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Models of food-sharing are based upon general evolutionary theory. When applied to human behavior, these models are considered a branch of human behavioral ecology. Researchers have developed several types of food-sharing models, involving phenomena such as kin selection, reciprocal altruism, tolerated theft, group cooperation, and costly ...
Solitary life in animals is considered to be the ancestral state of living; and group living has thus evolved independently in many species of animals. [2] Therefore, species that form groups through social interaction will result in a group of individuals that gain an evolutionary advantage, such as increased protection against predators ...
This innovation causes a major burst of animal coevolution. First freshwater pelomedusid turtles. Earliest krill. 120 Ma Oldest fossils of heterokonts, including both marine diatoms and silicoflagellates. 115 Ma First monotreme mammals. 114 Ma Earliest bees. [94] 112 Ma Xiphactinus, a large predatory fish, appears in the fossil record. 110 Ma
The evolution of the molluscs is the way in which the Mollusca, one of the largest groups of invertebrate animals, evolved. This phylum includes gastropods , bivalves , scaphopods , cephalopods , and several other groups.
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
Fish may have evolved from an animal similar to a coral-like sea squirt (a tunicate), whose larvae resemble early fish in important ways. The first ancestors of fish may have kept the larval form into adulthood , as some sea squirts do today, although this path cannot be proven.
In evolution, cooperation is the process where groups of organisms work or act together for common or mutual benefits. It is commonly defined as any adaptation that has evolved, at least in part, to increase the reproductive success of the actor's social partners. [1]
Evolutionary theory predicted that since amphibians evolved from fish, an intermediate form should be found in rock dated between 365 and 385 million years ago. Such an intermediate form should have many fish-like characteristics, conserved from 385 million years ago or more, but also have many amphibian characteristics as well.