Most paleontologists no hope that ever in the fossil record they will be able to find the remains of the nervous system. It is believed that neurons are too vulnerable and decompose long before fossilization begins.
However, in recent years there have been several research works in which they talked about the traces of nerve tissue in fossils belonging to Cambrian period.
So, in 2013, a group of paleontologists, working under the direction of Nicholas Strausfeld (Nicholas Strausfeld) from the University of Arizona, published a description of amazing finds. Found in China the fossil arthropod of the genus allgomera (Alalcomenaeus), the researchers found something I thought was the remnants of nervous tissue.
not all experts agreed with this interpretation of the data. Skeptics noted that such traces could be formed by natural processes, not related to the anatomy of the animal.
In 2014, the team of Strausfeld described another fossil with traces of a nervous system, but researchers again failed to convince critics.
In 2016, another group, headed by Javier Ortega-Hernandez (Javier Ortega-Hernndez) of Harvard University has published information about a new discovery. But many experts are not recognized as sufficiently persuasive.
the reconstruction of the anatomy of an ancient arthropod.Illustration Ortega-Hernandez et al. 2019.
the Crucial opening?
Now published the evidence which may be decisive. Ortega-hernández and his colleagues described in the new work from two findings.
the material of the publication Live Science, Strausfeld calls the new work groups, Ortega-Hernandez (in which the commentator did not participate) a nice proof of the results of the earlier studies. The article allows you to remove the many objections raised against previous publications, the researcher notes.
the Speech again goes about the Cambrian animals of the genus allgomera. One of the samples were recently found by the authors in the United States. The other comes from the same area, but was discovered in 1990-e years.
Paleontologists have discovered the first fossils of the spots, the shape and arrangement very reminiscent of the remnants of the Central nervous system. The experts saw neural circuit that runs along the whole body, individual paired nerves and ganglia.
it is Particularly important that these lines were symmetrical and drove straight to the places where ancient animal was probably located his four eyes. It is noted that the nervous system of a prehistoric animal similar to its counterpart in modern spiders, Scorpions and some other animals.
Chemical analysis showed that the composition of these discolorations much carbon. It fits perfectly with the hypothesis that we are talking about the balance of the nervous tissue, which is known to be particularly rich in lipids.
the Second investigated sample showed almost the same pattern. The authors note that the nervous system of both instances is very similar to that found in the genus allgomera found in China.
Also interestingly, all three samples are similar in conditions in which there was calcification. Scientists believe that the preservation of nervous tissue is made possible thanks to the specific factors. Those could be, for example, the combination of a suitable level of humidity a certain kind of clay, which launched a process similar to the tanning of the skin.
a Comparison of the specimen found in the 1990-ies (left) and recently discovered (on the right).Photo of Ortega-Hernandez et al. 2019.
do you still have
the New work was presented on court of experts recently, and her road to recognition is not going to be easy. The fact that alternative scenarios of the occurrence of suchtion traces are still not excluded.
So, in 2018, the group headed Czarny Liu (Liu Jianni) from northwestern University in China published an interesting study. It was about how the Cambrian fossils may have spots that are easily mistaken for traces of internal organs.
Examining about 800 fossils, the experts found that about 10% of them contain the darkening in the head. After analyzing their possible nature, paleontologists have concluded that the reason may be biofilm of a bacteria, and not the remains of internal organs.
Some of these spots purely by chance can materialize, similar to the structure of the nervous system, say the skeptics.
“We appreciate the efforts of the authors to substantiate their results as a genuine discovery of the nervous tissue, but are skeptical of the data obtained only from two fossils – expresses his position Liu. – New data are always welcome, but as we said earlier, we would be more convinced if the anatomical features appearing in the agreed form on multiple samples independently from each other.”
the Skepticism scientists can understand. Fossils, especially such ancient, it is difficult to interpret. So, before “Conduct.Science” (nauka.vesti.ru) wrote about the fossil, the nature of which was revised several times. Recently, we also told about who really was the “giant spider” the time of the dinosaurs.