Huayqueriana, Kraglievich, 1934

Forasiepi, Analía M., MacPhee, Ross D. E., Del Pino, Santiago Hernández, Schmidt, Gabriela I., Amson, Eli & Grohé, Camille, 2016, Exceptional Skull Of Huayqueriana (Mammalia, Litopterna, Macraucheniidae) From The Late Miocene Of Argentina: Anatomy, Systematics, And Paleobiological Implications, Bulletin of the American Museum of Natural History 2016 (404), pp. 1-77 : 9

Huayqueriana cf. H. cristata (Rovereto,

1914)

REFERRED SPECIMEN: IANIGLA-PV 29, cranium with LP1–3, distal half of LP4, RP2–4, and R/ LM2–3 ( figs. 3 , 4 , 10–22 , 24–25 , 27–28 ; tables 2–4).

GEOGRAPHIC AND STRATIGRAPHIC DISTRIBU-

TION: Huayquerías del Este , Río Seco de la Última Aguada (68°27′31.6″W, 33°54′14.5″S), San Carlos Department, Mendoza Province, Argentina ( fig. 1A ). Huayquerías Formation ( fig. 1B ), Huayquerian SALMA (currently correlated with Tortonian-Messinian stages of Late Miocene; Marshall et al., 1986; Yrigoyen, 1994) .

Figures

FIG. 3. Skull of Huayqueriana cf. H. cristata IANIGLA-PV 29 from Huayquerías Formation (Late Miocene, Huayquerian SALMA) in A, right lateral, B, dorsal, and C, ventral views. Abbreviations: C, canine (alveolus); ch, choana; fdv, foramen for frontal diploic vein; fini, foramen interincisivum; fm, foramen magnum; frp, frontal process of squamosal; gf, glenoid fossa; gpf, greater (= major) palatine foramen; I, incisor (alveolus); iof, infraorbital foramen; itc, infratemporal crest; M, molar; mpp, medial palatine process of premaxilla; na, nasal aperture; ncr, nuchal crest; nf, nutrient foramina; oc, occipital condyle; ofs, openings of frontal sinus; P, premolar; pap, paracondylar process of exoccipital; pgp, postglenoid process; plf, palatine fissure; pop, postorbital process of frontal; Pt, pterygoid; rf, foramina for rami temporales; rms, retromolar space; sf, supraorbital foramen; tl, temporal line; V, vomer.

FIG. 4. Skull of Huayqueriana cf. H. cristata IANIGLA-PV 29 in A, right lateral, B, dorsal, and C, ventral views, with measurements (see table 2).

FIG. 10. Virtual parasagittal section through choana of skull of Huayqueriana cf. H. cristata IANIGLA-PV 29. Light gray areas within skull represent unremoved matrix. Caudally-situated vacuity between nasal aperture and nasopharynx is here denoted as “true” nasal cavity (tncav), as it would have acted as the most direct air passageway in life. Primitive nasal cavity (mnv, meatus nasi ventralis) persists as a diverticulum, lacking an external aperture at front of rostrum. Note substantial thickness of rostralmost portions of premaxilla/maxilla at front of long, comparatively gracile rostrum. Other abbreviations: chl, cochlea; crh, position of cerebral hemispheres; cerebral cavity; Ec, ectotympanic; fs, frontal sinus; mnv, meatus nasi ventralis; Mx, maxilla; ns?, possible distorted portion of nasal septum; pafs, parietal extension of frontal sinus; plf, palatine fissure; Pmx, premaxilla; sphs, sphenoidal sinus; t, turbinate fragments in caudal portion of nasal cavity; tncav, true nasal cavity.

FIG. 11. Virtual parasagittal section through skull of Huayqueriana cf. H. cristata IANIGLA-PV 29. Abbreviations: crh, position of cerebral hemispheres (cerebral cavity); Ec, ectotympanic; fs, frontal sinus; M, molar; mnv, meatus nasi ventralis; Mx, maxilla; oc, occipital condyle; P, premolar; pafs, parietal extension of frontal sinus; pap, paracondylar process of exoccipital; Pe, petrosal; Pmx, premaxilla; Pt, pterygoid; ptc, posttemporal canal; sofs, supraoccipital extension of frontal sinus; sphs, sphenoidal sinus; t, turbinate fragments in caudal portion of nasal cavity; tncav, true nasal cavity.

FIG. 12. A–F, Virtual coronal sections of skull of Huayqueriana cf. H. cristata IANIGLA-PV 29. Abbreviations: cc, central canal; M, molar; mnv, meatus nasi ventralis; Mx, maxilla; ns, nasal septum; P, premolar; plf, palatine fissure; Pmx, premaxilla; V, vomer; VNO?, possible sulcus for vomeronasal organ. Asterisk (*) identifies sulcus for vascular structures (see text).

FIG. 13. A–E, Virtual coronal sections of skull of Huayqueriana cf. H. cristata IANIGLA-PV 29. Abbreviations: a, aditus to frontal sinus; crh, position of cerebral hemispheres; fdv, foramen for frontal diploëic vein; fo, foramen ovale; fs, frontal sinus; J, jugal; na, nasal aperture; ob, position of olfactory bulb; otc, orbitotemporal canal; pl, position of piriform lobe; pop, postorbital process of frontal; Psph, presphenoid; Pt, pterygoid; sf, supraorbital foramen with perforating canal; sof, sphenoorbital fissure; Sq, squamosal (zygomatic process); sphs, sphenoidal sinus; t, turbinals. Letter x, identifies canal X for nerve of pterygoid canal and vascular structures (see text).

FIG. 14. Detail of orbit of Huayqueriana cf. H. cristata IANIGLA-PV 29. Abbreviations: etf, ethmoidal foramen; lacf, lacrimal foramen; ocr, orbital crest; opf, optic foramen; otc, orbitotemporal canal; sof, sphenoorbital fissure; spalf, sphenopalatine foramen. Arrow points rostrally.

FIG. 15. Posterior portion of skull of Huayqueriana cf. H. cristata IANIGLA-PV 29, in ventral view. Abbreviations: eam, external acoustic meatus; Ec, ectotympanic; fo, foramen ovale; gf, glenoid fossa; hf, hypoglossal foramen; Hy, hyoid (tympanohyal + stylohyal); m, mastoid process of petrosal; oc, occipital condyle; on, odontoid notch; pap, paracondylar process of exoccipital; pf, piriform fenestra; pgf, postglenoid foramen; pgp, postglenoid process; Pt, pterygoid; smf, stylomastoid foramen. Letter x identifies canal X for nerve of pterygoid canal and vascular structures (see text). Faintly visible on the specimen’s left side is the large sulcus running between the piriform fenestra and canal X.

FIG. 16. Posterior portion of skull of Huayqueriana cf. H. cristata IANIGLA-PV 29, in left ventrolateral view. Abbreviations: eam, external acoustic meatus; Ec, ectotympanic; fm, foramen magnum; fo, to foramen ovale; gf, glenoid fossa; gr, occipital groove; hf, hypoglossal foramen; itc, infratemporal crest; jf, to jugular foramen; m, mastoid process of petrosal; oc, occipital condyle; pap, paracondylar process of exoccipital; pgf, postglenoid foramen; pgp, postglenoid process; pr, promontorium; ptc, posttemporal canal; ptp, posttympanic process of squamosal; smf, stylomastoid foramen; sp, styliform process of ectotympanic.

FIG. 17. A–E, Virtual subhorizontal and subcoronal sections of skull of Huayqueriana cf. H. cristata IANI- GLA-PV 29. Abbreviations: J, jugal; pafs, parietal extension of frontal sinus; pgf, postglenoid foramen; pl, position of piriform lobe; ptc, posttemporal canal; rf, foramina for rami temporales; sfs, septum sinuum frontalium; sofs, supraoccipital extension of frontal sinus; sphs, sphenoidal sinus; Sq, squamosal (zygomatic process); tvs, transverse sinus canal; ve, position of vermis. Letter x identifies canal X for nerve of pterygoid canal and vascular structures (see text).

FIG. 18. Occipital view, skull of Huayqueriana cf. H. cristata IANIGLA-PV 29. Abbreviations: cr, crest; fm, foramen magnum; gr, occipital groove; ncr, nuchal crest; oc, occipital condyle; opr, occipital protuberance; pap, paracondylar process of exoccipital; pgp, postglenoid process; ptc, posttemporal canal. Asterisk (*) identifies canal for vascular structures (see text).

FIG. 19. A–B, Virtual subcoronal sections of basicranium of Huayqueriana cf. H. cristata IANIGLA-PV 29. Abbreviations: Bo, basioccipital; chl, cochlea; Ec, ectotympanic; fenc, fossula fenestrae cochleae; Hy, hyoid (tympanohyal + stylohyal); iam, internal acoustic meatus; me, middle ear space; Pe, petrosal; pr, promontorium; S, stapes; Sq, squamosal; tvs, transverse sinus; VII, passageway of the facial nerve (CN VII); 1, RTPP contacting ectotympanic; 2, crista tympanica?

FIG. 20. Model of right petrosal of Huayqueriana cf. H. cristata IANIGLA-PV 29, based on 3D reconstructions from micro-CT data, in A, tympanic, B, oblique, and C, cerebellar views. In order to adequately expose the facial sulcus (fsl) and track of the greater petrosal nerve (hnpm), it was necessary to digitally remove the bone obscuring structures, including the sidewall of the cavum supracochleare (cs) (see text). Other abbreviations: can, external aperture of cochlear canaliculus; cr.tr, crista transversa; ctpp, caudal tympanic process of petrosal; fai, inferior acoustic foramen; fas, superior acoustic foramen; fenc, fossula fenestrae cochleae; ff, foramen faciale; fsg, foramen singulare; fv, fenestra vestibuli; iam, internal acoustic meatus; jn, notch for jugular foramen; pr, promontorium; rtpp, rostral tympanic process of petrosal; saf, subarcuate fossa; sips, sulcus for inferior petrosal sinus. Asterisk (*) indicates preparation artifact.

FIG. 24. Palate of Huayqueriana cf. H. cristata IANIGLA-PV 29, with detail of dentition in occlusal view. Abbreviations: C, canine (alveolus); ef, enamel fossette; I, incisor (alveolus); M, molar; met, metastyle; mev, metacone valley; mst, mesostyle; P, premolar; pat, parastyle; pav, paracone valley.

FIG 25. Dental histology of left M2 of Huayqueriana cf. H. cristata IANIGLA-PV 29. Coronal section: A, whole surface and B, detail of cementum layer (rectangle in A). Para-occlusal section: C, whole surface and D, detail of cementum layer (rectangle in C). Cementum rest lines indicated by white arrows. Abbreviations: BCJ, bone-cementum junction; CDJ, cementum-dentine junction; cem, cementum; DEJ, dentine-enamel junction; den, dentine; ena, enamel; Mx, maxilla.

FIG. 27. 3D model of skull and inner ear of Huayqueriana cf. H. cristata IANIGLA-PV 29, showing angular relationship between plane of lateral semicircular canal (LSC) and that of skull floor (basal plane), following De Beer (1947).

FIG. 28. Reconstruction of orientation of head of A, Huayqueriana cf. H. cristata IANIGLA-PV 29 and B, horse (following De Beer, 1947), as they might appear in state of normal visual alertness.

FIG. 1. Geographical and stratigraphic context: A, location of Río Seco de la Última Aguada, north-central Mendoza, Argentina; B, integrated stratigraphic column, Río Seco de la Última Aguada, Huayquerías del Este. Huayqueriana cf. H. cristata IANIGLA-PV 29 was recovered from lower levels of Huayquerías Formation (Late Miocene; Huayquerian) exposed along river gorge.