Spot the similarities between the brachiopodsthe bryozoans and the the phoronids may seem impossible. These sea creatures all live sedentary lifestyles – attaching themselves to rocks and reefs along the ocean floor. But what characteristics might clam-like, hard-shelled brachiopods share with animals that look like frilly aquatic plants?
Scientists say the answer lies in the ancestry of these animals. According recent search in current biology, all living brachiopods, bryozoans and phoronids can trace their lineage to a single species – an ancient armored worm known as Wufengella.
“When I first realized what this fossil was that I was looking at under a microscope, I couldn’t believe my eyes. It’s a fossil we’ve often speculated about and hoped to one day lay eyes.” said Luke Parry, study author and paleobiologist at the University of Oxford, according to a press release.
All animals are separated into one of approximately 30 distinct categories called phyla. These phyla all exhibit specific sets of anatomical structures that distinguish them from others, and only a few of these structures are included in more than one phyla.
For example, only three phyla—brachiopods, bryozoans, and phoronids—share sets of folded, frilled tentacles called lophophores. Allowing an animal to grasp food particles as they float in the sea, these specialized tentacles give the three phyla their collective title, “lophophorates”. They also offer an anatomical clue that the lophophorates might be closely related to each other, despite the 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 phyla. It reveals that their most recent common ancestor was probably the Wufengella, a species of agile and armored worm.
“This discovery highlights the importance of fossils for reconstructing evolution,” says 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 characters that are shared between different phyla. With fossils like Wufengellawe can trace each line 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 fossil, Wufengella was a small, short species less than an inch long. The ancient worm was protected by a set of shell-like armored plates and covered with a number of lobe-like protrusions and tufts of hair on all sides of its body.
These traits, the researchers say, in addition to the worm’s internal body structures, imply the species’ shared ancestry with the lophophorates. Moreover, when combined with molecular analyzes of animal amino acid sequences, they confirm that today’s brachiopods, bryozoans, and phoronids are all closely related to each other.
“Wufengella belongs to a group of Cambrian fossils that is crucial to understanding how lophophorates evolved,” says Parry.