Fissipedia

dnaoodb: professional biology database , biology encyclopedia

in biology, Fissipedia (Alias:Schizopoda) Carnivores that are usually mainly terrestrial are listed in the suborder Fissipedia, those that live in the sea are listed in the suborder Pinnipedia, and those that live in the sea are listed in the canine-like suborder Caniformes (bear-shaped suborders). order) or canine superfamily (ursinoid superfamily). Carnivora is the fourth largest order of mammals and one of the most familiar orders.

Some members of the order Carnivora are at the top of the food chain and their importance is irreplaceable. However, due to human activities, almost all top carnivores are endangered, and many small carnivores are also under certain threats. Members of the order Carnivora are not exclusively carnivorous, but there are also members that are omnivorous or even mainly plant-eating. They adapt to different living environments from the ocean to land, and are distributed almost all over the world. The main characteristic of Carnivora is that they have cleft teeth (meat teeth). The cleft teeth are composed of the last premolar of the upper jaw and the first molar of the lower jaw. Carnivora has appeared as early as the Paleocene Epoch, is rich in fossils, and includes some of the most familiar prehistoric creatures.

New Latin, from schiz- + -poda

Carnivores refer to eutherians or placental subclasses that mainly prey on warm-blooded animals, including two major categories of mammals that live in water and on land. By the latter part of the last century, people knew a lot about carnivores. Its morphological characteristics are mainly a pair of cleft teeth with cutting function formed by the upper fourth premolar and the first lower molar. The canine teeth are thick, the sagittal crest on the skull is high, the temporal fossa and the coronoid process of the mandible are large to accommodate the strong teeth. Temporalis muscle, with bony ear vesicle, low mandibular articular process, flexible limbs, separation of ulna and calvarius, scaphoid, lunate and capitate bones in the carpus are often healed, 4 or 5 toes, with sharp claws at the end. The classification above the family level is mainly based on the structure at the base of the skull, especially around the ear area.

In the 19th century, people used to divide land carnivores into two superfamilies represented by dogs and cats. The former includes bears, raccoons and mustelidae in addition to canidae, while the latter includes civets and hyenas in addition to cats. The abdominal wall of the former ear vesicle is composed only of the inner tympanic bone, and most of them have a pterygoid sphenoid canal; the latter otic vesicle is enlarged and divided into two chambers, and the abdominal wall is composed of two inner and outer tympanic bones, without a pterygoid sphenoid canal.

The discovery and in-depth research of new fossil materials in the 20th century have revised and supplemented the above classification. First, a superfamily, Miacoidea, was added. Such animals are found in the Paleocene and Eocene of the Holarctic. Although they have true cleft teeth, they are still primitive in other respects. The bodies are small, the ear vesicles have not yet ossified, the premolars have not degenerated, the molars are still wedge-shaped, and there is no healing in the wrist bones.

Secondly, it was found that the canidae are far away from bears, raccoons and mustelids in terms of systematic relationship, but closer to cats. This has been confirmed by both ear anatomy and serum studies. Therefore, terrestrial carnivores can be divided into two major taxa: bears and dogs and cats. Aquatic carnivores have extremely specialized shapes, with streamlined bodies, paddle-shaped limbs, and homogeneous teeth that tend to disappear. At first, people put them in a separate order, but more facts show that they are a branch of terrestrial carnivores that returned to the water. Some people classify them and terrestrial carnivores into two suborders based on their morphology: the aquatic Pinnepedia and the terrestrial Fissipedia. However, some people group eared seals (Otariidae) and walruses (Odobenidae) with raccoons and bears based on cladistics, while earless seals (Phocidae) are grouped with musteas.

The classification of Carnivora at the family level is less controversial. The biggest disagreement is about the classification position of giant pandas. Some people think it is closer to bears. Some people put it together with the red panda, which was originally classified into the raccoon family, to establish the panda family (Ailuridae). Some people also establish a separate family (Ailuropodidae) for giant pandas. The primitive giant panda fossil recently discovered from the Lufeng Hominin site in China shows that it is still closer to the bear family. The living species of the Panda family are limited to the northern part of the Oriental Realm, and the earliest fossils were found in the Upper Pliocene of the Holarctic Realm. China has discovered quite a lot of fossils from the Upper Pliocene to the Middle Pleistocene.

Procyonidae

Living species are limited to the New World. This is a small to medium-sized animal. Their upper cleft teeth have larger primary and secondary cusps. The molars are mostly square or rectangular, with a semi-closed fossa on the external auditory canal. Fossils are found mainly in North America. First appeared in the Early Oligocene Epoch. Recently, some people have classified Pleisictic and others discovered in the European Oligocene into this family based on the structure of the ear region. No fossils of this family have been found in China so far.

Ursidae

Living species are distributed throughout the Arctic and South America. These are some heavy-bodied animals. Their cleft teeth become smaller, the premolars retract, the molars enlarge, the crown surface decoration is complex, the basal and occipital parts are short and wide, the ear vesicle is flat, and the external auditory canal is long. They probably originated from Cephalogale, the European Oligocene epoch. The main representative of the Late Tertiary is Ursavus. This genus has also been found in North America and China, and by the Pliocene Epoch modern genera have appeared. There are two branches of bears from the late Eocene to the Pliocene. One is Amphicyoninae. This type of animal is mainly found in continental Europe, with a few fossils also found in North America. This is a rather large animal whose tooth shape is very similar to that of canids, so it has long been classified as canine. Recently, it was discovered that the base structure of their skulls and the structure of their limbs are closer to those of bears, so they were reclassified to the Ursidae family. The other type is Hemicyoninae, whose geographical distribution is the same as that of dogs and bears. The early and middle Miocene are represented by Hemicgon, the late Miocene is represented by Indarctos, and the Pliocene is represented by Agriotherium. This is also a very large animal, and its teeth are quite close to those of bears.

Mustelidae

Living species are distributed on all continents except Oceania, Antarctica and some islands. These are small to medium sized animals. Their lobed teeth are not large, and the lobes do not have deep central concavities. The inner half of the upper first molar is enlarged, and its length is always longer than the outer edge. The third molar is recessed, and the upper and lower second molars are also very recessed. . The Mustelidae family is highly morphologically diverse and has a complex developmental history. There are subfamilies such as Lutrinae, Mustelinae, Mellivorinae, Mephitinae, Melinae, and Leptaretinae. Fossils of mustelids are found throughout the world. It was first discovered in the Oligocene Epoch and flourished from the Miocene to modern times.

Canidae

The geographical distribution of extant species is roughly the same as that of the Mustelidae. They are medium in size and are hunting type. The skull is low and long, with complete teeth and only missing teeth. Its evolutionary backbone is in North America, beginning in the Oligocene. In the Old World, they only began to appear at the end of the Miocene, mainly raccoon dogs (Nctereutes) and dogs (Canis), which apparently migrated from North America through the Bering Land Bridge.

Felidae

The distribution of extant species is the same as above. The body size ranges from small to large, belonging to the leaping type. The skull is short and round, with particularly developed lobes and lobes. The canine teeth are thick or very long and flat, and other cheek teeth are degenerated. The ear bubble is round and swollen, divided into two chambers, and the claws are particularly sharp and retractable. Early specialized hunting cats (Nimravinae) appeared in North America at the end of the Early Eocene. Their tooth pattern is less degenerated. The upper cleft teeth retain a large proto-cusp, but the lower posterior tip of the lower cleft teeth disappears. This type of animal became extinct by the late Miocene. The European continental Metailurus may be its descendant. The other branch is the false saber-tooth cat (Hoplophoneinae). Their upper canines have become saber-shaped, and their mandibular symphysis has downward-extending leaf-like protrusions. This type of animal began in the Oligocene Epoch and is distributed throughout the world. True saber-toothed cats appeared in the late Miocene and were finally extinct in North America in the late Pleistocene. Cats in the narrow sense probably evolved from Proaelurus in Europe's Oligocene Epoch through Pseudaelurus. Fossils of false cats and later true cats have also been found in North America.

Viverridae

Living species are found only in Africa and the southern half of the Palearctic. This is a small to medium-sized animal. The skull shape and teeth are closer to those of canids, but the proto-apex of the upper cleft tooth is larger and has a more developed anterior appendage cusp. Marked fur and glandular development are also characteristics of this animal. The earliest civets were discovered in the Upper Eocene of Europe. Since the late Oligocene, it has been divided into two branches: civet and civet.

Hyaenidae

The living representatives are larger hunting and scavenging animals and a type of specialized anteaters, which are only distributed in Africa and southern Asia. The teeth of ant-eating hyenas (Proteles) are extremely degraded, while hyenas in the narrow sense have thick conical premolars, cleft teeth are developed, and molars are degraded. Its evolutionary backbone is in the Palearctic and Africa. In the middle Miocene, there was an early specialized hyena (Percrocuta). There were many types of hyenas in the late Miocene, and the fossils were also abundant, especially the ferret hyenas (Ictitheriinae). Living genera appeared in the Pliocene, and one of them, the leopard hyena (Chasmaporthetes), entered North America through the Bering Land Bridge.