Tag: classifications of chordata

Unidirectional flow means that air moving through bird lungs is largely 'fresh' air & has a higher oxygen content.  So, in bird lungs, more oxygen is available to diffuse into the blood. 

Maternal nutrition plays a vital role in the growth and development of the fetus. During prenatal development, the fetal circulatory system is integrated with the placenta via the umbilical cord so that the fetus receives both oxygen and nutrients from the placenta. The placenta is an organ that develops in your uterus during pregnancy. This structure provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood. The placenta attaches to the wall of your uterus, and your baby's umbilical cord arises from it.

Metatherians or marsupials are mammals mostly found in Central and South America and in Australia. They include animals like bilbies, wombat, and kangaroos et cetera. In contrast to placental mammals, their scrotum develops in front of the penis instead of behind it. 

Snakes have leathery, soft or hard eggs laid on land or maintained inside the body until hatching. Salamanders have soft eggs normally laid in water or in damp media.

Marsupials have two vagina and two uterus and before birth a birth canal forms between them. The ancestors of marsupials are part of a larger group called metatherians and they represent the clade originating from the last common ancestor of metatherians. So, the correct option is 'Metatheria'.

• Baboon is an old world monkey belonging to the genus Papio
• Baboon is a very strong animal having sharp canine teeth
• They are well known for their intelligence

Metatherians are mammals that are also known as marsupials. Most of the marsupials are found in Central and South America and in Australia. They are called marsupials as they have a marsupium or pouch on their bodies. This group consists of animals like kangaroos, wombat, macropods, et cetera.

• Oviparous animals are the egg-laying animals which show little or no embryonic development within the mother.
• This type of reproductive method is common in most fish, amphibians, reptiles, birds and prototherians.
  
• Prototherians are egg-laying mammals and feed their newborn like all other mammals.  
• They lack nipples but the skin over their mammary glands secrete milk for their babies. 
• They are called monotreme as they have only one opening for excretion and reproduction. 
• So, the correct answer is 'Prototheria'.

Gorillas are ground-dwelling, herbivorous apes, they are the largest living primates, which are mammalian animals.