Matuku otagoense, Scofield & Worthy & Tennyson, 2010

Scofield, R. Paul, Worthy, Trevor H. & Tennyson, Alan J. D., 2010, A Heron (Aves: Ardeidae) from the Early Miocene St Bathans Fauna of Southern New Zealand, Records of the Australian Museum 62 (1), pp. 89-104 : 93-95

Matuku otagoense n.sp.

Holotype. NMNZ S.50003: Distal end, shaft and lateral proximal edge of left tarsometatarsus with fragmentary lateral cotyla and basal hypotarsus; the three trochlea are preserved but the distal foramen is obscured; the medial proximal end is missing. The bone was already fragmented in situ when discovered and has subsequently been repaired in the laboratory ( Figs 1 , 2 ). It was collected on 9 January 2007 during a University New South Wales, NSW, Australia / University of Adelaide , South Australia/ Canterbury Museum, Christchurch, NZ/Museum of New Zealand Te Papa Tongarewa, Wellington, NZ, expedition.

Diagnosis. As for genus.

Etymology otagoense, Latin , after Otago province in southern New Zealand, where the excavations take place; gender neuter, conforming to the gender of the generic name.

Type locality. Home Hills Station , Site HH 4, true left side Manuherikia River , Otago, New Zealand. 44° 54.472'S 169° 51.434'E. NZMS 260 H41/618843, New Zealand Fossil Record File Number H 41/f0095. The site was first exposed by river erosion between February 2005 and March 2006 . Bones were recovered from the site in March 2006 and January 2007.

Stratigraphy/Age/Fauna. Bannockburn Formation, Manuherikia Group, Early Miocene (Altonian); 19–16 Ma; St Bathans Fauna. HH4 is a 5–15 cm thick clay-silt layer notable for the large number of shell fragments of the gastropod Glyptophysa . It is located 2.15–2.35 m above the top of an obvious oncolite layer and 25.63–25.83 m above base of Bannockburn Formation.

Measurements of holotype. See Table 3.

Paratypes. NMNZ S.51264. Distal end of tarsometatarsus, missing distal end of all three trochlea (HH1b Trench excavation, 15 January 2008) ; NMNZ S.50004. Cranial end of right coracoid, broken approximately half way down shaft (HH1a, 8 January 2007) ; NMNZ S.50852. Left quadrate missing entire proc. orbitalis (HH4, 8–16 January 2008) ; NMNZ S.50854. Left quadrate missing entire proc. orbitalis (HH1a, 15 January 2008) ; NMNZ S.50853. Axis with damage to caudal end of proc. caudalis (HH4, 8–16 January 2008) ; NMNZ S.51174. Tip of mandible including most of mandibular symphysis, but with damage to tip (HH1b trench excavation, 14 January 2008) .

Tarsometatarsus (NMNZ S.51264, not illustrated).

In its exterior appearance, this fragmentary element does not differ significantly in any way from NMNZ S.50003. The exceptional preservation of the distal foramen in this specimen, however, allows us to see a feature that can not be discerned in NMNZ S.50003. In NMNZ S.51264, the dorsal opening of the foramen does not open into the intertrochlear incision but is separated from it, by a thin lamella giving the foramen three openings, one dorsally, one opening to the incision and one plantarly. This feature appears to be a feature the fossil shares only with Syrigma and Botaurus amongst the ardeids examined.

Differential diagnosis of tarsometatarsi

Figures

Figure 1. Specimens of the fossil heron Matuku otagoense. Scale bar is 1 cm. Right coracoid, extremitas omalis, paratype of Matuku otagoense, S.50004, HH1a, in medial (A) and lateral (B) aspects; left tarsometatarsus, holotype of Matuku otagoense, S.50003, HH4, in plantar (C) and dorsal (D) aspects; and referred axis vertebra S.50853, HH4, in cranial (E) and left lateral (F) aspects.Abbreviations:fac, clavicular facet, facies articularis clavicularis; smc, supracoracoidal sulcus, sulcus musculi supracoracoidei; ridge, character 23 “Slight ridge running sternally, barely dividing sulcus into two segments”; pa, acrocoracoid, processus acrocoracoideus; fah, humeral facet, facies artic. humeralis; ila, impression for the acrocoracohumeralis ligament, impressio ligamentum acrocoracohumeralis; bt, brachial tuberosity; p, procoracoid, proc. procoracoideus; cpl, crista plantaris lateralis; fm1, fossa metatarsal I; imm, Incisura intertrochlearis medialis; tm3, trochlea metatarsi III; po, dens, processus odontoideus; fcr, cranial facies of articulation, facies articularis cranialis; zcr, prezygapophysis, zygapophysis cranialis; fca, caudal facies of articulation, facies artic. caudalis; zca, postzygapophysis, zygapophysis caudalis; pv, hypapophysis, proc. ventralis corporis; fp, pneumatic foramen, foramen pneumaticum; ps, spinous process, proc. spinosus; ft, transverse foramen, foramen tranversarium.

Figure 2. Referred specimens of the fossil heron Matuku otagoense. Scale bar is 1 cm. Left quadrate (S. 50852; HH4): (A) caudal aspect; (B) rostral aspect; (C) lateral aspect; (D) medial aspect; (E) ventral aspect. Abbreviations: o, capitulum oticum; ic, vallecula intercapitularis; s, capitulum squamosum; ct, crista tympanica; c, condylus caudalis; pt, condylus pterygoideus; pm, processus medialis; m, condylus medialis; l, condylus lateralis; pl, processus lateralis; cm, crista medialis; cl, crista lateralis; or, processus orbitalis; fb, fossa basiorbitalis; pf, facies pterygoidea; dp, depression praecondylaris; qj, cotyla quadratojugalis; fm, foramen pneumaticum mediale; in, vallecula intercondylaris; t on dp, tubercle on depressio praecondylaris.