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What else can I help you with?
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.
Do amphibians have highly developed brains?
Yes, amphibians have highly developed brains.
What is a placenta formed from?
The placenta is developed during pregnancy from the implantation of a blastocyst. The blastocyst creates the outer layer of the placenta. This continues to developed into two more portions and then develops an outer protective layer. The placenta grows throughout the entire pregnancy.
Why have Amphibians become extinct?
On what planet? Amphibians are alive and well on Earth.
Pangaea was in existence and invertebrates and amphibians were common?
When Pangaea was in existence, the main animals were reptiles and amphibians. During this time, birds developed also.
What was developed first amphibians or mammals?
Amphibians. Amphibians evolved in the Devonian period, about 400 mya. Adelobasileus, thought to be the ancestor of all modern mammals, lived in the late Triassic, about 225 mya.
Are dinosaurs more closely related to amphibians than reptiles?
Dinosaurs are more closely related to reptiles than to amphibians. In fact, dinosaurs are classified as reptiles. Amphibians are lower on the evolutionary tree than reptiles. Reptiles developed from amphibians. Amphibians developed from fish.
What is the mammalian group that lacks a placenta?
Fish, birds, crocodiles, insects, lizards, amphibians, and pretty much anything that isn't a mammal or gives live birth.
How are amphibians different from repetiles?
Reptiles live on dry land; amphibians live on land as well as in water.
How do you make amphibians?
Nobody alive today is "making amphibians". According to scientists, amphibians developed at some point in the Devonian Era, between 400-350 million years ago from fishes through gradual changes. According to creationists, God created amphibians.
What do amphibians have that bony fish do not?
Well they have limbs and lungs, which I would consider more complex.
When fish first walked?
The first fish to develop legs and who mostly developed as the earliest amphibians, being able to live on and as well in water, came about around 370-400 million years ago.
