Jurassic Beetle: CSIRO Entomologist Discovers Living Fossil

September 28, 1998

CSIRO entomologist Dr John Lawrence admits it was a thrill: the delicate bronze-and-white spiny beetle glittering in the light of his microscope was a living fossil, whose ancestral roots go back almost 200 million years.

"The peculiar look of the animal caught my eye straight away. The unique combination of spines, scales and lack of wings. At first I was puzzled, then I realised it was an ommatid, a member of a family of beetles which dates back to the Jurassic," he recounts.

The beetle, a fresh candidate for the honour of oldest living Australian, is even more ancient than the super-continent Gondwana. Its cousins are found in South America, North America, Europe and Asia, suggesting they originated at the time when all of the earth's contintents formed one vast landmass, known as Pangaea.

The beetle is from the family Omma, and its species is entirely new to science. So far, only two specimens have been discovered, from different sites in the South Australian Mallee, at Calperum-Bookmark Biosphere Reserve and Brookfield Conservation Park.

"We had set up flight-intercept traps to catch flying insects. Below them was a small trough into which the insects fell. This trough sometimes catches flightless animals too, when they walk into it."

That was how the two specimens of the new Omma species came to stumble into the entomological record books.

"We know next to nothing about them, because they are so rare," Dr Lawrence says. "There are a couple of related species which have been found in eastern Australia, and one specimen of an ommatid larva, from Perth."

The Ommatidae are members of the Archostemata, one of the four great suborders which make up the vast order of beetles (Coleoptera). The Archostemata are regarded as the most primitive and ancient.

Fossil relatives of the living beetles discovered in the Mallee have been found in Jurassic rocks of Siberia, Central Asia and Britain. The Jurassic was between 210 and 145 million years ago.

Dr Lawrence says the antiquity of this particular beetle is evident in the presence of certain body parts which, in modern beetles, have either fused with other parts or disappeared altogether.

Its appearance is quite curious: a strongly mottled bronze-brown and white body, covered in stout spikes protruding from its body scales. This contrasts markedly with other, smoother members of the Omma clan, and Dr Lawrence considered describing it as a new genus, rather than a species.

"Generally speaking, the ommatids are a group that has always been able to survive in marginal habitats, in the drier parts of the continent. They bore into rotten wood and old mallee roots, so they are probably important to the process of breaking down old wood and maintaining the fertility of the soil."

Dr Lawrence says it is impossible to say whether the new Omma species has escaped discovery until now because it is extremely rare - or simply because it tends to spend much of its time underground. But it is living proof that Australia still harbours an enormous wealth of ancient animals and plants which remain unknown and undiscovered.

"After the discovery of the Wollemi pine, near Sydney, I'd expect to find anything anywhere," he says.

In fact, Dr Lawrence adds wistfully, it would be interesting to study the insects that have survived on the Wollemi pine itself. There must be a few more Jurassic-era specimens there for the finding too. But so far, the trees' location remains a close-held botanical secret.

CSIRO Australia

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