bare like this.

The real importance of Teleocrater
is its basal position in a clade I earlier called Ticinosuchidae, arising from basal rauisuchians, like Vjushkovia, giving rise to a wide variety of taxa like Aetosaurus and Arizonasaurus) while also giving rise to Decuriasuchus, which gave rise to poposaurs, like Turfanosuchus, and archosaurs, thus ultimately including dinosaurs.

References
Nesbitt SJ et al. (10 co-authors) 2017. The earliest bird-line archosaurs and the assemblof the dinosaur body plan. Nature doi:10.1038/nature22037. (online pdf)

1. Benton, M. J. & Clark, J. M. in The Phylogeny and Classification of the Tetrapods.
Volume 1: Amphibians, Reptiles, Birds. Systematics Association Special Volume
35A (ed. Benton, M. J.) 295–338 (Clarendon, 1988).
2. Gauthier, J. Saurischian monophyly and the origin of birds. Mem. Calif. Acad.
Sci. 8, 1–55 (1986).
3. Sereno, P. C. Basal archosaurs: phylogenetic relationships and functional
implications. Soc. Vertebr. Paleontol. Mem. 2, 1–53 (1991).
4. Sereno, P. C. The evolution of dinosaurs. Science 284, 2137–2147 (1999).

The cervical/dorsal transition in Herrerasaurus

Figure 1. Lewisuchus cervical/dorsal transition at top photo and the same for Herrerasaurus drawings, including a foreword shift of the pectoral girdle in a 2-frame GIF movie. The cervical ribs are imagined.

Figure 1. Lewisuchus cervical/dorsal transition at top photo and the same for Herrerasaurus drawings, including a foreword shift of the pectoral girdle in a 2-frame GIF movie. The cervical ribs are imagined in the drawing. See text for details. Drawings from Novas and Sereno 1994.

In their report on the basal dinosaur Herrerasaurus,
Sereno and Novas 1993 reported, “The cervical column (Fig. 1) was preserved in articulation with the skull. The anterior cervical vertebrae are better preserved than the posterior cervical vertebrae, and nearly all the ribs are lacking.”

“Because the cervical-dorsal transition in vertebrae or ribs is not preserved, we regard the first ten presacral vertebrae as cervical vertebrae, based on the condition in other basal dinosaurians.”

Despite their assessment, 
Novas and Sereno appear to have reconstructed Herrerasaurus with no more than six or possibly seven cervicals (Fig. 1, original).  With phylogenetic scoring at issue, a deeper look was warranted.

Novas and Sereno 1993 considered Herrerasaurus
a member of the ‘Ornithodira’ thus related to pterosaurs and Lagerpeton. That hypothesis is not supported by the present study.

By contrast,
in the large reptile tree (LRT) Herrerasaurus arises from another list of taxa, including Junggarsuchus, Pseudhesperosuchus, LewisuchusTurfanosuchus and further distantly Decuriasuchus. Bittencourt et al. 2014 identify seven cervicals in Lewisuchus (Fig. 1) with the eighth having ribs descending into the torso. Seven is a number common to crocodylomorpha* and Lewisuchus nests at its base. Turfanosuchus and Decuriasuchus each have eight cervicals, a plesiomorphic number going back at least to basal archosauriformes, like Proterosuchus and to basal diapsids, like Petrolacosaurus.

Based on available data,
Herrerasaurus had but seven cervicals as a basal dinosaur. Based on data from Tawa, Marasuchus, Eodromaeus and Eoraptor, all slightly more derived basal dinosaurs had 9 or 10.

* Among Crocodylomorpha, Scleromochlus has six cervicals, Gracilisuchus, Litargoschus and Terrerstrisuchus have eight, as do modern crocs and their relatives by convergence. Intervening taxa often have seven.

References
Bittencourt JS, Arcucci AB, Maricano CA and Langer MC 2014. Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chañares Formation, Argentina) its inclusivity, and relationships amongst early dinosauromorphs. Journal of Systematic Palaeontology. Published online: 31 Mar 201. DOI:10.1080/14772019.2013.878758
Nesbitt SJ. et al. 2010. Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira. Nature 464(7285):95-8
Novas FE 1994. New information on the systematics and postcranial skeleton of Herrerasaurus ischigualastensis (Theropoda: Herrerasauridae) from the Ischigualasto Romer AS 1972. The Chañares (Argentina) Triassic reptile fauna; XIV, Lewisuchusadmixtus, gen. et sp. nov., a further thecodont from the Chañares beds. Breviora 390:1-13
Sereno PC and Novas FE 1993. The skull and neck of the basal theropod Herrerasaurusischigualastensis. Journal of Vertebrate Paleontology 13: 451-476. doi:10.1080/02724634.1994.10011525.

wiki/Lewisuchus
wiki/Herrerasaurus