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An historic, armored worm often is the key to unraveling the evolutionary historical past of a various assortment of marine invertebrates.
Found in China, a roughly 520-million-year-old fossil of the newly recognized worm, dubbed Wufengella, is likely to be the lacking hyperlink between three of the phyla that represent a cadre of sea creatures known as lophophorates.
Based mostly on a genetic evaluation, Wufengella is probably the common ancestor that connects brachiopods, bryozoans and phoronid worms, paleontologist Jakob Vinther and colleagues report September 27 in Present Biology.
“We had been speculating that [the common ancestor] could have been some wormy animal that had plates on its again,” says Vinther, of the College of Bristol in England. “However we by no means had the animal.”
Roughly half a billion years in the past, practically all main animal teams burst onto the scene in a flurry of evolutionary diversification throughout what’s referred to as the Cambrian explosion (SN: 4/24/19). Throughout this time, lophophorates skilled a speedy development of species, which has obscured the group’s evolutionary historical past.
One factor that ties collectively the totally different phyla of the group is their tentacle-like feeding tubes referred to as lophophores. However past that commonality, the phyla are all fairly totally different. Brachiopods are shelled animals that initially look resemble clams. Bryozoans — generally referred to as moss animals — are microscopic sedentary critters that stay in corallike colonies. And phoronids, or horseshoe worms, are unsegmented, soft-bodied creatures that stay in stationary, tubelike constructions. (Extra lately, some researchers have decided that hyoliths — an extinct animal identified by their conical shells (SN: 1/11/17) — are additionally lophophorates due to the tentacled organ that surrounds their mouth.)
Wufengella doesn’t belong to any of those phyla, Vinther and his colleagues discovered. However the critter has traits just like these of brachiopods, horseshoe worms or bryozoans: a collection of uneven, armored again plates, a wormlike physique and bristles that stand proud of lobes surrounding its physique.
The fossil is a “nice discover,” says Gonzalo Giribet, an invertebrate zoologist at Harvard College who was not concerned within the analysis. Nonetheless, the scientists’ evaluation doesn’t verify that Wufengella is the long-sought lacking hyperlink, he cautions, however relatively suggests it.
Some researchers had hypothesized that lophophorates’ widespread ancestor can be a stationary creature that sat on the seafloor and fed solely by means of tubes, just like its fashionable kin. The Wufengella fossil might refute this concept; the animal’s physique plan suggests as a substitute that it crawled round, the researchers say.
A fossil like Wufengella had lengthy been excessive on Vinther’s bucket listing of fossils that he and his colleagues hoped to seek out. However “we all the time thought, ‘Nicely, we most likely won’t ever see that in actual life,’” he says. Sometimes, such a creature would have spent its life in shallow water. Organisms don’t are inclined to protect properly there, decaying sooner as a result of publicity to a lot of oxygen. Vinther means that the Wufengella that his workforce discovered most likely washed out to deep water in a storm.
Now that the researchers have discovered one Wufengella, they hope to seek out extra, partly to see if there are different varieties. And maybe the workforce might determine much more distant ancestors additional again on the tree of life that may join lophophorates with different animal teams similar to mollusks, Vinther says, additional fleshing out how life on Earth is related.
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