'FRANCOSUCHUS' TRAUTHI IS NOT PALEORHINUS: IMPLICATIONS for LATE TRIASSIC VERTEBRATE BIOSTRATIGRAPHY Author(S): RICHARD J

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'FRANCOSUCHUS' TRAUTHI IS NOT PALEORHINUS: IMPLICATIONS FOR LATE TRIASSIC VERTEBRATE BIOSTRATIGRAPHY Author(s): RICHARD J. BUTLER Source: Journal of Vertebrate Paleontology, Vol. 33, No. 4 (July 2013), pp. 858-864 Published by: Taylor & Francis, Ltd. on behalf of The Society of Vertebrate Paleontology Stable URL: https://www.jstor.org/stable/42568654 Accessed: 08-07-2021 12:05 UTC

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This content downloaded from 86.59.13.237 on Thu, 08 Jul 2021 12:05:59 UTC All use subject to https://about.jstor.org/terms Journal of Vertebrate Paleontology 33(4):858- 864, July 2013 © 2013 by the Society of Vertebrate Paleontology

ARTICLE

'FRANCOS U CHUS' TRAUTHI IS NOT PALEORHINUS : IMPLICATIONS FOR LATE TRIASSIC VERTEBRATE BIOSTRATIGRAPHY

RICHARD J. BUTLER GeoBio-Center, Ludwig-Maximilians-Universität München, Richard- Wagner-Straße 10, D-80333 Munich, Germany, [email protected]

ABSTRACT - A rostrum fragment from the marginal marine upper Lunz Formation of Austria (early Late Triassic: late Carnian) was previously identified as a new species of phytosaurian archosauriform, ' Francosuchus' trauthi. ' Francosuchus ' trauthi was subsequently synonymized with the non-phytosaurid phytosaur Paleorhinus , and this synonymy was used as evidence to correlate the ' Paleorhinus biochron' and the Otischalkian land-vertebrate faunachron to the marine timescale. Here, I provide a redescription of ' Francosuchus ' trauthi and document anatomical features that differ substantially from all known species of non-phytosaurid phytosaur. There is no evidence to support synonymy of ' Francosuchus ' trauthi with Paleorhinus , and no unambiguous features to support a phytosaurian identification. However, ' Francosuchus ' trauthi possesses a unique combination of characters that distinguish it from all other Triassic tetrapods, and necessitates referral of the species to a new genus, Dolerosaurus, gen. nov. Rejection of the proposed synonymy between ' Francosuchus ' trauthi and Paleorhinus means that the ' Paleorhinus biochron' cannot be tied to the marine late Carnian as previously suggested, and provides further evidence of the problems inherent in attempting to correlate the terrestrial Triassic to the marine timescale.

INTRODUCTION be diagnosed on the basis of available description and figures (Kuhn, 1933), beyond identification as a non-phytosaurid phy- Phytosaurs are a morphologically distinctive grouptosaur, ofthe super-genus Francosuchus is here considered as a nomen ficially crocodilian-like archosauriform reptiles currently dubium (Stocker known and Butler, 2013). almost exclusively from Late Triassic deposits but Hunt with and a Lucasnear- (1991) proposed a biostratigraphic zone, the global distribution (e.g., Camp, 1930; Ballew, 1989; 4 Paleorhinus Buffetaut, biochron,' based upon the proposed shared pres- 1993; Long and Murry, 1995; Hungerbühler, 2002; ence Stocker, of Paleorhinus! 2010; Parasuchus in strata in North America, cen- Brusatte et al., 2013; Stocker and Butler, 2013). tralThe Europe,stratigraph- Morocco, and India. Hunt and Lucas (1991) consid- ically oldest and phylogenetically earliest-branching ered the phytosaurs holotype specimen of 4 Francosuchus ' trauthi (NHMW include the North American Paleorhinus bransoni and ' Pale- 1905/0007/0052) as a specifically indeterminate specimen refer- orhinus ' scurriensis (Lees, 1907; Long and Murry, 1995; Stocker, able to Paleorhinus. NHMW 1905/0007/0052 was collected from 2010), ' Francosuchus ' angustifrons and Ebrachosuchus neukami marginal marine strata (marls of the Opponitzer Limestone of from southern Germany (Kuhn, 1933, 1936), Parasuchus thehislopi upper Lunz Formation) that have been assigned a late Car- from India (Chatterjee, 1978), ' Paleorhinus ' magnoculus nianfrom (Tuvalian) age using palynomorphs and ammonites (Dunay Morocco (Dutuit, 1977a), and an unnamed species from Polandand Fisher, 1978; Hunt and Lucas, 1991; Pott et al., 2007); on this (Dzik, 2001). These early phytosaurs are placed outside ofbasis, the Hunt and Lucas (1991) assigned a late Carnian (Tuvalian) clade Phytosauridae (Doyle and Sues, 1995; Stocker, 2010), age and to their 4 Paleorhinus biochron.' retain external nares that are located anterior to (rather than Subsequentdor- work by Lucas (1998, 2010) on Late Triassic ver- sal or posterior to) the antorbital fossa. On this basis, all of tebrate these biostratigraphy has proposed that the first appearance of non-phytosaurid phytosaur species have been synonymized Paleorhinus! by Parasuchus can be used to define the Otischalkian some authors within either the genus Paleorhinus or the land-vertebrate genus faunachron (LVF), and has continued to use Parasuchus (e.g., Hunt and Lucas, 1991; Lucas et al., 2007). NHMW 1905/0007/0052 as evidence that this biostratigraphic Huene (1939) described and named a new fossil reptile species, zone can be correlated with the Tuvalian (see also Lucas and identified by him as an early phytosaur, based upon a fragmen- Heckert, 2000). However, other workers have considered this tary rostrum (NHMW 1905/0007/0052) that had been collected broad conception of Paleorhinus! Parasuchus to be potentially or in 1905 by the famous paleoentomologist Anton Handlirsch probably near paraphyletic (e.g., Hungerbühler, 2001a; Wroblewski, Lunz am See (district of Scheibbs, Lower Austria [Niederöstere- 2003; Parker and Irmis, 2006; Stocker, 2010), and have strongly ich]) in Austria. Huene (1939) assigned the new species tocriticized the the use of long-range vertebrate biostratigraphy in the genus Francosuchus , as Francosuchus trauthi. The genus Franco-terrestrial Triassic (e.g., Rayfield et al., 2005, 2009; Irmis et al., suchus was originally described based upon a phytosaur 2010).speci- Moreover, Hungerbühler (2001b), Langer (2005), Ray- men from the Late Triassic locality of Ebrach in southern field Ger- et al. (2009), and Irmis et al. (2010) all considered NHMW many (Kuhn, 1933, 1936), approximately 400 km distant 1905/0007/0052from to represent an indeterminate non-phytosaurid Lunz am See. Unfortunately, the holotype of the type speciesphytosaur, in which case the specimen is of limited use for bios- of Francosuchus , Francosuchus broilii Kuhn, 1933, was destroyed tratigraphic purposes. along with most of the Ebrach collections during bombing of Although the the taxonomie affinities of NHMW 1905/0007/0052 Bayerische Staatssammlung für Paläontologie und Geologie have in been discussed by multiple authors (Hunt and Lucas, 1991; Munich during World War II. Because the type species cannotHungerbühler, 2001b; Rayfield et al., 2005, 2009; Irmis et al.,

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2010), the specimen itself has not received "Partial phytosaurfurther snout description from . . . Opponitzer Schichten"; Ray- since the work of Huene (1939), and all fieldsubsequent et al., 2009:84. workers have accepted Huene's referral of the specimen "cf. Francosuchus to Phytosauria. trauthi "; Irmis etHere, al., 2010:41. I provide a redescription of NHMW 1905/0007/0052 and demonstrate that it cannot be assigned to Paleorhinus Holotype - NHMW , and 1905/0007/0052, in fact dif- corresponding to the old inventory number NHMW 1905 VII 52 (incorrectly listed as fers sufficiently from known members of Phytosauria that its re- 1905/13 by Hunt and Lucas, 1991), fragment of rostrum (Huene, ferral to this clade must be considered questionable. Moreover, NHMW 1905/0007/0052 possesses a unique 1939:fig. combination 1; Westphal, 1976:fig. of 7E).char- Casts of the specimen are available in the Palaeontological Collection of the University acters not present in any other Triassic tetrapod, requiring the of Tübingen, Germany (unnumbered specimens), and the New erection of a new genus for the species ' Francosuchus ' trauthi. I Mexico Museum of Natural History and Science, Albuquerque, discuss the implications of this reidentification for Late Triassic U.S.A. (NMMNH P-12960; see Hunt and Lucas, 1991). terrestrial biostratigraphy. Institutional Abbreviations - BSPG, Bayerische Diagnosis - Differs Staatssamm- from all other Late Triassic tetrapods, in- lung für Paläontologie und Geologie, cluding Munich, known species Germany; of Phytosauria, on the basis of a unique NHMW, Naturhistorisches Museum Wien, Vienna, Austria; combination of characters. Similar to some non-phytosaurid phy- ZPAL, Institute of Paleobiology, Polish Academy of Sciences, tosaurs including Paleorhinus and askeptosaurid thalattosauri- Warsaw, Poland. forms but differing from most other Late Triassic tetrapods in possessing external nares that are non-terminal in position (also in ichthyosaurs), prenarial rostrum strongly compressed dorsoventrally (at least twice as wide mediolaterally as MATERIALS AND METHODS deep dorsoventrally), and prenarial rostrum elongate and near NHMW 1905/0007/0052 was scanned by computed parallel-sided tomogra- in dorsal view. Differs from all known phytosaurs phy (CT) at the Institut für Paläontologie of the including University Paleorhinus of in the following features: rostrum is not Vienna using a SkyScan 1173 micro-CT scanner substantially with a voltageexpanded dorsoventrally at the level of the exter- of 130 kV and current of 61 /xA, and a voxel nal size nares of relative 32 дт. to the prenarial region; pneumatic paranasal Micro-CT data were reconstructed using Skyscan sinus NRecon within the soft- prenarial rostrum absent; alveolar neurovascu- ware. For comparative CT data, the holotypes oflar canalsEbrachosuchus positioned medially close to midline within prenarial neukami (BSPG 1931 X 501) and ' Francosuchus rostrum, ' angustifrons rather than laterally; alveolar ridges absent; and alveoli (BSPG 1931 X 502) were scanned using a Siemens not defined medical by sharpCT rims on palatal surface. Differs from known scanner at Klinikum rechts der Isar (Munich). non-phytosaurid CT data (image phytosaurs including Paleorhinus in the posses- stacks) and associated full metadata (scan settings) sion of foranterior NHMW margins of choanae placed immediately ventral 1905/0007/0052 are reposited at NHMW and thoseto the anteriorfor BSPG margins of external nares, and from phytosaurid 1931 X 501 and BSPG 1931 X 502 at BSPG. CT data were ex- phytosaurs in possessing external nares placed anterior to the an- amined as DICOM image stacks using freeware OsiriX, torbital ImageJ, fenestra (assuming that the fenestra was present). Differs and 3D Slicer software on a Mac OS X operating system. from askeptosaurid thalattosauriforms and ichthyosaurs in that A cast of NHMW 1905/0007/0052 was also loaned from the the transverse width of each external naris is approximately equal Palaeontological Collection of the University of Tübingen, to the Ger- transverse width of the internarial bar and in the possession many, in order to make direct comparisons with phytosaur of strongly speci- developed ornamentation on the rostrum. mens held at the BSPG. Locality and Horizon - Construction tunnel of the second Vi- enna water pipeline ('Lunzbergstollen der II Wiener Wasser- leitung'), Lunz am See, Scheibbs, Lower Austria, Austria, ap- SYSTEMATIC PALEONTOLOGY proximately 100 km west of Vienna. Marls of the Opponitzer Limestone of the upper Lunz Formation (Late Triassic, Tu- DIAPSIDA Osborn, 1903 valian). The locality has been entered into The Paleobiology DIAPSIDA incertae sedis Database and is collection number 97854. DOLEROSAURUS , gen. nov.

Diagnosis - As for the type species, by monotypy (see below). Type Species - Dolerosaurus trauthi (Huene, 1939). DESCRIPTION Etymology - From the Ancient Greek SoXspóç ('doleros-') NHMW 1905/0007/0052 is a portion of the rostrum (Figs. 1, and aavpoç ('-sauros'), meaning 'deceptive reptile,' referring to 2B, C, E) measuring 113 mm in maximum preserved anteropos- the original and likely erroneous identification of the type species terior length, and is 31 mm wide at its broken anterior extremity as a Paleorhinus- like non-phytosaurid phytosaur, which has un- and 57 mm wide at its broken posterior extremity. The anterior fortunately lead to misleading biostratigraphic interpretations. margins of the external nares are preserved posterodorsally, and DOLEROSAURUS TRAUTHI (Huene, 1939), comb. thenov. anterior margins of the choanae are present posteroventrally. (Figs. 1-3) The specimen's external (dorsal and lateral) surfaces are covered with ornamentation (Fig. 1A, D), which takes the form of fine "cf. Francosuchus trauthi n. sp."; Huene, 1939:144. linear striations (extending anteroposteriorly, subparallel to one "gen. nov.? cf. Francosuchus trauthi (von Huene)"; another), Kuhn, low anteroposteriorly extending ridges, and tiny, low 1939:281. discrete nodes. "cf. Francosuchus trauthi Huene"; Trauth, 1948:90. The rostrum is strongly dorsoventrally compressed (Fig. IB), "?P. (F.) trauthi Huene, 1939"; Westphal, 1976:109. although crushing is not evident; at its broken anterior extrem- " Paleorhinus sp."; Hunt and Lucas, 1991:495. ity, the rostrum is 15 mm deep and thus twice as broad as deep. " Paleorhinus ( =Francosuchus )"; Lucas and Heckert, 2000:27. Its dorsal surface is gently convex mediolaterally. In dorsal view, "Snout fragment from the lower Opponitzer Beds"; the rostrum is almost parallel-sided along much of its preserved Hungerbühler, 2001b:99. length (Fig. 1 A), but expands markedly toward the posterior end, " Francosuchus trauthi "; Langer, 2005:226, 233. with this expansion beginning immediately anterior to the ex- " Francosuchus ? trauthi "; Rayfield et al., 2005:337. ternal nares. In lateral view, the rostrum becomes only slightly

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FIGURE 1. NHMW 1905/0007/0052, holotype of Dolerosaurus trauthi (Huene, 1939). Partial rostrum in dorsal (A), anterior (B), ventral (C), and right lateral (D) views. Arrows point to anterior end of specimen. Abbreviations: alv, alveoli; cho, choanae; en, external nares.

deeper towards its posterior end (Fig. ID), with maxillae. the posterior In a few cases end (e.g., sixth alveolus on the right side), being 135% of the depth of the anterior end. theOn alveoli the externalappear to besur- empty, but in others the root of a func- face, no sutures are readily identifiable (Fig. 1 tional A, D), tooth and or the a replacement iden- tooth is preserved (confirmed by tifications of the positions of elements made CTby data; Huene Fig. (1939;3A-C). Fully e.g., erupted functional teeth are missing of the premaxilla, maxilla, 'septomaxilla,' nasal) in all cases.cannot The bealveoli con- are broadly spaced from one another (in firmed. The anterior margins of the external some nares cases, aresuch roundedas between alveoli 4 and 5 on the left side, the in dorsal view (Fig. 1A). In their preserved portions,spacing between the adjacent exter- alveoli is greater than the length of the nal nares are each approximately 10 mm wide. individual Only the alveoli; anterior- Fig. 1С), and in ventral view the lateral margin most portion of the internarial bar is preserved. of the Its rostrum dorsal appears surface slightly scalloped (Fig. 1С). is flattened and the bar is relatively broad (13 CT mmdata (Fig.wide) 3) reveal with that tooth roots are set deeply within near parallel sides in dorsal view (Fig. 1A). In the cross-section, alveoli (thecodont the implantation), and have an oval cross- bar is approximately 8.5 mm deep. The presence section (longer or absence anteroposteriorly of than transversely) with a small 'septomaxillae' cannot be determined due to pulpthe cavityabsence that of also clear has an oval outline. The roots are angled sutural contacts. posterodorsally away from the oral margin and are curved along Ventrally, the alveoli are poorly demarcated and not defined their length (Fig. 3C). The roots are generally surrounded not by by sharp bony rims (Fig. 1С), although the specimen does sediment, not but by a narrow area of dense mineralization (appear- appear to have suffered extensive weathering or postmortem ing dis- white in CT cross-sections; Fig. ЗА, В), which is of variable tortion. There are six alveoli present on the ventral surface thickness. on It seems likely that this reflects taphonomic replace- the left side and seven on the right, although only the most poste-ment of soft tissues rather than bone of attachment, given that rior part of the first alveolus on the right side is preserved. Basedsimilar mineralization appears to have occurred in areas identi- upon the sutures identified on the palate (see below), it appears fied here as probable sutures (see below). A replacement tooth likely that all of these preserved alveoli are positioned within (fourth the alveolus on the right side) has a crown that is recurved

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FIGURE 2. Comparison of rostral region of skull of BSPG 1931 X 502, holotype of ' Francosuchus' angustifrons Kuhn, 1936 (A, D, F), with NHMW 1905/0007/0052, holotype of Dolerosaurus trauthi (Huene, 1939) (B, C, E). Dorsal (A, B), palatal (C, D), and right lateral (E, F) views. The two specimens are shown to scale, and with the anterior margins of the external nares placed level with one another. Large bold arrows indicate the approximate position of the anterior margins of the choanae; note that in BSPG 1931 X 502 the choanae are set far posterior to the anterior margins of the external nares. Abbreviations: alvr, alveolar ridge; antf, antorbital fenestra; cho, choanae; exn, external nares.

and transversely compressed, tapering Asto itsnoted apex by in Huene lateral (1939), view the choanae are placed immediately (Fig. 3C). Replacement teeth are visible inventral other to the externalseveral nares. tooth positions, and are positioned either entirely within the base of the root of the tooth they are replacing (alveolus 7 on the COMPARISONS right side) or immediately posterior and slightly medial to the root (alveolus 5 on both left and right sides; Fig. 3C), NHMW which 1905/0007/0052 is partially shows some re- similarities to non- sorbed by the replacement tooth. Each phytosaurid tooth socket phytosaurs appears such asto Ebrachosuchus neukami (BSPG have a pocket-like connection at its base 1931 to X 501)one andof ' aFrancosuchus pair of (of- ' angustifrons (BSPG 1931 X 502), ten interconnected) narrow and irregularly as originally shaped noted canals by Huenethat ex-(1939). NHMW 1905/0007/0052, tend through the midline of the rostrum, BSPG just 1931 dorsal X 501, toand midheight BSPG 1931 X 502 are all broadly sim- (Fig. ЗА, В). These canals presumably represent ilar in size (transverse the alveolar width neu-across anterior margin of external rovascular canals, which contained in life nares: the NHMW alveolar 1905/0007/0052 nerves, = 54 mm;ar- BSPG 1931 X 501 = teries, and veins. 55 mm; BSPG 1931 X 502 = 43 mm). Moreover, all three pos- The ventral surface of the palate between sess non-terminal the externalalveoli nares is and flat a prenarial rostrum that is to slightly convex anteriorly (Fig. 1С), strongly and becomesdorsoventrally gently compressed, con- being at least twice as wide cave posteriorly (immediately anterior as dorsoventrallyto the choanae). deep (Fig. Sutures 2). BSPG 1931 X 501 and BSPG are difficult to discern with certainty. 1931 Huene X 502 are (1939) more strongly identified dorsoventrally a compressed than median groove as the interpremaxillary NHMW suture, 1905/0007/0052, and two but flanking these former two specimens have grooves as the contacts between the premaxillae undergone at least andsome dorsoventralthe maxil- crushing. lae; these grooves are visible as thin white However, lines thereof dense are a number mineral- of striking differences in ization in the CT sections, and likely do morphology indeed representbetween NHMW sutures. 1905/0007/0052 and all known It cannot be conclusively determined ifnon-phytosaurid parts of phytosaurs.the vomers A key difference are is that in NHMW present anterior to the choanae, as shown 1905/0007/0052 by Huene the anterior (1939). margins The of the choanae are placed bar between the choanae has broken directlyaway, ventral so the to the choanae anterior margins ap- of the external nares, pear as a single opening with a width suchof thatapproximately the airway is short and20 vertically mm. directed (Figs. 1, 2).

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FIGURE 3. CT data for NHMW 1905/0007/0052, holotype of Dolerosaurus trauthi (Huene, 1939) (A-C), and BSPG 1931 X 502, holotype of ' Fran - cosuchus ' angustifrons Kuhn, 1936 (D). (А, В) Transverse sections through the rostrum of NHMW 1905/0007/0052, approximately 25 mm (A) and 45 mm (B) anterior to the external nares. (С) Longitudinal section through the rostrum of NHMW 1905/0007/0052, showing the right dentition. (D) Transverse section through the rostrum of BSPG 1931 X 502, approximately 25 mm anterior to the external nares (more anteriorly placed sections are not possible due to breakage of the rostrum). Abbreviations: alv, alveolus; alvr, alveolar ridge; alv.lt4, empty alveolus in left tooth position 4; md.si, median pneumatic sinus; nvc, neurovascular canal; rt, replacement tooth; rt.r4, rt.r5, replacement tooth in right tooth positions 4 and 5; t.It3, tooth in left tooth position 3; t.r5, tooth in right tooth position 5.

By contrast, in all known non-phytosaurid phytosaur an extensive specimens, median cavity within the rostrum that is positioned the anterior margins of the choanae are set far anterior posteriorly to, and to thecontinuous with, the airway (Fig. ЗА, В). This external nares, resulting in a horizontally directed cavity in airway phytosaurs that represents a pneumatic paranasal sinus that is separated from the oral cavity by a short likely secondary housed palatediverticula of the antorbital air sinuses, possibly as formed by the premaxillae, maxillae, and vomers. an adaptation For example, to resisting torsion (Witmer, 1997), and has been in ' Francosuchus' angustifrons (BSPG 1931 Xdocumented 502), the anterior in a broad range of phytosaur species (Camp, 1930; margins of the choanae are set approximately Witmer, 65 mm 1997), posterior including the non-phytosaurid phytosaurs Ebra- to the anterior margins of the external nares, chosuchus and approximately neukami (BSPG 1931 X 501) and ' Francosuchus' an- 25 mm posterior to the posterior margins of gustifrons the external (BSPG nares 1931 X 502), in which the paranasal sinus forms (Fig. 2). The anterior margins of the choanae most of of BSPG the volume1931 X of the rostrum immediately anterior to the ex- 502 thus lie directly medial to the anterior ternalmargins nares of the(Fig. an- 3D). In NHMW 1905/0007/0052, CT data show torbital fossae and substantially posterior to that the theexternal rostrum nares. is largely solid, with the exception of the alveoli A similar configuration to that of 4 Francosuchus' and paired angustifrons and relatively narrow alveolar neurovascular canals is present in the non-phytosaurid phytosaurs (Fig. Ebrachosuchus ЗА, В). These canals are positioned in a much more median neukami (BSPG 1931 X 501), Parasuchus hislopiposition (Chatterjee, in NHMW 1905/0007/0052 than are the paired lateral 1978), ' Paleorhinus' scurriensis (TTU P-00539), canals thatPaleorhinus are present in phytosaurs and that are often contin- bransoni (Lees, 1907), ' Paleorhinus ' magnoculus uous (Dutuit,with the 1977a), paranasal sinus (Fig. 3D). and the Krasiejów phytosaur (ZPAL Ab III Several 200; other Dzik, features 2001). differentiate NHMW 1905/0007/0052 In phytosaurid phytosaurs, in which the from external phytosaurs, nares particularly are non-phytosaurid phytosaurs. In more posteriorly positioned dorsal to the antorbital lateral view fossa,of the rostrum,the there is almost no elevation of the anterior margins of the external nares do lie external directly nares above, relative orto the dorsal margin of the prenarial even posterior to, the anterior margins of region the choanae(Fig. 2E). This(e.g., contrasts strongly with the condition in Camp, 1930; Dutuit, 1977b; Stocker, 2010). allHowever, phytosaurs, NHMW including non-phytosaurid phytosaurs, in which 1905/0007/0052 clearly differs from phytosaurid the external phytosaurs nares are elevated in such that the rostrum is at least that the external nares must have been positioned twice as deep anterior along the anterior part of the external nares to the antorbital fenestrae, assuming that antorbital as along the fenestraeprenarial region (e.g., BSPG 1931 X 501, BSPG were indeed present (they may not have been, 1931 Xshould 502, in bothNHMW of which the depth of the rostrum at the 1905/0007/0052 prove to represent a non-archosauriform anterior margin taxon).of the external nares is 200% of the depth of the Another key difference from both non-phytosaurid prenarial region; and Camp, phy- 1930; Chatterjee, 1978; Long and Murry, tosaurid phytosaurs is the absence in NHMW 1995; 1905/0007/0052 Dzik, 2001; Hungerbühler, of 2002; Stocker, 2010; Fig. 2F).

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Alveolar or 'palatal' ridges are absent along the ventral CONCLUSIONS surface of NHMW 1905/0007/0052 (Fig. 1С), but are present in virtually Descriptive data presented here demonstrate that NHMW all other phytosaurs, including non-phytosaurid phytosaurs (e.g., 1905/0007/0052, the holotype of Dolerosaurus trauthi , cannot be ' Francosuchus" angustifrons, BSPG 1931 X 502; Hungerbühler, referred to the phytosaurian genus Paleorhinus , and cannot be re- 2002; Stocker, 2010; Fig. 2D, F), with the exception of Ebra- ferred with confidence to Phytosauria. If NHMW 1905/0007/0052 chosuchus neukami (BSPG 1931 X 501), in which the ridges does ultimately prove referable to Phytosauria, it likely rep- are developed only along parts of the palate and only as subtle resents a previously unknown lineage, morphologically distinct thickenings. Finally, the alveoli lack sharply defined rims in from Paleorhinus and all other phytosaurs. As a result, NHMW NHMW 1905/0007/0052 and thereby differ from the typically 1905/0007/0052 is irrelevant to ongoing debate focusing on ver- well-defined alveoli of those non-phytosaurid phytosaurs that are tebrate biostratigraphy and LVFs in the terrestrial Triassic, and of similar absolute size to NHMW 1905/0007/0052 (e.g., BSPG cannot and should not be employed as evidence to correlate ei- 1931 X 501, BSPG 1931 X 502; Fig. 2D). ther the Otischalkian LVF or the 4 Paleorhinus biochron' to the In light of the substantial differences between NHMW marine realm (contra Hunt and Lucas, 1991; Lucas, 1998, 2010; 1905/0007/0052 and all non-phytosaurid phytosaurs, including the see also Irmis et al., 2010). These results provide further evidence position of the choanae directly beneath the external nares, the of the problems inherent in attempting to correlate the terrestrial absence of a paranasal sinus, the lack of elevation of the external Triassic to the marine timescale (Langer, 2005; Rayfield et al., nares, the absence of palatal ridges, and the poor definition of the 2005, 2009; Irmis et al., 2010). alveoli, referral of this specimen to Paleorhinus is unsupported and can be confidently rejected. Previous referral of this specimen to Paleorhinus was based solely on the inferred ACKNOWLEDGMENTS position of the nares anterior to the antorbital fossa This (Hunt work andwas supportedLucas, 1991). by a DFG Emmy Noether Pro- However, as pointed out by other authors (e.g., Rayfield et al., gramme award (BU 2587/3-1). I thank U. Göhlich (NHMW) and 2009; Irmis et al., 2010; Stocker, 2010), the anterior position of P. Havlik (University of Tübingen) for access to specimens in the nares is a phytosaurian plesiomorphy and cannot be used to their care, R. Stepanek (University of Vienna) and M. Dobritz support an identification of the specimen as Paleorhinus , even if (Klinikum rechts der Isar, Munich) for CT scanning, and S. Laut- the specimen can be confidently identified as phytosaurian. How- enschlager for assistance with CT data. С. Kammerer provided ever, there are no features of NHMW 1905/0007/0052 that unam- invaluable assistance with etymological matters, suggesting the biguously support a referral of the specimen to Phytosauria as op- new generic name used here. This work benefited from discus- posed to another tetrapod clade (elongation sions with of M.the Jones, rostrum/non- M. Stocker, R. Bronowicz, O. Rauhut, P. terminal nares are also present in a number of other marine rep- Barrett, J. Müller, and T. Scheyer. The review comments of M. tile groups; see below), meaning that even identification of the Stocker and W. Parker and the editorial work of R. Irmis helped specimen as an indeterminate phytosaur is questionable. Some anatomical features of NHMW 1905/0007/0052 show improve the final version of the manuscript. similarities to groups of marine diapsids already known from the non-terrestrial Late Triassic of central Europe. For example, an LITERATURE CITED elongated rostrum and non-terminal nares are also present Ballew, in K. L. 1989. A phylogenetic analysis of Phytosauria from the Late ichthyosaurs, although an ichthyosaur identity appears unlikely Triassic of the western United States; pp. 309-339 in S. G. Lucas and given that Triassic ichythosaurs typically have rostra that lack A. or- P. Hunt (eds.), Dawn of the Age of Dinosaurs in the American namentation and taper markedly in dorsoventral height anteri- Southwest. 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