echemi logo
Product
  • Product
  • Supplier
  • Inquiry
    Home > Food News > Nutrition News > New fossils show what the brains of arthropod ancestors looked like

    New fossils show what the brains of arthropod ancestors looked like

    • Last Update: 2021-09-04
    • Source: Internet
    • Author: User
    Search more information of high quality chemicals, good prices and reliable suppliers, visit www.echemi.com


    Image: Kaili Leanchoilia, depicted by an artist, showing its long scissor-like appendages, located behind the side eyes, on a stubby stem
    .
    14 Possessions may play a dual role-to provide oxygen to the animal and allow it to move around

    .

    The well-preserved fossils left over from creatures that lived more than 500 million years ago reveal in great detail the same structures that researchers have long hypothesized, and these structures must be part of the prototype brain inherited by all arthropods
    .
    Arthropods are the most abundant animal taxa, including insects, crustaceans, spiders, and scorpions, as well as other lesser-known branches such as millipedes and centipedes

    .

    These fossils belong to an arthropod named lechoilia, which confirms the existence of early insect and spider embryo genetics and developmental biology studies predicting the existence of an unsegmented extreme brain that cannot be seen in modern adult arthropods.
    Leaf area

    .
    Although invisible, this area of ​​the frontal lobe forms several key nerve centers in the brains of adult arthropods, including stem cells that ultimately provide decision-making and memory centers

    .
    This frontal lobe area is assumed to be different from the forebrain, midbrain, and hindbrain of existing arthropods.
    It is named forebrain, and "prosocerebrum" means "front"

    .

    A paper published today in the journal "Contemporary Biology" describes these fossils.
    The lead author of the paper, Nicholas Strathfeld, said these fossils provide the first evidence for the existence of this discrete quasi-brain region.
    , The heritage of the region appeared during the embryonic development of modern arthropods

    .
    Director Professor of Neuroscience at the University of Arizona

    .

    Strathfield said: "The extraordinary fossils we describe are never seen before
    .
    " "The two nervous systems are already unique because they are preserved in the same way

    .
    This shows that 5 Hundreds of millions of years ago, before the three segments representing the forebrain, midbrain, and hindbrain appeared, this frontmost brain region already existed, and its structure was also completely different

    .
    "

    Ganglion refers to the reticular system that forms the nerve center in each segment of the arthropod nervous system
    .
    In living arthropods, the three ganglia that mark the three parts of the brain gather together to form a solid mass, blurring their evolutionary origin into a segmented structure

    .

    Fossil brain tissue is extremely rare

    The Leanchoilia fossil remains found in the sediments of the Kaili Formation in Guizhou Province in southwestern China can be traced back to the Cambrian period about 508 million years ago
    .
    Kaili fossils appear in iron-rich sedimentary rocks.
    The presence of iron may help preserve soft tissues, which are subsequently replaced by carbon deposits

    .

    "The Kaili fossil opens a window for us, giving us a glimpse of the evolution of the body plane of animals that lived more than 500 million years ago," said Tian Lan of the Guizhou Paleontology Research Center, Guizhou University, China, the first author of the paper.
    Tian Lan) said

    .
    "We now know for the first time that the arthropod fossils of the Kaili structure have the potential to preserve nerve tissue and show us the primitive brains of early dry arthropods that existed in the dawn of the animal world

    .
    "

    "The nervous system, like other soft tissues, is difficult to turn into fossils," added Pedro Martinez, a co-author of the University of Barcelona and the Catalá Institute in Spain
    .
    "This makes studying the early evolution of the nervous system a challenging task

    .
    "

    These fossils also reveal the evolutionary origins of two different visual systems during the evolution of arthropods: a pair of frontal eyes and a pair of side-looking eyes.
    Their offspring still exist in today's species

    .

    Many arthropods, including insects and crustaceans, have a unique pair of double-sided polyhedral compound eyes and another pair of less obvious eyes, which are more primitive in structure and are called unsegmented eyes or monoculars
    .
    They are similar in structure to the main eyes of spiders and scorpions

    .
    These simpler eyes correspond to the anterior eyes of lechoilia's anterior brain, which is consistent with the evidence obtained from previous analyses of gene expression patterns during embryonic development of living arthropods

    .

    On the other hand, Leanchoilia's lateral eye is related to the front brain, which is the segmental ganglion, which defines the forebrain of arthropods and is located behind the front brain
    .
    In living arthropods, the protobrain provides the compound eyes of insects and crustaceans, or the lateral monocrystalline eyes of arachnids, centipedes, and millipedes

    .
    The visual center that serves these eyes also belongs to the original brain area of ​​the brain

    .

    Straussfeld explained that in living arthropods, the protobrain, or forebrain, has to some extent merged-swallowed-the ancient center provided by the protobrain, so it is no longer a Unique anatomical entity
    .

    These fossils are so well preserved that they show that, in addition to the front eyes, the front brain also produced ganglia associated with the lips (or "upper lip") of modern arthropods
    .
    These fossils also confirmed an earlier hypothesis that the lip-like limbs must have originally evolved from the gripping appendages of Radiodonta, a stem arthropod that was a top predator in the Cambrian

    .
    "Compared with other similar fossil materials belonging to a higher lineage, Leanchoilia's brain organization shows that the ganglion arrangement of the early brain has undergone condensation and fusion of its components, which explains why the pre-brain cannot be Separately," Straussfield said

    .

    Implications for the evolution of vertebrate brains

    Straussfeld said that in addition to filling a century of gaps in the understanding of arthropod brain evolution, these findings have important implications for the early evolution of vertebrate brains
    .

    Although these simple, fish-like animals co-exist with these now fossilized arthropods, there is no convincing fossil of their brains.
    Therefore, there is neither fossil evidence nor anatomical evidence that vertebrates have antecedents.
    Brain

    .
    However, modern research has shown that, for example, the genes that define the forebrain, midbrain, and hindbrain of mice correspond to the genes that define the three ganglion divisions of the arthropod brain

    .
    In vertebrates, certain key centers involved in decision-making, learning and memory have some genetic correspondences with the higher centers of arthropod brains, which originated in the forebrain of ancient arthropods

    .

    Therefore, it is possible that the common ancestor of vertebrates and invertebrates possessed the basic circuits of simple cognition and decision-making before the Cambrian, even before the evolution of the body plan of the segmental organization
    .
    Although there may be an ancient prebrain-like brain in the early ancestors of vertebrates, such fossils do not even provide evidence for a discrete, non-segmental area

    .

    Straussfeld said: "However, we can reasonably speculate that the'modern' brains of vertebrates have embedded parts of an ancient, unsegmented brain.
    So far, this has only been found in early arthropods (such as Leanchoilia).
    ) Was confirmed

    .
    "

    DOI 10.
    1016 / j.
    cub.
    2021.
    07.
    048

    Leanchoiliidae reveals the ancestral organization of the stem euarthropod brain


    This article is an English version of an article which is originally in the Chinese language on echemi.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to service@echemi.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

    Contact Us

    The source of this page with content of products and services is from Internet, which doesn't represent ECHEMI's opinion. If you have any queries, please write to service@echemi.com. It will be replied within 5 days.

    Moreover, if you find any instances of plagiarism from the page, please send email to service@echemi.com with relevant evidence.