The discovery of fossils sheds light on the early evolution of animal nervous systems https://ift.tt/NiXY57k Incomplete specimens of Epriapulite sphinx tube showing their ventral nerve cords from the Early Cambrian Quanchuanpu Formation. Credit: Science Advances (2025). DOI: 10.1126/sciadv.adr0896 An international team of scientists has uncovered an intriguing piece of the evolutionary puzzle: how the ventral nerve cord, a key component of the central nervous system, evolved in ecdyzozoans, including insects, nematodes and priapulid worms. Their findings are published in the paper “Preservation and Early Evolution of the Scalidophora Ventral Nerve Cord.” Science Advancesprovides valuable insights into the origin of these formations in the basal Cambrian. A research team consisting of Dr. Deng Wang (Northwestern University), Dr. Jean Vannier (Université de Lyon), Dr. Chema Martin-Duran (Queen Mary University of London) and Dr. Maria Errantz (University of Rey Juan Carlos) discovered exceptionally well-preserved fossils from the main Cambrian deposits. analyzed. These fossils include early-evolved members of the small group of ecdyzoans called Scalidophora, which rarely show the architecture of the nervous system of ancient animals. Ecdyzozoans include arthropods (such as insects and crabs), nematodes (roundworms), and smaller groups such as cynorrhynx (“mud dragons”) and priapulids (“penis worms”). Their central nervous systems, including the brain and ventral nerve cords, have long fascinated scientists. evolutionary relationships between these groups. For example, priapulids have a single ventral nerve cord, while lauriferans and kinorhynchs have paired nerve cords, and kynorhynchs also develop paired ganglia. Did ancestral ecdyzoans have one or a pair of ventral nerve cords? Furthermore, while loriciferans and kinorhynchs share similar nervous systems with arthropods, they are phylogenetically distant. Are these similarities the result of convergent evolution or do they reflect a common evolutionary origin? Scalidophorans, including priapulids, lauriferans, and cynorrhynches, first appeared in the early Cambrian. They represent an important lineage for studying the evolutionary trajectory of ventral nerve cords in ecdyzoans. By examining fossils from the Fortunian Kuanchuanpu Formation (such as Eopriapulites and Eokinorhynchus), the Chengjiang Biota (such as Xiaoheiqingella and Mafangscolex), and the Wuliuan Ottoia prolifica, the researchers identified elongated structures along the ventral side of the ancient organisms. “These structures resemble ventral nerve cords seen in modern priapulids,” explained Dr. Deng Wang and Dr. Jean Vannier. Their analysis shows that these fossils shed light on the probable ancestral state of scalidophorans, preserving impressions of a single ventral nerve cord. Phylogenetic analysis supports the hypothesis that there was a single ventral nerve cord ancestral to scalidophorans. In addition, the evolutionary group of nematodes and panarthropods (which includes arthropods, tardigrades, and onychophorans) is characterized by their common father It can also be a nerve fiber. “This leads us to believe that the common ancestor of all ecdyzoans shared a single ventral nerve cord,” said Dr Chema Martin-Duran. “Paired nerve cords observed in arthropods, lauriferans, and cynorrhynches likely evolved independently and represented derived traits.” Discover the latest news in science, technology and space 100,000 subscribers who rely on Phys.org for daily insight. Register on our page free newsletter and receive updates on important discoveries, innovations and research—daily or weekly. The study also highlights the relationship between paired ventral nerve cords, ganglia, and the evolution of body segmentation. Loriciferans, kinorhynchs and panarthropods show different degrees of body segmentation, suggesting that these structural changes may have evolved along with changes in the nervous system. Dr. Maria Herranz noted: “The formation of paired nerve fibers probably facilitated the coordination of movement, especially in segmented animals. Changes in the nervous and muscular systems during the transition from the Precambrian to the Cambrian period were probably related to the development of appendages. Complex movement” . This discovery enriches our understanding of ecdyzoan evolution and highlights the role of the fossil record in solving fundamental questions about early animal development. By linking the structures of the nervous system to broader evolutionary trends, the study sheds light on how different ecdyzozoan lineages arose and adapted to their environments. More information: Dan Wang, Preservation and early evolution of ventral nerve cords in Scalidophora, Science Advances (2025). DOI: 10.1126/sciadv.adr0896. https://ift.tt/gLiPCqp provided by Queen Mary, University of London Quote: Fossil discovery sheds light on early evolution of animal nervous systems (2025, January 10) Retrieved January 10, 2025 from https://ift.tt/vrjJU2g This document is subject to copyright. No part may be reproduced without written permission except for any fair dealing for personal study or research purposes. Content is provided for informational purposes only. #discovery #fossils #sheds #light #early #evolution #animal #nervous #systems https://ift.tt/v3hPUGS
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