2021-05-04

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By yqqlm yqqlm

On March 19, 2021, paleontologists conducted a detailed study of an Ankylosaurus fossil from the Gobi Desert in southern Mongolia, and found that the forelimbs of this Cretaceous Ankylosaurus were like a large shovel, which might be in the Gobi. A pit was dug out in the desert to protect the soft abdomen, or to search for water sources, plant roots and minerals. Related research results were published in the journal “Science Reports.”

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In the Gobi “Anonymous Ankylosaurus”

Speaking of which, the life experience of this new Ankylosaurus fossil is also quite bumpy.

From 1972 to 1973, the Soviet-Mongolia joint biological expedition team discovered it for the first time in the Gobi Desert of Mongolia. But when the expedition team was preparing to bring it back to the laboratory, due to lack of materials and time constraints, it had to give up temporarily. In a flash of thirty years, during this period, countless expeditions passed by, and the yellow sand in the sky had already thickly concealed the fossils. It was not until 2008 that this Cretaceous Ankylosaurus, which was forgotten in the Gobi Desert, was re-excavated.

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Excavation site photos |References[1]

Perhaps because it has been eroded by wind and sand, the skull of this ankylosaurus is nowhere to be found, only a torso is left, more than two meters long, and the side scales are clear. There is almost no deformation of the bones, and his hands and feet are curled up on his abdomen, as if he is asleep and quiet. This posture is usually interpreted as being buried alive in a sandstorm, dying on the spot, too late to struggle.

Unfortunately, most of the other Ankylosaurus fossils in the same strata only retain their skulls, so they cannot be compared with the newly discovered Ankylosaurus this time. This also means that it cannot be classified accurately, and this ankylosaurus cannot have a name, and it is forced to become an “anonymous ankylosaurus”. The number (MPC-D 100/1359) will be its long-term only pronoun.

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Number (MPC -D 100/1359) Fossil photos and top view of bones, (c) The white bones are reserved parts, and the black ones are missing | References [1]

Even if it is headless and nameless, it cannot hide its shining points . This pair of torso fossils with scaly armor not only provided valuable materials for studying the evolution of the ankylosaurus body structure, but also a number of skeletal features showed adaptability for excavation, which means that the “Anonymous Ankylosaurus” may have mastered the excavation. The ability.

Corgi in the dragon, with short but powerful legs

Generally speaking, most vertebrates who have studied digging technology have slender front paws, which can be used for excavation. Make some achievements. Paleontologists believe that Ankylosaurus adopted a different strategy. Take this “Anonymous Ankylosaurus” as an example. Its shoulder straps and forelimb bones are very strong, and its metacarpal bones are short and wide, arranged in a shallow arc.

In this way, although the front paws appear short and wide, they are actually hard and powerful, like a large shovel. It can be imagined as a short-legged Corgi equipped with mechanical claws. Although the legs are short, they have super strong digging ability. Therefore, when you travel back to the Gobi Desert in the Cretaceous Period, you may see a clumsy Ankylosaurus, waving its thick shovel-shaped claws, struggling to dig pits in the sand.

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Want to be Old excavators must pay attention to stability. The “Anonymous Ankylosaurus” is covered with a thick layer of scale armor and moves slowly. Once the car is overturned, it is difficult to get up. In this regard, its bones have been changed accordingly to make it better support the bulky body and improve the stability of the body during excavation.

First of all, the sacral rod of “Ankylosaurus” contains 9 dorsal vertebrae.

The anterior rod is a unique rod-like structure in Ankylosaurus, formed by the healing of the back half of the dorsal vertebrae. The anterior rod of most Ankylosaurus dinosaurs only contains 3-4 dorsal vertebrae. There are as many as 9 “Anonymous Ankylosaurus”, which can provide better support and protection and help the body bear more weight.

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“Anonymous Armor The number of dorsal vertebrae contained in the sacral rod of “Long” and its comparison | Reference [1]

Secondly, the number of phalanges in “Ankylosaurus” is less than that of the early Ankylosaurus.

Studies have found that over time, the number of phalanges of ankylosaurus dinosaurs will gradually decrease. This phenomenon also exists in the sauropod dinosaurs, the largest land animal on the planet. In order to adapt to a large body weight, the number of dinosaur phalanges has decreased even more surprisingly. For example, some Titansaurus has completely lost the phalanges of the fifth toe during the evolution process. At the same time, the phalanx of the forelimbs was constantly lost, gradually turning into columnar limbs.

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Sauropods The number of phalanges in dinosaurs has evolved, and the number of (bh) phalanges has been decreasing. The V toes of the “Post-concavocerus” as Titanosaurus have lost complete phalanges | References [2]

Not only that, but also phalanges The reduction in the number will also reduce the flexibility of the hind limbs, in exchange for higher stability, so that the “Anonymous Ankylosaurus” can firmly hold the body on the ground when digging a hole with its head, and avoid shaking left and right.

Finally, “Anonymous Ankylosaurus” is very stable.

Fossils show that its 3-6 ribs all have irregular bone plate-like protrusions and overlap each other to form a large bone plate between the ribs. This structure will inevitably lower the trunk. Flexibility. Coupled with its fusiform body shape, wide in the middle and narrow in the front and back, it further helps the “Anonymous Ankylosaurus” to keep its body straight when digging or wagging its tail. It can be seen that the “Anonymous Ankylosaurus” has spent a lot of thought in the evolution in order to be a stable “excavator”.

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“Anonymous Armor Side view of the skeleton of “Dragon”, the yellow circle is an irregular bone plate between 3-6 ribs, (d) with scale armor, (e) without scale armor | Reference [1]

Excavation Technology is just my protective color

Why does Ankylosaurus possess mining skills? Scientists suspect that it may be out of self-protection.

Although the Ankylosaurus dinosaurs are covered with heavy scale armor from head to tail, and the tail end is a large bone hammer, and the shoulders can even grow bony spikes, it seems that the defense power has been bursting, but Don’t forget, they also have relatively soft belly. For a long time, people believed that the ultimate defense method of ankylosaurus was to squat down and curl up its limbs to the abdomen, like an all-round iron-clad fortress with no dead ends.

If ankylosaurus can dig, then they can fix their bodies in shallow pits to prevent them from being knocked over by predators. At the same time, the limbs and soft abdomen are hidden under the sand and stone, only the back covered with scales is exposed, and it is integrated with the environment, making it difficult for predators to find themselves. We can also find similar strategies in existing horned lizards.

In addition to becoming a stronger fortress, the advantage of mining is also conducive to foraging. As a herbivorous dinosaur, Ankylosaurus may dig roots for food, or search for groundwater and minerals, just like modern African elephants.

In fact, as early as the 1950s, paleontologists put forward the hypothesis of ankylosaurus excavation, which is also used for self-defense and survival. But so far, the core of this type of hypothesis is still the skeletal characteristics of Ankylosaurus showing the possibility of mining. Because in the stratum containing Ankylosaurus fossils, no caves or other excavations related to it have been found.

But it’s okay. As mentioned in the opening paragraph, humans have discovered dinosaurs that can really punch holes.

It belongs to the Northwestern United States “Digging Dragon”

In the northwestern United States, Montana, there is a large area of ​​Late Cretaceous stratum with various spine buried Animal bones, teeth and eggshells, and their home-underground caves.

In 2007, a study described the first fossil evidence of dinosaur burrowing behavior: paleontologists discovered an underground cave 95 million years ago in Montana. In the deepest part of the cave, lying The three dinosaur bone fossils belong to Oryctodromeus. Therefore, Digbensaurus was also the first dinosaur to be confirmed to have burrowing behavior.

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Under exploration The cave ruins, white artificial plaster, play a protective role | montana.edu

The cave of the digging dragon is about 2 meters long and 70 cm wide. The whole is like a sloping, curved tunnel with a bend. It also connects two small tunnels, only a few centimeters in diameter, which may be a masterpiece of symbiotic small animals. As for the “owner” of this cave, the skeletons of three digging dragons are scattered at the end of the cave. This may have been their nest and storage room, but now it has become a tomb.

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Fossil display, The three digging dragons are one large and two small. The adult individuals are about 2 meters long, and the juvenile individuals are about 1 meter long. The size and width of the cave is enough to be a hiding place for them. In addition, none of the fossils of Digbensaurus has been transported by running water, and there are no carnivorous bite marks and fractured surfaces on the bones. Therefore, the corpses were not brought into the depths of the cave by running water or predators. It is more likely that they lived in the cave before they were alive. In the cave and died in it.

After the death of the digging dragon, the corpse gradually decayed, and wind and sand continued to pour into the cave until it submerged…

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One large and two small, buried underground. Paleontologists can’t help but speculate that Digbensaurus may have parental parenting behavior. Whenever a new life breaks its shell, the adult digbensaurus will take care of the cubs in the cave until the cubs can live alone, thereby increasing the survival rate of the cubs and continuing the population. Although compared with today’s master diggers such as moles and groundhogs, the forelimbs of Dig Benlong are slightly inferior and unable to build a more magnificent underground shelter for itself and its cubs, but it has slender hind limbs that can correct its posture. Avoid predators when searching for food on the ground. Dig Benlong: Digging and escape are both right!

The discovery of digging the Benlong cave also made paleontologists a reverie: When the asteroid exploded on the earth 66 million years ago, whether there was something good at How about the excavated dinosaurs hiding in underground shelters to escape the mass extinction?

In short, the history of the evolution of dinosaurs is a long drama. The “unknown ankylosaurus” that digs holes and the diggersaurus that burrows are just a small part of the daily life of dinosaurs. This group of guys have been constantly changing their body structure and functional form to adapt to life since the first two-legged walk. Apart from digging, they still have terrestrial, arboreal, and even aquatic habitats… Thanks to their unremitting efforts, this drama of life has continued to this day.