Pinpanetta fromensis
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https://doi.org/ 10.1111/j.1096-3642.2008.00483.x |
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https://treatment.plazi.org/id/F57887C5-FFB1-9230-9EB8-FBF671C13111 |
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Felipe |
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Pinpanetta fromensis |
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SPECIES PINPANETTA FROMENSIS
SP. NOV. ( FIGS 1 View Figure 1 , 4 View Figure 4 )
Holotype: SAM P.43128 (formerly AMNH 10736 About AMNH ), R humerus ( Fig. 1E, J View Figure 1 ), reassembled from two pieces, missing proximal part of the deltoid crest, and for which the head has been broken off and reattached, stained light brown.
Diagnosis: A very small duck, about the size of the New Zealand Miocene Man. minuta , distinguished from its congeners as follows: smallest member of genus; shorter deltoid crest with c. 35% length extending distad of bicipital crest; ventral pneumotricipital fossa as wide as long; dorsal pneumotricipital fossa relatively deeper, stepped down from capital groove, distally maintains groove dorsad of median crest; capital groove forms shallow notch proximally; shaft lacks distal narrowing; and facet for attachment of anterior ligament directed cranially, rather than distoventrally.
Etymology: After Lake Frome and Frome Downs Station, around or on which many of the fossil sites producing the fossils described here have been found.
Type locality: Lake Pinpa (= Pine Lake ), 31° 8 ′ S, 140° 13 ′ E, Lake Eyre Basin , Callabonna (= Tarkarooloo) Sub-basin, SA GoogleMaps , Site C, the area extending north from the E-W cross lake track to about the point marked by the CURNAMONA (prov. ed.) sheet grid coordinates 317148 ( R. H. Tedford, pers. comm. 30 Aug 2006), collected by R . H. Tedford 1971, collection code QMAM 243 .
Horizon: Stratigraphy/Age/Fauna: Namba Formation, Late Oligocene 24–26 Mya, Pinpa LF.
Distribution: Late Oligocene (24–26 Mya): Lake Pinpa, Namba Formation, Pinpa LF. Lake Palankarinna, Etadunna Formation, Minkina LF, Zone A; Ditjimanka LF, Zone B; Ngama LF, Zone D, Member 8.
Measurements of holotype: TL = 50.85 mm, PW from dorsal tubercle = 11.0 mm, length deltoid crest = 14.4 mm, SW = 3.8 mm, DW = 8.3 mm, depth dorsal condyle = 4.8 mm.
Paratypes: SAM P.42675, pL humerus with worn ventral margin to bicipital crest, and SAM P.42676, dL humerus ( DW = 7.8 mm, SW = 3.8 mm), both Site 2, Billeroo Creek, 31° 06.205 ′ S; 140° 13.912 ′ E; Namba Formation, Pinpa LF, collected by GoogleMaps THW and A. Camens, June 2007 .
Referred material: The following specimens are referred to Pi. fromensis : those other than humeri on the basis of expected size given the size of the humerus.
Humerus: SAM P.42674, dL humerus, SAM P.42677, worn dR humerus, both Site 2, Billeroo Creek, 31° 06.205 ′ S 140° 13.912 ′ E, Namba Formation, Pinpa LF GoogleMaps . AMNH 10954 About AMNH , pL humerus; Lake Pinpa , Site C, collection code QMAM 151 , Namba Formation , Pinpa LF, measurements – PW = 11.1 mm.
Description: The reconstructed holotype humerus of Pi. fromensis retains damage to the ventral side of the head resulting in loss of the floor of the capital groove and so preventing the form of the end of the capital incision from being determined. However, AMNH 10954 reveals the proximal profile to have a shallow notch, one deeper than the other Pinpanetta species. The deltoid crest is missing the proximal 5 mm but the remaining section is relatively high, extending 3.2 mm above the adjacent cranial surface. It is concave dorsally, and the attachment scar for m. latissimus dorsi posterioris links to its distal end before extending farther distally.
Pinpanetta fromensis differs from Pi. tedfordi and Pi. vickersrichae as follows: dorsal pneumotricipital fossa more deeply excavated, so capital groove opens to fossa from shelf, more excavated under head, and fossa forms a groove adjacent to median crest; deltoid crest shorter. It differs from Pi. tedfordi by the ventral pneumotricipital fossa being as wide as long and that the shaft diameter does not narrow distally.
Humeri of Mal. membranaceus are only slightly larger than Pi. fromensis and have a similar development of the dorsal pneumotricipital fossa, e.g. SAM B.39385; however, they differ as follows: ventral end of the capital groove with more distinct notch in proximal profile; ventral pneumotricipital fossa relatively wider; deltoid crest shorter, beside whose distal end the attachment scar for m. latissimus dorsi posterioris commences and passes distad of without connection; brachial fossa smaller; facet for attachment of anterior ligament craniodistally directed (rather than cranioventrally).
Humeri of the similar-sized Man. minuta of the St Bathans Fauna in New Zealand differ from those of Pi. fromensis as follows: dorsal tubercle distinctly elongate rather than about as wide as long; proximal profile at ventral end of capital groove distinctly notched; ridge for attachment of supraspinatus, although extending to level with end of bicipital crest in both taxa, is much less prominent, such that there is no distinct groove dorsad of median crest; intumescentia humeri less inflated cranially; deltoid crest less elevated from cranial surface; brachial fossa markedly deepened distoventrally rather than relatively flat and even depth.
The ventral tubercle extends at right angles to the ventral pneumotricipital fossa in Pi. fromensis . In all diving taxa, it is directed slightly distally to overhang the fossa, sometimes markedly, e.g. Oxyura . The deeper dorsal pneumotricipital fossa may be associated with a diving habit as it is deepened and broadened to an extreme in Oxyura ; however, it is deep in Malacorhynchus which is not a specialized diving taxon. Most specialized divers have a distally narrow humeral shaft, e.g. Oxyura , Aythya, Mergus , a feature not seen in Pi. fromensis . Similarly, the facet for the attachment of the anterior ligament is directed cranially, rather than distoventrally as seen in specialist divers across diverse clades of anatids e.g. Oxyura , Aythya , and Mergus . These observations suggest that P. fromensis was not a specialized diver, and in this was similar to Pi. vickersrichae .
Ulna: SAM P.22837, L ulna, Mammalon Hill, Lake Palankarinna, Etadunna Formation, Ngama LF, Zone D, Member 8, measurements – preserved length = 44.7 mm, estimated TL = 46 mm.
The single available specimen is complete, but worn proximally so that the structure of the dorsal cotylar process and of the tuber. bicipitale ulnae in the incisura radialis is undeterminable. It has the following features: brachial fossa shallow; tuberculum for ventral collateral ligament not separated from ventral cotyla by deep groove (as in Man. minuta ). It is smaller than ulnae of Nettapus with which it shares a shallow brachial fossa. If correctly associated with the humerus, this taxon has a comparatively short ulna.
Carpometacarpus ( Fig. 4 View Figure 4 ): SAM P.42700, L carpometacarpus ( Fig. 4A–C View Figure 4 ), Neville’s Nirvana, Lake Palankarinna, collection code VSQ 1978-40P, Etadunna Formation, Minkina LF, Zone A, measurements – TL = 31.8 mm, PW = 7.6 mm. AMNH 10938, L carpometacarpus lacking only the minor metacarpal, Lake Pinpa, Site C, Namba Formation, Pinpa LF, measurements – TL = 29.0 mm, PW = 7.1 mm. SAM P.41261, worn L carpometacarpus, White Sands Basin, Lake Palankarinna, Etadunna Formation, Ditjimanka LF, Zone B, measurements – estimated length = 29.5 mm, PW = 6.5 mm. AMNH 10725, worn pR carpometacarpus, Lake Pinpa, Site C, collection code QMAM 264, Namba Formation, Pinpa LF. AMNH 10745, pL carpometacarpus, Lake Pinpa, Site C, Namba Formation, Pinpa LF, measurements – PW = 7.0 mm. AMNH 10748, worn L carpometacarpus, Lake Pinpa, Site C, collection code QMAM 243, Namba Formation, Pinpa LF, measurements – PW = 6.9 mm. AMNH 10951, pR carpometacarpus, Lake Pinpa, Site C, collection code QMAM 151, Namba Formation, Pinpa LF, measurements – PW = 6.7 mm.
The well-preserved specimens SAM P.42700 and AMNH 10938 enable the following character states to be determined: external rim of trochlea carpalis with a shallow carpal notch; both the anterior carpal fossa and cuneiform fossa are present, deep; internal carpal fossa deep, distinct foramen in base, separated from extensor process by rounded ridge; one ligamental facet for ligamentum ulnocarpo-metacarpale dorsale below the carpal rim (not two); short proximal synostosis or region from intermetacarpal space to proc. alularis (pollical facet); minor metacarpal not grooved at the proximal synostosis; flexor attachment marked by single scar distal of proximal synostosis of minor and major metacarpals; distal synostosis shorter than distal width; facets for digits II and III of approximate equal distal length. These specimens are slightly smaller than that of Nettapus , and bigger than those of Man. minuta .
Coracoid ( Fig. 4 View Figure 4 ): SAM P.41301, worn R coracoid ( Fig. 4D View Figure 4 ), with the acrocoracoid, the tip of the procoracoid, the tip of the medial angle, and the lateral process missing, SAM North (a white sand locality), Lake Palankarinna, 28° 46.503 ′ S; 138° 24.164 ′ E, Etadunna Formation, Ditjimanka LF, Zone B GoogleMaps . MV 222424, cranial part L coracoid preserved from the mid shaft ( Fig. 4E View Figure 4 ), Lake Pinpa , (location code MV No. 2348), Namba Formation, Pinpa LF .
Together these specimens show the following: acrocoracoid not pneumatic, dorsoventral plane of acrocoracoid aligned nearly at right angles to plane of sternal end; both dorsal and ventral lobes of clavicle facet extensively overhang supracoracoidal sulcus; ventral clavicle facet does not overhang ventral shaft facies; supracoracoidal sulcus not excavated below humeral facet; scapular cotyla large and oval; procoracoid lacks a foramen; dorsal surface of the blade without pneumatic fossa; ventral facies flat; and ventral sternal facet present but not prominent of the ventral facies.
These coracoids are very similar to those referred to Pi. tedfordi and Pi. vickersrichae , but are smaller than both. Among extant taxa, SAM P.41301 is most similar to coracoids of Nettapus pulchellus and Mal. membranaceus , although it is smaller. It is more similar to Malacorhynchus and differs from Nettapus in the shape of the humeral facet, which is widest at about mid-length (not widest and rounded towards acrocoracoidal end as in Nettapus ). Similarly, MV 222424 is very similar to both Pi. tedfordi and Malacorhynchus in the form of the clavicle facet that extensively overlaps the supracoracoidal sulcus.
Measurements: SAM P.41301 – estimated total medial length = 27 mm, SW = 3.2 mm; MV 222424 – length scapular cotyla-head = 8.3 mm; SW = 2.9 mm; length humeral facet = 6.0 mm.
Scapula: SAM P.42673, L scapula, Billeroo Creek , Site 2 , 31° 06.205 ′ S; 140° 13.912 ′ E, Namba Formation, Pinpa LF, measurements – width acromion to humeral facet = 6.7 mm, shaft height = 2.2 mm.
Small anatid scapula, shaft with parallel dorsal and ventral margins, acromion not directed dorsally from shaft, coracoidal articulation globose and prominent, humeral facet laterally orientated.
Tibiotarsus: AMNH 10953 About AMNH , pL tibiotarsus, Lake Pinpa , Site C, Namba Formation, Pinpa LF, measurements – preserved length = 9.0 mm , PW = 5.8 mm. SAM P.42678, dL tibiotarsus with broken lateral condyle, Billeroo Creek , Site 2, 31° 06.205 ′ S 140° 13.912 ′ E, Namba Formation, Pinpa LF, measurements – SW = 2.5 mm GoogleMaps .
These specimens are smaller than those referred to Pi. tedfordi , but have a similar morphology. They reveal that the medial and lateral articular facets of the proximal end have a similar depth (rather than the medial one extending markedly caudad of the lateral one), and that they are separated caudally by a distinct notch. The structure of the cnemial crests is not determinable.
Tarsometatarsus: AMNH 10838, worn dR tarsometatarsus, Lake Pinpa, Site C, Namba Formation, Pinpa LF, measurements – DW = c. 6.0 mm.
This specimen is referred to Anatidae as it lacks a fossa metatarsi I (metatarsal fossa) and the plantar exit for the distal foramen opens in a groove into the lateral intertrochlear notch, and is referred on size to Pi. fromensis . Trochlea metatarsal II does not extend distad of the lateral intertrochlear notch.
SUBFAMILY TADORNINAE REICHENBACH 1849 –1850:
SHELDUCKS
The following taxon is referred to the tadornines as the humerus has the following characters: (1) proportions as in Tadorna ; (2) elevated and elongate dorsal tubercle; (3) capital shaft ridge directed at area between dorsal tubercle and head; (4) dorsal pneumotricipital fossa narrow, not excavated under head; (5) ventral pneumotricipital fossa large, more than half proximal width, wider than long, pneumatic; (6) the osseous lamella extending from the caudal shaft surface around the distal margin of the ventral pneumotricipital fossa merges with the bicipital crest/ base of fossa in ventral half of fossa; (7) deltoid crest dorsally concave; (8) facet for anterior ligament elevated, directed distally; (9) scapulotricipital sulcus a distinct groove caudally, extends around distal end; (10) distinct ectepicondylar prominence; (11) flexor process equal distal extent to dorsal condyle;
Character 1 is derived in tadornines with Anseranas , dendrocygnines, and anserines plesiomorphic with an elongate humerus. Character 3 is derived in tadornines relative to Anseranas and anserines where the ridge is directed towards the head. Character 5 is derived in tadornines with Anseranas , dendrocygnines, and anserines relatively plesiomorphic with a narrow fossa. Character 6 is considered an apomorphy of tadornines with the plesiomorphic state of the lamella remaining elevated from the floor of the fossa and extending up under the ventral tubercle in Anseranas , dendrocygnines, and anserines: anatines are more derived with the lamella merging with the floor of the fossa in the dorsal part of the fossa. Character 7 and the elevated dorsal tubercle are retained plesiomorphic features that distinguish tadornines from anatines that have derived states (deltoid crest convex or flat dorsally; dorsal tubercle not elevated off adjacent facies). Character 8 is derived relative to the unelevated state in Anseranas or the low elevation of the facet in anserines. Character 10 is a retained plesiomorphy with the prominence most developed in the tadornines ( Miotadorna, Alopochen ) that distinguishes tadornines from the anatines in which it is apomorphically lost.
Humeri of Anseranas differ greatly, for example, more elongate; capital shaft ridge directed towards the head; a relatively small ventral pneumotricipital fossa largely occluded by a broad osseous lamella extending from the caudal shaft surface; short flexor process; no scapulotricipital groove caudally or distally; and facet for anterior ligament not elevated. Those of anserines, geese and swans, are more elongate; the osseous lamella extending from the caudal shaft surface into the ventral pneumotricipital fossa remains elevated off the base of the fossa and extends up under the ventral tubercle; and the capital shaft ridge is directed towards the head. Dendrocygna species are all smaller; the dorsal tubercle is near circular; the osseous lamella extending from the caudal shaft surface into the ventral pneumotricipital fossa is as in anserines; and the ventral pneumotricipital fossa is small, much less than half proximal width. Humeri of the oxyurines, Biziura , Oxyura , and Malacorhynchus differ in several ways but all have a closed or nonpneumatic ventral pneumotricipital fossa. Stictonetta , apart from the smaller size, differs with the capital shaft ridge directed towards the dorsal tubercle and so has a wider dorsal pneumotricipital fossa. All anatines differ by the derived loss of the capital shaft ridge and loss of elevation of the dorsal tubercle, and by the dorsal surface of the deltoid crest being flat or convex.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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