Protemnodon viator Kerr & Camens & Van Zoelen & Worthy & Prideaux 2024, sp. nov.
Creators: name: Kerr, Isaac A. R.
name: Camens, Aaron B.
name: Van Zoelen, Jacob D.
name: Worthy, Trevor H.
name: Prideaux, Gavin J.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Diprotodontia
Macropodidae
Protemnodon
Protemnodon viator

description: Protemnodon viator sp. nov.
LSID of new species: urn:lsid:zoobank.org:act: A3A47C56-B6B7-4C0A-853F-B57FEC5A6983
Protemnodon brehus (Owen); Helgen et al. (2006), p. 303, appendix 2. See also Janis et al. (2020), table 1; Jones et al. (2021), table 1; Wagstaffe et al. (2022), figs 6 & 7, table 1; Janis et al. (2023), SI table 1.
Protemnodon sp. cf. brehus; Flannery & Gott (1984), pp. 405, 407 & 408, figs 11 & 12.
Protemnodon sp. cf. roechus; Flannery (1984), p. 125, table 1.
Holotype: SAMA P59552; near complete skeleton, lacking sacrum, caudal vertebrae Ca3, 4 and 15+, L pisiform, hamatum, capitatum, trapezoid, trapezium and four manual phalanges, and L middle pedal phalanx V (Fig. 59). Found wholly articulated and collected by A. B. Camens in 2019.
Type locality:
SIAM Site 5, 29.7832°S, 140.1164°E, Lake Callabonna Fossil Reserve, northeastern South Australia. Lacustrine late Pleistocene fossil deposits (deposited during a drought phase commencing about 48 ka in sediments 54.2–50.4 ka) (McInerney et al. 2022). Worthy and Camens et al. in 2013, 2014, 2018 and 2019 led joint Flinders University– University of Adelaide expeditions to the lake, recovering a wealth of fossil material including all the type material listed for this species. Lake Callabonna is an ephemeral salt-lake in the far southeast of the Lake Eyre Basin that forms part of a chain from Lake Gregory to Lake Frome, curving southeasterly around the northern margins of the Gammon Ranges.
Paratypes:
SAMA P53835a (SIAM Site 4, Lake Callabonna, 29.7879°S, 140.1161°E) partial articulated skeleton (preserved with SAMA P53835b); lacking atlas vertebra, sacrum, caudal vertebrae, R forelimb distal to the radial facet on the ulna, and the entire L side except a partial L pes.
SAMA P53835b partial articulated juvenile skeleton in situ with SAMA P53835a; cranium with I1–3 and DP2–M1, mandible with i1 and dp2–m1; lacking thoracic vertebrae T 4–14 and lumbar, sacral and caudal vertebrae, L ilium, L distal tibia and L pes, and entire R side except the pelvis and manual phalanges.
SAMA P53836 (SIAM Site 5, Lake Callabonna 29.7338°S, 140.1305°E) partial skeleton; cranium, L dentary, R i1; partial L humerus, partial L ulna and distal epiphysis, proximal radius, partial L pisiform, proximal manual phalanx V; R distal fibular epiphysis, L calcaneal fragment, and L middle pedal phalanx V.
SAMA P59550 (Tedford Site, Lake Callabonna, 29.7820°S, 140.1348°E) partial skeleton; cranium with partial L I1 and P3–M4, L and partial R dentaries preserving i1 and p3–m4; vertebrae C1 and partial C2, partial Ca1–4 and 6–9; L scapula, L humerus, proximal L ulnar fragment and R ulna, partial R radius, R metacarpal III, articulated L metacarpals I– III and proximal–distal manual phalanges I– III; partial LR pelvis, proximal LR femoral fragments, partial R femur, partial LR fabellae, articulated L tibia and fibula, distal R tibial fragments, distal R fibular fragments, LR calcanei, LR tali, partial R cuboid and L cuboid fragment, partial LR naviculars, R and partial L ectocuneiforms, LR proximal metatarsals IV, L and proximal R metatarsals V, proximal plantar sesamoid for metatarsals IV and V, partial LR proximal–distal pedal phalanges IV and V.
SAMA P59548 (SIAM Site 5, 29.7780°S, 140.1403°E) partial cranium with I1–3 and P3–M4, L dentary with i1 and p3–m4.
Referred specimens:
Western Australia
Christmas Creek, Mueller Ranges: WAM 68.10.77 L metatarsal IV; WAM 68.10.78 L metatarsal V; WAM 68.10.80 proximal pedal phalanx V; WAM 68.10.82 proximal pedal phalanx IV.
Quanbun Station, Fitzroy Crossing: WAM 66.7.9 R upper molar; WAM 63.11.8 R i1; WAM 82.7.36 middle pedal phalanx IV.
South Australia
Lake Callabonna Fossil Reserve: SAMA P59551 partial skeleton. SIAM 77 ‘A01’ partial cranium; SIAM 37 ‘A07’ partial cranium and R dentary; SIAM 43 ‘A08’ R dentary; SIAM 77 ‘A02’ partial L dentary; SIAM 37 ‘A10’ L i1, R humerus and L femur; SIAM 37 ‘A09’ L I1, R i1, and L radius; SIAM 37 ‘A11’ L radius; SIAM 37 ‘A03/A05’ R calcaneus, cuboid, and metatarsals IV and V; SIAM 37 ‘A04/ A06’ R calcaneus, cuboid, and metatarsal IV; AMNH FM 145501 L calcaneus, talus, metatarsals IV and V, and pedal phalanges IV and V. NMNH PAL 498886 R calcaneus, cuboid, talus, metatarsal IV, partial metatarsal V, and middle and distal pedal phalanges IV and V.
Cooper’s Last, Cooper Creek: SAMA P46824 partial R ulna.
Malkuni Waterhole, Cooper Creek: SAMA P54629 axis vertebra; SAMA P25074 L ilium; SAMA P25098 articulated partial L pes; SAMA P50549 R calcaneus.
Waralamanko Waterhole, Cooper Creek: SAMA P25187 partial L ulna; SAMA P25203 partial L femur.
Site ‘075’ (- 28.5609°S, 138.0394°E), Cooper Creek: SAMA P54425 R calcaneus.
Lookout Locality, Warburton River: SAMAP 52601partial juvenile L dentary; SAMA P25290 L metatarsal V.
Mulyanna Site, Warburton River: SAMA P25455 L tibia.
Main Fossil Chamber, Victoria Fossil Cave, Naracoorte: SAMA P59545 R metatarsal V.
New South Wales
Wellington Caves, Wellington (site unknown): AM F16490 neurocranium; AM F104147 R metatarsal IV.
Victoria
Site 1534, Level 2, Lancefield Swamp: NMV P40385 L metatarsal V.
Spring Creek Locality: NMV P42526 partial cranium and L dentary; NMV P173087 L femur and proximal tibial epiphysis.
Specific diagnosis:
Protemnodon viator sp. nov. is differentiated from other species of Protemnodon by multiple autapomorphies and a unique combination of cranial and postcranial characteristics. The cranium of the species is separated from both P. mamkurra sp. nov. and P. anak, the two species of Protemnodon for which the orbit is known, by having a more anteroventrally slanted orbit in lateral view. The forelimb differs from all other species of Protemnodon in having: a radius with a more proximally situated cranial ridge; and more gracile metacarpals. The hindlimb differs from all other species of Protemnodon in having: a more robust femur, with a more raised, more distinct intercondylar crest and a more medially projected lesser trochanter that form a large, medially projected triangular crest ventral to the femoral head. The pes is distinguished from that of all other species of Protemnodon by: its taller, relatively narrower calcaneus with a less medially projected sustentaculum tali; and taller, more transversely compressed metatarsal V.
Protemnodon viator sp. nov. is most similar in aspects of cranial morphology to P. mamkurra sp. nov. It further differs from the cranium of P. mamkurra sp. nov. by its dorsoventrally shorter rostrum, lower medial ridge on the basioccipital, and more posteroventrally curved exoccipital over the foramen magnum. The dentary of P. viator sp. nov. cannot be differentiated from that of P. mamkurra sp. nov., and is otherwise morphologically closest to P. dawsonae sp. nov. and P. anak, from which it differs in having a taller mandibular corpus when fully grown. The dentition of P. viator sp. nov. cannot be differentiated from that of P. mamkurra sp. nov.
Protemnodon viator sp. nov. is most similar in aspects of postcranial skeletal morphology to P. dawsonae sp. nov. and P. mamkurra sp. nov. The axial skeleton of P. viator differs from both P. mamkurra sp. nov. and P. dawsonae sp. nov. in having more elongate caudal vertebrae. It is further separated from P. dawsonae sp. nov. by having a broader axis vertebra with a thicker spinous process, less laterally tilted postzygopophyses with more concave articular surfaces, and a bilobed, rather than rounded, ventral margin of the caudal extremity of the body. Additionally differs from P. mamkurra sp. nov. in having: an atlas vertebra with lateral vertebral foramina that open caudally, instead of laterally, and broader, more caudally projected wings; a more elongate axis vertebra, with a more caudally projected caudal extremity of the centrum; more elongate cervical vertebrae (C3–7), with a more horizontal, less roof-like arch, slightly larger pre- and postzygopophyses, and a more caudoventrally projected caudal extremity of the body with a slightly bilobed ventral margin; broader, straighter caudal transverse processes on caudal vertebra Ca7 and broader, straighter cranial processes on Ca8.
The forelimb of P. viator sp. nov. additionally differs from that of P. mamkurra sp. nov. in having: a humerus with the peak of the lateral supracondylar ridge less pointed and closer to the distal margin of the pectoral crest; a more gracile ulna; and a more elongate radius with a lower, less distinct caudal ridge and a less craniocaudally compressed distal shaft. The manus differs in having: a scaphoid with a broader palmar process, the facets for the hamatum and capitatum more distinct from each other, and the entire mesial section thickened instead of having a distinct, raised, transverse dorsal ridge for articulation with the styloid process of the radius; proximal phalanges with slightly less proximally projected palmar tubercles; and narrower, less dorsopalmarly compressed distal phalanges with larger, more palmarly projected palmar (flexor) tubercles.
The hindlimb of P.viator sp. nov. can be differentiated further from that of P. mamkurra sp. nov. in having: an ilium with a slightly broader lateral iliac spine and a shorter rectus tubercle; a femur with a more raised proximolateral ridge, narrower, deeper trochlea, narrower trochlear crests, the peak of the medial trochlear crest more pointed, and a less medially projected ventral section of the medial epicondyle; and a much more elongate tibia, which is longer relative to femoral length, with a thinner proximal section of the proximolateral crest, the cnemial crest less laterally curved with a more angular and distinct distal peak, and a straighter distal shaft in cranial view. The hindlimb of P. viator sp. nov. differs from that of P. dawsonae sp. nov. in having a pelvis with a more deeply concave gluteal fossa and acetabulum.
The pes of P. viator sp. nov. further differs from that of P. mamkurra sp. nov. and P. dawsonae sp. nov. in having: a calcaneus with a more triangular, less rounded calcaneal tuberosity in cross-section; shorter metatarsal IV; metatarsal V with a narrower, more dorsally situated facet for the cuboid; and a proximal pedal phalanx IV with a narrower waist. The pes further differs from P. dawsonae sp. nov. in having: a calcaneus with a deeper lateral talar facet and a narrower, more rotated medial talar facet; metatarsal V with a taller, less elongate proximolateral process and a less proximally projected medial plantar tubercle; and a proximal phalanx IV with a broader distal end relative to the proximal end. The pes additionally differs from P. mamkurra sp. nov. in having: a calcaneus with a smaller, more caudally displaced medial talar facet, less convex lateral talar facet, and a smaller, less dorsally bulbous fibular facet; a talus with a less cranially projected talar head and with its navicular facet aligned in the sagittal plane, rather than curving plantomedially; a taller, narrower cuboid with a longer, more plantarly projected lateral plantar tubercle, more plantarly projected medial plantar tubercle, and a deeper, narrower flexor groove; a narrower navicular with a more plantarly extensive ectocuneiform facet; ectocuneiform with a narrower, more plantarly extensive navicular facet and a deeper plantar tubercle that is squarer in medial view; relatively shorter, broader middle phalanx IV; distal phalanx IV having a more triangular dorsal peak and lacking distinct triangular divots on the medial and lateral margins of the proximal surface; and proximal phalanx V with a narrower waist.
Etymology:
Latin; nominative singular noun, meaning ‘traveller’ or ‘wayfarer’, in reference to the inferred greater vagility of this species compared to other species of Protemnodon.
Description and comparisons:
Cranium and dentition
Cranium (Figs 60 & 61): large and robust, with an elongate neurocranium. Rostrum. Rostrum moderately tall and elongate;; slightly ventrally deflected in juveniles, becomes more so with age. Diastema elongate, extends for roughly 70% of rostrum, and consists of slightly more maxilla than premaxilla. Premaxilla elongate, anteroventrally projected; ventral surface broad and flat, ventral width subequal to slightly less than the width across the nasal cavity; incisor-bearing component contributes ~50% of the ventral length from the anterior tip to the premaxilla-maxilla suture; anterodorsal margin slopes dorsoposteriorly (around the anterior margin of the nasal cavity) before curving steadily dorsally to the nasal suture; dorsoposterior part (‘walls’ of the nasal cavity) gently convex; ventral premaxilla-maxilla suture is angled distinctly posterolaterally, lateral premaxilla-maxilla suture extends straight dorsally before curving smoothly posteriorly toward the posterior of the nasal. The anterolateral surface of the anterior part of the premaxilla is pockmarked with very small foramina. Incisive foramen large and elongate, with a tapering channel extending anterolaterally from the foramen in ventral view, roughly toward I2; more posteriorly positioned relative to the incisors in mature individuals. Buccinator fossa large, smoothly concave, and quite deep, becoming shallower anteriorly; extends dorsally from ventral margin of diastema to midpoint of maxilla, and anteriorly from immediately anterior to P3/DP2 to between premaxilla-maxilla suture and base of I3. Infraorbital foramen large, narrow, opens anteriorly and positioned dorsal to P3/DP2. Nasal narrow, elongate and very slightly convex dorsally, forms slight concavity along mesial suture, with a linear lateral suture; projects anteriorly past the premaxilla and tapers to a mesial point. Frontal strongly concave at midpoint of temporal fossa, broadens toward anterior and flares over orbit; anterior suture with nasal and maxilla sinusoidal.
Lateral cranium. Temporal fossa elongate, with orbit slanted distinctly anteroventrally in lateral view (Fig. 60a). Lacrimal quite large and laterally projected, with small dorsoposterior foramen and larger anteroventral foramen, both with rounded tubercle situated immediately dorsoposteriorly, particularly large in some specimens. Masseteric process similar to that of P. mamkurra sp. nov.
Jugal dorsal surface flattened and slightly flared; curves dorsally posteriorly and bifurcates into a short, broad postorbital process and an elongate, narrow, ventrolaterally situated posterior part reaching almost to the glenoid fossa; posterolateral surface with low, angular ridge, merging anteriorly into laterally projected lip from ventral margin of orbit. The zygomatic arch is orientated dorsoposteriorly at 40–45° relative to axis of cheek tooth row. Zygomatic process of squamosal tilted slightly dorsally, posteriorly tall, smoothly convex laterally and with dorsal margin smoothly convex, particularly in older individuals; tapers anteriorly to elongate point between the postorbital process and the posterior part of the jugal.
Palatal region. Maxilla ventrally broad, and flat to very gently concave. Maxillary foramen quite large, round and opens posteriorly, with a broad, rounded valley extending posteriorly from the opening; sphenopalatine foramen round and slightly smaller. Palatine thick, broad and lacking fenestrae, with a narrow, elongate anterolateral foramen level with the anterior of M3, and a small, rounded posterolateral foramen adjacent to the posterior of M4; lateral margin tapers gently anteriorly before forming a linear transverse maxilla-palatine suture level with the abutment of M2–M3; posterior margin concave to slightly V-shaped, situated posterior to M4. Pterygoid crest thin and elongate, with the anterior peak tall and slightly posteriorly deflected. Pterygoid (anteromedial) wing of the alisphenoid relatively low and thick, abuts the pterygoid crest laterally, flares posterolaterally and lowers to merge into the body of the alisphenoid.
Dorsal and posterior cranium. Parietals broad and smoothly convex. Supraoccipital broad and quite tall, smoothly curves posteriorly toward the foramen magnum, such that the exoccipital projects beyond the posterior margin of the parietal and the supraoccipital is slightly concave; dorsolateral margin is rounded and dorsal margin is flattened; a very low, broad medial ridge is occasionally present; supraoccipital is low in juveniles, height increases relative to width with age though height typically does not exceed occipital width. Foramen magnum broad, oval and slightly to moderately dorsoventrally compressed. Occipital condyles large and quite tall; situated lateral to and angled obliquely beneath the foramen magnum, not extending dorsally beyond the dorsal margin of the foramen magnum (Fig. 61b); taper ventromedially in posterior view and project posteriorly well beyond the margin of the occipitals in lateral view; in young individuals, the dorsolateral margin of each condyle is ventral to a rounded and variably shallow foramen on the exoccipital, becoming obscured by larger, more elongate condyles in older individuals.
Neurocranial region. Temporal crest morphology and ossification are as in P. anak. Basioccipital broad and smoothly convex, with a low medial ridge that becomes more raised and angular with age (Fig. 61a); condyloid foramen is rounded, partially to completely covered by the anteroventral margin of the occipital condyles in ventral view. Medial pterygoid origin thin and tall; curves anteromedially to continue anteriorly into the pterygoid crest. Pterygoid fossa very deep and elongate, bordered by a low, narrow, rounded anteroposterior ridge extending from the base of the pterygoid wing of the alisphenoid to abut the medial margin of the foramen ovale.Anterolateral surface of the body of the alisphenoid is broad, and flat to gently convex; extends from the foramen ovale to the petrotympanic fissure, with a very small, rugose eminence abutting the medial margin of the anterior process of the ectotympanic. Glenoid fossa broad, flat and abutting the postglenoid process posteriorly. Postglenoid process moderately well-developed, tapering to a pointed or squared ventral margin; angled anterolaterally in ventral view, with the posteromedial component extending ventrally into, and semi-fused with, the anterior process of the ectotympanic, forming a deep, anterior-facing ventral postglenoid foramen. Ectotympanic has a large, rugose anterior process projected ventral to and medial to the postglenoid process. External auditory meatus roughly cylindrical, angled dorsolaterally; not projected laterally beyond the margin of the anterior process of the ectotympanic.
The cranium of P. viator sp. nov. differs from all compared taxa in possessing a more anteroventrally slanted orbit; from P. anak in being relatively broader, with a slightly shorter diastema relative to cranial length, generally broader, slightly more curved, more ventrally situated occipital condyles, and in lacking a thin anterior jugal ridge; from P. mamkurra sp. nov. in having a dorsoventrally shorter rostrum, taller, straighter, generally more dorsally situated occipital condyles, a more posteroventrally curved exoccipital, and a lower, more rounded medial ridge on the basioccipital; from C. kitcheneri in being larger, relatively broader and more robust, lacking a bony nasal cavity ‘pocket’, and having a less domed, less anteriorly projecting nasal, a taller, more robust anterior part of the premaxilla, larger masseteric process, a much thicker and less laterally projected ventral orbital rim, taller zygomatic arch, more posteriorly projected occipital condyles, a single anteroposterior ridge meeting the medial margin of the foramen ovale, and the anterior process of the ectotympanic extending to the ventral or ventromedial tip of the postglenoid process (rather than wrapping around posterior surface); and from W. bicolor in being much larger, lacking a small, pointed, anteriorly projected eminence on the anterior margin of the jugal, and having a more ventrally projected anterior part of the premaxilla, larger masseteric process, more robust palatine lacking fenestra, more posteriorly projected occipital condyles, more raised anteroposterior ridge meeting the medial margin of the foramen ovale, relatively larger, more laterally extensive anterior process of the ectotympanic, and a taller, more laterally projected postglenoid process.
Upper dentition (Fig. 62): I1: broad, robust and arcuate, with thick buccal enamel extending around to the edges of the lingual surface; buccal surface smooth and gently convex, with a very shallow vertical groove in juveniles; occlusal surface oval; with wear, the enamel recedes from the lingual surface and the occlusal surface narrows and deepens, occasionally develops a distinct angle between the top of the buccal enamel and the dentine (Fig. 62b). I2: small and narrow, with gently convex buccal enamel extending onto the lingual margins; posterolingual crest small, with an associated mesial groove on the buccal enamel, lost when tooth is slightly worn; enamel recedes from the lingual surface and the occlusal surface shortens and broadens with wear. I3: elongate, transversely compressed and trapezoidal to roughly triangular in buccal view; buccal enamel convex, buccal length less than the width of I1 (Fig. 62a). Main curves anterolingually to sit lingual to the posterior margin of the similarly shaped anterobuccal crest. Anterobuccal crest is around half the length of the main crest.
The cheek teeth are high-crowned. DP2: morphologically very similar to P3 but anteroposteriorly truncated; quite short, broad and oblong, broadens posteriorly, with thickened peaks over the anterior and posterior roots linked by the high main crest. Main crest blade-like, anteroposteriorly to slightly posterobuccally orientated, and jagged to gently undulating in lateral view, with a very low, dorsoventrally aligned ridgelet on the midpoint of the buccal face. Lingual crest low and gently undulating in lingual view, extends from the lingual base of the anterior cusp to the small, secondary posterolingual peak; lingually borders a broad, anteriorly tapering lingual basin, perpendicularly transected by a low ridgelet anterior to the midpoint. A small posterior basin with moderately high anterior and posterior margins sits at the posterior margin of the DP2, between the posterior and posterolingual peaks, removed by a small amount of wear. DP3: molariform, short and broad, with the protoloph and metaloph markedly narrower than the swollen loph bases; anterior loph longer and narrower than the posterior loph. Precingulum small, narrower than the anterior loph, merges buccally with the thin, low but distinct preparacrista. Postparacrista thin and distinct, extends straight from the paracone to the buccal margin of the interloph valley. Postprotocrista and postmetaconulecrista curve gently toward the midline of the tooth; in some specimens, postprotocrista extends onto anterior face of metaloph as a low but distinct crest.
P3: large, elongate and oblong, tapers to a small, blunted cusp at the anterior base; generally slightly broader posteriorly, with posterior margin rounded; in occlusal view, P3 varies from straight to slightly buccally curved toward the posterior, with the posterior component very slightly rotated buccally, contributing to the occasional slightly crescentic shape of the tooth. Thickened peaks over the anterior and posterior roots are linked by the tall main crest. Main crest high, blade-like and roughly anteroposteriorly orientated with occasional very slight posterobuccal curvature in occlusal view, slightly jagged to gently undulating in lateral view with two or three low to very low, dorsoventrally aligned ridgelets on the midpoint of the buccal face. Anterior cusp generally slightly narrower than the posterior, with the peak tall and coming to a rounded point; peak intersected by very brief transverse crest. Lingual crest moderately high, extends from the lingual base of the anterior cusp to merge into the posterolingual peak, with two or three gentle, rounded peaks. Lingual crest borders broad lingual basin, which is perpendicularly transected by one to three very low, indistinct ridgelets. Main posterior peak quite tall and rounded, continuous with the main crest, which extends and broadens posteriorly to merge with a low, narrow transverse posterior crest. Posterolingual peak rounded, lower than the main peak and linked to the main crest by a thin transverse crest, anteriorly bordering the posterior basin. A small posterior basin sits between the main and posterolingual peaks, posteriorly bordered by the transverse posterior crest, removed by a small amount of wear.
Molars: rounded-rectangular; interloph valley generally slightly narrower than the lophs; occasionally the M1, and more rarely M2, are rounded, with a broad interloph valley. Lingual and buccal margins of the lophs slightly to moderately convex in posterior view,particularly the anterior lophs, with the protoloph and metaloph narrower than the corresponding loph base; unworn protolophs and metalophs are gently concave posteriorly in occlusal view. Precingulum variably broad, narrower than the anterior loph, extends from the anterobuccal margin to adjacent to the anterolingual margin, gently medially tilted; flat, broad and shelf-like when worn; generally becoming slightly larger, broader and more projected toward M4; some specimens with small enamel crenulations on occlusal surface; preprotocrista absent or very slight. Preparacrista usually absent, sometimes present but very low and indistinct. Postparacrista thin and low but distinct; initially straight before curving lingually to be adjacent to or merging with the buccal component of the postprotocrista in the interloph valley. Postprotocrista relatively thicker, straighter and more raised, extends from the protocone to around the midpoint of the interloph valley; in most specimens, the postprotocrista extends to or near to the metaconule as a low, thin crest.A very small, rounded cusp is variably present (on one or more molars, sometimes on only one side of the dentition) on the base of the protoloph on the buccal margin of the interloph valley (Fig. 62d), and/or on the base of the metaloph in the interloph valley abutting the lingual margin (see SAMA P53836), with either or both cusps occasionally present in DP3. Premetacrista very slight, extends from the metacone to meet the base of the postparacrista in the interloph valley Postmetaconulecrista quite thick and raised, arises from the metaconule and curves dorsobuccally to form an oblique shelf beneath the posterior basin. Postmetacrista lower, shorter and less distinct; arises from the metacone and deflects lingually to merge into the buccal margin of the posterior basin.
The upper dentition of P. viator sp. nov. differs from that of P. anak in being generally larger, with a broader I1 relative to the length of I3, a relatively broader DP2–3, a DP3 with a very slight to absent preprotocrista and a complete protoloph, a more robust and relatively broader P3 across the anterior cusp with lower, less distinct transverse ridgelets on the main crest and a higher, less jagged and relatively more elongate (more anteriorly extensive) lingual crest, and generally relatively broader molars with lower, less distinct preparacrista; from P. mamkurra sp. nov. in being generally larger, with P3 with a slightly broader anterior relative to length and relatively narrower anterior loph of M1; from P. tumbuna in being larger and higher crowned, with the molars generally less rounded in occlusal view, precingulum more anteriorly projected, and the postprotocrista higher and more distinct; from P. dawsonae sp. nov. in being larger, with a broader I1 relative to I3, relatively slightly narrower posterior molars, and molars with a less distinct and gently curved (rather than kinked) postparacrista; from P. otibandus in being larger and higher crowned, with broader I1, less raised and less distinct transverse ridgelets on P3, relatively broader DP2 and 3, DP2 with fewer and lower transverse ridgelets, and molars always lacking a urocrista and having the postprotocrista, postmetacrista and postmetaconulecrista higher and more distinct; from P. snewini in being much larger and higher crowned, with P3 relatively broader, and molars relatively narrower, with higher and more distinct postprotocrista, postmetacrista and postmetaconulecrista; from C. kitcheneri in being much larger and higher crowned, with P3 broader anteriorly, longer relative to the molars and with a higher, relatively longer lingual crest, and molars with a higher postprotocrista; and from W. bicolor in being much larger and higher crowned, with a relatively broader I1, P3 with a higher lingual crest and a larger posterior basin, and molars with a thicker postprotocrista distinctly extending to the protocone, rather than merging into the centre of the posterior surface of the protoloph.
Dentary (Fig. 63a–f): robust, tall and transversely compressed, with a moderately elongate and gently tapering diastema projected straight or slightly deflected dorsally. Mandibular symphyseal plate elongate, extends along the entirety of the diastema to abut the posterior margin of i1. Mental foramen round to oval, opens laterally to anterolaterally, located roughly one-quarter of the distance from dp2/p3 to i1 and between one-quarter and one-third of the distance from the dorsal margin of the diastema to the ventral margin. Depth of the mandibular corpus decreases slightly from below p3 to m4. Digastric sulcus broad, varies from shallow to very shallow, extends from beneath the posterior of the molar row toward the anteroventral margin of the medial pterygoid fossa. Buccinator sulcus distinct but quite shallow, extends along the buccal surface of the mandibular corpus with a slight ventral tilt posteriorly, slightly ventral to the three–four anteriormost cheek teeth.
Ascending ramus tall and slightly convex medially. Coronoid crest angled 70–90° from the plane of the tooth row; straight to slightly convex; coronoid process becomes anteroposteriorly shorter dorsally and curves to a rounded, posteriorly projected crest; crest smaller and more pointed in juveniles. Masseteric fossa tall, shallow, broadly U-shaped in lateral view; bounded anteriorly and ventrally by a low ridge; posterior part is shallower than the anterior component, with a posterolateral lip from the laterally projected ‘shoulder’ present on the base of the condylar process. Masseteric foramen deep, oval, elongate and transversely compressed; situated in the anteroventral part of the masseteric fossa, abutting the anterior margin and sharing the anterior part of the lateral lip. Masseteric dental canal very deep, separated from the mandibular foramen and the inferior dental canal by a narrow dorsal crest running anteroposteriorly. Medial pterygoid fossa large, broad and very deeply concave, broadened and deepened by the tall, medially projected angular process. Mandibular foramen moderately sized, round to oval, and transversely compressed. Angular process present as a thin anteroposterior crest, extends dorsoposteriorly along the posterior component of medial margin of medial pterygoid fossa, unprojected posteriorly. Posteroventral margin of dentary rounded and smoothly convex in lateral view, straightens dorsally to meet the posteroventral margin of the mandibular condyle. Condylar process tall, not posteriorly projected; occasional very slight dorsal projection. Mandibular condyle flat and smooth, oval with a small indent in the posterior margin, slightly anteroposteriorly compressed and tilted medially and slightly anteriorly.
The dentary of P. viator sp. nov. cannot be differentiated from that of P. mamkurra sp. nov. It differs from that of P. anak in being generally larger, broader and more robust, with a shorter, more dorsally deflected diastema relative to tooth row length; from P. tumbuna in being larger, with a more anterodorsally situated mental foramen and a straighter, slightly more posteriorly deflected coronoid crest; from P. dawsonae in being generally larger; from P. otibandus in being larger and more robust, with a more robust diastema, taller mandibular corpus, shallower posterior part of the masseteric fossa, and a less anteriorly tilted mandibular condyle; from P. snewini in being larger and more robust, with a much taller mandibular corpus, particularly posteriorly, a less elongate and taller diastema relative to the mandibular corpus, and a squarer, less posteriorly projected angular process; from C. kitcheneri in being larger and more robust, with a relatively shorter, more dorsally deflected diastema, more posteroventrally situated mental foramen, taller mandibular corpus, deeper buccinator sulcus, anteroposteriorly longer coronoid process, deeper medial pterygoid fossa with a higher posterior margin, larger dorsal septum partially separating the masseteric and mandibular foramina, and a relatively dorsally situated masseteric fossa; and from W. bicolor in being much larger, with a more dorsally deflected diastema, a deeper buccinator sulcus, a broader, more oval mandibular condyle, and a larger dorsal septum partially separating masseteric and mandibular foramina.
Lower dentition (Fig. 63d–g): i1: procumbent, broad and robust; acuminate and ventrobuccally-dorsolingually compressed when unworn, cross-section becomes shorter and rounder with wear. Thick enamel completely covers the buccal surface. Dorsobuccal margin has a thin, raised enamel crest. The enamel is thick and rounded around the ventrolingual margin and covers the ventral half of the lingual surface when unworn, with the lingual enamel layer tapering posteriorly such that well-worn i1s lack lingual enamel.
The cheek teeth are high-crowned. Tooth rows are roughly straight and parallel in occlusal view, occasionally very slightly convex in juveniles; in lateral view, tooth row is sloped slightly ventrally toward the posterior; the proportional rate of wear along the tooth row is highly variable as a result of the variability of the tooth row angle. dp2: morphologically very similar to p3 but anteroposteriorly about half as long; blade-like, tall and triangular in cross-section, roughly oblong to mucronate in occlusal view, broadens gently to the posterior. Main crest thin, gently undulating, aligned anteroposteriorly, extends from over the anterior root to over the posterior root and twists lingually to the posterolingual extremity; buccal and lingual surfaces have a very low, indistinct ridgelet or undulations aligned dorsoventrally. Anterior cuspid semi-distinct from the main crest, being slightly broader with slightly raised posterior margins. dp3: molariform, very similar to the morphology of m1 but relatively narrow; both the lophids crests are significantly narrower than the bases, and are slightly convex posteriorly in occlusal view when unworn to moderately worn; lophid bases bulge slightly buccally. Precingulid fairly small, variably narrow, width tapers anteriorly. Paracristid thin, encircles the base of the premetacristid and curves around the anterior margin of the precingulid, creating a distinct, deep trigonid basin, then turns posteriorly, climbs rapidly and twists buccally to the protoconid; when worn, it extends posteriorly as a low ridge and curves buccally to the protoconid. Premetacristid low and thin, climbs posterolingually from the trigonid basin with a slight buccal curve to the metaconid; removed by a small amount of wear. Postprotocristid very slight to absent, anteroposteriorly aligned, merges with the cristid obliqua in the interlophid valley. Cristid obliqua slightly buccally displaced, thin and moderately high when unworn; mostly part of the trigonid, with a low talonid contribution extending to the hypoconid. Preentocristid low and broad, extends lingually from adjacent to the cristid obliqua to the entoconid. Postcingulid small, shelf-like to slight and lipped, slightly narrower than the posterior of the talonid base.
p3: blade-like, tall and triangular in cross-section with ‘bulging’ buccal and lingual bases, elongate and oblong in occlusal view; typically with a slight waist, occasionally with parallel or posteriorly diverging margins or a slight bulge around the centre; typically broader across the posterior root than the anterior root. Anterior cuspid has its posterior margins marked by posterior facing ridgelets that occasionally extend dorsally to form a short transverse crest that intersects main crest; anterior cuspid occasionally has a slight anterior eminence at its base. Main crest linear, anteroposteriorly aligned, twists distinctly lingually over the posterior root; lingual and buccal surfaces with one to three low, rounded, indistinct, roughly dorsoventrally aligned ridgelets on crest, such that unworn and slightly worn crest appears slightly jagged in buccal view.
Molars: rounded-rectangular in occlusal view, with the interlophid valley slightly broader to narrower than the lophid bases; when unworn or slightly worn, the protolophid and hypolophid are posteriorly convex or have a mesial kink toward the posterior in occlusal view; lingual component of the hypolophid is slightly posteriorly tilted, becoming straight and perpendicular to the tooth row centreline with moderate wear; buccal margins of the lophids slightly more convex than the lingual margins in posterior view. Precingulid fairly large, typically comes to a rounded point but is sometimes rounded. Paracristid thick and raised; lingual component anterolingually projected, bounds anterobuccal margin of trigonid basin then ascends posteriorly and curves gently buccally to the protoconid; the degree of buccal curve increases with molar wear. When unworn, the protoconid is higher than the metaconid; ‘folding’ of protoconid enamel is as in P. anak and P. mamkurra sp. nov. Cristid obliqua thick and quite low, mostly part of the talonid, arises from the midpoint or slightly buccal to the midpoint of the interlophid valley, curves very slightly buccally and extends to the hypoconid. Preentocristid very low, broad and indistinct, arises midway between the base of the cristid obliqua and the lingual extremity of the interlophid valley and deflects slightly lingually to meet the entoconid. When little worn, the hypoconid is distinctly taller than the entoconid and slightly lingually displaced. Postcingulid narrow and slight on m1–m2, becomes broader and shelf-like in m3 and particularly in m4.
The lower dentition of P. viator sp. nov. differs from that of all other species of Protemnodon except P. mamkurra sp. nov. in having a broader posterior of the p3 relative to length. It further differs from P. anak in having broader i1 with less raised dorsobuccal crest and lacking ventrolingual crest, dp2 slightly broader, p3 with fewer, less raised and less distinct ridgelets on main crest, and larger, generally relatively broader molars with a smaller precingulid and more convex buccal lophid margins; from P. mamkurra sp. nov. in being generally larger; from P. tumbuna in being larger and higher crowned, with relatively larger, broader i1 lacking a ventrolingual crest, relatively broader p3, and m3–4 with less convex buccal lophid margins and a less raised premetacristid; from P. dawsonae sp. nov. in being generally larger and higher crowned, with i1 lacking a low, thick ventrolingual crest; from P. otibandus in being larger and higher crowned, with relatively larger, broader i1 lacking a ventrolingual crest, relatively broader p3 and m3–4 with less convex buccal lophid margins; from P. snewini in being larger and higher crowned, with relatively larger, broader and more dorsally deflected i1 lacking a ventrolingual crest and having enamel more extensive across the ventral component of the lingual surface, p3 with fewer, less distinct ridgelets on the main crest, and molars with a smaller precingulid and larger premetacristid; from C. kitcheneri in being larger and higher crowned, with broader, more spatulate i1 lacking a ventrolingual crest, relatively broader dp2 and 3, larger and absolutely more elongate p3 that is longer relative to molar lengths, and molars with narrower lophid crests, a stronger premetacristid, higher cristid obliqua, and a postcingulid present; and from W. bicolor in being much larger, with a broader, more spatulate i1 lacking a ventrolingual crest, p3 with less raised, less distinct ridgelets on the main crest, and molars with narrower lophid crests, generally more anteriorly projected precingulid, and a thicker, lower cristid obliqua.
Axial skeleton
Atlas (C1) (Fig. 64a–d): large, broad and quite robust. Arch thick and deep, with a raised, rugose, cranially situated dorsal tubercle. Cranial articular surfaces very broad, deeply concave, particularly in dorsoventral plane, and angled strongly medially; ventromedial components narrow to rounded points. Ventromedial processes elongate, rounded in ventral view, and close medially but not touching. Caudal articular surfaces rounded, gently concave, and very slightly extending down the ventromedial processes. Wings large, broad, and flaring from a craniocaudally deep base; extend caudally to or beyond caudal extent of caudal articular surfaces (Fig. 64c). Lateral vertebral foramina large, quite broad, craniocaudally shallow and opening dorsocaudally (Fig. 64d); extend from immediately cranial to base of wings onto dorsolateral surface of arch.
The atlas vertebra of P. viator sp. nov. differs from that of P. anak in having a slightly less deep arch and more rounded caudal articular surfaces; from P. mamkurra sp. nov. in having lateral vertebral foramina that open caudally instead of laterally, with broader, caudally projected wings; from C. kitcheneri in being larger and relatively broader, with a deeper arch, larger dorsal tubercle, lateral vertebral foramina opening caudally, and less caudally projected caudal articular surfaces, and lacking a broad groove that extends ventrally from the lateral ventral foramina; from O. rufus in being larger, with a deeper arch, dorsal tubercle present and broader and more caudally deflected wings; from M. fuliginosus in being larger, with a dorsal tubercle present, and broader, more caudally deflected wings; and from W. bicolor in being larger, relatively slightly taller and more solidly built, with a rounder, less pointed dens, rounded and slightly taller cranial articular surfaces, a less convex dorsal margin of the spinous process, and a broader caudal extremity of the centrum.
Axis (C2) (Fig. 64e–h): moderately craniocaudally short, quite broad and robust. Dens elongate and gently dorsally deflected.Cranial articular surfaces broad, tall and gently convex; angled laterally and very slightly dorsally. Arch quite thick, tall and roof-like.Vertebral canal rounded to domed. Spinous process tall, very elongate and tilted strongly cranially, with the dorsal margin linear (Fig. 64e); cranial component thickened, rugose and projected slightly beyond cranial margin of arch, narrows caudally before thickening to very elongate, projected caudal extremity, extending caudally beyond margin of postzygopophyses and caudal extremity of the centrum. Postzygopophyses quite small, caudally projected and flared laterally; articular surfaces concave and face ventrally, with a very slight caudal and lateral tilt. Transverse processes abraded; bases preserved interpreted as suggesting quite short and thin morphology. Ventral surface of the centrum broad and rugose, with low, elongate, rugose tubercle on mesial midline of cranial component and broad, shallow fossae either side of the base of the caudal extremity of the centrum. Caudal extremity of the centrum very slightly caudally projected, gently dorsoventrally compressed and slightly dorsally tilted, with gently bilobed ventral margin (Fig. 64h) projecting very slightly caudally.
The axis of P. viator sp. nov. differs from that of P. anak in being much less elongate, with more convex and dorsolaterally tilted cranial articular surfaces, a shorter and more dorsally deflected dens, smaller, more rounded postzygopophyses, a more caudally projected spinous process with a more cranially tilted dorsal margin and a less elongate base, and a much less caudally projected caudal extremity of the centrum; from P. mamkurra sp. nov. in being longer relative to width, with caudal extremity of the centrum more caudally projected; from P. dawsonae sp. nov. in being larger and broader, with a broader spinous process, less laterally tilted postzygopophyses with more concave articular surfaces, and a bilobed, rather than rounded, ventral margin of the caudal extremity of the centrum; from C. kitcheneri in being larger, and broader relative to depth, with a broader, more cranially slanted and more caudally extensive spinous process, and a relatively larger, broader and less caudally projected caudal extremity of the centrum with a bilobed ventral margin; from O. rufus and M. fuliginosus in being larger, and in having a thicker spinous process with a cranially slanted dorsal margin and thickened, caudally projected caudal tip, and caudal extremity of the centrum with bilobed ventral margin; and from W. bicolor in being larger, with a deeper arch, larger dorsal tubercle, more caudally deflected wings and less caudally projected caudal articular surfaces.
Cervical vertebrae (C3–C7) (Fig. 65a): quite short and broad; the articulated neck exhibits distinct dorsal curvature through C4–7, centred around C6. Cranial extremity of the centrum broad and concave, particularly at the lateral margins, with slight ventral tilt. Prezygopophyses moderately well-developed and broad, not extending cranially past cranial extremity; articular surfaces dorsal facing and slightly craniomedially tilted; no ridge separates articular surface from dorsal surface of arch. Vertebral canal not known. Arch broad and approaching horizontal. Spinous process mostly abraded; bases narrow, becoming shallower and broader towards C7. The ventral surface of is centrum gently convex. Transverse processes poorly developed in juveniles, becoming relatively broad and thickened with age; quite thickened, broad and caudally deflected, most caudally deflected in C3, broadest in C4, becoming decreasingly caudally deflected and increasingly thicker and narrower towards C7; tubercle on ventral base of transverse processes very low, narrow and slightly elongate in C5, distinctly more elongate craniocaudally, thickened and ventrally projected in C6, and shorter, broader, slightly cranially deflected and more cranially situated in C7. Postzygopophyses moderately well-developed and broad, extending marginally beyond caudal extremity of the centrum; articular surfaces slightly to moderately laterally tilted. Caudal extremity of the centrum broad and slightly caudoventrally projected, with a slightly bilobed ventral margin.
The cervical vertebrae of P. viator sp. nov. differ from those of from P. anak in being lower, broader and less deep, with smaller pre- and postzygopophyses, lower, broader cranial extremity of the centrum and lower, broader, less caudoventrally projected caudal extremity of the centrum with a slightly bilobed ventral margin; from P. mamkurra sp. nov. in being deeper, with more horizontal, less roof-like arch, slightly larger pre- and postzygopophyses and more caudoventrally projected caudal extremity of the centrum with a slightly bilobed ventral margin; from P. tumbuna in being larger and slightly more elongate, with more robust transverse processes; from C. kitcheneri in being less elongate, with a less caudally projected caudal extremity of the centrum; from O. rufus in having more robust transverse processes and less cranially projected arches; and from M. fuliginosus and W. bicolor in being larger, with smaller, less cranially projected ventral tubercles of the transverse processes on C3–5 and smaller, less elongate ventral transverse tubercles on C6 and 7.
Thoracic vertebrae (T1–T14) (Fig. 65a): only preserved in situ in articulated specimens paratype SAMA P53835 and holotype SAMA P59552. Thoracic vertebrae total 14; vertebrae craniocaudally short relative to width. Rib length increases rapidly to maximum at ribs 6 and 7 (rib 7 length = ~ 215 mm), decreases steadily to rib 14. T1–3: entirely obscured by scapulae in both available specimens, which also obscure all but tip of spinous process of T4 and obscure majority of T5 and 6; heads of ribs hide area ventral to pedicles in T7–13; all vertebrae tightly articulated, obscuring view of cranial and caudal extremities of the centra. Spinous process long, slightly caudally curved and strongly caudally deflected in T4–8, with that of T4 most transversely compressed; in T5 and 6 relatively thick and robust; in T7 and 8 increasing in depth and transverse compression; in T9 quite deep and lacking caudal deflection; in T10–14 undeflected, with thickened tips and increasingly short and deep. Pre- and postzygopophyses mostly abraded or obscured in T1–10, appear quite small, undeflected laterally or dorsally, situated on arch, with position beginning to migrate slightly dorsally from T9; in T11 relatively larger, with postzygopophyses situated on caudolateral base of the spinous process;T12is a transitional vertebra,with smaller, dorsal facing, cranially projected prezygopophyses and robust, ventrolateral facing, dorsolaterally projected postzygopophyses; T13 and 14 with very large, deep, transversely compressed, dorsomedial facing, dorsolaterally projected prezygopophyses and quite short, robust and ventrolateral facing postzygopophyses. Diapophyses short but quite deep and robust; gently dorsally deflected in T7–10; become shorter, more robust and less dorsally deflected in T11–14 (extend dorsally above cranial articular surfaces in T12 only). Caudal accessory processes ancillary to postzygopophyses; present on T13 as small triangular eminences on caudal surface of the base of diapophyses; in T14 elongate, lobe-shaped processes extending from caudal surface between arch and diapophysis to articulate with lateral surface of prezygopophyses of L1.
The thoracic vertebrae of P. viator sp. nov. cannot be differentiated from those of P. mamkurra sp. nov. They differ from P. anak in having generally relatively larger, more robust diapophyses; from C. kitcheneri in being larger with relatively larger, more robust diapophyses and possibly, based on comparison of the articulated thoracolumbar column, lesser thoracic lordosis (ventral curvature) and thoracolumbar kyphosis (dorsal curvature); from O. rufus, M. fuliginosus, and W. bicolor, in numbering 14, with the transitional vertebra situated at T12 rather than T11; further from O. rufus in having the spinous processes of T5–8 relatively shorter and more caudally curved, and the diapophyses of T6–8 slightly more cranially deflected; further from M. fuliginosus in having relatively shorter spinous processes on T5–8; and further from W. bicolor in being much larger, with less dorsally deflected diapophyses in T7–10 and relatively taller spinous processes on T10–13.
Lumbar vertebrae (L1–5) (Fig. 65a): lumbar vertebrae total five; vertebrae quite large and robust; in most complete available specimen, ventral component of L1–3 partially obscured or abraded and dorsal components of L4 and 5 abraded; vertebral canals, caudal extremities of the centra, and cranial and caudal articular surfaces not visible due to articulation. Centrum length slightly greater than width; gently increase in size and length toward L5; ventral and lateral surfaces bowed strongly inwards, creating a distinct waist at the midpoint. Cranial extremities of the centrum not visible in L1, 2 and 5 and abraded in L3; large and rounded in L4. Prezygopophyses large, projected cranially well beyond the margin of the centrum and angled craniodorsally from the base before curving dorsally toward the tip; cranial articular surfaces interpreted as strongly medially tilted. Spinous processes quite tall and robust, very deep and transversely compressed in L1–2; slightly cranially deflected in L1; undeflected in L2; abraded in L3–5. Postzygopophyses quite small, rounded and gently laterally deflected. Caudal accessory processes present on L1 and 2 as lobe-shaped, dorsocaudallyprojectedprocessesarisingonlateralsurface of arch, cranioventral to bases of postzygopophyses; abraded in L3–5. Transverse processes mostly obscured on L1, arise on lateral surface of the centrum immediately caudal to cranial margin; on L2 arise on lateral surface of the centrum midway between cranial margin and midpoint, dorsoventrally planar and projected ventrolaterally before curving strongly cranially; become slightly deeper and situated more dorsally in L3–5.
The lumbar vertebrae of P. viator sp. nov. cannot be differentiated from those of P. mamkurra sp. nov. They differ from those of P.dawsonae sp. nov. in being generally larger, with less deep transverse processes, centrum with relatively taller, narrower cranial and caudal extremities, less deeply concave ventrolateral surfaces, and a less deeply concave ventral margin in lateral view; from C. kitcheneri in being larger, with a relatively slightly longer centrum; from O. rufus and M. fuliginosus in numbering five, with a deeper, more robust spinous process; and from W. bicolor in being much larger and in numbering five.
Caudal vertebrae (Ca1–13, 18–20) (Fig. 65b): numerical position of distal vertebrae not certain; large and moderately robust. Prezygopophyses: in Ca1–4, large, flattened, flared and rounded across distal margins with articular surfaces angled dorsomedially and projected craniomedially, becoming deeper and more flared toward Ca5; Ca6 has tall, less laterally projected non-articular mammillary processes (prezygopophyses); Ca7 onwards have increasingly smaller, blunter and thicker mammillary processes lacking articular surfaces. Postzygopophyses:in Ca1–4,relatively taller and narrower than prezygopophyses, with small, rounded articular surfaces; Ca7 and distal vertebrae have increasingly reduced postzygopophyses that migrate caudally to abut the caudal margin as low, thin, parallel ridges in the distal vertebrae. Centra: Ca1–5, craniocaudally short with slightly ventrally inclined cranial and caudal extremities; Ca6 onward, centra become straighter and more elongate, before decreasing in size and length around Ca10; Ca12– 14, increasingly short, robust centra that narrow to a strong waist; Ca18–20 very short and robust; cranial and caudal extremities of the centrum remain rounded with slight dorsoventral compression throughout the caudal vertebrae.Vertebral canal:low and broad in Ca1,becoming increasingly low toward Ca4, extremely small in Ca6–9 and absent in distal vertebrae. Transverse processes: poorly preserved in the available proximal vertebrae; Ca1, flattened and deep; Ca2, very deep and broad; Ca3 and 4, broader, shorter, more caudally situated and more caudally deflected; large and flattened in Ca5; Ca6 lacks cranial transverse processes and Ca7 has extremely small, thin cranial transverse processes, Ca6 and 7 have short, broad caudal transverse processes adjacent to the caudal margin with curved cranial margins extending cranially as thin ridges, processes less curved and broader in Ca7; distal vertebrae possess small, blunt, dorsoventrally compressed and ventrally deflected cranial and caudal transverse processes linked by a thin, low ridge that lowers to minimum around the midpoint of the centrum, with the cranial processes relatively larger than the caudal; cranial and caudal transverse processes slightly cranially and caudally deflected respectively. Spinous process: increasingly small and rounded in Ca1–4; very reduced or absent in Ca5 onward. Cranioventral processes: small, blunt, ventrally projected on Ca6, positioned close to the midline and curving gently mesially toward the tip; become larger, thicker, more mesially curved, and more elongate relative to vertebra distally.
The caudal vertebrae of P. viator sp. nov. differ from those of P. anak in being generally more elongate, with the caudal transverse processes of Ca7 shorter and slightly broader; from P. mamkurra sp. nov. in being more elongate and in having broader, straighter caudal transverse processes on Ca7 and cranial processes on Ca8; from P. tumbuna and P. dawsonae sp. nov. in being larger and more elongate; from C. kitcheneri in being larger, with broader, more laterally flared prezygopophyses in Ca2–4, broader caudal transverse processes on Ca7, and more elongate distal caudal vertebrae; from O. rufus in having broader, more laterally flared prezygopophyses in Ca1–5, broader caudal transverse processes on Ca7, and in having Ca7 (rather than Ca6) as the first vertebra to bear cranial transverse processes; from M. fuliginosus in being larger and more robust, with the prezygopophyses of the proximal caudal vertebrae more rounded around the distal margins, subequally broad cranial and caudal extremities of the centra of Ca4–6 (rather than cranial extremity being narrower), and in having Ca7 (rather than Ca6) as the first vertebra to bear cranial transverse processes; and from W. bicolor in being much larger and more elongate, with larger caudal transverse processes on Ca7–11.
Pectoral girdle and forelimb
Scapula (Fig. 66a–c): large, slightly broader than depth. Acromion well-developed, thickened and lobed in dorsal view, deepens to a rounded lateral end, projects laterally beyond margin of the supraglenoid tubercle. Spine cranially inclined in lateral view; lateral component tall and thickened, becomes lower medially to merge with the scapular body well short of the cranial angle (Fig. 66a). Scapular notch moderately deep and obtuse, around 110°. The cranial border is thickened. Cranial angle thickened, rounded and obtuse.The medial border between the cranial and caudal angles is not preserved. Caudal angle roughly right-angled. Caudal border linear to very slightly convex with a slight caudal eminence close to the caudal angle; distinctly thickened relative to the infraspinous fossa and other borders, becoming thicker, rounded and swollen laterally. Supraspinous fossa very gently concave, roughly half the size of the infraspinous fossa. Infraspinous fossa large and gently convex. Subscapular fossa slightly concave, with a very slight convexity bounding a slight, shallow mesial channel that extends transversely, ventral to the scapular spine. Glenoid cavity large, concave, oval and transversely compressed, with the cranial component gently projected laterally. Supraglenoid tubercle thin, blunt and slightly projected laterally. Coracoid process blunt and tubercular, slightly larger than, and situated slightly ventromedial to, the supraglenoid tubercle. Infraglenoid tubercle present as a short, broad, shallow and rugose fossa that abuts the caudal margin of the glenoid.
The scapula of P. viator sp. nov. cannot be confidently differentiated from that of P. mamkurra sp. nov. due to the fragmentary and juvenile nature of the material of the latter. It differs from that of P. anak in being less broad, with a thicker and less medially extensive spine; from C. kitcheneri in being larger, with a relatively slightly larger supraspinous fossa, a thicker, lower and less medially extensive scapular spine, a less anteroposteriorly compressed glenoid fossa, and a less anterolaterally projected supraglenoid tubercle and coracoid process;from O. rufus in being relatively slightly broader, with a slightly less medially extensive spine and a less anteroposteriorly compressed glenoid fossa; from M. fuliginosus in being larger, with slightly less medially extensive spine and a more lobe-shaped, less laterally extensive acromion; and from W. bicolor in being larger, with a less medially extensive caudal component and a thicker, less medially extensive and more cranially tilted spine.
Humerus (Fig. 67a–d): sexually dimorphic, with humeral length greater in males than in females. Humerus quite short and robust with thick, well-developed ridges for muscle attachment, becoming considerably more robust and muscle-scarred in older individuals (e.g. SAMA P59550). Humeral head roughly hemispherical, rounded and moderately caudomedially projected. Greater tubercule large to very large, broad and craniocaudally compressed, ranges from level with humeral head dorsally to markedly taller. Lesser tubercule quite tall, subequal with or slightly taller than head; blunt and rounded in lateral view, deep and oval in dorsal view; very small in juveniles. Proximal shaft robust and deep; in cranial view, the proximal component of the shaft has a slight medial deflection, with the axis situated across the shaft at the pectoral crest (e.g. SAMA P53836). Bicipital groove broad and very shallow in juveniles, becomes deeper, slightly narrower and distally more extensive in adults. Pectoral crest thick, high, elongate, rugose and slightly laterally tilted, extends distally to two-thirds of humeral length; becomes higher and more pronounced proximally with age. Deltoid tuberosity situated on the lateral surface of the shaft, level with the proximal part of the pectoral crest; low and gently rugose in juveniles, becoming thicker, more rugose and rounded to slightly pointed in adults. Insertion of m. latissimus dorsi marked by a small rugose area in juveniles and a broad, shallow, irregular fossa in adults.
Distal end broad and quite short.Lateral supracondylar ridge quite broad, extends slightly more than one-third of humeral length to adjacent to the distal margin of the pectoral crest, comes to a small, rounded point proximally. Capitulum and ulnar facet large, robust, laterally situated, abutting the lateral epicondyle; combined width roughly two-thirds of the epicondylar width; capitulum smoothly and strongly convex with a rounded, tapering lateral margin; ulnar facet with a relatively straighter medial margin with a gently bevelled edge; trochlea wide and quite shallow. Olecranon fossa large, extensive proximally, and moderately deep, becoming deeper with age. Radial fossa and coronoid fossa small and fairly shallow. Medial supracondylar bridge broad, quite thin craniocaudally; very thin to absent in juveniles. Supracondylar foramen oval, elongate and moderately flattened craniocaudally. Medial epicondyle comes to a rounded, medially projected point.
The humerus of P. viator sp. nov. differs from that of P. anak in being shorter, with a shorter pectoral crest, relatively slightly broader distal end, and a more convex lateral margin of the lateral supracondylar ridge; from P. mamkurra sp. nov. in having the peak of the lateral supracondylar ridge less pointed and closer to the distal margin of the pectoral crest; from P. tumbuna in being more robust, in lacking a low, rounded ridge linking the medial supracondylar bridge with the distal end of the pectoral crest, and in having a relatively shorter distal end; from P. otibandus in being larger; from C. kitcheneri in lacking a crest on the distal margin of the attachment site for the m. latissimus dorsi, and in having a more medially projected head, deeper, taller greater tubercle, taller lesser tubercle, more deeply concave bicipital groove, deeper proximal shaft, less elongate, generally less raised deltoid tuberosity, straighter, less raised pectoral crest, more elongate distal end, broader lateral supracondylar ridge with a more pointed proximal peak, and a broader medial supracondylar bridge; from O. rufus in being more robust, lacking a shallow fossa immediately distal to the supracondylar foramen, and in having a larger lesser tubercle, deeper proximal shaft, smaller, blunter deltoid tuberosity, thicker, more raised pectoral crest, and a relatively broader distal end; from M. fuliginosus in being generally larger and more robust, with a deeper, taller greater tubercle, deeper proximal shaft, less raised deltoid tuberosity, straighter pectoral crest, relatively broader distal end, broader capitulum and ulnar facet, ulnar facet with a less squared medial margin, and a shallower trochlea; and from W. bicolor in being larger, with a more medially projected head, taller, deeper greater tubercle, deeper, less raised and less elongate deltoid tuberosity, straighter, less raised pectoral crest, broader distal end, and a broader medial supracondylar bridge.
Ulna (Fig. 67e–g): large, elongate, quite deep and moderately transversely compressed. Olecranon quite short relative to ulnar length, and transversely compressed, tapering in lateral view to a blunt, squared distal end; a small, triangular process projects medially from the ventral component of the epiphysis; robustness, height, degree of transverse compression and relative length of olecranon are much less in juveniles than in adults. Facet for humeral articulation broad, with the trochlear notch broadly rounded and indistinct; medial component deeply concave, more elongate and situated more cranially than the lateral component, with the medial margin having a slight concavity between the convex margins of the anconeal and coronoid processes; lateral component relatively shallow, smoothly concave, and tilted and projected laterally. Anconeal process low relative to the coronoid process, with a rounded, reflex mesial angle; coronoid process tall, quite broad, and smoothly rounded in posterior view, meets the shaft at abrupt angle on cranial margin. Radial facet broad and roughly semicircular. Ulnar tuberosity narrow, quite elongate, slightly rugose and flat to gently concave. Lateral surface of ulna convex proximally, becoming flat toward the midpoint of the shaft; proximomedial flexor fossa gently concave. Shaft gently medially curved in cranial view; proximal component deep and highly transversely compressed, curved gently cranially, straightens distally; ventral surface broadest beneath the olecranon, tapers slowly anteriorly; broad, low ridge arises on the lateral margin of the cranial surface of the shaft midway between the ulnar tuberosity and the midpoint of the shaft; distal component of the shaft slightly broader and less tall than proximally, but remains transversely compressed. Distal epiphysis with a broad, rounded base, abruptly narrows to a short, medially hooked styloid process with a globular tip; a small, squared projection is on the caudolateral face of the base of the epiphysis for articulation with the pisiform.
The ulna of P. viator sp. nov. differs from that of P. anak in being generally broader and less elongate, with a longer olecranon and the distal shaft more transversely compressed and less cylindrical; from P. mamkurra sp. nov. in being more gracile, with a longer olecranon relative to total length; from P. tumbuna in being larger; from P. otibandus in being lower and less dorsoventrally compressed, with a relatively shorter olecranon, less deeply concave humeral facet, taller, broader coronoid process, and a shallower proximomedial flexor fossa; from C. kitcheneri in being larger, deeper and more robust, with a relatively longer olecranon, less raised trochlear notch, broader humeral facet, less rounded radial facet, and the shaft height tapering more distally; from O. rufus in being deeper and more robust, with a less dorsally deflected, longer olecranon relative to ulnar length, taller, more medially flared coronoid process, less laterally tilted lateral component of the humeral facet, less bilobed lateral margin of the humeral facet, broader, less laterally tilted radial facet, and a more transversely compressed shaft; from M. fuliginosus in being larger and more robust, with shallower and more elongate humeral facet, lower anconeal process, lower, more medially flared coronoid process, and a less bilobed lateral margin of the humeral facet; and from W. bicolor in being larger, with a less dorsally projected, less cranially deflected olecranon, much less medially flared anconeal process, lower coronoid process, broader radial facet, and a lower cranial ridge on the shaft.
Radius (Fig. 66d–e): elongate and straight to slightly curved. Radial head circular to slightly oval and smoothly concave. Radial neck tapers slightly to the radial tubercule. Radial tubercule rugose, round to oval and smoothly projected. Shaft cross-section is oval to tear-drop shaped immediately distal to the radial tubercle, becomes a gently craniocaudally compressed oval in the middle to distal shaft; shaft gently broadens distally from the midpoint. Cranial ridge broad, distinct, situated proximally, on the cranial surface midway between the radial tubercle and the midpoint of the shaft (Fig. 66e). Caudal ridge very low, indistinct and slightly rugose, located on the caudolateral surface of the middle of the shaft. Ulnar notch broad, quite shallow and elongate. The distal epiphysis is quite large; scaphoidal facet broad, gently caudally tilted and concave; cranial component of the distal surface gently convex; a small, blunt tubercle is on the caudolateral margin; styloid process quite large, slightly transversely compressed, medially situated and slightly curved caudally.
The radius of P. viator sp. nov. differs from that of all compared taxa in having a more proximally situated cranial ridge (bar P. tumbuna, for which no proximal radius is known), for the origin of the m. extensor carpi radialis. It further differs from P. anak in having the caudal ridge lower and less distinct; from P. mamkurra sp. nov. in being more elongate and generally less curved, with a lower, less distinct caudal ridge and a less craniocaudally compressed distal shaft; from P. tumbuna in being larger, with a lower, less distally extensive caudal ridge, more craniocaudally compressed distal shaft, and a smaller styloid process relative to the scaphoidal facet; from P. otibandus in being generally larger, with a less raised caudal ridge; from C. kitcheneri in being larger, with a thicker, more raised cranial ridge, less raised caudal ridge, and a caudally tilted (rather than slightly cranially) scaphoidal facet; from O. rufus in being more robust; from M. fuliginosus in being larger, with a more transversely compressed proximal shaft and a larger medial part of the distal epiphysis; and from W. bicolor in being larger, lacking a short caudomedial ridge on the distal shaft, and in having a thicker raised cranial ridge, less raised, less elongate caudal ridge, and a longer, less transversely compressed styloid process.
Manus
Scaphoid (Figs 68a–c & 69a–d): broad and robust, roughly semicircular in dorsal view; dorsopalmarly short and slightly arched in anterior view. Radial facet broad, tilted slightly dorsally, extends from the posteromedial margin, across the proximal surface, to the posterior margin of the palmar process; rounded and smoothly convex laterally, gently concave medially. Palmar process broad, lobe-shaped, highly dorsopalmarly compressed and anteropalmarly projected. Facet for the hamatum quite broad and convex, covers the lateral component of the anterior surface. Facet for the capitatum large, quite tall and concave. Facet for the trapezoid small and oval, abutting the capitatal facet on the anterodorsal margin of the palmar process. Facet for the trapezium broad and strongly convex with indistinct margins, wraps around the anterior surface of the palmar process.
The scaphoid of P. viator sp. nov. differs from that of P. mamkurra sp. nov. in having a broader palmar process, and hamatal and capitatal facets more distinct from each other, with the mesial component thickened instead of having a distinct, raised transverse dorsal ridge for articulation with the styloid process of the radius; from P. otibandus in being larger, lacking a raised dorsal ridge, and in having a more flattened radial facet and a more dorsopalmarly compressed palmar process; from C. kitcheneri in being broader, with a concavity present on the medial component of the radial facet, a broader, more anteropalmarly deflected palmar process, hamatal and trapezoidal facets more discrete, and the hamatal facet strongly convex (instead of concave and palmarly tilted); from O. rufus and M. fuliginosus in being larger, lacking a raised dorsal ridge, and in having the radial facet positioned more on the posterior surface and less dorsally; and from W. bicolor in being much larger, with a more concave capitatal facet and a larger hamatal facet.
Pisiform (Fig. 69e–j): quite broad, with an anteroposteriorly flared, flattened distal (lateral) end, a narrow waist and a large, posteriorly squared proximal end. Facet for the ulna has a large and flat posterior component, with a rounded medial lip; facet extends onto the medial surface and narrows to a slightly concave area of articulation for the styloid process of the ulna. Facet for the triquetrum rounded, convex and situated on the anteromedial surface; continuous posteriorly with the facet for the styloid process.
The pisiform of P. viator sp. nov. differs from that of P. otibandus in being larger, with a taller proximal end and a much larger, flatter posterior ulnar facet (Fig. 69j); from C. kitcheneri in being larger and less dorsopalmarly compressed, with narrower waist, more flared distal end and more distinct facets; from O. rufus in being larger and broader, with more distinct waist; from M. fuliginosus in being larger, with smaller anterodorsal eminence on proximal end; and from W. bicolor in being much larger, more robust and less dorsopalmarly compressed, particularly proximal end, with deeper distal end and taller, flatter facet for the styloid process.
Hamatum (Figs 68a–c & 70a–c): broad, robust and roughly boot-shaped in dorsal view. Posteromedial component large, squarish and projected. Facet for the triquetrum large, broad, occupies posterior surface except for posterior of palmar process; anterior component tall, slightly concave and faces directly posteriorly, with flared, convex dorsal margin in posterior view; posterior component lower, slightly dorsally tilted, gently convex and faces posterolaterally, situated on posteromedial process of the hamatum. Facet for the scaphoid small and dorsopalmarly concave, abuts medial margin of triquetral facet on posteromedial surface. Facet for the capitatum gently concave, roughly arch-shaped on anteromedial surface, curves over small, deep foramen; continuous with facet for lateral surface of proximal end of metacarpal III, semicontinuous posteriorly with scaphoidal facet, meeting at sharp corner. Facet for metacarpal IV rounded and smoothly concave, with convex lateral lip extending palmolaterally onto anterior surface of palmar process; indistinct from facet for metacarpal V. Palmar process thick and blunt, projects palmarly and slightly laterally from lateral component.
The hamatum of P. viator sp. nov. differs from that of P. mamkurra sp. nov. in being deeper, with a more concave scaphoidal facet, narrower combined metacarpal IV and V facets relative to the capitatal and metacarpal III facets, shorter, blunter, posteropalmarly projected palmar process (Fig. 70b), and a convex metacarpal V facet; from P. otibandus in being larger, with triquetral facet more extensive medially to be semicontinuous with, rather than distinctly separate from, the scaphoidal facet; from C. kitcheneri in being slightly larger and more robust, with the posteromedial component more squared, more dorsally flared, more concave triquetral facet that is semicontinuous medially with the scaphoidal facet, more concave facet for metacarpal IV, smaller, less concave and less laterally rotated facet for metacarpal V, and an anteroposteriorly deeper, less projected and less anteriorly deflected palmar process; from O. rufus in being larger, with the triquetral and scaphoidal facets semicontinuous and the palmar process relatively smaller, blunter and lacking anterior deflection for articulation with the palmar surface of metacarpal V; from M. fuliginosus in being larger, with a relatively smaller medial component and a dorsopalmarly shorter dorsolateral margin of the triquetral facet; and from W. bicolor in being much larger, with a less deeply concave triquetral facet, relatively larger facet for metacarpal III, and a much less palmarly extensive palmar process.
Capitatum (Figs 68a–c & 70d–g): quite small, and rectangular to roughly oblong in dorsal view, with the palmar surface roughly triangular due to narrowing of the posteropalmar margin into a short, cone-like point. Facet for the hamatum squarish and slightly concave to slightly convex, with a posterior tilt; occupies majority of lateral surface; a small, rounded fossa sits against the anteropalmar margin. Facet for the scaphoid concave medially, becoming gently convex laterally; covers the posteromedial surface and extends laterally, with a slight palmar curve, to wrap around the posterior edge where it is continuous with the hamatal facet. Facet for metacarpal III large, covers the anterior surface and subdivides into a semicontinuous smaller medial component and a larger lateral component for the medial and lateral processes of the posterior end of metacarpal III. Medial surface anteroposteriorly short, with a tall, concave facet for the medial part of the posterior facet of metacarpal II occupying the anterior section. Facet for the trapezium very narrow and indistinct, on the posteropalmar section of the medial surface.
The capitatum of P. viator sp. nov. differs from that of P. mamkurra sp. nov. in being deeper, having a larger posteropalmar process, and lacking a small, rounded dorsoposterior fossa; from P. otibandus in being larger; from C. kitcheneri in being squarer in dorsal view, with a larger posteropalmar process, taller medial section of metacarpal III facet, and a taller, narrower and more medially situated facet for metacarpal II; from O. rufus in being larger and deeper; from M. fuliginosus in being larger, generally squarer and deeper, with a larger and more pointed posteropalmar process; and from W. bicolor in being much larger, and slightly deeper in dorsal view, with larger, deeper hamatal facet.
Trapezoid (Figs 68a–c & 70h–j): considerably smaller than the trapezium; very small and palmomedially abraded; positioned between the capitatum and trapezium with a slight dorsal displacement. Facet for the capitatum tall, narrow and gently convex. Facet for the scaphoid fairly narrow and gently concave. Facet for the trapezium mostly abraded in available specimen; preserved is a small, pointed anteromedial eminence for articulation with the posterolateral surface of the dorsolateral eminence of the trapezium. A very small, roughly triangular facet is on the anterior surface for articulation with metacarpal II.
The trapezoid of P. viator sp. nov. differs from that of all compared taxa in having a smaller articulation with metacarpal II. It further differs from C. kitcheneri in being smaller relative to the capitatum; from O. rufus and M. fuliginosus in being smaller relative to the trapezium; and from that of W. bicolor in being absolutely larger, and smaller relative to the trapezium.
Trapezium (Figs 68a–c & 70k–l): considerably larger than the trapezoid; broad and trapezoidal in anterior view, with a large, pointed eminence against the lateral margin on the anterodorsal surface for articulation with the anteromedial surface of the trapezoid and with the dorsal component of the posterior surface of metacarpal I; articulates with the dorsoanterior surface of the palmar process of the scaphoid, such that the broad, dorsally tapering and dorsally concave facet for metacarpal I faces anteriorly. Facet for the scaphoid broad and deeply, smoothly concave. Facet for metacarpal I has a larger, rounded medial section that continues laterally into a smaller, gently convex dorsolateral section on the pointed anterolateral eminence.
The trapezium of P. viator sp. nov. differs from that of P. mamkurra sp. nov. in being slightly narrower, with a more pointed medial margin; from C. kitcheneri in having a more concave facet for the palmar process of the scaphoid; from O. rufus and M. fuliginosus in being larger relative to the trapezoid, with a more pointed anterolateral eminence and a more distinct facet for metacarpal I with more discrete medial and lateral sections; and from W. bicolor in being absolutely larger and larger relative to the trapezoid, with a more deeply, smoothly concave facet for the palmar process of the scaphoid and a broader, more distinct facet for metacarpal I.
Metacarpals (Figs 68 & 71a–e): sexually dimorphic, with males exhibiting significantly greater robustness and greater length of metacarpals than females; metacarpals II–IV most elongate; each narrows to a distinct waist. Metacarpals I and V: proximal ends have a large, blunt tubercle on the medial and lateral surfaces respectively; both with distal ends distinctly asymmetrical, skewed mesially. Metacarpal IV: broad proximal facet for articulation with the capitatum, tilted dorsally and slightly medially; facet for metacarpal V faces laterally, abuts the lateral margin of the capitatal facet on the lateral surface of the proximal end. Metacarpal III: longest, with the proximal end separated into a longer, medially deflected medial process and a very short, laterally deflected lateral eminence; distal end has a particularly large, palmodistally prominent keel. Metacarpal II: slightly shorter than III and IV and considerably more gracile; lateral margin of the proximal end wraps slightly around the proximomedial margin of metacarpal III. Metacarpal I: shortest, with the tall, narrow proximal facet for the trapezium slightly laterally situated and tilted dorsally.
The metacarpals of P. viator sp. nov. differ from those of P. anak in being more gracile, with metacarpal V facet on metacarpal IV distinctly lateral facing (rather than anterior facing) (Fig. 71b); from P. mamkurra sp. nov. in being more gracile, with a relatively narrow distal end of metacarpal III and a less dorsally tilted proximal articular surface on metacarpals IV and V; from P. otibandus in being larger and more gracile, with a lateral facing metacarpal V facet on metacarpal IV; from C. kitcheneri in being more elongate, with generally broader proximal articular surfaces, more pronounced waists, and less convex distal articular surfaces; from O. rufus in being larger and more gracile, with much larger proximomedial and proximolateral tubercles on metacarpals I and V respectively; from M. fuliginosus in being larger, with metacarpals I and V more gracile and with much larger proximomedial and proximolateral tubercles; and from W. bicolor in being much larger and slightly less dorsopalmarly compressed, with a larger proximolateral process on metacarpal III.
Manual phalanges (Figs 68d & 71f–h): short and robust relative to metacarpals, excluding distal phalanges III and IV, which are quite elongate; proximal and middle phalanges are increasingly symmetrical mesially. Proximal phalanges: broad; proximal and distal articular surfaces gently concave; proximal articular surfaces slightly dorsally tilted, with low, rounded palmar tubercles slightly proximally projected beneath. Middle phalanges: extremely short, broad and dorsopalmarly compressed, with gently dorsally tilted proximal articular surfaces, and shafts lacking a waist. Distal phalanges: quite long, with a large palmar tubercle, and shafts gently palmarly curved and highly dorsopalmarly compressed; broader in males than in females.
The manual phalanges of P. viator sp. nov. differ from those of P. anak in having proximal phalanges with slightly less dorsally tilted proximal surfaces and shallower, very gently concave (rather than broadly V-shaped) trochleae, and distal phalanges with more palmarly curved shafts; from P. mamkurra sp. nov. in being generally shorter, with proximal phalanges with slightly less dorsally tilted proximal surfaces, and distal phalanges slightly more palmarlycurved,narrower,less dorsopalmarlycompressed (less spatulate) with larger and more palmarly projected palmar tubercles; from P. otibandus in being larger and relatively short and robust, with more dorsopalmarly compressed distal phalanges with smaller palmar tubercles; from C. kitcheneri in being significantly shorter relative to the metacarpals, relatively broader and far more dorsopalmarly compressed (particularly the middle phalanges), with broader and less V-shaped trochleae, and dorsally rounded (un-peaked) distal phalanges with less palmar curvature of the shaft; from O. rufus in being larger, more robust and more dorsopalmarly compressed, with relatively shorter proximal phalanges, and relatively longer distal phalanges with more palmarly curved shafts; from M. fuliginosus in being larger and relatively short and robust, with much more dorsopalmarly compressed and spatulate distal phalanges; and from W. bicolor in being much larger, relatively broader and more robust, with less dorsally tilted proximal surfaces on the proximal phalanges.
Hindlimb
Pelvis (Fig. 72): ilium, ischium and pubis unfused in juveniles. Ilium: robust, well-developed and roughly Lshaped in cross-section. Iliac crest thick, broad, gently rounded along the dorsal margin, aligned transversely and projected slightly laterally; extends onto the dorsal end of the caudal iliac spine; ilium gently increases to maximum width at the iliac crest. Iliac fossa extends around three-quarters of the length of the ilium in adults, shorter and shallower in juveniles; extends from craniodorsal to the acetabulum and curves along the lateral surface of the cranial iliac spine; quite deeply concave proximally, becomes shallower distally. Gluteal fossa broad and deeply concave, extends to the iliac crest. Caudal iliac spine arises on the caudomedial surface of the base of the ilium opposite the rectus tubercule and projects caudally; thick and deep in proximal component for the origin of a large mm. gluteus, becomes steadily thinner and lower distally, extends to the iliac crest. Sacral surface large, very rugose and concave; articular surface for the wings of the sacrum deep and aligned craniocaudally with a slight cranial tilt; sacral surface deeper in older specimens such that the cranial margin projects cranially as a broad, low ridge with a thin crest (the cranial iliac spine) to contribute to the depth of the iliac fossa. Lateral iliac spine very broad, thin relative to the caudal spine; margin slightly and irregularly concave, curves laterally to projected dorsolateral extremity at the iliac crest. Rectus tubercule quite large, rugose, roughly triangular, narrows rapidly onto the lateral spine; increases in relative size with age.
Acetabulum large, tall and deeply concave; taller than depth, deepest in the proximal section; acetabular fossa deep, with the angle, width and curvature variable within individuals; partially covered cranially and caudally by a lip projecting from the acetabular surface; poorly developed in juveniles, with the cranial and caudal margins relatively very low. Ischium: very deep ventral to the acetabulum, transversely compressed, gently concave on medial surface and convex on lateral surface; caudal margin gently rugose and undulating from the origin of the mm. gemelli; deflected slightly caudally relative to the axis of the ilium; caudal component broadens toward the broad, laterally projected ischiatic tuberosity; caudal surface of the dorsal section of the ischium (caudally adjacent to the acetabulum) very broad, convex and rugose; caudomedial surface of the ischium has a broad, smoothly concave fossa. The iliopubic eminence is a slightly projected rounded point, broad and rugose. Craniodorsal angle of the obturator foramen is acute and rounded, with the ventral angle broadly rounded and obtuse. Pubis: narrows ventral to the iliopubic eminence, broadens and craniocaudally flattens toward the pubic tubercle; becomes significantly more robust and broader at the dorsal base with age. Ischiatic table tall, deep and transversely compressed.
The pelvis of P. viator sp. nov. differs from that of P. mamkurra sp. nov. in having a slightly broader lateral iliac spine and a shorter rectus tubercle; from P. tumbuna in having a more curved caudally ilium in lateral view, a less laterally projected rectus tubercle, acetabulum opening laterally and less cranioventrally, larger iliopubic eminence, and a narrower, more planar ischium that is slightly longer relative to ilium length and slightly caudally deflected relative to the axis of the ilium in lateral view; from P. dawsonae sp. nov. in being larger, with a slightly deeper caudal iliac spine, more deeply concave gluteal fossa, broader, more rugose and more convex caudal surface of the dorsal section of the ischium, and a more deeply concave acetabulum; from C. kitcheneri in being larger, with a far broader, deeper gluteal fossa, narrower, less distally extensive iliac fossa, more rounded cranial iliac spine, more caudally and dorsally situated sacral surface relative to the acetabulum, and a rounder, shallower acetabulum; from O. rufus and M. fuliginosus in being generally larger and more robust, with a far broader and deeper gluteal fossa, a less distally extensive iliac fossa, more rounded cranial iliac spine, broader lateral iliac spine, and a greater maximum acetabulum diameter relative to ilium length; and from W. bicolor in being far larger, having the caudal iliac spine lack a small, pointed eminence on the caudoventral shoulder, and in having the iliac crest aligned more transversely and less craniocaudally, a broader, deeper gluteal fossa, a narrower, less distally extensive iliac fossa, broader lateral iliac spine (particularly dorsally), rectus tubercle with a smaller, shallower fossa on lateral surface, and a higher, more distinct dorsoventral ridge leading to the lateral surface of the ischiatic tubercle.
Epipubic (Fig. 59): thin, straight and flattened; broadens and thickens to the proximal articulation with the pubis.
The epipubic of P. viator sp. nov. differs from that of C. kitcheneri in being larger and more gracile; from O. rufus and M. fuliginosus in being more robust at the pubic articulation; and from W. bicolor in being much larger.
Femur (Fig. 73): large, short and robust, with the shaft straight in dorsal view and very slightly bowed dorsally in lateral view. Head large, hemispherical, dorsomedially projected and flared dorsally. The greater trochanter is not known; greater trochanteric ridge very broad, thick, slightly ventrally arched and laterally projected to form a raised, rugose proximolateral ridge on the dorsolateral margin of the proximal end (Fig. 73a); proximolateral ridge more raised and distally longer in more mature specimens; probable origin point for an enlarged m. vastus lateralis. Trochanteric fossa extends distally to level with the lesser trochanter. The proximal end is very broad, with a smoothly, distinctly convex dorsal surface. Intertrochanteric crest raised, ventromedially projected and very distinct, extends distomedially from the ventromedial base of the greater trochanter to the lesser trochanter. Lesser trochanter is a large, rugose eminence, projected medially from the proximal end and slightly ventrodistal to the head, situated at medial peak of a broadly obtuse (110–120°), medially projected conjunction of the intertrochanteric crest and the lesser trochanteric ridge; lesser trochanteric ridge thick, very raised and strongly medially projected, particularly in older individuals, extends distolaterally with slight dorsal deflection to merge into the femoral shaft between one-third and half of femoral length.
Femur shaft round to very slightly transversely compressed in cross-section; width tapers to a minimum around the midpoint and broadens to the distal end; ventral surface gently convex, becomes planar and gently medially tilted distally; in some specimens (see NMV P173087), lesser trochanteric ridge extends as a very low, rounded ridge to merge into the shaft near to the quadratus tubercle. Quadratus tubercle situated between one-third and midpoint of the length of the shaft, on the ventral surface of the shaft with a slight medial displacement; large, raised, rugose, elongate and oval, with a tapering rugose patch extending proximally to adjacent to or onto the proximal end. A small, deep fossa sits on the proximoventral margin of the lateral condyle on the ventrolateral surface of the shaft, continuing into a broad, shallow fossa on the proximal surface of the lateral condyle; lateral fabellae preserved between these fossae and the caudolateral margin of proximal tibial epiphysis in SAMA P53835a and SAMA P59550 indicate the partial origin of the m. flexor digitorum superficialis from a thick tendon in these two fossae.
Femur distal epiphysis large, robust and quite tall. Trochlea quite wide, deep and with the concavity approaching V-shaped, distinctly medially skewed and displaced (Fig. 73e). Trochlear crests tall, with the medial crest considerably lower and narrower than the lateral crest. Intercondylar fossa variably narrow (see SAMA P25203 versus SAMA P59550) and very deep, broadest at the midpoint before narrowing to the slightly laterally displaced ventrodistal component. Condyles broadest across the ventral surfaces, with the lateral condyle slightly broader and quite concave laterally, due to the lateral projection and ventral deflection of the lateral epicondyle for the well-developed fibular facet; lateral condyle larger and broader in distal view.Both epicondyles increase in size with age, with an associated increase in the size and depth of the fossae. Lateral epicondyle very large, tall and strongly laterally projected, particularly the ventral part, with a slight ventral deflection in distal view; a small, deep, rounded fossa on the distal margin of the ventral part and a broad, shallow, rounded fossa on midpoint of lateral surface are for the origins of the m. gastrocnemius lateralis. Medial epicondyle relatively flat and unprojected, with a small, deep, rounded mesial fossa for the attachment of the m. gastrocnemius medialis.
The femur of P. viator sp. nov. differs from other species of Protemnodon in being relatively shorter and more robust, with a more raised and more distinct intercondylar crest, and a more medially projected lesser trochanter and lesser trochanteric ridge forming a large, medially projected triangular crest ventral to the femoral head. Further differs from that of P. mamkurra sp. nov. in having a more raised proximolateral ridge, a narrower, deeper trochlea, narrower trochlear crests, medial trochlear crest coming to a more pointed peak, and a less medially projected ventral part of the medial epicondyle; from P. anak in having a narrower medial trochlear crest and a deeper, narrower trochlea; from P. tumbuna in being larger, with a relatively less elongate and more proximally situated quadratus tubercle and the lateral trochlear crest coming to a narrower peak; from P. otibandus in being larger, with a more medially projected lesser trochanter and a broader ventral surface of the medial condyle; from C. kitcheneri in being larger and more robust, with higher intertrochanteric and proximolateral ridges, a more medially projected lesser trochanter, straighter and more distally extensive lesser trochanteric ridge, less medially displaced quadratus tubercle, deeper trochlea, more pointed medial trochlear crest, and a less distally situated lateral gastrocnemial fossa; from O. rufus in being larger and more robust, with relatively broader proximal and distal ends, a relatively larger head, more raised proximolateral ridge and intercondylar crest, more medially projected lesser trochanter, straighter and more distally extensive lesser trochanteric ridge, more elongate quadratus tubercle, shallower fossa for the partial origin of the m. flexor digitorum superficialis, less raised trochlear crests, more laterally projected lateral epicondyle, and a more proximally situated lateral gastrocnemial fossa; from M. fuliginosus in being larger and more robust, with a less distally extensive trochanteric fossa, a more raised, distinct intercondylar crest, more medially projected lesser trochanter, more raised proximolateral ridge, longer lesser trochanteric ridge, longer, more proximally extensive quadratus tubercle, shorter distolateral fossa for the origin of the m. flexor digitorum superficialis, relatively slightly more raised dorsal section of the medial condyle, more dorsodistally extensive intercondylar fossa, and a more proximally situated lateral gastrocnemial fossa; and from W. bicolor in being larger and considerably more robust, with a relatively larger, more dorsally deflected head, a more medially projected lesser trochanter, less distally extensive trochanteric fossa relative to head, much more distally extensive lesser trochanteric ridge, more raised proximolateral crest, less dorsoventrally compressed distal shaft, broader, less raised trochlear crests, shallower trochlea, larger fibular facet on lateral condyle, and a more laterally projected lateral epicondyle.
Tibia (Fig. 74): large and elongate. In cranial view, the proximal component is bowed very slightly medially, but the distal shaft is quite straight. Proximal epiphysis deeper than width; medial condyle narrow, deep and slightly projected caudally; lateral condyle much less deep, smaller and more extended laterally with a large, concave muscular groove in the craniolateral margin. Proximal fibular facet elongate, narrow and shelf-like, orientated ~40° from the sagittal plane. Cnemial crest deep and elongate, with an indistinct, rugose, curved distal peak, below which it slowly thickens and merges with into the midpoint of the shaft; lateral surface gently concave and medial surface very slightly convex. Proximolateral crest thin and very raised, extends and thickens distally to merge into the distal fibular facet on the distolateral surface of the shaft. Shaft elongate; minimum shaft diameter is in the distal quarter, with the diameter increasing gently to the distal epiphysis. Distal fibular facet extends on the lateral surface from slightly proximal to the midpoint of the shaft to immediately proximal to the distal epiphysis. Distal epiphysis robust; talar trochlea roughly square, gently concave and with the cranial part projected to face the articular surface caudally; medial tuberosity narrow and very deep with a blunt medial malleolus.
The tibia of P. viator sp. nov. differs from that of all species of Protemnodon except P. snewini in being more gracile. It further differs from P. anak in having a straighter distal shaft in cranial and lateral views; from P. mamkurra sp. nov. in being longer and in having a less laterally curved cnemial crest with a more angular and distinct distal peak, a thinner proximal section of the proximolateral crest, and a straighter distal shaft in cranial view; from P. tumbuna in being larger, much longer, and straighter in cranial view, with a more angular and distinct peak of the cnemial crest; from P. otibandus in being larger, with a shallower proximal fibular facet, narrower intercondylar eminence, narrower and less rounded cranial section of the proximal epiphysis, and a more angular, distinct peak of the cnemial crest; from P. snewini in being more robust, with a deeper, narrower proximal epiphysis; from C. kitcheneri in being larger and more gracile, with a relatively narrower proximal epiphysis, taller intercondylar eminence, more raised proximal part of proximolateral crest and relatively deeper shaft with greater expansion to distal epiphysis; from O. rufus in being more robust, with a more laterally deflected cranial section of the proximal epiphysis, more elongate cnemial crest, slightly thicker and weaker proximolateral crest, and a shorter distal shaft relative to the proximal shaft; from M. fuliginosus in being larger and more robust, with a more laterally curved cnemial crest and a straighter shaft in lateral view; and from W. bicolor in being larger, having the proximal epiphysis with a deeper intercondylar eminence and a narrower, less cranially tilted cranial component, and in its more raised proximolateral crest and larger talar trochlea.
Fibula (Fig. 74): elongate and curved very slightly caudally toward the proximal end. Proximal epiphysis large and deep; caudal process for articulation with the fibular facet on the lateral condyle of femur is proximally projected, tall, deep and narrow; a large, blunt tubercle is present on the lateral surface of the base of the epiphysis, probably for the origin of the m. flexor digitorum profundus; a small, deep concavity for the tibiofibular ligament sits at the craniolateral base of the process for femoral articulation. Proximal shaft initially roughly triangular in cross-section, narrows to flattened distally, then broadens slightly and tapers craniocaudally before flaring craniocaudally to the distal epiphysis; a broad, deep groove extends down the caudomedial surface of the shaft from the proximal epiphysis; fibula first articulates with the tibial shaft two-fifths of the distance to the distal end, after which the fibular shaft narrows and deepens, becoming thin and slightly crescentic in cross-section. Some specimens (see SAMA P59550) have a narrow lateral groove extending from the distal shaft onto the lateral surface of the epiphysis. Distal epiphysis large and deep, narrows cranially. Calcaneal facet has a narrow, flat caudal section that is tilted strongly medially to be almost blade-like, then broadens and rotates to face ventrally in its smoothly rounded, gently convex cranial section.
The fibula of P. viator sp. nov. differs from that of P. anak in having a relatively narrower distal epiphysis with a shallower lateral groove and a broader, less medially slanted caudal calcaneal facet; from P. mamkurra sp. nov. in being longer, with a deeper, narrower proximal shaft, and stronger broadening and craniocaudal tapering of the distalmost shaft before the epiphysis; from C. kitcheneri in being larger, with relatively larger proximal and distal epiphyses and a deeper distal shaft; from O. rufus in being much more robust, with a relatively larger, deeper proximal epiphysis and a deeper distal shaft; from M. fuliginosus in being larger and more robust, with a larger lateral tubercle on the proximal epiphysis, a relatively taller process for articulation with the fibular facet of the femur, a much deeper distal shaft, and a more medially tilted caudal part of the calcaneal facet; and from W. bicolor in being larger and more robust, with a relatively larger proximal end and the distal shaft with a more distinct craniocaudal taper.
Pes (Fig. 75a–d)
Calcaneus (Fig. 76a–f): tall, fairly narrow and elongate. Calcaneal tuberosity tall, narrow and roughly triangular in cross-section; broadens caudally to a thickened caudal epiphysis; medial surface flat to gently concave and lateral surface gently concave, becomes deeply concave beneath the fibular facet. Caudal surface for the gastrocnemial tendon very tall and domed, with a narrow transverse groove across the midline, occasionally mesially kinked. Plantar surface rugose, triangular in plantar view, narrows to a rounded point cranially and extends to the level with the cranial margin of the sustentaculum tali; becomes thicker, broader and more rugose with age; a thickened caudal component arises from the caudal epiphysis.Cranial plantar tubercule small but distinct and plantomedially projected; sits immediately caudal to the plantar margin of the plantomedial cuboid facet.
The calcaneal head is large, tall and fairly narrow. Sustentaculum tali large and quite elongate caudally and plantarly, moderately medially projected, subequal to or slightly more than medial talar facet, with caudoplantar margin rounded and coming to blunted peak on the cranioplantar margin; thickens medially with age; flexor groove broad and deep. Fibular facet large and laterally projected, with cranial and caudal sections separated on lateral edge by a short, broad transverse groove and linked medially by a narrow section of facet semicontinuous with the lateral talar facet; caudal component small, caudal-facing, oval to smoothly triangular, slightly convex and with margins indistinct except for a crestlike, laterally projected lateral margin (Fig. 76a); cranial section larger and dorsally flat to concave with a convex, rounded lateral face. Lateral talar facet broad, convex and tapering very slightly medially, approaches square in dorsal view; a rounded, gently concave fossa of moderate depth sits immediately cranial to the lateral talar facet for articulation with the craniolateral end of the talus, with a small, blunt tubercle, more raised with age, on the medial margin of the fossa. Medial talar facet small, concave, cranially tilted, rounded to slightly craniocaudally compressed, caudally displaced relative to the lateral talar facet, with the cranial component inset into the dorsal surface of the calcaneal head; articular surface extends slightly onto the caudal surface to create a slight rounded lip.
Facet for the talar head small, abuts the medial margin of the dorsomedial facet on the medial surface of the calcaneal head. Dorsomedial cuboid facet broad, gently convex, rounded or oval to smoothly rectangular with rounded dorsomedial margin, generally broader than dorsolateral facet; occasionally dorsally displaced relative to dorsolateral facet; moderately deep, dorsoplantarly compressed fossa immediately plantar to dorsomedial cuboid facet. Dorsolateral cuboid facet tall, quite narrow, slightly concave to slightly convex and cranially projected; extends plantarly and slightly medially, narrowing to become the plantomedial facet. Plantomedial cuboid facet variable, but generally small, slightly convex, rounded in cranial view and not extending medially beyond the midpoint of the dorsomedial facet; slightly dorsoplantarly compressed in some specimens (see SAMA P50549); curves distinctly dorsomedially in some specimens.
The calcaneus of P. viator sp. nov. differs from that of other species of Protemnodon and of C. kitcheneri in being relatively taller, narrower and more gracile, and in having a less medially projected sustentaculum tali. It further differs from that of P. anak in having a less distinct, less rounded and more laterally projected caudal component of the fibular facet; from P. mamkurra in having a narrower plantar surface, a smaller, more caudally displaced medial talar facet, less convex lateral talar facet, smaller, less dorsally bulbous fibular facet, and a more rounded sustentaculum tali; from P. tumbuna in being larger, with a relatively broader dorsomedial cuboid facet, less medially displaced calcaneal head, and a planar, less medially flared plantar surface that is less rounded in plantar view; from P. dawsonae sp. nov. in being larger, with a more triangular, less rounded calcaneal tuberosity in cross-section, deeper lateral talar facet, and a narrower and more sagittally aligned medial talar facet; from P. otibandus in being larger, with a more triangular calcaneal tuberosity in cross-section, relatively broader dorsomedial cuboid facet, and the lateral surface of the calcaneal head beneath the fibular facet much taller and more concave; from C. kitcheneri in being larger, with a flatter, less laterally tilted and more cranially extensive plantar surface, a deeper, flatter lateral talar facet, and a less laterally tilted dorsomedial cuboid facet; from O. rufus in being larger and slightly broader, with a less laterally displaced head, more medially projected sustentaculum tali, no articular surface for the posterior plantar process of the talus, flatter and deeper lateral talar facet with a shallower cranial fossa, less cranially tilted medial talar facet, more dorsally projected fibular facets, plantar surface that broadens caudally, and a smaller cranial plantar tubercle; from M. fuliginosus in being larger and relatively taller, with a more medially projected sustentaculum tali, more caudally projected caudal fibular facet, and less laterally and more dorsally projected fibular facets; and from W. bicolor in being larger and relatively taller, with a more triangular tuberosity in cross-section, broader medial talar facet with rounded caudal lip, and a broader dorsomedial cuboid facet relative to dorsolateral facet.
Talus (Fig. 76g –i): large and robust, width greater than craniocaudal length. Trochlear crests equal in height, come to rounded points with the medial crest slightly more pointed; trochlea moderately shallow, with the concavity slightly medially skewed. Medial malleolus elongate, extends cranially and slightly medially, and mediocaudally tilted; malleolar fossa shallow, elongate and smoothly concave, with a slight ridge at the cranial margin that distinctly separates the fossa from the dorsal surface of the talar head. Talar head craniomedially projected and plantarly deflected. Articular facet for the navicular large and tall, extends caudoplantarly to beneath medial malleolus. Articular facet for the cuboid smaller and lateral facing, with a very slight cranioplantar tilt. Posterior plantar process short, thick and rounded. On the plantar surface, the medial calcaneal facet is craniocaudally short and deeply concave, with the cranial lip plantarly projected, and lateral calcaneal facet broad and smoothly concave.
The talus of P. viator sp. nov. differs from that of P. anak in lacking small indent between cranial margin of medial trochlear crest and talar head, and in having a less cranially projected talar head, medial malleolus more aligned in the sagittal plane, and the concavity of the trochlea more medially skewed; from P. mamkurra sp. nov. in having a less cranially projected talar head, with the malleolar fossa slightly more caudally situated and the navicular facet aligned in the sagittal plane (rather than curving plantomedially); from P. otibandus in being larger, with a shallower, more elongate and more caudally situated malleolar fossa and a more elongate and medially tilted medial malleolus; from C. kitcheneri in being larger and relatively slightly more elongate, with a less medially skewed trochlear concavity, a facet for the cuboid present on the talar head, and a more caudoplantarly extensive navicular facet; from O. rufus in being larger and relatively broader, with deeper trochlea, shallower malleolar fossa, less medially projected medial malleolus, less medially projected, more plantarly deflected talar head, more lateral facing cuboid facet, and a deeper, less projected posterior plantar process; from M. fuliginosus in being larger and relatively broader, with deeper trochlea, shallower malleolar fossa, less medially projected medial malleolus, less medially projected, more plantarly deflected talar head and larger cuboid facet; and from W. bicolor in being much larger, with a less medially skewed trochlear concavity, more caudoplantarly extensive navicular facet, and a more rounded posterior plantar process in medial view.
Cuboid (Fig. 76j–l): tall, robust, quite broad and roughly rectangular in dorsal view, with a step in the caudal margin for the calcaneal facets. Dorsolateral calcaneal facet quite tall, narrow and concave, continuous plantarly with the thin, elongate plantomedial facet. Dorsomedial calcaneal facet broad, squarish, concave and posteriorly projected, separated from the dorsolateral facet by a bevelled step. Facet for the talar head tall, thin, situated on the dorsal part of mediocaudal margin; slightly dorsally flares the caudal part of dorsomedial margin. Facet for the navicular small and rounded, occasionally indistinct, situated caudal to a tall fossa on the cranial part of the medial surface. Facet for the ectocuneiform tall and craniocaudally shallow, extends down the cranial margin of the medial surface onto the medial surface of the medial plantar tubercle. Dorsal metatarsal IV facet broad and slightly concave, covers the entire dorsal section of the cranial surface; medial component smoothly continuous with the slightly plantarly tilted plantomedial metatarsal IV facet; dorsal margin straight, becomes sinusoidal in cranial view in older individuals. Facet for metatarsal V quite large, broad, concave, rounded to oval and slightly laterally tilted, semicontinuous with the mediolateral margin of the dorsal metatarsal IV facet; separated from the plantomedial metatarsal IV facet by a moderately shallow, rugose fossa. Lateral plantar tubercle very large and plantarly projected, rounded to slightly elongate and oval in plantar view; caudal section occasionally extends dorsolaterally (see SAMA P25098). Medial plantar tubercle small, narrow, plantarly projected and quite elongate, separated from the lateral tubercle by the deep, narrow flexor groove.
The cuboid of P. viator sp. nov. differs from those of all species of Protemnodon in being taller and relatively narrower, with larger, more plantarly projected lateral and medial plantar tubercles and a deeper flexor groove (Fig. 76j–k). Further differs from that of P. anak and P. mamkurra sp. nov. in having a slightly more laterally situated medial plantar tubercle and a narrower flexor groove; from P. otibandus in being larger, with a more dorsally situated navicular facet and more elongate plantar tubercles; from P. snewini in being larger, with a more bevelled step between the dorsal calcaneal facets, more caudally tilted facet for the talar head, more medially situated medial plantar tubercle and broader flexor groove; from C. kitcheneri in being larger and taller, with a relatively narrower dorsomedial calcaneal facet, a facet for the talar head present, a larger, more plantarly projected lateral plantar tubercle, larger, more plantarly projected and more medially situated medial plantar tubercle, and a broader, deeper flexor groove; from O. rufus in being generally larger and relatively broader, with relatively broader dorsomedial calcaneal facet, more medially tilted facet for the talar head, more medially situated medial plantar tubercle, broader flexor groove and more medially situated plantar metatarsal IV facet; from M. fuliginosus in being larger and relatively deeper, with deeper navicular/ectocuneiform fossa on plantar component of medial surface, more medially situated medial plantar tubercle and broader flexor groove; and from W. bicolor in being larger and relatively taller, with more plantarly projected plantar tubercles and a deeper, narrower flexor groove.
Navicular (Figs 75e–f & 77): tall, very narrow and quite deep, with the width tapering slightly dorsally; caudal margin slightly taller than the cranial margin. Facet for the talar head gently concave, with the plantar section thickened and slightly caudally projected. Facet for the entocuneiform small and rounded, situated against the plantomedial margins of the cranial surface. Facet for the ectocuneiform tall and narrow, extends the entirety cranial surface, with plantar section lateral to the entocuneiform facet.
The navicular of P. viator sp. nov. differs from that of P. mamkurra sp. nov. in being broader, with a more plantarly extensive facet for the ectocuneiform; from P. otibandus in being larger and broader, and deeper relative to height, with a less laterally flared facet for the ectocuneiform and a more medially tilted facet for the entocuneiform; from C. kitcheneri in being larger, taller and narrower; from O. rufus in being larger, narrower and less deep relative to height, with less deeply concave facet for the talar head, narrower, slightly more laterally situated and less smoothly convex facet for the ectocuneiform, and lacking an eminence on the medial margin of the cranial surface between the ectocuneiform facet and entocuneiform facet; from M. fuliginosus in being larger, taller and narrower, with a slightly more laterally situated facet for the ectocuneiform and lacking an eminence on the medial margin of the cranial surface; and from W. bicolor in being much larger and relatively narrower.
Ectocuneiform (Figs 75e–f & 77): tall, highly transversely compressed, slightly tapered dorsally in medial view and very slightly convex medially in caudal view. Facet for the navicular tall, narrow and gently concave, occupies almost all of the caudal surface. Facet for the entocuneiform large and moderately to deeply concave, occupies plantar component of medial surface. Facet for metatarsal IV small and rounded, situated against craniodorsal margin of lateral surface. Facet for the cuboid tall, craniocaudally thin and tapers plantarly, covers majority of caudal component of lateral surface. Facet for metatarsal III tall, narrow and gently concave, against dorsal margin of cranial surface; sits dorsal to small, narrow triangular eminence. Facet for the mesocuneiform small to very small and narrow, immediately plantar and occasionally slightly medial to metatarsal III facet. Plantar tubercle squarish in medial view, rugose and thickened at the plantar margin with a slight medial deflection; articulates on its lateral surface with the medial plantar tubercle of the cuboid.
The ectocuneiform of P. viator sp. nov. differs from that of P. mamkurra in being slightly narrower, with a narrower, less concave, more plantarly extensive navicular facet and a deeper plantar tubercle; from P. otibandus in being slightly more transversely compressed and relatively taller, with the dorsal margin level (rather than rounded-triangular) and a more deeply concave entocuneiform facet; from C. kitcheneri in being larger, with a larger, less cranially deflected plantar tubercle, larger facet for the mesocuneiform, and the facet for the cuboid not abutting the facet for metatarsal III; from O. rufus in being larger, with the navicular facet extending much further plantarly, a smaller cranial eminence, narrower, deeper, less plantarly projected and less cranially deflected plantar tubercle, and a relatively larger metatarsal III facet; from M. fuliginosus in being larger, with a more plantarly extensive navicular facet, larger facet for the mesocuneiform, and a less medially deflected plantar tubercle; and from W. bicolor in being larger, with a less concave, more plantarly extensive navicular facet.
Mesocuneiform (Figs 75f & 77): small to very small, rectangular to oblong in medial view, quite elongate, transversely compressed and dorsoplantarly short; articulates with the mediocaudal surface of the proximal base of metatarsal III; entire caudal surface articulates with the cranial component of the dorsal surface of the entocuneiform. An extremely small cranial facet for metatarsal II is sometimes present beneath the facet for metatarsal III.
The mesocuneiform of P. viator sp. nov. differs from that of O. rufus and M. fuliginosus in being larger and more robust.
Entocuneiform (Figs 75e–f & 77): very elongate, transversely compressed and quite dorsoplantarly short; broadens and shortens caudally to a small, rounded and slightly dorsally tilted facet for the navicular; cranial section of the dorsal margin articulates with mesocuneiform. Facet for metatarsal II small, rounded and strongly dorsolaterally tilted; situated on dorsal component of cranial surface. The cranioplantar section of the lateral surface articulates with the lateral surface of the proximal plantar tubercle of metatarsal IV and with the medial margin of the proximal plantar sesamoid for metatarsals IV and V.
The entocuneiform of P. viator sp. nov. differs from that of O. rufus in being larger and more rectangular in medial view, with a taller caudal end and a slightly more laterally situated facet for metatarsal II; from M. fuliginosus in being larger and more rectangular in medial view, with a taller, less pointed cranial end and a slightly more laterally situated facet for metatarsal II; and from W. bicolor in being larger and more rectangular in medial view with a less pointed cranial end.
Proximal plantar sesamoid for metatarsals IV and V (Figs 75e–f & 77): broad and dorsoplantarly compressed, with a larger, rounded to oval medial section for articulation with the proximal plantar tubercle of metatarsal IV and a smaller, elongate, oval lateral projection for articulation with the plantomedial surface of the lateral plantar tuberosity of metatarsal V; dorsal surface of the proximomedial section articulates with the proximal plantar ridge on metatarsal IV. Lateral projection slightly plantarly deflected, creating a broad, shallow plantar groove across the medial section toward the entocuneiform for the m. flexor digitorum profundus IV + V.
The proximal plantar sesamoid of P. viator sp. nov. differs from that of O. rufus in being broader, with a larger facet for the plantar tubercle of metatarsal IV; from M. fuliginosus in being much larger and much broader, with the medial section more elongate, and the lateral projection relatively enlarged and projected to articulate with the plantar surface of the metatarsal V lateral plantar tuberosity, rather than abutting the medial surface of the shaft; and from W. bicolor in being larger and relatively slightly deeper.
Metatarsals II, III and phalanges (Figs 75e–f & 77): extremely gracile; III slightly longer than II, both shorter than metatarsal IV; both with shafts bowed distinctly laterally toward midpoint. Metatarsal III: proximal end tall and narrow, rapidly decreases in height to shaft; articulates proximally with mesocuneiform, ectocuneiform and metatarsals II and metatarsal IV. Metatarsal II: proximal end relatively small and very slightly plantarly deflected; articulates proximally with metatarsal III, entocuneiform and very slightly with mesocuneiform. Shafts transversely compressed proximally, become rounded in cross-section and gently taper distally. Distal ends small, bulbous and rounded.
Proximal phalanges for metatarsals II and III: very small and short; proximal ends thickened; shafts narrow to a waist before thickening to rounded, slightly bulbous distal ends. The distal end of phalanx for metatarsal II is not preserved.
The metatarsals II, II and phalanges of P. viator sp. nov. differ from those of P. otibandus in having metatarsals II and III slightly more gracile and shorter relative to length of metatarsal IV, with the shafts much more laterally bowed; from O. rufus and M. fuliginosus in having much shorter and more robust metatarsals, with a taller proximal end of metatarsal III, metatarsal II with a more laterally situated entocuneiform articulation, and a slightly longer proximalphalanx of metatarsal II; and from W. bicolor in being larger and slightly more robust, with the phalanges much shorter relative to the length of metatarsal IV.
Metatarsal IV (Figs 75e–f & 78a–f): short and fairly robust.Dorsal cuboid facet large and broad, with the lateral part flat to gently convex and the medial part flat to gently concave; dorsal margin flat to gently sinusoidal; medial part of dorsal facet continuous plantarly with the plantar cuboid facet, which abuts medial margin; plantar cuboid facet small, round to oval, generally flat and angled slightly to sharply dorsomedially, situated on the proximal surface of the thick, plantarly projected plantar tubercle, opposite the proximal plantar sesamoid facet; proximal cuboid fossa shallow and laterally situated; very small, occasionally indistinct facet for articulation with the plantolateral part of the ectocuneiform on the medial surface of the plantar tubercle, sometimes semicontinuous with the plantar cuboid facet. Proximal plantar sesamoid facet round to oval, flat to gently concave. Facet for metatarsal III indistinct, situated in elongate, shallow, rugose metatarsal III fossa on medial surface of proximal end, bordered dorsally by a thin ridge extending plantodistally from dorsomedial corner of dorsal cuboid facet. Dorsal facet for the ectocuneiform small and rounded to absent, abuts the dorsal section of the medial margin of dorsal cuboid facet. Facet for metatarsal V concave, tall and craniocaudally quite shallow; shape variable, but generally oblong with rounded dorsal and plantar parts; not extending plantarly onto the lateral surface of the plantar tubercle.
Plantar ridge broad, rounded and rugose, extends distally with a slight lateral deflection from the base of the plantar tubercle, merges into the plantar surface of the shaft at its midpoint; bordered medially by the fossa for metatarsal III and laterally by the fossa for metatarsal V. Shaft broadens gently, particularly on the lateral margin, to a broad distal end; lateral margin appears more concave proximally due to the projected lateral part of the base; taller proximally and quite low distally; proximal part of the dorsal surface of the shaft generally slightly laterally tilted, becoming flat to gently rounded distally. Distal end broad; fossae for the collateral ligaments circular and quite deep; keel narrow and subequally to slightly more plantarly projected than the lateral and medial crests.
The metatarsal IV of P. viator sp. nov. differs from that of P. anak in being generally slightly shorter; from P. mamkurra sp. nov. in being shorter, generally with a smaller plantar cuboid facet; from P. tumbuna in being larger; from P. dawsonae sp. nov. in being shorter and more gracile; from P. otibandus in being larger and more gracile, with a more raised plantar ridge and continuous dorsal and plantar cuboid facets; from P. snewini in being slightly larger and more elongate, with a relatively longer plantar ridge, continuous dorsal and plantar cuboid facets, and a more plantolaterally situated proximal cuboid fossa; from C. kitcheneri in being larger and broader, with a more plantarly projected proximal plantar tubercle and a larger facet for the proximal plantar sesamoid; from O. rufus and M. fuliginosus in being shorter, broader, much more robust and less arched in lateral view, with a larger facet for metatarsal V, lower plantar ridge, and a larger, more plantarly projected proximal plantar tubercle; and from W. bicolor in being larger, relatively broader and more robust, with a more plantarly projected proximal plantar tubercle.
Metatarsal V (Fig. 78g –k): quite robust and curved slightly laterally toward distal end; tall and highly transversely compressed, particularly proximally, giving the proximal end a distinct bulged appearance in lateral view; length to distal end width index ~4.4–5.4; slightly arched in lateral view. Proximolateral process quite proximodistally short and blunt, quite tall, slightly laterally deflected, transversely compressed, and rugose. Cuboid facet oval to rounded, gently concave, extends from the dorsal surface and medial surface of the base of the proximolateral process onto the proximal base of the medial plantar tubercle. Facet for metatarsal IV quite large, convex, variably oval, proximodorsally adjacent to or abutting the cuboid facet and extending medially from dorsal surface to above midpoint of medial surface. Lateral plantar tuberosity very elongate and rugose, distinctly plantarly projected, merges distally into the plantar shaft; bounded on the medial margin by a narrow channel separating it from the medial plantar tubercle. Medial plantar tubercle small, rounded and plantomedially projected; considerably less plantarly projected than lateral tuberosity. Shaft decreases in height and broadens to the distal end. Distal end quite tall; medial and lateral facets subequal in width.
The metatarsal V of P. viator sp. nov. differs from those of other species of Protemnodon in being more transversely compressed. It further differs from that of P. anak in being generally slightly taller and less elongate, with a narrower, less concave cuboid facet (Fig. 78k), less proximally projected medial plantar tubercle, and a narrower and taller distal end; from P. mamkurra sp. nov. in being taller, particularly proximally, and generally less elongate, with a narrower, more dorsally situated cuboid facet; from P. tumbuna in being more elongate and gracile, with a larger, more elongate lateral plantar tuberosity, more dorsally situated metatarsal IV facet, and a taller, narrower distal end with a more pointed keel; from P. dawsonae sp. nov. in being taller, particularly proximally due to the more raised lateral plantar tuberosity, and less elongate, with a narrower, more dorsally situated cuboid facet, a taller, less elongate proximolateral process, and a less proximally projected medial plantar tubercle; from P. otibandus in being larger and more elongate, with a narrower and more dorsally situated cuboid facet and the metatarsal IV facet less extensive medially and more distinct from the cuboid facet; from C. kitcheneri in being slightly larger, more robust and taller, particularly proximally, due to the larger lateral plantar tuberosity, and lacking the slight kink of the arch of the shaft immediately proximal to the midpoint in lateral view, with a taller, more rounded proximolateral process and a more rounded, slightly more dorsally tilted facet for the cuboid; from O. rufus and M. fuliginosus in being far shorter, broader, less arched and less transversely compressed, with a longer proximolateral process and a larger medial plantar tubercle; and from W. bicolor in being larger, more robust and taller, particularly proximally, with a larger proximolateral process and narrower, rounder and more concave cuboid facet and metatarsal IV facet.
Pedal phalanges (Figs 79 & 80): proximal phalanx IV: dorsoplantarly compressed and quite elongate, with a narrow waist, and broad proximal and distal ends. Proximal end low and domed, with the proximal plantar tubercles very low, elongate and rugose; proximal articular facet broad and concave with rounded dorsal margin. The height of the shaft gently decreases to the distal end. Distal end trapezoidal in distal view, with the fossae for the collateral ligaments extremely shallow to absent. Trochlea very gently concave. Middle phalanx IV: short, broad and very dorsoplantarly compressed, with a very slight waist. Proximal end broad, with the lateral and plantar margins thickened and rugose. Proximal plantar tubercles low and gently rugose, with rugose surface extending onto the lateral and medial surfaces of the proximal shaft and extending further distally in older individuals. Proximal articular surface broad, very low and concave. Distal end with very shallow fossae for the collateral ligaments. Trochlea very slightly concave dorsally and deepens plantarly; articular facet is not extensive proximoplantarly. Distal phalanx IV: quite tall and robust. Proximal articular facet concave and roughly pentagonal; proximal plantar tubercle large, rugose and oval in plantar view. Shaft with a slightly rounded triangular peak in cross-section, curves distinctly plantarly in lateral view and narrows steadily to a rounded point in dorsal view.
Proximal phalanx V: proximal end slightly broader than tall, with large, rounded and rugose plantar tubercles; proximal articular surface round, concave and medially displaced in proximal view. Height decreases distally, with a slight waist on the shaft in dorsal view. Distal end with fossae for the collateral ligaments absent; trochlea gently concave; articular surface not very extensive dorsally. Middle phalanx V: very short, broad, dorsoplantarly compressed and decreasing in height distally; distinctly asymmetrical, with the proximal and distal surfaces medially and laterally tilted respectively.Proximal end with low, rounded plantar tubercles; proximal articular surface gently concave, dorsally domed and tilted dorsomedially. Shaft extremely short with no waist. Distal end with the fossae for the collateral ligaments very shallow and dorsally displaced; trochlea gently concave and articular surface dorsoplantarly quite short. Distal phalanx V: elongate and distinctly asymmetrical; dorsal peak of the shaft and proximal end medially displaced (Fig. 80i) and shaft very slightly medially curved. Proximal end with a small, rounded projection on the medial and lateral margins; fossae for the collateral ligaments small and deep; plantar tubercle small and rounded in plantar view; proximal articular surface concave and rounded-rectangular. Shaft with a rounded triangular dorsal peak and a convex plantar margin in cross-section, smoothly plantarly curved distally, narrows rapidly at the distal end to a rounded point.
The pedal phalanges of P. viator sp. nov. differ from those of P. anak in being more elongate, with proximal phalanx IV having a more distinct waist, middle phalanx IV having a relatively narrower, less dorsally tilted proximal end and a less proximoplantarly extensive distal articular surface, distal phalanx IV having a more pointed dorsal peak, and distal phalanx V having a more pointed, more medially displaced dorsal peak; from P. mamkurra sp. nov. in being generally slightly shorter, with shallower collateral fossae on the proximal and middle phalanges, proximal phalanges with a narrower waist, a relatively broader middle phalanx IV with relatively larger, more distally extensive plantar tubercles, distal phalanx IV with a more triangular dorsal peak and lacking distinct triangular divots on the medial and lateral margins of the proximal articular surface, and distal phalanx V with a more pointed, more medially displaced dorsal peak; from P. dawsonae sp. nov. in having more gracile proximal phalanx IV with a narrower waist and broader distal end relative to the proximal end; from P. otibandus in being larger, with a more elongate proximal phalanx IV having a narrower waist, distal phalanx IV with a more triangular proximal surface, more pointed dorsal peak, and a less dorsoplantarly compressed, more plantarly curved shaft, proximal phalanx V with a more concave proximal articular surface, less laterally deflected shaft, and a broader trochlea, a more elongate middle phalanx V with a more medially tilted proximal surface, and distal phalanx V with a more pointed dorsal peak; from P. snewini in being larger, with middle phalanx IV having a narrower distal articular surface relative to the distal width and a smaller distal end relative to proximal end in lateral view, and distal phalanx IV having a longer and less plantarly projected plantar tubercle; from C. kitcheneri in being broader, more robust and more dorsoplantarly compressed, particularly the middle phalanges, with a broader, slightly shallower trochleae, middle phalanx IV with a less caudoplantarly extensive distal articular surface and distal phalanges with more rounded dorsal peaks; from O. rufus and M. fuliginosus in being broader and more robust, with the phalanges V slightly larger relative to the phalanges IV and the distal phalanges having a slightly less angular, more rounded dorsal peak and a more plantarly curved shaft; and from W. bicolor in being larger and more robust, with a narrower waist on proximal phalanx IV.
description: Published as part of Kerr, Isaac A. R., Camens, Aaron B., Van Zoelen, Jacob D., Worthy, Trevor H. & Prideaux, Gavin J., 2024, Systematics and palaeobiology of kangaroos of the late Cenozoic genus Protemnodon (Marsupialia, Macropodidae), pp. 1-261 in Megataxa 11 (1) on pages 100-140, DOI: 10.11646/megataxa.11.1.1, http://zenodo.org/record/10993768