Dinosaurs traveled in herds and dinosaur eggs in Argentina

Jurassic graveyard reveals oldest evidence that dinosaurs traveled in herds.The graveyard had more than 100 fossilized dinosaur eggs. A Jurassic cemetery in Patagonia, Argentina, contains more than 100 fossil eggs and the bones of 80 Musaosaur Patagonicus dinosaurs, ranging in age from hatching to adult. A new study has found that the remains of dinosaurs indicate that these ancient animals lived in herds 192 million years ago.

dinosaurs traveled in herds

The researchers said the discovery is the oldest evidence that dinosaurs lived in herds and indicates that dinosaurs exhibited complex social and social behavior 40 million years earlier than previously thought. The tomb also shows that the herd had an endoskeleton. For example, small dinosaurs traveled in herds and they lived (and died) together in groups. It’s rare to find signs of preserved behavior in dinosaur bones (dinosaurs traveled in herds), but “we now have evidence of a complex social behavioral structure within the herd,” said study lead author Diego Bol, professor at the Museo Paleontologico Egidio Viroglio and the National Scientific and Technological Institute. Institute: The Research Council of Paleontologists of Argentina (CONICET).

100 fossilized dinosaur eggs

“I would say this is one of the most important fossil discoveries of the year,” said Michael Damick, an assistant professor in the department of biology at Adelphi University in New York who was not involved in the study. “It’s very exciting to have so many individuals of one type of fossil, from embryos to adults.” Since 2002, Ball and colleagues have spent part of their field season drilling a relatively small outcrop of about 0.3 square miles (1 square kilometer) in the Laguna Colorada Formation in southern Patagonia.

The formation is known to contain M. patagonicus fossils, and was inappropriately given a scientific name meaning “mouse lizard” based on small fossil hatching specimens found in 1979. Over the years, Paul’s team has discovered more than 100 eggs and fossils of dozens of new M. patagonicus individuals. The specimens include dinosaurs from six different life stages, ranging from fetus to adult. Previous studies showed that M. patagonicus laid eggs with smooth, leathery shells and probably walked on all fours as infants, and switched to bipedal walking shortly after their first birthday. But now, Paul and his colleagues have enough evidence to prove that these sauropodomorphs – a group of long-necked herbivorous dinosaurs – lived in herds.

dinosaur eggs

Illustration of the breeding site of a herd of Mussaurus patagonicus, showing individuals of various age groups, including newborns in nests, young dinosaurs, and now young adults in Patagonia. (Photo credit: Jorge Gonzalez) His team speculates that the herd began as a transition of sauropodomorphs from small dinosaurs to giant dinosaurs. For most of the Triassic period (from 252 million to 201 million years ago), dinosaurs were small, roughly the size of horses.

But between 227 million and 208 million years ago, sauropodomorphs grew larger, and their bodies changed in size by two orders of magnitude, the researchers wrote in the study. But they still lay small eggs. In the case of M. patagonicus, its young hatched from eggs the size of a hen and grew to about 3,300 lb (1,505 kg), or about the weight of a hippo.

In other words, m. Young Patagonikos had to grow to a gigantic size in just a few years. “This is the time when they need to eat a lot of food to grow, but they don’t have the size to fend for themselves and they don’t have the experience and knowledge,” Ball told Live Science. “So being in the herd really protects you during those very sensitive and vulnerable stages of your life.” A nest of fossil eggs dating back 192 million years from the sauropodomorph dinosaur Musaurus patagonicus found in southern Patagonia, Argentina. (Photo credit: Diego Boo)

Nests and groups

At the site, paleontologists found eggs arranged in groups, evidence that either male or female M. patagonicus dug holes that the females then used as nests. The survey said there are eight to 30 eggs in these nests. X-ray computed tomography (CT) imaging of five of these nests showed that the eggs were arranged in two to three layers and contained embryonic bones from M. patagonicus. He said the large number of egg groups at the site indicated that it was a common dinosaur breeding site and dinosaurs traveled in herds.

A 192-million-year-old fossil egg of Mussaurus patagonicus from southern Patagonia, Argentina. (Image credit: Roger Smith). The site contained other groups of dinosaurs in various stages of life, including a group of 11 juveniles younger than one year old, two adults found together and nine nearly mature adults. maybe m. Paul said that patagonicus lived together in flocks, but dinosaurs of different ages roamed together.

These dinosaurs likely died from dehydration. “We know this place was seasonal, and there are signs of drying out in the sediments,” Ball said. Many of the animals died in the resting position, which means that they died while lying down and then were covered by the wind. Damick told Live Science in an email that it’s “extremely rare” to find so many preserved dinosaurs in one place. “It is much more interesting and important that these animals live in social groups.

dinosaurs living in the herd

People tend to think of extinct groups like these sauropodomorphs as an evolutionary ‘dead end’, but that doesn’t mean they didn’t have advanced behaviors like socialization…” In fact, “social life may have been important to the evolutionary success of sauropods, the largest animals that ever walked the earth,” Damick said.

The gigantic fossil displays are the oldest evidence of dinosaurs living in the herd. A wealth of new sauropod eggs and skeletons indicates that these Jurassic herbivores were among the first dinosaurs to travel in groups by age. The long-necked dinosaur Mussaurus changed from walking as a juvenile to walking on its hind legs in adulthood. A wealth of fossils found in Patagonia now indicates that this species was the first to migrate into age-separated herds.

About 193 million years ago in what is now Argentina, a group of 11 dinosaurs died within a few feet of each other. It is not clear how. Perhaps they had succumbed to a drought, as the spring or summer sun baked the ephemeral lake bed on which they had gathered. Or perhaps they died in the raging dust storm that buried their bodies in a mound of silt. What’s more certain is their age: none of these dinosaurs likely made it to their second birthday.

Brachiosaurus or Brontosaurus

The montage, revealed today in Scientific Reports, is one of several surprising new fossils of Mussaurus patagonicus, a distant ancestral cousin of famous long-necked dinosaurs such as Brachiosaurus or Brontosaurus. The remains include more than a hundred new moussaur eggs and 69 new skeletal fossils, some of which appear in groups of dinosaurs similar in size and roughly the same age.

The study team interprets this grouping as evidence that Musaurus moved in age-separated herds, along with animals of similar size and age within the group. If so, the discovery gives paleontologists the oldest evidence ever of this herding behavior within dinosaurs. “We know very little about dinosaur behavior, but what we do know is based on dinosaurs from the Cretaceous period to very late,” says study leader and National Geographic explorer Diego Bol of the Edigio Ferrruglio Museum of Paleontology in Trelew, Argentina. “We have very little or no information about the behavior of dinosaurs early in their history.”

Laguna Colorada Formation in Argentina

Mussaurus is a type of dinosaur called a sauropodomorph, known to science since the 1970s based on 11 fossils found in the Laguna Colorada Formation in Argentina. Other sites around the world have alluded to social behavior among the Sorobodomorph’s cousins in Mossore. Sites in Germany preserve assemblages containing many Plateosaurus fossils, while sites in South Africa preserve nesting sites and eggs of the related Massospondylus.

But Kimmy Chappelle, a postdoctoral researcher at the American Museum of Natural History who was not involved in the new study, stresses how surprising the latest collection of fossils from the Mossaurus site is. “You have eggs, [and] individuals — not just individuals of the same age, but individuals of different ages. That’s just crazy,” she says. Rock] to stay inside the block? Wonderful.”

Pros and cons of herbs

Many large-bodied herbivores today move in flocks, and the basic calculus remains the same today as it was in Mossore 190 million years ago. Herring comes with pros and cons, notes Temple University paleontologist Timothy Myers, who was not involved in the new study. On the other hand, moving in large groups offers greater protection from predators, leaving everyone in that group less time to watch and more time to feed. On the other hand, groups should share food, and the risk of disease and parasites is high.

For a herd to function well, Myers says, the animals within the herd must be in sync, which can be difficult for animals that change shape dramatically with age. In the Mossaurus, the hatchlings began to be about the size of a human’s palm, growing to 20 pounds and two feet long at the hip by age one, and by adulthood they weighed more than 3,300 pounds — the size of an adult moose roughly twice the mass.

sauropods and sauropodomorphs

This is where age separation comes in. “Basically, the cost of timing your behavior goes up as you watch the difference in body size increase,” Myers says. “For things like sauropods and sauropodomorphs, it is certainly more convenient for them to form these swarms of immature individuals that are distinct from adults.” That said, it is difficult to infer such social behavior or any form of social behavior from the fossil record.

Tracking fossils, like tracking sites, can help, and for some dinosaurs much more recently than Mussaurus, such preserved tracks have shown signs of multigenerational herds. Skeletal evidence can also hint at social behavior, if paleontologists find groups of skeletons that were all buried at once. Without that significant evidence, any two skeletons within the set may have been from animals that lived and died separately over the years.


Pol and his colleagues have been excavating the Mussaurus site for the past two decades, dramatically improving their understanding of dinosaurs. For example, researchers now have a better understanding of how Mussaurus’ body changed as it grew; They believe that dinosaurs went from walking in adolescence to walking on their hind legs in adulthood. New research has also shown that Mussaurus laid soft, leathery eggs, suggesting that the dinosaurs buried rather than laid their eggs. (Learn more about how new technology is reinventing dinosaurs like Mussaurus.)

The biggest surprise at the site came in 2003, when Pol found a stone block containing a group of 11 young individuals. “I remember picking up part of the concussion and seeing that there was an upper part of the skull and neck going into the rock,” says Pol. “I knew it was something different.” Other fossils at the site also show signs of grouped dinosaurs. The earliest known fossils of young Mussaurus chicks clumped together. The new excavation also found two adults whose bodies were almost intertwined.

But to see if these animals actually died in groups and not in the same place at different times, co-authors of the study led by Roger Smith of the University of the Witwatersrand, Johannesburg, South Africa, had to examine the sediments at the site. carefully. Smith’s research found that there are three distinct layers of Mussaurus fossils at the site, and that many of the site’s fossils and nesting sites share the same layer, meaning each was buried at the same time.

Mussaurus fossil embryos

The sedimentary rock surrounding the fossils likely formed from windblown dust, likely deposited during a dust storm. The team also used a series of techniques to confirm that all the dinosaurs were moss and to examine the age and size of the dinosaurs. In 2017, POL sent 30 eggs to Grenoble, France, to be examined using the European Synchrotron Radiation Facility, one of the brightest X-ray sources in the world. Many of them contained Mussaurus fossil embryos.

Pol and his colleagues also took samples of some dinosaur bones to look at their internal structures, which can reveal information about age and growth patterns. All of the fossils in the group of 11 individuals are roughly the same size, possibly weighing between 18 and 24 pounds when they went extinct. The bone samples suggest that if the young Mussaurus grew up in seasonal groups, the juveniles in the group were likely less than a year old when they died.

The Mussaurus site shows the juveniles forming age groups at least seasonally, but the behavior of the adults is somewhat definite. For one thing, the site does not contain groups of many adult Mussaurus, so there is no direct evidence of adult herds. In living reptiles, it is not uncommon for juveniles to congregate and then divide in adulthood. Again, the groups of juveniles are found within a Mussaurus nesting site, which may indicate that the juveniles were part of a larger flock that went to the nesting site to breed.

Dinosaurs traveled in herds

The herbivorous dinosaurs of the early Jurassic lived in age-separated herds, dinosaurs traveled in herds & dinosaurs traveled in herds Paleontologists have analyzed an extraordinary fossil assemblage from the Laguna Colorada Formation in Patagonia, Argentina, consisting of 193 million-year-old skeletal remains (Early Jurassic Era) and eggs of the early sauropodomorph dinosaur Musaurus patagonicus, ranging from embryonic to entire areas. . developed. Adult.

Reconstruction of the Mussaurus patagonicus herd. Image credit: Jorge González. Dr. Jahandar Ramzani, a researcher in the Department of Earth, Atmospheric and Planetary Sciences at MIT, said: “People already knew that in the late Jurassic and Cretaceous periods, large herbivorous dinosaurs exhibited social behavior, lived in herds and dinosaurs traveled in herds, and had nesting sites. “

Mussaurus patagonicus

“But the question has always been, when was the first time this type of cowboy behavior occurred?” Dr. Ramzani and his colleagues examined the fossil skeletons of 80 individuals and more than 100 eggs of Mussaurus patagonicus from the Laguna Colorada Formation in southern Patagonia. “Such a protected site would surely provide us with a lot of information about how dinosaurs lived (dinosaurs traveled in herds),” said Dr. Diego Pol, a paleontologist at CONICET.

Paleontologists found that most of the eggs were arranged in groups of eight to 30 eggs. X-ray images of five of these groups revealed that the eggs contained Mussaurus patagonicus embryos and were arranged in two or three layers within trenches, suggesting that they were contained within nests within a common breeding site.

The researchers analyzed the size and type of skeletal bone tissue to determine the age of the fossil individuals. They identified a group of 11 youths under one year of age, two adults who were found together, and nine individuals who were older than the youth but younger than the adults (dinosaurs traveled in herds).

behavior in dinosaurs

They suggest that the presence of age-specific groups of individuals in the same location may indicate that Mussaurus patagonicus lived in herds throughout its life, but mainly associated its age with others within the herd. “The young people did not follow their parents in the small family structure. There is a large community structure where adults share and participate in the raising of the entire community, “said Dr. Ramzani.

Mussaurus patagonicus specimens collected from the Laguna Colorada Formation, Patagonia, Argentina. The team dated the ancient sediments among the fossils and determined that the Mussaurus patagonicus swarm dates back to about 193 million years ago, during the early Jurassic period. The results represent the earliest evidence of social grazing among dinosaurs, some 40 million years earlier than other dinosaur records.

evolutionary success of dinosaurs

We have now observed and documented this early social behavior in dinosaurs,” said Dr. Ramzani. “This now raises the question of whether herd life may have played a role in the early evolutionary success of dinosaurs. This gives us some clues as to how dinosaurs evolved. The authors suspect that two other types of primitive dinosaurs, Masspondylus from South Africa and Lufengosaurus from China, also lived in herds at the same time.

If several different lines of dinosaurs traveled in herds, they believe that social behavior may have evolved earlier, perhaps like their common ancestor, in the Late Triassic era, just days before extinction. Many other animals were eliminated prematurely. “We now know that animal husbandry was developing 193 million years ago,” said Dr. Ramzani.

This is the first confirmed evidence of social behavior in dinosaurs. But paleontological understanding says that if you find social behavior in this type of dinosaur right now, it must have originated earlier. An article on the findings was published in the Journal Scientific Reports.

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