Crocodylomorphs originated in the Late Triassic and were the only crocodile-line archosaurs to survive the end-Triassic extinction. in a polytomy with two other large bodied taxa (CM 73372 and as well as occupies a key transition at the origin of Crocodylomorpha, indicating that the morphology typifying early crocodylomorphs appeared before SA-2 the shift to small body size. Introduction Crocodile-line archosaurs (Pseudosuchia) underwent a rapid radiation in the wake of the Permian-Triassic mass extinction and came to dominate terrestrial ecosystems by the Late Triassic [1]. Despite their common success, only a single pseudosuchian cladeCrocodylomorphasurvived the end-Triassic extinction event, singlehandedly defining psuedosuchian development for the next 200 million years. Earliest known crocodylomorphs were in large part, gracile, small-bodied, terrestrial forms [2]. However, several large-bodied early crocodylomorphsCand and [6], an archosaur from your Upper Triassic Chatham Group of North Carolina, displays a mosaic of rauisuchid and crocodylomorph character types, which is helping to clarify the earliest development of Crocodylomorpha. Here we present a detailed osteology of was recovered from NCSM locality NCPALEO1902 552-41-0 IC50 in southeastern Chatham County, North Carolina (Fig 1). Uncovered strata consist of red-bed siliciclastics that strike north-northeast and dip 25 southeast. The sediments at this site represent a fluvial environment with lithologic models cycling between rusty-red and purple siltstones (floodplain) and light gray sandstones and conglomerates (river channel) every 5 to 10 meters. NCSM 21558 was collected from a reddish conglomerate with the majority of clasts <1cm in size, suggesting that the animal was deposited in the river channel or crevasse splay adjacent to the channel. Fig 1 Type locality for and to improve resolution among select paracrocodylomorphs, particularly throughout the transition from rauisuchian-grade loricatans to sphenosuchian-grade crocodylomorphs. Details on operational taxonomic models (OTUs), the list of character types, and conversation of character modifications are included in the Supporting Information (S1 and S2 Files). The matrix (S3 and S4 Files) was constructed and edited 552-41-0 IC50 in Mesquite version 2.75 [32] and consists of 214 binary characters and 34 multistate characters, twelve of which are ordered (characters 5, 12, 22, 39, 87, 99, 108, 186, 198, 202, 237, 250). The matrix of 41 taxa and 251 character types was analyzed using PAUP* version 4.0a134 [33]. PAUP* decided 10 character types to be parsimony uninformative 552-41-0 IC50 (character types 10, 78, 167, 176, 181, 182, 205, 208, 219, 243). These character types were excluded a priori when calculating support values to prevent inflation of CI values [34]. Outgroup taxa (Zanno, Drymala, Nesbitt, and Schneider 2015 [6] Holotype NCSM 21558, a partial disarticulated skeleton including several well-preserved cranial bones and elements of the postcranial skeleton. The skull includes a dentigerous correct premaxilla, still left maxilla, still left lacrimal, still left jugal, still left articular, correct angular, and an isolated teeth. Components of the postcranial skeleton are the atlas intercentrum, a cervical neural arch, dorsal neural arch, cervical rib, dorsal rib, gastralium, as well as the still left humerus. Known Specimens NCSM 21623, the shaft and distal end of the right humerus from a smaller-bodied specific. Type Locality NCPALEO 1902 in southeastern Chatham State, NEW YORK, USA. Particular locality data is certainly available by demand in the NCSM. Age group and Horizon A deep red, silty pebble conglomerate from the Pekin Development, Chatham Group, Deep River Basin, Newark Supergroup. Carnian, Triassic Late, 231 Ma approximately. Diagnosis Comes after Zanno et al. [6]. A big bodied (~3m), gracile crocodylomorph recognized from all the basal crocodylomorph taxa by the next features (autapomorphies denoted by an asterisk): elongate, hypertrophied, subtriangular antorbital fenestra (approx. 14 cm anteroposteriorly longer by 6 cm dorsoventrally high at posterior level); posterodorsally trending ridge on lateral surface area of maxilla terminating at advantage of antorbital fenestra*; posterior procedure for maxilla tapers anteriorly, with minimal dorsoventral elevation at anterior part of antorbital fenestra*; ornamented dermal skull bone fragments (premaxilla, lacrimal, jugal, angular); deep antorbital fossa in anterior posterodorsally.