About 10 years ago, paleontologists discovered several cave ruins meandering several meters long and about 70 cm wide underground in the Blackleaf Formation in southeastern Montana. From the initial analysis, it can be seen that this cave was not entirely formed by nature, instead, it is probably a cave of some animal.
The researchers said the excavation could have helped the tiny dinosaur survive in hot weather. Unlike animals, reptiles cannot adjust their body temperature. Therefore, in the desert, a cave will be the best shelter to avoid the heat, while in the polar and colder mountains, the cave will help maintain warmth.
As the excavation continued, archaeologists uncovered several fossils of a dinosaur deep within the cave. How can these dinosaurs be in a cave? Was it pulled in after being killed by other animals? After research, paleontologists determined that the dinosaur was the owner of the cave.
The soils in the river were dated in the mid-Cretaceous period – the warm period stretched from about 135 to 115 million years ago. “This is the first fossil record and evidence of excavation in a dinosaur,” the US and Japanese researchers said. The cave, long and filled with sediment, consists of a zigzag tunnel that is more than 2 meters long and about 70 cm wide, similar to the holes that zebra hyena still creates today.
Paleontologists named the newly discovered dinosaur Oryctodromeus cubicularis – a combined Latin and Greek name meaning a burrow.
The most complete specimen of the Oryctodromeus (MOR 1636a) is a fossils belonging to an adult including a part of the skull, dorsal spine, cervical vertebrae, caudal vertebrae, ribs, shoulder blades, forelegs, complete leg bones, …
In addition to these mature specimens, archaeologists unearthed fossils of two other small Oryctodromeus in the cave and were only half the size of an adult individual.
At the end of the stretch is the skeleton of an adult and a young dinosaur. Adults are about 2.1 meters long, weighing from 22 to 32 kg, belonging to a small dinosaur.
In fact, fossils of the Oryctodromeus cubicularis have never been discovered and known before, and more than three are gathered together to show that they died together in the cave.
Oryctodromeus cubicularis was the first dinosaur to show evidence that dinosaurs could dig and live in burrows. It can be said that this is a landmark discovery in exploring the habits of dinosaur life.
Oryctodromeus cubicularis lives in the Cenomanian world, today about 100 million years in Montana, USA. When the dinosaur was just named, the researchers thought it belonged to the Pterodactylidae family, which is a small family of herbivorous dinosaurs.
In recent years, after conducting extensive research, paleontologists have confirmed that the Oryctodromeus cubicularis is a carnivorous dinosaur and changes its taxonomic position to Dibenosaur. Oryctodromeus is classified according to the subfamily Orodrominae and its shape is similar to Hypsilophodon with long hind legs and runs very fast.
Like other Orodrominae, Oryctodromeus also has a very long tail, but their tails are not the same as those of other carnivorous dinosaurs.
Species of the Oryctodromeus show that their tails are very hard, they do not have tendons on the back and tail, instead are a lot of muscle bundles, so the function of the tail is to strengthen the strength of the body. but lose the flexibility.
In addition, the Oryctodromeus jaw, forelegs, pelvis and tail have many special features that help them burrow and adapt to cave life.
Recent discoveries have caused scientists to change the perception that the newly discovered Oryctodromeus specimens in Montana retain nearly intact long veins on the back and tail.
Through the study of new specimens, scholars believe that this type of tendon of the Oryctodromeus functions to regulate the body, allowing them to create a number of more flexible poses that can be adapted to life in cave, completely different from previous research conclusions.
Compared to some typical modern burrowing animals, such as moles, Tachyglossidae, wombats, etc., the Oryctodromeus forelegs are very small in size when compared to body proportions. Oryctodromeus is a dinosaur with two hind legs. With the help of the hind limbs, they can use their beaks and forelegs to slowly burrow.
Although the Oryctodromeus are unable to burrow as efficiently and quickly as the animals mentioned above – they are perfectly adapted to underground life, but these dinosaurs have the ability to move more flexibly. on the ground when attacked. Oryctodromeus can be like wolves, hyenas and rabbits today, they can both live in caves to hide and still move outside to find food.
The body shape of Oryctodromeus is not very large. Adults are only about 2 meters long and weigh 20-30 kg. Small size means they face a lot of predators. In the evolutionary competition, Oryctodromeus gradually found a unique set of measures to protect itself from enemies, that is, it went underground.
Small size is an important condition for living underground. The cave of this dinosaur is only about 70 cm wide, just enough for an adult to pass.
The researchers said the burrowing may have helped the tiny dinosaur survive the hot weather. Unlike animals, reptiles cannot adjust their body temperature. Therefore, in the desert, a cave will be the best shelter to avoid the heat, while in the polar and cold high mountains, the cave will help maintain warmth.