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Researchers at Simon Fraser University have found evidence that large predatory ambush worms – some measuring up to two meters – roamed the ocean floor near Taiwan more than 20 million years ago. The report, published today in the journal Scientific reports, is the result of the reconstruction of an unusual fossil trace that they identified as a burrow of these ancient worms.
According to the study’s lead author, SFU Earth Science PhD student Yu-Yen Pan, the fossil trace was found in a rocky area near the coast of Taiwan. Traces of fossils are part of an area of research called ichnology. “I was fascinated by this monster burrow at first glance,” she says. “Compared to other traces of fossils which are usually only a few tens of centimeters long, this one was enormous; two meters long and two to three centimeters in diameter. The distinctive feather-like structures around the upper burrow were also unique, and no previously investigated fossil record showed similar characteristics. “
Pan and Shahin Dashtgard, professor of earth sciences at SFU, are part of an international team that has named the homes of these ancient giant worms Magnificent Pennichnus!. Pan initiated the work while completing his M.Sc. degree under the guidance of Professor Ludvig Löwemark, Department of Geosciences, National Taiwan University, Taiwan.
After studying 319 specimens preserved in strata from the early Miocene (22 million to 20 million years ago) in northeastern Taiwan, the morphological model of this fossil trace was constructed.
“Shahin encouraged us to contact marine biologists, marine photographers and aquarium keepers to compare the burrows to biological analogues, which led us to conclude that this fossil trace was produced by predatory giant worms of ‘ambushes,’ says Pan.
The modern-day Bobbit worm, which is also large and predatory, is sometimes referred to as the “ sand attacker, ” detecting prey with its antennae, then grabbing them with its powerful jaws and retreating into its burrow. When it digs, its body occupies the entire burrow which explains the two-meter-long burrow observed in Pennichnus.
Further analysis revealed a high concentration of iron around the upper burrow, leading researchers to believe that the worm secreted mucus to strengthen and rebuild its burrow wall after each feeding.
Modern Bobbit worm burrow openings are similar to those of Pennichnus, suggesting that sediment has collapsed into the burrow during the withdrawal or pulling of still living prey below the seabed.
Predatory marine worms have been around since the early Paleozoic (> 400 million years ago), but their soft tissue decays leaving little evidence of their existence. Pennichnus formosae is believed to be the first known fossil record produced by a predator lurking beneath the surface, providing researchers with a rare opportunity to learn more about the behavior of this ancient sand attacker.
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Material provided by Simon Fraser University. Note: Content can be changed for style and length.
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