Image from the web
The "thief" mentioned here is actually a type of animal, called "thief beast". Speaking of the reason why the thief is "thief", it is necessary to mention the genus "Haramiya" in the order of thief beasts named by the American paleontologist George Simpson as early as 1947.
When scientists name extinct animal species, they generally choose Latin, Greek, Arabic and other words that can be used to reflect the characteristics of animals under the traditional Linnaean naming system. The Aladdin prefix "Haramiya-" in the genus "Haramiya" means "magician or thief", showing the characteristics of "its magical, unknown".
Because before the discovery of the Specimen of the Yanliao Thief in China, such mammal fossil specimens had long been discovered, but they were basically scattered and fragmented materials, and scientists knew very little about them.
Yanliao arboreal mammal group
Although in later studies the genus "Haramiya" was considered to be synonymous with Thomasia, which was named in 1908, and its genus name was invalid, the resulting family Haramiyidae was retained. The word "thief" is a translation of the Chinese, of course, there are other translations, but the translation of "thief beast" is more concise, but also reflects the original meaning, in 2013 by Chinese scholars first translated, and still used to this day.
When it comes to thief beasts, it is necessary to mention polynoodontic beasts that are very similar to them, have a high degree of differentiation, and are called "Mesozoic rodents".
Their molars have many rows of small tips (or small tumors), and the jaw has the characteristics of moving upwards and backwards when chewing, which are very different from the molars and lateral movements of other mammals with three tips, so they are often classified together as allotheria, and the Greek word "Allo-" in this word also means "different", representing the uniqueness of this type of mammal, so it is translated as "xenomorph".
Comparison of thief beasts, polynoodonts, and mammals with grinded wedge teeth
For mammals of the geological period, due to the limitations of fossil preservation, it is impossible to identify them with the characteristics of living mammals such as whether they have lactation behavior, efficient respiratory and circulatory system, and constant body temperature. In most cases, it is also uncertain whether the body surface has hair cover. Paleontologists generally define what a mammal is in terms of phylogeny, and the mammal thus defines the origin of mammals and the time of differentiation of major branches.
The origin of mammals is an important scientific issue in evolutionary biology and a long-standing hot topic of debate in academia. One of the important significance of the study of thief beasts and even exotic beasts is that they have greatly influenced the definition of mammals, the determination of the time of origin differentiation, and the interpretation of evolutionary patterns.
Today, the two dominant ideas diverged greatly in the development and origin of mammals, focusing on the systematic taxonomic position of the thief taxonomy. One study suggests that thief beasts were mammals outside the mammalian crown, while true mammals evolved in an explosive form during the early Middle Jurassic (about 160 million years ago).
Another study suggests that thief and polyodonts form sister groups, both belonging to mammals, because the earliest fossils of thieves, found in the Late Triassic, mammals appeared in explosive evolutionary radiation in the late Triassic period (about 280 million years ago). The biggest divergence between these two concepts remains in the understanding of the morphology of the thief beast.
Two mammalian phylogeny and origin time study hypotheses
Since the discovery of the first specimen in 2013, a total of six genera and eight species of thief beasts have been reported, all of which have preserved relatively well-preserved skeletal specimens, which has greatly increased the diversity of taxa and filled in many gaps in the morphology and evolution of thief beasts.
Although there are still some primitive features, they exhibit more mammalian features, such as the typical mammalian middle ear structure and the dental bone-temporal jaw joint; the teeth have typical mammalian amphilare, stable teeth and highly differentiated teeth that can bite precisely; and the clearly differentiated thoracolumbar spine and sternum, ribs prove that the diaphragm develops in the chest cavity that allows the animal to breathe in rapid motion.
The Jizantang odd beast's teeth bite and chew and move in three dimensions
These specimens also unveiled the biological features of this group of populations inhabiting the Jurassic forest in the Yanliao biota, their slender bones and elongated bones of the front and back limbs, reflecting a dexterous and lightweight basic structure; their hands and feet, with short metacarpal bones and very long finger (toe) bones, reflecting the skeletal characteristics of grasping and climbing; long tails, which can be wrapped around, are also characteristics of arboreal mammals. Not to mention, some taxa have leather wings between the anterior and posterior limbs, necks, and tails, with regularly arranged hairs on the wings, long and spreadable, plus a tail with hairs, for use as a motor balance.
This shows that in the Jurassic Forest, a group of elf-like mammals are doing experiments on the evolution of the ability to adapt to gliding, which is very similar to that of living gliding mammals. In addition, like many Mesozoic mammals, they had similar stingers to platypus on their feet; their skulls, jaws, teeth, and chewing methods indicate that their diet was dominated by insects, nuts, and fruits, while the heterogeneous development of teeth and the complication of the tip of the teeth of some genera reflected the change in feeding habits.
Aho's tree thief beast has well-preserved wings and hair
Although they are called "thieves", they are actually cute thieves, similar to modern honey bag shrews, very elf appearance (although the largest thief beast is estimated to weigh nearly a pound, but who said fat can not be a baby!). ）。 Therefore, thief, perhaps very clever, thief spirit thief meaning. In recent years, scientists have used mythical beasts, immortal beasts, strange beasts, etc. to name some of the thieves and beasts found in China. Nature is magical. Thieves are magical, and it is also a kind of fun.
The living honey bag shrew glids
Source: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences
Warm tips: Recently, the WeChat public account information flow has been revised. Each user can set up read-free subscription numbers, which will be displayed in the form of large cards. Therefore, if you do not want to miss the article of "Voice of the Chinese Academy of Sciences", you must do the following operation: Enter the "Voice of the Chinese Academy of Sciences" public number → click on the ··· Menu → Select "Set as Star"