Marine Ecology- Prehistoric Oceans

Alexander Oparin

first to hypothesize that energy from lightning, volcanoes, and intense UV light created the first organic molecules from inorganic molecules. this has been proven true in many experiments since 1953

biological evolution

the change in a population's genetic makeup through successive generations

microevolution

describes the small genetic changes that occur in a population

macroevolution

describes long term, large-scale evolutionary changes among a group of species

adaptation

aka adaptive trait. genetically based traits that cause them to better survive and produce offspring

selective pressure

a factor in a population's environment that causes natural selection to occur

directional natural selection

causes allele frequencies to shift toward one end of the normal range, eliminating the other end

stabilizing natural selection

causes allele frequencies to shift toward the middle of the normal range, eliminating both ends

diversifying natural selection

causes allele frequencies to shift towards both ends, eliminating the middle

background extinction

the extinction of species at a low rate (1-10 species per year)

mass extinction

an abrupt rise in extinction rates about the background level

largest mass extinction

Permian - 250 million years ago. disappearance of 90% of marine species

last mass extinction

Cretaceous - 65 million years ago. marked the end of dinosaurs

paleontology

the study of fossils to learn about the earth's history

index fossils

found exclusively in rock layers of a particular geologic age (ex: Trilobites are 245-570 million years old)

Precambrian

4.6 BYA- 570 MYA

4.6 BYA

the Earth was formed. early atmosphere was water vapor, carbon dioxide, and nitrogen

4.2 BYA

ocean formed as the planet cooled and water vapor condensed

3.6 BYA

the first evidence of life, cyanobacteria

2.5 BYA

oxygen began to accumulate n the atmosphere

Paleozoic

570 MYA - 248 MYA

490 MYA

brachiopods, cephalopods, and trilobites dominate

443 MYA- 354 MYA

the Devonian Period aka "Age of Fishes"

250 MYA

large scale climatic changes led to the Permian extinction, wiping out 90% of marine species

Mesozoic

248 MYA - 65 MYA

aka the "Age of Reptiles" because dinosaurs dominated the land

200 MYA

Pangea breaks up and continents begin to move to their current locations

65 MYA

the Mesozoic ended with the Cretaceous extinction event. it was caused by a large asteroid hit off the Yucatan Peninsula in the Gulf of Mexico

Cenozoic

65 MYA - present

aka "Age of Mammals"

50 MYA

the first marine mammals appear, evolving from the land mammal Ambulocetus

2.5 MYA

humans evolved, with modern Homo sapiens appearing 250,000 years ago.

Coelacanth

A "living fossil" fish rediscovered in 1998, grows over 2 meters long, has hollow spine fins; only two extant species remain.

Atlantic Horseshoe Crab

Ancient arthropod more closely related to spiders than crabs; evolved 250–500 million years ago; has blue blood due to hemocyanin.

Megalodon

Prehistoric shark up to 60 feet long, one of the most powerful predators in history; related to the great white shark.

Trilobite

Paleozoic arthropod with 20,000+ species; important in the development of punctuated equilibrium; dominant in early oceans.

Nautilus

"Living fossil" cephalopod with an external shell, unchanged for ~500 million years; closely related to squid and octopus.

Plesiosaur

Prehistoric marine reptile (not a dinosaur) with paddle-like flippers; lived in shallow seas during the age of dinosaurs; species ranged 2–20 meters.

Helicoprion

Prehistoric shark with unique buzzsaw-like tooth whorls, likely located in the throat; poor fossil record due to cartilage skeleton.

Mosasaurus

Enormous aquatic lizard of the late Cretaceous, over 50 feet long with a streamlined skull, barrel-like trunk, and powerful tail.

Fossil

Preserved remains, impressions, or traces of organisms that provide evidence for past climates, geologic events, and evolution.

Extinction

The complete disappearance of a species, often shaping biodiversity and opening niches for new organisms.

Natural Selection

Process by which individuals with advantageous traits survive and reproduce more successfully, driving evolution.

Pangaea

A supercontinent that existed during the late Paleozoic and early Mesozoic eras before breaking apart into today’s continents.

Chemical Evolution

The theory that life originated from nonliving chemical compounds through natural processes.

Eras

Major divisions of geologic time (Precambrian, Paleozoic, Mesozoic, Cenozoic), each marked by distinct events and life forms.

Vestigial Structure

A structure that has lost its original function through evolution (e.g., whale hip bones).

Age of Fishes

The Devonian Period, when fish rapidly diversified and dominated the oceans.

Age of Mammals

The Cenozoic Era, when mammals rose to dominance after the extinction of the dinosaurs.