Archaeohyrax, AMEGHINO, 1897

Billet, Guillaume, Patterson, Bryan & Muizon, Christian De, 2009, Craniodental anatomy of late Oligocene archaeohyracids (Notoungulata, Mammalia) from Bolivia and Argentina and new phylogenetic hypotheses, Zoological Journal of the Linnean Society 155 (2), pp. 458-509 : 460-462

ARCHAEOHYRAX AMEGHINO, 1897

Diagnosis: Members of Archaeohyrax are characterized by the presence of a well-marked labial sulcus on the talonid of m3, an unambiguous synapomorphy of our cladistic analysis. This character is also found as a convergence in hegetotheriids. However, the sulcus is shallower and wider in Archaeohyrax and therefore the two conditions may not be homologous. Other characters may diagnose this clade phylogenetically, but they depend on optimization (see discussion of our phylogenetic analysis).

Type species: Archaeohyrax patagonicus Ameghino, 1897

Type locality: Cabeza Blanca (see below), Chubut, Argentina.

Included species: Archaeohyrax patagonicus Ameghino, 1897 , Archaeohyrax suniensis sp. nov.

ARCHAEOHYRAX SUNIENSIS SP. NOV. FIGURES 1–17 , APPENDIX S1–4 ( TABLES 1, 2, 4)

Archaeohyrax sp. nov. Reguero & Cifelli, 1997. Protarchaeohyrax sp. nov. Reguero & Cifelli, 1997. Archaeohyrax sp. nov. MacFadden et al., 1985.

Holotype: SAL 4: skull and mandible of a young adult, with right I1, I3-M2, left dI1-2, I3, P1-M3, right p1-m2 (m3 is covered with matrix), left p2-m3 ( Figs 2 , 3 ).

Paratypes: MNHN-BOL-V 006730: skull and mandible associated; SAL 183: rostrum with right and left c-m3; MNHN-BOL-V 007147: mandible with right i1, p1-m3 and left i1-m3; YPM-PU 23701: rostrum with right and left p2-m3; SAL 310: mandible with right i2, p2-m3 and left p3-m3.

Referred specimens: See Appendix S1.

Locality: Salla-Luribay, Bolivia.

Diagnosis: Differs from A. patagonicus in: smaller size; smaller facial extent of the premaxillaries, not extending further posteriorly than the level of C; smaller number of teeth exhibiting simultaneously a fossette or fossetid (i.e. P3-M2 & p3-m 2 in A. suniensis ; P2-M3 & p2-m 3 in A. patagonicus ); more hypsodont cheek teeth, almost hypselodont; second mental foramen situated more anteriorly than in A. patagonicus ; stylomastoid foramen situated closer to the tympanohyal recess.

Etymology: from suni, an Aymara word that refers to the highland Altiplano in Bolivia.

Distribution: Deseadan SALMA, late Oligocene. Specimens all come from the Salla section ( MacFadden et al., 1985) but most are from unit 5, Branisella level.

Figures

Figure 1. Teeth measurements, illustration of the method. A, upper cheekteeth, SAL 189, left maxilla with P3-M3. B, lower cheekteeth, SAL 309, right mandible with p3-m2. Mesial to right. Scale bar = 1 cm.

Figure 2. Archaeohyrax suniensis, cranium of the holotype, SAL 4. A, ventral view. B, dorsal view. C, right lateral view. Scale bar = 1 cm.

Figure 3. Archaeohyrax suniensis sp. nov., schematic representation of the dentition of SAL 4. A, upper jaw with right I3-M2, left dI1-2, I3, P1-M3. B, lower jaw with right p1-m2 (m3 is covered with matrix), left p2-m3. Mesial at the top. Scale bar = 1 cm.

Figure 4. Archaeohyrax suniensis sp. nov., paratype, cranium and mandible, MNHN-BOL-V 006730. A, right lateral view. B, dorsal view. Scale bar = 1 cm.

Figure 5. Archaeohyrax suniensis sp. nov., paratype, rostrum, SAL 183. A, ventral view. B, dorsal view. C, right lateral view. Scale bar = 1 cm.

Figure 6. Interpretative and simplified partial reconstruction of the skull of Archaeohyrax suniensis sp. nov., right lateral view, from SAL 4, MNHN-BOL-V 006730 and SAL 183. Scale bar = 1 cm.

Figure 7. Interpretative and simplified reconstruction of the skull of Archaeohyrax suniensis sp. nov., ventral view, from SAL 4, SAL 1010, SAL 183, MNHN-BOL-V 006730 and YPM-PU 23701 (the pterygoid region is highly simplified because it is unknown in many details). Scale bar = 1 cm.

Figure 8. Archaeohyrax suniensis sp. nov., details of the auditory region (right side), SAL 4. A, ventral view. B, postero-lateral (right) view. C, ventro-lateral (right) view. Scale bar = 1 cm.

Figure 9. Archaeohyrax suniensis sp. nov., incomplete posterior part of the skull, SAL 551. Ventral view. Scale bar = 1 cm.

Figure 10. Archaeohyrax suniensis sp. nov., isolated slightly worn premolars. A, YPM-PU 23788, left P4 (?). B, YPM-PU 23789, right P4 (?). Mesial to left and labial at the top. Scale bar = 1 cm.

Figure 11. Archaeohyrax suniensis sp. nov., upper dentition. A, left P3-M3, SAL 189. B, right P3-M3 (reversed), YPM-PU 22056. C, rostrum with right and left P2-M3, YPM-PU 23701. Mesial to the left. Scale bar = 1 cm.

Figure 12. Archaeohyrax suniensis sp. nov., deciduous upper dentition and slightly worn M1. A, left dP3-4, SAL 480. B, right P3, dP4, M1 (reversed), SAL 471. C, right dP2-4, M1 (reversed), YPM-PU 22061. Mesial to left and labial at the top. Scale bar = 1 cm.

Figure 13. Archaeohyrax suniensis sp. nov., partial mandible, MNHN-BOL-V 009682. Scale bar = 1 cm.

Figure 14. Archaeohyrax suniensis sp. nov., lower permanent cheek teeth. A, left p3-m2, SAL 311. B, right p3-m2 (reversed), SAL 309. C, left p3-m3, YPM-PU 22067 (partial). Labial to left and mesial at the top. Scale bar = 1 cm.

Figure 15. Archaeohyrax suniensis sp. nov., paratype, MNHN-BOL-V 007147. Scale bar = 1 cm.

Figure 16. Archaeohyrax suniensis sp. nov., variation of the lower cheek teeth morphology. A, left p3-m2 (reversed), MNHN-BOL-V 006864 (partial). B, right p4-m3, MNHN- BOL-V 003831. C, right p3-m3, MNHN-BOL-V 006136. Lingual to left and mesial at the top. Scale bar = 1 cm.

Figure 17. Archaeohyrax suniensis sp. nov., deciduous lower teeth. A, left dp3-4, m1-2, YPM-PU 21895. B, right dp3-4, SAL 646. Labial to left for A, to right for B, mesial at the top for both. Scale bar = 1 cm.