Finding similarities between brachiopodson bryozoans and on phoronids it may seem impossible. All of these sea creatures lead a sedentary lifestyle—attaching themselves to rocks and reefs on the ocean floor. But what characteristics could clam-like, hard-shelled brachiopods share with animals that resemble curly water plants?
Scientists say the answer lies in the origin of these animals. According to recent studies in current biology, all living brachiopods, bryozoans and phoronids can trace their lineage back to a single species, an ancient armored worm known as Wufengela.
“When it first became clear to me what this fossil was that I was looking at under the microscope, I could not believe my eyes. This is a fossil that we have often speculated about and hoped we would one day see,” said study author and paleobiologist Luke Parry at the University of Oxford, according to a press release.
All animals are divided into one of about 30 or more separate categories called species. All of these types have specific sets of anatomical structures that distinguish them from others, and only a few of these structures are included in more than one type.
For example, only three species—brachiopods, bryozoans, and phoronids—share sets of upfolded, grooved tentacles called lophophores. Allowing the animal to catch particles of food as they drift through the sea, these specialized tentacles provide the three species with their collective name, ‘lophophorates’. They also offer an anatomical clue that lophophorates may be closely related, despite other differences in their body structures.
Now, a particularly well-preserved fossil specimen from 518 million years ago provides further support for the close ancestry of these three species. It reveals that their most recent common ancestor was probably Wufengela, an agile, armored kind of worm.
“This discovery highlights how important fossils can be for reconstructing evolution,” said Greg Edgecombe, study author and researcher at the Natural History Museum in London, according to a press release. “We get an incomplete picture by looking only at living animals, with the relatively few anatomical features that are shared between species. With fossils like Wufengelawe can trace each lineage back to its roots, realizing how they once looked completely different and had very different ways of life, sometimes unique and sometimes shared with more distant relatives.”
According to the team of researchers analyzing the gap, Wufengela it was a small, short sort, less than an inch long. The ancient worm was protected by a series of armored, shell-like plates and covered with numerous lobe-like projections and tufts of bristles on either side of its body.
These traits, the researchers say, in addition to the internal structures in the worm’s body, suggest a shared origin of the species with the lophophorates. Plus, when combined with molecular analyzes of the animals’ amino acid sequences, they confirm that today’s brachiopods, bryozoans and phoronids are closely related.
“Wufengela belongs to a group of Cambrian fossils that are critical to understanding how lophophorates evolved,” Parry says.