Reconstructions show how some of the earliest animals lived—and died (w/ Video)

Aug 11, 2014
This is a paleontological reconstruction of rangeomorph fronds from the Ediacaran Period (635-541 million years ago). These species are from the deep-marine Avalon Assemblage (approximately 575-560 million year ago) known from fossil sites in Canada and the UK, and some are also known from later Ediacaran assemblages. These reconstructions were built using computer models of rangeomorph growth and development. Credit: Jennifer Hoyal Cuthill (University of Cambridge).

A bizarre group of uniquely shaped organisms known as rangeomorphs may have been some of the earliest animals to appear on Earth, uniquely suited to ocean conditions 575 million years ago. A new model devised by researchers at the University of Cambridge has resolved many of the mysteries around the structure, evolution and extinction of these 'proto animals.' The findings are reported today in the journal PNAS.

Rangeomorphs were some of the earliest large organisms on Earth, existing during a time when most other forms of life were microscopic in size. Most rangeomorphs were about 10 centimetres high, although some were up to two metres in height.

These creatures were ocean dwellers which lived during the Ediacaran period, between 635 and 541 million years ago. Their bodies were made up of soft branches, each with many smaller side branches, forming a geometric shape known as a fractal, which can be seen in many familiar branching shapes such as fern leaves and even river networks.

Rangeomorphs were unlike any modern organism, which has made it difficult to determine how they fed, grew or reproduced, and therefore difficult to link them to any particular modern group. However, despite the fact that they looked like plants, evidence points to the fact that rangeomorphs were actually some of the earliest animals.

"We know that rangeomorphs lived too deep in the ocean for them to get their energy through photosynthesis as plants do," said Dr Jennifer Hoyal Cuthill of Cambridge's Department of Earth Sciences, who led the research. "It's more likely that they absorbed nutrients directly from the sea water through the surface of their body. It would be difficult in the modern world for such large animals to survive only on dissolved nutrients."

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An animation of the growth and development of the extinct rangeomorph species Beothukis mistakenis, which lived during the Ediacaran Period from approximately 575 to 555 million years ago. Credit: Jennifer Hoyal Cuthill (University of Cambridge).

"The oceans during the Ediacaran period were more like a weak soup – full of nutrients such as organic carbon, whereas today suspended food particles are swiftly harvested by a myriad of animals," said co-author Professor Simon Conway Morris.

Starting 541 million years ago, the conditions in the oceans changed quickly with the start of the Cambrian Explosion – a period of rapid evolution when most major animal groups first emerge in the fossil record and competition for nutrients increased dramatically.

Rangeomorphs have often been considered a 'failed experiment' of evolution as they died out so quickly once the Cambrian Explosion began in earnest, but this new analysis shows just how successful they once were.

Rangeomorphs almost completely filled the space surrounding them, with a massive total surface area. This made them very efficient feeders that were able to extract the maximum amount of nutrients from the ocean water.

This is a paleontological reconstruction of rangeomorph fronds from the Ediacaran Period (635-541 million years ago). These species are from the deep-marine Avalon Assemblage (approximately 575-560 million years ago) known from fossil sites in Canada and the UK, and some are also known from later Ediacaran assemblages. These reconstructions were built using computer models of rangeomorph growth and development. Credit: Jennifer Hoyal Cuthill (University of Cambridge).

"These creatures were remarkably well-adapted to their environment, as the oceans at the time were high in nutrients and low in competition," said Dr Hoyal Cuthill. "Mathematically speaking, they filled their space in a nearly perfect way."

Dr Hoyal Cuthill examined rangeomorph fossils from a number of locations worldwide, and used them to make the first computer reconstructions of the development and three-dimensional structure of these organisms, showing just how well-suited they were to their Ediacaran environment.

As the Cambrian Explosion began however, the rangeomorphs became 'sitting ducks', as they had no known means of defence from predators which were starting to evolve, and the changing chemical composition of the ocean meant that they could no longer get the they required to feed.

"As the Cambrian began, these Ediacaran specialists could no longer survive, and nothing quite like them has been seen again," said Dr Hoyal Cuthill.

Explore further: Study shows size matters in prehistoric seas

More information: Fractal branching organizations of Ediacaran rangeomorph fronds reveal a lost Proterozoic body plan, Proceedings of the National Academy of Sciences, www.pnas.org/cgi/doi/10.1073/pnas.1408542111

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User comments : 11

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supamark23
5 / 5 (2) Aug 11, 2014
my first thought on seeing them, "hmm, look a bit like a sponge precursor." Sort of an inside-out sponge.
betterexists
1 / 5 (4) Aug 11, 2014
Dinosaurs were GIANTS. How did they survive? By Eating/Swallowing Air?
What happened to the GIGANTIC TREES of Those Times?
Funny! Were they capable of Photosynthesis by themselves?
malapropism
5 / 5 (8) Aug 11, 2014
Dinosaurs were GIANTS. How did they survive? By Eating/Swallowing Air?
What happened to the GIGANTIC TREES of Those Times?
Funny! Were they capable of Photosynthesis by themselves?

What has your apparently totally non-sequitur comment to do with the article? The rangeomorph organisms studied existed way before the time of the dinosaurs (before even the Cambrian explosion, as is stated in the article), they were all quite modest in size (10cm - 2m) and they existed in deep marine environments. And anyway, not all dinosaurs were giants.
Whydening Gyre
5 / 5 (6) Aug 11, 2014
Dinosaurs were GIANTS. How did they survive? By Eating/Swallowing Air?
What happened to the GIGANTIC TREES of Those Times?
Funny! Were they capable of Photosynthesis by themselves?

BE...
Geez, man... get a grip....
jsdarkdestruction
5 / 5 (5) Aug 11, 2014
"Dinosaurs were GIANTS. How did they survive? By Eating/Swallowing Air?"

Unless I missed it somehow I don't remember the part where they addressed dinosaurs and the amount of food they needed and was available in the ecosystem they lived in.

"What happened to the GIGANTIC TREES of Those Times?"

they either went extinct or eventually evolved into the trees we now have.
that said, what does that have to do with the article?

"Were they capable of Photosynthesis by themselves?"

I assume that's not a real question and you said it trying to support your unrelated to the article in any way rant.

s_crane2
not rated yet Aug 12, 2014
I guess everybody has seen the video but me. I just spent an hour of my life trying to view it but no luck. Does JWPlayer really work? Too hard, I don't have the time to muck around - I point & click to make stuff happen.
antialias_physorg
5 / 5 (3) Aug 12, 2014
Rangeomorphs have often been considered a 'failed experiment' of evolution as they died out so quickly once the Cambrian Explosion began in earnest

A nearly 100 million years run isn't what I'd call a 'failed experiment'.

I point & click to make stuff happen.

Try point and right-click..or just get an add-in that grabs videos.
Torbjorn_Larsson_OM
5 / 5 (4) Aug 12, 2014
Interestingly, the overall architecture of somewhat spurious body plans survived until today. E.g. cnidarians and bilaterians have very organized (by gene duplications) Hox genes that control development. Rangeomorphs grew locally (fractally), likely all their life, according to the same simple rules. Ctenophores and later porifera however evolved means to constrain early development before Hox genes evolved.

@supramark: Indeed, sponges that spear plancton prey on their limbs look a lot like these while those who filter nutrients are more inverted. The latter evolved a sort of stomach, the invention that did rangeomorphs in. (A stomach means concentrated waste instead of the nutrient bath rangeomorphs could feed from.)
Torbjorn_Larsson_OM
5 / 5 (4) Aug 12, 2014
Don't mind the anti-science creationist trolling, it's only usefulness is that it is hilarious.

However, it is extra hilarious this time. =D The poor fool doesn't know that dinosaurs survived to today, eating like ... birds, which is what they are. Dinosaurs are twice as successful as mammals today at some 10000 vs 6000 species.

There is a serious side to the creationist question, dinosaurs could evolve to their huge size because they didn't evolve mammal constraints. They had bird like hollowed bones so could grow larger faster. And had muscle "stomachs" so they didn't waste time chewing food but it was processed on the way down. Think large elephants, eating all the time, only much faster. But this is all known, give the creos an encyclopedia! =D.
antigoracle
1 / 5 (1) Aug 18, 2014
my first thought on seeing them, "hmm, look a bit like a sponge precursor." Sort of an inside-out sponge.
--supartard
Exactly what a single neuron would conclude.
Graeme
not rated yet Aug 26, 2014
Perhaps these organisms were symbiotic with bacteria that could oxidize ammonia or sulfide or some other inorganic substance. There was probably a bacteria biofilm on the sea floor, and it would try to cover this organism too if it could!

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