Biology Chapter 26

What does fossil evidence indicate about early animals?

Multicellular life appeared around 600 MYA; most were tiny and soft-bodied, so few fossilized.

What are trace fossils?

Tracks and burrows left by animals whose bodies weren't fossilized.

What is the Ediacaran Fauna?

Fossils from 565-544 MYA found in Australia; resemble jellyfish and worms.

What was the Cambrian Explosion?

A period of rapid evolution where complex body plans appeared.

What major features developed during the Cambrian Explosion?

Specialized cells/tissues, body symmetry, segmentation, appendages.

What do cladograms of invertebrates show?

Evolutionary relationships and the sequence of major evolutionary events.

Which phyla are included in invertebrates?

Porifera, Cnidaria, Arthropoda, Nematoda, Platyhelminthes, Annelida, Mollusca, Echinodermata.

What key features are observed in invertebrates?

Body symmetry, cephalization, segmentation, coelom formation.

What are the earliest chordates likely related to?

Echinoderms.

What features did early chordates have?

Paired muscles, cartilage, fins, gills, skull with sense organs.

What animals are modern chordates?

Lancelets, tunicates, fishes, amphibians, reptiles, birds, mammals.

What is an example of an early chordate?

Pikaia.

What are characteristics of jawless fishes (Class Agnatha)?

No vertebrae, notochords as adults; ex: lampreys, hagfish.

What are characteristics of cartilaginous fishes (Class Chondrichthyes)?

Paired fins, cartilage skeletons; ex: sharks, rays.

What are characteristics of bony fishes (Class Osteichthyes)?

Hard, calcium-based skeletons; ray-finned; ex: eels, catfish.

What are characteristics of lobe-finned fishes?

Fleshy, bony fins; evolved into tetrapods; ex: lungfish, coelacanth.

What are general fish traits?

Ectothermic, external fertilization, lay eggs, separate sexes.

What does Amphibia mean?

"Double life"; water as larvae, land as adults.

What are characteristics of amphibians?

Moist skin, no claws/scales, ectothermic, 3-chambered heart, external fertilization.

What are the orders of amphibians?

Anura (frogs), Caudata (salamanders), Gymnophiona (caecilians).

What are characteristics of reptiles?

Dry scales, lungs, limbs, shelled eggs, 3-chambered heart (except crocodilians), ectothermic.

What are the orders of reptiles?

Squamata, Crocodilia, Testudinia, Sphenodontia.

What are characteristics of birds (Class Aves)?

Endothermic, feathers, wings, scaled legs, lightweight bones, internal fertilization, lay eggs.

What was the first birdlike fossil?

Archaeopteryx; 150 MYA, Jurassic Period.

What are characteristics of mammals (Class Mammalia)?

Mammary glands, hair, 4-chambered heart, endothermic.

What are the three major groups of mammals?

Monotremes (egg-layers), marsupials (pouch), placentals (internal development).

What are characteristics of primates?

Long fingers/toes, nails, rotating arms, strong clavicle, binocular vision, large cerebrum.

What are lemurs and lorises?

Small, nocturnal primates with large eyes and long snouts.

Where are lemurs and lorises found?

Bush babies in Africa, lemurs in Madagascar, lorises in Asia.

What are tarsiers and anthropoids?

Humanlike primates with broad faces and wide nostrils.

Where are New World monkeys found?

Central and South America.

What are characteristics of New World monkeys?

Long, flexible arms, prehensile tail; ex: squirrel monkeys, spider monkeys.

What are hominines?

Humans and species more closely related to humans than chimps.

What are key traits of hominines?

Bipedalism, aligned skeleton for upright walking, opposable thumbs, large brains.

What are examples of early Homo species?

Homo habilis, H. ergaster, H. rudolfensis, H. neanderthalensis, H. sapiens.