92. Astragalonavicular Facet Extends on Medial Side of Astragalar Head: 0 = Absent; 1 = Medial
Character list
Yalkaparidon can be scored for 113 characters (80 craniodental, 33 tarsal) of the morphological matrix used here, which is modified from Beck (2012; see also Horovitz and Sánchez-Villagra 2003; Sánchez-Villagra et al. 2007; Beck et al. 2008; Horovitz et al. 2008, 2009; Abello and Candela 2010). We also revise some scoring decisions for other terminals. Characters marked by an asterisk (*) were ordered. Two versions of the morphological matrix were created: one in which Yalkaparidon was scored for both craniodental and tarsal characters (which assumes that the tarsal specimens described here are indeed referable to Yalkaparidon), and second in which Yalkaparidon was scored for craniodental characters only. Both versions of the matrix are available for download from Morphobank ( Project 929) and from Dryad ( doi: 10.5061/dryad.25nt8).
91. Astragalus, angle between medial and lateral facets for tibia*: 0 = 90 degrees; 1 = intermediate; 2 = 180 degrees.
Yalkaparidon: 1
92. Astragalonavicular facet extends on medial side of astragalar head: 0 = absent; 1 = medial.
Yalkaparidon: 0
93. Astragalonavicular facet extends on ventromedial area of astragalar head: 0 = absent; 1 = present.
Yalkaparidon: 1
94. Dimensions of astragalonavicular facet of astragalus in distal view: 0 = transversely wider; 1 = dorsoventrally wider.
Yalkaparidon: 0/1
Notes: The transverse width and dorsoventral height of the astragalonavicular facet are approximately equal in Yalkaparidon (Figs. 14-15), which has therefore been scored as ‘0/1’ for this character.
95. Astragalar medial plantar tuberosity (ampt) visibility in dorsal view: 0 = not visible; 1 = visible.
Yalkaparidon: 1
96. Astragalus, angle between facet for fibula and lateral facet for tibia*: 0 = 180 degrees; 1 = intermediate; 2 = 90 degrees.
Yalkaparidon: 1
97. Astragalar neck: 0 = absent; 1 = present.
Yalkaparidon: 1
98. Relative width of astragalar head and neck: 0 = neck narrower or as wide as head; 1 = neck wider than head.
Yalkaparidon: 1
99. Astragalar sustentacular facet medial extent: 0 = does not reach medial edge of neck; 1 = reaches medial edge of neck.
Yalkaparidon: 0
100. Astragalonavicular facet position relative to facets for tibia: 0 = anterior to facets for tibia; 1 = medial relative to facets for tibia.
Yalkaparidon: 0
101. Astragalar canal: 0 = absent; 1 = present.
Yalkaparidon: 1
102. Ectal facet of astragalus major dimension orientation: 0 = straight; 1 = posteromedial to anterolateral.
Yalkaparidon: 1
103. Ectal facet of astragalus position in ventral view: 0 = extending up to posterior edge of astragalus; 1 = subterminal.
Yalkaparidon: 0
104. Astragalus, ridge between medial and lateral astragalotibial facets: 0 = absent; 1 = present.
Yalkaparidon: 1
105. Astragalus, ridge between lateral astragalotibial and astragalofibular facets: 0 = absent; 1 = present.
Yalkaparidon: 1
106.Medial astragalotibial facet of astragalus, posterior extent: 0 = does not reach posterior edge of lateral astragalotibial facet, 1= equal in anteroposterior length as lateral astragalotibial facet.
Yalkaparidon: 0
107. Astragalonavicular facet connection with sustentacular facet on astragalus: 0 = absent; 1 = present.
Yalkaparidon: 0+1
Notes: The astragalonavicular facet is clearly connected to the sustentacular facet in some astragalar specimens (e.g., QMF40096) but not in others (e.g., QMF39989).
108. Calcaneal sustentacular facet on sustentaculum*: 0 = no sustentaculum (facet is located in calcaneal body); 1 = on sustentaculum; 2 = facet is located above level of sustentaculum, which becomes the medial process.
Yalkaparidon: 1
110. Ectal facet longest dimension*: 0 = anteromedial to posterolateral; 1 = straight; 2 = posteromedial to anterolateral.
Yalkaparidon: 0/1
Notes: The condition in Yalkaparidon appears to be intermediate between states 0 and 1, and hence it has been scored as ‘0/1’ for this character.
112. Calcaneal peroneal tubercle: 0 = absent; 1 = present.
Yalkaparidon: 1
113. Calcaneal peroneal tubercle shape: 0 = protuberance; 1 = laminar; 2 = process.
Yalkaparidon: 0
114. Calcaneal peroneal tubercle position*: 0 = protruding anteriorly beyond calcaneocuboid facet; 1 = anterior, non-protruding; 2 = at a distance from anterior end of calcaneus.
Yalkaparidon: 2
115. Calcaneal sustentacular facet (anterior part) mesiolateral orientation: 0 = medial; 1 = mediodorsal or dorsal.
Yalkaparidon: 1
116. Calcaneal sustentacular facet anteroposterior orientation: 0 = dorsal; 1 = 45 degrees dorsoanteriorly.
Yalkaparidon: 1
117. Calcaneal sustentacular facet anteroposterior convexity: 0 = concave or flat; 1 = convex.
Yalkaparidon: 0
119. Calcaneal plantar tubercle: 0 = absent; 1 = present.
Yalkaparidon: 1
120. Calcaneal sustentacular facet and ectal facet merging*: 0 = separate; 1 = with narrow connection; 2 = merged.
Yalkaparidon: 1
121. Calcaneal sustentacular facet anterior edge: 0 = anterior to ectal facet; 1 = equal or posterior to ectal facet.
Yalkaparidon: 0
122. Calcaneal facet for fibula: 0 = absent; 1 = present.
Yalkaparidon: 0
123. Calcaneal facet for fibula orientation: 0 = lateral; 1 = dorsal.
Yalkaparidon: -
124. Calcaneocuboid facet of the calcaneum*: 0 = not subdivided into separate facets; 1 = subdivided into distal (CaCud) and proximal (CaCup) facets; 2 = subdivided into auxiliary (CaCua), lateral (CaCul), and medial (CaCum) facets.
Yalkaparidon: 2
125. Calcaneal sustentacular facet reaches anterior end: 0 = absent; 1 = present.
Yalkaparidon: 1
126. Calcaneal accessory facet anterior to sustentacular facet: 0 = absent; 1 = present.
Yalkaparidon: 0
147. Number of upper incisors*: 0 = five; 1 = four; 2 = three; 3 = two; 4 = one.
Yalkaparidon: 2
149. Number of upper molars*: 0 = four; 1 = three; 2 = none.
Yalkaparidon: 0
Notes: This character was scored based on the revised interpretation presented here that four molars are present in Yalkaparidon.
150. Upper molar M2 shape: 0 = triangular or semi-triangular; 1 = rectangular or semi-square.
Yalkaparidon: -
Notes: Loss of all parts of the upper molar lingual to the metacone means that we consider this character to be inapplicable for Yalkaparidon.
151. Paracone and metacone placement in M2: 0 = medial or buccal; 1 = buccal margin.
Yalkaparidon: 0
Notes: This character was scored on the basis that the major cusp of the upper molars is the metacone (see Dental Description).
152. Paracone versus metacone size in M2*: 0 = pa > me; 1 = pa equals to me; 2 = pa < me; 3 = paracone completely supressed
Notoryctes: 3
Yalkaparidon: 3
Notes: We add an additional state (3) on the assumption that the paracone has been completely suppressed in Notoryctes (see Archer et al. 2011) and also Yalkaparidon (see Dental Description of this paper for discussion as to why we believe the lingual cusp in Yalkaparidon is probably the metacone).
153. Centrocrista shape: 0 = linear; 1 = V-shaped; 2 = absent.
Yalkaparidon: -
Notes: Loss of the paracone in Yalkaparidon (see character 152) renders this character inapplicable.
154. Metaconule: 0 = absent or not well developed; 1 = well developed or enlarged.
Yalkaparidon: -
Notes: This character is inapplicable for Yalkaparidon because the entire region of the tooth lingual of the metacone is missing.
155. Trigonid versus talonid width: 0 = trigonid wider than talonid; 1 = trigonid subequal to talonid or trigonid narrower than talonid.
Yalkaparidon: -
Notes: Loss of the entire talonid in Yalkaparidon renders this character inapplicable for this taxon.
156. Paraconid on lower molars: 0 = absent; 1 = present.
Yalkaparidon: 1
157. Intersection of cristid obliqua with trigonid on m2: 0: lingual to protocristid notch; 1: labial to protocristid notch.
Peradectidae: 1
Yalkaparidon: -
Notes: Peradectidae is scored as ‘1’ based on Peradectes (see Williamson et al. 2012).
158. Upper incisor arcade shape*: 0 = U-shape; 1 = broad V-shape; 2 = long, narrow V-shape.
Yalkaparidon: 1
159. P1: 0 = absent; 1 = present to greatly reduced.
Yalkaparidon: 0
160. p2*: 0 = absent; 1 = greatly reduced; 2 = present.
Peradectidae: 2
Yalkaparidon: 0/1
Notes: Peradectidae is scored as ‘2’ based on Peradectes (see Simpson 1935). Yalkaparidon has been scored as ‘0/1’ on the basis that is possible that one of the tiny unicuspid teeth between i1 and m1 in Y. coheni may be p2.
161. P2*: 0 = absent; 1 = greatly reduced; 2 = present.
Yalkaparidon: 0
162. Upper incisors spatulate: 0 = no; 1 = yes.
Yalkaparidon: 0
163. Size I3 vs. I2*: 0 = I3 > I2; 1 = I3 equal to I2; 2 = I3 < I2.
Yalkaparidon: 1
164. Procumbent gliriform lower anteriormost incisor: 0 = absent; 1 = present.
Caenolestes: 1
Palaeothentes: 1
Yalkaparidon: 1
Notes: Yalkaparidon exhibits an enlarged (‘gliriform’) procumbent lower anterior incisor. Among the other terminals including in the matrix, a similar morphology is seen in the caenolestids Caenolestes and Palaeothentes and diprotodontians. However, the gliriform lower incisor of caenolestids and diprotodontians has been argued to be non-homologous (Ride 1962), and this hypothesis has been followed in previous versions of this matrix (Horovitz and Sánchez-Villagra 2003: character 167; see also Sánchez-Villagra et al. 2007; Beck et al. 2008; Horovitz et al. 2008, 2009; Abello and Candela 2010; Beck 2012). Nevertheless, the homology of the gliriform incisor in caenolestids is, in fact, uncertain (Luckett and Hong 2000), and it is impossible to identify which locus this tooth represents in Yalkaparidon based on available specimens. To allow comparison of this feature between caenolestids, diprotodontians, and Yalkaparidon, we have modified this character to simply reflect whether a procumbent gliriform lower anteriormost incisor is present or absent, without reference to specific dental loci. Thus, the caenolestids Caenolestes and Palaeothentes, diprotodontians, and Yalkaparidon are all scored as ‘1’ for this character here.
165. Hypoconulid absent or present: 0 = absent; 1 = present.
Yalkaparidon: -
Notes: As for characters 155 and 157, this character is inapplicable for Yalkaparidon because the talonid has been lost.
166. c1*: 0 = absent; 1 = greatly reduced; 2 = retained.
Yalkaparidon: 0/1
Notes: Yalkaparidon has been scored as ‘0/1’ for this character on the basis that is possible that one of the tiny unicuspid teeth between i1 and m1 in Y. coheni may be a canine.
167. C1: 0 = caniniform or premolariform; 1 = reduced or absent.
Yalkaparidon: 1
168. Number of roots on C1: 0 = two; 1 = one.
Yalkaparidon: 1
169. Lower i2 (i3 of Hershkovitz 1982, 1995) staggered or not staggered: 0 = staggered; 1 = not staggered.
Peradectidae: ?
Notes: Peradectidae was scored as ‘0’ for this character by Horovitz et al. (2009; see also Beck 2012), presumably based on the presence of staggering in ‘Peradectes-like’ metatherian specimens from the middle Eocene Messel pit (see Kurz 2007). However, it has not been unambiguously demonstrated that these Messel specimens are indeed peradectids, and hence Peradectidae is scored as ‘?’ here.
170. Bunolophodonty or lophodonty developed: 0 = no; 1 = yes.
Yalkaparidon: 0
171. Selenodonty developed: 0 = no; 1 = yes.
Yalkaparidon: 0
173. Parietal-alisphenoid or squamosal-frontal contact on braincase: 0 = parietal-alisphenoid; 1 = squamosal-frontal.
Yalkaparidon: 0
Notes: Wroe et al. (1998) stated that squamosal-frontal contact is present in Yalkaparidon, but this interpretation does not take into account the fact that much of the bone (particularly the alisphenoid) forming the lateral wall of the braincase has flaked off in QMF13008. When intact, the alisphenoid would have contacted the parietal in QMF13008 (see Fig. 7).
175. Angular process medially inflected: 0 = no; 1 = yes.
Peradectidae: 1
Yalkaparidon: 1
Notes: Peradectidae is scored as ‘1’ based on Peradectes.
176. Mandibular symphysis fused: 0 = no; 1 =yes.
Yalkaparidon: 0
177. Bones surrounding maxillary foramen in the orbit: 0 = maxilla + lacrimal; 1 = maxilla only.
Yalkaparidon: 0
Notes: Although the lacrimal is not preserved in any known Yalkaparidon specimen, the extremely narrow maxillary roof of the maxillary foramen strongly suggests that the lacrimal also contributes to the roof of this foramen (see the “Maxilla” section of “Cranial Description”).
178. Posteriormost point of premaxillo-nasal contact: 0 = anterior or at the canine; 1 = posterior to the canine.
Yalkaparidon: 1
182. Alisphenoid tympanic wing*: 0 = absent; 1 = poorly developed; 2 = moderately developed; 3 = well developed, extending to or near posterior lacerate foramen and paroccipital process.
Yalkaparidon: 1/2
Notes: Both left and right alsiphenoid tympanic processes are broken in QMF13008, and no other specimen preserves them; hence, this character cannot be scored unequivocally for Yalkaparidon. However, it is clear from QMF13008 that this process was present but did not extend as far as the paroccipital process, and so Yalkaparidon has been scored as 1/2 for this character.
184. Postglenoid process: 0 = absent; 1 = present.
Yalkaparidon: 1
Notes: The postglenoid process is extremely weak in Yalkaparidon, but is still identifiable as a discrete structure (unlike in Ornithorhynchus, Tachyglossus, or Vincelestes).
186. Fusion of ectotympanic with other bones of the skull: 0 = no; 1 = yes.
Yalkaparidon: 0
Notes: This character was scored based on the fact that the ectotympanic is missing in QMF13008 and there is no evidence for fusion of the ectotympanic to any other basicranial structure.
187. Postglenoid foramen: 0 = absent; 1 = present.
Yalkaparidon: 1
188. Postglenoid foramen position: 0 = located posterior to postglenoid process; 1 = even with postglenoid process; 2 = anterior to postglenoid process and frequently encircled by squamosal.
Yalkaparidon: 0/1
Notes: In QMF13008, the anterior part of the postglenoid foramen is level with the postglenoid process, but the posterior part is posterior to this process (Fig. 8); hence Yalkaparidon has been scored as 0/1 for this character.
189. Position of incisura tympanica: 0 = caudal or caudodorsal; 1 = located dorsally or anterior crus and posterior crus unite dorsally.
Peradectidae: ?
Notes: Peradectidae was scored as ‘0’ for this character by Horovitz et al. (2009; see also Beck 2012), presumably based on the apparent preservation of the ectotympanic in ‘Peradectes-like’ metatherian specimens from the middle Eocene Messel pit (see Kurz 2007) – the holotype and only known specimen of Mimoperadectes houdei (USNM 482355) does not preserve the ectotympanic (see Horovitz et al. 2009). However, it has not been unambiguously demonstrated that the Messel specimens are indeed peradectids, and hence Peradectidae is scored as ‘?’ here.
190. Size of incisura tympanica: 0 = narrow or absent; 1 = wide.
Peradectidae: ?
Notes: As for character 189, Peradectidae was scored as ‘1’ for this character by Horovitz et al. (2009; see also Beck 2012), presumably based on the apparent preservation of the ectotympanic in ‘Peradectes-like’ metatherian specimens from the middle Eocene Messel pit (see Kurz 2007) – the holotype and only known specimen of Mimoperadectes houdei (USNM 482355) does not preserve the ectotympanic (see Horovitz et al. 2009). However, it has not been unambiguously demonstrated that the Messel specimens are indeed peradectids, and hence Peradectidae is scored as ‘?’ here.
191. Foramen ovale position: 0 = lamina obturans / other bones; 1 = alisphenoid / petrosal; 2 = just alisphenoid; 3 = alisphenoid / squamosal.
Yalkaparidon: 1
193. Transverse canal foramen: 0 = absent; 1 = anterior to carotid foramen; 2 = perforating pterygoid fossa; 3 = confluent with carotid foramen; 4 = posterior to carotid foramen.
Yalkaparidon: 4
Notes: Yalkaparidon is apparently unique within Metatheria in that the transverse canal foramen is clearly posterior to the carotid foramen (see Fig. 8). This morphology has been scored as an additional state (4), which is an autaporphy of Yalkaparidon in the current analysis.
194. Intramural transverse canal: 0 = absent; 1 = present.
Yalkaparidon: 0
Notes: See the “Basisphenoid” section of “Cranial Description.”
196. Medial process of squamosal: 0 = absent; 1 = present.
Notes: This character has been deleted because it overlaps with character 258 (contribution of squamosal to hypotympanic sinus roof). All taxa have therefore been scored as inapplicable for this character.
197. Shape of nasals: 0 = posteriorly expanded; 1 = not posteriorly expanded.
Yalkaparidon: 0
Notes: See the “Nasals” section of “Cranial Description.”
198. Septomaxilla: 0 absent; 1 = present.
Yalkaparidon: 0
199. Palatal vacuities*: 0 = absent or just small foramina; 1 = present, restricted to palatine bones; 2 = present in both palatine and maxillary bones.
Yalkaparidon: 2
Notes: It is unclear precisely how large the palatal vacuities of Yalkaparidon were, but examination of QMF13008 and isolated maxillary specimens suggests that vacuities were present and were enclosed by both the palatine and maxilla, i.e., maxillopalatine fenestrae sensu Voss and Jansa (2003, 2009) were present.
200. Premaxilla, palatal process: 0 = does not; 1 = does reach canine alveolus or it is immediately posterior to it.
Yalkaparidon: 0
202. Hypoglossal foramina* 0 = confluent with jugular foramen; 1 = one; 2 = two or more.
Yalkaparidon: 2
203. Optic foramen: 0 = absent; 1 = present.
Yalkaparidon: 0
204. Masseteric canal and dental canal in mandible: 0 = masseteric canal does not open into dental canal; 1 = masseteric canal opens into dental canal.
Yalkaparidon: 0
219. Cavum supracochleare: is not roofed dorsally by the petrosal, and a depression in the anterior lamina for the geniculate ganglion is visible in dorsal view (0); is entirely enclosed within the petrosal (1); is not floored ventrally, such that there is no secondary facial foramen (2).
Yalkaparidon: 1
220. Cavum epiptericum floored by: petrosal (0), petrosal and alisphenoid (1); primarily or exclusively by alisphenoid (2); primarily open as piriform fenestra (3).
Yalkaparidon: 2
Notes: Scored based on the isolated petrosal QMF52958 (Fig. 9).
221. Fossa subarcuata: deep (0); extremely shallow (1).
Yalkaparidon: 0
Notes: Scored based on the isolated petrosal QMF52958 (Fig. 9).
222. Pars mastoidea: not extensively pneumatised (0); extensively pneumatised and composed of cancellous bone (1).
Yalkaparidon: 0
224. Anterior lamina of petrosal exposure on the lateral wall of the braincase: present and large (0); rudimentary (1); absent (2).
Yalkaparidon: 2
227. Internal acoustic meatus: with prefacial commissure at least 50% the width of the internal acoustic meatus (0); with prefacial commissure less than 50% the width of the internal acoustic meatus (1).
Yalkaparidon: 1
Notes: Scored based on the isolated petrosal QMF52958 (Fig. 9).
228. Deep groove for internal carotid artery excavated on anterior pole of promontorium: absent (0); present (1).
Yalkaparidon: 0
229. Deep and large fossa for the tensor tympani muscle excavated on the anterolateral aspect of promontorium, creating a battered ventral surface of the promontorium: absent (0); present (1).
Yalkaparidon: 0
230. Epitympanic wing of petrosal: absent (0); present (1).
Yalkaparidon: 1
231. Epitympanic wing of petrosal: flat (0); confluent with bulla (1).
Yalkaparidon: 0
232. Lateral flange: large and lateral to promontorium (0); greatly reduced or absent (1).
Yalkaparidon: 1
233. Broad shelf of bone surrounding fenestra cochleae and making a separation between it and aqueductus cochleae: absent (0); present (1).
Yalkaparidon: 0
234. Rostral tympanic process of petrosal: absent (0); present as a distinct crest or erect process (1).
Yalkaparidon: 1
235. Rostral tympanic process of petrosal: forms an anterolaterally directed wing, sometimes contacting the ectotympanic, that does not extend on the whole length of the promontorium (0); that does extend on the whole length of the promontorium (1).
Yalkaparidon: 1
236. Tympanic aperture of hiatus Fallopii*: dorsal (0); intermediate (1); ventral (2).
Yalkaparidon: 1
Notes: Scored based on the isolated petrosal QMF52958 (Fig. 9).
237. Stylomastoid foramen formed by the caudal tympanic process of the petrosal: absent (0); present (1).
Yalkaparidon: 0
238. Inferior petrosal sinus: intrapetrosal (0); between petrosal, basisphenoid and basioccipital (1); endocranial (2).
Yalkaparidon: 1
239. Mastoid exposure: contacts the parietal (0); does not contact the parietal (1); greatly reduced, forming a dorsoventrally narrow band on the ventrolateral corner of the posterior face of the cranium (2).
Yalkaparidon: 0
240. Mastoid process: large and vertical (0); small, slanted, and nodelike, on the posterolateral border of the stylomastoid notch and continuous with squamosal (1); indistinct to absent (2).
Yalkaparidon: 2
241. Caudal tympanic process of petrosal: absent (0); present (1).
Yalkaparidon: 1
242. Caudal tympanic process of petrosal: forms a small crest that does not wholly floor the post-promontorial tympanic sinus (0); forms an expanded lamina that floors the post-promontorial tympanic sinus (1).
Yalkaparidon: 0
243. Petrosal plate: absent (0); present (1).
Yalkaparidon: 0
244. Fossa incudis and epitympanic recess: continuous (0); separated by a distinct ridge (1).
Yalkaparidon: 0
245. Petrosal crest: absent (0); present (1).