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Many non-placental eutherians are thought to have been insectivores, as is the case with many primitive mammals. [41] However, the zhelestids are thought to have been herbivorous. [ 40 ] Body size of eutherians was generally small during the Cretaceous period, but the range of body sizes increased dramatically after the K-Pg extinction ...
Placental mammals (infraclass Placentalia / p l æ s ə n ˈ t eɪ l i ə /) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguished from monotremes and marsupials in that the fetus is carried in the ...
The mammalian male reproductive system contains two main divisions, the penis and the testicles, the latter of which are where sperm are produced and usually held in a scrotum. [5] In humans, both of these organs are outside the abdominal cavity , but they can be primarily housed within the abdomen in other animals.
The latter subclass is divided into two infraclasses: pouched mammals (metatherians or marsupials), and placental mammals (eutherians, for which see List of placental mammals). Classification updated from Wilson and Reeder's "Mammal Species of the World: A Taxonomic and Geographic Reference" using the "Planet Mammifères" website. [1]
The class Mammalia is divided into two subclasses based on reproductive techniques: monotremes, which lay eggs, and therians, mammals which give live birth, which has two infraclasses: marsupials/metatherians and placentals/eutherians. See List of monotremes and marsupials, and for the clades and families, see Mammal classification ...
Theria (/ ˈ θ ɪər i ə / or / ˈ θ ɛr i ə /; from Ancient Greek θηρίον (thēríon) 'wild beast') is a subclass of mammals [2] amongst the Theriiformes.Theria includes the eutherians (including the placentals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes and various extinct mammals evolving prior to the common ancestor of placentals and ...
Reproductive tract infection (RTI) are infections that affect the reproductive tract, which is part of the reproductive system.For females, reproductive tract infections can affect the upper reproductive tract (fallopian tubes, ovary and uterus) and the lower reproductive tract (vagina, cervix and vulva); for males these infections affect the penis, testicles, urethra or the vas deferens.
Marsupials have a separate genital tract, whereas most placental females have separate openings for reproduction (the vagina), urination (the urethra), and defecation (the anus). In monotremes, only semen passes through the penis while urine is excreted through the male's cloaca. [ 21 ]