Arizonasaurus babbitti (Welles 1947, Nesbitt 2003) Middle Triassic ~240mya, was derived from a sister to Vjushkovia. Arizonasaurus was a sister to Yarasuchus within the Ticinosuchidae, a clade that represents a mixed bag of morphologies, meaning it no doubt had a more ancient last common ancestor.

Distinct from Vjushkovia, Arizonasaurus probably had a longer premaxilla (but this is a guess based on the related Qianosuchus). The anterior maxilla was deeply convex. The temporal and cheek elements were gracile.

The cervical centra were smaller, but the neural spines were very tall. The dorsal neural spines were taller still, creating a Spinosaurus-like sail.

The scapula was much smaller, almost petite, suggesting the forelimbs were likewise small creating a possible bipedal configuration. The hyper-elongated pubis was nearly matched by an equally gracile ischium that descended nearly as far. This trait also leads to the idea of a possible bipedal configuration, as in dinosaurs, if the femora were as long as pubis or longer, as in sister taxa.

The high sail was decorative and added to the surface area of Arizonasaurus, creating a larger solar collector/heat radiator for faster and more precise internal temperature regulation and greater stiffening of the dorsal spine, perhaps for elevating the forelimbs.

Xilousuchus sapingensis   Wu, 1981 Nesbitt et al. 2010) was originally considered a proterosuchid, then associated with Arizonasaurus. Here (Fig. 1) those long cervicals match well with Yarasuchus, a sister to Qianosuchus and Arizonasaurus.

Nesbitt et al. (2010) considered this a poposaur archosaur, thus making this taxon the unequivocally oldest known member of Archosauria. Here it nests outside the Archosauria.

Ctenosauriscus koeneni (von Huene 1902, originally Ctenosaurus) Olenekian, latest Early Triassic, was originally considered a type of pelycosaur close to Dimetrodon that had somehow survived into the Triassic. Further discoveries and studies placed it with contemporary rauisuchians like Arizonasaurus. But was it more closely related to the dinosaur, Lotosaurus? I can't tell with the present data. Distinct from Lotosaurus, the sail portion of the vertebrae originated further anteriorly, over the mid cervicals and was overall much taller, but then it lived tens of millions of years later.

A recent online paper by Butler et al. (2011) reports: "Both analyses recover a monophyletic Ctenosauriscidae that excludes Lotosaurus, but includes Arizonasaurus, Xilousuchus, Ctenosauriscus, the Waldhaus taxon, and Hypselorhachis. The most consistent characters supportining Ctenosauriscidae are the great elongation of the dorsal neural spines, and the fact that these elongated neural spines are curved along their length.

The skulls of several rausuchians beginning with Euparkeria. Several lineages produced classic rausuchians like Prestosuchus and Saurosuchus, a separate lineage produced Postosuchus, another produced Decuriasuchus followed by archosaurs, and finally Qianosuchus followed by Ticinosuchus and aetosaurs.

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
Sterling J. Nesbitt Proceedings of the Royal Society, London B (Suppl.) 270, S234–S237. DOI 10.1098/rsbl.2003.0066

Nesbitt SJ 2005. Osteology of the Middle Triassic pseudosuchian archosaur Arizonasaurus babbitti. Historical Biology. 8 (1): 19–47.

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