''Miotadorna'' is a genus of

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

tadornine

duck Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form t ...

s from the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

of New Zealand. It contains two species, ''M. sanctibathansi'', and ''M. catrionae'' (Catriona's shelduck).

''M. sanctibathansi''

''M. sanctibathansi'' was described from a

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

ised right

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

collected from the

Saint Bathans Fauna The St Bathans fauna is found in the lower Bannockburn Formation of the Manuherikia Group of Central Otago, in the South Island of New Zealand. It comprises a suite of fossilised prehistoric animals from the late Early Miocene (Altonian) period, ...

, in the lower Bannockburn Formation of the

Manuherikia Group The Manuherikia Group is a fluvial- lacustrine sedimentary fill in the Central Otago area of New Zealand, at the site of the prehistoric Lake Manuherikia. The area consists of a valley and ridge topography, with a series of schist-greywacke mountai ...

, found by the

Manuherikia River The Manuherikia River is located in Otago in the South Island of New Zealand. It rises in the far north of the Maniototo, with the West Branch draining the eastern side of the St Bathans Range, and the East Branch draining the western flanks of t ...

in the

Central Otago Central Otago is located in the inland part of the Otago region in the South Island of New Zealand. The motto for the area is "A World of Difference". The area is dominated by mountain ranges and the upper reaches of the Clutha River and tributa ...

region of the

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

. The genus name reflects the view of the describers that the bird is a Miocene shelduck similar to those in the genus ''

Tadorna The shelducks, most species of which are found in the genus ''Tadorna'' (except for the Radjah shelduck, which is now found in its own monotypic genus ''Radjah''), are a group of large birds in the Tadorninae subfamily of the Anatidae, the biologi ...

''. The specific

epithet An epithet (, ), also byname, is a descriptive term (word or phrase) known for accompanying or occurring in place of a name and having entered common usage. It has various shades of meaning when applied to seemingly real or fictitious people, di ...

refers to the fossil sites’ location in the vicinity of the historic gold mining town of

Saint Bathans St Bathans, formerly named Dunstan Creek, is a former gold and coal mining town in Central Otago, New Zealand. The settlement was a centre of the Otago Gold Rush, but mining has since long ceased. It is now largely a holiday retreat due to the p ...

, of which it is a latinisation.

''M. catrionae''

''M. catrionae'', described and named in 2022, is the largest duck species so far discovered in the St Bathans fossil deposits. Both the species name, ''catrionae'', and the common name, Catriona's shelduck, honour co-author Nicholas J. Rawlence's late mother Catriona Drummond. The holotype specimen is a large right humerus. It is noted as being very similar to ''M. sanctibathansi'', but its large size and differing proportions distinguish it from that species. This size difference may represent sexual dimorphism, although the morphological changes are not sufficiently explained by this. Worthy ''et al''., (2022) considered ''M. catrionae'' to be a

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of ''M. sanctibathansi'', as they believed it was more likely that the larger specimen represented a larger sex.

References

Fossil taxa described in 2007 Birds described in 2007 Tadorninae Miocene birds Extinct birds of New Zealand {{Paleo-bird-stub