An historical, armored worm would be 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, may be the lacking hyperlink between three of the phyla that represent a cadre of sea creatures referred to as lophophorates.
Based mostly on a genetic evaluation, Wufengella might be the widespread 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 often known as the Cambrian explosion (SN: 4/24/19). Throughout this time, lophophorates skilled a fast progress of species, which has obscured the group’s evolutionary historical past.
One factor that ties collectively the completely different phyla of the group is their tentacle-like feeding tubes often known as lophophores. However past that commonality, the phyla are all fairly completely different. Brachiopods are shelled animals that at the beginning look resemble clams. Bryozoans — generally often known 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 buildings. (Extra not too long ago, some researchers have decided that hyoliths — an extinct animal recognized 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 much like these of brachiopods, horseshoe worms or bryozoans: a sequence of uneven, armored again plates, a wormlike physique and bristles that stand out from 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 affirm that Wufengella is the long-sought lacking hyperlink, he cautions, however fairly suggests it.
Some researchers had hypothesized that lophophorates’ widespread ancestor could be a stationary creature that sat on the seafloor and fed solely by way of tubes, much like its trendy kin. The Wufengella fossil may refute this concept; the animal’s physique plan suggests as an alternative that it crawled round, the researchers say.
A fossil like Wufengella had lengthy been excessive on Vinther’s bucket record of fossils that he and his colleagues hoped to search 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 likely to protect effectively there, decaying sooner on account of publicity to a number of oxygen. Vinther means that the Wufengella that his crew discovered most likely washed out to deep water in a storm.
Now that the researchers have discovered one Wufengella, they hope to search out extra, partially to see if there are different varieties. And maybe the crew may establish much more distant ancestors additional again on the tree of life that may join lophophorates with different animal teams resembling mollusks, Vinther says, additional fleshing out how life on Earth is linked.