Cambrian Explosion: new complete early form (Introduction)

by David Turell , Saturday, October 01, 2022, 15:36 (784 days ago) @ David Turell

Is the ancestor for three modern groups:

https://www.sciencealert.com/3-major-aquatic-animal-groups-can-trace-their-lineage-to-t...

"A bristly armored "worm" that scuttled across ocean reefs 518 million years ago is the ancestor to three aquatic animal groups that today live very different lifestyles, and it offers new clues about the explosion of diverse species at the time, a new study finds.

"An international team of researchers recently discovered the fossil of a species that gave rise to brachiopods, bryozoans, and phoronids; these three groups of filter-feeding marine creatures all fix themselves to the seafloor, but each group has highly specialized feeding structures and they look very different from one another.

"The fossil species, named Wufengella bengtsoni, is a member of an older, shelled group of organisms called tommotiids, scientists reported in a new study.

***

"Brachiopods are shelled, bivalved creatures; bryozoans are soft-bodied with crowns of tentacles, and phoronids are encased in protective tubes made of chitin, a material that reinforces organic structures such as exoskeletons, beaks, and shells.

***

"The fossil was found at the Chengjiang Biota fossil site in Yunnan, a province in southwestern China. It's a rare find because animals such as this are typically not preserved well enough for paleontologists to study them in detail.

"'They were scuttling around on reefs in the shallow tropical waters that existed back then," Vinther said.

"In these ancient reef systems, dead animals usually were washed around until their bodies disintegrated, and their soft tissues often decayed in the reefs' oxygen-rich waters before fossilization could happen.

"'This particular animal, lucky for us, got washed down into deep water where it got buried in mud where it was preserved," Vinther said.

***

"While the researchers predicted W. bengtsoni's general body plan, some features in the fossil were a big surprise. It had flaps on its body that could have been used for suction purposes, to fix the animal to the reef when there were waves, Vinther speculated.

"The species also had long bristles on its sides that may have been used for sensing prey or as protection against predators.

"The study authors aren't sure what the animal ate, but its body wasn't adapted for filtering water or staying still, so they know it wasn't a filter feeder that attached to the seafloor like its descendants.

"The researchers are confident that it is the ancestor of brachiopods, bryozoans, and phoronids because it shared a similar skeleton with those groups. As life evolved in the Cambrian explosion, animals filled different ecological niches and adopted different body plans.

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"'We're really seeing how these groups fit together, and how they evolved from a single common ancestor. It's taking us up a rung in the evolutionary tree," Smith added."

Comment: this is a great new find, but it just fills niche in a well-established story. dhw keeps hoping for something to remove the Cambrian gap. Not at all likely.