An animal that may very well be mistaken for a spiky fruit is giving scientists a peek into what mollusks seemed like round 500 million years in the past.
Fossils of an historical invertebrate dubbed Shishania aculeata present that the animal was a sluglike creature coated in prickly armor, researchers report within the Aug. 2 Science. The discover bolsters proof suggesting that early mollusks lacked shells and have been coated in spikes made from chitin, a fibrous materials present in present-day crab and different mollusk shells (SN: 10/13/22).
At present’s mollusks are an extremely various group of animals, says paleobiologist Xiaoya Ma of Yunnan College in China. With residing species as totally different as clams and octopuses, it’s powerful to search out widespread traits that point out what the group’s earliest ancestors seemed like. However “fossils can usually present distinctive and direct proof” for the way early mollusks appeared, Ma says.
The fossils, which have been uncovered in China, date to round 510 million years in the past following an early Cambrian interval when there was a speedy burst of evolution for mollusk ancestors (SN: 6/11/94). Ma and colleagues examined a complete of 18 specimens, ranging in measurement roughly from 1 to six centimeters lengthy. Every specimen was “not all the time stunning,” Ma says. Tender tissues like these in S. aculeata’s physique don’t fossilize nicely. “However they preserved or compressed from totally different angles … [which] helps us put a jigsaw [puzzle] collectively to reconstruct the animal.”
S. aculeata’s base is flat, with a singular foot. This mollusk attribute helps the animals scooch throughout the bottom or dig into gentle sediments. What’s extra, the hole chitin cones that make the organism resemble a durian fruit on the surface are full of slender canals which might be “spectacular and very uncommon,” Ma says. These canals are much like these discovered within the exoskeletons of extinct and residing worms and brachiopods, suggesting a typical origin.
