Fossils of Giant Crab Unearthed in New Zealand

Paleontologists have described a new species of the crab genus Pseudocarcinus from large-sized fossilized specimens found at Taranaki, North Island, New Zealand.

Pseudocarcinus is a monotypic genus in the crab family Menippidae.

It includes a very large species called the Tasmanian giant crab (Pseudocarcinus gigas).

Also known as the giant southern crab, it resides on rocky and muddy bottoms off Southern Australia.

“The living ‘southern giant crab’ Pseudocarcinus gigas ranks amongst the largest crabs ever to have lived,” said Utrecht University paleontologist Barry van Bakel and his colleague Àlex Ossó.

“At present, it is endemic to the cool-temperate southern Australian continental margin, although there is also a single record of a female individual caught off the South Island of New Zealand.”

“Scientists recognised and described the unique morphological character set of this monotypic genus and erected a new family and superfamily to accommodate it.”

“Unfortunately, the geological history of this remarkable group of crabs is poorly known.”

Named Pseudocarcinus karlraubenheimeri, the new member of the genus lived in New Zealand around 8.8 milion years ago (Miocene epoch).

Six specimens of the species were collected from Waitoetoe Beach in the Urenui Formation of the Taranaki Basin, in which a series of volcanoes of the Mohakatino Volcanic Centre erupted offshore, leading to the formation of a specific paleoenvironment.

“This is the first evidence that Pseudocarcinus inhabited the region that is now New Zealand,” the researchers said.

According to the team, Pseudocarcinus males have one normal-sized and one oversized claw.

“In modern seas, crabs have larger absolute claw sizes in temperate regions than they do in tropical regions, although claws are smaller relative to body size in temperate seas,”

“The Miocene of New Zealand supported two species of giant crab with the largest crushing claws known: Tumidocarcinus giganteus and Pseudocarcinus karlraubenheimeri.”

“Apparently, food sources, metabolic conditions and calcium-carbonate supply were favourable for these species.”

“Tumidocarcinus became extinct by the end of the Miocene; Pseudocarcinus is currently known only from Australian waters.”

The team’s paper was published in the New Zealand Journal of Geology and Geophysics.