Pan and SFU Earth Sciences professor Shahin Dashtgard are part of an international team that named the homes of these ancient giant worms Pennichnus formosae. Pan initiated the work while completing her M.Sc. degree under the supervision of Professor Ludvig Löwemark, from the Department of Geosciences at National Taiwan University, Taiwan.
After investigating 319 specimens preserved in early Miocene strata (22 million – 20 million years ago) in northeast Taiwan, the morphological model of this trace fossil was constructed.
Shahin encouraged us to reach out to marine biologists, marine photographers and aquarium keepers to compare the burrows to biological analogs, which enabled us to reach the conclusion that this trace fossil was produced by giant, ambush-predatory worms, says Pan.
The modern-day Bobbit worm, which is also large and predatory, is sometimes called the sand striker, sensing prey with its antennae, then grabbing them with its powerful jaws, and retreating into its burrow. When it burrows, its body occupies the whole burrow which explains the two-metre-long burrow observed in Pennichnus.
Further analysis revealed a high concentration of iron around the upper burrow, leading researchers to believe the worm secreted mucus to reinforce and rebuild its burrow wall after each feeding.
Modern Bobbit worm burrow openings are similar to that of Pennichnus, suggesting that the sediment collapsed into the burrow upon retreating or pulling still live prey below the seafloor.
Marine predatory worms have existed since the early Palaeozoic (> 400 million years ago), but their soft tissue bodies decay leaving little trace of their existence behind. Pennichnus formosae is believed to be the first known trace fossil produced by a sub-surface ambush predator, allowing researchers a rare opportunity to learn more about this ancient sand strikers behaviour.
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Giant sand worm discovery proves truth is stranger than fiction – SFU News – Simon Fraser University News
