Researchers have discovered the earliest known cephalopod fossil in southern Shaanxi Province, pushing the origin of the predatory mollusc back roughly 30 million years to the early Cambrian period about 520 million years ago, according to a study published in Nature.
Unearthing the Earliest Cephalopod Fossil in Shaanxi
A research team led by Guo Junfeng from Chang’an University in Xi’an uncovered the millimeter-scale fossil within the Shuijingtuo Formation. According to the study, the specimen features a straight, conical shell that bridges a major evolutionary gap in the fossil record. Prior to this finding, the earliest universally accepted cephalopod fossils dated to the late Cambrian, roughly 490 million years ago. That timeline created a stark mismatch with molecular clock estimates, which consistently placed the initial divergence of cephalopods—the lineage containing squids, octopuses, and nautiluses—firmly in the early Cambrian.
Redefining Early Cambrian Evolution and Tubular Fossils
The discovery validates molecular clock inferences by capturing physical evidence of the group during its predicted emergence window. Based on detailed analysis of the specimen, Guo stated that the research team proposed a new hypothesis regarding ancestral anatomy: cephalopods may have originated from straight, tubular shelled forms possessing multiple septa. This morphological link offers paleontologists a fresh framework for reinterpreting the vast array of mysterious tubular fossils left behind by the Cambrian explosion.
Did you know? The emergence of the siphuncle—a tubular structure running through the shell chambers—is regarded by scientists as the key biological innovation that marked the divergence of cephalopods from basal mollusks, allowing them to control buoyancy and become active predators.
Frequently Asked Questions
When did the newly discovered cephalopod fossil live?
The fossil dates back roughly 520 million years to the early Cambrian period, according to research published in Nature.
Who led the research team that made the discovery?
The study was led by Guo Junfeng from Chang’an University in Xi’an, working with colleagues who explored strata in southern Shaanxi Province.
Why is this fossil significant to evolutionary biology?
According to the published study, the find extends the empirical fossil record of cephalopods by about 30 million years, closing the gap between physical fossils and molecular clock estimates.
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