''Miotadorna'' is a genus of

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

tadornine

duck Duck is the common name for numerous species of waterfowl in the family (biology), family Anatidae. Ducks are generally smaller and shorter-necked than swans and goose, geese, which are members of the same family. Divided among several subfam ...

s from the

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

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 preserve ...

ised right

humerus The humerus (; : humeri) 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 (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

collected from the Saint Bathans Fauna, in the lower Bannockburn Formation of the Manuherikia Group, found by the Manuherikia River in the

Central Otago Central Otago is an area 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 ...

region of the

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

. 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 biolog ...

''. The specific

epithet An epithet (, ), also a byname, is a descriptive term (word or phrase) commonly accompanying or occurring in place of the name of a real or fictitious person, place, or thing. It is usually literally descriptive, as in Alfred the Great, Suleima ...

refers to the fossil sites’ location in the vicinity of the historic gold mining town of Saint Bathans, 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 precisely 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 a ...

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