Evolution

The evolutionary history of parrots shows evidence that within the neotropocal parrots, morphotypes such as body shape within parrot clads are homologous structures and traits passed down from ancestors with similar body shapes. Recent studies suggest that diversification into these different ancestral morphotypes took place between 30-35 million years ago, around which time the common ancestor of these birds colonized North, central, and South America. Following the colonization occurred a rapid diversification period where ancestral parrots use adaptation to aid in its survival within their new local living conditions. Speciation of only a few morphotypes over time had diversified into over 150 species that live today throughout the Americas and the islands of Antilles.

“The clear picture that has emerged in the last decade from phylogenetic analyses of parrots is that these species are all in different evolutionary lineages. Evolutionary patterns tell us that on a broader scale, similar morphotypes have evolved convergently in different lineages of parrots. Whether similar mutations in the same or different genes that produce these body plans have been promoted by natural selection in different lineages remains an exciting question for future investigation. (TOFT, 2015)”

Through the study of fossil calibrations and various molecular datasets, many researchers have given a rough time stamp on the biggest diversification shift from ancient parrots to the more modern ones we’re familiar with today, placed before the end of the Cretaceous period. In 2001, Joel Cracraft of the American Museum of Natural History examined the geographic distribution of different groupings of birds across various regions. To understand this species macroevolution, he aligned the branching patterns in their phylogeny along with the geological history data of each region. His research concluded that many of the major bird groups showed patterns of continental distribution to align consistently with the evolution of the ancient supercontinent Gondwana. Gondwana was a large land mass that broke up gradually, making up most of the modern continents we know today, such as Africa, south America, Australia, Madagascar, Antarctica, the Indian subcontinent, and the Arabian Peninsula.

“Since many of these bird groups were found on several parts of what was once a cohesive supercontinent, Cracraft concluded that they had originated in Gondwana in the Cretaceous and diversified as different populations became isolated from each other by the separation of the continents, a process known as vicariance. While this seemed like convincing evidence to many, others were quick to point out that it assumed that these ancestral birds would be unable to disperse from one continent to another, an assumption that seems shaky given the evident ability of many (but not all) modern birds to fly long distances. And so, the debate as to when and where the birds diversified continued. (TOFT, 2015)”

References:

Evolution of birds - Wikipedia

Parrot - Wikipedia

What Parrots Tell us About the Origin and Evolution of Birds | ScienceBlogs

The Parrot's Surprising Evolutionary Past | amomentofscience - Indiana Public Media