Evolution: pre-Cambrian rangeomorphs (Introduction)

by David Turell , Tuesday, July 25, 2017, 22:33 (2679 days ago) @ David Turell

Another study of their internal parts using special techniques. Still not known if animal or vegetable:

https://www.newscientist.com/article/2141777-see-inside-the-580-million-year-old-creatu...

"Now, CT scans of a pair of unusual three-dimensional fossils found in Namibia are telling us more about the mysterious organisms. The two fossils are from a single 10-centimetre-tall Ediacaran species called Rangea. It is a member of an Ediacaran group called the rangeomorphs that looked a bit like large petals.

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"From an initial examination of the same fossil in 2013, Sharp’s colleagues concluded that its six fern-like fronds looked like flat fins protruding out at equal distances from a central axis, like a starfruit with six segments.

"The new analysis updates that description. The scans shows that one of the three fronds had a three-dimensional shape, more like an inflated balloon than a flat fin. The other two fronds are flatter, but probably only because they were squashed during fossilisation.

"Sharp and her colleagues think all six fronds may have been inflated like long balloons. They may even have touched one another – meaning that a horizontal section through Rangea would have looked more like a slice through an orange rather than one through a starfruit.
“Our work supports a lifestyle of absorption of nutrients through membranes inflated to the maximum, increasing the surface area across which these organisms seemed to feed,” says Sharp.

"The CT scans also confirm that Rangea had a cone-shaped channel running up its central trunk. The lower part of this channel seems to be filled with sediment of a different composition from the sediment filling the rest of the fossil. Sharp says it was probably present in Rangea even when the organism was alive, helping to support the creature like a primitive skeleton.

“'These beautiful, three-dimensional Ediacaran fossils are comparatively rare,” says Jennifer Hoyal Cuthill at the University of Cambridge. “There’s still so much to discover about what these creatures were and how they lived, and detailed information on their anatomy is very valuable.”

"However, even with these new insights, it is still unclear what the Ediacarans were. “They may or may not be animals – we can’t say from this study,” says Sharp. “But they are the first of the truly large, multicellular organisms that radiated broadly before the first true animals evolved.'”

Comment: These very simple organisms lived At the bottom of seas just prior to the appearance of the earliest complex Cambrian organisms. A huge gap in form and function still exists at this point in the past. Darwin hoped it would be explained as it was exactly opposite to his theory of a gradualism type of evolution. Gradualism at any point in evolution has never been found.