A worm with armored teeth may hold the key to unlocking the evolutionary history and diversity of marine invertebrates.
A fossil approximately 520-million years old of the newly discovered worm was found in China. WufengellaThis could be the missing link in the chain between the three phyla which make up the cadre of lophophorates, or sea creatures.
Based on a genetic analysis WufengellaIs probably the common ancestorJakob Vinther (paleontologist) and colleagues report September 27th that brachiopods, bryozoans, and phoronids are connected. Current Biology.
“We had been speculating that [the common ancestor] may have been some wormy animal that had plates on its back,” says Vinther, of the University of Bristol in England. “But we never had the animal.”
Roughly half a billion years ago, nearly all major animal groups burst onto the scene in a flurry of evolutionary diversification during what’s known as Cambrian explosion (SN: 4/24/19). During this time, lophophorates experienced a rapid growth of species, which has obscured the group’s evolutionary history.
The common thread that unites the various phyla is the tentacle-like feeding tubes, known as lophophores. However, the phyla have their own unique characteristics. Brachiopods are shelled creatures that appear to resemble clams at first glance. Bryozoans — commonly known as moss animals — are microscopic sedentary critters that live in corallike colonies. The phoronids (or horseshoeworms) are soft-bodied, unsegmented creatures that live in tubelike, stationary structures. Researchers have recently found that Hyoliths — an extinct animal known by their conical shells (SN: 1/11/17) — are also lophophorates because of the tentacled organ that surrounds their mouth.)
Wufengella doesn’t belong to any of these phyla, Vinther and his colleagues found. The critter is a combination of bristles and armored back plates that are asymmetrical, as well as a wormlike body.
The fossil is a “great find,” says Gonzalo Giribet, an invertebrate zoologist at Harvard University who was not involved in the research. Still, the scientists’ analysis does not confirm that WufengellaHe suggests that it is the long-sought missing piece.
Some researchers had hypothesized that lophophorates’ common ancestor would be a stationary creature that sat on the seafloor and fed only through tubes, similar to its modern kin. Researchers found the following: Wufengella fossil could refute this idea; the animal’s body plan suggests instead that it crawled around, the researchers say.
A fossil like Wufengella had long been high on Vinther’s bucket list of fossils that he and his colleagues hoped to find. But “we always thought, ‘Well, we probably will never see that in real life,’” he says. A creature like this would typically have lived its entire life in shallow waters. Organisms don’t tend to preserve well there, decaying faster due to exposure to lots of oxygen. Vinther suggests that Vinther is right. WufengellaHis team discovered that the storm probably washed out to deep waters.
Researchers have now found one. WufengellaThey hope to discover more varieties, and they also plan to continue to search for them. Vinther believes that perhaps Vinther and his team can identify other distant ancestors, which might link lophophorates to other animal groups, such as mollusks. Vinther adds that this would further flesh out how the Earth’s life is connected.
