a shelled egg, with a large yolk and a number of shell membranes, which retains water and allows reptiles, birds, and egg-laying mammals to reproduce on land. Named for the amnion, the innermost shell [..]

describes plants that can keep their internal water content constant, regardless of the external environment e.g. ferns, conifers and other gymnosperms, flowering plants.

a term describing a group of taxa (e.g. species, families) which are placed in the same taxonomic group but do not all have the same common ancestor e.g. the taxon consisting of the algae is polyphyle [..]

an animal that walks on all four feet.

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an extinct group of cartilaginous fish that first appeared in the Silurian period. Also called "spiny sharks" because they had a shark-like shape and numerous spines on their bodies and fins [..]

the evolutionary diversification of an ancestral population into several descendant populations, each adapted to a different ecological niche.

the process whereby food molecules are oxidised to produce CO2, H2O, and energy (in the form of the molecule ATP). Aerobic respiration requires oxygen and occurs in the mitochondria of all eukaryote c [..]

the "jawless fishes", a group that includes the modern hagfish and lamphrey. As their name suggests, they have no jaws. The skeleton is cartilaginous and they have no paired pectoral or pelv [..]