Life and Evolution (Biodiversity, Fossils, and Transitions)

What were the major evolutionary events in Earth’s history?

Origin of life from organic molecules; Rise of multicellularity, sexual reproduction, biomineralization; Cambrian Explosion; Vertebrate evolution; Synapsid to mammal transition; Evolution of flowering plants.

What was the Cambrian Explosion?

Rapid diversification of life ~541 million years ago; appearance of most major animal phyla.

How did mammals evolve?

Evolved from synapsids in the Late Triassic; small, warm-blooded, likely nocturnal.

When did mammals evolve?

During the Late Triassic, alongside early dinosaurs.

What were key adaptations for mammal success?

Endothermy, hair, live birth (most), specialized teeth, large brains.

What was the diversity of Mesozoic mammals like?

Small insectivores, early herbivores and carnivores living in dinosaur-dominated environments.

What is the difference between Ornithischians and Saurischians?

Ornithischians = bird-hipped, herbivores; Saurischians = lizard-hipped, includes theropods and sauropods.

What are general traits of Theropods?

Bipedal carnivores like T. rex and Velociraptor; some had feathers and evolved into birds.

What are general traits of Ornithischians?

Herbivores with beaks, some had armor or horns (e.g., Triceratops, Stegosaurus).

What are general traits of Sauropodomorphs?

Long-necked, quadrupedal herbivores like Brachiosaurus and Diplodocus.

How do you distinguish a dinosaur from a non-dinosaur?

Dinosaurs had upright posture with legs under their bodies; specialized hip and ankle bones.

What fossils are found in Triassic red beds?

Amphibians, reptiles, early dinosaurs, therapsids, mollusks, fish, and plants.

What depositional environments created Triassic red beds?

Floodplains, alluvial fans, rivers—nonmarine, well-drained.

What fossils are found in the Zuni Sea?

Marine reptiles, ammonites, clams, fish, and coccolithophores (plankton).

What fossils are found in the Morrison Formation?

Abundant dinosaurs including sauropods, stegosaurs, theropods.

What’s found at Dinosaur National Monument?

155–148 million-year-old dinosaur fossils preserved in a sandbar deposit.

What types of fossils are found in Eocene to Miocene ash deposits?

Plants, rodents, early horses, camels, and primates; preserved by volcanic ash.

What fauna lived in the Oligocene?

Early horses, camels, oreodonts, saber-tooth relatives, and rodents.

When and where did the first whales evolve?

During the Eocene in South Asia (Pakistan/India).

What did whales look like in the Eocene?

Early whales like Pakicetus had four limbs; transitional forms like Basilosaurus had small hind limbs and long bodies.

What is megafauna?

Large-bodied animals (typically over 100 lbs) from the Pleistocene and earlier.

What are examples of megafauna from different continents?

North America: mammoths, saber-tooths; South America: giant sloths; Australia: diprotodon; Europe: woolly rhinos; Africa: giant antelope