I've emerged from the darkness to post ediacara! back to the abyss i go
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I've emerged from the darkness to post ediacara! back to the abyss i go
Charniplex, the Fractal Pokémon!
Type: Dark/Ground
Instead of growing by branching off new segments or growing bilaterally, Charniplexes would actually expand fractally; starting from the base, it would grow a lobe off one side of its central axis, then the other side, then the other. This process is called glide reflection, and it creates Charniplex’s distinctive asymmetric pattern.
Cambrian Explosion Month #04: Phylum Ctenophora (And Petalonamae?)
Much like the sponges, the ctenophores (commonly known as "comb jellies"), are one of the oldest animal lineages, but their exact position in the evolutionary family tree is a little uncertain. Traditionally they're placed between sponges and all other animals, as the earliest branch of the eumetazoans, but some studies have suggested that they might be much more ancient, possibly branching off before even the sponges did.
And while their fossil record is poor due to their soft gelatinous bodies, some of what we do have is starting to hint that their ancestry was very different from their modern jellyfish-like representatives – and they might even have links to some weird Precambrian creatures.
At first glance Stromatoveris psygmoglena from the Chinese Chengjiang fossil deposits (~518 million years ago) doesn't even look like a ctenophore, instead more closely resembling a sea pen or one of the frond-like Ediacaran organisms. Up to 10.5cm tall (~4"), it was a sessile animal that lived attached by a holdfast to the sea floor, with up to four branched "petaloid" fronds that would have been used to catch food particles in the surrounding water.
It's been interpreted as a comb jelly relative based on the possible presence of cilia on its fronds, suggesting that the group may have originated as sedentary suspension feeders and later evolved a free-swimming mode of life. Along with the discovery of other fossils that might be sessile ctenophores, and a lineage of swimming forms with spiny skeletons, it's definitely seeming that the early evolution of this group was much stranger than expected.
However, Stromatoveris also might not be a comb jelly at all, and instead might really be a Cambrian representative of the fronded Ediacaran animals it so closely resembled. More recent studies of additional fossils suggest that it was part of a group of early animals called petalonamids, closely related to the weird fractal-branching rangeomorphs.
…But, of course, there's always the possibility that both relationships are correct, and that the Ediacaran frond animals were actually early ctenophores – an idea originally proposed back in the early 2000s, before Stromatoveris had even been discovered.
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Other Cambrian ctenophores were much more recognizable, but also had much larger numbers of comb rows on their bodies.
Fasciculus vesanus had one of the oddest arrangements, with two sets of long and short rows totalling 64 compared to modern ctenophores' 8. Known from the Canadian Burgess Shale deposits (~508 million years ago), it measured about 11cm in diameter (4.3") and was either a very rare member of the ecosystem or just very rarely fossilized, with only a single specimen ever found.
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Some future patch designs, hopefully.
mighty morphin’ power rangeomorph
Pectinifrons
Species: P. abyssalis
Etymology: “Comb of leafy branches,” after its shape
Age and Location: Ediacaran of Newfoundland
Classification: ?Eukarya: incertae sedis: Rangeomorpha
Pectinifrons is a rangeomorph, and so broadly similar to Fractofusus, which also was a sessile organism that reclined on the surface, and with which it shared a presumed osmotrophic lifestyle and fractal anatomy. However, despite the simplicity of their body plans, there was still substantial variation between different genera. Pectinifrons was an enormous organism by Ediacaran standards, with the largest individuals being nearly a meter long. Unlike Fractofusus, which lay flat on the seafloor, Pectininfrons was taco-shaped, with its midline lying on the seafloor and two rows of fronds sticking upward. While superficially it resembled a folded Fractofusus, though, it appears to have grown differently: all Fractofusus have the same number of fronds and are essentially identical except for size, while larger Pectinifrons have more fronds. This suggests that Fractofusus developed an adult morphology early in life and simply grew by expanding itself, whereas Pectinifrons grew by lengthening the midline of its body and growing additional fronds. Such a dramatic difference in growth strategies suggests that the rangeomorphs might be more diverse than previously thought. What kind of organism rangeomorphs are--or if they’re a single kind of organism at all--remains unknown.
Sources
Bamforth EL., Narbonne GM., Anderson MM., Bamforth EL., Narbonne GUYM., Anderson MM., Crescent S. 2008. Growth and Ecology of a Multi-Branched Ediacaran Rangeomorph from the Mistaken Point. Journal of Paleontology 82:763–777. Hoyal Cuthill JF., Conway Morris S. 2014. Fractal branching organizations of Ediacaran rangeomorph fronds reveal a lost Proterozoic body plan. Proceedings of the National Academy of Sciences of the United States of America.
RANGEOMORPH ("Form like Rangea" – rangea being a frond-like Precambrian organism) Ediacaran (Late Precambrian) — from Flinders, Australia
Rangeomorph communities are similar in structure to those of contemporary suspension-feeding animals, but it is difficult to relate their morphology to any modern animals. They probably represent an extinct stem group to either the animals or fungi. [ X ] [See also charnia.]
ILLUSTRATION Pambikalbae hasenohrae by =avancna
The fractal construction may represent a convergent adaptation to osmotic feeding. However, most researchers now consider it to be an apomorphy [an innovative form that might be used to define a clade] – one that establishes the rangeomorph clade as a valid taxonomic entity [ X ]
Sea Pens (marine cnidarians belonging to the order Pennatulacea) are an example of a modern animal that is, misleadingly, similar in form to Pambikalbae. ⇓