Emergence of the Animal Kingdom
Or “Rise of the Chordates”
notochord - support
pharyngeal gill slits
dorsal hollow nerve cord
Gills in Humans! – check it out
sponge like - filter feeder
larva free swimming, bilateral with all Chordate traits
Lancets (a primitive fish like organism) closely resembles the idealized chordate.
The notochord, dorsal nerve cord, numerous gill slits, and post-anal tail all persist in the adult
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
“Ontogency Recapituates Evolution” Evolution Playing out in Fetus… (all these Chordates (birds, mammals, reptiles, fish, have strikingly similar Embryonic Development)
Definition of a Mammal:
Homoeothermic – meaning that mammals produce their own body heat
Mammary tissue - for the production of Milk
Hair Follicles - for the production of Hair
Generally, internal fertilization and harboring of young, however, this is only a generality because not all young are “cooked” to term internally.
eg. The Platypus, which has a BILL, lays EGGS, but still has mammary glands and produces MILK for young. This suggests a relationship between REPTILES, BIRDS and mammals. Imagine that?
– eg. The Kangaroo, which is a non-placental mammal. Here, the development of the young is very complex, and a baby kangaroo is born very “uncooked”, and must crawl into the mother’s pouch and latch onto a nipple to receive milk to continue development. You might say, baby Kangaroos or “Joey’s” get a womb with a view