Nov 5, 2020 09:03 PM
(This post was last modified: Nov 5, 2020 09:07 PM by C C.)
The grisly experiments of Jean César Legallois
https://daily.jstor.org/the-decapitation...legallois/
EXCERPTS: In the early 1800s [...] some horrified observers noted that the severed heads often took on an expression of pain—after they had been sliced from the body. This postmortem grimace fascinated most scientists, but not French physician Jean César Legallois. ... he looked at the headless trunk lying on the other side of the guillotine.
Legallois was a professional vivisectionist [...] Vivisectionists performed experiments on living animals to see how different parts of the body interacted (with a particular interest in the nervous system). ... Jean César Legallois was searching for the body’s “seat of life,” the source of its most vital functions...
[...] Legallois’s typical modus operandi involved decapitating rabbits with a tiny guillotine, cutting off their appendages [...] Sometimes, he would leave the spine intact, sometimes he would sever specific nerves. Cheung recounts one particularly cruel operation, where Legallois reduced a rabbit down to a skeleton, some muscles, and the spinal cord, laying “the basic trunk-machine of its life […] before the eyes of its observer.” Pocket watch in hand, Legallois would eyeball the duration of the trunk’s twitchy movement as each organ system shut down, and then very scientifically poke it with a needle to double-check that it was dead.
There’s more: [...] After the bodies stopped moving, he wasn’t done with them. ... “Resurrection, not healing, was his main objective.” That’s right—Legallois tried to directly “reanimate” or “resurrect” these trunks. ... Legallois would sometimes attempt to resurrect corpses through artificial inflation of the lungs. He also transplanted the organs of living animals into the dead trunks, and sometimes attempted to replace the natural circulation with fresh, oxygenated blood.
Though Legallois’s experiments may haunt your nightmares, they also fundamentally shaped physiology as we understand it today [...] Legallois created an army of horrifying zombie animals that forced us to question the meaning of the word “death.” To Legallois, it seems, “death was no longer the opposite of life,” writes Cheung, “but just a phase between one life and another.” (MORE - details)
These bizarre ancient species are rewriting animal evolution
https://www.nature.com/articles/d41586-020-02985-z
EXCERPTS: The revolutionary animal lived and died in the muck. [...] Over the next half a billion years, sediment turned to stone, preserving the deathbed scene. The fossilized creature looks like a piece of frayed rope measuring just a few centimetres wide. But it was a trailblazer among living things.
This was the earliest-known animal to show unequivocal evidence of two momentous innovations packaged together: the ability to roam the ocean floor, and a body built from segments. It was also among the oldest known to have clear front and back ends, and a left side that mirrored its right. Those same features are found today in animals from flies to flying foxes, from lobsters to lions.
Palaeontologist Shuhai Xiao marvels at the tracks left by this creature, Yilingia spiciformis [...] But that’s not the end of this creature’s story. Although nobody knows which category of life it belonged to — the group that includes earthworms is one possibility — Yilingia is helping to fill in key details about the evolution of animals. Most importantly, Yilingia shows that some quintessential animal traits had appeared half a billion years ago, earlier than previous definitive evidence, Xiao says.
Yilingia is not the only creature [...] In 2018, Xiao and his team reported on tracks ... The researchers propose that the trails were made by an animal from 550 million years ago that might have been able to burrow and had multiple pairs of appendages — which would make it one of the earliest-known animals with legs.
These Chinese fossils hail from a time right before the Cambrian explosion, the evolutionary transformation when most of the animal groups that populate the planet today first made their appearance in the fossil record. Scientists long regarded the boundary between the Cambrian period and the Precambrian as a dividing point in evolution...
[...] But a growing number of findings reveal that the time slice just before the Cambrian, known as the Ediacaran (635 million to 541 million years ago), was a pivot point of animal evolution — a period that includes the earliest fossil records of anatomical innovations, such as guts and legs, and the first appearance of complex behaviours such as burrowing. The insights into the Ediacarans’ powers lend support to a provocative idea: that the Cambrian explosion, that iconic evolutionary burst, was actually less revolutionary than many had thought.
[...] The Ediacarans’ innovations came against a backdrop of planetary cataclysms. During this time, Earth was still recovering from a long, shivery chapter when ice covered much of the seas. A gigantic meteor slammed into what is now Australia and probably kicked up enough dust to trigger catastrophic changes around the globe. The planet’s very surface was splitting: during the Ediacaran, one supercontinent broke apart and another took shape as land masses smashed together. On the continents, no plants grew. In the ocean, oxygen levels swung wildly. Scientists once thought that complex life did not start until after all this tumult... (MORE - details)
https://daily.jstor.org/the-decapitation...legallois/
EXCERPTS: In the early 1800s [...] some horrified observers noted that the severed heads often took on an expression of pain—after they had been sliced from the body. This postmortem grimace fascinated most scientists, but not French physician Jean César Legallois. ... he looked at the headless trunk lying on the other side of the guillotine.
Legallois was a professional vivisectionist [...] Vivisectionists performed experiments on living animals to see how different parts of the body interacted (with a particular interest in the nervous system). ... Jean César Legallois was searching for the body’s “seat of life,” the source of its most vital functions...
[...] Legallois’s typical modus operandi involved decapitating rabbits with a tiny guillotine, cutting off their appendages [...] Sometimes, he would leave the spine intact, sometimes he would sever specific nerves. Cheung recounts one particularly cruel operation, where Legallois reduced a rabbit down to a skeleton, some muscles, and the spinal cord, laying “the basic trunk-machine of its life […] before the eyes of its observer.” Pocket watch in hand, Legallois would eyeball the duration of the trunk’s twitchy movement as each organ system shut down, and then very scientifically poke it with a needle to double-check that it was dead.
There’s more: [...] After the bodies stopped moving, he wasn’t done with them. ... “Resurrection, not healing, was his main objective.” That’s right—Legallois tried to directly “reanimate” or “resurrect” these trunks. ... Legallois would sometimes attempt to resurrect corpses through artificial inflation of the lungs. He also transplanted the organs of living animals into the dead trunks, and sometimes attempted to replace the natural circulation with fresh, oxygenated blood.
Though Legallois’s experiments may haunt your nightmares, they also fundamentally shaped physiology as we understand it today [...] Legallois created an army of horrifying zombie animals that forced us to question the meaning of the word “death.” To Legallois, it seems, “death was no longer the opposite of life,” writes Cheung, “but just a phase between one life and another.” (MORE - details)
These bizarre ancient species are rewriting animal evolution
https://www.nature.com/articles/d41586-020-02985-z
EXCERPTS: The revolutionary animal lived and died in the muck. [...] Over the next half a billion years, sediment turned to stone, preserving the deathbed scene. The fossilized creature looks like a piece of frayed rope measuring just a few centimetres wide. But it was a trailblazer among living things.
This was the earliest-known animal to show unequivocal evidence of two momentous innovations packaged together: the ability to roam the ocean floor, and a body built from segments. It was also among the oldest known to have clear front and back ends, and a left side that mirrored its right. Those same features are found today in animals from flies to flying foxes, from lobsters to lions.
Palaeontologist Shuhai Xiao marvels at the tracks left by this creature, Yilingia spiciformis [...] But that’s not the end of this creature’s story. Although nobody knows which category of life it belonged to — the group that includes earthworms is one possibility — Yilingia is helping to fill in key details about the evolution of animals. Most importantly, Yilingia shows that some quintessential animal traits had appeared half a billion years ago, earlier than previous definitive evidence, Xiao says.
Yilingia is not the only creature [...] In 2018, Xiao and his team reported on tracks ... The researchers propose that the trails were made by an animal from 550 million years ago that might have been able to burrow and had multiple pairs of appendages — which would make it one of the earliest-known animals with legs.
These Chinese fossils hail from a time right before the Cambrian explosion, the evolutionary transformation when most of the animal groups that populate the planet today first made their appearance in the fossil record. Scientists long regarded the boundary between the Cambrian period and the Precambrian as a dividing point in evolution...
[...] But a growing number of findings reveal that the time slice just before the Cambrian, known as the Ediacaran (635 million to 541 million years ago), was a pivot point of animal evolution — a period that includes the earliest fossil records of anatomical innovations, such as guts and legs, and the first appearance of complex behaviours such as burrowing. The insights into the Ediacarans’ powers lend support to a provocative idea: that the Cambrian explosion, that iconic evolutionary burst, was actually less revolutionary than many had thought.
[...] The Ediacarans’ innovations came against a backdrop of planetary cataclysms. During this time, Earth was still recovering from a long, shivery chapter when ice covered much of the seas. A gigantic meteor slammed into what is now Australia and probably kicked up enough dust to trigger catastrophic changes around the globe. The planet’s very surface was splitting: during the Ediacaran, one supercontinent broke apart and another took shape as land masses smashed together. On the continents, no plants grew. In the ocean, oxygen levels swung wildly. Scientists once thought that complex life did not start until after all this tumult... (MORE - details)