Nelepsittacus: a small radiation of Miocene New Zealand parrots

Nelepsittacus was a genus of parrots from the early Miocene St Bathans fauna of New Zealand, about 19–16 million years ago. Its original description assigned 85 bones to three named species and noted two more that may represent an unnamed fourth form. Shoulder and limb anatomy links the genus with the nestor parrots, the group that includes living kākā and kea. The fossils support a diverse native parrot lineage, but do not preserve the birds’ colours, calls or exact foods. The extinct bird catalogue includes Nelepsittacus among New Zealand’s fossil island birds.

Quick facts

A parrot radiation at St Bathans

Trevor Worthy, Alan Tennyson and Richard Scofield described Nelepsittacus in 2011 from the St Bathans fauna of Central Otago, on New Zealand’s South Island. The fossils come from the early Miocene Bannockburn Formation and associated deposits, broadly dated to about 19–16 million years ago. St Bathans is the first substantial pre-Quaternary terrestrial vertebrate fauna known from New Zealand.

The authors described three species from 85 fossils: 17 specimens assigned to N. minimus, 60 to N. donmertoni and six to N. daphneleeae. Two additional fossils may represent a fourth, unnamed taxon. These are separate bone specimens, not 85 skeletons or 85 individual birds. Their uneven representation also means that the species are not equally well known.

The smallest named species, N. minimus, was around the size of small living parakeets. N. donmertoni is represented by the largest sample and spans a larger size range. N. daphneleeae is less well represented, so its anatomy and variability are less securely characterised. A single composite “Nelepsittacus” should not erase those distinctions.

How the fossils were assigned

The fossil material includes coracoids, humeri, tibiotarsi and tarsometatarsi, among other bones. These elements preserve useful anatomical characters even when they are not joined into a complete skeleton. The researchers compared the fossils with living and fossil parrots and identified character combinations that distinguish the three species.

Features of the coracoid, humerus, tibiotarsus and tarsometatarsus support a relationship with Nestor, the genus that includes the kea and kākā. The analysis placed Nelepsittacus within the nestorine branch and away from the kakapo line, Strigops. The result is a phylogenetic inference from anatomy. It does not establish that one named Nelepsittacus species directly gave rise to the kea or kākā.

The name Nelepsittacus alludes to Nestor, but a shared name element is not a taxonomic argument. The relationship rests on the bones. Future fossils with skulls, beaks or more complete skeletons could refine how the extinct genus fits among nestor parrots.

Flight and feeding

The known wing bones retain the proportions of a flying parrot. Nothing in the described material indicates the severe wing reduction seen in some island birds that became flightless. Powered flight is therefore a well-supported interpretation, though no fossil measures how far the birds travelled or how they moved through the forest canopy.

Parrots often eat seeds, fruit, flowers, buds and other plant material, but this comparison is not a direct record of the Miocene species’ diet. The original sample does not provide secure gut contents, a diagnostic food bolus or enough complete beak material to establish a specialist. It is safer to describe plant feeding as plausible and the exact menu as unknown.

The fauna also includes Heracles inexpectatus, a much larger parrot described from two incomplete tibiotarsi. Its estimated mass of about seven kilograms makes it distinct from the smaller Nelepsittacus species. The coexistence of these forms indicates that St Bathans supported several parrot lineages and sizes, not a single island parrot gradually growing larger through time.

Lake forests and a changing Zealandia

The St Bathans deposits preserve evidence of a lake system with forested shores, wetlands and streams. Fish, crocodilians, turtles, bats and many birds occur in the same broad fauna. The bird fossils accumulated in sediments that capture the surrounding terrestrial ecosystem; they do not prove that every animal lived at the lake edge.

These parrots lived after the late Oligocene period of high sea levels, when some reconstructions propose that much of Zealandia was submerged. Their presence contributes to evidence that parts of the New Zealand landmass remained available to terrestrial life or were recolonised. The fossils alone cannot show a continuous, uninterrupted population history through the entire interval.

Central Otago is now much cooler and drier than the early Miocene setting. Modern vegetation should not be copied as a literal background. Forest structure, plant communities and climate have changed substantially since the bones were deposited.

What an illustration can and cannot show

The fossil evidence supports small to medium nestorine parrots that could fly and differed in size. It does not preserve their feather colours, exact crest or tail shapes, calls, flock behaviour or nesting habits. Bright green, red or blue plumage may make a vivid illustration, but no pigment-bearing feather has been found for the genus.

Nor should a reconstruction show Nelepsittacus as an oversized kakapo or as a direct miniature version of the kea. The skeletal record supports evolutionary affinity, not identity of behaviour. An image of a parrot among early Miocene vegetation is therefore a reasoned scene built around fossil dimensions and a documented environment, with the finer details left as artistic choices.

Unlike the flightless Anomalopteryx, Nelepsittacus retained a wing suited to powered flight. The comparison is useful for illustrating how different New Zealand birds adapted to island settings, but their lineages and ecologies were distinct.