New study finds that 540 million-year-old trilobites breathed with their legs.
A recent study published in the journal Science Advances found that 540 million-year-old trilobites (Trilobites) breathed with their legs.
According to a new imaging study led by the University of California, Riverside, trilobites had well-developed spine-like structures on the upper leg branches. Trilobites are long-extinct marine arthropods that dominated the Paleozoic ecosystem.
Trilobites appeared about 540 million years ago in the early Cambrian and disappeared in a mass extinction about 252 million years ago at the end of the Permian. They are diverse, with about 20,000 species, and their fossil exoskeletons can be found all over the world.
So far, scientists have compared the upper branches of trilobite legs with the non-respiratory upper branches of crustaceans,” said Dr. Jin-Bo Hou, a doctoral student in the Department of Earth and Planetary Sciences at the University of California, Riverside. Our paper shows for the first time that the upper branch has the function of a gill.”
Dr. Hou and his colleagues studied the pyrite remains of two trilobite species: shrug-bar trilobites (Olenoides serratus) from the Burgess Shale in Canada and trilobites (Triarthrus eatoni, a trilobite) from the Beecher Riverbed.
The trilobites lived in the Ordovician period about 450 million years ago; the shrugged stick trilobites survived in the Cambrian period about 500 million years ago.
Professor Nigel Hughes, a co-author of the study and a paleontologist in the Department of Earth and Planetary Sciences at the University of California, Riverside, said, “These “fool’s gold” preserved in pyrite are much more interesting to us than gold) is more important to us than gold because it is the key to understanding the structure of these paleontologies.” Professor Hughes is also a paleontologist at the Geological Research Unit of the Indian Statistical Institute.
A 3D schematic of a trilobite.
Using a CT scanner, the researchers created 3D models of dumbbell-shaped filaments in the upper limb branches of trilobites and trichoptera in the shrug. “This allows us to see the fossils without having to do a lot of drilling and grinding on the rocks that cover the specimens,” said Dr. Melanie Hopkins, a paleontologist in the Department of Paleontology at the American Museum of Natural History.
“In this way, we can even see what would be difficult to see under a microscope – really small trilobite anatomy, 10 to 30 microns wide.”
The researchers can also see how blood filters through the chambers in these delicate structures, drawing oxygen along the way as it moves. They look remarkably similar to the gills found in modern marine arthropods such as crabs and lobsters.
“In the past, there has been some debate about the role of these structures because the upper limb is not a good location for a respiratory apparatus,” Dr. Hopkins said.
“You would think those filaments would be easily clogged with sediment where they are, so why would they evolve that structure in that part of the body? That’s an open question.”
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