Ch.19 The Evolution of Vertebrate Diversity

WHAT ARE CHONDRICHTHYANS?

Sharks and rays have a flexible skeleton made of cartilage

Most sharks are fast-swimming predators, with sharp vision and a keen sense of smell

Electrosensors on their heads and a lateral line system aid them in locating prey

Most rays are adapted for life on the bottom, with dorsoventrally flattened bodies and eyes on the top of their heads

WHAT ARE THE FEATURES OF BIRDS FROM REPTILES?

Birds are reptiles with feathered wings, endothermic metabolism, and a number of adaptations for flight

–Loss of teeth

–Tail supported by only a few small vertebrae

–Feathers with hollow shafts

–Strong but light honeycombed bones

Flight is very costly, and birds are endotherms with a high rate of metabolism

Birds have relatively large brains and display complex behaviors

WHAT FOUR GROUPS OF APES DO HOMINOIDS INCLUDE?

Orangutans are shy and solitary and live in rainforest trees and the forest floor. Gorillas are the largest of the apes and are fully terrestrial. Chimpanzees make and use tools. Humans and chimpanzees diverged from a common ancestor between 5 and 7 million years ago. They share 99% of their genes. The other group is human.

SUMMARY:

Jawed vertebrates with gills and paired fins include sharks, ray finned fishes, and lobe finned fishes. The three lineages of jawed fishes are class chondrichthyes includes sharks and rays, ray-finned fishes and lobe-finshave lungs or lung derivatives, and lobe-finned fishes have muscular fins supported by stout bones. Ray finned fishes have internal skeleton reinforced with a hard matrix of CaPO3, flattened scales covered with mucus, operculum to move water over the gills, and buoyant swim bladder. Lobe fins have muscular pelvic and pectoral fins, supported by rod shaped bones. New fossil discoveries are filling in the gaps of tetrapod evolution. Amphibians include frogs, salamanders and caecilians. Reptiles and mammals are amniotes. The major derived character of this clade is an amniotic egg with an amnion, a private pond in which the embryo develops. Living birds evolved from a lineage of birds that survived the Cretaceous extinctions. Mammalians generally have larger relative brain size than other vertebrates and a relatively long period of parental care. Humans have the biggest brain among all the living things. There are three main types of mammals; eutherians, marsupials, and monotremes. The human story begins with our primate heritage from monkeys. Apes have relatively large brain size and flexible behavior. Gorillas, chimpanzees, and humans have a high degree of social organization. The oldest possible hominid yet discovered, Sakelanthropus tchadensis, lived about 7 to 6 million years ago. The fossil record suggests that hominid diversity increased dramatically between 4 to 2 million years ago.

KEY TERMS:

- tetrapods; jawed vertebrates with limbs and feet

- Amphibians: the first tetrapods able to move on land

- Birds: evolved from a lineage of small, two-legged dinosaurs called theropods

- Mammals: endothermic amniotes with hair, which insulates their bodies and mammary glands, which produce milk

- Monotremes: egg-laying mammals

- Placenta: structure that allows nutrients from the mother’s blood to diffuse into the embryo’s blood

- Marsupials: their offspring complete development attached to the mother’s nipples, usually inside a pouch or marsupium

- Tarsiers: second group of primates

- Anthropoid; group that includes monkeys, apes, and humans

- Gibbons: the only fully arboreal apes

A Homo Sapiens is one of a group of subspecies of Modern Humans, including human beings. The name of Homo Sapiens is wise, or wise man. They are bipedal (walking on two legs) Their backs are straight, not bent (Standing like this may have made tool carrying and tool-use easier.) They have a highly developed brain, which allows for language use

 

 

5 FACTS:

1)    A phylogenetic tree for chordates is based on a sequence of derived chracters.

2)    Birds are feathered reptiles with adaptations for flight.

3)    Mammals are amniotes that have hair and produce milk.

4)    The hominid branch of the primate tree is only a few million years old.

5)    Larger brains mark the evolution of HOMO.