Daily BulletinDaily Bulletin

The Conversation

  • Written by James D. Holmes, Palaeontology PhD student, University of Adelaide

At up to 30cm long and armed with spines for crushing and shredding food, we’ve identified a previously unknown creature that would have been a giant among its neighbours in the waters off modern-day South Australia.

The newly described fossil of a trilobite – known as Redlichia rex – is detailed in a paper out this week in the Journal of Systematic Palaeontology.

There is even evidence this monster of the ancient sea could have been a cannibal, feeding on its own kind.

Read more: Curious Kids: are humans going to evolve again?

Trilobites are related to modern-day crustaceans (such as crabs and lobsters) and insects, and are some of the oldest animals to appear in the fossil record.

Because of their abundance, trilobites are considered a model group for understanding the Cambrian explosion – the sudden appearance about 540 million years ago of almost all major animal groups on Earth.

Trilobites first appeared around 520 million years ago and lasted for about 270 million years.

A giant species of trilobite inhabited Australian waters half a billion years ago An illustration of the Cambrian seafloor with the trilobite Redlichia rex in the foreground. Katrina Kenny, Author provided

Exceptional fossil deposits

Our most important understanding of life around the time of the Cambrian explosion comes from a series of rare, exceptional fossil deposits called Konservat-Lagerstätten (German for “conservation storage-place”).

These deposits preserve not only the hard parts of organisms such as shells, but also the soft parts such as eyes, muscles and guts. The most famous of these is the Burgess Shale from Canada, although a number of other similar deposits have been discovered in places such as China and Greenland.

Australia also boasts one of these deposits – the only one in the Southern Hemisphere. It is called the Emu Bay Shale and is found on Kangaroo Island in South Australia.

The most common fossils within the Emu Bay Shale are trilobites.

The latest find

In our study, we describe a very large new trilobite from the Emu Bay Shale. It’s one of the largest trilobites known from the Cambrian Period.

A giant species of trilobite inhabited Australian waters half a billion years ago A large specimen of the newly described trilobite Redlicha rex from the Emu Bay Shale compared to a 20c coin. James Holmes/University of Adelaide, Author provided

Due to its exceptional size and armament, we decided Redlichia rex would be an appropriate name. This is reminiscent of the name Tyrannosaurus rexrex means “king” in Latin. The Redlichia part of the name is the genus (the same as Homo in Homo sapiens), originally named in 1902 after palaeontologist Karl Redlich.

Because the Emu Bay Shale preserves the soft parts of organisms, we find the appendages (or legs) of trilobites preserved as well as the hard shell. These soft parts are extremely rare – complete appendages are known for only six of the more than 20,000 described species.

What is even more special about the Emu Bay Shale examples is that because Redlichia rex was so big, the appendages are also very large, making them easier to look at in detail.

A giant species of trilobite inhabited Australian waters half a billion years ago A graphic reconstruction of the Redlichia rex appendage used for shredding and crushing prey. Katrina Kenny, Author provided

The most important feature of these is an enlarged inner side of the base of each pair of legs, which was covered in short, robust spines and worked as a nutcracker.

Carnivores of the sea

Unlike those of other trilobites, the morphology of the spines suggests they may have been adapted to crushing shells of other Cambrian animals. If this were the case, the most likely food Redlichia rex would have been eating was other trilobites.

In the Emu Bay Shale, we also find what are called coprolites, or fossilised poo. In these we find pieces of crushed-up trilobite.

A giant species of trilobite inhabited Australian waters half a billion years ago Crushed-up pieces of trilobite were found in the coprolites, the fossilised poo. James Holmes, Author provided

It was originally thought poo fossils such as these were produced by the giant Cambrian predator Anomalocaris – a metre-long beast with two strange claws in the head and a circular, vampire-toothed mouth. But it now seems likely that Redlichia rex produced some of these.

Consistent with this idea, some specimens of Redlichia rex show injuries resulting from attack. These may also be from Anomalocaris, although it is possible that Redlichia rex indulged in cannibalism, or took part in territorial battles (as is seen in modern lobsters).

Read more: Life quickly finds a way: the surprisingly swift end to evolution's big bang

Once animals began to eat each other, the selective pressure to adapt methods to prevent being eaten would have been very high. This is almost certainly the reason why hard shells evolved in the Cambrian – for protection against predation.

Lobsters caught battling it out today.

The result would have been an evolutionary arms race between predators and prey, with each developing more efficient ways of defence and attack, such as the development of shell-crushing abilities in certain animals.

The formidable appendages of Redlichia rex are probably a result of this, and this giant trilobite was likely a source of terror for small creatures on the Cambrian seafloor.

Authors: James D. Holmes, Palaeontology PhD student, University of Adelaide

Read more http://theconversation.com/a-giant-species-of-trilobite-inhabited-australian-waters-half-a-billion-years-ago-118452

We need to Close the Gap on health. But even official dietary advice disadvantages Indigenous people


'It is not easy': how science and courage saved the stunning Australian Alps


The Conversation


Did BLM Really Change the US Police Work?

The Black Lives Matter (BLM) movement has proven that the power of the state rests in the hands of the people it governs. Following the death of 46-year-old black American George Floyd in a case of ...

a Guest Writer - avatar a Guest Writer

Scott Morrison: the right man at the right time

Australia is not at war with another nation or ideology in August 2020 but the nation is in conflict. There are serious threats from China and there are many challenges flowing from the pandemic tha...

Greg Rogers - avatar Greg Rogers

Prime Minister National Cabinet Statement

The National Cabinet met today to discuss Australia’s COVID-19 response, the Victoria outbreak, easing restrictions, helping Australians prepare to go back to work in a COVID-safe environment an...

Scott Morrison - avatar Scott Morrison

Business News

Reinventing The Outside Of Your Office

Efficient work is a priority in most offices. You need a comfortable interior that is functional too. The exterior also affects morale. Big companies have an amazing exterior like university ca...

News Company - avatar News Company

Kaspersky and Ferrari partnership: tailoring cybersecurity for an iconic brand

Kaspersky is commemorating the 10 year anniversary of its strategic partnership with iconic, global brand - Ferrari. The cybersecurity company is a sponsor of the brand’s Formula One racing team...

News Company - avatar News Company

Instant Steel Solutions Review

Are you keen on having the right guidance, knowledge and information about the right kind of steel purchases for your industries? If yes, then you are in the right place. There is no doubt that ...

a Guest Writer - avatar a Guest Writer

News Company Media Core

Content & Technology Connecting Global Audiences

More Information - Less Opinion