Sansom’s plover was described from six bones recovered from 19-16 million-year-old (Early Miocene) lake-bed deposits along the Manuherikia River and Mata Creek, St Bathans, Central Otago.

The holotype (NMNZ S.52628, a partial left coracoid) is held at Museum of New Zealand Te Papa Tongarewa (Te Papa). Five additional skeletal elements tentatively referred to this species are held at Te Papa (4) and Canterbury Museum (1).

Sansom’s plover was a small, sheathbill-like wader that was between a banded dotterel and a New Zealand dotterel in size (i.e. about 95 g). It is relatively rare in the St Bathans deposits, and the few fragments found are insufficient to deduce much about the bird’s leg length, flying ability and ecology. Some elements found were not skeletally mature, indicating that the birds bred locally, rather than being migrants from elsewhere. The depositional environment was an inland lake, suggesting that they foraged on the lake shore.

Skeletal features place Sansom’s plover basal to a clade that includes both the sheathbills (Chionidae) of the Antarctic Peninsula and subantarctic islands in the Atlantic and Indian Oceans, and the Magellanic plover (Pluvianellidae) of South America. Although much smaller than the two species of living sheathbills, features of the coracoid in particular point to Sansom’s plover being more similar to a sheathbill than to a Magellanic plover. However, the combination of features shared with either or both Chionidae and Pluvianellidae preclude referral to either family. All are placed within the super-family Chionoidea in the sub-order Charadrii.

The mosaic of features found in Sansom’s plover supports the split between Magellanic plover and sheathbills being more recent than 19-16 million years ago. Molecular data also indicate that the split between these two groups was among the most recent for family level divergence within Charadrii. Other examples of New Zealand faunal connections with South America include our mystacinid bats (with South American noctilionids), and Coenocorypha snipes (with Andean, cordilleran and imperial snipes).

The genus name is after Neilus who in Greek mythology was the father of Chiona, alluding to Sansom’s plover being basal to sheathbills in the genus Chionis. Neilus derives from the Greek word meaning ‘river valley’ and so it also describes the site where the fossils were found.  The species name honours Southland ornithologist Olga Sansom (1900-1989) who, along with her daughter Maida Barlow, undertook studies of shorebirds in southern New Zealand.

Weblink

Te Ara

References

De Pietri, V.L.; Scofield, R.P.; Hand, S.J.; Tennyson, A.J.D.; Worthy, T.H. 2016. Sheathbill-like birds (Charadriiformes: Chionoidea) from the Oligocene and Miocene of Australasia. Journal of the Royal Society of New Zealand 46: 181-199.

Recommended citation

Miskelly, C.M. 2016 [updated 2017]. Sansom’s plover. In Miskelly, C.M. (ed.) New Zealand Birds Online.