Shuyu 3D puzzle. Credit: IVPP
The human middle ear, home to three small vibrating bones, is essential for transmitting sound vibrations to the inner ear, where they become nerve impulses that allow us to hear.
Embryonic and fossil evidence prove that the human middle ear arose from the miracle fish. However, the origin of vertebrate stigma has long been an unresolved mystery in vertebrate evolution.
“These fossils provided the first anatomical and fossil evidence of a vertebrate horizontal miracle of fish gills.” – Professor GAI Zhikun
about twentye Horn researchers, believing that early vertebrates should possess a complete spiny gill, searched for one between the mandibular and hyoid arches of early vertebrates. Despite extensive research spanning over a century, none have been found in vertebrate fossils.
Now, however, scientists from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences and their collaborators have found evidence of this mystery from the fossils of armored galeaspidae in China.
Their findings were published in the journal Frontiers in Ecology and Evolution May 19, 2022.
According to Professor GAI Zhikun of IVPP, first author of the study, researchers at the institute have discovered the 438 million-year-old creature in a row over the past 20 years. شويو 3D jigsaw puzzle and first fully preserved 419-million-year-old fossil with gill filaments in first gill chamber. The fossils were found in Changxing, Zhejiang Province, and Qujing, Yunnan Province, respectively.
Shuyu’s 3D virtual reconstruction. Credit: IVPP
“These fossils provided the first anatomical and fossil evidence of a vertebrate horizontal prodigy from fish gills,” GAI said.
A total of seven hypothetical endings of شويو Then the puzzles were reconstructed. Almost every detail of the anatomy of the skull شويو It was revealed in his fingernail-size skull, including five brain sections, sensory organs, cranial nerve pathways, and cranial blood vessels.
“Many important structures for humans can be traced back to our fish ancestors, such as our teeth, jaws, middle ears, etc. The main task of paleontologists is to find important missing links in the evolutionary chain from fish to man. شويو It was considered a missing link no less important than ArcheopteryxAnd Ichthyostega And Realsaid ZHU Min, an academician with the Chinese Academy of Sciences.
The first fossil of a 419-million-year-old gallipid with gill filaments in the first gill chamber. Credit: IVPP
The miracle is a small hole behind each eye that opens into the mouth of some fish. In sharks and all rays, the miracle is responsible for introducing water into the mouth space before it is expelled from the gills. The miracle is often located at the top of the animal allowing it to breathe even when the animal is mostly buried under sediment.
In the multi-winged, which are the most primitive living bony fish, use vents to breathe air. However, the respiratory openings of fish were eventually replaced in most non-fish species as they evolved to breathe through their noses and mouths. Initially[{”attribute=””>tetrapodsthespiracleseemstohavefirstdevelopedintotheOticnotchLikethespiracleitwasusedinrespirationandwasincapableofsensingsoundLaterthespiracleevolvedintotheearofmoderntetrapodseventuallybecomingthehearingcanalusedfortransmittingsoundtothebrainviatinyinnerearbonesThisfunctionhasremainedthroughouttheevolutiontohumans[{”attribute=””>tetrapodsthespiracleseemstohavedevelopedfirstintotheOticnotchLikethespiracleitwasusedinrespirationandwasincapableofsensingsoundLaterthespiracleevolvedintotheearofmoderntetrapodseventuallybecomingthehearingcanalusedfortransmittingsoundtothebrainviatinyinnerearbonesThisfunctionhasremainedthroughouttheevolutiontohumans
“Our finding bridges the entire history of the spiracular slit, bringing together recent discoveries from the gill pouches of fossil jawless vertebrates, via the spiracles of the earliest jawed vertebrates, to the middle ears of the first tetrapods, which tells this extraordinary evolutionary story,” said Prof. Per E. Ahlberg from Uppsala University and academician of the Royal Swedish Academy of Sciences.
Reference: “The Evolution of the Spiracular Region From Jawless Fishes to Tetrapods” by Zhikun Gai, Min Zhu, Per E. Ahlberg and Philip C. J. Donoghue, 19 May 2022, Frontiers in Ecology and Evolution.
DOI: 10.3389 / fevo.2022.887172