Dinosaur Dolphins Survived In New Zealand Long After Extinction Elsewhere – Canterbury Museum

Dinosaur dolphins survived in Aotearoa New Zealand waters long after they went extinct elsewhere. They had begun evolving into whales before eventually dying out, research into a North Canterbury fossil has discovered.

Icthyosaurs, marine reptiles that looked like dolphins, largely went extinct 100 million years ago. Canterbury Museum Senior Curator Natural History Dr Paul Scofield and University of Canterbury master’s graduate George Young spent 3 years studying a 4-metre-long fossil discovered in North Canterbury. The findings were recently published in the Journal of Vertebrate Paleontology.

They concluded that Aotearoa New Zealand was home to a unique ichthyosaur that managed to survive for 5 million years after its peers around the world went extinct. The fossil is the most completely preserved ichthyosaur discovered in Aotearoa New Zealand and one of the youngest ichthyosaur fossils ever found.

Paul and George used medical scanners to penetrate concrete-hard rocks and create three dimensional images of the fossilised bones hidden inside. The analysis revealed the ichthyosaur was evolving from a reptile into something more like a whale, Paul said.

“It had lost its pelvis and become more like a whale or a dolphin. This specimen represents the last gasp of evolution for the icthyosaur.

“Ultimately, their prolonged presence in Aotearoa may allow us to solve the riddle of why they became extinct around the world.”

The fossil was discovered by Professor James Crampton of Victoria University Wellington near Coverham at the northern end of Clarence River Valley in North Canterbury in 2010. Even though it is the most complete ichthyosaur fossil ever found in Aotearoa, it is only a partial specimen.

“It’s a new member of the ichthyosaur club, but it is not complete enough to give it a name,” Paul said.

The fossil is distinct from other ichthyosaurs discovered in Australia. It has a smaller pelvis bone than other fossils found around the world. Paul and George were able to date the fossil to 95 million years ago by analysing the layer of rock where it was discovered.

“It was in the right layer and the fossils around it were of known ages.”

Paul said the high country where the fossil was discovered is very poorly explored and could yield more groundbreaking discoveries.

Icthyosaurs, which grew up to 26 metres long, first appear in the fossil record from around 250 million years ago, surviving until about 95 million years ago. Complete fossilised skeletons of the marine reptiles were first discovered in England in the 1830s.

Icthyosaur fossils were first discovered in Aotearoa by Canterbury Museum founder Julius von Haast in 1861 near Mt Potts at the top of the Rangitata River.