HOME
TheInfoList



Postdentary Trough
The postdentary trough is a skeletal feature seen in Mesozoic mammals. It is found on the inside of the lower jaw (dentary), at the back behind the molar teeth. It is the hollow in which the postdentary bones and Meckel's cartilage sit. These bones form the middle ear in later mammal groups (see Evolution of mammalian auditory ossicles), they include the incus (quadrate), malleus (articular), ectotympanic (angular) and prearticular.Zhe-Xi Luo 201Developmental patterns in Mesozoic evolution of mammal ears Annual Review of Ecology, Evolution, and Systematics, 42, 355-380 In Mesozoic mammals these bones gradually change position and size until they are incorporated in the middle ear. References Mammal anatomy Evolution of mammals {{Vertebrate anatomy-stub ...
[...More Info...]      
[...Related Items...]



picture info

Evolution Of Mammals
The evolution of mammals has passed through many stages since the first appearance of their synapsid ancestors in the Pennsylvanian sub-period of the late Carboniferous period. By the mid-Triassic, there were many synapsid species that looked like mammals. The lineage leading to today's mammals split up in the Jurassic; synapsids from this period include ''Dryolestes'', more closely related to extant placentals and marsupials than to monotremes, as well as ''Ambondro'', more closely related to monotremes. Later on, the eutherian and metatherian lineages separated; the metatherians are the animals more closely related to the marsupials, while the eutherians are those more closely related to the placentals. Since ''Juramaia'', the earliest known eutherian, lived 160 million years ago in the Jurassic, this divergence must have occurred in the same period. After the Cretaceous–Paleogene extinction event wiped out the non-avian dinosaurs (birds being the only surviving dinosaurs) an ...
[...More Info...]      
[...Related Items...]



picture info

Dentary
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone of the skull (discounting the ossicles of the middle ear). It is connected to the temporal bone by the temporomandibular joint. The bone is formed in the fetus from a fusion of the left and right mandibular prominences, and the point where these sides join, the mandibular symphysis, is still visible as a faint ridge in the midline. Like other symphyses in the body, this is a midline articulation where the bones are joined by fibrocartilage, but this articulation fuses together in early childhood.Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, p. 59 The word "mandible" derives from the Latin word ''mandibula'', "jawbone" (literally "one used for chewing"), from ''mandere'' "to chew" and ''-bula'' (instrument ...
[...More Info...]      
[...Related Items...]