PaleoBios 35: 1–8, December 22, 2018 PaleoBios OFFICIAL PUBLICATION OF THE UNIVERSITY OF CALIFORNIA MUSEUM OF PALEONTOLOGY pap pap as fo as ca ca A B C fo aap amr fo aap amr pap aap aap fo amr D E F ca as as ca aap pap amr pap fo fo fo amr G H I ca as ca as ADAM D. MARSH (2018). A new record of Dromomeron romeri Irmis et al., 2007 (Lagerpetidae) from the Chinle Formation of Arizona, U.S.A. Cover: Figure 2 illustrating distal tarsals of dinosauromorphs from the Triassic of Arizona, U.S.A. Citation: Marsh, A.D. 2018. A new record of Dromomeron romeri Irmis et al., 2007 (Lagerpetidae) from the Chinle Forma- tion of Arizona, U.S.A. PaleoBios, 35. ucmp_paleobios_42075. A new record of Dromomeron romeri Irmis et al., 2007 (Lagerpetidae) from the Chinle Formation of Arizona, U.S.A. ADAM D. MARSH Petrified [email protected] National Park, 1 Park Road #2217 Petrified Forest National Park, AZ 86028 The relatively recent discovery and contextualization of silesaurid and lagerpetid dinosauromorphs has led to a revolution in understanding the early evolutionary history of the dinosaurian lineage. Lagerpetids areDromomeron known from gregorii North America and South America in Middle and Upper Triassic rocks, especially the Chinle Formation of New Mexico and the Dockum Group of Texas. Until now, only a single specimen of on Ward Terrace in thewas Navajo known Nation from of the Arizona Upper is Triassic referred Chinle to Dromomeron Formation ofromeri. Arizona. MNA However, V7237 reprea new- lagerpetidsents the youngest astragalus radioisotopically-dated specimen (MNA V7237) record from theof Lagerpetidae, Owl Rock Member indicating of the that Chinle D. Formationromeri persisted found Keywords:throughout Upperthe entire Triassic, Norian Chinle (Otischalkian Formation, into Dinosauromorpha, the Apachean) in Lagerpetidae, North America. Dromomeron INTRODUCTION et al. 2009a, 2010, Nesbitt 2011, Nesbitt and Ezcurra Historically, interpretations of the vertebrate assem- 2015, , Baron and Williams 2018). More blages within the Upper Triassic Chinle Formation of profoundly, discoveries at exceptionally well-sampled Arizona emphasized a diverse group of ‘thecodontians,’ NorianMarsh sites suchet al. 2016as the Hayden Quarry at Ghost Ranch, now a paraphyletic group comprising pseudosuchian New Mexico show that non-dinosaur dinosauromorphs archosaurs (aetosaurs) and non-archosaur archosauro- not only co-occurred with their dinosaurian relatives, but morphs (phytosaurs), with only two coeval representa- also may have been more diverse ( , Irmis tive dinosaur groups (herrerasaurids and coelophysoids) et al. 2007, Nesbitt et al. 2009b) (Fig. 1) . This includes (e.g., Camp 1930, Colbert 1947, 1989, Long and Murry the Lagerpetidae , a cladeEzcurra of non-dinosau 2006 - 1995). However, more recent discoveries of dinosaurs riform dinosauromorphs that comprises Lagerpeton and non-dinosaur dinosauromorphs (e.g., Irmis et al. chanarensis Romer,Arcucci, 1971 from1986 the Chañares Formation 2007a, Nesbitt et al., 2009a, 2009b, Nesbitt and Ezcurra, of Argentina (Sereno and Arcucci 1994a), an unnamed 2015, Lessner et al., 2018) from the southwestern United taxon from the Ischigualasto Formation (Martinez et States have cast more light on the diversity of Dinosauro- al. 2012), Ixalerpeton polesinensis morpha Benton, 1985 and its early evolutionary history from the Santa Maria Formation of Brazil, and three up to the end-Triassic extinction. species within the genus DromomeronCabreira Irmis et al.,al., 20072016: The alpha taxonomy of coelophysoids within the D. romeri Irmis et al., 2007 and D. gregorii Nesbitt et al., Chinle Formation and other Upper Triassic sedimentary 2009a - Arizona, New Mexico, and Texas, and D. gigas Martinez stood, and the presence of herrerasaurids in the Upper from fromthe Chinle the Quebrada Formation del and Barro Dockum Formation Group of Triassicrocks in ofwestern North AmericaNorth America is now isdoubted still not based well underon the Brazil. A lagerpetid referred to D. romeri is present in the reinterpretation of holotype specimens and a more Chinleet al., 2016 Formation of the Eagle Basin in Colorado (Small comprehensive understanding of the suite of character 2009, Small and Martz 2013). Hypothetical relationships states that diagnose avemetatarsalian clades (Nesbitt L. chanarensis and within Lagerpetidae generally reflect Citation: Marsh, A.D. 2018. A new record of Dromomeron romeri Irmis et al., 2007 (Lagerpetidae) from the Chinle Formation of Arizona, U.S.A. PaleoBios, 35. ucmp_paleobios_42075. Permalink: https://escholarship.org/uc/item/8w5755sg Copyright: Items in eScholarship are protected by copyright, with all rights reserved, unless otherwise indicated. 2 PALEOBIOS, VOLUME 35, DECEMBER 2018 Age (Ma) 203 A Garza County, B Ghost Ranch, NM Randall County, TX 204 northern AZ RHAETIAN Apachean 205 MNA composite Argtentina 206 795 1000 km (C) 207 upper Eagle Basin, CO Owl Rock Member 208 * ‘siltstone’ member 209 210 SQ Chinle Formation * DMNH QdP 692 211 QdP, ASRH, VP H3 Chinle Formation 212 ‘red siltstone’ member Petrified Forest Member Revueltian * Formation del Barro Quebrada BR 213 Petrified Forest Member * middle 214 MOTT 3898 DMNH 692 215 * Formation Canyon Cooper Poleo Ss 216 NORIAN 217 CMNA 795 H3, Sonsela Member SQ 218 * UCMP A269 lSC MOTT 219 3624 MOTT 3898, * MOTT 3624, Chinle Formation UCMP southern Brazil MOTT 2000/ MOTT 3869 220 A269 TMM 31100 * 500 km Adamanian 221 Howard County, TX lower 222 223 * lSC Blue Mesa Member 224 225 * MOTT 2000/ MOTT TMM 31100 3869 226 * 227 City Formation Colorado 228 * Mesa Redondo Member 229 Formation Caturrita D Boren RanchBoren sandstones PVSJ 883 Otischalkian 230 Ischigualasto Formation Ischigualasto 231 * VP 232 Los CARNIAN Rastros Fm 233 Moenkopi Formation * BR 234 * 235 236 other lagerpetids ~ * ASRH Chanares Formation Chanares 237 Santa Maria Formation Figure 1. See caption on top of page 3. MARSH—DROMOMERON ROMERI FROM THE CHINLE FORMATION OF ARIZONA, USA 3 Figure 1. Relative stratigraphic locations of fossil localities. A. Adapted from Riggs et al. 2003, Martz 2008, Irmis et al. 2011, Ra- mezani et al. 2011, 2014, Martinez et al. 2012, Mariscano et al. 2015, , Ezcurra et al. 2017, , Langer et al. 2018, Lessner et al. 2018). B, C. Geographic distribution of lagerpetids. D. Hypothetical relationships within Lager- petidae from Müller et al. (2018 Sarigül 2016 Martz and Parker 2017 of lagerpetid specimens. Tan color represents the Navajo Nation. Silhouette of Dromomeron by Nobu Tamura, used under the Cre- ). Asterisks indicate radiometrichttp://creativecommons.org/licenses/by-sa/3.0/ dates, and silhouettes indicate approximate stratigraphic position ativeAbbreviations Commons: Attribution-ShareAlikeASRH, A.S.R. Hill; BR, Buriol 3.0 Unported ravine; H3license ([ lSC, lower Sunday Canyon; QdP, Quebrada]). Vector del maps Puma; of SQNorth, Snyder America, Quarry; Central VP, ValleAmerica, Pintado. and South America were used from [FreeVectorMaps.com]; Materials and Methods for full links. , Hayden quarry #3; I. polesonensis as early members of the Lagerpetidae, the (Fig. 1A, C). Preparation of this material was accom- Dromomeron clade being more derived with respect to plished with “airscribe and carbon needle” in addition the unnamed taxon from the Ischigualasto Formation Kirby 1991, p. (Langer et al. 2017, Nesbitt et al. 2017, Müller et al. 2018) 32). The lagerpetid specimen from MNA 795 (see below) (Fig. 1D). Stratigraphic and geographic locations of these wasto unknown found with adhesives unionid and bivalves consolidants (Antediplodon ( cf. cris- lagerpetids are shown in Fig. 1. tonensis [ , MNA N9282), partial paramedian With the exception of a referred specimen from the osteoderms of the aetosaur, Typothorax coccinarum Cope, Placerias Quarry near St. Johns, Arizona, the fossil record 1875 (e.g.,Meek MNA 1875] V5583), and pseudopalatine phytosaur of lagerpetids from the Chinle Formation of Arizona squamosals (e.g., MNA V7143). Much of the collection is depauperate compared to the Chinle Formation in - New Mexico, where the Hayden Quarry at Ghost Ranch tifying Ornithischia Seeley, 1887, Rauisuchidae Huene, D. romeri, and 1942,from this Postosuchus locality includes Chatterjee, field 1985 and ,collection or Sphenosuchidae tags iden the nearby Snyder Quarry also preserves a Dromom- Huene, 1942, but an apomorphy-based approach to iden- eronpreserves astragalocalcaneum associated skeletal (Irmis remains et al. of2007, Nesbitt et Bell et al. 2004, Nesbitt et al., 2007, Nesbitt al. 2009b, Smith et al. 2018) (Fig. 1). Described here is , Bell et al. 2010) can only constrain a new specimen of Lagerpetidae referable to D. romeri mosttification of these ( specimens to the level of Archosauria from the Chinle Formation of Arizona at Ward Terrace and Stocker, except2008 for partial shuvosaurid limb bones Member on Ward Terrace may represent the youngest Cope, 1869 - on the Navajo Nation. The specimen from the Owl Rock ers(e.g., upon MNA request. V5615). More precise locality information is provides further evidence for the long and geographically repositedVector mapsat MNA of andNorth is availableAmerica, toCentral qualified America, research and spreadknown lagerpetidstratigraphic in North range America, of the lagerpetid if not worldwide, fossil record. and South America were used from [https://freevectormaps. Institutional abbreviations—DMNH, Denver Mu- com/world-maps/north-america/WRLD-NA-01-0002 seum of Natural History, Denver, Colorado; GR, Ruth [https://freevectormaps.com/world-maps/central-amer-