. 24/7 Space News .
EARLY EARTH
New fossils show what the ancestral brains of arthropods looked like
by Staff Writers
Tucson AZ (SPX) Aug 23, 2021

An artist's depiction of a Kaili Leanchoilia showing its long scissor-like appendages situated behind sideward eyes on stubby stalks. Fourteen pairs of appendages likely served a double role - providing the animal with oxygen and allowing it to move about.

Exquisitely preserved fossils left behind by creatures living more than half a billion years ago reveal in great detail identical structures that researchers have long hypothesized must have contributed to the archetypal brain that has been inherited by all arthropods. Arthropods are the most diverse and species-rich taxonomic group of animals and include insects, crustaceans, spiders and scorpions, as well as other, less familiar lineages such as millipedes and centipedes.

The fossils, belonging to an arthropod known as Leanchoilia, confirm the presence - predicted by earlier studies in genetics and developmental biology of insect and spider embryos - of an extreme frontal domain of the brain that is not segmented and is invisible in modern adult arthropods. Despite being invisible, this frontal domain gives rise to several crucial neural centers in the adult arthropod brain, including stem cells that eventually provide centers involved in decision-making and memory. This frontal domain was hypothesized to be distinct from the forebrain, midbrain and hindbrain seen in living arthropods, and it was given the name prosocerebrum, with "proso" meaning "front."

Described in a paper published in the journal Current Biology, the fossils provide the first evidence of the existence of this discrete prosocerebral brain region, which has a legacy that shows up during the embryonic development of modern arthropods, according to paper lead author Nicholas Strausfeld, a Regents Professor of Neuroscience at the University of Arizona.

"The extraordinary fossils we describe are unlike anything that has been seen before," Strausfeld said. "Two nervous systems, already unique because they are identically preserved, show that half a billion years ago this most anterior brain region was present and structurally distinct before the evolutionary appearance of the three segmental ganglia that denote the fore-, mid- and hindbrain."

The term ganglion refers to a system of networks forming a nerve center that occurs in each segment of the nervous system of an arthropod. In living arthropods, the three ganglia that mark the three-part brain condensed together to form a solid mass, obscuring their evolutionary origin as segmented structures.

Fossils of Brain Tissue are Extremely Rare
Discovered in deposits of the Kaili formation - a geological formation in the Guizhou province of southwest China - the fossilized remains of Leanchoilia date back to the Cambrian period, about 508 million years ago. The Kaili fossils occur in sedimentary rock that has high concentrations of iron, the presence of which probably helped preserve soft tissue, which subsequently was replaced by carbon deposits.

"The Kaili fossils open a window for us to glimpse the body plan evolution of animals that lived more than half a billion years ago," said the paper's first author, Tian Lan of the Guizhou Research Center for Palaeobiology at Guizhou University in China. "For the first time, we now know that arthropod fossils of the Kaili formation have the potential to preserve neural tissue that show us the primitive brain of the early stem arthropod existing at the dawn of the animal world."

"Nervous systems, as other soft tissues, are difficult to fossilize," added co-author Pedro Martinez of the Universitat de Barcelona and Institut Catala in Barcelona, Spain. "This makes the study of the early evolution of neural systems a challenging task."

The fossils also shed new light on the evolutionary origin of two separate visual systems in arthropod evolution: pairs of front-facing eyes or sideward looking eyes, the descendants of which are still present in species living today.

Many arthropods, including insects and crustaceans, have a distinct bilateral pair of faceted compound eyes and another set of less obvious eyes - with more primitive architecture - known as nauplius eyes, or ocelli. These are structurally similar to the principal eyes of spiders and scorpions. These simpler eyes correspond to the prosocerebrum's forward eyes in Leanchoilia, in line with evidence obtained by previous studies analyzing gene expression patterns during embryonic development of living arthropods.

Leanchoilia's sideward eyes, on the other hand, relate to the protocerebrum, which is the segmental ganglion defining the arthropod forebrain, lying just behind the prosocerebrum. In living arthropods, the protocerebrum provides the compound eyes of insects and crustaceans, or the lateral single-lens eyes of arachnids, centipedes and millipedes. The visual centers serving those eyes also belong to the brain's protocerebral region.

Strausfeld explained that in living arthropods, the protocerebrum, or forebrain, has incorporated - in a way, swallowed up - the ancient centers provided by the prosocerebrum, so that it is no longer discernible as a distinct anatomical entity.

The fossils are so well-preserved that they demonstrate that in addition to frontward eyes, the prosocerebrum has also given rise to ganglia associated with the labrum, or "upper lip," of modern arthropods. The fossils also confirm an earlier hypothesis suggesting that the labrum must have originally evolved from the grasping appendages of Radiodonta, a group of stem-arthropods that were top predators during the Cambrian period.

"When compared with other, similar fossil material belonging to more advanced lineages, the organization of the Leanchoilia brain demonstrates that the ganglionic arrangement of the early brain underwent condensation and fusion of its components, which explains why in living species the prosocerebrum cannot be individually distinguished," Strausfeld said.

Implications for Brain Evolution in Vertebrates
In addition to closing a century-old gap in the understanding of arthropod brain evolution, the findings have important implications for the early evolution of vertebrate brains, Strausfeld said.

Although simple, fishlike animals existed at the same time as these now-fossilized arthropods, there are no convincing fossils of their brains and, thus, neither fossil evidence nor anatomical evidence for a prosocerebrum in vertebrates. Yet, modern studies show that genes defining the fore- mid- and hindbrains of, for example, mice correspond to genes defining the three ganglionic divisions of the arthropod brain. And in vertebrates, certain crucial centers involved in decision making and in learning and memory have some genetic correspondences with the higher centers in the arthropod brain, which originated in the ancient arthropod prosocerebrum.

Thus, it is plausible that even earlier than the Cambrian period, possibly even before the evolution of segmentally organized body plans, the common ancestor of both vertebrates and invertebrates possessed basic circuits for simple cognition and decision making. And while an ancient prosocerebral-like brain might have been present in the very early ancestors of vertebrates, no such fossil has even suggested evidence for a discrete, nonsegmental domain.

"Nevertheless, one can reasonably speculate that vertebrates have embedded in their 'modern' brains parts of an ancient, non-segmented brain that has so far only been demonstrable in an early arthropod, such as Leanchoilia," Strausfeld said.

Additional co-authors on the study are Yuanlong Zhao of the Guizhou Research Center for Palaeobiology at Guizhou University in Guiyang, China; Fangchen Zhao of the State Key Laboratory of Palaeobiology and Stratigraphy of the Chinese Academy of Sciences in Nanjing, China; and You He of Shanghai Synchrotron Radiation Facility.

Research Report: "Leanchoiliidae reveals the ancestral organization of the stem euarthropod brain"


Related Links
University Of Arizona
Explore The Early Earth at TerraDaily.com


Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Monthly Supporter
$5+ Billed Monthly


paypal only
SpaceDaily Contributor
$5 Billed Once


credit card or paypal


EARLY EARTH
Hobbit creature suggests rapid evolution of mammals after dinosaur extinction
Boulder CO (SPX) Aug 19, 2021
Research published in the peer-reviewed Journal of Systematic Palaeontology describes the discovery of three new species of ancient creatures from the dawn of modern mammals, and hints at rapid evolution immediately after the mass extinction of the dinosaurs. These prehistoric mammals roamed North America during the earliest Paleocene Epoch, within just a few hundred thousand years of the Cretaceous-Paleogene boundary that wiped out the dinosaurs. Their discovery suggests mammals diversified more ... read more

Comment using your Disqus, Facebook, Google or Twitter login.



Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

EARLY EARTH
NASA seeks student tech ideas for suborbital launch

Samsung announces $205 billion investment plan

Northrop Grumman set to launch 16th cargo delivery mission to ISS

NASA, Boeing to Move Starliner to Production Facility for Propulsion System Evaluation

EARLY EARTH
Musk says next Moon landing will probably be sooner than in 2024

Boeing to remove Starliner from rocket, months-long delay expected

Boeing Starliner launch faces further delays

Hermeus fully-funded to flight with US Air Force Partnership

EARLY EARTH
NASA's Ingenuity helicopter completes 12th Mars flight

Trio of orbiters shows small dust storms help dry out Mars

Aviation Week awards NASA's Ingenuity Mars Helicopter with laureate

Is Curiosity exploring surface sediments or lake deposits

EARLY EARTH
Chinese astronauts to conduct extravehicular activities for second time

Mars mission outcomes to advance space research

Chinese rocket for Tianzhou-3 mission arrives at launch site

Tianhe astronauts use free time to watch ping-pong and exercise

EARLY EARTH
Microsoft unveils Australian Space Startup launchpad

Phantom Space acquires Micro Aerospace Solutions

Business growth scheme open to next group of space entrepreneurs

BlackSky to expand constellation with three back-to-back missions

EARLY EARTH
Facebook unveils virtual reality 'workrooms'

A technique to predict radiation risk during ISS Missions

DRCongo to review China Moly copper-cobalt mine deal

Department of Energy invests in novel research in high-performance algorithms

EARLY EARTH
Did nature or nurture shape the Milky Way's most common planets

New ESO observations show rocky exoplanet has just half the mass of Venus

Small force, big effect: How the planets could influence the sun

Astronomers find evidence of possible life-sustaining planet

EARLY EARTH
A few steps closer to Europa: spacecraft hardware makes headway

Juno joins Japan's Hisaki satellite and Keck Observatory to solve "energy crisis" on Jupiter

Hubble finds first evidence of water vapor on Ganymede

NASA Awards Launch Services Contract for the Europa Clipper Mission









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.