An international team of paleontologists and evolutionary biologists have described a previously unknown "sea monster". His remains were found in the south of modern China.
The creature, dubbed Daihua sanqiong, lived on the planet 518 million years ago. Its main distinguishing feature was 18 tentacles located around the mouth.
When experts compared the remains of the "monster" with similar fossils, they had little doubt that the species D. sanqiong were relatives of ctenophores. Since recently, these marine life have been considered the "progenitors" of all animals, so it is not surprising that evolutionary biologists are interested in the new find.
The authors of the study clarify that they found a fossil in a rock called mudstone. She looked like a fancy flower. (Actually, this feature is reflected in the name of the genus Daihua: the first part of the word (dai) is a reference to a group of Asian peoples called the Dai, and the second (hua), translated from the Mandarin Chinese dialect, means “flower”.)
On the "petals", which actually turned out to be tentacles, the experts found thin feather-like processes with rows of large hair-like cilia. Similar sticky cilia are found in modern comb jellies: they need them to swim and capture prey.
It is noteworthy that the "sea monster" was surprisingly similar to the other two ancient creatures. First, an individual of the new species resembles a fossil animal of the genus Dinomischus. His remains, 508 million years old, have been found in the Canadian Burgess Shale. This creature also had 18 tentacles and an organic skeleton. Previously, it was referred to as invertebrates under the name intra-powder.
The team believes that both of these animal genera (Dinomischus and Xianguangia) shared common ancestors with D. sanqiong. What's more, these creatures also have ancient kinships with coral polyps, sea anemones, and jellyfish.
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Apparently, the ancestors of ctenophores were polypid creatures that could not swim and lead a sedentary lifestyle, that is, they clung to the seabed (like modern polyps). Their sticky tentacles then developed into thinner and more mobile ciliary "ridges", thanks to which the ctenophores acquired the ability to move in the water column.
Over time, their mouths widened and their bodies shrank, causing the tentacles that previously surrounded the mouth opening to move to the back of the body (like the tentacles of jellyfish).
At the same time, some early Cambrian forms of ctenophores (already able to swim), apparently, still possessed an organic skeleton.
Scientists admit that all these transformations complicate the study of ctenophores: they have undergone many genetic changes and acquired morphological features similar to those of many other animals.
In the future, experts want to learn more about the ancient connections of ctenophores with corals, sea anemones and jellyfish, as well as rethink the pedigree of all these creatures.
A scientific article with a more detailed description of the "sea monster" was published in the journal Current Biology.
