A restoration of Yanliaomyzon lampreys from the Jurassic period, approximately 160 million years ago, found within the Yanliao Biota of northern China, is credited to NICE Vistudio.
A team from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) at the Chinese Academy of Sciences, in collaboration with others, has unearthed two exceedingly rare lamprey fossils from the Jurassic era in northern China, offering new insights into the evolutionary history of lampreys.
This study has been documented in the prestigious journal, Nature Communications.
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Unearthing the Fossils
The invaluable fossils were located within the renowned Yanliao Biota Lagerstätte, within strata that is between 158 to 163 million years old. Among these discoveries is the Yanliaomyzon occisor, also known as the “Yanliao sucker killer,” which measures 642 mm in length (approximately 25 inches) and represents the largest known fossil lamprey to date.
The dental structures of the Jurassic lampreys Yanliaomyzon, including Yanliaomyzon ingensdentes, meaning ‘large teeth,’ and Yanliaomyzon occisor, meaning ‘killer,’ as well as those from the contemporary Geotria australis lamprey now found in the Southern Hemisphere, are credited to NICE Vistudio and IVPP.
The fossils provide exceptional preservation of the lampreys’ keratinous teeth. The examination of these fossils led researchers to revise the previous theories concerning lamprey evolution, specifically regarding their feeding mechanisms, life cycles, and historical biogeography.
Revising Evolutionary Perspectives
The Jurassic lamprey fossils possess feeding structures remarkably similar to those of today’s flesh-feeding pouched lamprey, Geotria australis. “These Jurassic lampreys have been determined to be the closest fossil relatives to present-day lampreys,” stated WU Feixiang, the principal author of the research.
WU further explained, “Against the prevailing belief that ancestral lampreys fed on blood, our findings suggest that these Jurassic specimens were actually flesh feeders, hinting at similar dietary habits in the most recent common ancestor of today’s lampreys.”
Evolutionary Significance and Research Techniques
The research marks the Jurassic period as a pivotal moment in the evolutionary timeline of lampreys.
In the prior Paleozoic era, lampreys likely did not exhibit predatory behavior akin to their modern relatives, inferred from their smaller size and simple tooth construction. Additionally, the armored nature of other ancient fish from that time likely prevented these early lampreys from effectively preying upon them. However, the rise of ‘advanced’ teleost fish with reduced scales in the Early Jurassic signaled an increase in available prey, prompting evolutionary changes in lampreys.
The appearance of advanced teleost fishes with less dense scales during the Early Jurassic is hypothesized to have provided a significant evolutionary advantage for lampreys, according to WU. Enhanced feeding structures enabled lampreys from the Jurassic onwards to attain sizes necessary to support an elongated life cycle, which included a metamorphosis stage and adaptation to significant environmental changes.
The narrative of lamprey evolutionary history relies on a time-calibrated phylogenetic tree. The inference of lamprey evolution was conducted using a Bayesian total-evidence dating approach. ZHANG Chi, a co-author, stated, “Compared to the parsimony approach, Bayesian inference allows for the integration of multiple data sources in a probabilistic framework, addressing parameter uncertainties and avoiding partial data usage.”
Biogeographical Consequences
Such methodologies also enable the deduction of ancestral geographic distributions for lampreys. The origins of lampreys’ anti-tropical distribution pattern have perplexed biogeographers due to the sparse fossil record. With the new Jurassic lamprey data, the lineage of the pouched lamprey from the Southern Hemisphere has been identified as the earliest to diverge among living lampreys. Hence, the research posits that the modern lamprey lineage originated in the Southern Hemisphere during the Late Cretaceous, challenging the established belief of a Northern Hemisphere origin.
“This finding unequivocally points out that current southern lampreys maintain a feeding morphology established in the Jurassic and aligns modern lamprey phylogeny with a Southern Hemisphere origin, alongside an adaptation to a carnivorous lifestyle,” noted Prof. Philippe JANVIER of France’s National Museum of Natural History and co-author of the study.
Despite remaining uncertainties in the long evolutionary chronicle of lampreys, the identification of these Jurassic lamprey fossils is anticipated to spur further research.
Reference: “The rise of predation in Jurassic lampreys” by Feixiang Wu, Philippe Janvier, and Chi Zhang, dated 31 October 2023, in Nature Communications.
DOI: 10.1038/s41467-023-42251-0
Frequently Asked Questions (FAQs) about Jurassic lamprey evolution
What is the significance of the “Yanliao Sucker Killer” fossil discovery?
The “Yanliao Sucker Killer” fossil challenges previous theories on lamprey evolution, suggesting Jurassic lampreys were flesh-eaters, which impacts our understanding of their ancestral dietary habits and evolutionary history.
Where were the Jurassic lamprey fossils found?
The fossils were uncovered in the Yanliao Biota Lagerstätte of northern China, dating back to 158–163 million years ago.
How does the “Yanliao Sucker Killer” fossil alter our understanding of lamprey evolution?
This fossil, along with another, reveals that ancient lampreys had keratinous teeth similar to modern flesh-feeding species, indicating a carnivorous lineage contrary to the belief they were solely blood feeders.
What does the study suggest about the biogeographical origins of lampreys?
The study suggests that modern lampreys likely originated in the Southern Hemisphere during the Late Cretaceous, challenging the previously held view of a Northern Hemisphere origin.
How was the evolutionary history of lampreys inferred in this study?
A Bayesian total-evidence dating framework was utilized to infer the lamprey evolutionary history, which integrates multiple data sources and considers parameter uncertainties.
More about Jurassic lamprey evolution
- Yanliao Biota and Lamprey Fossil Discovery
- Jurassic Lamprey Evolution and Paleobiology
- Lamprey Evolutionary History and Phylogenetic Studies
- Biogeographical Distribution of Lampreys
- Lamprey Anatomy and Feeding Mechanisms
- Institute of Vertebrate Paleontology and Paleoanthropology (IVPP)
- Bayesian Methods in Paleontological Research
