Protemnodon otibandus Plane, 1967

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), Megataxa 11 (1), pp. 1-261 : 169-187

Protemnodon otibandus Plane, 1967

Protemnodon otibandus Plane, 1967 : Bull. Bur. Min. Res., Geo. & Geophys., Aus., 86, pp. 26–44, figs 5–10. See also: Mahoney& Ride (1975), p. 23.

Protemnodon chinchillaensis Bartholomai, 1973 : Mem. Qld. Mus., 16, pp. 347–354, pl. 20, 21, 23. See also Flannery & Archer (1984), pp. 375–376, figs A & B.

Protemnodon anak Owen ; De Vis (1895) (partim), pp. 104–109. Not P. anak, Owen, 1874 .

Protemnodon devisi Bartholomai : Tedford et al. (1992), p. 187. Not P. devisi, Bartholomai, 1973 .

Protemnodon Owen sp. indet.; Tedford et al. (1992), pp. 186–187.

Holotype: CPC 6771 : near-complete R dentary preserving i1 & p3–m4; posteromedial fracture along margin of pterygoid fossa with pterygoid process not preserved. Figured Plane (1967), figs 5 & 6. Reassociated here are the holotype, CPC 6771, and specimen UCMP 69895 , a semi-complete L dentary preserving the base of the i1 and p3–m4, based on extreme similarity in dimensions, degree of molar wear, morphology, shape of mandibular symphyseal plates and preservation. UCMP 69895 was collected by the same expedition from the same locality as the holotype.

Type locality:

‘Watut 1’, UCMP V6234, west bank of Upper Watut River (7°13’ S, 146°32’ E), Otibanda Fm., Morobe Province, Papua New Guinea. The type section contains fossiliferous sandstone and mudstone with conglomerate and intercalated pyroclastic rocks. Potassium–Argon dating of a pyroclastic rock sample, taken from an outcrop of the Otibanda Fm. approximately 250 m downstream from the type locality, gave an age of 2.9 ± 0.4 Ma ( Hoch & Holm 1986), placing it in the late Pliocene.

Paratype (s):

Premaxilla fragments: UCMP 69832. Partial maxilla: UCMP 69851–69854, UCMP 69857. I1: UCMP 69790– 69800, UCMP 69877, UCMP 69859. I2: UCMP 63631, UCMP 69803, UCMP 69804, UCMP 69806, UCMP 69825, UCMP 69826. I3: UCMP 69827–69831. DP2: UCMP 69833. P3: UCMP 69834–69839, UCMP 69863, UCMP 69864. M1: UCMP 69840–69842. M3: UCMP 69843, UCMP 69844. M4: UCMP 69847–69849. Dentary fragments: UCMP 69896, UCMP 69897, UCMP 69981, UCMP 69986, UCMP 69987, UCMP 69991, UCMP 69899, UCMP 69900. Juvenile dentary: CPC 6772. i1: UCMP 69860, UCMP 69871–69878. p3: UCMP 69861, UCMP 69863, UCMP 69864, UCMP 69879. m1: UCMP 69865. m3: UCMP 69870. m4: UCMP 69898.

Referred specimens:

Papua New Guinea

Site 2, Watut River: UCMP 45345 vertebral fragment, R calcaneus, talar fragment, metatarsals IV and V, distal pedal phalanx IV, and proximal & middle pedal phalanges V.

Sunshine 3, Watut River: UCMP 71414 partial R talus and metatarsal IV, partial LR metatarsals V and proximal pedal phalanges IV, and middle pedal phalanx IV.

Sunshine General, Watut River: UCMP 45344 LR femoral fragments.

Watut 1, Watut River: UCMP 70036 R i1; UCMP 70045 clavicle; UCMP 70059 partial R humerus, ulna, radius and articulated manus; UCMP 70054 partial R radius; UCMP 70065 partial L femur; UCMP 70066 partial L femur; UCMP 70038, 70039, 70584 and 70585 femoral fragments, partial LR tibiae, L and partial R calcaneus, L cuboid, LR metatarsals IV and V, and proximal and distal pedal phalanges IV; UCMP 70078 L cuboid; UCMP 70006 partial R metatarsal IV; UCMP 70007 partial R metatarsal IV.

Woodard 2, Watut River: UCMP 45246 partial juvenile R premaxilla, partial L maxilla, partial R maxilla, R P3, and partial mandible; UCMP 45248 partial R maxilla; UCMP 45250 R talus; UCMP 45253 L cuboid.

Woodard 3/Site 3,Watut River: UCMP 45247 L calcaneus, R talus, articulated R cuboid, ectocuneiform and metatarsals II, III and IV, R metatarsal V, proximal, middle and distal pedal phalanges IV, and middle and distal pedal phalanges V.

Woodard 4, Watut River: UCMP 45244 partial premaxilla, maxillae and L dentary, and tibial fragments.

Northwest bank of Kikori River, Gulf Province: AM F134486 pelvic fragment with acetabulum.

South Australia

Stirton Quarry (V5772), Lake Kanunka: UCMP 56894 L dentary; UCMP 156893 R calcaneus.

Site 6 (27° 51.327’ S, 137° 53.385’ E), Toolapinna Waterhole, Warburton River: SAMA P50566 R dentary.

Toolapinna Waterhole, Warburton River: SAMA P25504 partial L maxilla.

Lawson–Daily Quarry, Lake Palankarinna: UCMP 57195 L tibia.

Queensland

Chinchilla, Darling Downs (site unknown): QM F4719 L maxilla; QM F5239 partial juvenile L maxilla; QM F5246 partial R dentary.

New South Wales

Bow LF, Hunter Valley: AM F59530 partial L maxilla; AM F59533 partial L maxilla.

Victoria

Nowa Nowa Arm, Lake Tyers: NMV P26893 partial R maxilla.

Revised specific diagnosis:

Protemnodon otibandus is distinguished from all other species of Protemnodon by one unique skeletal characteristic and by a combination of other dental and skeletal characteristics. The pes of P. otibandus differs from all other species of Protemnodon in having a calcaneus with a slightly medially offset head relative to the calcaneal tuberosity. In P. tumbuna this condition is more extreme, with the head more strongly medially displaced; in all other species of Protemnodon the head of the calcaneus is not medially displaced.

Protemnodon otibandus is most similar in dentary morphology to P. anak , P. dawsonae sp. nov. and P. tumbuna . It differs from that of P. anak and P. dawsonae sp. nov. in its less robust anterior dentary, particularly around the i1. It differs further from P. anak in its more dorsally deflected diastema; and from P. tumbuna in having a more anterodorsally situated mental foramen.

Protemnodon otibandus is most similar in dental morphology to P. snewini and P. tumbuna . The dentition differs from P. snewini in having: P3 with a broader posterior relative to the anterior cusp and a higher lingual crest; relatively broader upper molars with a less anteriorly prominent precingulum, a more raised, more distinct postparacrista, and a urocrista; and more robust, less lanceolate i1. The dentition differs from that of P. tumbuna in having: P3 with more raised, more distinct buccal ridgelets; less rounded molars; and i1 with a thinner, more raised ventrolingual crest.

Protemnodon otibandus is most similar in aspects of skeletal morphology to P. tumbuna and P. snewini . The hindlimb differs from P. tumbuna in having: a femur with a less elongate and more proximally situated quadratus tubercle; and a narrower tibia with a thinner, more raised proximolateral crest and a less distally extensive cnemial crest with a more defined peak. The pes further differs from that of P. tumbuna in having: a calcaneus with a more planar plantar surface with less flaring of the medial margin and a smaller, shallower fossa cranial to the lateral talar facet; and more transversely compressed metatarsal V with dorsoplantarly shorter proximolateral process, longer metatarsal IV facet and larger medial plantar tubercle. The hindlimb differs from that of P. snewini in having a tibia with a larger, broader proximal fibular facet. The pes differs from that of P. snewini in having: talus with a deeper trochlea and a deeper concavity between the posterior plantar tubercle and the talar head; cuboid with a less dorsomedially flared dorsomedial section, a much smaller talar facet, and a larger, more plantomedially projected medial plantar tubercle; metatarsal IV with a dorsoplantarly shorter, more plantarly situated proximal cuboid fossa; and distal phalanx IV with a more rounded dorsal peak.

Etymology:

In reference to the geological formation of the type locality, the Otibanda Formation.

Description and comparisons:

For craniodental description, see the original description by Plane (1967, pp. 28–39). For comparative purposes, the cranium, dentary and dentition are figured below ( Figs 98 & 99 ).

Pectoral girdle and forelimb

Clavicle ( Fig. 100a–c ): craniocaudally compressed in the middle section and at the acromial articular end, becomes rounded in cross-section toward the sternal articular end; curves gently posteriorly towards both ends in caudal view, to be gently convex anteriorly; steadily increases in depth medially to the slightly thickened, smoothly ventrally curved acromial articular end, and forms a blunted point. Sternal articular end thickened, rounded in medial view; epiphysis not preserved, but the medial surface has a convex posterior part and a small, deep fossa in its centre.

The clavicle of P. otibandus differs from that of all compared species in being more craniocaudally compressed. It further differs from that of P. mamkurra sp. nov. in being slightly less robust, with a relatively slightly smaller acromial articular end; from C. kitcheneri in being more curved, with a relatively larger acromial articular end; from O. rufus and M. fuliginosus in having a slightly more caudally curved and less posteriorly curved acromial end, and a much less anteroposteriorly concave sternal articular surface; and from W. bicolor in being larger and deeper, with a more ventrally curved acromial end with a more pointed tip, and the sternal end not strongly anteroposteriorly compressed.

Humerus ( Fig. 100d–e ): only one distal fragment known; distal end broad. Lateral supracondylar ridge quite thick and convex cranially at distal end; lateral epicondyle not preserved. Capitulum and ulnar facet broad, weakly projected and laterally situated, close to the lateral epicondyle; combined width is roughly three-quarters of the epicondylar width; capitulum smoothly convex; ulnar facet with the medial margin relatively straight and unbevelled; trochlea wide and quite shallow. Olecranon fossa broad and deep; radial fossa quite large and deep compared to the coronoid fossa; coronoid fossa partially preserved, appears shallow, broad and proximodistally short. Medial supracondylar bridge partially preserved, appears broad, and thin craniocaudally; supracondylar foramen appears large and quite flattened craniocaudally. Medial epicondyle large, rounded, rugose and very slightly distally projected.

The humerus of P. otibandus does not differ from that of P. tumbuna . It differs from P. anak in being smaller, with a smaller capitulum and ulnar facet, a narrower medial supracondylar bridge, shallower trochlea, and a more curved, less distinct and less distally projected medial margin of the ulnar facet; from P. mamkurra sp. nov. and P. viator sp. nov. in being smaller, with a less projected capitulum and ulnar facet, and less bevelled medial margin of the ulnar facet; from C. kitcheneri in having a broader medial supracondylar bridge; from O. rufus in having a broader distal end, broader distal part of the lateral supracondylar ridge, and a relatively larger ulnar facet; from M. fuliginosus and W. bicolor in having a broader distal end, broader distal part of the lateral supracondylar ridge, and a shallower trochlea; and additionally differs from W. bicolor in being larger.

Ulna ( Fig. 101a–i ): moderately large, deep, transversely compressed, curved cranially in lateral view and gently medially curved in cranial view.Olecranon quite elongate, transversely compressed and tapers in height to a blunt, slightly caudally deflected in lateral view, with a squared distal end. Proximal section of the lateral surface of the ulna is flat; proximomedial flexor fossa smoothly, deeply concave. Facet for the humeral articulation is quite broad, with no visible trochlear notch; medial part deeply concave, more elongate and situated more cranially than the lateral part; lateral part relatively shallow, smoothly concave and tilted and projected laterally, with the lateral margin abraded in the sole known specimen; anconeal process low relative to the coronoid process, with an obtuse, slightly rounded mesial angle; coronoid process tall, quite narrow, and smoothly rounded in posterior view; merges gently into the shaft distally ( Fig. 101a ). Radial facet mostly abraded, but appears roughly semicircular and abuts the lateral three-quarters of the anterior margin of the lateral part of anconeal facet. Ulnar tuberosity low, narrow, quite elongate, slightly thickened and rugose. Proximal part of the shaft is slightly crushed; interpreted as having been transversely compressed and deep; caudal margin straight beneath the olecranon and the humeral facet, curves gently cranially past the humeral facet, and straightens distally; midpoint of the cranial surface of the shaft has thin ridge tilted laterally. Distal end has a cone-shaped base, smoothly narrows to a projected, globular styloid process.

The ulna of P. otibandus does not differ from that of P. tumbuna . It differs from P. anak in being smaller and lacking a large caudomedial eminence on the olecranon, with a less deep proximal shaft and a more concave medial surface beneath the humeral facet; from P. mamkurra sp. nov. in being more gracile and more transversely compressed, with a relatively longer olecranon; from P. viator sp. nov. in being generally smaller, deeper and more dorsoventrally compressed, with relatively longer olecranon, more deeply concave humeral facet, narrower coronoid process with a gentler slope anteriorly into the shaft (rather than meeting the shaft at almost a right angle), and a shallower proximomedial flexor fossa; from C. kitcheneri in being generally larger, and deeper and more transversely compressed proximally, with a less cranially deflected olecranon, taller, less medially flared coronoid process, and a lower, more proximally situated cranial ridge on the shaft; from O. rufus in being more robust, and deeper and more transversely compressed proximally, with a less cranially deflected olecranon, less medially flared anconeal process, and a taller coronoid process; from M. fuliginosus in being larger and more robust, and deeper and more transversely compressed proximally, with a less tall olecranon, less medially flared anconeal process, and a taller coronoid process; and from W. bicolor in being larger, with a relatively longer, cranially undeflected and unprojected olecranon, lower, narrower anconeal process, and a lower, less medially flared coronoid process.

Radius ( Fig. 100f–g ): elongate, with a gently arched shaft curving mediocaudally past the radial tubercle. Radial head broad, oval and smoothly concave. Radial neck narrows to the radial tubercule. Radial tubercule rugose, oval and smoothly projected. Shaft cross-section oval immediately distal to the radial tubercle, quickly transitions to strongly craniomedially-caudolaterally compressed by the midpoint; gently broadens distally. Cranial ridge short, quite thin and located immediately proximal to the midpoint of the shaft; caudal ridge relatively thinner and more raised on the caudomedial to caudal surface. Distal end large and craniocaudally compressed with a small tubercle on the cranial surface; scaphoidal facet broad, slightly caudally tilted and gently concave, located caudal to a low, shallow fossa across the cranial section; styloid process broad, craniocaudally compressed and tapering to a rounded tip. Ulnar notch broad, very shallowly concave and elongate, slowly tapers proximally along the caudolateral surface.

The radius of P. otibandus cannot be not differentiated from that of P. tumbuna . It differs from P. anak in being generally smaller, with the distal end more craniocaudally compressed; from P. mamkurra sp. nov. in having a less raised cranial ridge and a shallower proximal shaft; from P. viator in being shorter, with a more raised caudal ridge and a less proximally situated cranial ridge; from C. kitcheneri in having a more raised cranial ridge, less elongate caudal ridge, and a caudally (rather than cranially) tilted scaphoidal facet; from O. rufus in being more robust, with a larger radial tubercle, and more raised caudal ridge; from M. fuliginosus in being more robust, with a relatively larger proximal epiphysis and a more raised caudal ridge; and from W. bicolor in being larger.

Manus

Scaphoid ( Fig. 101e–g, i ): broad, roughly semicircular in dorsal view with a broadly convex proximal surface; dorsopalmarly shortens medial to the midpoint. Radial facet broad and strongly, smoothly convex, extends from posteriorly adjacent to the triquetral facet, across the posterior surface, to the posterior margin of the palmar process; becomes gently concave medially due to a low, rounded eminence on the medial margin and a broad, raised, anteroposteriorly short crest located slightly medial of the centre of the dorsal surface, for articulation with the styloid process of radius. Palmar process broad, tapers in dorsal view to a rounded tip, slightly anteroposteriorly compressed and curves distinctly palmarly toward the tip. Facet for the hamatum large, covers anterolateral surface. Facet for the capitatum slightly broader than the hamatal facet; covers the centre of the anterior surface. Facet for the trapezoid palmarly convex and dorsally concave beneath anterior of dorsal crest, abuts capitatum facet on anterodorsal surface of palmar process. Facet for the trapezium tall, rounded and convex, wraps around the anteromedial surface of the palmar process.

The scaphoid of P. otibandus differs from that of P. mamkurra sp. nov. in having a slightly more palmarly curved and anteriorly deflected palmar process, with a shallower fossa on the medial part of the palmar surface; from P. viator sp. nov. in being smaller, with a raised dorsal ridge, a taller, more convex radial facet, larger medial eminence, and a less dorsopalmarly compressed palmar process; from C. kitcheneri in being broader, with a raised dorsal ridge and a broader, more anteropalmarly deflected palmar process; from O. rufus in being broader, with a larger palmomedial fossa and a more dorsopalmarly compressed palmar process; from M. fuliginosus in being relatively broader, with a broader, more smoothly convex radial facet and a less deep, more palmarly curved palmar process; and from W. bicolor in being much larger, with a low, rounded eminence present on the medial margin of the radial facet.

Pisiform ( Fig. 101e–i ): quite elongate and distinctly dorsopalmarly flattened; large, squared proximal end constricts to a narrow waist and flares anteroposteriorly to the thickened, rounded distal end. The posteromedial facet for the styloid process of the ulna is small, located on the posteromedial margin.

The pisiform of P. otibandus differs from that of P. viator in being smaller, with a more dorsopalmarly compressed proximal end and a much smaller proximal ulnar facet; from C. kitcheneri in being larger relative to the other carpals and more elongate, with a narrower waist and a more dorsopalmarly compressed distal end; from O. rufus and M. fuliginosus in being more elongate, with a narrower waist and a more dorsopalmarly compressed base lacking an anterodorsal tubercle; and from W. bicolor in being larger and more robust, with a relatively larger, deeper distal end.

Triquetrum ( Fig. 101e–i ): broad and blocky; dorsal surface gently convex with small ridges along the anterior and posterior margins.The palmar surface forms a rounded point at the posterior margin. Facet for the styloid process of the ulna rounded and concave. Facet for the pisiform long and dorsopalmarly short. Facet for the hamatum large, occupying most of the anterior surface.

The triquetrum of P. otibandus differs from that of P. mamkurra sp. nov. in having a flatter dorsal surface and a slightly smaller pisiform facet; from C. kitcheneri in being larger relative to the other carpals, with a broader and flatter dorsal surface and a slightly more laterally and less palmarly situated facet for the pisiform; from O. rufus in having flatter dorsal surface, with a smaller and more palmarly situated facet for the pisiform; from M. fuliginosus in being deeper, with a flatter dorsal surface; and from W. bicolor in being absolutely larger, larger relative to the size of the pisiform, and more robust.

Hamatum ( Fig. 101e–h ): quite deep and blocky, with a narrow, blunted palmar process projecting palmomedially from the posteromedial edge; dorsal surface is gently convex; a small, rounded eminence projects posteromedially. Facet for the triquetrum quite broad and mostly posterior facing, occupies the lateral part of the posterior surface except for on the palmar process; a small posterior part of the facet extends onto the posteromedial process of the hamatum, with the medial margin distinct and separate from the facet for the scaphoid. Facet for the scaphoid small and concave, on posteromedial surface. Facet for the capitatum small, narrow and facing anteromedially, with slight dorsal lip. Facet for metacarpal III narrow and faces anteromedially. Facet for metacarpal IV broad, narrows palmarly onto the medial base of the palmar process. Facet for metacarpal V quite large and anterolaterally facing, covers the majority of the anterior surface of the palmar process, with a rounded palmar lip.

The hamatum of P. otibandus differs from that of P. mamkurra sp. nov. in being smaller and deeper, with the triquetral facet distinctly separate from the scaphoidal facet, and a smaller, posteropalmarly projected palmar process; from P. viator sp. nov. in being smaller, with a smaller triquetral facet that is less deeply inset, less extensive medially, and distinctly separate from the scaphoidal facet; from C. kitcheneri in having a broader triquetral facet and larger facets for the capitatum and metacarpal III; from O. rufus in having a slightly more palmarly situated triquetral facet and a less anteriorly deflected and extensive palmar process; from M. fuliginosus in being slightly deeper, with a more laterally situated triquetral facet relative to the scaphoidal facet, and a less palmarly projected, much less anteriorly curved palmar process; and from W. bicolor in being larger and deeper, with the scaphoidal and triquetral facets distinct rather than abutting, and a broader, less palmarly projected palmar process.

Capitatum ( Fig. 101e–g ): tall and blocky, with a flat dorsal surface and a rugose, slightly concave, roughly triangular palmar surface. Posteropalmar process very slight to absent. Facet for the scaphoid located on the medial component of the posterior surface. Facet for the triquetrum slightly larger than the scaphoidal facet, situated on the posterolateral surface. Facet for metacarpal III broad, with semi-distinct anterior and anterolateral components; a small, dorsally opening mesial fossa on a slight corner separates the slightly broader anterolateral facet from the smaller anterior facet. Facet for the posterolateral articulation of metacarpal II small, quite tall and narrow, medially abuts the anterior section of the facet for metacarpal III. Facet for the trapezoid tall, narrow and gently concave, anteromedially abuts the scaphoidal facet.

The capitatum of P. otibandus differs from that of P. mamkurra sp. nov. and P. viator sp. nov. in being smaller and lacking a blunt posteropalmar process; from C. kitcheneri in being generally squarer and less rounded, lacking a posteropalmar process and in having the dorsal surface flat instead of convex; from O. rufus in being slightly anteroposteriorly deeper; from M. fuliginosus in being squarer in dorsal view, with a more medially and less anteriorly facing facet for metacarpal II and a less medially projected facet for the trapezoid; and from W. bicolor in being larger, deeper, and squarer in dorsal view, with a larger, deeper hamatal facet.

Metacarpals ( Fig. 101e–i ): short and quite robust, with metacarpals II–IV relatively more elongate; each shaft narrows to a distinct waist; tall proximally, becoming dorsopalmarly compressed distally, particularly II–IV; all with large, broad and rounded distal keels. Metacarpal I: shortest, with a tall, narrow facet for the trapezium laterally situated on the proximal surface; a large, blunt tubercle on the palmomedial surface of the proximal end projects medially; metacarpals I and V have distinctly asymmetrical distal ends, skewed mesially. Metacarpal II: substantially shorter than III and IV, with the lateral surface of the proximal end articulating against the anterolateral surface of the capitatum and the lateral surface of the proximal end of metacarpal III; distal end has a distinctly enlarged lateral section. Metacarpal III: longest, with the proximal end separated into a longer, medially deflected medial process and a short, laterally deflected lateral process. Metacarpal IV: has a broad proximal facet for articulation with the capitatum, tilted dorsally and slightly medially, with the dorsal margin distinctly concave in dorsal view. Metacarpal V: proximal end has a large, blunt tubercle on the palmolateral surface that is strongly projected laterally; shaft curves slightly palmarly.

The metacarpals of P. otibandus differ from those of P. anak in being slightly smaller; from P. mamkurra sp. nov. in being smaller and slightly more gracile; from P. viator sp. nov. in being smaller and more robust; from C. kitcheneri in being more elongate, with shafts with more pronounced waists, generally broader proximal articular surfaces, flatter and less convex distal articular surfaces and generally squarer distal ends; from O. rufus in being relatively slightly broader; from M. fuliginosus in being slightly more elongate; and from W. bicolor in being much larger.

Manual phalanges ( Fig. 101e–i ): short, broad, dorsopalmarly compressed and quite symmetrical, particularly proximal and middle phalanges; proximal phalanx II more gracile than other proximal phalanges; proximal phalanges slightly shorter than the corresponding distal phalanges. Proximal phalanges: palmar tubercles raised, rounded and proximally projected; trochlea moderately shallow and quite narrow. Middle phalanges: very short, broad and dorsopalmarly compressed; shafts have very slight waists. Distal phalanges: quite long, with the palmar tubercle large and palmodistally projected ( Fig. 101h ),and the shaft palmarly curved,slightly dorsopalmarly compressed and smoothly rounded on the dorsal surface.

The manual phalanges of P.otibandus differ from those of P. anak in being smaller, with more palmarly curved distal phalanges; from P. mamkurra sp. nov. in having less dorsopalmar compression, longer, narrower proximal and middle shafts, and more palmarly curved distal phalangeal shafts; from P. viator sp. nov. in being smaller and more gracile, with less dorsopalmarly compressed distal phalanges with more projected palmar tubercles; from C. kitcheneri in being broader, far more dorsopalmarly compressed, particularly the middle and distal phalanges, and significantly shorter relative to the metacarpals, with broader, less V-shaped trochleae, more dorsally tilted proximal surfaces of proximal phalanges, and dorsally rounded distal phalanges with less palmar curvature of the shaft; from O. rufus in being slightly broader, with proximal phalanges having a broader distal end relative to the proximal end, and distal phalanges having longer, more dorsopalmarly compressed and palmarly curved shafts; from M. fuliginosus in having the proximal and middle phalanges with slightly more dorsally tilted proximal surfaces and less V-shaped trochleae, and more dorsopalmarly compressed distal phalanges with palmarly curved shafts; and from W. bicolor in being larger.

Hindlimb

Femur ( Fig. 102a–e ): mid-sized and gracile. Head large, very broad, rounded, hemispherical, dorsomedially projected and situated quite close to the medial base of the greater trochanter with the thick epiphyseal surface continuous between the two; rotated distally such that the articular surface faces slightly medially; the base of the trochanter is deep. Proximal end fairly broad, with the dorsal surface convex in the mesial third. Greater trochanter large, blunt, transversely compressed and slightly medially deflected; thickened on the dorsal surface of the base. Greater trochanteric ridge and trochanteric fossa poorly preserved in available specimens; appear elongate in UCMP 45344, with a deep fossa in UCMP 70065. Intertrochanteric crest quite thick, moderately raised and curves distally with slight medial deflection; ventromedially orientated in cross-section; abuts the small, rugose lesser trochanter. Lesser trochanteric ridge thick, raised, distally elongate and ventromedially projected.

Shaft straight, round in cross-section, with the caudal surface flattened and broadened distally for the insertion of the ischiatic portion of the mm. adductores. The quadratus tubercule is situated around the midpoint of the ventral surface of the shaft; raised and oval. Distolateral fossa for the m. flexor digitorum superficialis elongate, shallow and lateral-facing. Distal end tall and robust. Lateral trochlear crest broad and rounded relative to the medial crest, but subequal in height. Trochlea deep and approaches Vshaped ( Fig. 102d ). Intercondylar fossa large and deep, extends dorsodistally to just past the midpoint of the distal surface. Condyles broad, subequal in width and gently convex ventrally. Lateral epicondyle tall, rounded and laterally very projected; lateral gastrocnemial fossa deep and rounded. Fibular facet quite broad, laterally projected and slightly caudally deflected. Medial epicondyle has a slight lateral projection of the ventral component; medial gastrocnemial fossa broad and very slightly concave.

The femur of P. otibandus differs from that of P. anak in being smaller, with a deeper, narrower trochlea and a narrower, more raised medial trochlear crest; from P. mamkurra sp. nov. in being smaller, with a narrower, deeper trochlea, and a narrower medial trochlear crest and medial condyle; from P. viator sp. nov. in being smaller, with a less medially projected lesser trochanter, and a narrower medial trochlear crest and medial condyle; from P. tumbuna in having a less elongate, more proximally situated quadratus tubercle; from C. kitcheneri in having a more elongate, medially deflected and transversely compressed greater trochanter, deeper trochlea, trochlear crests subequal in height, and a less elongate and more proximally situated lateral gastrocnemial fossa; from O. rufus in having a more medially deflected greater trochanter, head positioned closer to the base of the greater trochanter, more distally extensive lesser trochanteric ridge, relatively broader distal condyles, trochlear crests subequal in height, more laterally projected lateral epicondyle, and a more proximally situated lateral gastrocnemial fossa; from M. fuliginosus in being generally larger, with a more elongate, more transversely compressed greater trochanter, more distally extensive lesser trochanteric ridge, relatively broader distal condyles, deeper trochlea, more laterally projected lateral epicondyle, and a more proximally situated lateral gastrocnemial fossa; and from W. bicolor in being larger, with a relatively larger, more dorsally projected and more medially tilted head, more rounded greater trochanter, more distally extensive lesser trochanteric crest, more distally situated quadratus tubercle, broader, less raised trochlear crests, slightly deeper trochlea, larger fibular facet on the lateral condyle, and a more laterally projected lateral epicondyle.

Tibia ( Fig. 102f–k ): quite small, short and robust. Proximal epiphysis partially preserved; cranial component narrow and moderately cranially tilted; lateral condyle caudolaterally rounded and projected; intercondylar eminence tall, thick and elongate; medial condyle not known. Proximal fibular facet large, deep, broad and caudolaterally projected, with a slight distal deflection. Cnemial crest thick and shallow ( Fig. 102f ); peak quite distinct and rugose, crest broadens distally, gently lowers, becomes rounder and merges gently into the shaft. Proximolateral crest raised and rounded proximally, rapidly narrowing and steadily becoming very raised before merging into the distal fibular facet at the midpoint of the shaft. Distal fibular facet extends from the midpoint of the shaft to the distal epiphysis; deep, distinct, slightly convex and slightly craniolaterally projected, particularly proximally. Distal shaft broad, particularly distally. Distal end very broad, with a gently convex trochlear articular surface, roughly rectangular and slightly caudally tilted; medial tuberosity large and elongate, and medial malleolus elongate and ventrally projected with caudal part curving caudomedially.

The tibia of P. otibandus differs from that of P. anak in being shorter, with a relatively slightly broader distal epiphysis; from P. mamkurra sp. nov. in being smaller, with larger, broader proximal fibular facet and a shallower, relatively less distally extensive cnemial crest; from P. viator sp. nov. and P. snewini in being smaller and more robust, with a larger, broader proximal fibular facet, gently cranially tilted cranial section of the proximal epiphysis, and a slightly more curved cnemial crest in cranial view; from P. tumbuna in being more gracile, with a thinner, more raised proximolateral crest, and a less distally extensive cnemial crest with a more defined peak; from C. kitcheneri in having broader proximal fibular facet, thicker proximal part of the proximolateral crest, and a deeper, more distinct distal fibular facet; from O. rufus and M. fuliginosus in being more robust, with a cranially tilted cranial section of the proximal epiphysis, broader proximal fibular facet, relatively longer cnemial crest with less distinct distal peak, thicker proximolateral crest, deeper, more distinct distal fibular facet and more craniocaudally compressed distal epiphysis; and from W. bicolor in being larger, with a deeper proximal fibular facet, thicker proximolateral crest, relatively more elongate cnemial crest with a less angular, less distinct distal peak, and a broader talar trochlea.

Fibula: only known specimen is a fragmentary distal shaft; articulates with the lateral surface of the distal half of the tibia. Proximal end interpreted as being large and broad based on the size of the proximal fibular facet on the tibia. Distal shaft quite deep and gently crescentic in cross-section, thickens distally.

Pes

Calcaneus ( Fig. 103a–f ): short, low and robust. Calcaneal tuberosity broad, low and domed in cross-section, almost squared immediately caudal to the calcaneal head. Caudal epiphysis low and rounded in caudal view with a thin, shallow, transverse channel on the caudal surface. Plantar surface thick, rugose, quite broad and gently narrowing cranially, and curving slightly laterally to a rounded point lateral to the cranial plantar tubercle; a thicker and more plantarly projected caudal section is formed from the caudal epiphysis. Cranial plantar tubercule small, rounded, plantarly projected and immediately caudoplantarly adjacent to the plantar margin of the plantomedial cuboid facet.

Calcaneal head large and broad; midline in the sagittal plane is slightly medially offset relative to that of the calcaneal tuberosity ( Fig. 103a ). Sustentaculum tali broad, thick and rounded with no distinct peak in medial view; projected medially slightly beyond the medial margin of the medial talar facet, extends caudally well past the caudal margins of the talar facets; flexor groove very broad and deep, accentuated by the medial projection of the plantar surface. Fibular facet small, with semi-distinct cranial and caudal components, separated by a broad groove; caudal component quite small, roughly oval, unprojected caudally, slightly projected laterally, and medially semicontinuous with lateral talar facet; cranial component lower than the caudal component, broad, laterally projected and slightly laterally tilted, with the dorsal surface gently concave. Lateral talar facet broad, quite tall, smoothly convex with distinct medial tapering; a rounded, very shallow fossa is immediately cranial to the lateral talar facet, with a small, low, rounded tubercle on the medial margin of the fossa; medial talar facet caudally displaced relative to the lateral facet; small, oval, dorsally slightly projected, orientated caudomedially to craniolaterally and strongly cranially tilted, with a rounded lip along the caudomedial margin; smoothly continues caudally into a very low, rounded tubercle or ridge merging caudally into the dorsolateral margin of the tuberosity.

Talar head facet very small, rounded, abuts the dorsomedial margin of the dorsomedial facet on the medial surface of the calcaneal head. Dorsomedial cuboid facet squarish with a rounded dorsomedial margin, gently convex and slightly dorsally projected; separated from the dorsolateral facet by a deep, bevelled step; small, shallow fossa sits immediately plantarly. Dorsolateral cuboid facet tall, subequal in width to the dorsomedial facet, cranially projected and roughly semicircular, with curved dorsal and lateral margins; extends plantarly and curving medially to be continuous with the plantomedial facet. Plantomedial cuboid facet small, broad, dorsoplantarly short and oblong; extends medially past the midpoint of the dorsomedial facet.

The calcaneus of P. otibandus differs from all compared species in having the calcaneal head slightly medially offset relative to the calcaneal tuberosity. It further differs from P. anak in being smaller and lower, with a relatively shorter, slightly broader tuberosity that is more rounded dorsally in cross-section, less straight, more cranially tapered plantar surface, less rounded, less distinct and less caudolaterally projected caudal component of the fibular facet, less concave plantolateral margin of the dorsolateral-plantomedial facet, and a more laterally tilted dorsomedial cuboid facet; from P. mamkurra sp. nov. in being smaller and lower, with a slightly narrower, more cranially tapered plantar surface, more rounded sustentaculum tali, less bulbous lateral talar facet, relatively smaller medial talar facet that is more cranially tilted and more caudally displaced relative to the lateral facet, more laterally tilted dorsomedial cuboid facet, and a less medially tilted dorsolateral cuboid facet; from P. viator sp. nov. in being smaller, lower, shorter and much more robust, with a lower, more rounded tuberosity in cross-section, relatively narrower dorsomedial cuboid facet, and in having the lateral surface of the calcaneal head beneath the fibular facet dorsoplantarly much shorter and less concave; from P. tumbuna in having a less medially displaced head relative to the tuberosity, more planar plantar surface with less flaring of the medial margin, and a smaller, shallower fossa cranial to the lateral talar facet; from P. dawsonae sp. nov. in having a broader calcaneal tuberosity; from C. kitcheneri in being larger and taller, with a more planar, more cranially extensive and less laterally tilted plantar surface, more dorsally projected medial talar facet, and a less caudally projected, less distinct caudal component of the fibular facet; from O. rufus and M. fuliginosus in being much broader and more robust, with a broadly rounded, domed calcaneal tuberosity in cross-section, more pointed, more medially projected sustentaculum tali, less cranially extensive cranial component of the fibular facet, more bevelled step between the dorsal cuboid facets, and a more curved, less cranially extensive plantar surface that broadens caudally; and from W. bicolor in being larger and relatively broader, with a relatively larger fibular facet and a broader medial talar facet.

Talus ( Fig. 103g –i ): slightly width greater than craniocaudal length. Trochlear crests equal in height, with the medial peak thinner and less rounded. Trochlea is fairly deep and medially skewed ( Fig. 103h ). Medial malleolus large, rounded, smoothly convex, dorsal facing, extends medially and slightly cranially, bounded laterally by a deep, rounded malleolar fossa; rounded, plantomedially projected tubercle situated plantar to the medial malleolus on the medial surface of the talar neck. Talar head broad and distinctly plantarly deflected, creating a concave divot between the head and cranial margin of medial trochlear crest. Facet for the navicular broad dorsally and extending caudoplantarly to beneath anterior margin of medial malleolus. Facet for the cuboid very small, slightly convex and lateral facing, with a very slight cranioplantar tilt. Posterior plantar process rugose, very broad and thickened, deep, plantarly projected and rounded. On the plantar surface, the medial calcaneal facet is rounded and concave, abuts a small, deep, rounded mesial fossa, and the lateral calcaneal facet is very large, broad, deeply concave, becomes deeper laterally.

The talus of P. otibandus differs from that of P. anak in being smaller, with a broader navicular facet that is more obliquely angled in cranial view, larger, more obliquely aligned medial malleolus, and a small tubercle plantar to the medial malleolus on the medial surface; from P. mamkurra sp. nov. in being smaller, with a deeper malleolar fossa, smaller cuboid facet, less medially projected talar head, and a deeper plantar groove between the navicular facet and the posterior plantar tubercle; from P. viator sp. nov. in being smaller, with a shorter, more concave, and more cranially situated malleolar fossa, a dorsal facing medial malleolus, and a deeper plantar groove between the navicular facet and the posterior plantar tubercle; from P. snewini in having a deeper trochlea and a deeper concavity between the posterior plantar tubercle and the talar head; from C. kitcheneri in having a more medially projected medial malleolus, more caudoplantarly extensive navicular facet, a facet for the cuboid present on the navicular head, and a deeper lateral calcaneal facet; from O. rufus in being relatively broader and more caudolaterally extensive, with a deeper trochlea and a larger, more rounded posterior plantar process; from M. fuliginosus in being generally larger, relatively broader and more caudolaterally extensive, with a deeper trochlea and a deeper, broader and more rounded posterior plantar process; and from W. bicolor in being larger and relatively broader, with a more caudoplantarly extensive navicular facet and a broader, more rounded posterior plantar process.

Cuboid ( Figs 103j–l , 104a–d ): square and robust. Dorsomedial calcaneal facet squarish, caudally projected, smoothly concave and subequal to the dorsolateral calcaneal facet, separated by a bevelled step; dorsolateral calcaneal facet tall, gently concave and extending plantarly and slightly medially to be continuous with the plantar calcaneal facet; plantar calcaneal facet broad, dorsoplantarly short, oblong and gently concave, with the medial margin situated lateral to the transverse midpoint of the dorsomedial facet, situated on the caudal base of the lateral plantar tubercle. Dorsal margin of the medial surface marked by a low, rounded ridge projecting medially over a tall, broad fossa for articulation with the caudodorsal part of the ectocuneiform and the craniodorsal part of the navicular.

Facet for the talar head narrow and indistinct. Facet for the navicular small and narrow on the caudal margin of dorsal part of the medial surface, adjacent to the medial margin of the dorsomedial calcaneal facet. Facet for the ectocuneiform very tall and thin, extends from near the dorsal margin of the medial surface past the midpoint of the cranial margin, with a distinct, rounded second facet on the plantomedial surface of the medial plantar tubercle. Lateral plantar tubercle large, broad and quite plantarly projected, oval to round in plantar view; occasionally deflected caudally (see UCMP 70078). Medial plantar tubercle moderately small, rounded, less plantarly projected than the lateral tubercle and slightly medially deflected; separated from the lateral tubercle by a variably deep, narrow flexor groove. Facet for metatarsal IV broad and very gently concave, with the dorsomedial margin medially projected; not continuous plantarly with the small, rounded, plantarly tilted plantar facet for metatarsal IV. Facet for metatarsal V fairly small, rounded, gently concave, slightly plantolaterally tilted and laterally projected.

The cuboid of P. otibandus differs from that of P. anak in being smaller and lower, with less plantarly projected plantar tubercles, and the dorsal and plantar metatarsal IV facets distinct from one another; from P. mamkurra sp. nov. in being smaller, with less distinct step between the dorsal calcaneal facets, slightly narrower dorsolateral calcaneal facet, smaller, less distinct talar head facet, deeper medial fossa for the navicular and ectocuneiform, more plantarly projected lateral plantar tubercle, narrower flexor groove, more laterally tapered metatarsal IV facet that is distinct from the plantar metatarsal IV facet, and a smaller, narrower, more concave metatarsal V facet; from P. viator sp. nov. in being smaller, shorter and relatively broader, with a more plantarly situated navicular facet, less elongate, less plantarly projected plantar tubercles, and a shallower flexor groove; from P. snewini in having less dorsomedially flared dorsomedial section, more level dorsal calcaneal facets in caudal view, more plantarly extensive plantomedial calcaneal facet, much smaller talar facet, and a much larger, more plantomedially projected medial plantar tubercle; from C. kitcheneri in being slightly larger and taller, with a facet for the talar head present, more plantarly projected lateral plantar tubercle, larger, more elongate and more medially situated medial plantar tubercle, and separate dorsal and plantar metatarsal IV facets; from O. rufus in being relatively broader, particularly across the plantar section, with a relatively broader dorsolateral calcaneal facet, a smaller, less distinct facet for the talar head, less plantarly projected lateral plantar tubercle, more medially situated medial plantar tubercle, broader flexor groove, and a more medially situated plantar metatarsal IV facet; from M. fuliginosus in being generally larger and relatively broader, particularly across plantar section, with a smaller, less distinct facet for the talar head, more deeply concave medial fossa for the navicular and ectocuneiform, broader and less plantarly projected lateral plantar tubercle, larger and more medially situated medial plantar tubercle, broader flexor groove, and separate dorsal and plantar metatarsal IV facets; and from W. bicolor in being larger and relatively broader, with a less plantarly projected lateral plantar tubercle and a larger, more plantarly projected medial plantar tuberosity.

Navicular ( Fig. 104a–b, d ): tall, roughly crescentic in medial view and transversely compressed dorsally, broadens gently plantarly, particularly around the laterally flared facet for the ectocuneiform; medial surface rugose. Talar facet smoothly concave and dorsally tilted. Facet for the ectocuneiform tall, gently convex and quite narrow, extends from the dorsal margin of the cranial surface just past the midpoint; plantar component broadens and flares laterally. Facet for the entocuneiform quite small and narrow, oval and situated slightly plantar of the midpoint of the cranial surface, level with the plantar margin of the ectocuneiform facet.

The navicular of P. otibandus differs from that of P. mamkurra sp. nov. in being smaller, and shallower relative to height, with a more laterally flared dorsal ectocuneiform facet and a less medially tilted facet for the entocuneiform; from P. viator sp. nov. in being smaller and slightly shallower, with a more medially deflected plantar section and a dorsoplantarly shorter facet for the ectocuneiform; from C. kitcheneri in being taller and relatively shallower; from O. rufus in being taller and relatively shallower, with a more expanded plantar section, and a slightly more plantarly situated facet for the entocuneiform; from M. fuliginosus in being larger and much taller; and from W. bicolor in being larger, with a more medially flared plantar section.

Ectocuneiform ( Fig. 104a–b, d ): tall and quite transversely compressed; dorsal margin forms a thick, rounded-triangular mesial point, accommodating the articulation of the dorsolateral surface with metatarsal IV. Facet for the navicular tall and quite narrow transversely, broadens plantarly, occupies the entire caudal surface. Facet for metatarsal III concave, quite tall and narrow, occupies the dorsal section of the cranial surface. Facet for the mesocuneiform very small and roughly oval, on the cranial section around the midpoint of the medial surface, plantar to the metatarsal III facet. Medial surface has the dorsal section smooth and gently convex, plantar section pitted and rugose. A small, thin eminence is present on the caudal part of the midpoint of the medial surface, probably for articulation with the entocuneiform.

The ectocuneiform of P. otibandus differs from all compared species in its rounded-triangular dorsal margin. It further differs from P.mamkurra sp. nov. in being smaller and relatively slightly dorsoventrally shorter; from P. viator sp. nov. in being slightly less transversely compressed and relatively taller, with a less deeply concave entocuneiform facet; from C. kitcheneri in having a slightly larger and more cranial facing facet for the mesocuneiform; from O. rufus in having a smaller cranial eminence, more plantarly extensive articulation with the navicular, and a less cranially deflected plantar process; from M. fuliginosus in being larger and taller, with a more plantarly extensive facet for the navicular; and from W. bicolor in being larger and slightly less transversely compressed, with a less concave, slightly more plantarly extensive navicular facet.

Metatarsals II and III ( Fig. 104a–d ): both very gracile; III longer than II, both slightly shorter than metatarsal IV; II straight, III very slightly bowed laterally. Proximal end of metatarsal III: articulates with the mesocuneiform, ectocuneiform and metatarsals II and IV; tall and narrow with a smoothly convex ectocuneiform facet; entocuneiform facet small, rounded and situated on the plantar part of the medial surface. Proximal end of metatarsal II: articulates with metatarsal III and possibly with both the entocuneiform and mesocuneiform; relatively small and unflared compared to the metatarsal III proximal end. Shafts transversely compressed proximally; metatarsal III shaft rapidly decreases in height from the proximal end, becomes rounded in cross-section and gently tapers distally; metatarsal II broadens slightly and is un-tapered. Distal ends small, bulbous and rounded. The phalanges are not known.

Metatarsals II and III of P. otibandus differ from those of all compared taxa in having shafts that are less laterally bowed. They further differ from those of P. viator sp. nov. in being slightly more robust and longer relative to the length of metatarsal IV; from M. fuliginosus and O. rufus in being much shorter, more robust and longer relative to length of metatarsal IV, with a taller proximal end for articulation with metatarsal III; and from W. bicolor in being larger and more robust.

Metatarsal IV ( Fig. 104a–f ): short and robust. Proximal end dorsal margin flat to gently rounded; dorsal cuboid facet broad, with the lateral section flat to gently convex and the medial section flat to gently concave; dorsal facet separate from the plantar cuboid facet, separated by a broad, very shallow transverse proximal fossa; plantar cuboid facet small, rounded, slightly proximally projected and tilted dorsally and slightly medially, extends plantarly onto the proximal surface of the plantar tubercle. Facet for the dorsolateral section of the ectocuneiform small, semicircular and distinct, situated against the dorsal margin of the medial surface of the proximal end, facing medially. Plantar tubercle quite small, plantarly projected and slightly proximally deflected. Proximal plantar sesamoid facet small, rounded to squarish and laterally tilted. Facet for metatarsal III indistinct, situated in the shallow, rugose metatarsal III fossa, bordered dorsally by a thin ridge extending plantodistally from the dorsomedial corner of the dorsal cuboid facet. Facet for the ectocuneiform very small, tall and thin, abuts the midpoint of the proximal margin of the medial surface of the shaft; smaller facet for articulation with the plantolateral section of the ectocuneiform occasionally present on the proximal section of the medial surface of the plantar tubercle (see UCMP 70584, L metatarsal IV). Facet for metatarsal V tall, quite deep, distally tilted, gently concave and oblong, projects proximally or proximoplantarly to create one or two small, rounded eminences on the lateral margin of proximal fossa in proximal surface.

Plantar ridge broad, weakly raised ( Fig. 104e ), rugose, rounded to square in cross-section, extends distally from the distal base of plantar tubercle to slowly merge with plantar shaft. Shaft flat to very slightly rounded dorsally; height tapers distally, broadens gently to distal end. Distal end large with fossae for collateral ligaments deep and rounded; keel rounded and more plantarly projected than medial and lateral eminences.

The metatarsal IV of P. otibandus cannot be differentiated from that of P. tumbuna . It differs from that of P. anak , P. mamkurra sp. nov. and P. dawsonae sp. nov. in being smaller and more robust, with separate dorsal and plantar cuboid facets ( Fig. 104f ) and a less raised plantar ridge; from P. viator sp. nov. in being smaller and more robust, with separate dorsal and plantar cuboid facets, a less raised plantar ridge and a shaft with a weaker proximal waist; from P. snewini in being slightly shorter and more robust, with a smaller proximal cuboid fossa; from C. kitcheneri in being broader, with separate dorsal and plantar cuboid facets, less narrowing of the proximal shaft, and a more raised plantar ridge; from O. rufus and M. fuliginosus in being much shorter, broader and more robust, with separate dorsal and plantar cuboid facets, a lower plantar ridge, and a more plantarly projected proximal plantar tubercle; and from W. bicolor in being much larger, relatively broader and more robust, with a relatively slightly larger plantar tubercle.

Metatarsal V ( Fig. 104g –k ): very short, robust and transversely compressed with a slight medial tilt; curves slightly laterally distally; slightly arched in lateral view; length to distal facet width index ~4–4.7. Proximolateral process blunt, rugose, proximodistally quite short and transversely compressed. Facet for the cuboid very broad, gently concave and slightly raised at distal margin, mostly proximal facing; extends from proximal surface of the medial plantar tubercle across proximal surface of the shaft onto base of dorsomedial surface of proximolateral process and dorsolaterally over dorsal surface of the base of proximolateral process. Facet for metatarsal IV broad, gently convex, slightly raised and rounded to square; proximally abuts facet for the cuboid, extends medially onto dorsomedial surface of the medial plantar tubercle. Lateral plantar tuberosity broad, long and rugose, separated from medial plantar tubercle by narrow, shallow channel. Medial plantar tubercle very small, sometimes indistinct, gently medially projected. Distal end broad; medial fossa for the collateral ligaments larger and deeper than the lateral fossa.

The metatarsal V of P. otibandus differs from that of P. anak in being smaller, with a relatively smaller proximolateral process and a relatively smaller, less proximomedially projected medial plantar tubercle; from P. mamkurra sp. nov. in being smaller and narrower, with a smaller, slightly narrower cuboid facet, deeper plantar groove,and a larger lateral plantar tuberosity;from P.viator sp. nov. in being smaller, shorter and less transversely compressed, with a broader, more medially situated cuboid facet and a more medially extensive metatarsal IV facet that is less distinct from the cuboid facet; from P. tumbuna in being slightly more gracile and more transversely compressed, with dorsoplantarly shorter proximolateral process, proximodistally longer metatarsal IV facet and larger medial plantar tubercle; from P. dawsonae sp. nov. in being shorter, with more dorsally projected cuboid facet and slightly broader distal end; from C. kitcheneri in being shorter and broader, lacking slight kink of arch of the shaft immediately proximal to midpoint in lateral view, with a larger medial plantar tubercle and lateral plantar tuberosity, and a deeper, more distinct plantar groove; from O. rufus and M. fuliginosus in being much shorter, broader, less transversely compressed, and less arched in lateral view, with a larger medial plantar tubercle and a deeper, more distinct plantar groove; and from W. bicolor in being larger, relatively broader and more robust.

Pedal phalanges ( Fig. 105 & 106 ): Proximal phalanx IV: short, robust and slightly dorsoplantarly compressed, with a slight waist on the shaft. Proximal end domed, with the proximal plantar tubercles low and rounded; proximal articular facet broad and gently concave with a rounded dorsal margin. Distal end with large, very shallow fossae for the collateral ligaments; trochlea gently concave. Middle phalanx IV: short and broad; proximal end broad, with the proximal plantar tubercles very low and projected slightly proximally. Proximal articular surface dorsally rounded, concave and tilted slightly dorsally. Shaft height decreases distally, with a very slight waist. Distal end with quite deep fossae for the collateral ligaments; trochlea narrow and very slightly concave dorsally, deepens and broadens plantarly. Distal phalanx IV: quite short, broad and robust; proximal articular facet concave and roughly pentagonal, forms a rounded, slightly proximodorsally projected dorsal peak. Flexor tubercle large and plantarly projected, oval in plantar view. Shaft with a rounded dorsal peak ( Fig. 105i ), curves gently downward in lateral view.

Proximal phalanx V: quite tall, robust and asymmetrical; shaft laterally deflected relative to the proximal surface. Proximal end slightly broader than tall; plantar tubercles large, rounded and rugose, lateral tubercle projected plantolaterally past the articular surface; proximal articular surface round, gently concave and medially displaced in proximal view. Shaft rounded and triangular in cross-section. Distal end with very shallow fossae for the collateral ligaments; trochlea broad and shallow, and articular surface not extensive dorsally. Middle phalanx V: very short, broad and very dorsoplantarly compressed. Proximal end with very low plantar tubercles; proximal articular surface gently concave and tilted strongly dorsally. Shaft very short, decreases in height distally, with no waist. Distal end with fossae for collateral ligaments very shallow and tall. Distal phalanx V: tall, robust and asymmetrical, with the dorsal peak of the shaft and the proximal end medially displaced; small, deep fossae for the collateral ligaments. Plantar tubercle large and rounded in plantar view. Shaft with a rounded dorsal peak and a strongly convex plantar margin in cross-section. Distal end abraded in available specimens.

The pedal phalanges of P. otibandus differ from those of P. anak in being slightly smaller, with middle phalanx IV less dorsoplantarly compressed ( Fig. 105h ) and lacking large, transversely flared plantar tubercles, distal phalanx IV with a more rounded dorsal peak, and proximal phalanx V with a less distinct waist; from P. mamkurra sp. nov. in being smaller and shorter, with proximal phalanx IV with a narrower distal end, and middle phalanx IV with a narrower trochlea; from P. viator sp. nov. in being slightly smaller, with proximal phalanx IV shorter with a broader waist, distal phalanx IV more dorsoplantarly compressed with a more rounded dorsal peak and a less plantarly curved shaft, proximal phalanx V with a less concave proximal articular surface, a more laterally deflected shaft, and a narrower trochlea, middle phalanx V shorter with a less medially tilted proximal surface, and distal phalanx V with a more rounded dorsal peak; from P. snewini in having relatively narrower middle phalanx IV across the proximal end and a slightly broader distal phalanx IV with a more rounded dorsal peak; from P. dawsonae sp. nov. in having proximal phalanx IV with a less proximodorsally extensive distal articular surface; from C. kitcheneri in being shorter, lower, broader and more robust, with broader, shallower trochleae, middle phalanges with more dorsally tilted proximal surfaces, and distal phalanges with much more rounded, less pointed dorsal peaks; from O. rufus and M. fuliginosus in being shorter, lower, broader and much more robust, particularly the middle phalanges, with proximal phalanx IV having a broader waist, the middle phalanges with a more dorsally tilted proximal surface, and distal phalanges with a more rounded, less pointed dorsal peak in cross-section and a more plantarly curved shaft in lateral view; and from W. bicolor in being larger, relatively broader and more robust.

Remarks:

Holotypes of P. chinchillaensis and P. devisi

During the printing of Bartholomai (1973), an error occurred wherein the images of the holotypes of P. chinchillaensis and P. devisi and their respective captions were inadvertently switched. This resulted in the image of the holotype for P. chinchillaensis ( Bartholomai 1973, pl. 23, figs 3 & 4) being labelled as the holotype for P. devisi , and the image of the holotype for P. devisi ( Bartholomai 1973, pl. 21, figs 3 & 4), being labelled as the holotype for P. chinchillaensis . Bartholomai (1975) included an erratum correcting this mistake. During I.A.R.K.’s visit to the palaeontological collection of the Queensland Museum in late 2018, the curator, Dr Scott Hocknull, and I.A.R.K. noted that the registration numbers of each holotype reflected those assigned to them incorrectly in plates 21 & 23 of Bartholomai (1973). Dr Hocknull reviewed the situation, and, informed by the apparent intent of Bartholomai (1973) and by the descriptions of the specimens in the fossil register of the Queensland Museum, altered the number of each type to its original designation in the species diagnosis of Bartholomai (1973). The official stance of the museum is that the holotype of P. chinchillaensis has the registration number QM F5246 and that the holotype of P. devisi has the registration number QM F4710.

Identities of P. otibandus and P. chinchillaensis

Prior to this study, there was some cause to doubt the separate taxonomic identities of P. otibandus and P. chinchillaensis . Protemnodon otibandus was the first species of Protemnodon of undoubted Pliocene age to be described, and the first from New Guinea ( Plane 1967). Later, Plane (1972) tentatively allocated a partial maxilla from Lake Tyers, southeastern Victoria, to P. otibandus . Despite this, when P. chinchillaensis was described from the Pliocene material of the Chinchilla Sand, Bartholomai (1973) made comparisons with all species of Protemnodon recognised at the time with the exception of P. otibandus , the species with which it was most similar. Flannery & Archer (1984) noted the lack of a urocrista on the anterior upper molars of P. chinchillaensis , the presence of which was implied therein to be autapomorphic in P. otibandus , though Flannery (1994) stated ‘ Protemnodon otibandus is extremely similar in morphology to P. chinchillaensis . They may even be conspecific’ (p. 45).

The New Guinean material of P. otibandus is very restricted in geographic area and time, contrasting with other species of Protemnodon , which are sampled over longer time intervals across wider geographic areas. With the exception of a single maxilla of probable Pliocene age preserving P3–M3, from near Koroba in the Hela Province of montane central PNG ( Flannery 1990a), all New Guinean material of P. otibandus comes from the Awe LF of the Otibanda Fm. in Morobe Province, eastern PNG ( Fig. 1 ) ( Plane 1967; Flannery 1994). This sample, by the standards of the better-sampled P. anak , shows tightly clustered dental dimensions and a more uniform craniodental and postcranial morphology, insofar as both are known. That said, various features that have been described as diagnostic of P. otibandus are in fact variable within the type series. Plane (1967) described P. otibandus as having a distinct buccal cuspid in the talonid basin of the m1. However, this cuspid is variable within the paratypes of P. otibandus —for e.g., extremely reduced in UCMP 69896 and absent from UCMP 45246—and thus its absence from the holotype of P. chinchillaensis is not considered taxonomically significant. The dental morphology of P. chinchillaensis was described by Bartholomai (1973) in the species diagnosis as differing from other members of the genus in having relatively curved molar links, a shallow mandibular ramus and swollen anterolingual protolophid bases. It is not clear whether the phrase ‘molar links’ refers to the upper or lower dentition, or which crista(e) and/or cristid(s) in particular are more curved in this taxon. The paracristid and cristid obliqua on the lower molars were described as curved in the species description, but this is a feature of all species of Protemnodon , and neither the paracristid nor cristid obliqua in any specimens referred to P. chinchillaensis by Bartholomai (1973) appear especially curved. The postprotocrista in the upper molars was described as curved in the species description, but this does not appear to be especially the case in any specimens of P. chinchillaensis examined, including the two figured partial maxillae (QM F5239 and QM F4719; Bartholomai 1973, pl. 20). The curvature of the postparacrista was not mentioned, though this was observed to regularly vary even within individuals of species of Protemnodon , including a specimen figured by Bartholomai (1973; QM F4719, pl. 20).

Dentary height is quite variable within species of Protemnodon ( Fig. 110 ). Within the sample of P. anak , the spread in the measurements of this feature encompasses that of all Pliocene species of Protemnodon , so the relatively small differences in dentary height between the small samples of P. chinchillaensis and P. otibandus can be effectively discounted.

It is unclear what Bartholomai (1973) meant by ‘swollen anterolingual protolophid base’ (p. 352), as no swelling in this part of the lower molars of the holotype and referred specimens of P. chinchillaensis was identified in this study. Unpublished research suggests that this trait was not evident in any specimen (Lyndall Dawson, pers. comm. 2001). It is possible that the use of the term protolophid by Bartholomai (1973) was the result of a lapsus calami and that the author instead intended to refer to the anterolingual base of the protoloph of the upper molars, as this area of the upper molar is indeed distinctly convex, with the degree of swelling decreasing toward the posterior of the molar row. Regardless, this trait is shared by specimens of P. otibandus . Therefore, as the holotype of P. chinchillaensis , a dentary, has no features to confidently distinguish it from the type material of P. otibandus , and nor indeed does any other referred element, we find P. chinchillaensis Bartholomai, 1973 to be a junior synonym of P. otibandus Plane, 1967 .

Figures

FIGURE 1. map showing locations of Pliocene deposits inAustralia and New Guinea yielding material of species of Protemnodon, including that not confidently referable to species level. 1, Mogorafugwa, Hela Province; 2, Lower Kikori River, Gulf Province; 3, Otibanda, Morobe Province; 4, Toolapinna Waterhole, Warburton River; 5, Site 4, Lake Kanunka; 6, Lawson–Daily Quarry, Lake Palankarinna; 7, Bluff Downs, Allingham; 8, Rifle Range/Sand Scree locality/Chinchilla, Chinchilla Sands; 9, Bow, Hunter Valley; 10, Big Sink, Wellington Valley; 11, Hamilton, Glenelg Shire; 12, Lake Tyers, East Gippsland Shire.

FIGURE 98. upper dentition of P. otibandus: (a–b) surface scan images of left I1 of UCMP 45246 in (a) lateral/buccal, and (b) anterior views; (c–d) surface scan images of left premaxilla fragment with partial I1 and I2–3 of paratype UCMP 69832 in (c) lateral/buccal, and (d) occlusal views; (e–g) surface scan images of partial left maxilla with P3–M3 of paratype UCMP 69857 in (e) buccal, (f) lingual, and (g) occlusal views; and (h) partial right maxilla of NMV P22650 from Jemmy’s Point, Lake Tyers, in occlusal view.

FIGURE 99. dentaries and lower dentition of P. otibandus: (a–b) surface scan images of re-articulated right dentary of holotype CPC 6771 and left dentary of UCMP 69895 in (a) occlusal, and (b) ventral views; (c–d) surface scan images of right dentary of CPC 6771 in (c) buccal, and (d) lingual views; (e) partial right dentary of SAMA P50566 from Toolapinna Waterhole, Lake Eyre Basin, in buccal view; and (f–h) surface scan images of right p3–m4 of CPC 6771 in (f) occlusal, (g) buccal, and (h) lingual views.

FIGURE 100. surface scan images of right upper forelimb elements of P. otibandus: (a–c) clavicle of UCMP 70045 in (a) anterior, (b) dorsal, and (c) ventral views; (d–e) distal humeral fragment of UCMP 70059 in (d) caudal, and (e) cranial views; and (f–g) radius of UCMP 70059 in (f) cranial, and (g) caudal views.

FIGURE 101. surface scan images of right lower forelimb elements of P. otibandus UCMP 70059: (a–d) partial ulna in (a) lateral, (b) medial, (c) caudal, and (d) cranial views; and (e–i) partial articulated manus, with ulnar styloid process attached, in (e) dorsal, (f) dorsolateral, (g) palmar, (h) lateral, and (i) medial views. Elements not preserved in the manus are the trapezoid, trapezium, and distal phalanges I and IV.

FIGURE 102. surface scan images of partial hindlimb elements of P. otibandus: (a) proximal right femoral fragment of UCMP 70665 in dorsal view; (b–c) partial proximal right femur of UCMP 45344 in (b) dorsal, and (c) ventral views; (d–e) left distal femoral epiphysis of UCMP 45344 in (d) distal, and (e) lateral views; (f–i) partial proximal left tibia of UCMP 70584 in (f) lateral, (g) medial, (h) cranial, and (i) proximal views; and (j–k) partial right tibial shaft in (j) lateral, and (k) medial views.

FIGURE 103. left tarsal elements of P. otibandus: (a–d, f) surface scan images of partial calcaneus of UCMP 70584 in (a) dorsal, (b) plantar, (c) medial, (d) lateral, and (f) caudodorsal views; (e) calcaneus of UCMP 45247 in cranial view; (g–i) surface scan images of talus of UCMP 70584 in (g) dorsal, (h) cranial, and (i) medial views; and (j–l) surface scan images of cuboid of UCMP 70078 in (j) caudal, (k) cranial, and (l) medial views.

FIGURE 104. right tarsal elements of P. otibandus: (a–d) articulated cuboid, navicular, ectocuneiform, and metatarsals II–IV of UCMP 45247 in (a) dorsal, (b) plantar, (c) lateral, and (d) medial views; (e–f) surface scan images of metatarsal IV of UCMP 70584 in (e) lateral, and (f) proximal views; and (g–k) surface scan images of metatarsal V of UCMP 70585 in (g) dorsal, (h) plantar, (i) medial, (j) lateral, and (k) proximal views.

FIGURE 105. surface scan images of left (a–d) proximal, (e–h) middle, and (i–l) distal pedal phalanges IV of P. otibandus specimen UCMP 70584 in: (a, e, i) dorsal, (b, f, j) plantar, (c, g, k) medial, and (d, h, l) proximal views.

FIGURE 106. surface scan images of right (a–d) proximal pedal phalanges V, and (e–h) articulated middle and partial distal pedal phalanges V of P. otibandus specimen UCMP 45247 in: (a, e) dorsal, (b, f) plantar, (c, g) medial, and (d, h) proximal views.

FIGURE 110. scatterplot of lower (mandibular) diastema length versus height of the mandibular corpus beneath m1 in specimens of P.anak, P. mamkurra sp. nov., P. viator sp. nov., P. dawsonae sp. nov., P. snewini, P. otibandus, P. tumbuna, and four extrageneric taxa.