SPECIES PINPANETTA TEDFORDI SP. NOV. (FIG. 1)

Holotype: SAM P.41257, complete R humerus (Fig. 1A, F), reassembled from two pieces; shaft with some wear on distal margin of bicipital crest and on caudal shaft surface; light brown in colour.

Diagnosis: A species of Pinpanetta about the size of Oxyura australis, characterized by the following features: dorsal pneumotricipital fossa excavated below head; elongate deltoid crest with about 50% length extending distad of bicipital crest; ventral pneumotricipital fossa, from median crest, wider than its length measured from the ventral tubercle to the distal end of the bicipital crest – shaft junction; shaft narrows distally; facet for the attachment of anterior ligament directed distoventrally; and on ventral facies, attachment of pronator brevis positioned towards cranial facies, not centrally.

Etymology: For R. H. (Dick) Tedford whose efforts over many years have revealed much about the Namba and Etadunna Formations and their contained faunas and whose expeditions collected many of the following specimens.

Type locality: Young Bucks Quarry, site code RV-9002, Lake Palankarinna, 28° 47 ′ S, 138° 24 ′ E, Tirari Subbasin, Lake Eyre Basin, SA, collected N.S. Pledge et al., xii.1992.

Horizon: Stratigraphy/Age/Fauna: Etadunna Formation, Late Oligocene 24–26 Mya, Minkana LF, Zone A.

Distribution: Late Oligocene (24–26 Mya): Lake Palankarinna, Etadunna Formation, Minkana LF,

Zone A and Ditjimanka LF, Zone B, Member 7; Lake Pinpa, Namba Formation, Pinpa LF.

Measurements of holotype: TL = 65.6 mm, PW = (maximum width from dorsal tubercle) 14.5 mm, SW = 4.0 mm, DW = 9.0 mm, depth dorsal condyle = 5.3 mm.

Paratypes: Lake Palankarinna, Etadunna Formation: SAM P.42699, s+dR humerus, Neville’s Nirvana, Minkina LF, Zone A, collection code VSQ 1978- 40P. UCMP 46173, s+dL humerus, Tedford Locality Site 2, Ditjimanka LF, Zone B, Member 7, site code UCMP V-5375, collected by R. A. Stirton 1954, collection code RAS #4803. UCMP 56998, well preserved R humerus with the shaft broken and joined with some plaster infill caudally, Stirton Site 2, Ditjimanka LF, Zone B, Member 7, site code UCMP V-5375, collected by R. H. Tedford et al., 1957, collection code RHT#450 (Fig. 1B, G).

Lake Pinpa; Namba Formation, Pinpa LF: SAM P.43133 (formerly AMNH 10957), dR humerus, collected by R. H. Tedford et al., 1971 at Site C, collection code QMAM 151; SAM P.43130 (formerly AMNH 10835), d+sL humerus, collected by R. H. Tedford et al., 1971 at Site C, collection code QMAM 252.

Referred material: Humeri – SAM P.23480, part pR humerus, Lake Pinpa, Namba Formation, Pinpa LF. SAM P.27846, dR humerus, west of site SIAM, Lake Palankarinna, Etadunna Formation, Ditjimanka LF, Zone B. SAM P.41262, dL humerus, White Sands Basin, Lake Palankarinna, Etadunna Formation, Ditjimanka LF, Zone B. QM F52743 (= AR17105), dL humerus, Ringtail Site, Gag Plateau, System C, Riversleigh.

Measurements: See Table 1.

Description and comparison: Humeri of Pi. tedfordi have the following additional features: dorsal pneumotricipital fossa variably excavated under the head, slightly in holotype, marked in UCMP 56998 as in Malacorhynchus; pit for attachment of ligamentum collaterale dorsale on dorsal face of ectepicondyle, deep, divided by median ridge as in all anatids, although this median ridge is unusually weak in SAM P.41257; olecranal fossa well marked; brachial fossa elongate, aligned up shaft, in holotype c. 2.1 mm wide by 5 mm long with proximal dorsal margin barely extending past midshaft width, relatively deeper and extends closer to dorsal margin in other specimens, e.g. UCMP 46173, UCMP 56998, SAM P.43133.

Although distinguished from all oxyurines as indicated in the generic description, humeri of Pinpanetta tedfordi are most similar to those of Oxyura and Malacorhynchus. Both are distinguished from Pi. tedfordi by a marked notch at the ventral end of the capital groove and a shorter deltoid crest. Oxyura further differs as follows: relatively wider ventral pneumotricipital fossa and bicipital crest; distinct groove dorsad of median crest; attachment of pronator brevis fused with ventral facies of ventral epicondyle; and attachment of anterior ligament not buttressed anteriorly. Malacorhynchus humeri further differ by: lack of distal narrowing of the shaft; pocket of ventral pneumotricipital fossa much deeper; distal margin of bicipital crest more convex; facet for attachment of anterior ligament more distally directed; attachment of pronator brevis on ventral facies more central.

The New Zealand Early Miocene fossils Manuherikia and Dunstanetta share with Pi. tedfordi a distally narrowing shaft, but differ in the features listed above, notably with a marked notch in their proximal profile, a shorter deltoid crest, an elongate dorsal tubercle, a deeper ventral pneumotricipital fossa that extends under the median crest, and a relatively wider dorsal pneumotricipital fossa.

QM F52743, from Ringtail Site, System C, is one of only two confirmed anatid bones from the Carl Creek limestone at Riversleigh. It is slightly larger but otherwise indistinguishable from SAM P.43130 from the Namba Formation, which is one of the larger specimens attributed to Pinpanetta tedfordi (Table 1).