"The need now is to figure out, could animals have evolved twice?" Dr. Maloof said.
Because many researchers believe the creature could fly, placing it on the dinosaur lineage suggested that the ability evolved twice, or was subsequently lost and then recovered.
The Durham University academic traced the roots of Little Red Riding Hood to a folk tale called The Wolf and the Kids, which subsequently "evolved twice", he claims in his paper, published this week in scientific journal Plos One.
Given this, homeothermy must have evolved twice.
Alternatively, feathers could have evolved twice during the course of evolution.
But Holland thinks this body plan evolved twice: once in the ancestor of higher animals and again independently in Buddenbrockia.
If they evolved twice or more, that could help shake up a significant portion of the vertebrate family tree.
Now three paleontologists propose that this type of molar was not a singular key innovation, but evolved twice.
With the evidence we have, either story is possible: maybe the nervous system has evolved twice, or maybe it was reduced in sponges.
Fig. 2 Foregut fermentation has independently evolved twice in mammals, first in Rumantia, a lineage of cetartiodactlys that includes cow, sheep, moose, and giraffe and then again in colobus, langur, and proboscis monkeys.
Microbats, the group of bats that emit echolocation signals from the larynx, came under close scrutiny because, surprisingly, some molecular studies divided them into two groups that diverged long ago, suggesting that echolocation evolved twice.
