In a recent study, scientists delved into an "important" question: What is it like to be eaten by a juvenile Tyrannosaurus rex?
The answer is that it may feel like being eaten by a hyena, or being eaten by a crocodile. To reach this conclusion, paleontologists first found a fossil vertebrae of Edmontosaurus with bite marks, and believed that the bite marks came from a young Tyrannosaurus rex (king tyrannosaurus, scientific name Tyrannosaurus rex). Edmonton's dragon, a dinosaur of the duck-billed dinosaur family, found that these bite marks matched the Tyrannosaurus rex fossils between the ages of 11 and 12 years by measuring the spacing and size of the bite holes of the fossils and comparing them with the fossils of T. rex of different ages.
Adult T. rex, juvenile T. rex, and human body size comparison
After confirming that these were wounds left by Tyrannosaurus rex, the researchers began trying to replicate the depth and shape of the wounds. They mounted a tooth made of dental-grade cobalt-chromium alloy on an "electromechanical test system" and used it to "bite" a cow bone. They then examined the wound on the cow bone for similarities with the bite marks on the fossilized Edmonton dragon spine. They found that juvenile Tyrannosaurus rex had a bite force of up to 5600 cattle, while humans had a bite force of only 300 cattle. Adult or quasi-adult T. rex can have a bite force of up to 35,000 cattle, enough to crush the bones of prey — which can be found in the fossilized droppings of T. rex — and even enough to crush a car.
From infancy to adulthood, T. rex bites increased dramatically by a factor of 6, because they experienced an important "puberty" that occurred in juvenile T. rexes around the age of 14. Bite force increases sharply during this time and then gradually decreases between the ages of 16 and 18. From the age of 12 to 18, in just a few years, Tyrannosaurus rex can grow in size by 5 times, and the annual food consumption can increase by thousands of kilograms. Some scientists have expressed doubts about this staggering growth rate. They argue that these so-called "juvenile Tyrannosaurus rex" actually represent a completely different species: nanotyrannus. The effectiveness of the genus Dwarf Tyrannosaurus has been a major controversy in the paleontological community for decades.
From top to bottom, the weight of Tyrannosaurus, Lepidoptera, Serpentine, and Albertaurus tends with age
Studies of the amazing bite force of juvenile T. rex (although not as striking as adult T. rex) further confirm that they are indeed juvenile T. rex specimens, not different species. It may also be important to understand how the Tyrannosaurus rex's predation changes over the course of a lifetime. Don't confuse "experimental paleontology" with research from a movie like Jurassic Park, because the former can really provide important information about species that were extinct 65 million years ago.
The study, published recently in the journal PeerJ, features three authors from the University of Wisconsin-Oshkosh, the University of California, Berkeley, and the University of East Carolina.
Fan wai: Do trilobites bite people?
Imagine traveling back hundreds of millions of years to a sunny beach, and when you're playing in the water, you suddenly notice what seems to be something under your feet. You look down and you find a trilobite. At this point, you may be the first to come up with a terrible idea: will trilobites bite people?
Of course, trilobites became extinct 252 million years ago, and now we don't have to worry about actually being bitten by them. However, this is indeed a rather complex issue.
Trilobites became extinct 252 million years ago, and now we don't have to worry about actually being bitten by them
First, we must define what is "biting". If this definition involves the structure of the "jaw" (similar structures in invertebrates are often referred to as "jaws"), then the answer is no, and you don't have to worry about traveling hundreds of millions of years ago. Humans have upper and lower jaws, and this structure did not evolve until 440 million years ago in placoderms – they are also considered the most primitive jawed animals. Trilobites do not have jaws like humans, fish or dogs. However, if a creature wants to bite, does it have to have an upper and lower jaw? This is the philosopher's question. The question for paleontologists is: What structure can the trilobite replace the role of the jaw?
First, trilobita contains 20,000 species in 10 orders, 150 families, 5,000 genera, and is known for its rich and diverse ecological niches. Trilobites can live in a wide variety of marine habitats, including the seafloor and coral reefs, and they can also float in water bodies or move in deep water.
The jaw base and suborbital plate structure of trilobites
Most early trilobites were carnivores or scavengers. They usually crawl on the ocean floor and feed on a variety of small creatures, including dead trilobites, worms and other small animals. Some trilobites have a leg-like structure on both sides of the body called "gnathobase", somewhat like ratworts. The jaw bases on either side of trilobites can grab and pass food along the midline, so their "feeding" occurs mainly on the midline. Trilobites may cling worms or other prey to a hard midline, tearing and crushing food through the base of their jaws, feeding it into their mouths. The final processing, the "chewing", occurs during which the trilobite crushes the food on the hypostome with a jaw base. The suborbital plate, made up of a hard exoskeleton, is a large, flattened plate-like structure of the trilobite's head and is the closest part of the trilobite to the jaw. Basically, the suborbital plate is equivalent to a plate of food.
If the suborbital plate of the trilobite is large and fixed to the exoskeleton, then it is likely to be a predator. The various lower plates tell us that different species of trilobites specialize in preying on specific types of prey. Some lower plates also have ridged or forked bulges that can be used to cut prey. If the suborbital plates of the trilobite are not well glued together, but only connect two points like a hinge, then it is likely to filter the sediment for a living, using the suborbital plate to pick up the sediment and obtain food from it. Of course, these are only a small part of trilobite ecology. As a richly diverse population, trilobites have a variety of different predation mechanisms and food preferences, such as a peculiar trilobite that can symbiotic with sulfur-producing bacteria deep in the ocean. Despite not having upper and lower jaws, trilobites have achieved the process of "biting" in their own unique way and have developed a variety of different feeding methods. (Ren Tian)