500 million-year-old Mystery of Creature with no Anus Solved
Researchers share that they have solved an evolutionary puzzle of a 500 million-year-old microscopic, creature with a mouth yet no anus.
When discovered in 2017, it was reported that the small sack-like aquatic creature’s fossil might be humans’ earliest-known ancestor.
The early creature, Saccorhytus Coronarius, was tentatively placed into a group called the Deuterostomes. A group of animals consisting of vertebrates.
New research now proposes that Saccorhytus better fits into a completely different group of creatures.
Not the Earliest-known Human
A group of scientists in China and the UK performed a detailed X-ray study of the animal and came to the conclusion that it belongs to a group known as the ecdysozoans – ancestors of spiders and insects. One reason for this evolutionary complication was the creature’s lack of an anus.
“It’s a bit confusing – [most] ecdysozoans have an anus, so why didn’t this one?”. Emily Carlisle, a scientist that studied Saccorhytus in detail, explained to BBC Radio 4’s Inside Science.
She added that one “intriguing option”, is that an earlier ancestor of this group did not have an anus, which Saccorhytus developed after that.
“It could be that it lost it during its own evolution – perhaps it didn’t need one because it could just sit in one spot with one opening for everything.”
The major reason for the “repositioning” of Saccorhytus on the Cambrian tree of life is that, on the preliminary evaluation, holes that involved its mouth were taken as pores for gills – a primitive attribute of deuterostomes.
When researchers examined with more detail – using strong X-rays to analyze the 1mm animal closely – they understood that these were the base of spines that had broken off.
Researchers investigating these fossils attempt to position each creature on an evolutionary tree, allowing them to comprehend their origins and how they evolved.
Ms. Carlisle, based at the University of Bristol, explained: “Saccorhytus would have lived in the oceans – in the sediment with its spines holding it in place”.
She added, “It would, we think, have just sat there – in a very strange environment with lots of animals that would have looked like some creatures alive today, but a lot that looked completely alien.”
There Still Much To Be Learned
The rocks holding these Cambrian fossils are still being examined.
“There’s so much we can still learn about its environment,” Ms. Carlisle included.
“The more I study paleontology, the more I realize how much is missing. In terms of this creature and the world it lived in, we’re really just scratching the surface.”
Originally published by: The BBC
