Additional skulls of Talarurus plicatospineus (Dinosauria: Ankylosauridae) and implications for paleobiogeography and paleoecology of armored dinosaurs

Journal Pre-proof Additional skulls of Talarurus plicatospineus (Dinosauria: Ankylosauridae) and implications for paleobiogeography and paleoecology of armored dinosaurs Jin-Young Park, Yuong-Nam Lee, Philip J. Currie, Yoshitsugu Kobayashi, Eva Koppelhus, Rinchen Barsbold, Octávio Mateus, Sungjin Lee, Su-Hwan Kim PII:

S0195-6671(19)30342-8

DOI:

https://doi.org/10.1016/j.cretres.2019.104340

Reference:

YCRES 104340

To appear in:

Cretaceous Research

Received Date: 9 August 2019 Revised Date:

26 October 2019

Accepted Date: 27 November 2019

Please cite this article as: Park, J.-Y., Lee, Y.-N., Currie, P.J., Kobayashi, Y., Koppelhus, E., Barsbold, R., Mateus, O., Lee, S., Kim, S.-H., Additional skulls of Talarurus plicatospineus (Dinosauria: Ankylosauridae) and implications for paleobiogeography and paleoecology of armored dinosaurs, Cretaceous Research, https://doi.org/10.1016/j.cretres.2019.104340. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Ltd.

1

Additional skulls of Talarurus plicatospineus (Dinosauria: Ankylosauridae) and

2

implications for paleobiogeography and paleoecology of armored dinosaurs

3 4

Jin-Young Park1, Yuong-Nam Lee1,*, Philip J. Currie2, Yoshitsugu Kobayashi3, Eva

5

Koppelhus2, Rinchen Barsbold4, Octávio Mateus5, Sungjin Lee1 and Su-Hwan Kim1

6 1

7

School of Earth and Environmental Sciences, Seoul National University, Seoul, 08826,

8

South Korea 2

9

Department of Biological Sciences, CW 405 Biological Sciences Building, University of

10

Alberta, Edmonton, AB T6G 2E9, Canada 3

11

Hokkaido University Museum, Kita 10, Nishi 8, Kita-Ku, Sapporo, Hokkaido, 060-0801,

12

Japan 4

13

Institute of Paleontology and Geology, Mongolian Academy of Sciences, Box-46/650,

14

Ulaanbaatar 15160, Mongolia 5

15

FCT-Universidade NOVA de Lisboa, Caparica 2829-516, Portugal

16 17

*

Corresponding author.

18 19

E-mail: [email protected] (Y.-N. Lee), [email protected] (J.-Y. Park),

20

[email protected] (P.J. Currie), [email protected] (Y. Kobayashi),

21

[email protected] (E. Koppelhus), [email protected] (O. Mateus), [email protected] (R.

22

Barsbold), [email protected] (S. Lee), [email protected] (S.-H. Kim) 1

23 24

Highlights

25

Three new specimens of Talarurus provide new anatomical information about this taxon.

26

A dispersal event of ankylosaurines from Asia to western North America occurred before

27 28

29

the Cenomanian. Differences of muzzle shape between Talarurus and Tsagantegia suggest a possible niche partitioning among these taxa.

30 31 32

Abstract Three new additional skull specimens of Talarurus plicatospineus have been

33

recovered from the Upper Cretaceous (Cenomanian–Santonian) Bayanshiree Formation, of

34

Bayan Shiree cliffs, eastern Gobi Desert, Mongolia. The skulls feature unique characters such

35

as an anteriorly protruded single internarial caputegulum, around 20 flat or concave nasal-

36

area caputegulae surrounded by a wide sulcus, a vertically oriented elongate loreal

37

caputegulum with a pitted surface, an elongate lacrimal caputegulum positioned above the

38

posterodorsal border of the maxilla, two longitudinally arranged large frontoparietal

39

caputegulae surrounded by smaller rhomboid caputegulae, small but elongate medial

40

supraorbital caputegulae, a posterior supraorbital caputegulum that is four times larger than

41

the anterior one, up to three transverse parallel grooves on the dorsal surface of the posterior

42

supraorbital caputegulum, postocular caputegulae along the ventral to posterior rim of the

43

orbit that extend almost to the anteroventral margin of the squamosal horn, a longitudinal

44

furrow tapering towards the apex of the squamosal horn, a lateral nuchal caputegulum four to 2

45

five times larger than other nuchal caputegulae, and a pterygovomerine keel with a ventral

46

margin that is dorsally positioned to the alveolar ridge. The phylogenetic analysis result

47

showed that Talarurus is sister to the clade that includes the derived Asian ankylosaurines

48

(Saichania chulsanensis, Tarchia kielanae, and Zaraapelta nomadis). It also shows that there

49

was dispersal of ankylosaurines from Asia into western North America before the

50

Cenomanian. Moreover, the rostral differences between Talarurus and Tsagantegia, another

51

ankylosaur from the same formation, suggest possible niche partitioning between these taxa.

52 53

Keywords: Dinosauria, Ankylosauridae, Ankylosauinae, Talarurus plicatospineus,

54

Bayanshiree Formation, paleobiogeography

55 56 57

1. Introduction Talarurus plicatospineus (Maleev, 1952) is an armored dinosaur from the Upper

58

Cretaceous Bayanshiree Formation of Mongolia. Since its initial discovery, numerous

59

specimens have been collected, including partial postcranial skeletons of six individuals from

60

the Bayan Shiree cliffs and many fragmentary specimens from nearby localities (Tumanova,

61

1987, 2000; Arbour and Currie, 2016). However, cranial elements of Talarurus are rare, and

62

only two incomplete skulls including the holotype have been described in the scientific

63

literature (Maleev, 1952; Tumanova, 1987). The holotype skull (PIN 557-91) only includes

64

the frontal, parietal, and occipital regions with partial squamosal horns (Maleev, 1952).

65

Another partial cranium (PIN 3780/1) includes the skull roof, occipital regions, and a nearly

66

complete braincase (Tumanova, 1987). Both specimens lack the premaxillae and maxillae,

67

ventral rami of the jugals, the ventral postorbital regions (including the quadratojugal horns),

68

most of the palatal elements, and the mandibles. Therefore, much of the cranial morphology 3

69 70

of Talarurus has been unknown. Here we present three new additional skulls of Talarurus, which are much more

71

complete than the previously reported materials. They allow us to more accurately reconstruct

72

the overall shape of the skull of Talarurus, and to understand detailed cranial anatomy of this

73

taxon. Furthermore, they provide new information on ankylosaur phylogeny, intercontinental

74

exchange of ankylosaurines between Asia and North America during the Cretaceous, and also

75

have implications for understanding niche partitioning among armored dinosaurs.

76 77

1.1. Institutional abbreviations

78

MPC, Mongolian Paleontological and Geological Institute, Mongolian Academy of Sciences,

79

Ulaanbaatar, Mongolia; PIN, Paleontological Institute, Russian Academy of Sciences,

80

Moscow, Russia.

81 82 83

2. Geological setting The Bayanshiree Formation is a terrestrial sedimentary succession and is up to 300 m

84

thick (Martinson, 1982; Jerzykiewicz and Russell, 1991; Hicks et al., 1999; Jerzykiewicz,

85

2000). The formation conformably overlies the Sainshand Formation and underlies the

86

Javkhlant Formation (Eberth et al., 2009). It is widely distributed in the eastern Gobi basins

87

of Mongolia (Jerzykiewicz and Russell, 1991; Hicks et al., 1999), comprising multi-colored

88

clays with fluvial fine-grained sandstones with calcareous concretions (Vasiliev et al., 1959),

89

and conglomerates (Sochava, 1975; Martinson, 1982; Jerzykiewicz, 2000). A variety of

90

fossils have been discovered from the Bayanshiree Formation, including freshwater ostracods

91

and mollusks (Barsbold, 1972; Sochava, 1975; Hicks et al., 1999), fishes (Efremov, 1949), an 4

92

abundance of turtles (Mlynarski and Narmandach, 1972; Sukhanov and Narmandach, 1975;

93

Chkhikvadze and Shuvalov, 1980; Jerzykiewicz and Russell, 1991; Sukhanov, 2000; Danilov

94

et al., 2014), neosuchian crocodyliforms (Efimov, 1983; Jerzykiewicz and Russell, 1991;

95

Turner, 2015; Lee et al., 2019), and a wide range of dinosaurs such as ankylosaurs (Maleev,

96

1952; Tumanova, 1987, 1993; Arbour and Currie, 2016), ceratopsians (Maryañska and

97

Osmolska, 1975; Jerzykiewicz and Russell, 1991), hadrosauroids (Maryañska and Osmolska,

98

1975, 1981; Tsogtbaatar et al., 2019), sauropods (Martinson, 1982), tyrannosaurids (Perle,

99

1977), ornithomimosaurs (Jerzykiewicz and Russell, 1991; Makovicky et al., 2004),

100

therizinosaurids (Jerzykiewicz and Russell, 1991; Russell and Dong, 1993), and

101

dromaeosaurids (Barsbold, 1983). Comparisons to vertebrate faunas of North American non-

102

marine units, which are well confined by ammonite zonation and palynology, yield a late

103

Cenomanian Coniacian to early Santonian age (Jerzykiewicz and Russell, 1991). However,

104

magnetostratigraphical and palynological analysis suggests a deposit age between

105

Cenomanian to no later than the Santonian (Hicks et al., 1999).

106 107 108

3. Materials and methods All new Talarurus specimens (MPC-D 100/1354, MPC-D 100/1355, and MPC-D

109

100/1356) were collected from the sandstone layer at the type section of the Bayanshiree

110

Formation, eastern Gobi Desert, Mongolia during the Korea-Mongolia International Dinosaur

111

Expedition in 2007 (Fig. 1). Fossil preparation was done at the Hwaseong City laboratory of

112

South Korea in 2013, and the specimens are now permanently held in the Institute of

113

Paleontology and Geology in Ulaanbaatar, Mongolia. All measurements were taken using a

114

measuring tape and a digital caliper. Comparisons to other ankylosaurid taxa were made by 5

115

examining some specimens in MPC and from published literature. The term ‘caputegulum’

116

(sensu Blows, 2001) is used herein to refer to cranial ornamentation.

117

To determine the phylogenetic position, the skull-related characters of Talarurus

118

were re-coded into the data matrix of Zheng et al. (2018), with addition of Akainacephalus

119

(Wiersma and Irmis, 2018). “Zhejiangosaurus” and all nodosaurids, with the exception of

120

Gargoyleosaurus and Nodosaurus, were excluded for improved consistency index. We have

121

also corrected one error in the data matrix of Tsagantegia (character state 15:1 was changed

122

to 15:0). We should note that the data matrix of Zheng et al. (2018), which is based on Arbour

123

and Currie (2016), includes Minotaurasaurus ramachandrani within Tarchia kielanae,

124

Tarchia teresae within Saichania chulsanensis, and Oohkotokia horneri within Scolosaurus

125

cutleri. The revised dataset of 177 characters and 27 taxa (25 ingroup and two outgroup taxa)

126

were analyzed using TNT (Tree Analysis Using New Technology) version 1.1 (Goloboff et al.,

127

2008). All characters were treated as unordered and of equal weight. A traditional search

128

(Wagner trees; swapping algorithm: tree bisection-reconnection; random seeds: 1; replicates:

129

1000; trees to save per replication: 10) was performed, and the ‘Bremer.run’ script was used

130

to calculate the Bremer support values on each node of the strict consensus tree.

131 132

4. Systematic paleontology

133

Dinosauria Owen, 1842

134

Ornithischia Seeley, 1887

135

Thyreophora Nopcsa, 1915 (sensu Norman, 1984)

136

Ankylosauria Osborn, 1923 6

137

Ankylosauridae Brown, 1908

138

Ankylosaurinae Nopcsa, 1918 (sensu Sereno, 1998)

139

Talarurus plicatospineus Maleev, 1952

140

Type specimen. PIN 557, an incomplete posterior portion of skull (Maryañska, 1977).

141

Postcranial materials from at least three different individuals were originally included by

142

Maleev (1956) as part of the holotype, but were subsequently excluded by Maryañska (1977).

143

Studied specimens. MPC-D 100/1354 (Figs. 2 8), a nearly complete cranium except for the

144

damaged right dorsal surface. MPC-D 100/1355 (Figs. 2 7 and 9), a skull (lacking the nasal

145

area) plus one partial left mandible, and one partial cervical half ring, one dorsal vertebra, one

146

dorsal rib piece and other postcranial fragments. MPC-D 100/1356 (Figs. 2 7), a cranium

147

lacking the nasal area.

148

Locality and horizon. Holotype and all other materials are from the Upper Cretaceous

149

(Cenomanian Santonian) Bayanshiree Formation, Bayan Shiree cliffs, eastern Gobi Desert,

150

Mongolia.

151

Revised diagnosis. An ankylosaurid distinguished by the following unique set of characters

152

(autapomorphies with an asterisk): an anteriorly protruded single internarial caputegulum*;

153

around 20 flat or concave caputegulae surrounded by a wide sulcus present in the nasal

154

region*; a vertically oriented, elongate loreal caputegulum with pitted surface*; an elongate

155

lacrimal caputegulum positioned above the posterodorsal border of the maxilla*; two

156

longitudinally arranged large frontoparietal caputegulae surrounded by smaller rhomboid 7

157

caputegulae*; small but elongate medial supraorbital caputegulae*; a posterior supraorbital

158

caputegulum that is four times larger than the anterior one*; up to three transverse parallel

159

grooves on the dorsal surface of the posterior supraorbital caputegulum*; a “neck” present at

160

the base of the quadratojugal horn (shared with Pinacosaurus mephistocephalus and

161

Minotaurasaurus); postocular caputegulae ventral to the posterior rim of the orbit extend

162

almost to the anteroventral margin of the squamosal horn*; a longitudinal furrow tapering

163

towards the apex of the squamosal horn*; a lateral nuchal caputegulum four to five times

164

larger than surrounding nuchal caputegulae*; ventral margin of the pterygovomerine keel

165

positioned dorsal to the alveolar ridge*; paired basal tubera of basisphenoid medially divided

166

(shared with Akainacephalus and Gobisaurus); short paroccipital span that does not reach the

167

squamosal horns (shared with Akainacephalus and Minotaurasaurus).

168

Remarks. All skull materials of Talarurus (PIN 557, 3780/1 and MPC-D 100/1354, 100/1355,

169

100/1356) share the following characters: polygonal nasal and frontal caputegulae with wide

170

sulci between each; no lacrimal incisure (sensu Arbour et al., 2014b); large frontoparietal

171

caputegulae surrounded by smaller caputegulae; small but elongate medial supraorbital

172

caputegulae; laterally protruding large posterior supraorbital caputegulae; no overlap between

173

the posterior border of the supraorbital caputegulum and the anterior border of squamosal

174

horn in lateral view; transverse frontoparietal depression (sensu Godefroit et al., 1999); large

175

lateral nuchal caputegulum that is four to five times larger than the medial ones; nuchal

176

caputegulae slightly overhang the posterior margin of the skull; nuchal shelf ventrally fused

177

with the supraoccipital and the paroccipial processes; anterolaterally projected short and stout

178

basipterygoid processes; medially divided and rounded rugose basal tubera on basisphenoid;

179

posteroventrally directed reniform occipital condyle; foramen magnum wider than high; 8

180

sagittal nuchal ridge on supraoccipital that increases in transverse width ventrally and

181

dorsally; short paroccipital span that does not reach the squamosal horns; paroccipital process

182

tapers in height towards the lateral terminus and curves ventrally. Among these features, the

183

overall morphology of the caputegulae in general and the supraorbital and nuchal caputegulae

184

in particular are considered to be diagnostic. Therefore, it is apparent that all three new

185

specimens are Talarurus.

186

Talarurus was previously diagnosed by Arbour and Currie (2016) based on a single

187

autapomorphy, which is the presence of a unique V-shaped upraised area, anteromedial to the

188

transverse frontoparietal depression. This V-shaped area is observable in PIN 557-91.

189

Although Penkalski (2018) considered this as a possible result of taphonomic alteration, it is

190

obvious that it is the anterior boundary of the posteriorly situated large frontoparietal

191

caputegulum. However, this boundary is transversely linear in PIN 3780/1 and MPC-D

192

100/1355. It also appears to be W-shaped in MPC-D 100/1356 (Fig. 4). We consider this to be

193

intraspecific variation.

194

Description. All of three skulls are similar in size (Table. 1). MPC-D 100/1354 is 301 mm in

195

length and 372 mm in greatest width across the two quadratojugal horns. The preserved

196

portion of MPC-D 100/1355 is 262 mm in length and 333 mm in greatest width. The

197

preserved mandibular element of MPC-D 100/1355 is 137 mm in length and 75 mm in

198

greatest height. The preserved portion of MPC-D 100/1356 is 249 mm in length and 265 mm

199

in greatest width. In dorsal view, all skulls are trapezoidal in shape and wider than long (Fig.

200

4). Although MPC-D 100/1355 includes a few isolated postcranial elements, in this paper

201

only the skull materials of Talarurus are being considered and the postcranial elements of

202

MPC-D 100/1355 will be presented elsewhere. The neuroanatomy of MPC-D 100/1354 was 9

203

already fully described (Paulina-Carabajal et al., 2018). For more detailed comparative

204

description of MPC-D 100/1354, 100/1355, and 100/1356, see supplementary text 1.

205

Rostral region: The premaxillae (Figs. 2 6 and 8) are fused although an interpremaxillary

206

suture (sensu Vickaryous and Russell, 2003) is present. A premaxillary notch can be observed

207

on the anterior tip. The anterior boundary of the combined premaxillae is straight transversely

208

and the broad internarial bar is oriented vertically. The exposed premaxilla-maxilla suture

209

inclines posterodorsally. The palatal surfaces of the premaxillae are broad and rectangular.

210

There are no premaxillary teeth. The external nares are triangular and face anterolaterally. A

211

single paranasal aperture is present behind the internarial bar (Fig. 8). The external nares are

212

rimmed dorsally by the elongate supranarial caputegulae. A single large internarial

213

caputegulum protrudes anteriorly over the premaxillae (Figs. 2 4 and 8). Around 20

214

caputegulae are present in the nasal region (Fig. 4). These caputegulae are relatively small,

215

mostly irregular, flat or concave, and are surrounded by a wide sulcus. The exposed maxillae

216

are anteroposteriorly elongate and extend below the orbits. In palatal view (Fig. 5), the

217

convex maxillary tooth row is situated medial to the buccal emargination. At least 23 alveoli

218

are present in each maxilla, but no maxillary teeth are preserved. Two loreal caputegulae are

219

present on each side (Figs. 2 and 3). The most anterior loreal caputegulum is large and

220

rhomboid, whereas the posteriormost loreal caputegulum is elongate. Only one lacrimal

221

caputegulum is present on each sides (Figs. 2 and 3). This small, elongate ornament is located

222

above the posterodorsal border of the maxilla. A large rhomboid “prefrontal” caputegulum is

223

behind the loreal caputegulae, and an additional small prefrontal caputegulae is present along

224

the anteromedial border of the anterior supraorbital caputegulum (Fig. 4). 10

225

Temporal region: The frontoparietal caputegulae (Fig. 4) form a mosaic pattern. Two large

226

frontoparietal caputegulae are medially positioned on the skull roof. These ornamentations

227

are transversely wide, mostly hexagonal, and are surrounded by smaller caputegulae. In the

228

holotype, only the posteriormost large frontoparietal caputegulum is preserved, and it is

229

triangular. Three small medial supraorbital caputegulae (Fig. 4) are longitudinally arranged

230

along the medial border of the supraorbital caputegulae. The keeled supraorbital caputegulae

231

(Figs. 2 4) have distinct apices. The posterior supraorbital caputegulum is about four times

232

larger in area than the anterior one. Shallow transverse grooves can be observed on the dorsal

233

surface of the posterior supraorbital caputegulum. The orbits (Figs. 2, 3 and 6) face

234

anterolaterally and tilt somewhat ventrally. The orbital rim thickens posteriorly. The

235

triangular quadratojugal horns (Figs. 2, 3 and 5 7) project lateroventrally. Proximally and

236

anteriorly, each horn ends behind the orbit and does not contact the jugal, which results in a

237

quadratojugal “neck” (sensu Arbour and Currie, 2016). Up to seven postocular caputegulae

238

(sensu Arbour and Currie, 2016) (Figs. 2 and 3) are situated behind the orbit. A wide

239

transverse frontoparietal depression (Figs. 2, 3 and 4) is present posteromedial to the

240

posterior supraorbital caputegulae. The rounded, triangular squamosal horns (Figs. 2 4)

241

project posterolaterally, have dorsolateral keels, and have triangular bases. A longitudinal

242

furrow can be observed on the keel. Three caputegulae are present on each side of the

243

dorsally raised nuchal shelf (Fig. 4). The high-relief lateral nuchal caputegulum is four to five

244

times larger than the surrounding nuchal ornamentations. The nuchal shelf is fused with the

245

supraoccipital and the paroccipial processes in occipital view (Fig. 7).

246

Palatal region: The dorsoventrally thin rostral extension of the vomer (Fig. 5) is splayed and 11

247

fused over the posteromedial region of the premaxillae. The laterally thin osseous nasal

248

septum (sensu Vickaryous and Russell, 2003) meets the skull roof dorsally and sagittally

249

divides the rostrum. Posterolateral to the vomer is the pterygoid, but only a fragmentary right

250

element is preserved in MPC-D 100/1355 (Fig. 5). A small, wedge-shaped left ectopterygoid

251

is preserved in MPC-D 100/1354 (Fig. 5), which contributes to the anteromedial border of the

252

supratemporal fenestra.

253

Occipital/Basicranial region: The parasphenoid (Fig. 5) tapers anteriorly into a triangular

254

rostrum (sensu Vickaryous and Russell, 2003). The anteroposterior length of the basisphenoid

255

and basioccipital are similar. Short, stout basipterygoid processes are present on the

256

basisphenoid (Fig. 5). Posterior to these processes are medially divided, rounded basal tubera.

257

The ventral surface of the basioccipital (Fig. 5) is convex. Only the basioccipital contributes

258

the occipital condyle in MPC-D 100/1354 and 100/1355. However, the exoccipitals also form

259

part of the condyle in the holotype (Maleev, 1956). The reniform occipital condyle is oriented

260

posteroventrally. The ovoid foramen magnum is wider than high. A dorsoventral, sagittal

261

nuchal ridge (sensu Vickaryous et al., 2001) is present in between the foramen magnum and

262

nuchal shelf. This medial ridge divides the supraoccipital region into two shallow fossae. Two

263

small exoccipital protuberances project posteroventrally. The paraoccipital span does not

264

reach the squamosal horns (Fig. 5). The lateral terminus of the paroccipital process is not

265

fused to the squamosal condyle of the quadrates. Each quadrate (Figs. 5 and 6) is transversely

266

broad and the pterygoid flange extends from the quadrate body more ventrally than in other

267

ankylosaurids. In lateral aspect, the quadrate curves anteriorly but is obscured by the

268

quadratojugal horn (Figs. 2 and 3).

269

Mandibles: Only the partial right dentary is preserved in MPC-D 100/1355 (Fig. 9). This 12

270

represents the first mandibular element ever found for Talarurus. The ramus tapers anteriorly

271

and curves ventromedially. A predentary sulcus is present on the anterodorsal edge. No

272

alveoli are preserved. The rugose lateral surface has a few foramina on the posterodorsal

273

region. A shallow shelf is present along the dorsomedial portion of the mandibular ramus.

274

The Meckelian groove (sensu Vickaryous and Russell, 2003) can also be observed on the

275

medial surface.

276 277 278

5. Phylogenetic analysis The phylogenetic analysis resulted in 60 most parsimonious trees (tree length = 276

279

steps, consistency index = 0.547, and retention index = 0.56). The strict consensus tree shows

280

that Talarurus is sister to the clade that includes derived Asian taxa, such as Saichania

281

(including Tar. teresae), Tar. kielanae (including Minotaurasaurus) and Zaraapelta. The clade

282

that includes Talarurus, Saichania, Tar. kielanae, and Zaraapelta shares only one

283

synapomorphy: the presence of small postocular caputegulae posterolateral to the orbit

284

(character 50, state 1). Two North American taxa Akainacephalus and Nodocephalosaurus

285

appear to be basal to this clade.

286 287

6. Discussion

288

6.1. Phylogenetic placement of Talarurus plicatospineus

289

The phylogenetic placement of Talarurus has always been problematic. In Hill et al.

290

(2003), Talarurus was recovered as a sister taxon to the clade that includes derived

291

ankylosaurines such as Ankylosaurus, Euoplocephalus, Nodocephalosaurus, Saichania, 13

292

“Shanxia” (synonym of Saichania), “Tarchia gigantea” (now partially Tar. teresae), and

293

“Tianzhenosaurus” (synonym of Saichania). A similar result was also obtained in a more

294

recent analysis of Arbour and Evans (2017), which placed Talarurus outside of the clade that

295

includes the derived ankylosaurines, such as Ankylosaurus, Ano. lambei, Dyoplosaurus,

296

Euoplocephalus, Saichania, Sc. Cutleri, Tar. kielanae, Ziapelta, and Zuul. Vickaryous et al.

297

(2004) placed Talarurus within the derived clade of Asian ankylosaurines, which includes

298

Pinacosaurus, Saichania, and “Tianzhenosaurus”. The result of Thompson et al. (2012) is

299

similar to that of Vickaryous et al. (2004), and placed Talarurus within the clade that includes

300

Saichania, “Tar. gigantea” and “Tianzhenosaurus”. In more recent analyses (Arbour and

301

Currie, 2016; Zheng et al., 2018), however, Talarurus was positioned within the derived clade

302

of North American Ankylosaurini. Our results (Fig. 10) are somewhat similar to those of

303

Vickaryous et al. (2004) and Thompson et al. (2012).

304 305

6.2. Paleobiogeographic dispersal of ankylosaurines from Asia to North America

306

North American ankylosaurines are known from the middle to late Campanian to Late

307

Maastrichtian (Arbour and Currie, 2016; Penkalski and Tumanova, 2017; Penkalski, 2018;

308

Wiersma and Irmis, 2018). Because the temporal range of these taxa does not go below the

309

Santonian-Campanian boundary, earlier researchers speculated that the paleobiogeographic

310

dispersal of derived ankylosaurids between Asia and western North America must have

311

occurred during or earlier than the Campanian (Sullivan, 1999; Arbour et al., 2014a; Wiersma

312

and Irmis, 2018). However, the placement of two North American taxa, Akainacephalus and

313

Nodocephalosaurus, basal to Talarurus in our cladogram suggests that a migration occurred

314

before the Cenomanian (Fig. 11). We hypothesize that the paleobiogeographic dispersal of 14

315

ankylosaurines happened at least twice, one earlier than the Cenomanian and the other during

316

or before the Campanian. The migration of ankylosaurines from Asia to western North

317

America may be concordant with the records of other dinosaurs such as tyrannosauroids

318

(Loewen et al., 2013), therizinosaurids (Zanno, 2010), caenagnathids (Funston et al., 2018),

319

and hadrosauroids (Prieto-Márquez, 2010).

320 321

6.3. Paleoecology of armored dinosaurs in the Bayanshiree Formation

322

Only two ankylosaur taxa, Talarurus and Tsagantegia, are known from the

323

Bayanshiree Formation (Maleev, 1952; Tumanova, 1987, 1993). The skulls of the two taxa

324

are similar in size (up to 301 mm and 300 mm in length, respectively). Nevertheless, the

325

rostra of both taxa are quite different from each other in shape (Fig. 12). In lateral view, the

326

palatal surface of the premaxilla slopes down anteriorly in Talarurus, resulting in a ventrally

327

pointing rostral tip. In Tsagantegia, however, it is horizontal like the skull roof, and the

328

rostral tip protrudes anteroventrally. In palatal view, the palatal surface of the premaxilla of

329

Talarurus is broad and sub-rectangular, with a transversely straight anterior boundary. In

330

contrast, the snout of Tsagantegia is somewhat shovel-shaped, with a rounded anterior

331

boundary.

332

The rostral differences between these two taxa may be evidence of niche partitioning.

333

A similar case can be observed in modern mammals such as the white (Ceratotherium) and

334

black rhinoceros (Diceros). Both genera are distributed in central to southern Africa, and are

335

similar in size measuring up to 4 m in length and weighing up to 3,500 kg (Steele, 1960;

336

Nowak, 1991). The white rhinoceros has a broad rectangular muzzle, whereas the muzzle of

337

the black rhinoceros protrudes and is rounded (Groves, 1972; Hillman-Smith and Groves, 15

338

1994). The rostral differences provide a direct clue to the feeding habits of these two

339

rhinocerotid taxa. The white rhinoceros, being a grazer, consumes low-lying vegetation

340

(Groves, 1972). In contrast, the black rhinoceros, being a browser, prefers high-growing

341

shrubs (Hillman-Smith and Groves, 1994). The white rhinoceros might be the modern

342

equivalent of Talarurus, with the black rhinoceros analogous to Tsagantegia. Like the white

343

rhinoceros, the wide muzzle of Talarurus would have enhanced cropping vegetation along a

344

flat surface. Similar niche-related rostral morphologies are also known in ungulates and

345

ground sloths (Janis and Ehrhardt, 1988; Solounias and Moelleken, 1993; Solounias et al.,

346

1988; Susana Bargo et al., 2006).

347 348 349

7. Conclusions The three new specimens provide detailed and nearly complete anatomical

350

information on the skull of Talarurus (Fig. 13). Our cladistic analysis suggests that Talarurus

351

is sister to the clade that includes Saichania chulsanensis (including Tarchia teresae), Tarchia

352

kielanae (including Minotaurasaurus) and Zaraapelta nomadis. A dispersal event of

353

ankylosaurines from Asia to western North America occurred before the Cenomanian. The

354

rostral morphology of Talarurus is different from that of Tsagantegia, another ankylosaurine

355

from the Bayanshiree Formation, suggesting possible niche partitioning among these taxa.

356

The former was probably a grazer whereas the latter was a browser.

357 358

Acknowledgements

359

Thanks go to all members of KID Expedition in 2007. We also thank J.P. Wiersma

360

(Department of Geosciences, James Cook University) for sharing the data matrix of 16

361

Akainacephalus. P. Penkalski (Laboratories of Anatomy, University of Pennsylvania) and one

362

anonymous reviewer helped improve this manuscript, and we are grateful for their comments.

363

This research is supported by the National Research Foundation of Korea (grant number

364

2019R1A2B5B02070240) to Y.-N. Lee.

365 366

References

367

Arbour, V.M., Currie, P.J., 2016. Systematics, phylogeny and palaeobiogeography of the

368

ankylosaurid dinosaurs. Journal of Systematic Palaeontology 14, 385 444.

369

Arbour, V.M., Evans, D.C., 2017. A new ankylosaurine dinosaur from the Judith River

370

Formation of Montana, USA, based on an exceptional skeleton with soft tissue

371

preservation. Royal Society Open Science 4, 161086.

372

http://doi.org/10.1098/rsos.161086.

373

Arbour, V.M., Burns, M.E., Sullivan, R.M., Lucas, S.G., Cantrell, A.K., Fry, J., Suazo, T.L.,

374

2014a. A New Ankylosaurid Dinosaur from the Upper Cretaceous (Kirtlandian) of

375

New Mexico with Implications for Ankylosaurid Diversity in the Upper Cretaceous of

376

Western North America. PLoS ONE 9, e108804.

377

http://doi.org/10.1371/journal.pone.0108804.

378

Arbour, V.M., Currie, P.J., Badamgarav, D., 2014b. The ankylosaurid dinosaurs of the Upper

379

Cretaceous Baruungoyot and Nemegt formations of Mongolia. Zoological Journal of

380

the Linnean Society 172, 631 652.

381

Barsbold, R., 1972. Biostratigrafia I presnevodnye molluski verkhego mela gobiyskoy chasti

382

MNR [Biostratigraphy and Freshwater Molluscs of the Upper Cretaceous of the Gobi

383

part of the Peoples’ Republic of Mongolia]. Moscow, Nauka. 88 pp. [In Russian] 17

384

Barsbold, R. 1983. Khishchnye dinozavry mela Mongolii [Carnivorous dinosaurs from the

385

Cretaceous of Mongolia]. Trudy Sovmestnaya Sovetsko–Mongol’skaya

386

Paleontologicheskaya Ekspeditsia [Transactions of Joint Soviet-Mongolian Scientific

387

Research and Geological Expedition] 19, 1 120. [In Russian]

388 389

390

Blows, W.T., 2001. Dermal armor of the polacanthine dinosaurs. In: Carpenter, K. (Ed.), The Armored Dinosaurs. Indiana University Press, Bloomington, Indiana, 363 385. Brown, B., 1908. The Ankylosauridae, a new family of armored dinosaurs from the Upper

391

Cretaceous. Bulletin of the American Museum of Natural History 24, 187 201.

392

Chkhikvadze, V.M., Shuvalov, V.F., 1980. K voprosu o proiskhozhdenii trekhogotnykh

393

cherepakh [The problem of the origin of the three-clawed turtles]. Soobshcheniya

394

Akudemii Nauk Gruzinskoy SSR [Reports of the Akademia of Sciences of the

395

Georgian SSR] 100, 501 503. [In Russian]

396

Danilov, I.G., Hirayama, R., Sukhanov, V.B., Suzuki, S., Watabe, M., Vitek, N.S., 2014.

397

Cretaceous soft-shelled turtles (Trionychidae) of Mongolia: new diversity, records and

398

a revision. Journal of Systematic Palaeontology 12, 799 832.

399

Eberth, D.A., Kobayashi, Y., Lee, Y.-N., Mateus, O., Therrien, F., Zelenitsky, D.K., Norell,

400

M.A., 2009. Assignment of Yamaceratops dorngobiensis and associated redbeds at

401

Shine Us Khudag (eastern Gobi, Dorngobi Province, Mongolia) to the redescribed

402

Javkhlant Formation (Upper Cretaceous). Journal of Vertebrate Paleontology 29, 295

403

302.

404

Efimov, M.B., 1983. Obzor iskopaemykh krokodilov Mongolii [Revision of the fossil 18

405

crocodiles of Mongolia]. Trudy Sovmestnaya Sovetsko–Mongol’skaya

406

Paleontologicheskaya Ekspeditsia [Transactions of Joint Soviet-Mongolian Scientific

407

Research and Geological Expedition] 24, 76 95. [In Russian]

408

Efremov, I.A. 1949. Predvaritelnye rezultaty rabot I Mongolskoy Paleontologicheskoy

409

Ekspeditsii AN SSSR 1946 goda [Preliminary results of the work of the first

410

Mongolian Paleontological Expedition of the Academy of Sciences USSR, 19461].

411

Trudy Mongolskoy Komissii AN SSSR [Proceedings of the Mongolian Commission

412

of the Academy of Sciences of the USSR] 38, 8 27. [In Russian]

413

Funston, G.F., Mendonca, S.E., Currie, P.J., Barsbold, R., 2018. Oviraptorosaur anatomy,

414

diversity and ecology in the Nemegt Basin. Palaeogeography, Palaeoclimatology,

415

Palaeoecology 494, 101 120.

416

Godefroit, P., Pereda-Suberbiola, X., Li, H., Dong, Z.-M., 1999. A new species of the

417

ankylosaurid dinosaur Pinacosaurus from the Late Cretaceous of Inner Mongolia (P.

418

R. China). Bulletin de l’Institut Royal des Sciences Naturelles de Belgique 69 (Suppl.

419

B), 17 36.

420 421

Goloboff, P.A., Farris, J.S., Nixon, K.C., 2008. TNT, a free program for phylogenetic analysis. Cladistics 24, 774 786.

422

Groves, C.P., 1972. Ceratotherium simum. Mammalian Species 8, 1 6.

423

Hicks, J.F., Brinkman, D.L., Nichols, D.J., Watabe, M., 1999. Paleomagnetic and palynologic

424

analyses of Albian to Santonian strata at Bayn Shireh, Burkhant, and Khuren Dukh,

19

425

426

eastern Gobi Desert, Mongolia. Cretaceous Research 20, 829 850. Hill, R.V., Witmer, L.M., Norell, M.A., 2003. A New Specimen of Pinacosaurus grangeri

427

(Dinosauria: Ornithischia) from the Late Cretaceous of Mongolia: Ontogeny and

428

Phylogeny of Ankylosaurs. American Museum Novitates 3395, 1 29.

429

Hillman-Smith A.K., Groves, C.P., 1994. Diceros bicornis. Mammalian Species 455, 1 8.

430

Janis, C. M., Ehrhardt, D., 1988. Correlation of relative muzzle width and relative incisor

431

width with dietary preference in ungulates. Zoological Journal of the Linnean Society

432

92, 267 284.

433

Jerzykiewicz, T., 2000. Lithostratigraphy and sedimentary settings of the Cretaceous dinosaur

434

beds of Mongolia. In: Benton, M.J., Shishkin, M.A., Unwin, D.M., Kurochkin, E.N.

435

(Ed.), The Age of Dinosaurs in Russia and Mongolia. Cambridge University Press,

436

Cambridge, 279 296.

437 438

Jerzykiewicz, T., Russell, D.A., 1991. Late Mesozoic stratigraphy and vertebrates of the Gobi Basin. Cretaceous Research 12, 345 377.

439

Lee, Y.-N., Lee, H.-J., Kobayashi, Y., Paulina-Carabajal, A., Barsbold, R., Fiorillo, A.R.,

440

Tsogtbaatar, K., 2019. Unusual locomotion behaviour preserved within a

441

crocodyliform trackway from the Upper Cretaceous Bayanshiree Formation of

442

Mongolia and its palaeobiological implications. Palaeogeography, Palaeoclimatology,

443

Palaeoecology 533, 109239. http://doi.org/10.1016/j.palaeo.2019.109239.

444 445

Loewen, M.A., Irmis, R.B., Sertich, J.J.W., Currie, P.J., Sampson, S.D., 2013. Tyrannt Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans. PLoS ONE 8, 20

446

e79420. http://doi.org/10.1371/journal.pone.0079420.

447

Lü, J., Jin, X., Sheng, Y., Li, Y., Wang, G., Azuma, Y., 2007. New nodosaurid dinosaur from

448

the Late Cretaceous of Lishui, Zhejiang Province, China. Acta Geologica Sinica 81,

449

344 350.

450

Makovicky, P.J., Kobayashi, Y., Currie, P.J., 2004. Ornithomimosauria. In: Weishampel, D.B.,

451

Dodson, P., Osmólska, H. (Ed.), The Dinosauria, second edition. University of

452

California Press, Berkeley and Los Angeles, California, 137 150.

453

Maleev, E.A., 1952. Noviy ankilosavr is verchnego mela Mongolii [New ankylosaur of the

454

Upper Cretaceous of Mongolia]. Doklady Akademii Nauk SSSR 87, 273 276. [In

455

Russian]

456

Maleev, E.A., 1956. Pantsyrnye dinosavry verchnego mela Mongolii (Semeustvo

457

Ankylosauridae) [Armored dinosaurs from the Upper Cretaceous of Monglia (family

458

Ankylosauridae)]. Trudy Paleontologicheskogo Instituta Akademiy Nauk SSSR 62,

459

51 91. [In Russian]

460

Martinson, G.G., 1982. Pozdnemelovye molliuski Mongolii [Late Cretaceous mollusks of

461

Mongolia]. Trudy Sovmestnaya Sovetsko–Mongol’skaya Paleontologicheskaya

462

Ekspeditsia [Transactions of Joint Soviet-Mongolian Scientific Research and

463

Geological Expedition] 17, 5 76. [In Russian]

464 465

466

Maryañska, T., 1977. Ankylosauridae (Dinosauria) from Mongolia. Palaeontologia Polonica 37, 85 151. Maryañska, T., Osmolska, H., 1975. Protoceratopsidae (Dinosauria) of Asia. Palaeontologia 21

467

468

Polonica 33, 133 181. Maryañska, T., Osmolska, H., 1981. Cranial anatomy of Saurolophus augustirostris with

469

comments on the Asian Hadrosauridae (Dinosauria). Palaeontologica Polonica 42, 5

470

24.

471 472

473

Mlynarski, M., Narmandach, P., 1972. New turtle remains from the Upper Cretaceous of the Gobi Desert, Mongolia. Palaeontologia Polonica 27, 95 101. Norman, D.B., 1984. A systematic reappraisal of the reptile order Ornithischia. In: Reif, W.-

474

E., Westphal, F. (Ed.), Third symposium on Mesozoic terrestrial ecosystems, short

475

papers. Attempto Verlag, Tübingen, Germany, 157 162.

476

Nopcsa, F., 1915. Die dinosaurier der Siebenbürgischen landesteile Ungarns [The dinosaurs

477

of the Transylvanian parts of Hungary]. Mitteilungen Jahrbuch Ungarische

478

Geologische Reichsanstalt 23, 1 26. [In German]

479

Nopcsa, F., 1918. Leipsanosaurus n. gen. ein neuer Thyreophore aus der Gosau. Földtani

480

Közlöny 48, 324 328. [In German]Nowak, R.M., 1991. Walker's Mammals of the

481

World, fifth edition-Volume II. Johns Hopkins University Press, Maryland, USA.

482 483

484 485

486

Osborn, H.F., 1923. Two Lower Cretaceous dinosaurs of Mongolia. American Museum Novitates 95, 1 10. Owen, R., 1842. Report on British fossil reptiles. Reports of the British Association for the Advancement of Science 11, 60 204. Paulina-Carabajal, A., Lee, Y.-N., Kobayashi, Y., Lee, H.-J., Currie, P.J., 2018. Neuroanatomy 22

487

of the ankylosaurid dinosaurs Tarchia teresae and Talarurus plicatospineus from the

488

Upper Cretaceous of Mongolia, with comments on endocranial variability among

489

ankylosaurs. Palaeogeography, Palaeoclimatology, Palaeoecology 494, 135 146.

490 491

492

Penkalski, P., 2018. Revised systematics of the armoured dinosaur Euoplocephalus and its allies. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 287, 261 306. Penkalski, P., Tumanova, T., 2017. The cranial morphology and taxonomic status of Tarchia

493

(Dinosauria: Ankylosauridae) from the Upper Cretaceous of Mongolia. Cretaceous

494

Research 70, 117 127.

495

Perle, A., 1977. O pervoy nakhodke Alektrozavra (Tyrannosauridae, Theropoda) iz pozdnego

496

Mela Mongolii [On the first discovery of Alectrosaurus (Tyrannosauridae, Theropoda)

497

in the Late Cretaceous of Mongolia]. Shinzhlekh Ukhaany Akademi Geologiin

498

Khureelen [Problems of Mongolian Geology] 3, 104 113.

499 500

Prieto-Márquez, A., 2010. Global historical biogeography of hadrosaurid dinosaurs. Zoological Journal of the Linnean Society 159, 435 525.

501

Russell, D. A., Dong, Z., 1993. The affinities of a new theropod from the Alxa Desert, Inner

502

Mongolia, People’s Republic of China. Canadian Journal of Earth Sciences 30, 2107

503

2127.

504 505

506

Seeley, H.G., 1887. On the classification of the fossil animals commonly named Dinosauria. Proceedings of the Royal Society of London 43, 165 171. Sereno, P.C., 1998. A rationale for phylogenetic definitions, with application to the higher 23

507

level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie,

508

Abhandlungen 210: 41 83.

509

Sochava, A.V., 1975. Stratigrafia i litologia vierkhnemelovykh otlozhenii Yuzhnoi Mongolii

510

[Stratigraphy and lithology of the Upper Cretaceous sediments in southern Mongolia].

511

Trudy Sovmestnaya Sovetsko–Mongol’skaya Paleontologicheskaya Ekspeditsia

512

[Transactions of Joint Soviet-Mongolian Scientific Research and Geological

513

Expedition] 13, 113 182. [In Russian]

514

Solounias, N., Moelleken, S.M.C., 1993. Dietary adaptation of some extinct ruminants

515

determined by premaxillary shape. Journal of Mammalogy 74, 1059 1071.

516

Solounias, N., Teaford, M., Walker, A., 1988. Interpreting the diet of extinct ruminants: the

517

case of a non-browsing giraffid. Paleobiology 14, 287 300.

518

Steele, N.A., 1960. Meeting of rhinos of two species. Lammergeyer 1, 40 41.

519

Sukhanov, V.B., 2000. Mesozoic turtles of Middle and Central Asia. In: Benton, M.J.,

520

Shishkin, M.A., Unwin, D.M., Kurochkin, E.N. (Ed.), The Age of Dinosaurs in Russia

521

and Mongolia. Cambridge University Press, Cambridge, 309 367.

522

Sukhanov, V.B., Narmandakh, P., 1975. Cherepakhi gruppy Basilemys (Chelonia,

523

Dermatemydidae) v Azii [New turtles of the group of Basilemys (Chelonia,

524

Dermatemydidae)]. Trudy Sovmestnaya Sovetsko-MongoIskaya

525

Paleontologicheskaya Ekspeditsia [Proceedings Joint Soviet-Mongolian

526

Paleontological Expedition] 2, 94 101. [In Russian]

24

527

Sullivan, R.M., 1999. Nodocephalosaurus kirtlandensis, gen. et sp. nov., a new ankylosaurid

528

dinosaur (Ornithischia: Ankylosauria) from the Upper Cretaceous Kirtland Formation

529

(upper Campanian), San Juan Basin, New Mexico. Journal of Vertebrate Paleontology

530

19, 126 139.

531 532

533

Susana Bargo, M., Toledo, N., Vizcaino, S.F., 2006. Muzzle of South American Pleistocene Ground Sloths (Xenarthra, Tardigrada). Journal of Morphology 267, 248 263. Tsogtbaatar, K., Weishampel, D.B., Evans, D.C., Watabe, M., 2019. A new hadrosauroid

534

(Dinosauria: Ornithopoda) from the Late Cretaceous Baynshire Formation of the Gobi

535

Desert (Mongolia). PLoS ONE 14, e0208480.

536

http://doi.org/10.1371/journal.pone.0208480.

537

Tumanova, T.A., 1987. The armored dinosaurs of Mongolia. The Joint Soviet Mongolian

538

Paleontological Expedition Transaction 32, 1 76. [In Russian, translation by R.

539

Griffith, and edited by K. Carpenter, and T. A. Tumanova.]

540

Tumanova, T.A., 1993. O novom pantsirnov dinozavre iz iugo-vostochnoy Gobi [A new

541

armored dinosaur from Southeastern Gobi]. Paleontologicheskii Zhurnal 27, 92 98.

542

[In Russian]

543

Tumanova, T.A., 2000. Armoured dinosaurs from the Cretaceous of Mongolia. In: Benton,

544

M.J., Shishkin, M.A., Unwin, D.M., Kurochkin, E.N. (Ed.), The Age of Dinosaurs in

545

Russia and Mongolia. Cambridge University Press, Cambridge, 517 532

546 547

Turner, A.H., 2015. A Review of Shamosuchus and Paralligator (Crocodyliformes, Neosuchia) from the Cretaceous of Asia. PLoS ONE 10, e0118116. http://doi.org/ 25

548

10.1371/journal.pone.0118116.

549

Vasiliev, V.G., Volkhonin, V.C., Grishin, G.L., Ivanov, A.K., Marinov, I.A., Mokshancev, K.

550

B., 1959. Geologicheskoye stroyenie Mongolskov Narodnoy Republiki (stratigraha i

551

tektonika) [Geological structure of the People’s Republic of Mongolia (Stratigraphy

552

and Tectonics)]. Gostoptekhizdat, Leningrad. [In Russian]

553

Vickaryous, M.K., Russell, A.P., 2003. A redescription of the skull of Euoplocephalus tutus

554

(Archosauria: Ornithischia): a foundation for comparative and systematic studies of

555

ankylosaurian dinosaurs. Zoological Journal of the Linnean Society 137, 157 186.

556

Vickaryous, M.K., Maryanska, T., Weishampel, D.B., 2004. Ankylosauria. In: Weishampel,

557

D.B., Dodson, P., Osmólska, H. (Ed.), The Dinosauria, second edition. University of

558

California Press, Berkeley and Los Angeles, California, 363 392.

559

Vickaryous, M.K., Russell, A.P., Currie, P.J., Zhao, X.-J., 2001. A new ankylosaurid

560

(Dinosauria: Ankylosauria) from the Lower Cretaceous of China, with comments on

561

ankylosaurian relationships. Canadian Journal of Earth Sciences 38, 1767 1780.

562

Wiersma, J.P., Irmis, R.B., 2018. A new southern Laramidian ankylosaurid, Akainacephalus

563

johnsoni gen. et sp. nov., from the upper Campanian Kaiparowits Formation of

564

southern Utah, USA. PeerJ 6, e5016. http://doi.org/10.7717/peerj.5016.

565 566

567

Zanno, L.E., 2010. A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora). Journal of Systematic Palaeontology 8, 503 543. Zheng, W., Jin, X., Azuma, Y., Wang, Q., Miyata, K., Xu, X., 2018. The most basal

568

ankylosaurine dinosaur from the Albian-Cenomanian of China, with implications for

569

the evolution of the tail club. Scientific Reports 8, 3711. 26

570

http://doi.org/10.1038/s41598-018-21924-7.

571

27

572

Figure captions

573 574

Figure 1. Map showing the locality where the new skull specimens of Talarurus

575

plicatospineus were discovered. (A) Map of Mongolia. (B) Magnified map from A

576

(surrounded by the dotted lined rectangle). (C) Magnified map from B (surrounded by the

577

dotted lined rectangle) with the locality marked by the reference mark ( ).

578 579

Figure 2. Photographs (A C) and line drawings (A’ C’) of new skull specimens of Talarurus

580

plicatospineus in left lateral view. (A A’) MPC-D 100/1354. (B B’) MPC-D 100/1355. (C

581

C’) MPC-D 100/1356. Grey area indicates damaged surface. Abbreviations are as follows:

582

asob, anterior supraorbital caputegulum; en, external naris; inca, internarial caputegulum;

583

laca, lacrimal caputegulum; loca, loreal caputegulum; mso, middle supraorbital caputegulae;

584

mx, maxilla; nasca, nasal caputegulum; nuca, nuchal caputegulum; orb, orbit; pmx,

585

premaxilla; poca, postocular caputegulum; prfca, prefrontal caputegulum; psob, posterior

586

supraorbital caputegulum; qjh, quadratojugal horn; snca, supranarial caputegulum; sqh,

587

squamosal horn.

588 589

Figure 3. Photographs (A C) and line drawings (A’ C’) of new skull specimens of Talarurus

590

plicatospineus in right lateral view. (A A’) MPC-D 100/1354. (B B’) MPC-D 100/1355. (C

591

C’) MPC-D 100/1356. Grey area indicates damaged surface. Abbreviations as in Fig. 2.

592 28

593

Figure 4. Photographs (A C) and line drawings (A’ C’) of new skull specimens of Talarurus

594

plicatospineus in dorsal view. (A A’) MPC-D 100/1354. (B B’) MPC-D 100/1355. (C C’)

595

MPC-D 100/1356. Grey area indicates damaged surface. Abbreviations are as follows: anca,

596

anterolateral nuchal caputegulum; asob, anterior supraorbital caputegulum; fpca,

597

frontoparietal caputegulum; inca, internarial caputegulum; lnca, lateral nuchal caputegulum;

598

loca, loreal caputegulum; mnca, medial nuchal caputegulum; mso, middle supraorbital

599

caputegulae; nasca, nasal caputegulum; nuch, nuchal shelf; path, pathology; prfca, prefrontal

600

caputegulum; prot, protuberance; psob, posterior supraorbital caputegulum; q, quadrate; qjh,

601

quadratojugal horn; snca, supranarial caputegulum; sqh, squamosal horn.

602 603

Figure 5. Photographs (A C) and line drawings (A’ C’) of new skull specimens of Talarurus

604

plicatospineus in palatal view. (A A’) MPC-D 100/1354. (B B’) MPC-D 100/1355. (C C’)

605

MPC-D 100/1356. Grey area indicates damaged surface. Diagonal solid lines indicate

606

unremoved matrix. Abbreviations are as follows: bas, basioccipital; bs, basisphenoid; ch,

607

channel; ect, ectopterygoid; itf, infratemporal fenestra; mx, maxilla; oc, occipital condyle; orb,

608

orbit; par, parietal; para, parasphenoid; parocc, paroccipital process; pmx, premaxilla; pt,

609

pterygoid; qh, quadrate head; qjh, quadratojugal horn; sqh, squamosal horn; v, vomer.

610 611

Figure 6. Photographs (A C) and line drawings (A’ C’) of new skull specimens of Talarurus

612

plicatospineus in anterior view. Grey area indicates damaged surface. (A A’) MPC-D

29

613

100/1354. (B B’) MPC-D 100/1355. (C C’) MPC-D 100/1356. Abbreviations are as follows:

614

asob, anterior supraorbital caputegulum; in bar, internarial bar; inca, internarial caputegulum;

615

laca, lacrimal caputegulum; lnca, lateral nuchal caputegulum; loca, loreal caputegulum; mso,

616

middle supraorbital caputegulae; mx, maxilla; nasca, nasal caputegulum; pmx sin,

617

premaxillary sinus; poca, postocular caputegulum; prfca, prefrontal caputegulum; psob,

618

posterior supraorbital caputegulum; q, quadrate; qjh, quadratojugal horn; snca, supranarial

619

caputegulum.

620 621

Figure 7. Photographs (A C) and line drawings (A’ C’) of new skull specimens of Talarurus

622

plicatospineus in occipital view. Grey area indicates damaged surface. (A A’) MPC-D

623

100/1354. (B B’) MPC-D 100/1355. (C C’) MPC-D 100/1356. Abbreviations are as follows:

624

fm, foramen magnum; nuca, nuchal caputegulum; oc, occipital condyle; parocc, paroccipital

625

process; prot, protuberance; q, quadrate; qjh, quadratojugal horn; socc, supraoccipital; sqh,

626

squamosal horn

627 628

Figure 8. Rostrum of Talarurus plicatospineus, MPC-D 100/1354, in right oblique

629

rostrodorsolateral view. Abbreviations are as follows: cr tm pmx, premaxillary tomial crest; in

630

pmx, premaxillary notch; ipmx s, interpremaxillary suture; mx, maxilla; pmx, premaxilla;

631

pmx sin, premaxillary sinus.

632 633

Figure 9. New maxilla and dentary specimens of Talarurus plicatospineus, MPC-D 100/1355.

30

634

(A A’) Photograph (A) and line drawing (A’) of isolated right maxilla in palatal view. (B B’)

635

Partially preserved right dentary in external (B) and medial (B’) views. Grey area indicates

636

damaged surface. Abbreviations are as follows: mg, Meckalian groove; pro alv, alveolar

637

border.

638 639

Figure 10. Strict consensus of 60 most parsimonious trees. Values beneath nodes indicate

640

Bremer support.

641 642

Figure 11. Time-scaled strict consensus tree of the 60 most parsimonious trees.

643 644

Figure 12. Skull (in left lateral view) and muzzle (in palatal view) comparisons of Talarurus

645

plicatospineus (A A’) to Tsagantegia longicranialis (B B’), and a hypothesized illustration

646

for the different feeding heights between the two taxa (C).

647 648

Figure 13. Skull reconstruction of Talarurus plicatospineus in dorsal (A) and left lateral (B)

649

views.

650

31

651

Table caption

652 653

Table 1. Measurements (mm) of the new skull specimens of Talarurus plicatospineus

654

referred to in the text. Tilde symbol (~) indicates that the measurement is given in terms of

655

the specimen as preserved. ‘L’ refers to a structure from the left side, ‘R’ to a structure from

656

the right side.

657 658

32

Skull dimension Transverse width across: Specimens Craniocaudal Supraorbitals Squamosal Quadratojugal length horns horns MPC-D 301 ~194 ~306 372 100/1354 MPC-D ~262 302 290 ~333 100/1355 MPC-D ~249 265 263 ~234 100/1356

Orbit dimension Width

Height

L: 34 R: ~33 L: 34 R: 49 L: 38 R: 45

L: 35 R: ~34 L: 31 R: 34 L: 33 R: ~35

Highlights
Three new specimens of Talarurus provide new anatomical information about this taxon.
A dispersal event of ankylosaurines from Asia to western North America occurred before the Cenomanian.
Differences of muzzle shape between Talarurus and Tsagantegia suggest a possible niche partitioning among these taxa.

1

Conflicts of Interest Statement Manuscript title:

Additional skulls of Talarurus plicatospineus (Dinosauria: Ankylosauridae) and implications for paleobiogeography and paleoecology of armored dinosaurs

The authors whose names are listed immediately below certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript. Author names:

Jin-Young Park Yuong-Nam Lee Philip J. Currie Yoshitsugu Kobayashi Eva Koppelhus Rinchen Barsbold Octavio Mateus Sungjin Lee Su-Hwan Kim The authors whose names are listed immediately below report the following details of affiliation or involvement in an organization or entity with a financial or non-financial interest in the subject matter or materials discussed in this manuscript. Please specify the nature of the conflict on a separate sheet of paper if the space below is inadequate. Author names:

This statement is signed by all the authors to indicate agreement that the above information is true and correct (a photocopy of this form may be used if there are more than 10 authors):

Author's name (typed)

Author's signature

Date