Parasuchus

Extinct genus of reptiles

Parasuchus is an extinct genus of basal phytosaur known from the Late Triassic (late Carnian to early Norian stage) of Andhra Pradesh and Madhya Pradesh, India. At its most restricted definition, Parasuchus contains a single species, Parasuchus hislopi.

The partial premaxillary rostrum (snout) originally described by Lydekker, GSI H 20/11, was chosen as the lectotype of Parasuchus hislopi by Sankar Chatterjee. GSI H 20/11 was collected from the Lower Maleri Formation (Pranhita–Godavari Basin), near the Maleri village of Adilabad district, Andhra Pradesh. The lectotype was rendered obsolete when neotype fossils were approved for the genus in 2003. From the same locality as the neotype, three isolated conjoined basioccipital/basisphenoids (ISI R 45 47) were also recovered. A couple of miles north of that locality, near the Venkatapur village, two more excellently preserved skulls were found. ISI R 160 represents an isolated but nearly complete skull, while ISI R 161 represents partial skull and articulated postcranial remains. about 4 miles west of Tiki village of Shadol District, Madhya Pradesh, is missing only the end of the snout and the squamosal. As the lectotype of the genus, it was found nearby Paradapedon remains.

The two articulated skeletons, ISI R 42 43, alone represent the most complete phytosaurs known to date. Additionally, Parasuchus has been found as one of the most primitive phytosaurs in phylogenetic analyses of Phytosauria, making it very significant for understanding the origin of the Phytosauria. Some studies, like Chatterjee (1978) and Lucas et al. (2007), synonymized Parasuchus with another basal phytosaur, Paleorhinus. If this is the case, the name Parasuchus would have precedence over Paleorhinus because Paleorhinus was named in 1904, nineteen years after Parasuchus was named. A phylogenetic analysis conducted by Kammerer et al. (2016) confirmed that Parasuchus hislopi is nested within the least inclusive clade containing the species Paleorhinus bransoni and Paleorhinus angustifrons. The authors thus considered the genus Parasuchus to be a senior synonym of the genus Paleorhinus (as well as Arganarhinus), and referred the species Paleorhinus bransoni, Paleorhinus angustifrons and Arganarhinus magnoculus to the genus Parasuchus. The cladogram below follows Kammerer et al. (2016).