Waipatiidae Fordyce, 1994

Fitzgerald, Erich M. G., 2016, A late Oligocene waipatiid dolphin (Odontoceti: Waipatiidae) from Victoria, Australia, Memoirs of Museum Victoria 74, pp. 117-136 : 119-129

Waipatiidae Fordyce, 1994

Gen. et sp. indet.

“…a primitive eurhinodelphinid odontocete.” ( Fitzgerald, 2004:

184)

Referred material. NMV P48861, incomplete skeleton consisting of: nine isolated teeth; fragments of one cervical and 12 thoracic vertebrae; parts of 16 ribs; left incomplete scapula, humerus, radius, ulna, two metacarpals, and phalanx; right (fragmentary) scapula, humerus, radius, ulna, metacarpal, and phalanx; and fragments of two presumed carpals plus three phalanges ( Figs. 2–11 ; Tables 1–2). Collected by Thomas H. Rich and Ian Stewart, 1976.

Locality. Shore platform in intertidal zone, immediately north of Bird Rock (a prominent stack), western end of Jan Juc Beach, Jan Juc, Victoria, southeast Australia; near latitude 38° 20' 58" S, longitude 144° 18' 10" E ( Fig. 1 ) .

Horizon and age. NMV P48861 was collected as a single large block (dimensions ~850×520× 300 mm) of massive light grey friable silty sandy glauconitic marl forming the lowermost ~ 2 m of the Jan Juc Marl exposed at Bird Rock (Unit BR 1 in Section 4 of Abele, 1979: 23–25) ( Fig 1 ). The sparse associated macrofossils include molluscs ( Dosinia , Limopsis chapmani , Notocallista , Ennucula , cf. Tellina , and Turritellidae indet.: T. A. Darragh, pers. comm. 3 July 2015), bryozoans ( Otionellina and cf. Lunulites rutella : R. Schmidt, pers. comm. 3 July 2015), and teleost fish bones.

Although planktonic foraminifera are rare in the Jan Juc Marl and rarely age-diagnostic ( Li et al., 1999), maximum and minimum age constraints are available. 40 Ar/ 39 Ar dating of Angahook Formation basalts underlying the Point Addis Limestone (laterally equivalent to the Jan Juc Marl) at Aireys Inlet gave an age of 28.7 ± 0.2 Ma ( McLaren et al., 2009). The oldest age of the Jan Juc Marl based on 87 Sr/ 86 Sr ratios measured in brachiopods from the lowest 3 m of the Bird Rock section is 27.2 Ma ( McLaren et al., 2009). Sphenolithus ciperoensis occurs in the basal beds of the Jan Juc Marl at Bird Rock, marking the base of calcareous nannofossil zone NP24 and therefore an age of <29.62 Ma ( Siesser, 1979; Gradstein et al., 2012). Together, these data suggest the Jan Juc Marl in outcrop is no older than the Rupelian–Chattian boundary, 28.1 Ma ( McLaren et al., 2009).

The contact between the Jan Juc Marl and conformably overlying Puebla Clay has long been considered to approximate the Oligocene–Miocene boundary ( Abele, 1979; Li et al., 1999; McLaren et al., 2009). Zygrhablithus bijugatus is absent from the top ~ 2.5 m of Jan Juc Marl in the Bird Rock section ( Siesser, 1979), its last appearance datum within calcareous nannofossil zone NP25 at 23.76 Ma ( Gradstein et al., 2012). Siesser (1979) also reported the last occurrence of Reticulofenestra bisecta about 1 m below the Jan Juc Marl/Puebla Clay contact; the last appearance datum of this species marking the top of zone NP25 at 23.13 Ma ( Gradstein et al., 2012). The first appearance datum of Discoaster druggi marks the boundary between calcareous nannofossil zones NN1 and NN2 (22.82 Ma), and this species is first recorded in the beds above the Jan Juc Marl/ Puebla Clay contact ( Siesser, 1979; Gradstein et al., 2012) ( Fig. 1 ). The planktonic foram Globoquadrina dehiscens , the first occurrence of which marks the base of zone M1b (22.44 Ma) in southern Australia, is first recorded in the basal Puebla Clay ( Li et al., 1999; McGowran et al., 2004; Gradstein et al., 2012). The evidence from biostratigraphy shows that the Jan Juc Marl/ Puebla Clay contact is between 23.13 and 22.82 Ma, straddling the Oligocene–Miocene boundary at 23.03 Ma ( McLaren et al., 2009) ( Fig. 1 ). This is corroborated by 87 Sr/ 86 Sr ratios from the basal Puebla Clay, which give a range of possible ages from 23.89–21.39 Ma ( McLaren et al., 2009).

The age of the exposed Jan Juc Marl is therefore most rigorously constrained to between about 28.10 and 22.82 Ma, Chattian to earliest Aquitanian. NMV P48861 was collected from the lowest beds in the Bird Rock section of the Jan Juc Marl, stratigraphically below the last occurrence of Zygrhablithus bijugatus , which has a last appearance datum of 23.76 Ma ( Fig. 1 ). This constrains the age of NMV P48861 to between about 28.1 and 23.7 Ma, and therefore within the Chattian.

Diagnosis. An odontocete with: heterodont dentition including at least one pair of procumbent apical teeth and small double-rooted posterior cheek teeth with triangular crowns bearing two or three posterior denticles; a small rod-like coracoid process of the scapula; an elongated humerus bearing a strongly salient deltoid tuberosity continuous with a distally-elongated crest, and a distal end that is distinctly narrower (anteroposteriorly) than the proximal end of the shaft; a long and anteroposteriorly narrow radius bearing a transversely thin crest on its anterior edge; and a well-developed hatchet-shaped olecranon of the ulna. None of these characters represent unambiguous synapomorphies of Waipatiidae , but this combination of characters is found only in taxa assigned to that clade (see Comparisons below).

Remarks on Platanistoidea . The concept of Platanistoidea used here is that of Muizon (1987) with emendments by Fordyce (1994) and Tanaka and Fordyce (2015a); namely that Platanistoidea includes the living family Platanistidae plus the extinct clades Squalodelphinidae , Waipatiidae , Otekaikea , and Squalodontidae . This definition and taxonomic content of Platanistoidea has been questioned ( Lambert et al., 2014: 988): some recent analyses posit both Squalodontidae and Waipatiidae as stem odontocetes ( Geisler et al., 2011, 2014; Lambert et al., 2014, 2015; Sanders and Geisler, 2015); or platanistoids ( Murakami et al., 2012; Tanaka and Fordyce,2015a);or exclude squalodontids from Platanistoidea , but include Waipatiidae in the latter ( Tanaka and Fordyce, 2014). The taxonomic content and phylogenetic position of Squalodontidae (and the potentially related Prosqualodon ) are enduring problems in cetacean systematics recently reviewed by Tanaka and Fordyce (2014: 27). Their hypothesis for the content of Squalodontidae is followed here. For reviews of the taxonomic content and phylogenetic position of other putative platanistoid clades (i.e. Allodelphinidae , Dalpiazinidae ) see Muizon (1988, 1991, 1994), Fordyce (1994), Barnes (2006), Barnes and Reynolds (2009), and Lambert et al. (2014).

Figures

Figure 1. Locality map and stratigraphic section of the locality of NMV P48861, Waipatiidae gen. et sp. indet. Dates in bold text are based on measured 87Sr/86Sr ratios in McLaren et al. (2009). Planktonic foraminiferal and calcareous nannofossil stratigraphy, and geochronology are based on Gradstein et al. (2012). Planktonic foraminiferal data from Li et al. (1999), and calcareous nannofossil data from Siesser (1979). The measured section at Bird Rock is based on McLaren et al. (2009).

Figure 2. The original distribution of elements in matrix prior to preparation, NMV P48861, Waipatiidae gen. et sp. indet. Top, block of matrix enclosing bones as collected in field, prior to preparation. Bottom, tracing of bone outlines in matrix prior to preparation.

Figure 3. Anterior teeth I–III of NMV P48861, Waipatiidae gen. et sp. indet. Tooth I, presumed procumbent incisor in: A, labial; B, anterior; C, posterior; and D, lingual views. Tooth II, anterior tooth in: E, posterior; F, labial; G, anterior; and H, lingual views. Tooth III, right upper anterior tooth in: I, labial; J, posterior; K, anterior; and L, lingual views. Specimens whitened with ammonium chloride.

Figure 4. Right upper anterior/anterior cheek teeth IV–VI of NMV P48861, Waipatiidae gen. et sp. indet., in labial (A, E, I), lingual (B, F, J), anterior (C, G, K), and posterior (D, H, L) views. A–D: tooth IV. E–H: tooth V. I–L: tooth VI. Specimens whitened with ammonium chloride.

Figure 5. Upper cheek teeth VII–IX of NMV P48861, Waipatiidae gen. et sp. indet., in labial (A, E, I), lingual (B, F, J), anterior (C, G, K), and posterior (D, H, L) views. A–D: tooth VII, left upper anterior cheek tooth. E–H: tooth VIII, right upper posterior cheek tooth. I–L: tooth IX, right upper posterior cheek tooth. See Material and Methods for abbreviations. Specimens whitened with ammonium chloride.

Figure 6. Ribs of NMV P48861, Waipatiidae gen. et sp. indet. in anterior view. 1: first right rib. 2: second left rib. 3: third left rib.

Figure 7. The left forelimb bones of NMV P48861, Waipatiidae gen. et sp. indet. in lateral view. A: scapula. B: humerus. C: radius. D: ulna. Specimens whitened with ammonium chloride.

Figure 8. Scapulae of NMV P48861, Waipatiidae gen. et sp. indet. Left scapula in: A, medial; and B, distal views. C: glenoid region of right scapula in medial view. Specimens whitened with ammonium chloride.

Figure 9. Humeri of NMV P48861, Waipatiidae gen. et sp. indet. Left humerus in: A, medial; B, anterior; C, posterior; and D, proximal views. Right humerus in: E, lateral; and F, medial views. Specimens whitened with ammonium chloride.

Figure 10. Radius and ulnae of NMV P48861, Waipatiidae gen. et sp. indet. A: left radius in anterior view. B: right ulna in anterior view. C: right ulna in medial view. D: left ulna in posterior view. Specimens whitened with ammonium chloride.

Figure 11. Metacarpals and phalanx of NMV P48861, Waipatiidae gen. et sp. indet. A: left metacarpal. B: left metacarpal. C: right metacarpal. D: left phalanx in lateral view. Specimens whitened with ammonium chloride.