Plastomenus thomasii ( Cope, 1872 )

Fig. 1 Photographs of the cranium of Plastomenus thomasii (AMNH FR 6015). A dorsal view. B ventral view. C left lateral view. D right lateral view

Fig. 2 Photographs of the mandible of Plastomenus thomasii (AMNH FR 6015). A dorsal view. B ventral view.C right lateral view. Note that the posterior part of the left mandibular ramus is preserved, but broken from the main part of the fossil. See 3D renderings for complete fossil

Fig. 3 Three dimensional renderings of the cranium of Plastomenus thomasii (AMNH FR 6015). A dorsal view; B ventral view; C left lateral view; D right lateral view.Note that bones are labelled in bold. boc basioccipital, bt basi tuber, ct cavum tympani, epi epipterygoid, ex exoccipital, f frontals (fused), fpcci foramen posterius canalis carotici interni, fpp foramen palatinum posterius,fsm foramen supramaxillare,fst foramen stapedio-temporale, iqr infolding quadrate ridge, j jugal, labr labial ridge, mx maxilla,op opisthotic, pal palatine,par parietal, pbs parabasisphenoid, ppe processus pterygoideus externus, prf prefrontal, pro prootic,pt pterygoid, q quadrate, qj quadratojugal, soc supraoccipital, sq squamosal, v vomer

Fig. 4 Interpretative line drawings of the cranium of Plastomenus thomasii (AMNH FR 6015).A dorsal view. B left lateral view. C ventral view. Drawings are based on renderings in Fig. 3. Labels indicate incompletely preserved features and our interpretation thereof

Fig. 5 Three dimensional renderings of the interior of the cranium of Plastomenus thomasii (AMNH FR 6015).A anterodorsal view with skull roof elements removed; B dorsal view with skull roof elements removes. Note symmetrical breakage in both opisthotics into the underlying endosseous labyrinth; C posterolateral view into anterior parts of the left orbital fossa;D medial view onto left side of skull.carrf cartilaginous rider fossa, cc canalis cavernosus, ccb canalis caroticus basisphenoidalis, cep cavum epiptericum, crcr crista cranii, dpp dorsal palatine process, epi epipterygoid, faccb foramen anterius canalis carotici basisphenoidalis, faf fossa acustico-facialis, fing foramen internum nervi glossopharyngei fon foramen orbito-nasale, fsm foramen supramaxillare, fst foramen stapedio-temporale, ipc intrapalatine canal, nap narial passage,pfipc posterior foramen into intraplatine canal (for vidian nerve),pr-lsc prootic bar of bone contributing to the lateral semicircular canal, pto processus trochlearius oticum, saf supraalveolar fenestra, sorc suborbital crest, sot septum orbitotemporale,sv sulcus vomeri, tra trabecula, vf vomer foramen

Fig. 6 Computed tomographs through the cranium of Plastomenus thomasii (AMNH FR 6015) and frontal morphology. A–C, cropped µCT slices through the frontal (A–B) and parietal (C) region of the skull roof. D Partial cranium in dorsal view, with prefrontals removed to illustrate the anterior frontal process. Note that bones are labelled in bold.White arrows show examples of traceable suture lines, red arrow indicates region in which an interfrontal suture would have been expected if the bones were not fused. Straight lines in D indicate slice positions for (A–C). apf anterior frontal process,f fused frontals, prff prefrontal facet on frontal

Fig. 7 Three dimensional renderings of the exterior trigeminal region of the cranium of Plastomenus thomasii (AMNH FR 6015). Partial cranium in left anterolateral and slight ventral view, with jugal and quadratojugal removed. Note that bones are labelled in bold. ap antrum postoticum, crcr crista cranii, epi epipterygoid, epp epipterygoid process of quadrate, eun Eustachian notch, f frontals (fused), ica incisura columellae auris, mx maxilla, pal palatine,par-orf orbital fossa of the parietal, par parietal, prf prefrontal, pt pterygoid, pto processus trochlearius oticum, q quadrate, sq squamosal, tf trigeminal foramen

Fig. 8 Three dimensional renderings of the posterior of the cranium of Plastomenus thomasii (AMNH FR 6015). A posterior view; B left posterolateral and slight ventral view.Note that bones are labelled in bold. boc basioccipital, bt basi tuber, csoc crista supraoccipitalis, eun Eustachian notch, ex exoccipital,fp foramen jugulare posterius, fpcci foramen posterius canalis carotici interni, iqr infolding quadrate ridge, occ occipital condyle,op opisthotic, par parietal, pop paroccipital process, pt pterygoid, q quadrate, soc ssupraoccipital,sq squamosal

Fig. 9 Three dimensional renderings of the partial basicranium of Plastomenus thomasii (AMNH FR 6015) with reconstructed arteries and nerves. A anterodorsal view onto parabasisphenoid and left pterygoid; B dorsal view. Note that bones are labelled in bold. Nerves are reconstructed in yellow, arteries in red, and veins in blue. abng abducens nerve groove, ccb canals caroticus basisphenoidalis, cera cerebral artery, ds dorsum sellae, ica internal carotid artery,‘lata’lateral artery (possible palatine artery or pseudopalatine artery or mandibular artery), lhv lateral head vein, pbs parabasisphenoid, pt, pterygoid, rbsp rostrum basisphenoidale, scav sulcus cavernosus, st sella turcica, tra trabecula, VI abducens nerve,VIIvi vidian branch of facial nerve

Fig. 10 Three dimensional renderings of the right endosseous labyrinth of Plastomenus thomasii (AMNH FR 6015). A lateral view; B dorsal view; C anterior view; D posterior view. Note that the fenestra ovalis region is incomplete due to breakage along the prootic and opisthotic. Also, the endocast of the fenestra perilymphatica is incomplete due to breakage. asc anterior semicircular canal, cc common crus, fav foramen aquaducti vestibuli,fov fenestra ovalis,fpl fenestra perilymphatica, lam lateral ampulla,lsc lateral semicircular canal, psc posterior semicircular canal, scc secondary common crus

Fig. 11 Three dimensional renderings of the mandible of Plastomenus thomasii (AMNH FR 6015). A left lateral view; B right lateral view; C medial view of left mandibular ramus;D medial view of right mandibular ramus; E dorsal view; F posterodorsal view of posterior end of left mandibular ramus; G posterodorsal view of posterior end of right mandibular ramus. Medial views were achieved by artificially cutting the dentary along the symphysis. Note that bones are labelled in bold. Dashed lines circumscribe foramina to highlight their positions. aap anterior angular process, add adductor fossa,adp ascending dentary process, art articular,as articulation surface, cor coronoid, corp coronoid process, d dentary, dsf dorsal surangular foramen, dsym dorsal symphyseal mount, fai foramen alveolare inferius, fat foramen auriculotemporalis,fdfm foramen dentofaciale majus,fimm foramen intermandibulare medius, fM fossa Meckelii, matf medial auriculotemporal foramen, pre prearticular, rap retroarticular process, secf surangular ectocondylar flange, sM sulcus Meckelii, ssytr spatulate symphyseal triturating surface, syg symphyseal groove