Trilobites – extinct marine arthropods that roamed the world’s oceans about 520 million years ago until they became extinct 250 million years ago, at the end of the Permian period – may have evolved in a similar fashion and reached those ages. can match existing ones in crustaceans, a new study has found.
In a paper published in the journal paleobiologyResearchers from the University of British Columbia and Uppsala University show that the Ordovician trilobite triathrus etoniAbout 450 million years ago, it reached a length of just above 4 cm in about 10 years, with a growth curve similar to that of small, slow-growing crustaceans.
,T. Eatony Daniel Pauli, UBC’s principal investigator, said crustaceans that lived in low-oxygen environments and similarly exposed to hypoxic conditions exhibited lower growth rates than those growing in more oxygen-rich conditions. the sea around us initiative and lead author of the study. “Low-oxygen environments make it more difficult for water-breathing evolution, and add difficulties to breathing through the gills, which, as 2D surfaces, cannot keep up with the evolution of their 3D bodies. Thus, under hypoxic conditions, they must remain small if they are to maintain the rest of their body functions.”
In the case of trilobites, their exopods—the outer branches on the upper side of their limbs—act as gills. Thus, these ancient animals had the same developmental constraints as their modern counterparts.
To reach these conclusions, Pauli and his colleague, paleontologist James Holmes of Uppsala University, resorted to analysis of length-frequency data, a method developed within fisheries and marine biology to study the evolution of fish and invertebrates. Method that lacks physical markings that indicate their age.
The information to analyze them was derived from an earlier publication with information on the length-frequency distribution of 295 exceptionally-preserved trilobite fossils collected at ‘Beecher’s Trilobite Beds’ in New York State.
After assessing the parameters of a growth model widely used in fisheries science, the von Bertalanffy growth function, the researchers compared their results with published data on the evolution of extant crustaceans. He found that the growth criteria he estimated triathrus etoni Until recently were within the range of slow-growing crustaceans.
“These findings provide the first reasonable estimate of absolute growth in early animals using methods known to accurately characterize growth in comparable living species,” Holmes said. “They show us that about half a billion years ago, the growth in marine arthropods such as trilobites was similar to modern examples such as the crustaceans that live in today’s oceans.”
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