The Formation of the Earth
The Earth’s initial atmosphere likely consisted of these gases, which were released by volcanic activity.
What are water vapor, carbon dioxide, and nitrogen?
The earliest forms of life on Earth were likely simple, single-celled organisms known as this.
What are prokaryotes?
Fossils, like those of trilobites and early fish, can be found in these types of rocks, which form from the compression of sediments over long periods of time.
What are sedimentary rocks?
This era, which began about 4.6 billion years ago, is divided into the Hadean, Archaean, and Proterozoic eons.
What is the Precambrian Era?
The emergence of this key trait in primates, which allows for grasping tree branches and handling food, is characterized by the presence of these digits.
What are opposable thumbs?
This lunar body is hypothesized to have formed after crashing into the Earth at the beginning.
What is the moon?
This theory suggests that life originated from simple organic compounds in a primordial soup, sparked by energy sources like lightning.
What is abiogenesis or synthetic genesis?
Exposure to this gas is likely to impede fossilization of remains as it increases decay
What is oxygen gas?
This geological period, which spanned from 541 to 485 million years ago, is known for the rapid diversification of marine life, marking the start of the Paleozoic Era.
What is the Cambrian Period?
The evolution of larger brains relative to body size is a notable feature in primates, especially in this group that includes humans, chimpanzees, and gorillas.
What are Great Apes?
This hypothesis describes that life was not originally from Earth, but rather somewhere outside of Earth.
What is the extraterrestrial hypothesis?
This process is thought to have occurred when certain prokaryotic cells engulfed others, leading to the formation of eukaryotic cells.
What is endosymbiosis?
This method of dating fossils is based on the decay of isotopes such as carbon-14 and is particularly useful for dating organic materials up to about 50,000 years old.
What is radiometric dating?
The rise of the first plants on land and the colonization of the terrestrial environment occurred during this period, part of the Paleozoic Era.
What is the Silurian Period?
This fossil species, dating to about 6-7 million years ago, is considered one of the earliest known ancestors of the human lineage and shows evidence of both bipedalism and climbing abilities.
What is Sahelanthropus tchadensis?
This hypothesis suggests that life on Earth could've originated from volcanic activity in deep oceans.
What is the Deep-Sea Hypothermal vents hypothesis?
This hypothesis proposes that the first living cells were likely simple, self-replicating molecules of this type, which can catalyze chemical reactions.
What are RNA molecules?
These fossils are created from autotrophic cyanobacteria and layered structures of calcium carbonate
What are stromatolites?
During this era, this group of reptiles, including the Tyrannosaurus rex and Brachiosaurus, dominated terrestrial ecosystems.
What is the Mesozoic Era?
This primate, thought to have lived between 10 and 7 million years ago, is one of the closest known ancestors to both humans and chimpanzees, with evidence of bipedalism and tree climbing.
What is Ardipithecus ramidus?
This experiment's goal was to recreate the early atmosphere of Earth, and is said to have recreated the "primordial soup" of an ancient Earth's ocean.
What is the Miller-Urey experiment?
The Miller-Urey experiment successfully demonstrated that organic molecules, such as these, could form under conditions mimicking early Earth’s atmosphere.
What are amino acids?
This fossilized organism famously depicts a transitional form between reptiles and birds.
What is Archeopteryx?
The first true mammals, such as the small, nocturnal creatures from the late Triassic period, appeared during this period of the Mesozoic Era.
What is the Triassic Period?
This early hominid, which lived around 4 million years ago, is famous for its partial bipedalism, long arms, and relatively small brain, and it was discovered in Ethiopia and has been affectionately referred to as "Lucy"
What is Australopithecus afarensis?