Experts said that it is like a Bian's beast, and it loves to make holes and change teeth.
A few days ago, the 208 geological team of Chongqing Geology and Mining Bureau participated in the research of the research results on the associated animals of the Yunyang dinosaur fauna in the Chinese core journal "Journal of Palaeogeography" online, which also proves that in the early Middle Jurassic, there was a "hometown" of the trilogy of dinosaurs similar to beavers, porcupines, and voles——— and the surrounding areas of Pu'an Township and surrounding areas.
The upstream news reporter also published "The 'Nail Rake Beast' Debuts Yunyang Dinosaur Adds a New 'Neighbor'", What Is the Name Of This Animal? What Are Its Habits? The Upstream News Reporter interviewed Wang Ping, one of the authors of the article, a researcher of the 208 Geological Team of the Chongqing Municipal Bureau of Geology and Mineral Resources.
Wang Ping said that 170 million years ago, the little neighbor of the Yunyang dinosaur was not called the "nail rake beast", which may be everyone's nickname for it, but the teeth are shaped like nail rakes. Its scientific name is like Bian's beast, and its appearance is similar to that of a vole, with sharp teeth like a "nail rake" and "changing teeth".
The mandible of this study was excavated in the Xintiangou Formation, and the Pu'an Yunyang Dragon and the Modaoxi Three Gorges Dragon were also found in the Xintiangou Formation. "It can also be seen that in the era when Yunyang Long lived, there were 'little neighbors' like Bian's beasts. ”
The posterior canines of the maxilla are square, with a total of 3 rows of cusps, among which there are 2 cusps on the inner side of the posterior canines and 3 cusps on the middle and outer sides, which resemble a "nail rake", which is conducive to chewing coarse fibers and harder plant branches and leaves, and is a herbivorous reptile similar to mammals.
Studies have shown that these small animals are good at digging burrows, and generally live in underground burrows, usually inhabiting warm broad-leaved dense forests, shrub forests, river valleys with gentle and deep currents, and lakeside shores. For the Bian-like beasts, there is plenty of food in these places, and it is easier to make holes and settle down.
"In the CT scan of the fossils, we also found an interesting phenomenon: it seems that the Bian beast will 'change teeth'. ”
Wang Ping said that some scholars have been studying the way of tooth replacement in triodonts before. Most vertebrate teeth are replaced longitudinally, that is, new teeth grow to replace old teeth, which is the way humans replace them. The trilodont, on the other hand, adopts a lateral tooth swapping strategy: new teeth germinate from the back of the dentition and move forward. The teeth of some living mammals, such as elephants, manatees, frost rats, etc., are also replaced horizontally, and the number of teeth in these animals is constant, and the age of the individual can be determined according to the rate of replacement. "If the rate of tooth replacement in the trinodont can be quantified, it would be a good breakthrough point to judge the ontogeny of fossils. ”
In addition to the Bian's beast, what other small neighbors did the 170-million-year-old Yunyang dinosaur have?
According to Wang Ping, small animals such as turtles, crocodiles, and amphibians with similar growth environments to Bian's beasts all lived in that era.
Trinodonts had a global distribution in the Late Triassic-Early Jurassic, then tended to decline, and its distribution in northeastern Asia could continue into the Early Cretaceous.
"The fossils in this study were excavated and stored in 2016 and 2020, one is a skull, and the other is a mandible, and the mandible fossil is also the oldest trilodont fossil found in the Sichuan Basin. Wang Ping said that the discovery of Bian's beast has enriched the types of companion animal members of the Yunyang dinosaur fauna, and has once again proved the diversity of the morphology and geographical distribution of the trilodont.
Upstream news reporter Chen Zhu Photo provided by the interviewee