Lavanttalornis hassleri, Bochenski & Happ & Salwa & Tomek, 2023

Bochenski, Zbigniew M., Happ, Johannes, Salwa, Grzegorz & Tomek, Teresa, 2023, An intriguing new species of dabbling duck (Aves: Anseriformes) from the middle Miocene of Austria, Palaeontologia Electronica (a 52) 26 (3), pp. 1-19 : 5-12

Lavanttalornis hassleri sp. nov.

Figures 1 , 2 , 3 A-E, 4, 5A, 6A zoobank.org/ 9E7230E3-FC50-4AE6-987B-E1F0DD6C7C95

Etymology. The species is named after the finder of the specimen, Dr. Andreas Hassler of Sankt Andrä, a veterinarian by profession but a paleontologist by passion.

Holotype. LMK-Pal 7453a+a’+b+c+d ( Figures 1 , 2 , 3 A-E, 4, 5A, 6A), partly articulated nearly complete skeleton on four slabs from which the right coracoid has been removed, cleaned and is visible as a 3D object; housed at the paleontological collection of the Landesmuseum Kärnten (LMK-Pal), Klagenfurt, Austria.

Type locality and horizon. A site near the village of Schassbach , about 50 km northeast of Klagenfurt in the Lavanttal, Carinthia, southern Austria. GPS coordinates using WGS 84 datum: 46.79752°N 14.80676°E at an altitude of 471 m above sea level. The specimen is dated to the Upper Sarmatian s. s. (upper middle Miocene), ca 12 Ma. It was found in freshwater sediments that contain two coal seams lying above the Middle Sarmatian layers ( Reischenbacher et al., 2007) .

Diagnosis. As for the genus.

Measurements. Measurements (in mm) including total length (TL) and others, taken from slabs A, B or C: coracoid (A, dext) TL, 47.6, medial length, 42.4, sternal width, 17.7; scapula (A, sin) articular height, 11.2; humerus (A, sin) TL, 75.5, proximal width, 18.7, distal width, 10.6, least shaft width, 6.3; radius (B, dext) TL, 62.6; ulna (B, dext) TL, 69.5; carpometacarpus (B, dext) TL, 46.4, proximal width, 11.9; phalanx proximalis dig. majoris (B, dext) TL, 19.6; phalanx dig. minoris (B, dext) TL=9.6; pelvis (C) TL, 64.4, width between antitrochanters, 30.5.

Description and Comparison

Skull. The skull, visible in lateral view on slabs C and D, is partly an imprint and partly fossilized bone remains ( Figures 2 , 6A ). As in Mionetta blanchardi , the length of the beak is approximately the same as that of the skull. The braincase is too damaged for meaningful comparisons which also applies to the preserved small fragment of ramus mandibulae. As in extant anseriforms, the foramina neurovascularia are visible at the end of the beak. The caudal part of the nostril is elongated and tapered, while in the Miocene Mioquerquedula sp. , Bambolinietta lignitifila and extant anseriforms, the caudal part of the nostril is rounded.

Coracoid. The well-preserved right coracoid removed from slab A ( Figures 1 , 3 A-E) shows a very thick, massive shaft that is somewhat similar to that of the Miocene Anas kurochkini , Mionetta blanchardi and extant Anas , Spatula , Mareca , and Melanitta ; Mionetta natator and extant species of the genera Aythya , Bucephala , and Mergus have much slender shafts. A feature specific to Lavanttalornis hassleri is the medial margin of the omal section of the shaft, which is strongly inclined medially and almost straight. In Chenoanas , medial margin of shaft is also straight but it does not incline medially, whereas in Mionetta blanchardi , Mionetta consobrina , Mionetta natator , Aix praeclara , Mioquerquedula minutissima , Mioquerquedula soporata , Anas kurochkini , Pinpanetta , Manuherikia , Dunstanetta , Protomelanitta velox , and most extant taxa (e.g., Aix , Anas , Spatula , Mareca , Aythya , Clangula , Melanitta ) the medial margin of shaft is much less medially inclined, and is usually slightly arched. As, for example, in the extant genus Anas s.l., the ventral plane of the processus acrocoracoideus is subparallel to the ventral plane of the extremitas sternalis ( Worthy and Lee, 2008: character 45). The processus acrocoracoideus hardly protrudes beyond the medial margin of the shaft. This distinguishes it from the genera Chenoanas and Pinpanetta , Matanas enrighti , Aix praeclara , Mioquerquedula minutissima , Mioquerquedula soporata , Protomelanitta velox , Mionetta consobrina , Mionetta natator , and to a lesser extent from Mionetta blanchardi and many extant taxa (e.g., Aix , Anas , Mareca , Spatula , Clangula ). The tuberculum brachiale (name by Zelenkov and Kurochkin, 2012; Zelenkov and Panteleyev, 2015) is concave and slightly wider dorsoventrally than craniocaudally high. As in extant species of the genus Anas but unlike the extinct Anas kurochkini , the crista acrocoracoidea (name by Elzanowski et al., 2012) is thick. As in all anatids, the margin of the facies articularis humeralis projects laterally, although not as far as in Anas kurochkini , and in lateral view it has an acute cranial angle. The sulcus m. acrocoracoidei is deeply excavated near the facies articularis humeralis, which is observed in taxa from various groups. As in many ducks, the processus proccoracoideus is relatively short, projecting craniomedially, and the cotyla scapularis is deeply concave of a rounded-triangular shape. The angulus medialis is short, blunt ended, and its short cranial edge is almost perpendicular to the shaft; in Mionetta blanchardi the angulus medialis merges with the shaft gradually, in Pinpanetta a distinct flange of various shape extends cranially along the medial shaft margin, and in Protomelanitta velox , Manuherikia , and Miotadorna sanctibathansi the angulus medialis is acute. In ventral view, the edge of the facies articularis sternalis is almost straight, whereas in Mionetta blanchardi , Mionetta natator , Anas kurochkini , Mioquerquedula minutissima , Manuherikia lacustrina , and Miotadorna sanctibathansi it arches sternally.

Scapula. Articular parts with small fragments of the shaft of the left and right scapula are visible on slab A in medial (costal) view; slab B has an imprint of the right scapula ( Figures 1 , 4A ). As in Mionetta blanchardi and some extant taxa (e.g., Anas acuta , A.platyrhynchos , Spatula quercquedula , S. clypeata , Melanitta fusca ), the acromion deviates very slightly dorsally; its dorsal edge forms an almost straight line with the margo dorsalis of the corpus scapulae. In many other species (e.g., Aix galericulata , Anas crecca , Mareca strepera , Aythya ferina , A.fuligula , Clangula hyemalis , Bucephala clangula , Mergellus albellus ), the acromion is much more dorsally curved.

Humerus. The left humerus is visible on slab A in cranial view and the right humerus in cranioventral view. Slab B shows an imprint of the dorsocaudal side of the right bone with a preserved tuberculum ventrale ( Figures 1 , 4 A-C, F). As in the Miocene Aythya denesi , the notch of incisura capitis in proximal outline of the humerus is shallow ( Worthy and Lee, 2008: character 59) whereas in the late Oligocene Pinpanetta from Australia as well as in extant dendrocygnines, anserines and tadornines it is (almost) missing. The notch is more pronounced in Mionetta blanchardi , Sharganetta mongolica , Nogusunna conflictoides , Protomelanitta gracilis , Aythya molesta , A. shihuibas , Manuherikia , and Dunstanetta . Extant species of such genera as Aix , Anas , Spatula , Mareca , Aythya , Melanitta , or Mergellus also show a more pronounced notch. The tuberculum ventrale is directed caudo-cranially so its distal margin is approximately at right angles to the fossorial plane ( Worthy and Lee, 2008: character 57). A similarly directed tuberculum ventrale is found in Pinpanetta , Aythya shihuibas and Aythya denesi , whereas in Miotadorna sanctibathansi , Mionetta , and the genus Chenoanas , the tuberculum ventrale is proximally oriented. As in extant Aix galericulata , Anas crecca , Spatula clypeata , Spatula querquedula , the tuberculum ventrale is narrow (forms a narrow ridge); the tuberculum is wide in many other extant taxa including Anas platyrhynchos , Anas acuta , Aythya ferina , Aythya fuligula , Bucephala clangula , Clangula hyemalis , Melanitta . The length of the crista deltopectoralis is comparable with the proximal width of the humerus. Other details of the crista deltopectoralis as well as details of the remaining structures of the proximal humerus, including tuberculum dorsale, crista bicipitalis, fossa pneumotricipitalis and capital shaft ridge, are not visible. As in Pinpanetta fromensis , Pinpanetta vickersrichae and Mionetta blanchardi the shaft is relatively thick, and it does not narrow distally but its sides are essentially parallel to each other ( Worthy and Lee, 2008: character 61). The humerus of Bambolinetta lignitifila was definitely even more robust and stouter. In Aythya denesi , Manuherikia and Dunstanetta , Pinpanetta tedfordi and the similarly sized extant species, the shaft narrows distally. The shaft is s-shaped, in dorsal view. A similarly bent shaft is found in many extant taxa, including Aix galericulata , Anas crecca , Anas acuta , Anas platyrhynchos , Mareca strepera , Mareca penelope , Spatula clypeata , Spatula querquedula , Bucephala clangula , and Clangula hyemalis . In contrast, the shaft is more straight in such species as Aythya fuligula or Mergellus albellus . As in Mionetta , Manuherikia , Dunstanetta , Malacorhynchus , Stictonetta , Nomonyx , and Pinpanetta , the facet of the tuberculum supracondylare ventrale (attachment of the anterior articular ligament) is cranially buttressed ( Worthy and Lee, 2008: character 65), whereas the unbuttressed facet is observed in Anseranas , Thalassornis , Biziura , and Oxyura . Moreover, in Lavanttalornis hassleri , the facet is tilted distally. As in Miocene Mionetta blanchardi and extant species such as Aix galericulata or Aythya fuligula , but unlike e.g., Spatula clypeata , fossa m. brachialis (brachial fossa) is large, well-defined and forms a marked depression ( Worthy and Lee, 2008: character 68). It differs from that in Pinpanetta , where it is elongate and dorsal margin barely extends past midshaft width. As in Mionetta blanchardi , the processus flexorius extends roughly as far distally as condylus dorsalis ( Worthy, 2009: character 63). As in Miocene Mionetta blanchardi and Sharganetta mongolica , and extant Anatinae , there is no prominent tuberculum supracondylare dorsale (ectepicondylar prominence) ( Worthy and Lee 2008, character 64). A distinct ectepicondylar prominence is present in the Miocene Pinpanetta as well as in extant anserines. Contrary to Mionetta blanchardi , Pinpanetta , Miotadorna sanctibathansi , Sharganetta mongolica , Nogusunna conflictoides , and Protomelanitta gracilis , the distal end of the humerus is little expanded ventrally, and the condylus ventralis is roundish (more oblong in Mionetta , Pinpanetta , and Sharganetta but also roundish in Protomelanitta and Miotadorna ).

Ulna. The right ulna is visible on plate A in ventral view, and its imprint is on plate B. The bone is clearly less stout and relatively longer than that of Bambolinetta lignitifila . Its length is in the range of Mionetta blanchardi ; ulna of M. consorbina was longer, and that of M. natator was shorter. The proximal and distal parts are crushed, preventing meaningful comparisons.

Radius. The right proximal radius is visible on plate B in anterior view, and its distal posterior side is imprinted there. Plate A shows the distal right radius with a large portion of shaft in posterior view, and an imprint of the anterior proximal part ( Figures 1 , 4 F-G). The bone differs significantly from that of Bambolinetta lignitifila , from which it is clearly less stout and relatively longer. As in Mionetta blanchardi , the shaft is more straight than, for example, in extant Spatula clypeata . As in Spatula clypeata , the capital tuberosity (name used by Howard, 1929) is roundish but clearly larger than in Spatula , whereas in some other extant species, such as Aythya ferina or Melanitta nigra the tuberculum is more oval. As in Mionetta blanchardi and Spatula clypeata , the tuberculum aponeurosis ventralis is proximodistally relatively short, whereas in some extant species, such as Clangula hyemalis or Melanitta fusca the tuberculum is significantly longer.

Carpometacarpus. The right carpometacarpus is visible on slab B in dorsal view, and its imprint is preserved on slab A. Moreover, the distal part of the left bone is visible on slab D in dorsal view ( Figures 2 , 4D ). As in Mionetta blanchardi and such modern taxa as Anas , Spatula , Mareca or Bucephala , the processus extensorius is broad proximodistally and a distinct arcuate indentation separates it from the processus alularis; in Clangula hyemalis , the indentation is very small. Also as in Mionetta blanchardi and such extant taxa as Aix galericulata , Anas acuta , Anas crecca , A. platyrhynchos , Spatula clypeata , Spatula querquedula , Mareca penelope , Mareca strepera , Aythya fuligula , and A. ferrina , the symphysis metacarpalis distalis is long in relation to the carpometacarpus width measured just distad of spatium intermetacarpale ( Worthy and Lee, 2008: character 84). The symphysis is relatively shorter in many other species (e.g., Bucephala clangula , Clangula hyemalis , Melanitta fusca , M.nigra , Mergellus albellus . There is a distinct nodule in the distal dorsal side of the os metacarpale majus. A similar nodule is in extant Anas platyrhynchos , Anas acuta , Anas crecca , Mareca penelope , Mareca strepera , Spatula querquedula , Spatula clypeata , Aythya fuligula , Aythya ferina , and Clangula hyemalis . In Bucephala clangula , Melanitta fusca , M.nigra , Mergus merganser , Mergus serrator the nodule is small or absent.

Phalanx proximalis digiti majoris. The right phalanx, detached from the carpometacarpus, is visible on slab B in dorsal view, and its imprint is preserved on slab A ( Figures 1 , 5 ). For a duck, the phalanx is relatively wide in relation to its length, which is the result of a bulging of the caudal edge. In this respect, it differs from Mionetta blanchardi and most extant duck species whose phalanx is narrower and its caudal and cranial edges are often almost parallel to each other. One of the few taxa with a similarly wide phalanx is Anas platyrhynchos , but other members of the Anatini , such as Spatula clypeata , have narrower phalanges. A broad phalanx is also found e.g., in Aix galericulata of uncertain systematic affiliation. In the proximal part of the phalanx there is a nodule clearly raised both above the dorsal surface and the pila cranialis. A similar nodule is found in species of the genus Anas s.l. Other modern ducks either do not have such a nodule, or if they do, it is less pronounced, especially in relation to pila cranialis.

Pelvis. Pelvis is visible on slab C in dorsal view, and its imprint is preserved on slab D ( Figures 2 , 6 ). The overall proportions of the pelvis, that is, length to width between antitrochanters and to width of the ala preacetabularis ilii, are similar to that of Anas platyrhynchos ; some of the extant genera, e.g., Netta , Aythya , Oxyura or Biziura have a much narrower pelvis. Mionetta blanchardi also had a narrower pelvis, especially for ala preacetabularis ilii. Also as in Anas platyrhynchos , Spatula clypeata or Aix gallericulata , the pre-acetabular and post-acetabular parts are of similar length. In Aythya , Netta , Oxyura , Bucephala , or Biziura , the post-acetabular region is elongated to varying degrees. As in Mionetta blanchardi and many extant taxa including Aix , Anas , Aythya , Bucephala , and Melanitta , the caudal edges of the ala ischii and ala postacetabularis ilii extend roughly equally far caudally; in Dendrocygna , the ala ischii reaches further caudally. As in all Anatidae , foramina intertransversaria can be discerned.

Femur. Portions of the left and right femur are visible on slab C, and their imprints are on slab D. The bones are too damaged to allow meaningful comparisons.

Tibiotarsus. The distal part of the right tibiotarsus is visible on slab D in anterolateral view and its imprint is on slab C. Portions of the left tibiotarsus and their imprints are on both slabs ( Figures 2 , 4E ). As in Mionetta blanchardi and extant Anatidae , the condylus medialis projects much medially in relations to distal shaft and the lateral side of distal shaft forms a sharp edge that slants anteriorly towards condylus lateralis ( Bochenski and Tomek, 2009: characters 7a, 7b and 14’b). The pons supratendineus is located in the middle of the shaft and opens into the incisura intercondylaris, which is also typical of anseriforms. In contrast to the Miocene genus Chenoanas , the lateral margin of the condylus lateralis is medially inclined (in Chenoanas , it is positioned in line with the lateral margin of the shaft), and condyli lateralis and medialis are proximodistally long (in Chenoanas , the condyli are shorter than the width of the incisura intercondylaris).

Ratios between selected skeletal elements. For Lavanttalornis hassleri , the brachial index (humerus length/ulna length) is 1.1; similar values of this ratio are also observed in some extant species in all other groups of Anatinae (Appendix 1). Slightly lower values (approx. 1.0) are typical for all Dendrocygninae and parts of Tadornini , and slightly higher values (approx. 1.2) occur in various groups. The ratio humerus length/carpometacarpus length for Lavanttalornis hassleri is 1.6, and similar values were most often recorded in extant Anatini (in 15 species out of 20 examined) and in several species of Mergini , Tadornini and genera incertae sedis. It is true that higher values of this ratio (1.7--2.2) were recorded in some species among all taxonomic groups examined, but only in Dendrocygninae , Oxyurinae , and Aythyni, i.e., in the groups of good divers, all species showed these higher values. The ratio of carpometacarpus length/coracoid medial length for Lavanttalornis hassleri is 1.1, and similar values were recorded in most of the examined Anatini (12 species out of 18), and most of the examined species of uncertain taxonomic position (incertae sedis: 7 out of 10). Again, the most homogeneous groups with different values of this ratio than in Lavanttalornis were Dendrocygninae and Tadornini , in which all species showed higher values (1.2--1.4). In other species that dive for food, including Aythyni (4 out of 5), Mergini (6 out of 9) and Oxyura jamacensis , these values were lower (0.9--1.0).

Figures

FIGURE 1. Lavanttalornis hassleri gen. et sp. nov., holotype, specimen LMK-Pal 7453a+b from Lavanttal, Austria, middle Miocene. A, slab A after exposing all the bones and removing the coracoid; B, slab B (counterslab of the wing bones visible on slab A); C, fragment of slab A before removal of the coracoid. Abbreviations: lcs, left scapula; lhu, left humerus; rcm, right carpometacarpus; rco, right coracoid; rcs, right scapula; rhu, right humerus; rmin, right phalanx digiti minoris; rpda, right phalanx digiti alulae; rpdm, right phalanx proximalis digiti majoris; rra, right radius; rul, right ulna. Scale bar equals 10 mm.

FIGURE 2. Lavanttalornis hassleri gen. et sp. nov., holotype, specimen LMK-Pal 7453c+d from Lavanttal, Austria, middle Miocene. A, slab C; B, slab D (counterslab of slab C). Abbreviations: lcm, left carpometacarpus; lfe, left femur; ltb, left tibiotarsus; pel, pelvis; rfe, right femur; rtb, right tibiotarsus; sku, skull; ver, vertebrae. Scale bar equals 10 mm.

FIGURE 3. Comparison of the right coracoid. A–E, Lavanttalornis hassleri gen. et sp. nov., holotype, specimen LMK- Pal 7453a’ from Lavanttal, Austria, middle Miocene (removed from slab A) in ventral, dorsal, lateral, medial and dorsomedial views; F–G, Dendrocygna bicolor (Dendrocygninae); H–I, Oxyura jamacensis (Oxyurinae); J–K, Melanitta nigra (Anatinae: Mergini); L–M, Aix galericulata (incerte sedis); N–O, Aythya fuligula (Anatinae: Aythyni); P–R, Anas platyrhynchos (Anatinae: Anatini); S–T, Tadorna tadorna (Anatinae: Tadornini). Extant specimens are shown in ventral (left) and dorsal (right) views. Abbreviations: agm, angulus medialis; csc, cotyla scapularis; car, crista acrocoracoidea; fah, facies articularis humeralis; fas, facies articularis sternalis; pac, processus acrocoracoideus; ppc, processus procoracoideus; sac, sulcus m. acrocoracoidei; tbr, tuberculum brachiale. Scale bars equal 10 mm.

FIGURE 4. Lavanttalornis hassleri gen. et sp. nov., holotype, specimen LMK-Pal 7453a+b+d from Lavanttal, Austria, middle Miocene. A, proximal left humerus in cranial view and proximal left scapula in medial view (preserved on slab A); B, proximal right humerus in dorsocaudal view (preserved on slab B); C, distal left humerus in cranial view (preserved on slab A); D, right carpometacarpus in dorsal view (preserved on slab B); E, distal right tibiotarsus in anterolateral view (preserved on slab D); F, right proximal radius in anterior view (preserved on slab B); G, right distal radius in posterior view (preserved on slab A). Abbreviations: acr, acromion; cdd, condylus dorsalis; cdv, condylus ventralis; cla, condylus lateralis; cme, condylus medialis; ctu, capital tuberosity; fbr, fossa m. brachialis; fts - facet of the tuberculum supracondylare ventrale (attachment of the anterior articular ligament); ica, incisura capitis; ini, incisura intercondylaris; oma, os metacarpale majus; pal, processus alularis; pex, processus extensorius; pfl, processus flexorius; psu, pons supratendineus; se, sharp edge; syd, symphysis metacarpalis distalis; tav, tuberculum aponeurosis ventralis; tdo, tuberculum dorsale; tve, tuberculum ventrale. Scale bar equals 10 mm.

FIGURE 5 (to right). Comparison of the right phalanx proximalis digiti majoris in dorsal view. A, Lavanttalornis hassleri gen. et sp. nov., holotype, specimen LMK-Pal 7453b from Lavanttal, Austria, middle Miocene (preserved on slab B); B, Dendrocygna bicolor (Dendrocygninae); C, Oxyura jamacensis (Oxyurinae); D, Melanitta nigra (Anatinae: Mergini); E, Tadorna ferruginea (Anatinae: Tadornini); F, Aythya ferrina (Anatinae: Aythyni); G, Anas platyrhynchos (Anatinae: Anatini); H, Spatula clypeata (Anatinae: Anatini); I, Aix galericulata (incerte sedis). The phalanges of extant species are shown in the same size as the fossil phalanx to facilitate comparison. Abbreviations: pcr, pila cranialis. Scale bars equal 10 mm.

FIGURE 6. A, skull and pelvis of Lavanttalornis hassleri gen. et sp. nov., holotype, specimen LMK-Pal 7453c from Lavanttal, Austria, middle Miocene (preserved on slab C); B, pelvis of Anas platyrhynchos (Anatinae: Anatini); C, pelvis of Aythya fuligula (Anatinae: Aythyni). Abbreviations: ant, antitrochanter; fin, foramina intertransversaria; isc, ala ischii; nos, nostril; poi, ala postacetabularis ilii; pri, ala preacetabularis ilii; ram, ramus mandibulae (inside surface of right branch). Scale bars equal 10 mm.