Major Extinction Events and Hominin Evolution Flashcards

Vocabulary flashcards covering the five major mass extinction events and key hominin species throughout Earth's evolutionary history.

Ordovician Extinction

The 1st major mass extinction (444 Mya, Paleozoic Era) caused by intense glaciation and sea-level drops; wiped out ~85% of marine species, heavily impacting brachiopods, trilobites, and conodonts.

Devonian Extinction

The 2nd major extinction (365 Mya, Paleozoic Era) that primarily affected marine ecosystems due to widespread ocean anoxia (oxygen depletion), possibly triggered by land plant expansion, and devastated reef builders.

Permian Extinction

Known as 'The Great Dying' (252 Mya, Paleozoic Era), the most severe mass extinction in Earth's history, eliminating ~96% of marine and 70% of terrestrial species, triggered by Siberian Traps volcanic activity and extreme global warming.

Triassic Extinction

The 4th major extinction (201 Mya, Mesozoic Era) caused by massive volcanic eruptions in the Central Atlantic Magmatic Province (CAMP), clearing ecological niches and paving the way for the dominance of the dinosaurs.

Cretaceous (K-Pg) Extinction

The 5th major extinction (66 Mya, Mesozoic Era) caused by a massive asteroid impact (Chicxulub) and Deccan Traps volcanism; famous for wiping out all non-avian dinosaurs, pterosaurs, and ammonites.

Sahelanthropus tchadensis

One of the oldest known hominin species (7 to 6 Mya, Miocene Epoch), discovered in Chad; exhibits a mix of ape-like and human-like features, with cranial evidence suggesting early facultative bipedalism.

Ardipithecus ramidus

Famously known as 'Ardi' (4.4 Mya, Pliocene Epoch); possessed a grasping big toe adapted for tree climbing alongside pelvic modifications that clearly indicate regular bipedal walking on the ground.

Australopithecus afarensis

Hominin lineage (3.9 to 2.9 Mya, Pliocene Epoch) that includes the famous 'Lucy' fossil; fully bipedal but retained adaptations for tree climbing, demonstrating that bipedalism evolved well before large brain sizes.

Homo habilis

Known as 'Handy Man' (2.4 to 1.4 Mya, Pleistocene Epoch); recognized as one of the earliest members of our genus and strongly associated with the systematic creation and use of Oldowan stone tools for scavenging meat.

Homo erectus

Hominin species (1.9 Mya to 110,000 Ya, Pleistocene) that was the first to achieve modern human body proportions and obligate bipedalism, migrate out of Africa, control fire, and craft complex Acheulean handaxes.

Homo neanderthalensis

Our closest extinct relatives (400,000 to 40,000 Ya, Pleistocene); robustly built for cold Eurasian climates, developed large brains, practiced intentional burial rituals, controlled fire, and interbred with Homo sapiens.

Homo sapiens

Anatomically modern humans (300,000 Ya to Present, Pleistocene/Holocene); characterized by high, rounded skulls, small faces, and a distinct chin, who developed advanced symbolic culture, complex tools, and rapid global dispersal.