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A large neosuchian crocodyliform from the Upper () Woodbine

Formation of North

THOMAS L. ADAMS, *, 1 CHRISTOPHER R. NOTO, 2 and STEPHANIE DRUMHELLER 3

1Witte Museum, San Antonio, TX, 78209, U.S.A., [email protected]; 2Department of Biological Sciences, University of Wisconsin–Parkside, P.O. Box 2000,

Kenosha, Wisconsin 53141, U.S.A., [email protected];

3Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee

37996, U.S.A., [email protected]

RH: ADAMS ET AL.—NEW CROCODYLIFORM FROM WOODBINE FM.

*Corresponding author

1 ABSTRACT—A new of neosuchian crocodyliform, Deltasuchus motherali, gen. et. sp. nov., is described on the basis of a partial recovered from the Arlington Site within the Upper Cretaceous (Cenomanian) of north central Texas. This productive locality represents a delta plain ecosystem preserving a diverse coastal fauna including , , (ornithopods and theropods), and crocodyliforms. Prior to this discovery, the only identified crocodyliforms from the Woodbine Formation had been the longirostrine taxa and Woodbinesuchus. This new taxon is differentiated from other known crocodyliforms by the presence of dual pseudocanines on both the dentary and maxilla;; anterior and posterior rami of jugal comparable in depth; anterolaterally facing margin on the dorsal portion of the postorbital; contact between the descending process of the postorbital and the ectopterygoid; and a large, deep fossa on the ventral surface of the quadrate.

Phylogenetic analysis recovers D. motherali as the sister taxon to Paluxysuchus newmani from the Lower Cretaceous Twin Mountains Formation of Texas. This lies within to + . The associated cranial elements of this new crocodyliform represent a large, broad snouted individual, an ecomorphotype often associated with the semi- aquatic ambush predator niche in this clade, and one not previously reported from the formation.

2 INTRODUCTION

The terrestrial record of in the Cretaceous is characterized by major temporal and spatial biases. In the Lower Cretaceous, rich fossil deposits are concentrated in the

Aptian and , while the Upper Cretaceous fossil record is dominated by and

Maastrichtian assemblages (Weishampel et al., 2004). The stretch of time in between, representing roughly 20 million , is comparatively poorly sampled (Jacobs and Winkler,

1998; Zanno and Makovicky, 2013). Additionally, the majority of these are known from the western continent of Laramidia. Relatively little is known about to the east, separated from the better studied, Laramidian assemblages by the

(Ullmann et al., 2012; Krumenacker et al., 2016; Prieto-Márquez et al., 2016).

Recent research at the Arlington Archosaur Site (AAS), a fossil-rich outcropping of the

Woodbine Formation located in the suburban enclave of Arlington, Texas, is starting to fill in this gap (Fig. 1). The AAS preserves a coastal environment, with both marine and freshwater influences, that includes , bony , lungfish, turtles, lissamphibians, , crocodyliforms, and ornithopod and theropod dinosaurs (Noto et al., 2012). The site has been dated to the Cenomanian, placing it within the sparsely sampled middle Cretaceous interval.

Deposited within an extensive deltaic system on the southwestern margin of Appalachia, the site also provides a window into the diversity of this poorly understood landmass.

Here we present a new of crocodyliform from the AAS. While crocodyliform fossils are relatively common throughout the middle Cenomanian (96 Ma) Woodbine Formation of north-central Texas, their remains are typically fragmentary and represented by isolated teeth, vertebrae, and (Lee, 1997a; Head, 1998; Jacobs and Winkler, 1998; Adams et al.,

3 2011). Previously, the only two taxa recognized from the Woodbine Formation have been

Terminonaris Osborn, 1904 and Woodbinesuchus Lee, 1997 (Adams et al., 2011). Both these taxa are longirostrine neosuchians, with Terminonaris having been interpreted to occupy marginal to fully marine paleoenvironments (Hua and Buffetaut, 1997; Wu et al., 2001). The

AAS, with its unusually well-preserved fossils in comparison to other Woodbine localities, has yielded at least four crocodyliform taxa, based on numerous isolated cranial and postcranial remains (Adams et al., 2015; Noto, 2015). The dominant constituent of the assemblage is a new species represented herein by a partial skull from a single large individual. The aim of this study is to describe this new crocodyliform taxon from the AAS and to assess its evolutionary relationships and ecological role in a middle Cretaceous coastal community.

Anatomical Abbreviations—bo, basioccipital; bos, basioccipital ; cqc, cranio- quadrate canal; ect, ectopterygoid; ects, ectopterygoid sutural surface; exos, exoccipital sutural surface; fae, foramen aëreum; gf, glenoid fossa; ics, intercondylar sulcus; itb, intertemporal bar; j, jugal; js, jugal sutural surface; leu, lateral Eustachian foramen; lhc, lateral hemicondyle; meu, median Eustachian foramen; mg, maxillary groove; mhc, medial hemicondyle; mx, maxilla; na, nasal; nar, naris; nvf, neurovascular foramina; oto, otoccipital (opisthotic-exoccipital); parop, paroccipital process; pcf, posterior carotid foramen; pmx, premaxilla; po, postorbital; pob, postorbital bar; polp, postorbital lateral process; pop, postorbital process; pts, pterygoid sutural surface; q, quadrate; qad, quadrate anterodorsal process; qat, adductor tubercle of the quadrate; qd, quadrate dorsal process; qjs, quadratojugal suture; qpt, quadrate pterygoid process; qfv, ventral fossa of the quadrate; qs, quadrate suture; roe, external otic recess; sps, splenial suture; sq, squamosal; sqs, squamosal sutural surface; sus, surangular sutural surface; sym, mandibular

4 symphysis; IX–XI, foramen for glossopharyngeal, vagus, and accessory nerves; XII, foramen for hypoglossal nerve.

Institutional Abbreviation—DMNH, Perot Museum of Nature and Science, Dallas,

Texas, U.S.A.; SMU, Southern Methodist University Shuler Museum of , Dallas,

Texas, U.S.A. ; TMM, Texas Memorial Museum, University of Texas, Austin, Texas, U.S.A.

AGE AND GEOLOGIC SETTING

The Upper Cretaceous Woodbine Formation of North Texas unconformably overlies the

Grayson Marl, the uppermost formation of the Washita Group, and is overlain by the Eagle Ford

Group (Fig. 2A; Dodge, 1969; Lee, 1997a, 1997b; Jacobs and Winkler, 1998). In outcrop, it extends from the Red River and thins to the south (Dodge, 1969; Jacobs and Winkler, 1998).

Dodge (1969) designated four lithologic units within the formation near Dallas and Fort Worth, in ascending : the Rush Creek, Dexter, Lewisville, and Arlington members. The lower

Woodbine sediments (Rush Creek and Dexter members) represent marginal marine to fully marine deposits (Bergquist, 1949; Dodge, 1969; Oliver, 1971). The uppermost Lewisville and

Arlington members represent a terrigenous coastal depositional system with fluvio-deltaic influences (Powell, 1968; Dodge, 1969; Lee, 1997a, 1997b; Jacobs and Winkler, 1998). The

Arlington Archosaur Site is located within the Lewisville Member of the upper strata of the

Woodbine Formation (Fig. 2A). The ammonite Conlinoceras tarrantense, a zonal marker for the base of the middle Cenomanian, was found within the Lewisville Member and in the Tarrant

Formation (lowermost ), indicating an age no younger than early middle

5 Cenomanian (approximately 96 Ma; Kennedy and Cobban, 1990; Emerson et al., 1994; Lee,

1997a; Jacobs and Winkler, 1998; Gradstein et al., 2004).

PALEOECOLOGY AND TAPHONOMY

The Arlington Archosaur Site preserves a diverse community of , invertebrates, and plants deposited in a lower delta plain system created during a regressive phase along the southeastern margin of the Western Interior Seaway (Oliver, 1971; Main, 2005;

Adams and Carr, 2010; Noto et al., 2012). Exposures consist of a hillside 200 m in length, with approximately 50 m representing the main fossil quarry (Fig. 2B). South of the hillside patches of sandstone containing teeth, trace fossils representing a Skolithos ichnofacies, and ripple marks are exposed (Seilacher, 2007; Main, 2013). While their precise relation to hillside exposures is uncertain, the sandstone likely sits lower in section. The following description includes the most common and laterally extensive facies of the hillside exposure.

Facies A forms the primary fossil quarry from which the majority of specimens have been recovered. It consists of a dark brown sandy siltstone at least 50 cm deep overlain by a 30–

40 cm thick dark gray layer of carbonaceous sandy siltstone, the upper portion of which contains slickensides. Sulfur bands, gypsum, and pyrite are prevalent throughout this layer. Abundant plant material is preserved in the form of broad, lenticular mats of featureless carbonized remains as much as 4 cm thick, compressed but well-preserved carbonized tree sections 15–20 cm wide, and smaller fragments of permineralized wood (Main, 2013). A high abundance of terrestrial palynomorphs (primarily ferns), well-preserved microscopic organic matter, rare dinoflagellates,

6 absence of , lungfish toothplates, non-marine turtles, and lissamphibians, indicates fluvial deposition with minor marine input (Main, 2013). Fragmentary remains of elasmobranchs and osteichythyans representing individuals a meter or more in length suggest the nearby presence of deeper water. Invertebrate remains consist mainly of gastropods, containing a mixture of freshwater and brackish groups (Main, 2013). Facies A is interpreted as a low-energy freshwater or brackish system, such as a tidal coastal wetland proximal to a river channel

(Rabenhorst, 2001).

Facies B is a 40–50 cm thick blocky gray siltstone with a variable medium to very fine sand content. Large, intersecting slickensides, root traces, and possible infilled desiccation cracks or clastic dikes are common. The top 5–10 cm changes color to a light brown and contains an abundance of charcoal and invertebrate burrows. Large root systems 20–30 cm wide are preserved in situ as charcoal and encased in carbonate mineral concretions (mainly siderite)

(Main et al., 2010). Hadrosauroid fossils attributed to byrdi were previously described from this layer (Noto et al., 2013; Main et al., 2014). Rare shells of aquatic invertebrates are present. Facies B represents a paleosol with a seasonally-variable water table, possibly a vertisol or gleysol that was proximal to a fluvial channel (Retallack, 2001).

Facies C consists of siderite-cemented silt nodules up to 10 cm in diameter and coarse- grained siderite-cemented slabs 2–5 cm thick with an erosional base. Some slabs are densely packed with invertebrate burrow traces that penetrate the underlying layer. Deformation of overlying bedding indicates post depositional diagenetic siderite precipitation. Fossils are rare but when present belong to predominantly brackish or marine taxa. This abrupt transition in section from terrestrial to marine environments may represent an unconformity brought on by subsidence under a prograding delta front and/or rise in sea level (Coleman and Prior, 1981).

7 Facies D is formed from a ~1 m thick interbedded fine white sand and gray siltstone alternating in layers 0.1–0.5 cm thick, with occasional interspersed layers of sand 5–10 cm thick, some of which contain ripple marks. Fossils in this facies are rare and belong to marine invertebrates. Facies D is a marine-influenced environment of active, cyclic deposition.

Alternating sand-silt systems are not uncommon in prograding deltas and this facies may represent a mudflat from the intertidal zone or a distal bar/distributary bar in the subaqueous delta plain (Coleman and Prior, 1981; Fan and Li, 2001). In both cases the thicker, sand-dominated layers may represent storm deposition.

The taphonomy of the hadrosauroid remains in Facies B was described previously (Main et al., 2014). remains forming the taphocoenosis in Facies A are well preserved yet almost completely disarticulated, with some elements separated by 2 to 3 meters. When associated, elements are often contorted out of anatomical position. There is little evidence of long-distance aqueous transport or prolonged subaerial weathering features, indicating a parautochthonous origin. Some specimens possess crocodyliform bite marks, whose feeding behavior may have contributed to the disarticulation of remains and overall macrovertebrate accumulation in this area (Noto et al., 2012). However these marks are only present on a small proportion of bones and therefore cannot explain the widespread disarticulation. A more likely mechanism involves seasonal or tidally-forced fluctuations in water level that displaced remains short distances, disarticulating and spreading the remains over time with minimal damage.

Closely-packed wetland plants may have prevented long distance transport by forming barriers that captured and held remains. Postburial, seasonal shrink-swell cycles in the overlying paleosol contributed further to disarticulation via pedoturbation. The shrink-swell cycling may also explain the distortion of some remains, particularly those close to the contact with the overlying

8 paleosol. The fragmentary meso- and microvertebrates display a variety of preservation modes, suggestive of an allochthonous origin, likely deposited during periodic flooding from storm surges, increased wet season run off, or extreme high tides.

The majority of fossil accumulation occurred in a tidal freshwater or brackish coastal wetland followed by soil development in a proximal floodplain of a lower delta plain. The mixture of terrestrial, freshwater, brackish, and marine taxa reflects the proximity of the site to the paleocoastline (McNulty and Slaughter, 1968; Russell, 1988; Cumbaa et al., 2010). The area was densely vegetated with small and medium trees, ferns, and some angiosperms (Main, 2013).

Slickensides, desiccation cracks, and clastic dikes are indicative of a seasonally dry climate

(Retallack, 2001; DiMichele et al., 2006). Dry seasons were marked by periodic wildfires, represented by at least three distinct charcoal-bearing horizons including clastic debris-flows, in- situ burned root systems, and abundant small charcoal fragments (Main et al., 2010). Wildfires were widespread and frequent in the Cretaceous and likely played a large role in structuring the

AAS community (Brown et al., 2012).

SYSTEMATIC PALEONTOLOGY

CROCODYLIFORMES Hay, 1930

MESOEUCROCODYLIA Whetstone and Whybrow, 1983

NEOSUCHIA Benton and Clark, 1988

DELTASUCHUS, gen. nov.

Type Species—Deltasuchus motherali, sp. nov.

9 Etymology— Deltasuchus, ‘Delta’ in reference to the coastal delta plain deposits of the

Woodbine Formation in which the new taxon was found; and ‘suchus’, derived from ‘Souchos’, the Greek term for the Egyptian god, .

Diagnosis—As for the type and only known species.

DELTASUCHUS MOTHERALI, sp. nov.

(Figs. 3–10)

Holotype—DMNH 2013-07-0001, partial skull and mandible.

Referred Material—DMNH 2013-07-0004, left otoccipital; DMNH 2013-07-0004, right surangular. DMNH 2013-07-0164, DMNH 2013-07-0043, DMNH 2013-07-0165, DMNH 2014-

06-04, isolated teeth.

Diagnosis—A neosuchian crocodyliform differing from other known neosuchians in having the following combination of characters (* denotes autapomorphies): moderately enlarged supratemporal fenestrae; dual pseudocanines on both the dentary and maxilla; anterior and posterior rami of jugal comparable in depth; anterolaterally facing margin on the dorsal portion of the postorbital; contact between the descending process of the postorbital and the ectopterygoid; deep fossa on the ventral surface of the quadrate*; medial quadrate condyle expands ventrally, separated from lateral condyle by deep intercondylar sulcus.

Etymology—Deltasuchus motherali, in honor of Austin Motheral, who discovered the type specimen.

10 Locality and Horizon—The Arlington Archosaur Site, city of Arlington, Tarrant

County, Texas. Upper Cretaceous (Cenomanian) Woodbine Formation (see above). Exact locality data is on file at the Perot Museum of Nature and Science, Dallas, Texas.

DESCRIPTION

General Description

The specimen of Deltasuchus motherali gen. et sp. nov. (DMNH 2013-07-0001) is represented by disarticulated cranial and mandibular remains. Elements were found within the same bedding horizon, in close association (across approximately 5–7 square meters). There is no duplication of elements, and, when reconstructed, adjacent elements articulate along sutural surfaces (Fig. 3A). When taken together, these lines of evidence strongly support the interpretation that these elements can be positively associated and represent the remains of a single individual. The stoutly constructed maxillary rostrum is nearly complete, missing the anterior portion of the nasals, the prefrontals, and the lacrimals. Posterior to the orbits, skull elements include a left postorbital, left jugal, fragmentary right squamosal, right otoccipital, basioccipital, partial left and right pterygoids, left and right ectopterygoids, and both quadrates

(Table 1). Lower jaw elements include the most of the mandibular rostrum, comprising the left and right anterior portions of each dentaries, along with a partial right surangular and right articular. All elements are relatively well preserved with no signs of deformation. Heavy sculpturing in the form of subrounded and elongated pits occurs on the dermal surface of the cranium and lower jaws. Several axial and appendicular elements have been found in association with the holotype material. However, the presence of more than one large crocodyliform taxon

11 from the Arlington Archosaur Site and the generally conservative morphology of the postcranial elements of Terminonaris robusta Mook, 1934 and Woodbinesuchus byersmauricei Lee, 1997a currently prevent confident assignment of these elements to Deltasuchus.

Reconstructed, the estimated skull length (measured along the midline from the basioccipital to the anterior margin of the premaxilla) is 800 mm. In dorsal view, the outline of the skull is triangular (Fig. 3B). The rostrum is platyrostral and represents 65% of the reconstructed cranium length. The width across the quadrate condyles is estimated to be 460 mm.

The width across the premaxillomaxillary suture is 130 mm. Total body length for the holotype specimen can be estimated from the length of the reconstructed skull (DMNH 2013-07-0001).

Based on surveys of porosus and Crocodylus niloticus populations (Schmitt, 1944;

Hutton, 1987), body length in crocodylians and their close relatives has been cited as roughly seven times the length of their . However, that method has been shown to underestimate total length (Hutton, 1987). Further studies based on those two species of Crocodylus have supported a head-to-total body length ratio as high as 1:7.5 (Wermuth, 1964; Bellairs, 1969;

Greer, 1974). A regression performed on a recent dataset representing 58 individuals across 20 extant species (Drumheller and Brochu, 2016) also yields higher calculated total lengths (y =

7.3381x-2.0553; r2 = 0.956), indicating that these estimations are broadly applicable beyond just

Crocodylus. Using those studies to set minimum (Schmitt, 1944) and maximum (Bellairs, 1969) estimations, the holotype specimen is predicted to have been between 5.6 and 6.0 m in total body length.

Premaxilla

12 The left and right premaxillae are preserved in four pieces (Fig. 4A, B). External ornamentation comprises of shallow, widely spaced pits. When articulated, the premaxillae completely enclose the narial opening, which is oriented dorsally. In dorsal view, the anterior edge of the prenarial rostrum of the premaxilla is rounded in outline. The anterior margin of the naris has a small posteriorly directed process giving the interior margin of the naris a - shaped appearance, being wider (750 mm) than it is long (650 mm). Internally, the medial wall of the naris contains a small, shallow fossa about 1 cm in diameter. The dorsal margin of the narial rim is elevated above the level of the maxilla. Posteriorly, the premaxillae meet at the midline along an edge-to-edge suture to exclude the nasals from the posterior margin of the naris.

Along this midline suture the dorsal surface is slightly depressed. The premaxillomaxillary suture is obliquely oriented dorsally along a butt joint. Although the posteriormost projections of the premaxillae are not preserved, they extend as a wedge between the maxillae and the nasals.

Along the lateral surface, just anterior to the premaxilla-maxillary contact, is a well developed notch for the placement of the 4th dentary pseudocanine. In palatal view, four premaxillary alveoli are preserved on each side of the rostrum (Fig. 4B). The palatal surface is not preserved.

Maxilla

Like the premaxillae, the left and right maxillae are preserved as four pieces (Fig. 4C, D).

The dorsal surface is heavily ornamented with pits and grooves. In dorsal view, the lateral borders of the maxillae are weakly sinusoidal to straight, with a large lateral bulge at the level of the fourth and fifth maxillary alveoli. The anterior portions of the maxillae are slightly upturned dorsally. The vertically oriented lateral margins are smooth, separating the rugose dorsal surface from the alveolar margin. Large maxillary neurovascular foramina are evenly spaced linearly

13 along the length of the dorsolateral margin of the maxillae. There is an anteroposteriorly directed groove on the posterolateral surface of the posterior maxillary process that is aligned with the neurovascular foramina. It extends to the maxillojugal suture. The maxillae have an edge-to-edge contact with the nasals along its anteromedial margins. The posteromedial margins of the maxillae are overlapped dorsally by the lacrimals. The posterior maxillary process passes lateral to the orbits and ventromedially to the jugal, and contacts the anterior process of the ectopterygoid just anterior to the postorbital bar. The palatal processes of the maxillae are not preserved.

There are 22 maxillary positions in the right maxilla, with 16 preserved in the left

(Fig. 4D). The alveoli increase in size from the first alveolus to the fourth and fifth alveoli, which are the largest (Table 2). These large alveoli are roughly equal in diameter (~24 mm), resulting in dual pseudocanines (enlarged, canine-like teeth). This produces a very distinct lateral bulge in the maxillary margin. The diameter of alveoli increases in size from the sixth through the eleventh alveolus and gradually decreases thereafter. All maxillary alveoli are separated by septa.

Nasal

The paired nasals meet at the midline along a straight butt joint (Fig. 4E, F). They extend anteriorly to the same level as the anterior margin of the maxillae and are excluded from the posterior border of the naris. The nasals gradually narrow anteriorly. The posterior portions of both nasals are not preserved. The dorsal surface is ornamented with oval depressions and shallow grooves.

Postorbital

14 The left postorbital is a tri-radiate element and is ornamented with rounded pits (Fig. 5A,

B). In dorsal view, the postorbital forms a rounded anterolateral corner of the cranial table. Both the intertemporal bar and the posteriorly directed ramus are rod shaped and roughly equal in size.

Their narrow shape and the broad curvature of the anterolateral margin suggest that D. motherali had enlarged supratemporal fenestra on a broad skull table (fenestra width approximated to be

20% of the width of the reconstructed skull table; Fig. 3B). Along the anterior border of the intertemporal bar, the postorbital forms a narrow fossa along the posterior margin of the orbit. A similar fossa occurs posteriorly on the anterolateral margin of the supratemporal fenestra. The lateroventrally descending process of the postorbital bar occurs along the anterolateral facing margin of the postorbital. The descending postorbital process overlaps the entire ascending process of the jugal medially contacting the ectopterygoid ventrally (Fig. 5C). Together, the descending postorbital process and the ascending process of the jugal form a rugose, dorsoventrally oriented boss extending laterally from the postorbital bar. The postorbital bar is short and robust with an elliptical cross-section.

Jugal

The left jugal is an anteroposteriorly elongated tri-radiate element (Fig. 5D–F). The external surface is densely sculptured. The anterior ramus is triangular in cross-section and wedges between the posterolateral process of the lacrimal dorsomedially and the maxilla ventrally. Anterior to the ascending process, the jugal forms a narrow, raised rim along the posterolateral margin of the orbit. A V-shaped notch occurs on the anterodorsal surface of this rim for articulation with the lacrimal. The smooth medial surface of the anterior ramus curves medially onto the postorbital bar. The ascending process of the jugal that forms the postorbital

15 bar occurs at the midpoint of the jugal and is directed anterodorsally (Fig. 5C). Although the posterior ramus of the jugal is incomplete, it is similar in dorsoventral depth to the anterior ramus. The ventromedial surface of the jugal has a rugose notch for articulation with the ectopterygoid.

Squamosal

The right squamosal is represented by a poorly preserved posterolateral corner of the element (Fig. 5G). Although it is heavily eroded, the dorsal surface shows the indication of sculpturing. As in other crocodyliforms, the posterior dorsal lamina overhangs the lateral margin of the squamosal and forms the dorsal surface of the external otic recess. Posteriorly, the medioventral surface forms the roof and lateral wall of of the cranio-quadrate canal.

Quadrate

The left quadrate is poorly preserved. However, the right quadrate is very well preserved, missing only a portion of the quadrate-quadratojugal articular surface (Fig. 6). The quadrate is a robust and broad element. The inclined anterodorsal process of the quadrate is continuous with the dorsal process, forming the floor of the internal auditory canal (Fig. 6A). The anterodorsal process forms the posterior and ventral margin of the external otic recess. The anterodorsal surface of the quadrate body is strongly rugose representing the broad articulation with the ventral surface of the squamosal and the lateral part of the exoccipital. These articular surfaces are separated by the posteromedially directed floor of the cranio-quadrate canal. The cranio- quadrate canal is completely enclosed superiorly by the paroccipital process of the otoccipital and the squamosal. Posterolaterally, the quadratojugal sutural surface runs parallel to the

16 quadrate to contact the posterolateral corner of the lateral hemicondyle, indicating that the quadratojugal contributed partially to the craniomandibular joint.

The ventral surface of the quadrate body is characterized by a series of elongate crests corresponding to areas of attachment for the mandibular adductor muscles (Fig. 6B, C). A sizable crest (crest B of Iordansky, 1973) originates from the posteromedial margin of the pterygoid ramus of the quadrate forming a posteromedially concave ridge terminating in a pronounced adductor tubercle at the approximate midpoint of the body of the quadrate. From this point, crest B’ (sensu Iordansky 1973) extends posteriorly for a short distance. Together, crest B and B’ form the lateral border of a large recess (about 30 mm maximum depth), causing the ventromedial surface of the quadrate to be markedly concave (Fig. 6C). A prominent ventrally concave ridge corresponding to crest A’ of Iordansky (1973) extends parallel and medial to crest

B from the dorsal process of the quadrate to taper at the midpoint tuberosity. Lateral to crest B’ along the posterior portion of the quadrate-quadratojugal suture is an obliquely oriented crest A

(sensu Iordansky 1973), which is much shorter and weakly developed than the former. These unusually well developed crests may provide larger attachment points, with the resulting deep fossa potentially providing space for muscle expansion during jaw adduction.

The distal quadrate ramus projects posteroventrally and lateral to the occiput. A small foramen aëreum is present on the medial dorsal surface just anterior to the medial hemicondyle and lateral to the paroccipital process (Fig. 6A). The expanded mandibular condyle is subdivided into lateral and medial hemicondyles by a deep intercondylar sulcus. The wedge-shaped medial hemicondyle slants medioventrally and is smaller than the broader, horizontally aligned lateral hemicondyle (Fig. 6D).

17 Otoccipital

The right otoccipital is partially complete and heavily weathered (Fig. 7A–C). The left otoccipital DMNH 2013-07-0004 is well preserved and is 85% the size of the right, representing a slightly smaller individual (Fig. 7D). The otoccipital is a broad, subrectangular element with the laterally projecting paroccipital process forming most of the occiput. Dorsomedially, the otoccipitals meet and form the dorsal and lateral margins of the foramen magnum and terminate at the dorsolateral corner of the occipital condyle. Dorsolaterally, the paroccipital process overlies the descending laminae of the squamosal and the dorsal process of the quadrate along broad rugose sutures (Fig. 7B). When reconstructed, the paroccipital process does not appear to extend beyond the lateral margin of the squamosal. The cranio-quadrate canal opens along the ventrolateral margin of the paroccipital process, passing anteromedially between the otoccipital and quadrate. Below the metotic crest, the ventral margin of the paroccipital process has a convexity projecting ventrally. It is uncertain if the posterolateral margin of this convexity participates in the basioccipital tubera. Ventrolateral to the foramen magnum and occipital condyle, the medial surface of the otoccipital bears five foramina. Just lateral to the foramen magnum, a large foramen served as the exit for the hypoglossal nerve (CN XII). Ventrolateral to the hypoglossal foramen are three closely grouped foramina that presumably served as openings for the glossopharyngeal (IX), vagus (X), and accessory nerves and the jugular vein.

Immediately ventral to these foramina is the ventrolaterally directed posterior carotid foramen for passage of the internal carotid artery.

Basioccipital

18 The basioccipital is eroded along the left posteroventral margin, but otherwise is well preserved (Fig. 7E–G). It forms the majority of the occipital condyle, which is broader than tall.

Along the dorsal surface of the occipital condyle, a shallow channel extends anteroposteriorly along the floor of the foramen magnum. In lateral view, the occipital condyle extends posteriorly with a broad basioccipital plate projecting posteroventrally to the condyle at approximately a 30° angle. The basioccipital plate is trapezoidal shaped with bilateral tubercles ventrally directed along the margins, and two sub-parallel sagittal crests (Fig. 7F). It is unknown if these sub- parallel crests extended onto the ventral surfaces of the bilateral tuberosities. The posterior margins of the median Eustachian foramen is preserved on the anterior face of the basioccipital, opening between the two medial tubercles. The lateral Eustachian foramina are positioned just anterior to the occipital condyle along the dorsolateral surface (Fig. 7E).

Ectopterygoid

Both the left and right ectopterygoids are nearly complete (Fig. 8A–C). The ectopterygoid articulates along the medial surface of the jugal so that the anterior process contacts the posterior maxillary process. The ascending process of the ectopterygoid articulates into a rugose, triangular notch on the ventral and posteromedial side of the ascending process of the jugal (Fig. 8D). Dorsally, it contacts the descending process of the postorbital bar. The descending pterygoid process of the ectopterygoid is broad and triangular in shape. It articulates along the anterolateral edge of the pterygoid flange.

Pterygoid

19 Only the anterolateral descending flanges of the left and right pterygoids are preserved

(Fig. 8E, F). The flanges have a broad, flat ventral surface that faces anteriorly. The anterior edge of the flange is directed posterolaterally. The broad, descending pterygoid process of the ectopterygoid overlaps the lateral border of the pterygoid flange. The articular surface on the remaining fragments of the pterygoid indicates that the ectopterygoid did not extend to the posterior tip of the lateral pterygoid flange.

Dentary

The dentaries consist of only the anterior portion of the spatulate mandibular rostrum and a fragment of the ramus (Fig. 9A–C). The anterior margin of the dentary is transversely broad and straight. The ventral and lateral surfaces of the dentary are ornamented with widely spaced pits and shallow grooves. Anteriorly, the mandibular rostrum is low with a shallow concave dorsal surface. In dorsal aspect, the symphyseal portion of the rostrum extends caudally to a point level with the eighth dentary alveolus. A long and narrow Meckelian groove extends forward to the symphysial margin along the medial surface of the dentary. Although the splenial is missing, it appears that the splenial participated in the mandibular symphysis anteriorly (Fig.

9C). On the dorsal surface, medial to the tooth row, is a string of small neurovascular foramina.

Neurovascular foramina also occur along the lateral surface below the alveolar margin. The anterior alveoli are procumbent. Alveoli 1 – 4 are transversely aligned, with the 4th alveolus lateral and posterior to the first; all are separated from each other by bony septa. Alveoli 3 and 4 are the largest of the dentary, again resulting in dual pseudocanines. The alveoli posterior to the symphysis are also separated by septa. Though incompletely preserved, each ramus was likely straight, matching the straight margin of the maxilla.

20 Surangular

The surangular is dorsoventrally tall and mediolaterally compressed (Fig. 9D). The dorsal margin is thickened while the ventral margin is thin and contains a smooth projection that is a remnant of the articulation with the angular. The retroarticular process appears short and its dorsal surface is caudoventrally angled in lateral view. The anterior edge of the retroarticular process contains a shallow depression marking the lateral border of the mandibular fossa.

Presence of an external mandibular fenestra is unknown due to poor preservation of the anterior portion. The lateral surface is heavily ornamented with large, closely-packed pits oval to rectangular in shape.

Articular

The right articular is missing the posterior portion of the retroarticular process and is covered with a series of iron mineral concretions (Fig. 9E–G). It articulates with both the right surangular and right quadrate. The glenoid fossa is figure eight-shaped, composed of two asymmetric depressions bisected by a prominent ridge that widens ateroinferiorly. Each depression closely matches the shape and orientation of the corresponding hemicondyles on the right quadrate. A prominent dorsal ridge marks the posterior border of the glenoid fossa. In lateral view, the sutural surface for the surangular is triangular in shape and extends along the majority of the preserved retroarticular process, indicating the surangular participated in the glenoid surface. In medial view the process is notable for being extremely thin. While the full length of the retroarticular process is unknown, the preserved portion shows it was most likely a

21 broad and spatulate structure, with a gently concave dorsal surface. The retroarticular process was oriented horizontally relative to the long axis of the mandible.

Dentition

A series of five unerupted teeth are present in distal alveoli of the right and four in the distal alveoli of left dentary (Fig. 9A). The teeth are typical of those seen among basal crocodyliforms, being relatively isomorphic and conical in shape with a circular cross-section

(Fig. 10). All crowns possess a mild labial curvature that is more strongly developed in the larger, shed crowns. The unerupted crowns preserve closely spaced enamel ridges running parallel to each other without anastomosing (Figure 10A). These ridges terminate shortly before the apex of the crown, creating a distinct circumferential lip. Mesial and distal carinae are present, both lacking denticles, and stretch from base to the apex.

Several isolated shed crowns of varying size have also been recovered throughout the quarry (Figure 10B, C). Isolated crowns referable to Deltasuchus motherali gen. et sp. nov. are large, measuring upwards of 55 mm in length and 20 mm in basal width, which matches well with diameters of the largest alveoli in the maxilla and dentary. Crowns exhibit the same pattern of longitudinal enamel ridges terminating before the apex, except this smoother area takes up a larger portion of the apex and does not form a distinct circumferential lip (Fig. 10). Carinae lacking denticles are present. Both enamel ridges and carinae become less prominent with increasing tooth size. These teeth can be distinguished from the teeth of Woodbinesuchus and

Terminonaris, which are more elongate, lingually curved, and lack the smooth apex.

22 PHYLOGENETIC ANALYSIS

Deltasuchus motherali gen. et sp. nov. was added to the data matrix of Turner (2015) which included 318 osteological characters (Appendix 1). Following Martin and Buffetaut

(2012), character 207 was modified with an additional state added to cover the range of morphologies observed for the maxillary depression: maxillary depression absent (207:0), maxillary depression present (207:1); and maxillary depression expanding to or on jugal as a maxillojugal groove (207:2). Taxon sampling was revised for a total of 101 crocodylomorph taxa with Gracilisuchus stipanicicorum as the outgroup. This phylogenetic dataset was analyzed with equally weighted parsimony using TNT v. 1.0 (Goloboff et al., 2003a, 2008). A heuristic tree search strategy was conducted performing 1000 replicates of Wagner trees (using random addition sequences) followed by TBR branch swapping (holding 10 trees per replicate). The best trees obtained at the end of the replicates were subjected to a final round of TBR branch swapping. Zero-length branches were collapsed if they lack support under any of the most parsimonious reconstructions. Character support of the nodes present in the most parsimonious reconstructions was calculated using bootstrap analysis of 1000 replicates and Bremer support

(Bremer 1988, 1994). The topologies obtained during the bootstrap replicates are summarized using frequency differences (Groups present/Contradicted, GC), following Goloboff et al.

(2003b). Phylogenetic nomenclatural and clade definitions follow that of Brochu et al. (2009) and Turner (2015).

The analysis resulted in 88 most parsimonious trees, with a length of 1650 steps, a consistency index (CI) of 0.241, and a retention index (RI) of 0.671 (Figs. 11). Except for the

23 inclusion of Deltasuchus motherali gen. et sp. nov., the overall topology does not vary from that of Turner (2015). D. motherali was recovered inside Neosuchia in all 88 most parsimonious trees as the sister taxon to Paluxysuchus newmani. This clade has moderate nodal support (bootstrap value of 37 and Bremer support of 5) and is supported by two synapomorphies: anterior part of the jugal with respect to posterior part is as broad (character 17.0; reversal to the primitive condition for ); vascular opening in dorsal surface of postorbital bar absent

(character 27.0; reversal to the primitive condition for Crocodyliformes). The clade containing

Paluxysuchus + Deltasuchus is the to Goniopholididae + Eusuchia. This topology is supported by five synapomorphies: enlarged maxillary teeth curved in two waves (festooned, character 79.2); mandibular symphysis in lateral view is shallow and anteriorly convex

(character 103.3); lateral contour of snout in dorsal view is sinusoidal (character 178.1); prefrontal pillars when integrated in are transversely expanded in their dorsal part and columnar ventrally (character 182.1); ventral edge of maxilla in lateral view is sinusoidal

(character 183.1). A Paluxysuchus + Deltasuchus clade located basal to Goniopholididae +

Eusuchia indicates a significant ghost lineage as the goniopholidid ancestry originates early with the Early occurrence of valliceps (Tykoski et al., 2002; Adams 2013).

DISCUSSION

Comparisons—The holotype specimen of Deltasuchus motherali gen. et sp. nov.

(DMNH 2013-07-0001) is easily differentiated from the other two large crocodyliforms known from the Woodbine Formation of Texas; Woodbinesuchus byersmauricei Lee, 1997a and

24 Terminonaris cf. T. robusta (Fig. 12; Adams, et al. 2011). Both these taxa are longirostrine neosuchians with tubular snouts, while D. motherali has a broad platyrostral rostrum. Even though the splenial of D. motherali has involvement in the mandibular symphysis, it is not as far- reaching as the elongate symphyses observed in these longirostrine taxa which extend to the

13th–14th alveolus (Lee, 1997a; Wu et al., 2001; Adams, et al. 2011).

The overall skull morphology of D. motherali closely resembles several species of

Goniopholididae: crassidens Owen, 1841; Goniopholis simus Owen, 1878;

Amphicotylus lucasii Owen, 1878; Amphicotylus gilmorei Holland, 1905; and Amphicotylus stovalli Mook, 1964. Shared features include nasals which do not participate in the narial border; enlarged supratemporal fenestra on a broad skull table; and participation by the splenial in a short mandibular symphysis. However, D. motherali lacks the wide spatulate-shaped premaxillae seen in goniopholidids and some pholidosaurids, andthe cranio-quadrate canal of D. motherali is completely enclosed superiorly by the paroccipital process of the otoccipital and the squamosal, unlike the more open canal of goniopholidids in which the paroccipital process does not form a suture with the quadrate. The narrow groove on the posterior maxillary process of DMNH 2013-

07-0001 extends to the maxillojugal suture, but it is difficult to determine if it overlapped the anteroventral margin of the jugal, as seen in pholidosaurids (Fig. 13; Martin and Buffetaut,

2012). It differs from the the distinctive maxillary fossa on the lateral margin of the snout that is typically associated with the clade Goniopholididae and in purbeckensis, which are large ovoid depressions (Martin et al., 2016). The narrow groove of D. motherali is similar to much of the surface sculpturing and may be a confluence of several maxillary neurovascular foramina, a condition that also seems to be present in some pholidosaurids, such as imperator Broin and Taquet, 1966 and cherifiensis Lapparent de Broin, 2002(Martin

25 and Buffetaut, 2012). In Addition, D. motherali has only four premaxillary alveoli (Fig. 4B), while goniopholidids and pholidosaurids such as G. crassidens, G. simus, A. lucasii, A. gilmorei,

A. stovalli, S. imperator, E. cherifiensis, and T. robusta all have 5 premaxillary alveoli.

The sub-parallel crests on the basioccipital of D. motherali show similarities to the muscle scars described by Martin et al. (2016) on the ventral edges on the bilateral tuberosities of the basioccipital of P. purbeckensis. However, the crests of D. motherali form sharp ridges, while those figured for P. purbeckensis appear to be more rounded (Martin et al., 2016:fig. 6).

In addition, the lobes of P. purbeckensis cause the basioccipital to be much more deeply notched than that of D. motherali.

The phylogenetic placement of D. motherali next to Paluxysuchus newmani Adams, 2013 from the Lower Cretaceous Twin Mountains Formation of Texas is a result of clear similarities; contact between the descending process of the postorbital and the ectopterygoid the jugals which have an anterior ramus that is triangular in cross-section., and enlarged fourth and fifth alveoli suggesting dual pseudocanines in the maxillae. However, the shape of the rostrum is extremely narrow relative to the broad skull table in P. newmani. P. newmani is also distinguished from D. motherali by an anteriorly directed anterolateral process on the postorbital (Adams, 2013). D. motherali has a dorsoventrally oriented protuberance that extends laterally from the postorbital bar. However, this process in both taxa may have formed a similar function as suggested by

Andrade et al. (2011) for the strengthening of the orbit at its posterolateral edge (Adams, 2013).

The close connection between D. motherali and P. newmani also has implications on the

Early to transition of north-central Texas, which has been characterized by

Jacobs and Winkler (1998) as a rapid turnover with little to no overlap between assemblages.

26 The formation of these two north-central Texas taxa into a clade, suggests the early emergence of an endemic crocodyliform assemblage at the beginning of the Late Cretaceous and implies that the transition from the Early to Late Cretaceous may have been more gradual for crocodyliforms

(Adams et al., 2015).

Ecology—Snout shape in crocodylians and their more distant relatives has long been used as an indicator of feeding ecology. Tube-snouted forms have been interpreted as piscivorous (e.g. Iordansky, 1973; Langston, 1973; Busby, 1995) or more broadly as small-prey specialists (McHenry et al., 2006). Blunter, boxier snouts often go hand-in-hand with the anvil- shaped teeth associated with durophagy, and broader, medium-length snouts have been interpreted as a compromise between these two extremes, indicating an ecological generalist

(e.g. Brochu, 2001). Initially, these designations were identified qualitatively (Busby, 1995;

Brochu, 2001), but more recent, quantitative techniques have recovered somewhat similar groupings (Pierce et al., 2008; Sadleir and Makovicky, 2008).

The broad, roughly triangular skull of Deltasuchus falls within the generalist morphotype

(Fig. 3; sensu Brochu, 2001), indicating that this crocodyliform would have fed on a diverse sampling of the other present at the AAS. This stands in contrast to Paluxysuchus, recovered in a sister taxon relationship with Deltasuchus in this analysis, which exhibits a more slender-snouted morphology (Adams, 2013). While size alone is not always the best indicator of trophic status (Drumheller et al., 2014), Deltasuchus was a large bodied crocodyliform, with an estimated total body length of 5.6 to 6.0 meters. Bite marks exhibiting diagnostic crocodyliform features (Njau and Blumenschine, 2006; Drumheller and Brochu, 2014; Drumheller and Brochu,

2016) also have been found on and dinosaurian remains from the AAS (Noto et al., 2012).

Among the largest of these feeding traces is a set of serial marks, consistent with the dentition of

27 the holotype specimen of Deltasuchus in terms of size, shape, and spacing along the tooth row

(Noto et al., 2012). While coprolites consistent in shape with crocodyliform actors also have been recovered from the locality (Main, 2009; Moran et al., 2009; King et al., 2011), modern crocodylian digestion is notoriously destructive (Fisher, 1981), and ongoing research on these trace fossils is not expected to yield much in the way of identifiable remains. For now, the morphology of the specimen, partnered with the associated bite marks, seems to indicate that

Deltasuchus was a top predator in its environment.

CONCLUSIONS

The Arlington Archosaur Site represents one of the most diverse and complete fossil ecosystems known from the middle Cretaceous of Appalachia, providing valuable insight into the floral and faunal dynamics of this time. Little is known about the early development of

Appalachian ecosystems following formation of the Western Interior Seaway. A majority of

Appalachian vertebrate fossil accumulations prior to the Campanian are fragmentary and low diversity. However, discoveries from the AAS and Woodbine Formation of Texas preserve a more complete picture of coastal ecosystems from this poorly known interval. Among the many species recovered, several crocodyliform taxa have been identified, including the large neosuchian Deltasuchus. This broad-snouted, semi-aquatic ambush predator remained ecologically dominant in freshwater aquatic and marginal marine ecosystems through the mid-

Cenomanian. The recovered sister-taxon relationship between D. motherali and Paluxysuchus

28 indicates the early emergence of an endemic crocodyliform assemblage at the beginning of the

Late Cretaceous of Texas.

ACKNOWLEDGEMENTS

We thank the Huffines family and R. Kimball of Johnson Development, who generously provided access to the AAS. Thanks to A. Sahlstein, P. Kirchoff, and B. Walker, who discovered the site. We are grateful to J. Beeck, T. Diamond, R. Fry, S. King, A. Camp, R. Colvin, A.

Sahlstein, B. Carter, P. Scoggins, M. Cohen, D. Summerfelt, A. Miramontes, and the army of dedicated volunteers who helped in excavation and preparation of the material over the years.

Thanks to A. Motheral who discovered the first elements of the holotype. We gratefully acknowledge advice and input from L. Jacobs, A. Fiorillo, R. Tykoski, M. Polcyn, C. Holliday, and C. Brochu. We thank S. W. Salisbury and A. C. Pritchard for their valuable comments that helped improve this manuscript. Access to research collections was possible thanks to K. Morten

(DMNH), D. Winkler (SMU), and M. Brown (TMM). Taxon silhouettes come from Phylopic

(phylopic.org), and were created by P. Buchholz (hadrosauroid), S. Hartman (turtle), Smokeybjb

(crocodyliform), and N. Tamura (lissamphibian). These images are used under a Creative

Commons Attribution-NonCommercial-ShareAlike 3.0 license. This study was supported by funding from the National Geographic Society Conservation Trust Grant #C325-16, as well as the many contributors to our Experiment.com campaign. We dedicate this paper to the memory of D. Main. None of this would have been possible without him.

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Submitted September 16, 2016; accepted DD, YYYY

40 FIGURE 1. A, General Map showing the location of Tarrant and Dallas counties in Texas. B,

Map of Tarrant and Dallas counties, Texas, U.S.A. Arlington Archosaur Site indicated by star.

41 Stippled areas represent surface exposures of the Woodbine Formation. [planned for column width]

FIGURE 2. A, stratigraphic column for the Upper Cretaceous of north-central Texas showing the position of the Woodbine Formation relative to timescale and adjacent geologic units. Stippled intervals represent terrestrial deposits. Arrow indicates position of the Arlington Archosaur Site.

Time scale based on Gradstein et al. (2004). B, Lithologic cross-section of the Arlington

Archosaur Site. Deltasuchus motherali gen. et sp. nov. elements recovered from facies A.

[planned for page width]

42 FIGURE 3. A, articulation of cranial elements of Deltasuchus motherali gen. et sp. nov. in dorsal view. B, reconstruction of the complete skull of D. motherali. Missing elements in gray, based on Paluxysuchus newmani (Adams, 2013). See text for anatomical abbreviations. Scale bar equals 10 cm. [planned for page width]

43 FIGURE 4. Rostrum elements of Deltasuchus motherali gen. et sp. nov., DMNH 2013-07-0001

(holotype). Premaxillae in A, dorsal and B, ventral views; Maxillae in C, dorsal and D, ventral views; E, left nasal in dorsal and ventral views; F, right nasal in dorsal and ventral views

44 (anterior towards top). Open arrows indicate location of prominent notch for 4th dentary pseudocanine. Scale bar equals 4 cm. [planned for page width]

FIGURE 5. Cranial elements of Deltasuchus motherali gen. et sp. nov., DMNH 2013-07-0001

(holotype). Left postorbital in A, dorsal, B, ventral views, black dashed line indicating the margin of orbital fossa on the intertemporal bar of postorbital; C, Posterior view of the

45 articulation of the postorbital and jugal exhibiting the lateral facing boss on the postorbital bar; left jugal, D, lateral, E, medial, and F, dorsal views, raised rim indicated by open-headed arrows, white dotted line indicating v-shaped notch for articulation with lacrimal; right squamosal in G, lateral views (anterior to right). See text for anatomical abbreviations. Scale bar equals 4 cm.

[planned for page width]

46 FIGURE 6. Cranial elements of Deltasuchus motherali gen. et sp. nov., DMNH 2013-07-0001

(holotype). Right quadrate in A, dorsal, B, ventral, C, medial, and D, occipital views. See text for anatomical abbreviations. Scale bar equals 4 cm. [planned for page width]

FIGURE 7. Cranial elements of Deltasuchus motherali gen. et sp. nov., DMNH 2013-07-0001

(holotype). Right otoccipital in A, posterior, B, anterior, and C, ventral, views; left otoccipital

(DMNH 2013-07-0004) in D, posterolateral view; basioccipital in E, lateral, F, posterior, and G, ventral views. Sub-parallel sagittal crests on basioccipital plate indicated by dotted line and open-headed arrows. See text for anatomical abbreviations. Scale bar equals 4 cm. [planned for page width] 47 FIGURE 8. Cranial elements of Deltasuchus motherali gen. et sp. nov., DMNH 2013-07-0001

(holotype). Right ectopterygoid in A, anterior, B, dorsal, and C, posterior views; D, close up view of the articulation of the postorbital, jugal, and ectopterygoid in anterior view; right pterygoid in E, anterior and F, posterior views. See text for anatomical abbreviations. Scale bar equals 4 cm. [planned for page width]

48 FIGURE 9. Lower jaw elements of Deltasuchus motherali gen. et sp. nov., DMNH 2013-07-

0001 (holotype). Right and left dentaries in A, dorsal, B, ventral views; Right dentary in C, medial view; right surangular in D, lateral view; right articular in E, dorsal (anterior to right), F, anterior , and G, lateral views (anterior to right). See text for anatomical abbreviations. Scale bar equals 4 cm. [planned for page width]

49 50 FIGURE 10. A, right dentary teeth 1 and 2 of Deltasuchus motherali gen. et sp. nov., DMNH

2013-07-0001 (holotype). Scale bar equals 1 cm. Isolated crocodyliform teeth from the AAS referred to Deltasuchus motherali gen. et sp. nov. B, DMNH 2014-06-04 in lingual and labial/buccal views. C, DMNH 2013-07-0165 in lingual and labial/buccal views. Scale bar equals 2 cm. [planned for column width]

51 52 FIGURE 11. Phylogenetic placement of Deltasuchus motherali gen. et sp. nov. Strict consensus of 88 equally most parsimonious trees of 1650 steps (CI = 0.241 and RI = 0.671) obtained from a cladistic analysis of 101 taxa and 318 characters. Numbers at each node indicate bootstrap GC values (top number) and Bremer support values (bottom number). Semilunar hash marks indicate stem-based definition and solid circles indicate a node-based taxon. See Turner (2015) for character descriptions. [planned for page width]

53 FIGURE 12. Comparisons of known Woodbine Formation . A, reconstruction of the skull of Deltasuchus motherali; B, reconstruction of the skull of Terminonaris robusta, modified after Wu et al. (2001); reconstruction of the lower jaw of Woodbinesuchus byersmauricei, modified after Lee (1997a). Scale bar equals 10 cm. [planned for page width]

FIGURE 13. Close-up view of narrow groove (white arrow) on the posterior maxillary process of Deltasuchus motherali gen. et sp. nov. (DMNH 2013-07-0001). See text for anatomical abbreviations. Scale bar equals 2 cm. [planned for column width]

APPENDIX 1. Deltasuchus motherali gen. et sp. nov., DMNH 2013-07-0001 was scored and added to the matrix of Turner (2015), which contained 84 taxa and 321 characters. 318 of which are used in the phylogenetic analysis. Scorings for all other taxa used in the analysis along with character descriptions follow Turner (2015). Following Turner (2015), character 5 was excluded from the analysis (due to dependence with the modified definition of character 6) and character 277 was excluded due to doubts of the homology coded for by the character. Character 281 was excluded because it is now interpreted as redundant with character 35. Characters 1, 3, 6, 10, 23, 37, 43–45, 49, 65–67, 69, 73, 77–79, 86, 90–91, 96–97, 104–106, 108, 126, 140–143, 149, 167, 182, 197, and 226 represent potentially nested sets of homologies and/or entail presence and absence information and were set as additive. No additional character modifications were made. Deltasuchus motherali 203?12?1????10?101?????1110?110???0?????????11112011????0010?????1???? ???0???02????????????00?1200??1?3?0200???01??????00???1?1100?0000?0010

54 0110????00???100?0???000??2??1?????0?100??110??00??00?0?00????0??10??0 ?10?00???0???0?0?0?00???000?0000?0???00??1????0????100???01?????0????0 ?????0????0?00?0?????0??0?0?0?0?0???????1

55