We know them in death. We know how they died, what they ate, how they grew up, where they wandered, and even when they were sick or injured. The surviving bones can tell us a lot, but perhaps the most interesting are the stories they left behind, as their behavior was recorded even for a moment. Fossil tracks - things like preserved footprints, feces and nests - provide a close look at creatures that no longer lived on the planet, showing that ancient life could be majestic, wild and sophisticated, but it also had its misfortunes and their justice. . to be as strange and disgusting as life is today.
Clumsy Giants
Take sauropods. Their sheer size creates images of grandeur that are reinforced by the museum displays of these huge, long-necked dinosaurs and their subsequent depictions in films. But there must have been times when these creatures were not so majestic.
To learn more
This is exactly what Arturo Heredia, Pablo Passas and Diana Elizabeth Fernandez describe in a recent article in Publications of the Heological Society of London. There is evidence that a young group of sauropods slithered along a tidal channel 130 million years ago.
Their traces were left on the Rayusu hill in the province of Neuquen. This is just part of a rich Lower Cretaceous formation in Argentina known as the Agrio Formation, which is full of amazing and well-preserved archaeological fossils. On Raiosa Hill, the details of this tidal flat ecosystem are amazing, including water level markers, a large group of preserved sediment waves from an ancient tide, and an ancient horseshoe crab (xyphosurid) mating site. Based on the size and shape of the footprints, the team determined that they were young sauropods of varying ages walking and gliding parallel to the tidal channel.
What those consequences actually were was not immediately clear. The team ruled out signs of eating large marine reptiles such as plesiosaurs or ichthyosaurs. Feeding lanes will be deeper at one end, which is not visible on these lanes. Also, the amount of water available in the last set of footprints makes it unlikely that an aquatic organism (fish or marine reptile) could have done it. They are also not indicative of a lethargic or predatory fish for a number of reasons: the morphology is inconsistent, there is no evidence of sediment digging as seen in predators, and most fish are not heavy enough to make such marks. Alternatively, they may be theropods or sauropods. However, theropods were easily discarded because the footprints were not three-toed like those of theropods. Among them, crescent-shaped footprints, which are a hallmark of sauropods, were found, and this was the biggest piece of evidence.
After analyzing some of the sediment in the footprints using a scanning electron microscope, they determined that the slippery microbial mat was responsible for the loss of legs in this group of young sauropods. These layered covers of microorganisms such as cyanobacteria still exist today. Not only did this cause these dinosaurs to slip, but this microbial mat, as well as the area surrounding this tidal wave, may have helped preserve their footprints. but how?
Arturo Heredia is the lead author of this article and a CONICET Fellow at the Andinos Institute Don Pablo Grober (IDEAN). Consider, as Heredia explains in a video interview, the different ways to keep or not to keep your footprints while walking on the beach. Get close to the water and you can be swallowed up by the energy of the waves or tides. Neither too deep in the wind-dried sand, nor loose grains of sand can keep the shape of the trail. But if you get close enough to the water, where the sand is neither too dry nor too wet, the trail will hold its shape. This also applies to ancient monuments. “Water retention in the nozzle is important to maintain the shape of the trail,” he explained.
Humidity is also important for the growth of microbial mats. Some cyanobacteria have filaments that "catch sediment like a net," he said, so when something like a sauropod walks and glides across this microbial mat, those tracks maintain their elongated shape thanks to the grains attached to them. carpet. This gives them "enough time to deposit and continue to petrify," he added.
Microbial mats certainly help preserve trace fossils, but according to co-author Diana Elizabeth Fernandez, a CONICET researcher also at IDEAN (CONICET-UBA), more archaeological fossils would have been preserved without them. The past two decades have improved our understanding of microbial mats associated with archaeological sites, she said in a video interview, including the fact that microbial mats are “more common than we thought.” In particular, she added, microbial mats “contribute to the quality of preservation. And in this case, of course, they were necessary in order for this surface itself to remain slippery.
Pablo Passas, her former supervisor and PhD co-author, first saw the tracks about 10 years ago while studying horseshoe crab tracks nearby. “He has a very sharp eye,” she said. “In addition to his work in the field of ichthyology, he is a sedimentologist, so his education is related to geology. He is very good at detail. We were lucky enough to work on this when the sun hit the surface at a certain angle. sticking out. Everything is softened." We didn't know what it was, but we knew it was some kind of stupidity!
Cut out the predator?
Stupidity is certainly not characteristic of sauropods, and possible evidence of this has been found off the coast of Yorkshire, UK. Millions of years before the appearance of a young group of sauropods, a giant theropod - a carnivorous bipedal dinosaur - left a large and unique footprint. It has three toe prints and theropod claws, but the heel goes far back, which is not the case with other similar prints. The authors of an article published in the journal Proceedings of the Yorkshire Geological Society offer three possible explanations: 1. This dinosaur may have been crouching or lying on the ground, 2. This could have been the dinosaur's footprint as it slid forward from a crouched position, or 3. This could mean that he slipped. It is difficult to definitively identify anything from a single fingerprint.
But even this fossilized footprint provides fascinating information about the animal that left it. Leather casts survive, suggesting that the feet were stuffed, and the size of the cast gives an estimate of the height of the hips: a staggering 2.5-3 meters (about 8-10 feet).
“It should have weighed between 1.5 and 2 tons,” lead author and geologist John Hudson explained via email. This points to the carnivorous Megalosaurus as a possible artist, a dinosaur that lived in England during the mid-Jurassic period around 165-175 million years ago. This animal could be from 6 to 8 meters in length.
“At the time, it would have been the most dangerous predator,” Hudson said.
Like the sauropod tracks, this track was found in a relatively humid environment, in an area where "there was never a major river system, but there were several meandering arms with floodplains, floodplains and crevices," Hudson explained. Fossil pollen and spores indicate that a number of coniferous trees and plants grew in the area. The details of this ecosystem, which Hudson says "exists nowhere else in the world today," provide an intriguing insight into the ancient world.
“Sometimes when we study the fossils of the bodies of extinct animals, we can never be sure that they were in their original place,” Hudson said. “When fossils are found, they are often preserved where the animal walked. Therefore, when we explore a site, all potential sources of evidence, fossilized bodies, fossils, and any environmental evidence, such as local flora, are considered to give us a better idea. site photo than it was.
Skin wrinkles
Although there are no beetles in the footprints found in the Boskavice River basin in the Czech Republic, it is especially noteworthy that they also left marks on the skin. They also provide evidence for the existence of species that did not previously leave fossils in the area. These are the fossilized remains of animals that lived during the early Permian period, approximately 293 to 299 million years ago. In other words, paleontologists now know that these four-legged (or quadrupedal) creatures were in the area, and have an idea of what the skin on the soles of their feet looked like at an incredibly difficult time distance to understand. . .
In an article published in the journal Scientific Reports, the team describes three sets of footprints, including one from a different location in the Czech Republic. It is notoriously difficult to match fossilized footprints with the species that left them, so ichthyologists—those who study fossil ichnofossils, which is another word for footprint—will refer to the footprint itself in terms of shape and size. “Every biologist is trying to identify the closest possible trace,” Gabriela Kalapkova, lead author and paleontologist at the Moravian Museum, wrote in an email to Gizmodo. “Unfortunately, it is often not possible to identify a particular indicator at the species or genus level, not only because it is often not preserved in the fossil record, but also because different species can leave identical traces.”
The team narrowed it down to early divergent synapsids—like the ancestors of mammals—and found that the tracks belonged to species with a body length of 13 to 15 inches. According to Kalapkova, this does not include the tail, head and neck. And while it may seem small compared to theropods and sauropods, it "was not very small for its time," she said.
These synapsids "had an elongated posture. They were not sprinters," she said. "Upright posture, which allowed them to move more efficiently and quickly on land, appeared only in their descendants of pythons."
According to Kalabkova, these and other recently explored pathways are important because they "completely changed our current understanding of the diversity of terrestrial tetrapods in early Permian Bohemia."
She continued: “It all started in 2018 when fossil explorer and my good friend Thomas Wiktorin brought me the footprints of a small reptile he had just found in the Boscovich Basin.” Since I suspected that a hitherto unknown fauna from the Puskavichskaya hollow had left it. Since then my colleague Dr. Jakob Brezina of the Moravian Museum, paleontologist Thomas Wiktorin and I have done a lot of field work, finding traces not only of synapses, but also of early reptiles, large Seimuriamorphs, diadectomorphs (the first herbivorous tetrapods), and large temnospondyls. It is amazing to be able to turn hours of hard work in a muddy and inaccessible area into a discovery that will bring something completely new to our field, such as the first handprint that Anya carved on the arms and legs of early divergent synapsids.
Yuk is a bad snack
Archaeological fossils are not only formed in humid environments; This can also happen in the water itself. Articles published in 2010 and 2015 offer a startling glimpse of sea creatures that may have just been looking for food, but are looking for something less attractive instead.
Evidence found in three types of coprolites, or fossilized feces, shows that ancient sharks and ancient gorse — a type of long-snouted fish — bit them and then released them. As the authors point out, the presence of coprolites indicates that they were not eaten, but why did the animals bite them?
The team suggests that the sharks may have eaten it to determine if the sharks were potential food and immediately spit it out again. This test of bite behavior is known today in sharks. But another possibility is interesting: could the coprolites have been part of the victim's entrails when the shark attacked her? In this case, a bite mark may remain as the coprolite exits the body from the open wound and falls to the seabed, where it is eventually covered and deposited by sediment. These coprolites were found near the Miocene rocks from about 5 to 23 million years ago.
It was not possible to date caprolite with a bone bite, as it was found in deposits of the Mixed Period. Modern humans are notorious for stalking their prey. Using modeling clay, the team reproduced the types of marks on this coprolite with existing human teeth. If earlier the girls also lay in wait for the planned meal, they probably caught the prey and missed it, or accidentally grabbed the feces. Like a caprolite bitten by sharks, it was not eaten.
The lead author on both articles is Stephen Godfrey, curator of paleontology at the Calvert Maritime Museum. These fossils are examples of "extremely rare" compound fossils: fossils within fossils (in this case, coprolites with bite marks).
He said: "To me, the most exciting aspect of all this is the sheer improbability that this type of composite fossil footprint could be formed and preserved." This shows that evidence of very unlikely events can be preserved in the fossil record, to what extent can it be preserved...? "
The social life of fish
Not all watermarks are potentially repulsive. Argentine scientists have discovered strange fish tracks from the Paleozoic era, from about 419 to 443 million years ago. The traces of these excavations are described in an article published in Palaios. As mentioned earlier, ichthyologists give names to fossil tracks themselves, as the exact creator of the tracks is often unknown. This team named the new ichnofossil Raederichnus dondasi : tear-shaped perching marks made by fish that are the earliest and earliest evidence of fish gregarious or gregarious behavior. The name is derived from "raedera", the name of a stone tool made by local Pampas hunter-gatherers during the Paleolithic era in South America; "ichnos" or Greek trail; and "dondasi" Alejandro Dondas, a field engineer and self-taught paleontologist.
Raederichnus dondasi appears to be the footprints of a jawless fish resting in the shallow waters of the intertidal zone. The team narrowed down the fish's potential breeding or feeding behavior. Cloning seemed unlikely given the environment in which these footprints were found and the distance between the fossils. And while ancient tails are known to have existed in the Paleozoic, they also leave very distinct marks, none of which resemble Raederichnus dondasi.
Lead author Karen Halpern is a paleontologist at the National University of Mar del Plata.
“I had a lot of doubts when I first saw these fossils,” she wrote to Gizmodo, explaining that it took a lot of observation and thinking to figure out what these archaeological fossils might be. “My colleagues helped me in many different ways, discussing and arguing about many other options. When we finally ruled out that horseshoe crabs are unlikely to be their descendants, we added ichthyologist Soledad Guerike Kavali to the team. She was very happy about it! "
Halpern noted that “most fish nest in calmer environments,” especially those that do not allow predators to enter, such as “estuaries where the salinity is so low that no other marine predators (such as arthropods or squid) can survive.” ". ".
Another important clue was the divergence of these tracks from each other. This feeding behavior prevents competition.
She added: “I hope that similar discoveries can be made in other places!” "And if more evidence comes up in the near future and our interpretation is wrong, I hope someone takes the time to write and publish this!" It works!
Old death march
The vast majority of the tracks required serious detective work to figure out what the fossils might have left behind. But there are interesting and surprising excavations where the tracer is located, for example, from the inside (like in a pit) or at the end (like in a corridor). After millions upon millions of years of fish leaving footprints in shallow water, the ancient horseshoe crab (limulid) not only left its distinctive footprints as it walked on the seabed, but also died and was perfectly preserved at the end of those footprints.
This amazing 9.7 meter long fossil was originally found in the Solnhofen limestone formations in Bavaria, Germany and later settled at the Wyoming Dinosaur Center in the USA.
At only 5 inches tall, this arthropod would be young. And while there's no way to know for sure, researchers believe this tiny horseshoe crab may have been tossed into the poisonous lake by a massive storm. Available evidence suggests that this was an oxygen-poor area characterized by high salinity, a lethal combination for most organisms. Хотя другие хорошо сохранившиеся некроморфы — так называются окаменелые следы, которые документируют марш смерти организма — в известняке, который также был найден недалеко от Зольнхофена в Баварии, ничто не нарушало фон. Он был почти полностью мертв.
Особая Мортичния рассказывает очень грустную, но захватывающую историю. Шаг за шагом подкова идет, меняет направление, ползет вперед и, наконец, умирает от удушья. Каманда адзначае, што сярод іншых выкапняў са слаёў Solnhofen, якія дэманструюць падобныя маршы смерці, падковавы выжылі даўжэй, чым большасць іншых відаў. Ракападобныя і мідыі гінулі ў межах некалькіх дэцыметраў і сантыметраў. Каманда інтэрпрэтавала некаторыя з нерэгулярных слядоў як доказ таго, што краб-падкова быў дэзарыентаваны і ў бядзе.
Дын Ломакс, сааўтар вышэйзгаданага артыкула Theropod Tracks, палеантолаг, навуковы камунікатар і аўтар, з'яўляецца вядучым навукоўцам артыкула 2012 года, апублікаванага ў Ichnos.
"Гэта адно з самых дзіўных выкапняў, якія я калі-небудзь бачыў", - напісаў ён у электронным лісце. «Я выявіў гэтую дзіўную выкапень у свой першы дзень у якасці валанцёра ў Ваёмінгскім цэнтры дыназаўраў у 2008 годзе, калі мне было 18 гадоў».
Ён апісаў, як заплаціў за дарогу з Донкастэра, Англія, у Ваёмінг, прадаючы сваю маёмасць. Нават, як ён кажа, «дарагая калекцыя Star Wars». Ён працаваў там валанцёрам на працягу чатырох месяцаў і вярнуўся праз гады, каб вывучыць гэтага маленькага краба-падкова.
«Аднак пры вывучэнні гэтага выдатнага выкапня нельга не адчуваць смутку па маладым Лемулідзе, які загінуў у такіх трагічных абставінах. Але пасля смерці гэты старажытны членістаногі ператвараецца ў незвычайную гісторыю, удыхаючы новае жыццё». Ён удыхае ў вывучэнне выкапняў ".
Ён працягнуў: «Выкапні зрабілі незабыўнае ўражанне, натхніўшы мяне напісаць кнігу, прысвечаную незвычайным выкапням з доказамі іх паводзін, што ў выніку прывяло да стварэння фільма «Заблакіраваныя ў часе: паводзіны жывёл у 50 выяўленых незвычайных выкапнях ».
У яго цудоўнай кнізе змяшчаецца дадатковая інфармацыя аб гэтай Mortichnia, а таксама аб многіх іншых масіўных целах і слядах выкапняў з розных геалагічных перыядаў.
Кожнае з гэтых адкрыццяў узбагачае наша разуменне мінулага жыцця на гэтай зямлі. Многія з апісаных вышэй істот не маюць сучасных аналагаў; Яго ажыўляюць даследаванні, музеі, кнігі і наша ўяўленне ў палеамастацтве і CGI. Некаторыя з іх сыходзяць так далёка ў мінулае і настолькі невядомыя шырокай публіцы, што гэта цяжка ўявіць. Але гэтыя паводзіны не з'яўляюцца. Пазнейшая група маленькіх, слізгаючых зауроподов, жахлівага выгляду тэрапод, які губляе апору: гэта дзеянні, з якімі мы можам ідэнтыфікаваць сябе. Чым больш слядоў выкапняў будзе знойдзена і інтэрпрэтавана, чым больш частак галаваломкі мы збярэм, тым больш пазнавальнымі становяцца вымерлыя істоты.
ذكر جودفري أنه "لن نصل أبدًا إلى نهاية القصص التي يمكن أن ترويها الأحافير".
إنها فكرة رائعة. ربما تخبرنا قصص أخرى أن الحياة على هذا الكوكب ، غريبة أو بعيدة كما هي اليوم ، قد لا تكون مختلفة تمامًا بعد كل شيء.
جين تيمونز (mostlymammoths) كاتبة مستقلة مقيمة في نيو هامبشاير تدوِّن عن علم الحفريات وعلم الآثار على mostmammoths.wordpress.com.
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