This mystery haunted paleontologists for 150 years. Something called Prototaxites could not be confidently assigned not only to a family or genus, but to any biological kingdom. Only in our days has the analysis of fossils made it possible, it seems, to decide on this gigantic creation of the ancient Earth, which, however, has not ceased to be extremely surprising.

The history of Prototaxites is a great example of what to see and understand - what do you see, as they say, two big differences. The American scientist J.W. Dawson, who first described this mysterious creature (in 1859), believed that these were fossils of rotten wood, somehow connected with the current yews (Taxus), therefore he gave them the name Prototaxites. Only now, before real yews, this creature had to "stomp and stomp", because Prototaxites was distributed, though throughout the Earth, but only 420-350 million years ago.

At the end of the nineteenth century, scientists began to think that it was a seaweed, more precisely, a brown seaweed, and this opinion was strengthened, getting into encyclopedias and textbooks for a long time. Although it is difficult to imagine something similar to an algae (or a colony of algae?), which has grown in the form of a "trunk" of six, and sometimes nine meters in height, is difficult.

By the way, Prototaxites was the largest organism on land at that time: vertebrates had just begun to appear, so wingless insects, centipedes, and worms crawled around the strange high "pillar".

The very first vascular plants, the distant ancestors of conifers and ferns, although they appeared 40 million years earlier, nevertheless, at the moment when Prototaxites settled on Earth (in the early Devonian), they did not yet rise above a meter.

By the way, about the size. In Saudi Arabia, a 5.3 meter long specimen of Prototaxites was found, which has a diameter of 1.37 meters at the base and 1.02 meters at the other end. In the state of New York, they dug up a trunk 8.83 meters long with a diameter of 34 centimeters at one end and 21 centimeters at the other. Dawson himself described a specimen from Canada - 2.13 meters long and with a maximum diameter of 91 centimeters.

What else is important to note regarding the structure of Prototaxites. It doesn't have cells like plants have. But there are very thin capillaries (tubes) with a diameter of 2 to 50 micrometers.

Nowadays, scientists, based on the results of many years of research on this representative of the ancient living world, have put forward new versions. Some experts, starting with Francis Hueber of the American National Museum of Natural History (Smithsonian Institution, National Museum of Natural History), are inclined to believe that Prototaxites is the fruiting body of a huge fungus; others - to the fact that it is a huge lichen. The latest version, with his own arguments, was put forward by Marc-Andre Selosse from the University of Montpellier (Universite de Montpellier II).

One of the ardent proponents of the mushroom version is Charles Kevin Boyce, now at the University of Chicago. He published several works devoted to the detailed study of Prototaxites

Boyce never ceases to be amazed by this creature. “No matter what arguments you put forward, something crazy still comes out,” says the researcher. “A mushroom 20 feet tall does not make any sense. No seaweed will give 20 feet tall. us".

Recently, Francis Huber completed a titanic job: he collected many specimens of Prototaxites from different countries and made hundreds of the thinnest sections, making thousands of photographs of them. Analysis of the internal structure showed that it is a mushroom. However, the scientist was disappointed that he could not find characteristic reproductive structures that would clearly indicate to everyone that, they say, this is really a mushroom (which gave confidence to Huber's opponents from the "lichen camp").

The latest (in time, but clearly not the last in the history of Prototaxites) proof of the fungal nature of the strange organism of the Devonian period is an article by Hueber, Beuys and their colleagues in the journal Geology.

"The large range of isotopes found is difficult to reconcile with autotrophic metabolism, but it is consistent with anatomy indicating a fungus and with the assumption that Prototaxites was a heterotrophic organism that lived on a substrate rich in various isotopes," the authors of the article write.

Simply put, plants get their carbon from the air (from carbon dioxide), while fungi get their carbon from the soil. And if all plants of the same species and of the same era show the same isotope ratio, in mushrooms it will depend on the place where they grow, that is, on the diet.

By the way, the analysis of the ratio of carbon isotopes in different specimens of Prototaxites is now helping scientists to recreate the native ecosystems of this ancient creature. Since some of its specimens seem to have "ate" plants, others used the microbial community of the soil as food, and still others may have received nutrients from mosses.

Carol Hotton, co-author of this study, Carol Hotton, of the Smithsonian Museum of Natural History, discusses the mystery of the large growth of the Paleozoic fungus: she believes that the large size helped the fungus spread its spores further - through scattered swamps, randomly scattered across the landscape.

Well, when asked how this mushroom grew to such a monstrous size, scientists simply answer: "Slowly." After all, there was no one to eat this mushroom at that time.

But what to do? Sections of fossils stubbornly "did not want" to resemble sections of trees, and in general - they did not look like a plant. Rings on sections, by the way, are observed there, but these are not annual rings of trees.

Herbivorous, armored ankylosaurs are famous for their massive "club" at the end of the tail, which apparently served as a defensive weapon. But experts also know their other intriguing feature: the vast majority of the discovered remains of these dinosaurs were buried with their belly up.

Discussions on this topic began as early as the 1930s, and so far there have been a lot of hypotheses, the most important of which have recently been tested by a group of paleontologists led by Jordan Mallon of the Canadian Museum of Natural History. But first, they made sure that the “ankylosaur orientation problem” is not a historical myth. Scientists reviewed 36 finds made in Canada and the reports of their authors, confirming that 26 of them were indeed upside down. It cannot be explained by chance.

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The authors then began testing the key theories that explain this phenomenon. The first of them suggests that the ankylosaurs were rather clumsy in their movements and, having fallen on their backs, could not roll back, and the predators knocked them over on their backs, reaching the belly, which was not protected by shell plates. Scientists did not find any evidence for this, and teeth marks were found only on one of the studied samples. “If the ankylosaurs were so sluggish, they would hardly have survived for about 100 million years,” adds Jordan Mallon.

Another hypothesis believes that everything is connected with the shape of the armored body of ankylosaurs and with the location of their center of gravity. When an animal died and was decomposed by bacteria, its belly would have to swell, which could naturally turn it upside down. In favor of this hypothesis, it is usually indicated that this happens with modern armadillos. However, when Mallon's colleagues themselves examined 174 bodies of animals hit by cars, there was no confirmation of this. The authors also followed the decomposition of some dead armadillos, while not one of them "naturally" turned over on his back.

Another model explains the orientation of the remains by the fact that the bodies of dead animals could be in the reservoir, afloat, and easily turned over under their own weight. Subsequently, they found themselves at the bottom or aground and were brought in by sedimentary rocks already in such an inverted position. To test this version, Mallon and his co-authors developed three-dimensional computer models of the buoyancy of the bodies of the two main varieties of ankylosaurs (ankylosaurids and nodosaurids), taking into account their bone density, lung volume, etc.

By placing the models in a virtual river and "inflating" their bellies - as if by the action of gases that continue to release intestinal bacteria after death - the scientists monitored their behavior. In the case of the dinosaur, the hypothesis worked: even a small random deviation was enough for the body to turn upside down afloat. Ankylosaurids proved to be more stable, but with a strong enough wave, and they switched to a more stable inverted orientation. This, apparently, happened once in nature, leaving paleontologists one of the many, and now solved, mysteries of dinosaurs.

After again analyzing the data on the structure of the mysterious extinct animal, scientists decided that it could not

Strange fossils discovered in the middle of the twentieth century. in the US state of Illinois, became the beginning of one of the most interesting mysteries of paleontology. In honor of Frey, who found the first sample

After again analyzing the data on the structure of the mysterious extinct animal, scientists decided that it could not be a fish, as was thought until recently. The riddle of the tullimonster remains open.

Strange fossils discovered in the middle of the twentieth century. in the US state of Illinois, became the beginning of one of the most interesting mysteries of paleontology. In honor of Francis Tully, who found the first specimen, these creatures were named "tullimonsters", today there are several hundred of them. The remains are dated at about 310 million years old - at that time, a river delta rich in life was located in this territory. At the same time, it is not possible to strictly classify these animals.

The imprints of soft-bodied tullimonsters are too vague and indefinite, so paleontologists put forward a variety of versions about their structure and appearance, sometimes attributing them to mollusks, then to arthropods. In 2016, Victoria McCoy and her co-authors described them as related to lampreys: "Tullimonster is a vertebrate," was the title of an article they published in Nature. "Tullimonster is an invertebrate," argues a new paper in the journal Paleontology.

Tullymonster can be anyone / Lauren Sallan

The authors of last year's article, having studied more than a thousand remains of tullimonsters, noted a light stripe running along the middle of the body, like a notochord, a primitive spine. Some other details reminded scientists of gill sacs and teeth, also characteristic of vertebrates - more specifically, jawless fish, relatives of modern hagfish and lampreys.

The authors of the new article dispute these interpretations. Lauren Sallan of the University of Pennsylvania and her colleagues note that the position of the elements that were mistaken for gill sacs shows that they could hardly have been involved in respiration. Does not agree with the structure of the vertebrate and the location of the part, which was identified as a liver. In their work, Sallan and her co-authors turned to the anatomy of the tullimonster's eyes.

Tullimonster Interpretation: Vertebrate / Nobu Tamura

They already had a rather complex structure and contained melanosomes - cells that accumulate melanin pigment. However, the shape of the tullimonster's eyes was still the most primitive, cup-shaped, devoid of a lens-crystal. “The problem is that if they have cupped eyes, then they cannot be vertebrates,” says Lauren Sallan, “because all vertebrates have more complex eyes, or have simplified it a second time. At the same time, many other creatures have such eyes - primitive chordates, molluscs and some worms.

There were no analogues of some other structures found in marine vertebrates in tullimonsters - traces of an auditory capsule, which serves animals to maintain balance, and a lateral line, a sensory organ. “One would expect that at least some of the remains of them will be preserved,” Sallan emphasizes. “It turns out that these creatures have something that vertebrates should not have, but they don’t have something that surely should have been and preserved.”

A tullimonster print at the Natural History Museum in Milan / Wikimedia Commons

Thus, the authors again analyze the old data and make the assumption that the tullimonster still belonged to some group of invertebrates. At the same time, no new research has been carried out, and many experts note that the secret remains a secret - neither a mollusk, nor a worm, nor an arthropod strange creature is also completely unlike.

The dramatic increase in biodiversity that occurred during the Cambrian period was prepared for a long time by molecular evolution, which eventually led to the Cambrian explosion of species diversity.

Trilobite is one of the ancient arthropods, whose appearance fell on the Cambrian period (photo by mattheaton).

In biology, there is a well-known paradox of the Cambrian explosion. Its essence is that from some point life on earth begins to demonstrate an enormous variety of forms, traces of which can be found in prehistoric fossils. This moment happened in the Cambrian period - but before that, no signs of future life forms could be found. Revolutionary leaps in nature are relatively rare, and if we talk about a planetary scale, they are completely incredible. Meanwhile, one gets the feeling that the organisms acquired at once, as if at a mass sale, an incredible number of new features and began to quickly disperse into systematic groups.

Of course, one can assume divine intervention or that some aliens have shaken out a bag of new species onto Earth. Scientists, however, did not stop trying to find at least some scientific explanation for the paleontological mystery. Charles Darwin thought about the problem of the sudden "emergence" of new fossil species - and came to the conclusion that in such cases, archaeologists and paleontologists need to "dig better" in every sense.

A group of evolutionary biologists from several American universities published an article in the journal Science, which presents the results of another rethinking of the mystery of the Cambrian explosion. Scientists have revised the relationship between the remains of ancient creatures, taking into account the latest finds, as well as the archaeological age of these finds. The genealogical relationships of fossil species with their modern descendants were clarified. In addition, data from molecular genetics were used: the researchers reconstructed the genealogy of several genes found in 118 modern species. All together, it made it possible to clarify the branching points on the family tree and determine exactly when a particular group began its own evolutionary path.

In general, the conclusions of the researchers boil down to the fact that the Cambrian revolution was preceded by a long invisible evolution. Over millions of years, organisms accumulated genetic and biochemical changes that in the Cambrian led to the emergence of different forms of life: the accumulated internal changes finally resulted in external changes. The authors compare this to the industrial revolution: inventions, small technological innovations accumulated for a long time without much change in the means of production, until finally they led to a global technological shift.

Accumulated genetic changes have been balanced for some time by the external environment and relationships between species. And from a biochemical point of view, different organisms already before the Cambrian could differ significantly from each other, demonstrating great biodiversity. Subsequently, the slightest ecological shifts should have been enough to allow the accumulated changes to manifest themselves from the outside. By the way, one of the very bold, albeit rather controversial hypotheses put forward in the article is the assertion that Precambrian animals ate each other more intensively: this may be one of the reasons for the scarcity of Precambrian fossil remains.

This is not to say that the new hypothesis has not attracted the attention of critics. Thus, one of the claims against the authors is that they did not take into account the so-called orphan genes, which make up approximately 30% of all animal genes. These genes have no homologue "relatives", and many believe that it was their sudden appearance that could have caused the Cambrian explosion of biodiversity. However, in this hypothesis, alas, there is the word "suddenly", from which science always tries to get rid of by all means.