The collective death tragedy in immature dinosaurs

According to a new study published, like today's teenagers, baby dinosaurs often gather together. And similarly, they also gather in places where they should not come.

The group of paleontologists who conducted Gobi desert excavations in western Mongolia discovered evidence of a flock of bird-like dinosaurs when they were subsided in mud on the edge of the lake 90 million years ago.

The sudden death of dinosaurs in mud traps provides rare evidence of the social behavior of dinosaurs. Completely composed of young dinosaurs of the same ornithomimid dinosaur (Sinornithomimus dongi). Dinosaurs show that immature individuals are forced to take care of themselves when adults are busy with nesting or laying eggs.

Paleontologist Paul Sereno of the University of Chicago said: 'There are no new or mature children.'

Located in the skeleton that was prepared for the exhibition plan at Serono's lab and transported back to China at the end of February is the petrified stomach and the last meal of the dinosaurs are preserved. .

Sinornithomimus and other ornithomimid dinosaurs belong to the group of theropod dinosaurs, this group includes tyranosaur. Unlike most other theropods, ornithomimid dinosaurs are herbivores. They are also quite small, have large eyes, run very fast like ostriches.

The event of dense flock of dinosaurs subsided rarely

Sereno, Tan Lin of the Inner Mongolia Department of Land and Resources, and Zhao Xijin - a professor at Beijing and China Academy, directed the fossil-seeking expedition in 2001. The members of the group also included. consists of University of Montana paleontologist David Varricchio (MSU), Jeffrey Wilson of the University of Michigan and Gabrielle Lyon of the Expedition Project. This finding is published in detail in the December 2008 issue of Acta Palaeontologica Polonica, an excavation funded by the National Geographic Society, the David and Lucile Packard Foundation.

Varricchio said: 'The discovery of dinosaurs is extremely rare mud trap found in existing animals. The most typical examples are ungulate mammals such as water buffaloes in Australia or wild horses in West America.

As it approached the lake that today became the Gobi desert in Mongolia, the herd of Sinornithomimus dinosaurs were suddenly trapped hopelessly in the mud 90 million years ago. (Artwork: Todd Marshall, courtesy of Project Exploration)

Other herds, including predominantly or all of the immature, belong to dinosaur groups: sauropods, theropod, ankylosaur, ceratopsian and ornithopods. Although modern birds evolved from dinosaurs, this concentration of young individuals is rare in modern birds.Similarly, immature animals of terrestrial vertebrates do not tend to gather together, only humans, crows and ostriches are the exception. When adults are busy with their own work, immature children like to gather together perhaps because they take years to mature in terms of reproduction.

Over 25 individuals

A Chinese geographer discovered the first bones of the dinosaurs in 1978 at the foot of a small hill in the desolate area of ​​the Gobi desert. 20 years later, the Central Japanese team unearthed the first skeletons, naming the Sinornithomimus dinosaurs (meaning 'imitators of Chinese birds' ).

Sereno and his colleagues then opened a large mine, tracing each skeleton down the bottom of the hill. A total of 25 individuals were excavated from this location. They range in age from 1 to 7 years, based on their annual growth rings on their bones.

The team recorded the location of all the bones along with details of the rock layer to find out how many individuals of the same species die in the same place. The skeletons are also well preserved, most of them returning in one direction, indicating that they died together in a short period of time.

Slowly death

Details have provided crucial evidence for the ancient tragedy. Two of the skeletons lie on top of each other. Although most skeletons are located on a flat surface, their hind legs are deeply stuck to the mud below. Only the hip bones were missing, probably the work of scavengers that carried on the most flesh of the corpse shortly after the dinosaurs died.

Sereno said: 'These animals die slowly in the mud trap. Their struggling actions are intended to attract the attention of nearby enemies or scavengers. ' Normally, the weather, scavengers or bones taken away will remove any direct evidence of the cause of death. But this area provided the most obvious evidence of the cause of the death of a dinosaur.

The mark on the mud surrounding the skeletons showed that they had tried to escape but failed. Varricchio said he was both pleased and sad because of what was revealed. 'I'm sad because I know how those animals die. It is a strange feeling, and this is also the only time I feel like that. '

Besides the composition and behavior of the group, the excavation site also provides knowledge of both the smallest bones in the skull and the skeleton.

Sereno said: 'We even know the size of the eyeball. Sinornithomimus may have been set to become one of the most well-known dinosaurs in the world. '