Nodosaurids are poorly known from the Lower Cretaceous of Europe. Two associated ankylosaur skeletons excavated from the lower Albian carbonaceous member of the Escucha Formation near Ariño in northeastern Teruel, Spain reveal nearly all the diagnostic recognized character that define nodosaurid ankylosaurs. These new specimens comprise a new genus and species of nodosaurid ankylosaur and represent the single most complete taxon of ankylosaur from the Cretaceous of Europe. These two specimens were examined and compared to all other known ankylosaurs. Comparisons of these specimens document that Europelta carbonensis n. gen., n. sp. is a nodosaur and is the sister taxon to the Late Cretaceous nodosaurids Anoplosaurus, Hungarosaurus, and Struthiosaurus, defining a monophyletic clade of European nodosaurids– the Struthiosaurinae.

Funding: This study is part of the paleontology research projects of Departamento de Educación, Universidad, Cultura y Deporte, Gobierno de Aragón and has been supported by its Dirección General de Patrimonio Cultural (exp. 201/2010, 201/10-2011, 201/10-11-2011), DINOSARAGÓN CGL2009-07792 R&D project (Ministerio de Ciencia e Innovación and FEDER Funds), FOCONTUR (Grupo de Investigación Consolidado E-62, Departamento de Industria e Innovación Ciencia, Tecnología y Universidad, Gobierno de Aragón), Instituto Aragonés de Fomento, Fundación SAMCA, and Fundación Conjunto Paleontológico de Teruel-Dinópolis. Partial funding for this project was provided by Craig Wilkerson through the Utah Friends of Paleontology. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

The two associated ankylosaur skeletons described herein were separated by 200 meters. The location of the holotype AR-1/10 ( Fig. 5 ) was still available for examination and sampling for microfossils in December of 2011 [58] , while that of the paratype AR-1/31 ( Fig. 6 ) was already inaccessible.

The bonebed was located many tens of meters underground prior to strip mining operations in the Santa María coal mine. As mining operations proceed, more of the plant debris stratum containing the bonebed is exposed as simultaneous reclamation covers the previously exposed surface. Thus, with the help of mine managers, efficient methodologies for the documentation and extraction of significant fossils have been established [42] . By the end of 2012, an area of approximately 25 ha had been investigated and the areal distributions of 101 vertebrate concentrations were documented; 33 of these consisted of associated dinosaur skeletons (mostly iguanodonts) and 68 consisted of other vertebrate remains (mostly turtles and crocodilians). During this stage of the project, numerous dinosaurs (ornithischian elements and associated skeletons, and saurischian teeth), two types of turtle, crocodilians, fish (both ostheicthyians and selachiens), coprolites, molluscs (freshwater bivalves and gastropods), arthropods (ostracods), and abundant plant remains (logs, plant fragments, palynomorphs, and amber) have been excavated.

Caudal vertebra AR-1-3616/31 in (A) lateral view showing damage to the bone from the growth of gypsum crystals. Maxillary tooth AR-1-424/10 in (B) labial view and (C) lingual views showing diagenetic damage to teeth. Skull of type of Europelta carbonensis n. gen., n. sp., AR-1-544/10 (D) as exposed in AR-1/10 and (E) X-ray image in dorso-ventral orientation. Light patches are areas of pyrite mineralization.

The bonebed is located immediately below the lowest mineable coal seam in the Santa María coal mine ( Fig. 2 ), in a dark olive-gray to olive-black mudstone that preserves a high percentage of fossil plant debris. In overall appearance, the rock is much like the plant debris beds in the Wessex Formation on the Isle of Wight [59] , [60] and, as in those beds, there is a great amount of pyrite (iron sulfide) disseminated through the matrix and in the fossils. Significant amounts of iron sulfide in the coals were found to decrease up section, away from marine and brackish-water environments. In addition to this depositional relationship, it has been speculated that detrital evaporites from exposed Triassic strata on the north and northwest sides of the basin have secondarily contributed significant amounts of sulfur to these coals [43] , [61] . Additionally, the abundance of pyrite in the bones indicates that the long-term stability of the fossils is in question as pyrite breaks down in an expansive oxidation reaction that liberates corrosive sulfuric acid compounds that cannot be reversed [62] . The degradation by this pyrite is apparent on most of the bones soon after exposure to the surface. This is indicated by the rapid appearance of fine, powdery to crystalline gypsum coating bones and teeth, and by the expansion and shattering of some bones and teeth with internal gypsum formation ( Fig. 4 ). Protocols are being developed to ensure the preservation of the primary data represented by these important fossils [42] , [62] .

A sample of the matrix from the bonebed was processed for both palynomorphs and calcareous microfossils. The palynomorphs were exclusively of terrestrial origin and indicated an Albian age (Gerry Waanders, 2012, personal communication). The microfossils consisted exclusively of freshwater ostracods and charophytes. The ostracods represent new species and the charophytes are also reported from the Albian of Tunisia [58] . No arenaceous foraminifera were identified, which, along with the absence of dinoflagelates, indicates that the bonebed formed well inland of marine and brackish water influences ( Fig. 3 ).

The geologic age of the Escucha Formation has been considered to be early to middle Albian. It overlies Aptian strata in central basinal settings and is, in turn, overlain by the upper Albian Utrillas Formation [44] . However, both calcareous plankton (foraminifera and nanoplankton) [54] and palynomorphs [55] , [56] indicate that the lower Escucha Formation is late Aptian in age. Both fresh and brackish coal-bearing strata are recognized below the regional unconformity within the Escucha [43] . However, reports on the microplankton restrict marine and marginal marine facies to the late Aptian in the lower Escucha Formation [54] – [56] . Marine ostracods have been reported from the upper Escucha Formation northeast of Teruel that confirm an Albian age for the upper portion of these strata in this area [57] .

(A) General Lower Cretaceous stratigraphy in the area of the Oliete sub-basin with the relative distribution of thyreophoran dinosaurs in Spain and southern England indicated. (B) General stratigraphy of the Escucha Fm. in the area around Ariño, Aragón, Spain showing approximate position of dinosaur locality AR-1. Stratigraphic nomenclature following Rodríguez-López and others [53] .

Counterclockwise rotation of the Iberian Plate toward the end of the Early Cretaceous resulted in the development of a series of syndepositional sub-basins bounded by active faults within Ebro Basin south of the Pyrenean ranges, northeast of the Iberian Range, and northwest of the Catalan/Coastal Range [44] , [45] . The new dinosaur locality is within the Oliete sub-basin on the northwest margin of the Escucha outcrop belt [42] , [44] . The Formación Lignitos de Escucha and overlying Formación Arenas de Utrillas were initially described in 1971 [46] . These largely Albian-aged strata were deposited along the northwestern margin of the Tethys Sea during the fragmentation of this terrain, and overlie Aptian strata in the center of each sub-basin and unconformably overlie progressively older strata toward their margins. Initially, the Escucha Formation was divided into three members [47] and interpreted to be an unconformity-bounded lower to middle Albian depositional sequence, representing a progradational, tidally-dominated delta sequence [44] , [48] – [52] . Recently, the upper “fluvial” member has been reinterpreted as an eolian depositional sequence separated from the underlying portions of the Escucha Formation by a regional unconformity [53] . We recognize this bipartite division of the Escucha Formation ( Fig. 2 ).

The earliest reported dinosaur remains from Spain were found in the Escucha Formation, few significant vertebrate fossils had been recovered from these rocks in the 140 intervening years [41] , [42] . Current research on vertebrate sites in the Escucha Formation in the northern Teruel Province in the Community of Aragón, Spain, by the Fundación Conjunto Paleontológico of Teruel-Dinópolis has resulted in the discovery of an extensive new dinosaur locality in the open-pit Santa María coal mine near Ariño ( Fig. 1 ) operated by Sociedad Anónima Minera Catalano-Aragonesa (SAMCA Group) [42] . The most abundant dinosaur identified is a distinctive iguanodontian ornithopod recently described as Proa valdearinnoensis [43] . Among the many other significant fossils excavated are two associated partial skeletons of a new species of ankylosaur, described herein as Europelta carbonensis n. gen., n. sp. This new taxon is the most completely known ankylosaur in Europe and adds considerable new information about Early Cretaceous ankylosaurian phylogeny and biogeography.

Northeastern Spain has contributed many dinosaur discoveries from both Lower and Upper Cretaceous strata in recent years [35] . The Early Cretaceous dinosaurs discovered to date include numerous sauropods, iguanodonts, and ankylosaurs from the Barremian-lower Aptian, with all the fragmentary ankylosaur material assigned tentatively to the genus Polacanthus [25] , [28] , [36] – [40] . All the Late Cretaceous ankylosaurs from Spain have in turn been assigned to Struthiosaurus [28] – [30] .

Only nodosaurids have been described from the Upper Cretaceous of Europe with Struthiosaurus austriacus described from the Campanian of Austria in 1871 [19] – [24] followed by Struthiosaurus transylvanicus [25] , [26] , [27] from the uppermost Cretaceous (upper Maastrichtian) strata of Romania. Until recently, all Late Cretaceous ankylosaur fossils in Europe have been assigned to Struthiosaurus [28] – [30] including Struthiosaurus languedocensis from the Campanian of southern France [31] . The primitive nodosaurid Hungarosaurus tormai [32] , [33] from the mid-Late Cretaceous (Santonian) is now known from multiple specimens and has become the best documented ankylosaur in Europe.

Ankylosaurs were first described from the Lower Cretaceous of England with Hylaeosaurus armatus (Valanginian) described in 1833 [1] – [3] . Hylaeosaurus is one of the three dinosaurs on which the Dinosauria were defined [4] and one of the first dinosaurs for which a full-sized life reconstruction was attempted at the Crystal Palace Park in London in 1854 [5] . Although first mentioned in an anonymous article in the September 16 th 1865 issue of the “The Illustrated London News” by Sir Richard Owen [6] , the Early Cretaceous (Barremian) Polacanthus was not described formally as Polacanthus foxii by Hulke until 1882 [7] – [10] . The abundant plates and spines of these ankylosaurs are characteristic of the Lower Cretaceous up into the lower part of the Aptian stage [11] , [12] . In 1867, Huxley described the fragmentary Acanthopholis from the base of the Upper Cretaceous (Cenomanian) [13] – [15] . Additionally, in 1879, Seeley [16] described the juvenile nodosaurid Anoplosaurus curtonotus [17] from the uppermost Lower Cretaceous (upper Albian) Cambridge Greensand. Subsequent descriptions of the fragmentary remains of ankylosaurs from the Early Cretaceous of Europe have been tentatively assigned to the genus Polacanthus [18] .

Asian ankylosaur material researched include an adult skull of Tsagantegia longicranialis (MPC 100/1306), China, Pinacosaurus grangeri (AMNH 6523) and three undescribed skulls personally excavated by JIK from the Djadokhta Formation, Shabarakh Usu (Flaming Cliffs, Mongolia) and housed at MAS, Talarurus plicatospineus (composite skeleton made up of parts of many individuals assigned to PIN 557), cast skull of Saichania chulsanensis (PIN 3141/251), a relatively complete specimen referred to Saichania with in situ armor but lacking its skull (MPC 100/1305), Tarchia gigantea (PIN 3142/250), a cast skull of Minotaurasaurus ramachandrani (INBR 21004), and a cast skeleton of Crichtonsaurus benxiensis housed in the Museum at the Chaoyang Bird National Geopark, Liaoning.

Early Cretaceous polacanthine ankylosaur material examined includes Polacanthus foxii (NHMUK R 175, 9293), Hylaeosaurus armatus (NHMUK R 3775), Hoplitosaurus marshi (USNM 4752), and the extensive material of Gastonia burgei material housed at the Prehistoric Museum (including holotype CEUM 1307 and paratype material), and cranial material from a minimum of six individuals at Brigham Young University's Earth Science Museum, together with the postcranial skeleton of an unnamed new species of polacanthine (BYU 245).

In addition to accessing the ever-expanding ankylosaur literature, the senior and third authors have had the opportunity to study firsthand much of the important ankylosaur material collected globally. From the basal thyreophorans: the type material of Scutellosaurus lawleri (MNA P1.175), the type material of Scelidosaurus harrisoni (NHMUK R 1111), and a large, exceptionally well-preserved, articulated Scelidosaurus specimen with intact armor, collected and owned by David Sole and currently exhibited at the University of Bristol. Also, a full cast of the left side of the skeleton (SGDS 1311) exhibited in southwestern Utah was examined.

AMNH , American Museum of Natural History, New York, New York, NHMUK , Natural History Museum, London, England, CEUM , Prehistoric Museum, Utah State University, Price, Utah, DMNH , Denver Museum of Nature and Science, Denver, Colorado, MPC , Geological Institute, Ulaan Bataar, Mongolia, FCPTD/MAP , Fundación Conjunto Paleontológico de Teruel-Dinópolis/Museo Aragonés de Paleontología, Teruel, Spain, FMNH , Field Museum of Natural History, Chicago, MPC , Institute of Geology, Mongolian Academy of Sciences, Ulaan Baatar, Mongolia; INBR , Victor Valley Museum, Apple Valley, California, IVPP , Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China, KUVP , Kansas Museum of Natural History, Lawrence, Kansas, MPC , Mongolian Paleontological Center, Ulaan Baatar, Mongolia; MNA , Museum of Northern Arizona, Flagstaff, Arizona, NMC , National Museum of Canada, Ottawa, Canada, NMW , National Museum of Wales, Cardiff, England, PIN , National Institute of Paleontology, Moscow, Russia, QM , Queensland Museum, Queensland, Australia, ROM , Royal Ontario Museum, Toronto, Canada, SDNHM , San Diego Natural History Museum, San Diego, California, SGDS , Saint George Dinosaur Discovery Site at Johnson Farm, St. George, Utah, SMP , State Museum of Pennsylvania, Harrisburg, Pennsylvania, SMU , Schuler Museum, Southern Methodist University, Dallas, Texas, USNM , National Museum of Natural History, Smithsonian Institution, Washington D.C.

We do not refer to the “armor” on the skull roof as caputegulae, as we consider these patterns in the Nodosauridae to reflect impressions of scale boundaries on the skull roof as opposed to thickened remodeled cranial bone. We use the term caudal rib instead of caudal transverse process. We employ the monophyletic clade Polacanthidae of Carpenter [63] to facilitate comparison with and discussion of a number of similar taxa (Gargoyleosaurus, Mymoorapelta, Hylaeosaurus, Polacanthus, Hoplitosaurus, and Gastonia). The most recent analysis of polacanthids as a monophylogenetic subfamily of nodosaurids was by Yang and others [64] , who similarly defined them as the most inclusive clade containing Polacanthus foxii but not Ankylosaurus magniventris or Panoplosaurus mirus.

The electronic edition of this article conforms to the requirements of the amended International Code of Zoological Nomenclature, and hence the new names contained herein are available under that Code from the electronic edition of this article. This published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the ICZN. The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix “ http://zoobank.org/ ”. The LSID for this publication is: urn:lsid:zoobank.org:pub:9246FFA7-6271-4734-8E01-5590BE4A80C2. The LSID for Europelta carbonensis is: urn:lsid:zoobank.org:act:089040A3-1BCF-42D1-B99F-94840E2BB96D. The electronic edition of this work was published in a journal with an ISSN (1932-6203), and has been archived and is available from the following digital repositories: LOCKSS ( http://www.lockss.org ); PubMed Central ( http://www.ncbi.nlm.nih.gov/pmc ).

All of the specimens described in this paper (AR-1/10 and AR-1/31) are reposited in the collections of the Fundación Conjunto Paleontológico de Teruel-Dinópolis/Museo Aragonés de Paleontología (FCPTD/MAP). Locality information is available from the registrar of the museum as per museum policy. All necessary permits were obtained for the described study, which complied with all relevant regulations. All of these specimens were collected under permits obtained from the Sociedad Anónima Minera Catalano-Aragonesa.

The quadrate is shorter and mediolaterally wider than in any other ankylosaur. The posterior margin of the skull is concave in dorsal view. The sacrum is arched dorsally about 55° in lateral view. The pubis is fully and uniquely fused to the ischium with a slot-shaped foramen between the post-pubic process and the position of the pubic peduncle forming an ischiopubis. The tibia is longer relative to the length of the femur (90%) than in other ankylosaurs for which these proportions are known. Laterally compresed, flanged osteoderm with a flat plate-like base is present anteriorly on the pelvic shield.

Elsewhere, the Escucha Formation has been interpreted as late Aptian to early Albian in age based on nanofossils, planktonic foraminifera, dinoflagellates and palynomorphs [50] , [52] . An analysis of the palynomorphs, ostracods, and charophytes from AR-1 indicates that the site is completely of early Albian age [57] .

The type locality, Fundación Conjunto Paleontológico of Teruel-Dinópolis locality AR-1, is located east of Ariño, Teruel Province, Spain. The fossil horizon is below the lowest mineable coal seam at Sociedad Anónima Minera Catalano-Aragonesa Group's Ariño coal mine in a plant debris bed in the lower Escucha Formation [42] . The paratype AR-1/31 was located 200 m laterally from the holotype AR-1/10 in the same bed. Pyrite is common within the bone and the surrounding sediment of the bonebed, common also in plant debris beds in the older Wessex Formation on the Isle of Wight [58] .

AR-1/31, a partial skeleton deposited at Fundación Conjunto Paleontológico de Teruel-Dinópolis/Museo Aragonés de Paleontología (FCPTD/MAP). The paratype consists of a partial left jaw with dentary and surangular (AR-1-3698) and isolated angular (AR-1-2945), 10 teeth (AR-1-3432, AR-1-3495, AR-1-3524, AR-1-3650, AR-1-3699 to AR-1-3701, AR-1-3705, AR-1-3706, AR-1-3961), five cervical vertebrae (AR-1-3586, AR-1-3632, AR-1-3657, AR-1-3671, AR-1-3676), nine dorsal vertebrae (AR-1-3489, AR-1-3586, AR-1-3633, AR-1-3662, AR-1-3672 to 3675, AR-1-3677, AR-1-3704), three to four? dorsosacral vertebrae (AR-1-3450, AR-1-3451), a sacrum (AR-1-3446), a caudosacral vertebra (AR-1-3512), two sacral rib fragments (AR-1-3452, AR-1-3460), 14 caudal vertebrae (AR-1-2950, AR-1-3204, AR-1-3206, AR-1-3243, AR-1-3265, AR-1-3348, AR-1-3398, AR-1-3478, AR-1-3615, AR-1-3616, AR-1-3714 to 3717), a right ilium (AR-1-3490), two left ilium fragments (AR-1-3521, AR-1-3571), two ischia with fused pubes (AR-1-3648, AR-1-3649), a right femur (AR-1-3244), a right tibia (AR-1-3237), a right fibula (AR-1-3238), a calcaneum (AR-1-3239), four metatarsals (AR-1-3100, AR-1-3173, AR-1-3233, AR-1-3234), eight phalanges (AR-1-3032, AR-1-3066, AR-1-3174, AR-1-3179, AR-1-3324, AR-1-3234, AR-1-3292, AR-1-3356), nine unguals (AR-1-2952, AR-1-2986, AR-1-3172, AR-1-3181, AR-1-3182, AR-1-3288, AR-1-3291, AR-1-3386, AR-1-3711), and 90 osteoderms (AR-1-3024, AR-1-3030, AR-1-3074 to AR-1-3076, AR-1-3080, AR-1-3145, AR-1-3159, AR-1-3180, AR-1-3207 to AR-1-3209, AR-1-3216, AR-1-3223, AR-1-3226 to AR-1-3229, AR-1-3292, AR-1-3236, AR-1-3242, AR-1-3338 to AR-1-3340, AR-1-3390, AR-1-3438, AR-1-3447 to AR-1-3449, AR-1-3491, AR-1-3492, AR-1-3494, AR-1-3506, AR-1-3540, AR-1-3572 to AR-1-3576, AR-1-3587, AR-1-3588, AR-1-3590, AR-1-3597, AR-1-3598, AR-1-3608 to AR-1-3613, AR-1-3638, AR-1-3658, AR-1-3680 to AR-1-3684, AR-1-3687, AR-1-3708, AR-1-3720, AR-1-3721, AR-1-3932 to AR-1-3960).

AR-1/10, a disarticulated partial skeleton reposited at Fundación Conjunto Paleontológico de Teruel-Dinópolis/Museo Aragonés de Paleontología (FCPTD/MAP). The holotype consists of: a mostly complete skull (AR-1-544), isolated left and right nasals (AR-1-133, and AR-1-639), a dentary fragment (AR-1-362), 15 isolated teeth (AR-1-323 to AR-1-325, AR-1-343, AR-1-358, AR-1-417, AR-1-418, AR-1-423, AR-1-424, AR-1-428, AR-1-454, AR-1-482, AR-1-563, AR-1-564 and AR-1-567), an atlas (AR-1-649), five cervical vertebrae (AR-1-431, AR-1-449, AR-1-533, AR-1-637, AR-1-650), two cervical ribs (AR-1-450, AR-1-4452), AR-1-638 (possibly the first dorsal vertebrae), seven more posterior dorsal vertebrae (AR-1-154, AR-1-155, AR-1-322, AR-1-430, AR-1-448, AR-1-478, AR-1-535, AR-1-556), a section of synsacrum (AR-1-154), three isolated dorsal ribs (AR-1-331, AR-1-333, AR-1-476), seven dorsal rib fragments (AR-1-339, AR-1-341, AR-1-427, AR-1-534, AR-1-641, AR-1-642, AR-1-676), three caudal vertebrae (AR-1-562, AR-1-635, AR-1-636), four chevrons (AR-1-560, AR-1-561, AR-1-569, AR-1-4451), a coracoid with a small portion of scapula (AR-1-657), a scapular blade fragment (AR-1-429), two xiphosternal plates (AR-1-252, AR-1-4675), two partial humeri (AR-1-327, AR-1-655), a right ilium-ischium-pubis (AR-1-479), a left ischium-pubis (AR-1-129), and 70 osteoderms (AR-1-126 to AR-1-128, AR-1-192, AR-1-234, AR-1-241, AR-1-246, AR-1-247, AR-1-272, AR-1-276, AR-1-438, AR-1-444, AR-1-447, AR-1-461, AR-1-462, AR-1-464, AR-1-467, AR-1-472, AR-1-496 to AR-1-530, AR-1-553, AR-1-651 to AR-1-653, AR-1-659, AR-1-675, AR-1-4450, AR-1-4454 to AR-1-4463).

Skeletal reconstruction in: (A) lateral view with unknown parts of the skeleton shaded in gray, (B) lateral view with hypothetical distribution of the armor indicated, and (C) dorsal view with hypothetical distribution of the armor on right side of body indicated.

Interstitial ossicle AR-1-3933/31 in: (A) external view and (B) basal view. Interstitial ossicle AR-1-3934/31 in: (C) external view and (D) basal view. Interstitial ossicle AR-1-3935/31 in: (E) external view and (F) basal view. Interstitial ossicle AR-1-3936/31 in: (G) external view and (H) basal view. Interstitial ossicle AR-1-3937/31 in: (I) external view and (J) basal view. Interstitial ossicle AR-1-3958/31 in: (K) external view and (L) basal view. Interstitial ossicle AR-1-3938/31 in: (M) external view and (N) basal view. Interstitial ossicle AR-1-3939/31 in: (O) external view and (P) basal view. Interstitial ossicle AR-1-3940/31 in: (Q) external view and (R) basal view. Interstitial ossicle AR-1-/313941 in: (S) external view and (T) basal view. Interstitial ossicle AR-1-3959/31 in: (U) external view and (V) basal view. Interstitial ossicle AR-1-3942/31 in: (W) external view and (X) basal view. Interstitial ossicle AR-1-3943/31 in: (Y) external view and (Z) basal view. Interstitial ossicle AR-1-3944/31 in: (AA) external view and (BB) basal view. Interstitial ossicle AR-1-3945/31 in: (CC) external view and (DD) basal view. Interstitial ossicle AR-1-3946/31 in: (EE) external view and (FF) basal view. Interstitial ossicle AR-1-3076/31 in: (GG) external view and (HH) basal view. Interstitial ossicle AR-1-3947/31 in: (II) external view and (JJ) basal view. Interstitial ossicle AR-1-3948/31 in: (KK) external view and (LL) basal view. Interstitial ossicle AR-1-3949/31 in: (MM) external view and (NN) basal view. Interstitial ossicle AR-1-3950/31 in: (OO) external view and (PP) basal view. Interstitial ossicle AR-1-3957/31 in: (QQ) external view and (RR) basal view. Interstitial ossicle AR-1-3951/31 in: (SS) external view and (TT) basal view. Interstitial ossicle AR-1-3952/31 in: (UU) external view and (VV) basal view. Interstitial ossicle AR-1-3953/31 in: (WW) external view and (XX) basal view. Interstitial ossicle AR-1-3956/31 in: (YY) external view and (ZZ) basal view. Interstitial ossicle AR-1-3960/31 in: (AAA) external view and (BBB) basal view.

AR-1/10. Interstitial ossicle AR-1-497/10 in: (A) external view and (B) basal view. Interstitial ossicle AR-1-498/10 in: (C) external view and (D) basal view. Interstitial ossicle AR-1-499/10 in: (E) external view and (F) basal view. Interstitial ossicle AR-1-500/10 in: (G) external view and (H) basal view. Interstitial ossicle AR-1-501/10 in: (I) external view and (J) basal view. Interstitial ossicle AR-1-502/10 in: (K) external view and (L) basal view. Interstitial ossicle AR-1-503/10 in: (M) external view and (N) basal view. Interstitial ossicle AR-1-504/10 in: (O) external view and (P) basal view. Interstitial ossicle AR-1-505/10 in: (Q) external view and (R) basal view. Interstitial ossicle AR-1-506/10 in: (S) external view and (T) basal view. Interstitial ossicle AR-1-507/10 in: (U) external view and (V) basal view. Interstitial ossicle AR-1-508/10 in: (W) external view and (X) basal view. Interstitial ossicle AR-1-509/10 in: (Y) external view and (Z) basal view. Interstitial ossicle AR-1-510/10 in: (AA) external view and (BB) basal view. Interstitial ossicle AR-1-511/10 in: (CC) external view and (DD) basal view. Interstitial ossicle AR-1-512/10 in: (EE) external view and (FF) basal view. Interstitial ossicle AR-1-513/10 in: (GG) external view and (HH) basal view. Interstitial ossicle AR-1-514/10 in: (II) external view and (JJ) basal view. Interstitial ossicle AR-1-515/10 in: (KK) external view and (LL) basal view. Interstitial ossicle AR-1-516/10 in: (MM) external view and (NN) basal view. Interstitial ossicle AR-1-517/10 in: (OO) external view and (PP) basal view. Interstitial ossicle AR-1-518/10 in: (QQ) external view and (RR) basal view. Interstitial ossicle AR-1-519/10 in: (SS) external view and (TT) basal view. Interstitial ossicle AR-1-520/10 in: (UU) external view and (VV) basal view. Interstitial ossicle AR-1-521/10 in: (WW) external view and (XX) basal view. Interstitial ossicle AR-1-522/10 in: (YY) external view and (ZZ) basal view. Interstitial ossicle AR-1-4454/10 in: (AAA) external view and (BBB) basal view. Interstitial ossicle AR-1-523/10 in: (CCC) external view and (DDD) basal view. Interstitial ossicle AR-1-524/10 in: (EEE) external view and (FFF) basal view. Interstitial ossicle AR-1-525/10 in: (GGG) external view and (HHH) basal view. Interstitial ossicle AR-1-526/10 in: (III) external view and (JJJ) basal view. Interstitial ossicle AR-1-527/10 in: (KKK) external view and (LLL) basal view. Interstitial ossicle AR-1-528/10 in: (MMM) external view and (NNN) basal view. Interstitial ossicle AR-1-529/10 in: (OOO) external view and (PPP) basal view. Interstitial ossicle AR-1-530/10 in: (QQQ) external view and (RRR) basal view. Interstitial ossicle AR-1-4459/10 in: (SSS) external view and (TTT) basal view. Interstitial ossicle AR-1-4455/10 in: (UUU) external view and (VVV) basal view. Interstitial ossicle AR-1-4460/10 in: (WWW) external view and (XXX) basal view. Interstitial ossicle AR-1-4456/10 in: (YYY) external view and (ZZZ) basal view. Interstitial ossicle AR-1-4461/10 in: (AAAA) external view and (BBBB) basal view. Interstitial ossicle AR-1-4457/10 in: (CCCC) external view and (DDDD) basal view. Interstitial ossicle AR-1-4462/10 in: (EEEE) external view and (FFFF) basal view. Interstitial ossicle AR-1-4458/10 in: (GGGG) external view and (HHHH) basal view. Interstitial ossicle AR-1-4463/10 in: (IIII) external view and (JJJJ) basal view.

Type D-E armor AR-1-3024/10 in: (A) external view and (B) basal view. Type D-E armor AR-1-3145/10 in: (C) external view and (D) basal view. Type D-E armor AR-1-3229/10 in: (E) external view and (F) basal view. Type E armor AR-1-3588/31 in: (G) external view and (H) basal view. Type D-E armor AR-1-3207/31 in: (I) external view and (J) basal view. Type E armor AR-1-3216/31 in: (K) external view and (L) basal view. Type E armor AR-1-3242/31 in: (M) external view and (N) basal view. Type E armor AR-1-3208/31 in: (O) external view and (P) basal view. Type E armor AR-1-3494/31 in: (Q) external view and (R) basal view. Type E armor AR-1-3612/31 in: (S) external view and (T) basal view. Type E armor AR-1-3598/31 in: (U) external view and (V) basal view. Type E armor AR-1-3338/31 in: (W) external view and (X) basal view. Type E armor AR-1-3932/31 in: (Y) external view and (Z) basal view. Type E armor AR-1-3611/31 in: (AA) external view and (BB) basal view. Type E armor AR-1-3227/31 in: (CC) external view and (DD) basal view. Type E armor AR-1-3613/31 in: (EE) external view and (FF) basal view. Deeply excavated osteoderm AR-1-3292/31 in: (GG) external view and (HH) basal view. Deeply excavated osteoderm AR-1-3721/31 in: (II) external view and (JJ) basal view.

Type C armor AR-1-3449/31 in: (A) external view and (B) basal view. Type C armor AR-1-3608/31 in: (C) external view and (D) basal view. Type B-C armor AR-1-3491/31 in: (E) external view and (F) basal view. Type B-C armor AR-1-3492/31 in: (G) external view and (H) basal view. Type D armor AR-1-3590/31 in: (I) external view and (J) basal view. Type D armor AR-1-3587/31 in: (K) external view and (L) basal view. Type D armor AR-1-3438/31 in: (M) external view and (N) basal view. Type D armor AR-1-3390/31 in: (O) external view and (P) basal view. Type D armor AR-1-3030/31 in: (Q) external view and (R) basal view. Type D armor AR-1-3209/31 in: (S) external view and (T) basal view. Type D-F armor AR-1-3572/31 in: (U) external view and (V) basal view. Type F armor AR-1-3681/31 in: (W) external view and (X) basal view. Type F armor AR-1-3340/31 in: (Y) external view and (Z) basal view. Type F armor AR-1-3448/31 in: (AA) external view and (BB) basal view. Type F armor AR-1-3228/31 in: (CC) external view and (DD) basal view. Type F armor AR-1-3447/31 in: (EE) external view and (FF) basal view. Type F armor AR-1-3226/31 in: (GG) external view and (HH) basal view. Type F armor AR-1-3080/31 in: (II) external view and (JJ) basal view. Type F armor AR-1-3576/31 in: (KK) external view and (LL) basal view. Type F armor AR-1-3638/31 in: (MM) external view and (NN) basal view. Type F armor AR-1-3658/31 in: (OO) external view and (PP) basal view. Type F armor AR-1-3683/31 in: (QQ) external view and (RR) basal view. Type F armor AR-1-3573/31 in: (SS) external view (TT) and basal view. Type F armor AR-1-3574/31 in: (UU) external view and (VV) basal view. Type F armor AR-1-3597/31 in: (WW) external view and (XX) basal view. Type F armor AR-1-3610/31 in: (YY) external view and (ZZ) basal view. Type F armor AR-1-3682/31 in: (AAA) external view and (BBB) basal view. Type F armor AR-1-3339/31 in: (CCC) external view and (DDD) basal view. Type F armor AR-1-3180/31 in: (EEE) external view and (FFF) basal view. Type F armor AR-1-3687/31 in: (GGG) external view and (HHH) basal view. Type F armor AR-1-3609/31 in: (III) external view and (JJJ) basal view. Type F armor AR-1-3680/31 in: (KKK) external view and (LLL) basal view. Type F armor AR-1-3684/31 in: (MMM) external view and (NNN) basal view. Small type D armor AR-1-3575/31 in: (OOO) external view and (PPP) basal view. Type F armor AR-1-3074/31 in: (QQQ) external view and (RRR) basal view. Type F armor AR-1-3708/31 in: (SSS) external view and (TTT) basal view. Type F armor AR-1-3720/31 in: (UUU) external view and (VVV) basal view.

Type C armor AR-1-467/10 in: (A) external view and (B) basal view. Type C armor AR-1-127/10 in: (C) external view and (D) basal view. Type C-D armor AR-1-461/10 in: (E) external view and (F) basal view. Type C-D armor AR-1-652/10 in: (G) external view and (H) basal view. Type D armor AR-1-553/10 in: (I) external view and (J) basal view (J). Type D armor AR-1-464/10 in: (K) external view and (L) basal view. Type C armor AR-1-4450/10 in: (M) external view and (N) basal view. Type B-C armor AR-1-462/10 in: (O) external view and (P) basal view. Type E armor AR-1-472/10 in: (Q) external view and (R) basal view. Type D-E armor AR-1-651/10 in: (S) external view and (T) basal view. Type F armor AR-1-234/10 in: (U) external view and (V) basal view. Type F armor AR-1-241/10 in: (W) external view and (X) basal view. Type F armor AR-1-659/10 in: (Y) external view and (Z) basal view. Type G armor AR-1-192/10 in: (AA) external view and (BB) basal view. Irregular armor mass AR-1-447/10 in: (CC) lateral view, (DD) external view, (EE) lateral oblique view, and (FF) basal view. Small type F armor AR-1-247/10 in: (GG) external view and (HH) basal view. Small type F armor AR-1-126/10 in: (II) external view and (JJ) basal view. Small type F armor AR-1-496/10 in: (KK) external view and (LL) basal view. Small type F armor AR-1-246/10 in: (MM) external view and (NN) basal view. Small osteoderm AR-1-438/10 in: (OO) external view and (PP) basal view.

Metatarsal AR-1-3100/31 in: (A) distal view, (B) anterior view, (C) right lateral view, (D) posterior view, (E) left lateral view, and (F) proximal view. Metatarsal AR-1-3234/31 in: (G) distal view, (H) anterior view, (I) right lateral view, (J) posterior view, (K) left lateral view, and (L) proximal view (L). Metatarsal AR-1-3233/31 in: (M) distal view, (N) anterior view, (O) right lateral view, (P) posterior view, (Q) left lateral view, and (R) proximal view. Possible proximal metatarsal AR-1-3173/31 in: (S) anterior view, (T) right lateral view, (U) posterior view, (V) left lateral view, and (W) anterior view. Proximal phalanx AR-1-3324/31 in: (X) right lateral view, (Y) posterior view, (Z) left lateral view, and (AA) proximal view. Medial phalanx AR-1-3174/31 in: (BB) distal view, (CC) right lateral view, (DD) posterior view, (EE) left lateral view, and (FF) proximal view. Medial phalanx AR-1-3066/31 in: (GG) distal view, (HH) right lateral view, and (II) proximal view. Medial phalanx AR-1-3032/31 in: (JJ) distal view, (KK) anterior view, (LL) right lateral view, (MM) posterior view, (NN) left lateral view, and (OO) proximal view. Distal phalanx AR-1-3292/31 in: (PP) distal view, (QQ) anterior view, (RR) right lateral view, (SS) posterior view, (TT) left lateral view, and (UU) proximal view. Distal phalanx AR-1-3356/31 in: (VV) distal view, (WW) anterior view, (XX) right lateral view, (YY) posterior view, and (ZZ) proximal view. Distal phalanx AR-10-3179/31 in: (AAA) distal view, (BBB) anterior view, (CCC) right lateral view, (DDD) posterior view, (EEE) left lateral view, and (FFF) proximal view. Distal phalanx AR-1-3224/31 in: (GGG) anterior view, (HHH) right lateral view, (III) posterior view, and (JJJ) left lateral view. Pedal ungual AR-1-3172/31 in: (KKK) left lateral view, (LLL) dorsal view, (MMM) right lateral view, (NNN) ventral view, and (OOO) proximal view. Pedal ungual AR-1-3181/31 in: (PPP) right lateral view, (QQQ) dorsal view, (RRR) right lateral view, (SSS) ventral view, and (TTT) proximal view. Pedal ungual AR-1-2952/31 in: (UUU) left lateral view, (VVV) dorsal view, (WWW) right lateral view, (XXX) ventral view, and (YYY) proximal view. Pedal ungual AR-1-3291/31 in: (ZZZ) left lateral view, (AAAA) dorsal view, (BBBB) right lateral view, (CCCC) ventral view, and (DDDD) proximal view. Pedal ungual AR-1-3288/31 in: (EEEE) left lateral view, (FFFF) dorsal view, (GGGG) right lateral view, (HHHH) ventral view, and (IIII) proximal view. Pedal ungual AR-1-3182/31 in: (JJJJ) left lateral view, (KKKK) dorsal view, (LLLL) right lateral view, (MMMM) ventral view, and (NNNN) proximal view. Pedal ungual AR-1-3386/31 in: (OOOO) left lateral view, (PPPP) dorsal view, (QQQQ) ventral view, and (RRRR) proximal view. Pedal ungual AR-1-2986/31 in: (SSSS) left lateral view, (TTTT) dorsal view, (UUUU) right lateral view, (VVVV) ventral view, and (WWWW) proximal view. Manual ungual AR-1-3711/31 in: (XXXX) left lateral view, (YYYY) dorsal view, (ZZZZ) right lateral view, (AAAAA) ventral view, and (BBBBB) proximal view.

Fragment of ilium AR-1-3490/31 in: (A) lateral view and (B) ventral view. Fragment of ilium AR-1-3571/31 in (C) ventral view. Left ischium and fused pubis AR-1-3649/31 in: (D) lateral view, (E) proximal view, (F) anterior view, (G) distal view, (H) medial view, and (I) posterior view. Right ischium and fused pubis AR-1-3648/31 in: (J) lateral view, (K) anterior view, (L) medial view, and (M) posterior view. Red arrows indicate obturator foramen between fused ischium and pubis. Abbreviations: a = acetabulum, of = obturator foramen between fused ischium and pubis, p = pubis.

Mid-caudal vertebra AR-1-3717/31 in: (A) anterior view, (B) posterior view, (C) right lateral view, (D) dorsal view, and (E) ventral view. Mid-caudal vertebra AR-1-3348/31 in: (F) anterior view, (G) posterior view, (H) right lateral view, (I) dorsal view, and (J) ventral view. Medial posterior vertebra AR-1-3716/31 in: (K) posterior view and (L) right lateral view. Mid-caudal vertebra AR-1-3616/31 in: (M) anterior view and (N) right lateral view. Distal posterior vertebra with fused chevron AR-1-3615/31 in: (O) anterior view, (P) posterior view, (Q) right lateral view, (R) dorsal view, and (S) ventral view. Distal posterior vertebra AR-1-3478/31 in: (T) anterior view and (U) right lateral view. Distal posterior vertebra AR-1-3243/31 in: (V) anterior view and (W) right lateral view. Distal posterior vertebra with fused chevron AR-1-3206/31 in: (X) anterior view and (Y) right lateral view. Distal posterior vertebra AR-1-3265/31 in: (Z) posterior view and (AA) right lateral view. Distal posterior vertebra with fused chevron AR-1-2950/31 in: (BB) anterior view, (CC) posterior view, (DD) left lateral view, (EE) dorsal view, and (FF) ventral view. Fused pair of extreme distalmost caudal vertebrae with fused chevron AR-1-3714/31 in: (GG) right lateral view, (HH) dorsal view, and (II) ventral view. Terminal four fused posterior vertebrae with fused chevrons AR-1-3204/31 in: (JJ) right lateral view, (KK) dorsal view (KK), and (LL) ventral view.

Proximal posterior vertebra (2 or 3) AR-1-635/10 in: (A) anterior view, (B) posterior view, (C) right lateral view, (D) left lateral view, (E) dorsal view, and (F) ventral view. Proximal chevron AR-1-4451/10 in: (G) anterior view, (H) lateral view, and (I) posterior view. Proximal posterior vertebra (4 or 5) AR1-1-562/10 in: (J) anterior view, (K) posterior view, (L) right lateral view, (M) left lateral view, (N) dorsal view, and (O) ventral view. Proximal chevron AR-1-569/10 in: (P) anterior view, (Q) lateral view, and (R) posterior view. Proximal chevron AR-1-10/560 in: (S) anterior view, (T) lateral view, and (U) posterior view. Proximal posterior vertebra (5 or 6) AR-1-636/10 in: (V) anterior view, (W) posterior view, (X) right lateral view, (Y) left lateral view, (Z) dorsal view, and (AA) ventral view.

Caudosacral vertebra AR-1-3512/31 in: (A) posterior view, (B) right lateral view, (C) anterior view, (D) left lateral view, (K) dorsal view, and (P) ventral view. Sacrum AR-1-3446/31 in: (E) right lateral view, (J) left lateral view, (L) dorsal view, (O) anterior view, (Q) ventral view, and (V) posterior view. Medial section of synsacral rod (AR-1-3450/31) in: (F) left lateral view, (M) dorsal view, and (R) ventral view. Anteriormost centrum of synsacral rod (AR-1-3451/31) in: (G) right lateral view, (N) dorsal view, and (S) ventral view. Intermediate left sacral rib (AR-1-3460/31) in (H) posterior view and (T) posterior view. Anterior left sacral rib (AR-1-3452/31) in: (I) dorsal and (U) ventral view. Anterior end of synsacrum from AR-1/10; AR-1-154/10 in: (W) anterior view and (X) right lateral view. Initial reconstruction of the sacrum AR-1-3446, 3450, 3512/31 inverted for consistency in (Y) right lateral view.

Anterior dorsal vertebra with rib fragment AR-1-3662/31 in: (A) posterior view, (B) cranial view. Anterior dorsal vertebra AR-1-3672/31 in: (C) cranial view, (D) posterior view, (E) dorsal view, and (F) ventral view. Medial cervical vertebra AR-1-3633/31 in: (G) cranial view, (H) posterior view, (I) right lateral view, (J) left lateral view, (K) dorsal view, and (L) ventral view. Medial dorsal vertebra AR-1-3674/31 in: (M) cranial view, (N) posterior view, and (O) left lateral view. Medial dorsal vertebra AR-1-3489/31 in: (P) cranial view, (Q) posterior view, (R) right lateral view, (S) left lateral view, (T) dorsal view, and (U) ventral view. Medial dorsal vertebra AR-1-3675/31 in: (V) cranial view, (W) right lateral view, (X) left lateral view, (Y) dorsal view, and (Z) ventral view. Mid-dorsal vertebra AR-1-3704/31 in: (AA) cranial view, (BB) posterior view, (CC) left lateral view, (DD) ventral view, and (EE) dorsal view. Mid-dorsal vertebra AR-1-3673/31 in: (FF) cranial view, (GG) posterior view, (HH) right lateral view, (II) dorsal view, and (JJ) ventral view.

Anterior dorsal vertebra AR-1-638/10 in: (A) anterior view, (B) posterior view, (C) right lateral view, (D) left lateral view, (E) dorsal view, and (F) ventral view. Anterior dorsal vertebra with fused rib fragments AR-1-535/10 in: (G) dorsal view, (H) anterior view, (I) right lateral view, (J) posterior view, and (K) ventral view. Anterior dorsal vertebra with fused rib fragment AR-1-478/10 in: (L) posterior view, (M) right lateral view, (N) dorsal view, (O) left lateral view, (P) anterior view, and (Q) ventral view. Anterior dorsal vertebra with bases of fused ribs AR-1-448/10 in: (R) posterior view, (S) left lateral view, (T) right lateral view, (U) dorsal view, and (V) ventral view. Mid-dorsal vertebra AR-1-430/10 in: (W) anterior view, (X) posterior view, (Y) left lateral view, (Z) right lateral view, (AA) dorsal view, and (BB) ventral view. Mid/dorsal vertebra with bases of fused ribs AR-1-322/10 in: (CC) anterior view, (DD) posterior view, (EE) left lateral view, (FF) right lateral view, and (GG) ventral view. Mid-dorsal vertebra AR-1-566/10 in: (HH) posterior view, (II) anterior view, (JJ) left lateral view, and (KK) ventral view. Posterior dorsal vertebra AR-1-155/10 in: (LL) anterior view, (MM) posterior view, (NN) right lateral view, and (OO) ventral view.

Atlas AR-1-649/10 in: (A) anterior view, (B) posterior view, (C) right lateral view, (D) left lateral view, (E) dorsal view, and (F) ventral view. Mid-cervical rib AR-1-450/10 in: (G) anterior view and (H) posterior view. Anterior cervical vertebra AR-1-650/10 in: (I) anterior view, (J) posterior view, (K) right lateral view, (L) left lateral view, (M) dorsal view, and (N) ventral view. Anterior cervical vertebra AR-1-637/10 in: (O) anterior view, (P) posterior view, (Q) right lateral view, (R) left lateral view, (S) dorsal view, and (T) ventral view. Mid-cervical vertebra AR-1-449/10 in: (U) anterior view, (V) posterior view, (W) right lateral view, (X) dorsal view, and (Y) ventral view. Mid-cervical vertebra AR-1-431/10 in: (Z) anterior view, (AA) posterior view, (BB) left lateral view, (CC) right lateral view, (DD) dorsal view, and (EE) ventral view. Posterior cervical vertebra AR-1-533/10 in: (FF) anterior view, (GG) left lateral view, (HH) dorsal view, and (II) ventral view. Posterior right cervical rib AR-1-4452/10 in: (JJ) posterior view, (KK) anterior view, and (LL) ventral view. Abbreviation pvf = paired ventral fossae.

Maxillary teeth from holotype of Europelta carbonensis n. gen., n. sp., AR-1/10 (A-FF). Well-preserved tooth AR-1-324/10 in: (A) occlusal view, (B) distal view, (C) lateral view, (D) ligual view, and (E) anterior view. AR-1-482/10 in: (F) labial view and (G) ligual view. AR-1-325/10 in: (H) labial view and (I) ligual view. AR-1-563/10 in: (J) labial view and (K) ligual view. Possible premaxillary tooth AR-1-343/10 in: (L) labial view and (M) ligual view. AR-1-417/10 in: (N) labial view and (O) ligual view. AR-1-418/10 in: (P) labial view and (Q) ligual view. AR-1-358/10 in: (R) labial view and (S) ligual view. AR-1-423/10 in: (T) labial view and (U) ligual view. AR-1-564/10 in: (V) posterior view, (W) occlusal view, (X) labial view, (Y) ligual view, and (Z) mesial view. AR-1-428/10 in: (AA) labial view and (BB) ligual view. AR-1-323/10 in: (CC) labial view and (DD) ligual view. AR-1-567/10 in: (EE) labial view and (FF) ligual view. Dentary teeth from type of Europelta carbonensis n. gen., n. sp., AR-1/31 (GG-FFF). AR-1-3650/31 in: (GG) posterior view, (HH) occlusal view, (II) labial view, (JJ) ligual view, and (KK) mesial view. AR-1-3700/31 in: (LL) occlusal view, (MM) posterior view, (NN) labial view, (OO) ligual view, and (PP) mesial view. AR-1-3705/31 in: (QQ) labial view and (RR) ligual view. AR-1-3706/31 in: (SS) labial view and (TT) ligual view. AR-1-3524/31 in: (UU) labial view and (VV) ligual view. AR-1-3699/31 in: (WW) labial view and (XX) ligual view. AR-1-3432/31 in: (YY) labial view and (ZZ) ligual view. AR-1-3495/31 in: (AAA) labial view and (BBB) ligual view. AR-1-3701/31 in: (CCC) labial view and (DDD) ligual view. AR-1-3961/31 in: (EEE) labial view and (FFF) ligual view.

Nodosaurid ankylosaurs that share a combination of characters including: narrow predentaries; a nearly horizontal, unfused quadrates that are oriented less than 30° from the skull roof, and condyles that are 3 times transversely wider than long; premaxillary teeth and dentary teeth that are near the predentary symphysis; dorsally arched sacra; an acromion process dorsal to midpoint of the scapula-coracoid suture; straight ischia, with a straight dorsal margin; relatively long slender limbs; a sacral shield of armor; and erect sacral armor with flat bases. Struthiosaurinae is defined as the most inclusive clade containing Europelta but not Cedarpelta , Peloroplites, Sauropelta or Edmontonia .

Description and Comparisons

Mandible A small dentary fragment extending for only four complete alveolae (AR-1-133/10) was preserved from the holotype skeleton (Fig. 8 E–G). However, a robust left dentary and splenial are preserved together (AR-1-3698/31) from the paratype specimen (Fig. 10 A–E). The splenial is not in its posteriomedial position relative to the dentary, but is fused across the posterior portion of the tooth row transversely. Additionally, an isolated left angular with a distinct highly sculptured scale along its ventral margin (AR-1-2945/31), was recovered (Fig. 10 F, G). The dentary is 184.7 mm long with a minimum of 21 tooth positions, with no possibility of more than two unpreserved alveoli as determined by the position of the suture with the angular and surangular. As with the maxillary teeth, the alveoli are more than twice as large posteriorly. There is only 1.5 cm between the anteriormost alveoli and the symphysis, suggesting that there may have been premaxillary teeth as at least nine anterior teeth would have been positioned to oppose the premaxilla. The primitive ankylosaurs Sarcolestes [34], [98], Gargoyleosaurus, [85], Silvisaurus [76], Animantarx [97], Sauropelta [99], Anoplosaurus [17], Hungarosaurus [33] and Struthiosaurus [22] have a short anterior diastema, and thus a narrow predentary, whereas this diastema is longer in ankylosaurs with wide predentaries. However, the symphysis in Europelta is robust and dorsoventrally deeper (45.0 mm deep and 29.00 mm across) than in ankylosaurs [82], and is most similar to the deep symphysis of Hungarosaurus [32], further suggesting a reduced predentary with a rudimentary ventral process. The symphysis is marked by two deep anteroposteriorly directed grooves. A row of foramina extends posteriorly on the lateral surface of the dentary from just dorsal to the buccal recess to the notch for the surangular, whereas nutritive foraminae are not clearly visible ventral to the alveolae on the medial side of the dentary as in other ankylosaurs. The recessed tooth row is deflected medially and forms a convex arch in lateral view. The dentary of Hungarosaurus is deeper dorsoventrally than that of Europelta [33]. The splenial (Fig. 10 A-D) is a thin bone with a convex ventral margin 156.6 mm long that contacts the angular. It has the appearance of an obtuse triangle in medial view. There is large, well-developed intermandibular foramen (7 mm long and 5.3 mm wide) 50 mm from its anterior end. The angular (Fig. 10 F, G) has a maximum length of 175 mm. The lateral margin is highly rugose, because the bone is textured and remodeled to support a large scale, extending about 10–12 mm ventral to the ventral margin of the angular for most of its length. A distinct ridge marks the dorsal limit of the mandibular ornament medially, where it is in contact with the ventral margin of the splenial. Dorsal to this contact the bone is smooth. The ventral extent of the textured bone supporting the mandibular scale is similar to that observed in ankylosaurids such as Euoplocephalus [95] and Minataurasaurus [100], rather than the more lateral orientation found in Gargoyleosaurus [93] and in nodosaurids like Sauropelta [99] and Panoplosaurus [101].

Pectoral Girdle Parts of the right scapulocoracoid are preserved. A portion of the distal scapular blade (AR-1-429/10) is preserved with a portion of the distal ventral margin missing with a curved section broken away. There is no evidence of any distal expansion of the scapular blade as in many nodosaurids [94]. The coracoid (AR-1-657/10) is preserved with only the most proximal portion of the scapula fused on (Fig. 20 D–H). It appears to have been sheared off just dorsal to the suture between the coracoid and the scapula, perhaps in the process of removing the overlying coal seam. The coracoid is relatively equidimensional (201.3 mm long by 186.5 mm tall) relative to the elongate coracoids characteristic of many other nodosaurids [114] such as Peleroplites [86], Texasites [77], [115], and Animantarx [97]. The medial surface is concave and the lateral surface is convex giving it a bowl-shaped appearance. The ventral margin is evenly convex as in many polacanthids and nodosaurids and there is no anteroventral process as in all ankylosaurids, including Shamosaurus [91], [94]. The articular surface of the ventrally directed glenoid is wide, bounded by a flange that extends beyond the medial surface of the coracoid. Both xiphisternal plates are preserved (Figure 20I–L). The best preserved xiphisternal is approximately 350 mm long. They appear to be arcuate flat bones. Xiphisternal plates are only known in a few nodosaurids, but those of Europelta, whereas similar in overall shape to other nodosaurid xiphisterna, are not fenestrate or scalloped along their margins as in North American nodosaurids for which they are known [82], [87], [116].

Forelimb Parts of both humeri are preserved. The right humerus (AR-1-655/10) is represented by the proximal end (Fig. 21 A–D). It is 249.2 mm wide with a well-developed proximal head 91.9 mm wide that extends onto the posterior side of the humerus. Distinct notches separate both the laterally directed deltopectoral crest as in nodosaurids such as Sauropelta [70], [71], [99] and the internal tuberosity from the humeral head. The deltopectoral crest extends lateraly from the humerus and is not flexed anteriorly as in polacanthids and ankylosaurids [94]. The left humerus (AR-1-327/10) is represented by a midshaft for which both the proximal and distal ends appear to have rotted off and the core of the shaft has rotted away (Fig. 21 E–H). The shaft is deeply waisted relative to the proximal and distal ends. Although relatively uninformative, enough of this humerus is preserved to indicate that the deltopectoral crest would have made up less than 50% of the length of the humerus as in nodosaurids [71], [117] and in the basal ankylosaur Mymoorapelta (Kirkland, pers. obs.) compared to the longer deltopectoral crests of ankylosaurids [70], [71]. Overall, the humerus of Europelta is similar in proportions to Niobrarasaurus [118], [119]. The wide proximal end of the humerus figured by Ősi and Prondvai [120] as cf. Struthiosaurus is similar to that of Europelta, whereas the humerus of co-occuring Hungarosaurusis is more slender proportionally. Among the nine unguals preserved for AR-1/31, one specimen (AR-1-3711/31) may represent a manual ungual. It is more equidimensuional than the other eight more elongate unguals.