New findings suggest mammals diversified only after dinosaur extinction left space

Date: July 5, 2016
Source: Queensland University of Technology

QUT evolutionary biologist Dr Matthew Phillips used molecular dating from DNA sequences to challenge the dominant scientific theory that placental mammals diversified 20 million years before dinosaurs became extinct.

In a paper published in the journal Systematic Biology and delivered at the Society for Molecular Biology and Evolution Conference this week, Dr Phillips said biases in models of DNA evolution inflated estimates of when modern mammals, which were once no larger than a guinea pig, diversified and evolved into the animals familiar to us today.


"We can infer that some placental mammals did co-exist with dinosaurs," he said.


"But for 20 years or so the current dominant theory has suggested that their diversification happened more than 80 million years ago, well before dinosaurs became extinct.


"It now appears that the major diversification of placental mammals closely followed the extinction of dinosaurs 66 million years ago, an event that would have opened up ecological space for mammals to evolve into."

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Evolutionary biology: Why cattle, pigs only have two toes

Date:

June 18, 2014

Source:

Universität Basel

Summary:

During evolutionary diversification of vertebrate limbs, the number of toes in even-toed ungulates such as cattle and pigs was reduced and transformed into paired hooves. Scientists have identified a gene regulatory switch that was key to evolutionary adaption of limbs in ungulates. The study provides insights into the molecular history of evolution.

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