Researchers have made a significant discovery regarding the Olenoides serratus, a trilobite that thrived in the Burgess Shale of British Columbia over half a billion years ago. This fantastic beast had highly specialized appendages such as paddles for swimming, clublike limbs for digging, and pincers for scavenging undersea invertebrates that made up its diet. Those results take researchers a step closer to understanding how this ancient creature lived and moved. They provide an unparalleled glimpse into what life was like during the Cambrian explosion period.
Until recently, Olenoides serratus was best known for its incredibly well-preserved fossils showcasing arthropod specific, hundreds-of-millions-year-old limb waving. These fasciated adaptations gave the trilobite access to a whole world of behaviors. As we noted, it was able to produce trace fossils at various depths and masterfully maneuver around barriers in its environment. The Burgess Shale was quickly buried by debris flow deposits, similar to an underwater landslide. This low-oxygen environment acted to preserve the delicate details of these fossils unprecedentedly well.
Insights from the Fossils
The find of Olenoides serratus is especially notable for giving us some of the rarest insights into the behavior of ancient organisms. Fossilized remains of this giant trilobite exhibit its remarkable prowess to raise its entire body above the seafloor. This adaptation helped it to jump over barriers and travel effectively through rapidly moving currents.
“They could raise their body above the sediment in order to walk over obstacles or to move more efficiently in fast-flowing water,” – Sarah R. Losso.
Scientists are used to discovering fossilized limbs preserved at all sorts of wacky angles. This diversity empowers them to produce more intricate 3D digital replicas for improved study. By learning from these models, researchers can get a better sense of how Olenoides serratus moved through and interacted with its environment.
“Understanding behavior and movement of fossils is challenging, because you cannot observe this activity like in living animals,” said Losso, emphasizing the difficulties faced by paleontologists when interpreting fossilized evidence.
Advanced Limb Functionality
In addition to walking and burrowing, Olenoides serratus possessed highly dexterous limbs well-suited for food manipulation. This way the trilobite would have been able to move food toward its mouth and produce unique trace fossils from the diverse set of movement patterns. Such versatility points to a highly evolved degree of genital plasticity to its watery environment.
“Olenoides serratus could create trace fossils of different depths using different movements,” – Sarah R. Losso.
The limbs demonstrated distinct adaptations, meaning that they were quite different from the limbs of tupuxuara like modern horseshoe crabs. Experimental studies demonstrated that O. serratus had a restricted range of limb extension, particularly distally. This implication is supported by additional evidence that its fore- and hindlimbs were adapted to distinct modes of movement.
“We found that the limbs of O. serratus had a smaller range of extension and only in the part of the limb farther from the body,” Losso added, illustrating the intricacies involved in this ancient species’ locomotion.
The Significance of Burgess Shale
The Burgess Shale is well known for the exceptional preservation of soft tissues in its fossils. It exposes features such as limbs and internal anatomy that usually disappear in other fossil beds. Specialized environmental conditions led to the quick entombment of organisms. Thanks to this advances in technology, researchers with paleontological specimens can now analyze these precious materials to unlock invaluable secrets about life on Earth’s formative years.
“We relied on exceptionally well-preserved specimens, comparing limb preservation across many angles and filling in missing details using related fossils,” said Javier Ortega-Hernández, further underscoring the significance of the Burgess Shale in paleontological research.
One of the most complete specimens, USNM PAL 65510, is a complete example with preserved antennae and limbs. Such exquisitely preserved specimens are rare and are used as important references to assemble the evolutionary history of trilobites.
More than 22,000 species of trilobites have been described so far, but fewer than 0.2% of them display any leg impressions. The new discoveries on Olenoides serratus illustrate some remarkable adaptations. They show us how little we know of other trilobite species.