Extinct Duck Discovered In New Zealand Could Help In Dating Other Finds: New Study

A newly discovered extinct duck that lived in ancient Aotearoa could help researchers narrow down dates for other finds from an ancient lake bed, according to a new study.

Artist's impression of a duck in the Manuherikia genus. Credit: Tom Simpson/Canterbury Museum

New Delhi: A newly discovered extinct duck that lived in ancient Aotearoa could help researchers narrow down dates for other finds from an ancient lake bed, according to a new study. Aotearoa is the current Maori (one of the original people of New Zealand and the Cook Islands) name for New Zealand. 

The study describing the new bird was recently published in the peer-reviewed journal, Geobios. 

The Bird Was A Small Diving Duck

The new species is a small diving duck researchers have named Manuherikia primadividua. The bird lived between 16 and 19 million years ago on a huge paleolake (lake that existed in the past) called Lake Manuherikia, according to the study. This ancient lake bed has been uncovered in St Bathans, Central Otago, New Zealand. The extinct duck could be key to dating other finds from the ancient lake bed.

Why Is M. primadividua Special?

According to the study, M. primadividua is the first animal found at St Bathans that could help researchers date other finds at the lake, a statement issued by Canterbury Museum in New Zealand said. The St Bathans Fauna is a highly diverse non-marine vertebrate assemblage derived from the lower Miocene, the geological epoch which occurred from about 23.03 to 5.333 million years ago, according to the study.

M. primadividua Replaced Another Duck

Associate Professor Trevor Worthy of Flinders University, Adelaide, the lead author of the study, said that the duck appears to have replaced another related duck species, Manuherikia lacustrina, according to the statement.

This occurred at some point in the three-million-year period preserved in the fossil record at St Bathans. Worthy said that the researchers have not found these two ducks in the same fossil layer, and they think that is because the ducks lived at different times. 

Competition Between Two Ducks

Manuherikia primadividua outcompeted its older cousin, and eventually replaced it, Worthy said.

He added that the switch in duck species may well occur at the same time as a change in the vegetation in the region. Pollen studies conducted years ago had revealed this. 

Worthy said that if so, this may be evidence of climate change affecting the St Bathans Fauna.

According to the statement, Dr Paul Scofield, one of the co-authors of the study, said that the two ducks will allow many of the other finds from St Bathans to be dated.

How M. primadividua Could Help Date Newly Discovered Species

If researchers find a new species alongside M. lacustrina fossils, they will know the species lived in the earlier period, according to Scofield. If a new species is found alongside the newly discovered bird, it would imply that the new species lived a bit later. This allows researchers to start putting all the animals they have found at St Bathans in some sort of chronological order for the first time, Scofield said.

The discovery of the duck underpins the importance of knowing exactly which layer a fossil derives from, according to the study.

Scofield said that the dead duck is an important step in building up a picture of how the animals and plants living on the ancient lake uncovered in St Bathans changed over time. 

Fossils of marine animals are relatively common in New Zealand, compared to the remains of ancient land-based animals, which are extremely rare.

According to the study, the ancient lake bed preserved at the St Bathans site is the most significant known deposit of land-based animal fossils in New Zealand.

Since 2001, excavations have been ongoing at St Bathans. More than 40 ancient bird species have been unearthed as a result of these excavations. 

The authors noted in the study the remains of waterfowl which are deposited in paleolake Manuherikia dominate the avian assemblage. There are eight known species of waterfowl in four genera. Manuherikia primadividua is the fourth species in the genus.

Other animals discovered include bats, turtles, and a crocodile. These findings completely changed what was known about the evolution of New Zealand's fauna, the researchers said in the statement.

Why Was The Newly Discovered Bird Named So?

Palaeontologists gave the species name 'primadividua' to acknowledge that the duck provides the first evidence of a chronological division in the St Bathans fauna.

Canterbury Museum and the Museum of New Zealand Te Papa Tongarewa hold the Manuherikia primadividua fossils.

The researchers said in the study a relatively minor environmental change towards drier and more seasonal climates appeared to have driven the palaeoecological replacement of M. lacustrina by M. primadividua in Manuherikia.