Eutheria
Eutheria (Placentalia) An infraclass of mammals in which the embryos are retained in a uterus in the mother's body and nourished by a placenta. The young are thus fully protected during their embryonic development and kept at a constant temperature. Placental mammals evolved during the Cretaceous period (about 100 million years ago). Modern placentals are a highly diverse group that occupy all types of habitat in all parts of the world. They include the orders Artiodactyla, Carnivora, Cetacea, Chiroptera, Insectivora, Perissodactyla, Primates, Proboscidea, and Rodentia. Compare Metatheria; Prototheria.
Eutheria
Eutheria (class Mammalia, subclass Theria) The infraclass that includes all of the placental mammals and which probably arose during the Cretaceous. The blastocyst develops an outer layer of cells which surrounds a small inner group from which the embryo develops. This is retained in the uterus, nourished by means of an allantoic placenta, and born in an advanced stage of development. In adults there is no marsupium and the pelvic bones form an os innominatum. The tympanic bone may be ring-like or may form a bulla, but the alisphenoid bone never forms part of the bulla. There is no in-turned angle of the jaw.
Eutheria
Eutheria (class Mammalia, subclass Theria) The infraclass that includes all of the placental mammals, and which probably arose during the Cretaceous. The embryo is retained in the uterus, nourished by means of an allantoic placenta, and born in an advanced stage of development.
More From encyclopedia.com
Ossification , Ossification is the process of the synthesis of bone from cartilage. There are two types of ossification—intramembranous and endochondral ossificatio… Bone , bone Fairly early in the evolution of multicellular organisms it became an advantage to have a hard body component which could provide protection for… Osteopetrosis , Definition
Osteopetrosis (plural osteopetroses) is a rare inherited disorder that makes bones increase in both size (mass) and fragility. It is a pot… Musculoskeletal System , Skeletal System Overview (Morphology)
When death has occurred weeks or months before a body is discovered, decomposition removes much of the body flu… Skull , Skull
Definition
The skull—or cranium—is the skeleton of the head. It includes the brain case and the bones of the face and jaw.
Description
The skul… Bone Transplantation , Definition
Bone grafting is a surgical procedure by which new bone or a replacement material is placed into spaces between or around broken bone (fra…
About this article
Eutheria
All Sources -
You Might Also Like
NEARBY TERMS
Eutheria