When did the first adaptive radiation of animals occur?

A striking example is the radiation, beginning in the Paleogene Period (beginning 66 million years ago), of basal mammalian stock into forms adapted to running, leaping, climbing, swimming, and flying.

Here we show that in arguably the most evolutionarily successful clade of Mesozoic mammals, the Multituberculata, an adaptive radiation began At least 20 million years before the extinction of non-avian dinosaurs And continued across the Cretaceous-Paleogene boundary.

Perhaps the most familiar example of an evolutionary radiation is that of Placental mammals Immediately after the extinction of the non-avian dinosaurs at the end of the Cretaceous, about 66 million years ago.

An adaptive radiation occurs When a single or small group of ancestral species rapidly diversifies into a large number of descendant species.

Adaptive radiation is the evolutionary process by which many species originate from one species in an area and radiate to different species. The phenomenon of adaptive radiation was first observed by Darwin When he travelled to a place called Galapagos Island.

During the Miocene Epoch (~23–5.3 mya), the adaptive radiation of the apes or hominoids can be observed in the fossil record. The earliest fossils are from Kenya and Uganda. There were 20 or more genera of apes during the Miocene and they exhibited a wide range of body sizes and adaptive strategies.

Mammals were derived in the Triassic Period (about 252 million to 201 million years ago) from members of the reptilian order Therapsida.

Adaptive radiation generally Occurs when an organism enters a new area and different traits affect its survival. this divergence happens in a relatively short interval of geological time. An example of adaptive radiation is the development of mammals after the extinction of dinosaurs.

The major adaptive radiation of mammals occurred following the Extinction of dinosaurs, leaving all that empty niche-space ripe for the taking. Another cause of new ecological opportunity is when the organism changes, not the environment.

Adaptive radiation occurs When members of a population of organisms (same species) isolates itself by forming different diets or living in different locations than other members. Darwin’s finches were once the same species; they came to the Galápagos Islands as one species.

In evolutionary biology, adaptive radiation is A process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches.

How is the spread of mammals an example of adaptive radiation? After the mass extinction 65 million years ago, dinosaurs went extinct and left many habitats open. Mammals evolved rapidly, in geologic time, into many different species.

Adaptive radiation is the Evolutionary divergence of members of a single ancestral line into a series of different niches or adaptive zones.

In adaptive radiation, many different species evolve from a single ancestor species. Each new species evolves To exploit a different niche, such as food source. In the example above, Hawaiian honeycreepers evolved a range of bill forms in response to available food sources on the Hawaiian archipelago.

The first true primates evolved by 55 million years ago or a bit earlier, near the beginning of the Eocene Epoch. Their fossils have been found in North America, Europe, and Asia.

Primates first appeared in the fossil record Nearly 55 million years ago, and may have originated as far back as the Cretaceous Period.

New World monkeys or platyrrhines, one of the three major primate clades, constitute an example of a major mammalian adaptive radiation that Unfolded in isolation in Central and South America during the last 25–35 Ma, resulting in broad ecological and morphological diversity (17, 18).

‘The radiation of mammals’ Outlines the end-Cretaceous mass extinction period 65 mya when over 60 per cent of all living species disappeared. It also describes the Tertiary radiation of mammals through changing climates, and the mammalian evolution on the island continents of Australia and South America.

The origin of the reptiles lies about 320–310 million years ago, in the swamps of the Late Carboniferous period, when the first reptiles evolved from advanced reptiliomorph labyrinthodonts.

The first mammals appear Around 200 million years ago, and the first birds take to the sky. Flowering plants appear. Mass dinosaur extinctions begin. The earliest known placental mammal, the mouse-sized Eomaia, appears around 125 million years ago.

Adaptive radiation occurs When there are different niches in an environment that create multiple selective pressures for evolution. This allows different traits to be selected for and, over time, creates new species.

Adaptive Radiation Examples

• Bush hyrax – the elephant’s closest relative.
• Marsupial radiation.
• Early supercontinents – Gondwana and Laurasia.
• Adaptive radiation in Galápagos finches.
• Phylogenetic tree of life.

Adaptive radiation is a concept in evolutionary biology where the number of species with a common ancestor increase rapidly however they are characterised by great morphological and ecological variations. So, the correct answer is ‘Divergent evolution‘.

The oldest mammaliaform ecological radiation ran from 190 to 163 million years ago In the early-to-mid Jurassic Period — amid the breakup of the supercontinent Pangaea — and involved the first true mammals and their closest relatives.