A team of paleontologists has discovered the oldest animal with a skeleton. Called Coronacollina acula, the organism is between 560 million and 550 million years old, which places it in the Ediacaran period, before the explosion of life and diversification of organisms took place on Earth in the Cambrian.
The finding provides insight into the evolution of life particularly, early life on the planet, why animals go extinct, and how organisms respond to environmental changes. The discovery also can help scientists recognize life elsewhere in the universe.
The Ediacaran Period, named after the Ediacara Hills of South Australia, ranges 630-542 million years ago. The Cambrian Period, marked by a rapid diversification of life-forms on Earth as well as the rise of mineralized organisms, ranges 542-488 million years ago.
"Up until the Cambrian, it was understood that animals were soft bodied and had no hard parts," said Mary Droser, a professor of geology at the University of California, Riverside, whose research team made the discovery in South Australia. "But we now have an organism with individual skeletal body parts that appears before the Cambrian. It is therefore the oldest animal with hard parts, and it has a number of them - they would have been structural supports - essentially holding it up. This is a major innovation for animals."
Coronacollina acula is seen in the fossils as a depression measuring a few millimeters to 2 centimeters deep. But because rocks compact over time, the organism could have been bigger 3 to 5 centimeters tall. Notably, it is constructed in the same way that Cambrian sponges were constructed.
"It therefore provides a link between the two time intervals," Droser said. "We're calling it the 'harbinger of Cambrian constructional morphology,' which is to say it's a precursor of organisms seen in the Cambrian. This is tremendously exciting because it is the first appearance of one of the major novelties of animal evolution."
According to Droser, the appearance of Coronacollina acula signals that the initiation of skeletons was not as sudden in the Cambrian as was thought, and that Ediacaran animals like it are part of the evolutionary lineage of animals as we know them.
Study results appeared online Feb. 14 in Geology.
The researchers note that Coronacollina acula lived on the seafloor. Shaped like a thimble to which at least four 20-40-centimeter-long needle-like "spicules" were attached, Coronacollina acula most likely held itself up by the spicules. The researchers believe it ingested food in the same manner a sponge does, and that it was incapable of locomotion. How it reproduced remains a mystery.
Coronacollina acula is so named because it translates as "little rimmed hill with needles" (corona rim or crown; collis hill; acula needle). The name describes the fossil organism's morphology, and, specifically, its two components: the truncated cone-shaped body, which appears in the fossils as a pit, and the long brittle spicules, which appear in the fossils as thin grooves.
Ediacaran fossils often show the imprint of the whole body of the organism. With Coronacollina acula, however, skeletal parts were found to have fallen off.
"If you have soft parts holding your body together, then, as they decay, you lose your skeletal parts," Droser explained. "Which is why it's rare to find two clam shells together in fossils. We've now found whole organisms of Coronacollina acula the thimble-shaped body in the center, with spicules coming off it like knitting needles. And we have found hundreds of them. They appear to have been a gregarious species, with a lot of them living together."
Droser explained that the spicules had to have been mineralized because the casts show they are ruler-straight. Moreover, they broke.
"We often associate skeletons with predation since skeletons greatly assist animals in their fight against predators," Droser said. "But Coronacollina acula used its skeleton only for support, there being no predators in the Ediacaran."
The research work began as a master's thesis project in Droser's lab. Erica Clites, now a physical science technician at Glen Canyon National Recreation Area for the National Park Service, chose to work on this project because it promised a good challenge with rewarding results.
"Every aspect of the organism's reconstruction had to be backed up by supporting statistics," said Clites, who graduated from UCR in 2009 and is the first author of the research paper. "Through painstaking measurements and detailed descriptions, the pits and needles contained in the rock were revealed as a sponge-like animal."
Droser and Clites were joined in the study by James G. Gehling of the South Australian Museum, Adelaide.
Explore further:
Fossils show earliest animal trails
Urgelt
A different reasonable guess might be that the spicules anchored them against currents. Or tides, if they could have been tidal creatures.
I assume there were predators preying on these creatures. Perhaps it's just as logical to guess that the spicules, radiating out from colonies of Coronacollina, might have discouraged predation?
How did they reproduce? Asexually, perhaps. I have it stuck in my head that the Cambrian explosion of life-forms may have been triggered by the development of gender and sex, which sped up genetic diversification and adaptation. (Caveat: just because an idea sticks in my head, alas, is not proof it is true.)
Callippo
Mar 08, 2012John_Randall
CardacianNeverid
The article states that there were no predators at that early age (Ediacaran).
jsdarkdestruction
TheWalrus
Who'd have thought a respected popular science Web site would have comments of the same quality as YouTube? With all the crackpots out there, it's amazing science ever got off the ground.
CardacianNeverid
Fortunately the crackpots of today can never get past the front door of a reputable scientific organization, which is why they infect internet sites where the intellectual price of admission is not required.
Ethelred
There are two or more with Smrit Sorli who cranked on other articles than those covering him. So crackpots can still get past the door. They become crackpots AFTER they get past the door.
Zephir's other sockpuppet, Rawa1, seems to have been banned. How come they only banned the one and not Callipo as well. Even the mods have to know its the same person.
He was doing so well on that post and then he couldn't help himself. He HAD to crank out crap about AWITSBS.
Ethelred
Ethelred
O2 concentrations may have increased. There may have been an end to a major ice age of global proportions. Eyes and calcification started at the same time.
A big possibility that no one has ever mentioned, at least that I have seen, is the development of a circulatory system with O2 transport but even the Burgess Shale fossils aren't good enough to show that.
I think it was a confluence of things but sex sure could have been the initiating reason that the more complex organism that evolved those things were able to evolve them.
Word wuze of the worst sort. Nothing of that had anything to do with sex. Or bosons, fermions or the hypothetical graviton or even cooling.
Ethelred
Sinister1811
bewertow
reported for spamming. I encourage everyone else who finds this crap annoying to do so as well.
roboferret
there's Kinedryl too - http://www.physor...inedryl/
Same MO:
http://www.physor...son.html
It's not even good sockpuppetry. No attempt is made to make them look like different people, and he often carries on the same conversation with different accounts. Really bizarre behaviour.
Peteri
@Callippo
Judging from your crass and ill-informed comments on Physorg and the utter pseudo-scientific garbage you spout on your AWT web site, you were obviously one of those lazy-minded students who nodded off in your science lessons!
Go play "let's pretend to be a scientist" somewhere else and stop clogging up serious discussion threads with your nonsense.
Callippo
Callippo
Callippo
Ethelred
Lying about it won't make reality go away.
AWITSBS is based on two stupid theories that don't fit reality and one of the laughable theories you have to changed to require 'variations in infinite density' which is self-contradictory. Plus gravitons are hypothetical low energy MASSLESS particles so they cannot decay into massive particles.
Lie. I said ONE part was possibly right. After all, you agreed with me on the sexual issue which I have posted before. The rest was ludicrous nonsense as I pointed out already.
Another lie. YOUR blindness does not constitute our blindness. Nothing was wild except the rubbish you followed up the sexual reproduction concept with.>>
Ethelred
That word does not mean what you think it means.
Logic does not constitute theories that are self contradictory.
No. And isn't rote learning as you usually lie about either.
You didn't claim that. Nor is it reasonable since the snow ball Earth period, if it really existed, lasted for a very long time. Now if you were to claim that it was the END of the snowball era then you might have a point BUT that is clearly not all that was going on.
I will go through the what seem to be the key points of what MAY have involved.
Life started, how is unknown and probably unknowable.>>
Ethelred
The freed O2 was captured by the dissolved iron to form the insoluble iron oxides which are found in the banded iron formations. It took a LONG time for almost all the iron to be oxidised. The process of taking CO2 from the atmosphere lowered the amount of greenhouse gases in the atmosphere thus lowering the Earth's temperature which is what would have been the cause of the snowball Earth should it be confirmed. At the end of this period there was enough free O2 to support more active lifeforms AND it may have promoted the evolution of the nucleus as zone in the cells with little free O2.>>
Ethelred
That lays the basic biochemical evolution of sexually reproducing eukaryotes to the time period of the oxygenated snowball Earth. Not to gravitons nor directly to the cold but to the free O2 which was the result of the CO2 binding that led to the snowball Earth.
The basics of the biochemistry of sexual reproduction must have taken a long time to sort out. Sexual organs and specialization into two sexes couldn't occur till there were multicelled organisms with specialized cells.>
Ethelred
That causes it to look like it happened all at once. That is combined with an apparent tendency for paleontologists to forget just how long twenty million years really is when life is CREATING new niches for the new life forms to adapt too.
So quit lying that I am going on rote memorization. That is mostly my own thinking and it all fits the known evidence without any silly claims dependent on variations in infinite density.
Ethelred
Peteri
One of the problems is that your grammar is so bad it's sometimes hard to understand exactly what you are trying to say! Of course, if English is not your first language, you have a reasonable excuse.
Your argument(s) that everyone should disprove your hogwash is nicely countered by the philosopher Bertrand Russell - basically the burden of proof lies upon the person (i.e. you) making scientifically unfalsifiable claims rather than shifting the burden of proof to others. Russell summed it up quite nicely in his celestial teapot analogy - basically, if he claimed that a teapot was orbiting the Sun between Earth and Mars, it would be nonsensical for him to expect others not to doubt him on the grounds that they could not prove him wrong.
So, sorry, it is YOU who have to to provide the burden of proof in the face of overwhelming evidence to the contrary!
Ethelred
Since you have nothing to say to support those ones you gave me I am going to return the favor.
Ethelred
Ethelred
Yes he is a racist and a complete nutcase. Here is a link:
http://www.physor...vey.html
That is not the only discussion where he gave away his irrational thinking.
Ethelred