Before animals came to rule the world, there was a bizarre organism swaying in the oceans. Looking somewhat like a modern-day fern, the organism had long fronds with branching veins. Known as Ediacarans, they are believed to have been the first truly large multicellular organisms, and yet we still know very little about them.
Now, researchers have put a pair of 580-million-year-old fossil Ediacarans – belonging specifically to a group called rangeomorphs – through a CT scanner to see if they can determine anything new about these weird soft-bodied creatures. Published in the journal Precambrian Research, they found that these organisms lived in three-dimensions and had a central channel running up their middle that may have been filled with a sediment that acted like a primitive skeleton.
The researchers, however, are still uncertain whether rangeomorphs were actually plants or animals. You might think this is a fairly straightforward distinction to make, but there are plenty of animals alive today that could fool most. The fact that these creatures were soft-bodied makes it even trickier to be certain, as all that's usually preserved are the imprints and surface structures.
This is why the fossil finds used in the study, uncovered in the deserts of Namibia, are so rare and vital – they show a preserved Edicarian in three-dimensions. The researchers hoped that by putting it through a CT scanner, they might be able to build not only an unprecedented idea as to what the organism looked like in real life, but potentially how it behaved too.
Previous fossil evidence suggested that the rangeomorphs’ flat leaf-like structures may have been arranged somewhat akin to a starfruit, radiating out from a central stalk. But this pair of fossils, thought to be from the same individual, show that these “leaves” may actually have been inflated during the organism's life.
“This is the first look inside such a unique specimen of a rangeomorph,” explained team lead Alana Sharp, from University College London, to New Scientist. “What has been made visible are internal structures like a central core.”
They were also able to see how the organism puffed itself up, sort of like a balloon. The researchers think that this might have been related to how the creatures fed, and that by increasing the surface area of their fronds, the organisms would be able to absorb more nutrients from the water column.
Unfortunately, the CT scans were still unable to fundamentally answer whether or not these rangeomorphs were plants or animals.
[H/T: New Scientist]