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This is a collection of lists of mammal gestation period estimated by experts in their fields. The mammals included are only viviparous (marsupials and placentals) as some mammals, which are monotremes (including platypuses and echidnas) lay their eggs. A marsupial has a short gestation period, typically shorter than placental.
Marsupials have a short gestation period—typically between 12 and 33 days, [38] but as low as 10 days in the case of the stripe-faced dunnart and as long as 38 days for the long-nosed potoroo. [39] The baby (joey) is born in a fetal state, equivalent to an 8–12 week human fetus, blind, furless, and small in comparison to placental newborns ...
The duration of this period varies between species. For most species, the amount a fetus grows before birth determines the length of the gestation period. Smaller species normally have a shorter gestation period than larger animals. [2] For example, a cat's gestation normally takes 58–65 days while an elephant's takes nearly 2 years (21 ...
A marsupial has a short gestation period, typically shorter than its estrous cycle, and gives birth to an underdeveloped newborn that then undergoes further development; in many species, this takes place within a pouch-like sac, the marsupium, located in the front of the mother's abdomen.
Among mammals, marsupials and most rodents are altricial. Domestic cats, dogs, and primates, such as humans, are some of the best-known altricial organisms. [14] For example, newborn domestic cats cannot see, hear, maintain their own body temperature, or gag, and require external stimulation in order to defecate and urinate. [15]
Marsupials have a short gestation period, typically shorter than its estrous cycle and generally giving birth to a number of undeveloped newborns that then undergo further development; in many species, this takes place within a pouch-like sac, the marsupium, located in the front of the mother's abdomen.
A pregnant mongrel A feral dog from Sri Lanka nursing her puppies. Gestation in a dog is 63 days in length, if measured from the day of ovulation. Since it is difficult to determine the exact date of ovulation, errors are often made in calculating gestation period. [21]
Order Carnivora (carnivorans: dogs, cats, bears, pinnipeds, mongooses, raccoons, skunks, hyenas, weasels, etc.) The exact relationships among these three lineages is currently a subject of debate, and four different hypotheses have been proposed with respect to which group is basal or diverged first from other placentals.