This mystery haunted paleontologists for 150 years. Something called Prototaxites could not be confidently attributed not only to a family or genus, but to any biological kingdom. Only in our days, the analysis of fossils has made it possible, it seems, to determine the same with this giant creation of the ancient Earth, which, however, has not ceased to be extremely amazing
The history of Prototaxites is a great example of what to see and understand - what you see, as they say, are two big differences. The American scientist JW Dawson, who first described this mysterious creature (in 1859), believed that these are fossils of rotten wood, somehow related to the current yews (Taxus), and therefore gave them the name Prototaxites. Only before the real yews this creature was “stomping and stomping”, because Prototaxites was widespread, though all over 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, or rather, a brown seaweed, and this opinion was strengthened, for a long time getting into encyclopedias and textbooks. Although it is difficult to imagine something like an algae (or a colony of algae?), Which has grown in the form of a "trunk" of six or sometimes nine meters in height.
But what to do? The fossil cuts stubbornly "did not want" to resemble tree cuts, and indeed they did not look like a plant. Rings on sections, by the way, are observed there, but these are not annual rings of trees.
By the way, Prototaxites was the largest organism on land at that time: vertebrates were just beginning to appear, so that wingless insects, centipedes, and worms crawled around the strange high "pillar".
The very first vascular plants, the distant ancestors of conifers and ferns, even though they appeared 40 million years earlier, nevertheless, at the time when Prototaxites settled on Earth (in the early Devonian), they still did not rise above a meter.
By the way, about the size. In Saudi Arabia, a 5.3 meter long sample of Prototaxites has been found that has a diameter of 1.37 meters at the base and 1.02 meters at the other end. In New York State, 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 a maximum diameter of 91 centimeters.
It is also important to note about the structure of the Prototaxites. It doesn't have the kind of cells that plants do. But there are very thin capillaries (tubes) with a diameter of 2 to 50 micrometers.
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Nowadays, scientists, based on the results of many years of research of this representative of the ancient living world, have put forward new versions. Some experts, beginning with Francis Hueber of the American National Museum of Natural History (Smithsonian Institution, National Museum of Natural History), have tended to believe that Prototaxites is the fruiting body of a huge mushroom; others mean that it is a huge lichen. The last version, with his arguments, was put forward by Marc-André Selosse of the University of Montpellier (Université de Montpellier II).
One of the ardent supporters 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 (here, for example, a short description of one of them).
Boyce never ceases to be amazed at this creature. “No matter what arguments you put forward, it still turns out to be something crazy,” says the researcher. “A mushroom 20 feet tall makes no sense. No seaweed will give you 20 feet of height. But here it is - the fossil - in front of us."
Recently, Francis Huber completed a titanic work: he collected many copies of Prototaxites from different countries and made hundreds of the finest cuts, having completed thousands of their photographs. An 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, it really is a mushroom (which gave confidence to Huber's opponents from the "camp of lichens").
The last (in time, but certainly not the last in the history of Prototaxites) evidence of the fungal essence of a strange organism of the Devonian period is an article by Huber, Beuys and their colleagues in the journal Geology.
The authors of the new work analyzed the ratio of carbon isotopes in super mushroom fossils and plant fossils from the same period. The difference clearly indicated that Prototaxites were not a plant.
"The large spectrum of isotopes found is difficult to reconcile with autotrophic metabolism, but it is consistent with the anatomy that indicates a fungus, and with the assumption that Prototaxites was a heterotrophic organism that lived on a substrate rich in various isotopes," the authors write.
Simply put, plants get their carbon from the air (from carbon dioxide), and 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, on the diet, that is.
By the way, the analysis of the ratio of carbon isotopes in different copies of Prototaxites is now helping scientists to recreate the native ecosystems of this ancient creature. Since some of its specimens, it seems, "ate" plants, others used the soil microbial community as food, and still others, perhaps, received nutrients from mosses.
The 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 mushroom spread its spores further - through scattered marshes, chaotically 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.