Mysterious new seafloor species sheds light on early animal evolution

A new species of the enigmatic marine worm Xenoturbella, dredged from the seafloor of the western Pacific, contributes to understanding of the early evolution of the Bilateria

Date:  December 18, 2017

Source:  University of Tsukuba

Summary:

Researchers have described a new species of the enigmatic marine worm Xenoturbella, named Xenoturbella japonica. Two specimens of this new species were dredged from the seafloor of the western Pacific. These primitive worms, lacking a centralized nervous system, kidneys, and anus, are important for understanding the early evolution of the Bilateria. MicroCT scanning revealed previously unknown structures, and molecular genomic analysis suggested that features of this species may be ancestral to Xenoturbella. This newly identified species is promising for further research on early bilaterian evolution.

Continued  

Role of life's timekeeper -- a novel theory of animal evolution

This novel research disputes modern interpretations of Darwin's theory, though probably remains compatible with Darwin's original hypothesis

Date: April 25, 2016

Source: Bentham Science Publishers

Summary:

This novel research disputes modern interpretations of Darwin's theory, though probably remains compatible with Darwin's original hypothesis.

A new article presents a new theory of animal (metazoan) evolution, suggesting that it was partly mediated through a biochemical oscillator (cycler), named Life's Timekeeper, present in all animal cells. The cycler controls cell maintenance and repair, thereby determining how long cells survive (longevity). It originated in the single-celled ancestor of all animals, which had very short cell longevity.

Animal evolution progressed by extending cell longevity, and this was mediated by extended cycle time of the oscillator. Multi-celled animals and cell-cell communication systems evolved later. The cycler controls the overall rate of development and aging, these time periods being proportionate to maximum cell longevity. Simple animals have cell rejuvenating abilities hence are potentially long lived, whereas complex animals lost such ability and have limited lifespan determined by the maximum potential longevity of their cells.

The theory suggests a two-tier model of animal evolution and so disputes modern interpretations of Darwin's theory, though probably remains compatible with Darwin's original hypothesis. The primary tier, mediated through extended cycle time, prolongs development, aging and hence lifespan of more advanced animals. Longer development enables more cell divisions during embryo formation, increasing the size of the body and the brain and enhancing behavioural and cognitive abilities. 

Continued ...

Was early animal evolution co-operative?

Date:December 6, 2015

Source:Uppsala Universitet

The fossil group called the Ediacaran biota have been troubling researchers for a long time. How do these peculiar organisms relate to modern organisms? In a new study, published in Biological Reviews, researchers from Sweden and Spain suggest the Ediacarans reveal previously unexplored pathways taken by animal evolution. They also propose a new way of looking at the effect the Ediacarans might have had on the evolution of other animals.

The fossil record of animals starts for sure by about 540 million years ago, but their origins before this point have remained obscure. Darwin himself worried about this problem at length in the "Origin of species." But after Darwin was writing, a famous group of fossils were discovered called the Ediacaran biota, named after a remote mine in South Australia where many were found. They are now known to be widespread around the globe from the interval of time just before the animal fossil record starts.

Continued ...