In Earth's long history, dinosaurs have been the masters of this planet. Although they became extinct at the end of the Cretaceous period, about 66 million years ago, the fossils they left behind have become valuable clues to our study of the history of the earth, the history of life, and even the living habits of the dinosaurs themselves. Of all the dinosaur fossils, footprint fossils provide us with a different way of understanding dinosaurs in a way that is different from bone fossils, if bone fossils can help us know what happened to dinosaur fossils, then footprint fossils describe what they did during their lifetime. Today, let's explore these time-traveling imprints, uncover the stories behind them, and let's start with how to collect dinosaur fossils.
Collecting fossilized dinosaur footprints is usually a step in the following steps:
- Site selection, choosing exposed rock formations or open-pit deposits, which are often more likely to find fossilized dinosaur footprints.
- Collecting samples, measuring size, and measuring the length, width, and depth of footprints will help scientists understand the size of dinosaurs and how they walked.
- Analyze the footprint characteristics, observe the shape of the footprint, the index, the texture of the soles of the feet, and compare them with known dinosaur footprints. This makes it possible to guess what type of dinosaur the owner of the footprint might be, and even to infer the dinosaur's speed and walking style.
- Reconstructing dinosaur behavior, a large number of footprints may indicate that dinosaurs once formed a group, while different footprint types may suggest different ways of walking, such as running, traveling, or staying. Such research can help us better understand the lifestyle and ecological environment of ancient dinosaurs.
A scientist collects dinosaur footprints, she uses some plasticine to enclose the dinosaur footprints, and then coats the footprints with silicone rubber, and when the silicone rubber is dry, the entire footprint can be torn off and brought back for study.
There is also a difference between footprints and footprints, normal human footprints are concave, dinosaurs also have concave footprints, but when the concave footprints are filled in, the stratum that originally formed the footprints is eroded, and convex footprints can be formed, which protrudes from the surface and can intuitively reflect the thumb prints and skin marks that are difficult to observe. In addition to these two types of common dinosaur footprint fossils, if the stratum is very soft, dinosaurs will also appear in the underlying matrix when they walk over, and the lower the stratum, the smaller the deformation, except for the traces formed on the stratum in direct contact, the others are called phantoms. The trouble with the illusion is that it is impossible to determine which layer is the original footprint, unless it leaves some kind of crucial evidence such as scales or fold marks on the dinosaur's feet, gravel and mud crevices, ripple marks, or overlapping raindrops.
With these footprints, we can roughly identify the owner who left them. Scientists generally divide dinosaurs into sauropods and ornithischians based on the difference in pelvis, but paleontologists have difficulty judging what dinosaurs' pelvis looked like based on footprints, so they can only be divided into regilian families, genera and species.
Ideally, dinosaur footprints and dinosaur fossils can be found at the same fossil site very close to each other, but this is almost impossible, because the conditions for the formation of the two are different, the formation of footprints requires a long period of surface exposure in order to dry and form, but this is extremely unfavorable to the preservation of dinosaur corpses, long-term exposure to the surface, dinosaur corpses are easy to be picked up by scavengers; on the other hand, the preservation of dinosaur corpses requires water currents to carry sediment to quickly bury them, but this hydrodynamic condition is often the culprit of destroying footprints.
First of all, let's distinguish between quadruped and bipedal dinosaurs, the four-legged ones are called sauropod dinosaurs, they have a smaller head, a longer neck and tail, and thick limbs, including brontosaurus, brachiosaurus, diplodocus, etc. Its body is heavy, and the four-legged footprints generally show front and rear footprints of different sizes and shapes, and the back footprints are larger than the front footprints, and they can have as many as four or five toes. Four-legged dinosaur footprints are far less common than bipedal footprints because most quadruped dinosaurs prefer dry or woody habitats where their footprints are not preserved, while bipedal footprints are the most prevalent and often contain similarly shaped fingerprint left and right sequences, each of which in turn contains three main toe imprints, so they are often referred to as "three-toe prints". But in reality most bipedal dinosaurs had four to five toes on each foot, but one of the toes was small and high on the inside of the back of the foot, and even if there were traces on the fossils, the thumb footprints were usually small and shallow, and the fifth toe slowly degenerated during evolution.
↑↑↑
Degenerate dinosaur toes
↑↑↑
Very shallow thumb prints in degeneration
Bipedal dinosaurs contain herbivorous bipedal walking ornithistia and carnivorous theropods, which can be distinguished by the tips of the toes and heels: Ornithopod footprints are characterized by their footprints that are usually wider and more rounded in the back (U-shaped) than those of theropods. Animal-foot footprints, on the other hand, tend to have large, sharp scratches in the shape of an inverted V or cone, and a triangular or wedge-shaped (V-shaped) part of the hind half. Theropods can be further divided into species, in the beginning, people used 20 cm as the watershed of footprints, < 20 cm theropods were called hyposiosaurs, > 20 cm were called carnivorous dragons, and now more classifications from slender to stout are used: like sandpiper tracks, Angel dragon tracks, and solid brontosaurus tracks.
↑ It can be distinguished by the tip of the toe and the heel
↑ Sharp claw marks of theropods
At the beginning of the article, we mentioned that the fossilized dinosaur footprints let us know about the life of the dinosaurs, and through these various footprints, we can also reconstruct the behavior of the dinosaurs at that time. The famous American paleontologist Ostrom discovered that the platypus dragons lived in groups and had a certain social nature by observing the footprints of platypus dragons. Another footprint found in China shows that the dinosaur could swim: it used the ends of its hind limbs to pick up water, just touching the bottom of the river. ↓↓↓
↑↑↑
Nine dinosaurs left footprints in this area at a short interval, indicating that dinosaurs were social animals
Dinosaurs not only left the world with information about the state of the earth at that time, but also added a mysterious color to some ancient legends, such as the footprints of the "Divine Eagle" in the Chabu area of Inner Mongolia are actually three-toed carnivorous theropod footprints; the "ghost footprints" of Zhenfeng in Guizhou are actually the biological footprints of the early Triassic before the dinosaur era, and the real identity of the Tibetan "King Gesar" who can fly on the wall is actually just a dinosaur that walks relatively fast.
Dinosaur footprint fossils, as a special paleontological remains, provide us with a unique perspective to explore these vast creatures that once existed on Earth, and each new footprint discovery is a new chapter in the dialogue between us and these ancient creatures. Dear readers, have you seen some strange traces, they may be the footprints left by dinosaurs tens of millions of years ago?
The reprinted content represents the author's views only
It does not represent the position of the Institute of Geology and Geosciences of the Chinese Academy of Sciences
If you need to reprint, please contact the original official account