Trilophosauridae

Nesbitt, Sterling J., Flynn, John J., Pritchard, Adam C., Parrish, J. Michael, Ranivoharimanana, Lovasoa & Wyss, André R., 2015, Postcranial Osteology Of Azendohsaurus Madagaskarensis (? Middle To Upper Triassic, Isalo Group, Madagascar) And Its Systematic Position Among Stem Archosaur Reptiles, Bulletin of the American Museum of Natural History 2015 (398), pp. 1-126 : 87-88

Trilophosauridae (Bremer 5 1)

SUPPORT: Unambiguous synapomorphies include: postorbital, jugal, and squamosal fit against one another as a “lateral temporal plate” present, with squamosal extending anteriorly to slot into a notch on the jugal (29-1*); ascending process of the jugal intersects between postorbital and squamosal within the supratemporal bar (31-1*); marginal dentition on anteriormost portions of premaxilla and dentary absent (88-1*); crowns of marginal teeth are flattened platforms bearing pointed cusps (93-1*); large anteriorly opening foramen on the anterolateral surface of the maxilla absent (203-1).

Other possible synapomorphies: AC- CTRAN: Anterodorsal process (5 nasal process) of the premaxilla present (3-0); paroccipital process of the opisthotic unflattened and tapered (63-0); parasphenoid crests absent such that a ventral floor of the vidian canal is lacking (66-0); distinct depression on the ventral surface of the braincase at the suture between the basioccipital and the parabasisphenoid (68-1); splenials contribute to mandibular symphysis (85-0); nonserrated marginal teeth (90-0); costal facets very closely appressed to one another with little or no finished bone separation in the anterior postaxial cervical vertebrae (112-1); transverse processes of the anterior caudal vertebrae perpendicular to the long axis of the vertebra (134-0); anterior surface anteromedial to clavicular articulations of the interclavicle smooth (143-0); entepicondylar crest of the humerus exhibits a prominently angled proximal margin (155-1); proximal postaxial margin of metatarsal V forms prominent, pointed process (196-1); postzygapophyses of the anterior cervical vertebrae (presacral vertebrae 3–5) connected through a horizontal lamina (5 transpostzygapophyseal lamina) with a notch at the midline (213-1); posterior caudal vertebrae much longer than the anterior caudal vertebrae (218-1); penultimate phalanges of the pes significantly longer than the more proximal phalanges (235-1); tibial and fibular facets of the astragalus grade smoothly into the anterior hollow (239-0); midcaudal chevrons bears an anterior process resulting in an inverted-T shape (240-1); palatal process of the premaxilla present (247-1). DELTRAN: None.

DISCUSSION: Teraterpeton hrynewichorum , Trilophosaurus buettneri , Trilophosaurus jacobsi ,and Spinosuchus caseanus form a monophyletic group in our analysis (herein termed Trilophosauridae ). The clade is poorly supported from the perspective of decay index (Bremer support), although Te. hrynewichorum and Tr. buettneri share a number unambiguous synapomorphies (as first hypothesized by Sues, 2003). Trilophosauridae is diagnosed by cranial character states of the maxilla and premaxilla (crowns of marginal teeth consist of flattened platform with pointed cusps [93-1]; marginal dentition on anteriormost portions of premaxilla and dentary absent [88-1]), and in the region posterior of the orbit (jugal and squamosal abut to form a “lateral temporal plate,” with squamosal extending anteriorly to slot into a notch on the jugal [29-1]; ascending process of the jugal intersects postorbital and squamosal within the supratemporal bar [31-1]). Although no characters of the postcranium unambiguously diagnose Trilophosauridae , it is important to note that Sues’s (2003) hypothesis is supported by the highly constricted scapula blade (220-1) shared by Te. hrynewichorum and Tr. buettneri .