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Why are monotremes found in austrillia?
Monotremes were among the earliest mammals to evolve. However, in most of the world, all monotremes went extinct as a result of competition with more advanced placental mammals. Australia and New Guinea, however, have been so isolated that there were nearly no placental mammals (except for bats) until humans introduced them. The lack of competition from placental mammals allowed monotremes to survive in Australia.
What organ do pregnant monotremes and marsupials lack?
A complex placenta. Marsupials have a choriovitelline placenta, but it is not as well-developed as the placentas of placental mammals.
What is the Order Edentata?
Edentata (meaning toothless, because the members do not have front incisor teeth or molars, or have poorly-developed molars) is an outdated classification: It mistakenly grouped anteaters, sloths, armadillos, ground sloths, glyptodonts ,pampatheres together with the pangolins and aardvarks. It was subsequently realized that Edentata contained unrelated families and was thus invalid by cladistic standards.
Which is the difference between the three mammal groups?
The three main groups of mammals are monotremes, marsupials, and placental mammals. Monotremes, like the platypus, lay eggs and produce milk but lack nipples. Marsupials, such as kangaroos, give birth to underdeveloped young that continue to develop in a pouch. In contrast, placental mammals, including humans, have a complex placenta that nourishes the developing fetus during a longer gestation period inside the womb.
Why are some mammals that lay eggs classified as mammals?
Monotremes lay eggs, as do reptiles. Monotremes' limbs go outward (rather than downward) from their main body, which is also true for reptiles. Monotremes lack a corpus callosum (which placental mammals have), as do reptiles. Monotremes and reptiles both have cloacas, while placental mammals have separate openings for urination and defecation. This evidence all shows monotremes to be a link between reptiles and mammals, but we now think that monotremes just evolved from an earlier branching from the mammalian tree of lineage than the marsupials and placental mammals evolved from. Monotremes are not a link between reptiles and mammals.
What are the main features of a placental mammal?
The primary feature is a fully developed placenta in females in which the babies are nurtured before birth. Other features that placental mammals have that other mammals do not have include the lack of epipubic bones, a wide opening at the bottom of the pelvis, a malleolus at the bottom of both the tibia and the fibula, and a ball-and-socket upper ankle joint (the ankle forms the socket, the tibia and fibula form the ball).
What are toothless mammals called?
Toothless mammals are called edentates. This group includes species such as anteaters, sloths, and armadillos. Edentates are characterized by their lack of teeth or reduced dentition, which is an adaptation to their specific diets and lifestyles.
Why are marsupials primitive mammals?
A misnomer posed by some earlier poster is that it is like a reptile. The correct answer is, it is not considered the most primitive mammal. This was incorrectly presumed by 19th century scientists. It is actually uniquely evolved. If you're attempting to find out the most primitive "modern" mammals, they could be argued to be the Soricidae, the shrews and the Talpidae, the moles, but any modern creature is simply not primitive. More basic, more complex, more or less evolutionary divergent from their ancestral norms, but not more primitive.
Do a burrowing owl have sharp teeth?
No, burrowing owls do not have sharp teeth. Like all birds, they lack teeth altogether; instead, they have a beak that is adapted for their dietary needs. Burrowing owls primarily feed on insects, small mammals, and other small prey, using their beaks to catch and consume food.
Why mammals suffer from lack of oxygen?
Respiration of mammals is aerobic.So O2 is essential for living.
Do monotrems have mammary glands?
Yes. Monotremes are mammals, so they have mammary glands. What they lack, however, is developed teats for the young babies to suckle. These animals do not suckle their young quite like other mammals do. They do not have nipples, but exude milk from specialised sweat glands on their abdomen.
What was queen Elizabeth's teeth like?
Despite what movie makers portray there are account that her teeth like may of her couriers were blackened with decay and generally yellow. This was general across the range of people of the time due to a lack of understanding about oral hygiene and maintenance.
