Vanderbilt Graduate Student is Getting to the Bottom of Worm Burrows
By: Sarah Ward, Evolutionary Studies Graduate Communications Assistant
Vanderbilt graduate student Katherine Turk and colleagues found that worm burrowing behaviors could have emerged earlier in earth’s history than was previously thought. Her work Archaeichnium haughtoni: a robust burrow lining from the Ediacaran–Cambrian transition of Namibia was published this January 2024 in Papers in Paleontology, and it could have implications for the onset of complex life on earth.
Turk became interested in better understanding 540-million-year-old (Ediacaran) tubular fossils from the Iziko South African Museum when she realized how indiscriminately the fossils had been characterized in the past.
“They were calling it a wastebasket taxon, which is what you call a fossil when you’re not sure what it is,” said Turk.
She sought to better characterize the fossil slab using her expertise on large, tubular worm fossils from the Ediacaran period.
Paleontologists have a particular interest in the late Ediacaran because it occurred right before a period of exponential growth in the complexity of life on earth. This phenomenon is mostly commonly known as the Cambrian explosion.
“The Ediacaran-Cambrian transition is important, because it’s the beginning of our modern animal dominated biosphere,” said Turk, “it’s the time we start to see animals and animal behaviors with equal complexity to our modern oceans.”
By exploring this transition, paleontologists hope they can determine what may have facilitated a rapid evolutionary boom in the Cambrian.
To better understand the behaviors of Ediacaran animals, paleontologists like Turk look to trace fossils.
“There are two main types of fossils: a trace and a body. A body is a tooth, bone, or shell, while a trace is a record of behavior, like a skin impression, footprint, or burrow,” said Turk, “bodies tell us what an animal looked like, while traces tell us what an animal was doing. Because of this, in a lot of ways, traces can be more valuable.”
Following characterization of trace fossils, paleontologists can connect information on animal behavior to broader evolutionary patterns.
The worm fossils from this particular fossil slab exhibited evidence of important behaviors which would have made it easier for Ediacaran worms to survive and grow.
“Rather than just hanging out where the sediment and water meet and burrowing to the surface, these animals were actually producing reinforced tube structures, which is quite complex,” said Turk.
This behavior, known as worm-burrowing, is an example of ecosystem engineering, where-in worms create tunnels in sediment to protect themselves from predators. Many paleontologists theorize that advancements in ecosystem engineering facilitated the Cambrian explosion, and Turk found that this particular ecosystem engineering behavior emerged far earlier in earth’s history than was previously thought.
In the future, Turk’s work will act as a steppingstone for work on tubular worm fossils, as it will help others more accurately categorize these fossil types from different field sites.
Citation:
Turk, K.A., Pulsipher, M.A., Bergh, E., Laflamme, M. and Darroch, S.A., 2024. Archaeichnium haughtoni: a robust burrow lining from the Ediacaran–Cambrian transition of Namibia. Papers in Palaeontology, 10(1), p.e1546.
Funding Statement:
This work was supported by the Paleontological Society Kenneth E. & Annie Caster Award and the Vanderbilt University Department of Earth and Environmental Sciences Alberstadt–Reesman–Stearns Field Studies Fund, as well as logistical assistance by L. Nelson, W. Taylor and K. Pfennings, and translation support from A. Wehrmann and A. Trozenski. The Iziko South African Museum in Cape Town provided access and authorization to study the fossil material. Federal funding includes NSERC Discovery grant (RGPIN 435402) and NSF-DEB 2051255 grant.