A new “most ancient” human ancestor has been discovered. The earliest human ancestors may have had tentacles Evolutionary theory: human ancestors

In China, the remains of primitive multicellular creatures have been found that claim to be the most ancient ancestors of humans, other vertebrates and sea urchins.

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Most modern groups and types of animals appeared approximately 540-520 million years ago, during the “Cambrian explosion”, a sharp ancestor of worms, insects, fish and other vertebrates. Degang Shu from Northwestern University in Xi'an studied deposits of unusual shale in Shanxi province, formed about 520-510 million years ago. The deposits were formed at the bottom of the Earth's primary ocean in the almost complete absence of oxygen, thanks to which they preserved imprints of even the softest body tissues of ancient animals.

As reported in an article published in the journal Nature, in these rocks Chinese paleontologists found the remains of an extremely unusual animal - a small oval structure one millimeter long, similar to a bag with “toothy” edges. Scientists named it Saccorhytus coronarius, which translates to "wrinkled sac with a crown." Later it turned out that the find is the most ancient deuterostome animal.

According to paleontologists, Saccorhytus coronarius had some kind of gills, traces of which can be seen in the form of strange conical structures on its skin. Through them the “bag” released water, which he swallowed along with food. Later, these cones could turn into gill arches, and then into the jaws and nose of the first fish, marking the beginning of the evolution of man, who would appear on Earth 519.8 million years after the “tooth bags” entered the Cambrian shale record.

Let us remind you that earlier scientists from Britain and Canada were able to prove the presence of a bird that reached a length of only five centimeters. Experts studied the fossilized remains of 114 representatives of this species and presented to the public evidence that the worm was the ancestor of all representatives of the chordate phylum.

The conclusions of experts are reported in the scientific journal Biological reviews. The authors of the note were Cambridge University professor Simon Conway Morris and Canadian paleontologist Jean-Bernard Caron from the University of Toronto. "The remains of primitive chordates are a very rare find. Due to the lack of a spinal cord and other bone structures that could be fossilized, creatures like the pikaia had virtually no chance of leaving evidence of their existence for posterity," Caron said.

“However, in the unique conditions of the Burgess Shale, this was possible. We hope that further research, both in the field and in the laboratory, will reveal new species that will shed light on the history of human origins,” he added.

KurskCity reports that scientists used an electron microscope for their research for the first time, as well as photography in polarized light. This made it possible to establish the smallest details of the anatomy of the ancient worm. In particular, a notochord, neural tube, myomeres, and even remnants of the circulatory system were found in Pikaia. Let us remember that the fossils of the ancient creature were first discovered in 1911 by the American paleontologist Charles Walcott.

Previously, scientists from Russia confirmed the theory that the common ancestor of all living creatures that had bilateral body symmetry, which also includes humans, had appendages that helped them move and collect food, that is, tentacles. Doctor of Biological Sciences Elena Temereva devoted her research to this, and its results were published in the journal PLOS ONE. The scientist’s co-author was Evgeniy Tsitrin, a researcher at the Institute of Biology of the Russian Academy of Sciences.

Biologists have studied the lingula, the oldest brachiopods that have survived to this day and belong to bilaterally symmetrical animals that have lophophores, which are special parts of the body in the form of tentacles.

Temereva was able to discover similarities in the structure of the nervous systems in different groups of lophophoric living creatures, which led her to the conclusion that they have a single ancestor. “Due to the fact that there are tentacles in the two main trunks of bilaterally symmetrical animals, it is logical to assume that the common ancestor also had them...”, the scientist argues. “The common ancestor of chordates, which includes humans, also had tentacles,” concluded Elena Temereva.

This article will focus on the ancestors and closest relatives of modern man.

The topic is interesting and yet simple.

Dryopithecus

– literal translation: “tree monkeys”

Common ancestor of modern humans and apes. They lived about 25 million years ago in Africa and Europe.

Outwardly, most likely, they were similar to modern chimpanzees.

Dryopithecus lived in herds, mainly in trees.

Due to the “arboreal” life, Dryopithecus and its descendants have some peculiarities:

forelimbs can rotate in all directions

This lifestyle was important for evolution:

the grasping function of the forelimb developed, which subsequently led to the ability to manipulate objects

improved coordination, developed binocular color vision, life in the herd gave rise to the emergence of the public and, ultimately, to the emergence speeches;
Obrain volume clearly more than that of our ancestors;
at had teeth thin layer of enamel, which suggeststhat Dryopithecus ate plant foods (fruits, berries).

Australopithecus

-transitional form from ape to man (or possibly relatives of the transitional form).

They lived about 5.5 million years ago.

Literal translation: “southern monkeys”, so named because its remains are found in southern Africa.

Australopithecines are already more “humanized” monkeys.

They walked on their hind legs, slightly hunched over.

they began to use primitive “tools”: stones, sticks, etc.
the volume of the brain was approximately 400-520 cm 3, which is three times less than the volume of the modern human brain, but slightly larger than the brain volume of modern large apes;
They were not tall: 110 – 150 cm, weight: 20 – 50 kg.
Australopithecus ate both plant and meat (less commonly).
they knew how to hunt using “tools”;
life expectancy was short: 18 – 20 years;

Homo habilis (Homo habilis)

- possibly the first representative of the human race

According to an alternative opinion, Homo habilis is a representative of Australopithecus, since in appearance he is very similar to them.

Lived about 2 million years ago.

Possibly a descendant of one of the species of Australopithecus. Skillful named because started making and consciously use tools. He selected raw materials for the manufacture of tools, which no animal can boast of.

the volume of the brain, compared to Australopithecus, increased to approximately 600 cm 2, the facial part of the face of the skull decreased, “giving way” to the brain part;
teeth smaller than those of australopithecines.
the skilled man switched to euryphagy (omnivorous);
the feet had an arch and became more adapted to walking on the hind limbs;
the hand has become more adapted to grasping, the gripping power has increased;
The larynx was not yet adapted for speech, but the part of the brain responsible for this function was already developed.

Homo erectus

- already definitely a representative of the human race.

Lived approximately 1 million - 300 thousand years ago.

It is named so, as you might guess, because of the “final transition” to upright walking.

he was already characterized by “human” qualities: speech and abstract thinking;
Homo erectus has stepped far forward: his tools have become much more complex, he has mastered fire, some scientists suggest that he could even extract it on his own;
Outwardly, Erectus was a little similar to modern man, but still different from him: scull had thick walls, the forehead was low with massive supraorbital protrusions, large, heavy lower jaw, the chin protrusion is slightly prominent;
sexual dimorphism was less pronounced than in australopithecines, but still occurred: males were slightly larger than females.
height was 150 - 180. Brain volume: approximately 1100 cm 3.

Homo erectus lived a hunter-gatherer lifestyle. They lived and hunted in groups - this helped in the development of speech and sociality. It is assumed that Homo erectus was supplanted by Neanderthal 300 thousand years ago, but recent anthropological data reject this.

Pithecanthropus(translated: ape man)

– a type of Homo erectus.

Lived in Southeast Asia 500-700 thousand years ago, was first discovered on the island of Java.

Pithecanthropus is not the ancestor of modern man, but rather our cousin.

Sinanthropus

- another variety of Homo erectus.

Lived 600-400 thousand years ago somewhere in the territory of modern China.

Sinanthropus became one of the last most developed representatives of the Homo erectus species. Some scientists are considered to be the ancestors of modern humans.

Neanderthal, Neanderthal Man

- a species of the human genus, previously considered a subspecies of Homo sapiens.

Lived in Europe and North Africa over 100 thousand years ago.

Neanderthals had a hard time, they lived during the Ice Age, so it’s no wonder that they learned to make houses and clothes. Neanderthals ate primarily meat. Neanderthal not a direct ancestor of Homo sapiens, although he may have lived next to the Cro-Magnons and could freely interbreed with them, thus leaving his “genetic trace” in modern representatives of the Human genus. It is also believed that there was a struggle between Cro-Magnons and Neanderthals, as a result of which the latter probably disappeared. It is likely that Cro-Magnons could hunt Neanderthals, and vice versa. Neanderthals were large, muscular creatures, more massive than Cro-Magnons.

Neanderthal brain volume was 1200-1600 cm³.
height: about 1.5 meters;
the skull was elongated back (due to the large brain), but the forehead was low, the cheekbones were wide, the jaws were large, the chin, like that of the erectus, was weakly defined;
the brow ridge protruded noticeably;
Neanderthals developed a culture: the first religion (they buried their brothers in special rituals), a musical instrument;
Medicine began to appear: Neanderthals could treat fractures.

Cro-Magnon

- the first representative of the species Homo sapiens, lived about 40 thousand years ago.

Cro-Magnons had a definitively human appearance: a high, straight forehead, the brow ridge disappeared, and a chin protrusion appeared;
Cro-Magnons were taller (height was about 180 cm) and less massive than Neanderthals;
brain volume: 1400-1900 cm 3
possessed articulate speech, formed the first “real” human society;
The Cro-Magnons lived in tribal communities of 100 people, creating the first settlements. They built dwellings: huts made of skins, dugouts. They made clothing, hunting tools: spears, snares, harpoons, and household items: knives, needles, scrapers. They were engaged in farming. They hunted collectively, using a revolutionary method: driven hunting. They began to domesticate animals;
were highly developed culturally: they were engaged in rock painting and made sculptures from clay.

Just like the Neanderthals, they developed burial rituals, from which we can conclude that both believed in an afterlife. According to official science,Cro-Magnon is the direct ancestor of modern humans.

It took nature many millions of years to transform the monkey into modern man - the crown of creation. We are the result of a long evolutionary process, which we have just briefly skimmed over. Questions on this topic may appear in the State Examination Agency and the Unified State Examination. And we looked at this topic, I hope you found it interesting.

Scientists have not been able to come to a consensus about who the ancestors of people are; debates in scientific circles have been going on for more than a century. The most popular is the evolutionary theory proposed by the famous Charles Darwin. Taking it as true that man is a “descendant” of the ape, it is interesting to trace the main stages of evolution.

Evolutionary Theory: Human Ancestors

As already mentioned, most scientists are inclined to agree with the evolutionary version that explains the ancestors of people, if you rely on this theory, are apes. The transformation process took over 30 million years, the exact figure has not been established.

The founder of the theory is Charles Darwin, who lived in the 19th century. It is based on factors such as natural selection and hereditary variability.

Parapithecus

Parapithecus is the common ancestor of humans and monkeys. Presumably these animals inhabited the earth 35 million years ago. These are the ones that are currently considered the initial link in the evolution of apes. Dryopithecus, gibbons and orangutans are their “descendants”.

Unfortunately, scientists know little about ancient primates; the data was obtained through paleontological finds. It was found that tree monkeys preferred to settle in trees or open spaces.

Dryopithecus

Dryopithecus is an ancient human ancestor, descended, according to available data, from Parapithecus. The time of appearance of these animals is not precisely established; scientists suggest that this happened approximately 18 million years ago. Semi-terrestrial apes gave rise to gorillas, chimpanzees and australopithecines.

A study of the structure of the animal’s teeth and jaw helped establish that Dryopithecus can be called the ancestor of modern humans. The material for the study was the remains found in France in 1856. It is known that the hands of Dryopithecus allowed them to grab and hold objects, as well as throw them. Apes settled primarily in trees and preferred a herd lifestyle (protection from attacks by predators). Their food consisted mainly of fruits and berries, which is confirmed by the thin layer of enamel on the molars.

Australopithecus

Australopithecus is a highly developed ape-like ancestor of man who inhabited the earth presumably about 5 million years ago. The monkeys used their hind limbs to move and walked in a semi-erect position. The height of the average australopithecus was 130-140 cm; taller or shorter individuals were also found. Body weight also varied - from 20 to 50 kg. It was also possible to establish the volume of the brain, which was approximately 600 cubic centimeters, this figure is higher than that of apes living today.

Obviously, the transition to upright posture led to the release of the hands. Gradually, the predecessors of man began to master primitive tools used to fight enemies and hunt, but they had not yet begun to manufacture them. The tools used were stones, sticks, and animal bones. Australopithecus preferred to live in groups, as this helped to effectively defend against enemies. Food preferences were different; not only fruits and berries were used, but also animal meat.

Outwardly, Australopithecus looked more like apes than humans. Their bodies had thick hair.

A skilled man

Homo habilis was practically no different in appearance from Australopithecus, but was significantly superior to it in development. It is believed that the first representative of the human race appeared approximately two million years ago. The remains were first found in Tanzania in 1959. The brain volume possessed by Homo habilis exceeded that of Australopithecus (the difference was approximately 100 cubic centimeters). The height of the average individual did not exceed 150 cm.

These descendants of Australopithecines earned their name primarily because they began to make primitive tools. The products were mainly stone and were used during hunting. It was possible to establish that meat was constantly present in the diet of Homo habilis. A study of the biological features of the brain allowed scientists to assume the possibility of speech rudiments, but this theory has not received direct confirmation.

Homo erectus

The settlement of this species occurred approximately a million years ago; the remains of Homo erectus were discovered in Asia, Europe, and Africa. The brain volume possessed by representatives of Homo erectus was up to 1100 cubic centimeters. They were already capable of making signal sounds, but these sounds still remained inarticulate.

Homo erectus is known primarily for its success in collective activity, which was facilitated by an increase in brain volume compared to previous stages of evolution. Human ancestors successfully hunted large animals and learned to make fire, as evidenced by piles of charcoal found in caves, as well as charred bones.

Homo erectus had the same height as Homo habilis and was distinguished by the archaic structure of the skull (low frontal bone, sloping chin). Until recently, scientists believed that representatives of this species disappeared about 300 thousand years ago, but recent discoveries refute this theory. It is possible that Homo erectus saw the appearance

Neanderthals

Not long ago it was assumed that Neanderthals were the direct ancestors. However, recent evidence suggests that they represent a dead-end evolutionary branch. Representatives of Homo neanderthalensis had a brain whose volume was approximately equal to the volume of the brain endowed with modern people. Outwardly, Neanderthals no longer resembled monkeys; the structure of their lower jaw indicates the ability to articulate speech.

It is believed that Neanderthals appeared about 200 thousand years ago. The places of residence they chose depended on the climate. These could be caves, rocky overhangs, river banks. The tools that Neanderthals made became more advanced. The main source of food remained hunting, which was practiced in large groups.

It was possible to find out that Neanderthals had certain rituals, including those associated with the afterlife. It was among them that the first rudiments of morality arose, expressed in concern for their fellow tribesmen. The first timid steps were taken in such a field as art.

Homo sapiens

The first representatives of Homo sapiens appeared approximately 130 thousand years ago. Some scientists suggest that this happened even earlier. Externally, did they look almost the same? just like the people inhabiting the planet today, the volume of the brain did not differ.

Artifacts found as a result of archaeological excavations make it possible to assert that the first people were highly developed from a cultural point of view. This is evidenced by such finds as cave paintings, various jewelry, sculptures and engravings created by them. It took Homo sapiens approximately 15 thousand years to populate the entire planet. The improvement of tools led to the development of a productive economy; such activities as animal husbandry and agriculture became popular among Homo sapiens. The first large settlements belong to the Neolithic era.

Humans and monkeys: similarities

The similarities between humans and apes are still the subject of research. Monkeys are able to move on their hind limbs, but use their arms as support. The fingers of these animals do not contain claws, but nails. The number of ribs of an orangutan is 13 pairs, while representatives of the human race have 12. The number of incisors, canines and molars in humans and monkeys is the same. It is also impossible not to note the similar structure of organ systems and sensory organs.

The similarities between humans and apes become especially clear when we consider the ways of expressing feelings. They demonstrate sadness, anger, and joy in the same way. They have a developed parental instinct, which manifests itself in caring for the cubs. They not only caress their offspring, but also punish them for disobedience. Monkeys have excellent memory and are able to hold objects and use them as tools.

Humans and monkeys: main differences

Not all scientists agree that great apes are the ancestors of modern humans. on average is 1600 cubic centimeters, while this figure in animals is 600 cubic centimeters. cm. The area of the cerebral cortex also differs by approximately 3.5 times.

The list of differences related to appearance could take a long time. For example, representatives of the human race have a chin and turned out lips, allowing one to see the mucous membrane. They do not have prominent fangs, and their VID centers are more developed. Monkeys have a barrel-shaped chest, while humans have a flat chest. A person is also distinguished by an expanded pelvis and a strengthened sacrum. In animals, the length of the body exceeds the length of the lower limbs.

People have consciousness, they are able to generalize and abstract, use abstract and concrete thinking. Representatives of the human race are capable of creating tools and developing areas such as art and science. They have a linguistic form of communication.

Alternative theories

As already mentioned, not all people agree that monkeys are the ancestors of humans. Darwin's theory has many opponents who present more and more new arguments. There are alternative theories that explain the appearance of Homo sapiens on planet Earth. The oldest theory is creationism, which implies that man is a creation created by a supernatural being. The appearance of the creator depends on religious beliefs. For example, Christians believe that people appeared on the planet thanks to God.

Another popular theory is cosmic. It says that the human race is of extraterrestrial origin. This theory considers the existence of people as the result of an experiment conducted by cosmic intelligence. There is another version that says that the human race originated from alien creatures.

To date, there is no exact hypothesis about how and where they appeared. ancient human ancestors. Most scientists are of the opinion that humans and monkeys have a common ancestor. It is believed that somewhere 5-8 million years ago, the evolution of anthropoid apes went in two independent directions. Some of them remained to live in the animal world, and the rest, after millions of years, turned into people.

Rice. 1 - Human evolution

Dryopithecus

One of the ancient ancestors of man is Dryopithecus "tree monkey"(Fig. 2), who lived in Africa and Europe 25 million years ago. He led a herd lifestyle and was strikingly similar to a modern chimpanzee. Due to the fact that he constantly lived in trees, his forelimbs could turn in any direction, which played an important role in the further formation of man.

Features of Dryopithecus:

developed upper limbs contributed to the emergence of the ability to manipulate objects;
Coordination improved and color vision developed. There was a transition from a herd to a social way of life, as a result of which speech sounds began to develop;
brain size increased;
a thin layer of enamel on the teeth of Dryopithecus indicates the predominance of food of plant origin in its diet.

Rice. 2 - Dryopithecus - an early human ancestor

The remains of Australopithecus (Fig. 3) were discovered in Africa. Lived approximately 3-5.5 million years ago. He walked on his feet, but his arms were much longer than those of modern humans. The climate of Africa gradually changed and became drier, which resulted in a decrease in forests. More than half of the apes have adapted to new living conditions in open space. Due to the hot climate, ancient human ancestors, they mainly began to move on their feet, which saved them from overheating of the sun (the area of their back is much larger than the top of their head). As a result, this led to a decrease in sweating, thereby reducing water consumption.

Features of Australopithecus:

knew how to use primitive objects of labor: sticks, stones, and so on;
the brain was 3 times smaller than the brain of modern humans, but much larger than the brain of large monkeys of our time;
was distinguished by his short stature: 110-150 cm, and body weight could be from 20 to 50 kg;
ate plant and meat foods;
earned his own food using tools he made himself;
lifespan - 18-20 years.

Rice. 3 - Australopithecus

(Fig. 4) lived approximately 2-2.5 million years ago. The posture of his figure was very close to that of a human. He walked in an upright position, which is where he got his second name - “homo erectus.” Habitat Africa, as well as some places in Asia and Europe. In the Olduvai Gorge (East Africa), things made from partially processed pebbles were discovered next to the remains of Homo habilis. This suggests that the ancient ancestors of man of that time already knew how to create simple objects of labor and hunting, and select raw materials for their manufacture. Presumably a direct descendant of Australopithecus.

Features of a “skillful” person:

brain size - 600 cm²;
the facial part of the skull became smaller, giving way to the brain part;
the teeth are not very large, like those of Australopithecus;
was an omnivore;
the foot acquired an arch, which contributed to better walking on two limbs;
the hand has become more developed, thereby expanding its grasping abilities, and the grip strength has increased;
although the larynx was not yet able to reproduce speech, the part of the brain responsible for this was finally formed.

Rice. 4 - A “skillful” person

Homo erectus

Other name - Erectus(Fig. 5). Without a doubt he is considered a representative of the human race. Existed 1 million - 300 years ago. It got its name from the final transition to straight walking.

Features of Homo erectus:

possessed the ability to speak and think abstractly;
knew how to create quite complex objects of labor and handle fire. There is an assumption that an upright man could make fire on his own;
appearance resembles the features of modern people. However, there are significant differences: the walls of the skull are quite thick, the frontal bone is located lower and has massive supraorbital protrusions. The heavy lower jaw is larger, and the chin protuberance is almost invisible;
males were much larger than females;
height is about 150-180 cm, brain size has increased to 1100 cm³.

The lifestyle of the erect walking ancestor of man consisted of hunting and gathering edible plants, berries, and mushrooms. He lived in social groups, which contributed to the formation of speech. Perhaps it was supplanted by Neanderthals 300 thousand years ago, but this version does not have solid arguments.

Rice. 5 - Erectus

Pithecanthropus

Pithecanthropus - is rightfully considered one of ancient human ancestors. This is one of the varieties of upright man. Habitat: Southeast Asia, lived about 500-700 thousand years ago. The remains of the “ape-man” were first found on the island of Java. It is assumed that he is not a direct ancestor of modern humanity, most likely he can be considered our “cousin”.

Sinanthropus

Another species of Homo erectus. Existed 600-400 thousand years ago in the current territory of China. Sinanthropus are relatively developed ancient ancestors of humans.

A representative of the human race, he was previously considered a subspecies of Homo sapiens. Its habitat was Europe and North Africa more than 100 thousand years ago. The period of life of the Neanderthals fell just during the Ice Age; accordingly, in harsh climatic conditions, they had to take care of making clothes and building housing. The main food is meat. It does not relate to the direct relationship of Homo sapiens, but it could well have lived next to the Cro-Magnons, which contributed to their mutual crossing. Some scientists believe that there was a constant struggle between Neanderthals and Cro-Magnons, which led to the extinction of Neanderthals. It is assumed that both species hunted each other. Neanderthals (Fig. 6) had a massive, large physique, compared to Cro-Magnons.

Features of Neanderthals:

brain size - 1200-1600 cm³;
height - approximately 150 cm;
due to the large brain, the skull had an elongated backward shape. True, the frontal bone was low, the cheekbones were wide, and the jaw itself was large. The chin had a weakly defined character, and the brow ridge had an impressive protrusion.

Rice. 6 - Neanderthal

Neanderthals led a cultural life: musical instruments were discovered during excavations. Religion was also present, as indicated by special rituals at the funerals of their fellow tribesmen. There is evidence that these ancient human ancestors had medical knowledge. For example, they knew how to heal fractures.

Direct descendant of Homo sapiens. Existed approximately 40 thousand years ago.

Features of Cro-Magnons (Fig. 7):

had a more developed human appearance. Distinctive features: a fairly high straight forehead, absence of a brow ridge, a more distinctly shaped chin protuberance;
height - 180 cm, but body weight is much less than that of Neanderthals;
brain size was 1400-1900 cm³;
spoke clearly;
considered the founder of the first true human cell;
lived in groups of 100 people, so to speak, tribal communities, building the first villages;
engaged in the construction of huts and dugouts, using the skins of killed animals. He created clothing, household items and hunting tools;
knew agriculture;
he went hunting with a group of fellow tribesmen, chasing and driving the animal into a prepared trap. Over time, he learned to domesticate animals;
had its own highly developed culture, which has survived to this day in the form of rock paintings and clay sculptures;
performed rituals during the burial of relatives. It follows from this that the Cro-Magnons, like the Neanderthals, believed in another life after death;

Science officially believes that the Cro-Magnon man is a direct descendant of modern people.

The ancient ancestors of humans will be discussed in more detail in the following lectures.

Rice. 7 - Cro-Magnon

Saccorhytus coronarius

Paleontologists from China and Britain have discovered the fossil remains of one of the oldest known representatives of deuterostomes - a group of animals that includes all vertebrates. Saccorhytus coronarius lived about 540 million years ago, was about a millimeter in size, had a large mouth and no anus. published in the magazine Nature.

Deuterostomes are a large group of animals, which, in addition to vertebrates (and other chordates), also includes echinoderms, hemichordates, chaetognaths and several other groups. They are called deuterostomes because during embryonic development, an anus is formed in place of the primary mouth (blastopore), and the mouth independently develops at the anterior end of the body. Together with protostomes, in which the mouth is formed at the site of the blastopore (these include, for example, mollusks, arthropods and various groups of worms), they form a group of bilaterally symmetrical animals. Despite the large number of fossil deuterostomes found, not very many early representatives of this group are known, and therefore the initial stages of its evolution still remain a mystery.

The fossils were found in Early Cambrian strata in Southern China. In total, scientists discovered 45 samples. Their age is about 540 million years. The animal was about a millimeter in size and had a baggy, folded body. Scientists gave him a generic name Saccorhytus(from Greek words saccus- a bag, and rhytus- fold). The very large crown-like mouth gives the fossil its species name: coronarius. The fossil did not have an anus, but there were several (from one to four) conical holes on the sides of its body. It was through them, as scientists suggest, that the animal removed water and metabolic products from the body.

Saccorhytus coronarius in a scanning electron microscope

Several spines or bristles were found on the animal's body, which apparently played a protective role. Scientists also discovered two groups of round pores, which presumably could have a sensory function (but may simply represent entrance holes for additional unpreserved bristles). The animal's body, as the authors suggest, was covered with thin elastic skin and had muscles that allowed it to actively move. Saccorhytus coronarius, according to researchers, lived in the sand on the seabed and fed by swallowing water with food particles and, possibly, small organisms with its large mouth.

Saccorhytus is one of the oldest known representatives of deuterostomes and therefore can claim proximity to the most basal, ancestral lines of this group of animals. However, not all of its characteristics can be called ancestral: for example, the absence of an anus, according to scientists, is most likely secondary, because all other early representatives of deuterostomes had a through intestine.

Morphologically Saccorhytus closest to two extinct Cambrian groups: Vetulicolians and Vetulocystids. These marine animals, which, according to many scientists, were one of the earliest branches of chordates, had an elongated body with rows of gills on the sides. Based on this, the authors suggest that the conical holes on the body Saccorhytus may have later been transformed into gills.

Sofia Dolotovskaya