* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> General news -> Ancient life
Post Info TOPIC: Ancient life
Blobrana


L

Posts: 131433
Date:
RE: Ancient life
Permalink  
 

Two researchers have solved a 150-year-old mystery from the dawn of Canadian science, rediscovering a long-lost set of fossilised footprints that -- unbeknownst to William Logan, the pioneering geologist who found them in 1851 -- represent the emergence of animal life on land.
Logan, the iconic 19th-century scientist for whom Canada's highest mountain is named, was the head of the fledgling Geological Survey of Canada in the late 1840s when he was informed by the editor of the Montreal Gazette, Robert Abraham, of unusual markings seen on rocks in a sandstone quarry near the St. Lawrence River.

Read more 


__________________
Blobrana


L

Posts: 131433
Date:
Nitrogen cycle
Permalink  
 

A team of geologists has found evidence that single-celled microscopic organisms completed their evolution by 2.5 billion years ago, more than a billion years after life appeared on Earth. Their geochemical evidence, discovered in ancient rocks, suggests the sudden appearance a modern style nitrogen cycle.

"Nitrogen, which is needed for the production of amino acids and proteins, is essential for life as we now know it, but was not so available early in Earth's history. Only single-celled organisms, and of only a few types, are able to use nitrogen gas from the atmosphere and, in so doing, convert it to ammonia" - Jay Kaufman, a University of Maryland scientist and co-author of a paper published in the February 20 issue of Science. 

According to Kaufman, the new evidence he and fellow geologists from the University of Washington and the University of Arizona uncovered suggests that 2.5 billion years ago bacteria evolved -in response to a rise of oxygen in shallow ocean water -that were able to further convert nitrogen into more biologically useable forms.

"Only a relatively few organisms can assimilate ammonia; others, like plants and animals, need the oxygenated form, nitrate. The rise of microorganisms making nitrogen more available in the form of nitrate, released more energy to biological systems, which likely kick started the evolution of higher life forms" - Jay Kaufman.

The bacteria responsible for the modern nitrogen to nitrate cycle sit on the outermost branches of the microbial tree of life, thus their discovery indicates that microbial evolution and diversification was complete billions of years before animals took the world stage.

Read more

__________________
Blobrana


L

Posts: 131433
Date:
RE: Ancient life
Permalink  
 

A fossil fish from Australia was one of the earliest known vertebrates to reproduce sexually, a study suggests.
Nature journal says the ancient fish was carrying a 5cm-long embryo.
The fertilisation of eggs by sperm outside the mother's body - external fertilisation - is thought to have evolved before sex.
The fossil suggests sexual reproduction - the fertilisation of eggs inside the female's body - evolved sooner than previously thought.

Read more

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

The era when sex became a popular form of reproduction has been fixed by the discovery of a fossilised pregnant fish and her embryo.
Remains of the primitive fish, Incisoscutum ritchiei, have provided the earliest known evidence of copulation and live births in the animal kingdom.
Until the evolution of the armoured fish, sex is thought to have been limited to external fertilisation techniques in which sperm and eggs were squirted into the water to mix.
The species, with the fossil dated at 350-380 million years old, is the same age as another closely related fossilised fish, Materpiscis attenboroughi, which was found last year with a newly born offspring still attached by the umbilical cord.

Read more

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

As the world marks the 200th anniversary of Charles Darwin's birth, there is much focus on evolution in animals and plants. But new research shows that for the countless billions of tiniest creatures -- microbes -- large-scale evolution was completed 2.5 billion years ago.

"For microbes, it appears that almost all of their major evolution took place before we have any record of them, way back in the dark mists of prehistory" - Roger Buick, a University of Washington palaeontologist and astrobiologist.

All living organisms need nitrogen, a basic component of amino acids and proteins. But for atmospheric nitrogen to be usable, it must be "fixed," or converted to a biologically useful form. Some microbes turn atmospheric nitrogen into ammonia, a form in which the nitrogen can be easily absorbed by other organisms.

Read more 

__________________
Blobrana


L

Posts: 131433
Date:
Origins of life
Permalink  
 

The remarkable behaviour of bacteria that have been forced to live without their protective wall has allowed Newcastle University scientists to open a new window on the origins of life on Earth.
All living cells on the planet go through the process of division in order to survive and thrive. Cell division, or binary fission, allows one cell to split down the middle to become two cells.
In the work published in Nature, Newcastle University scientists have found that under some conditions, including treatment with antibiotics, common bacteria switch to a whole new way of increasing in number that may have been used by the first cells to evolve on the planet.

Read more

__________________
Blobrana


L

Posts: 131433
Date:
RE: Ancient life
Permalink  
 

Sponges as earliest animal life
'Chemical fossils' provide evidence for first multicelled creatures

Even Charles Darwin was puzzled by the apparently sudden appearance in the fossil record of a great variety of multicellular creatures -- a rapid blossoming known as the Cambrian explosion. Since then, the origin of animals was found to extend back earlier, through a period known as the Ediacarian. Now, evidence found by researchers at MIT, UC Riverside and other institutions shows that the first complex life forms may in fact have appeared much earlier still.
Our earliest animal ancestors, it appears, were sponges -- multicellular animals that feed by passing seawater though a complex system of internal channels. And these earliest sponges may predate the Ediacarian period by as much as 80 million years, this new evidence shows.

Read more  

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Traces of animal life have been found in rocks dating back 635 million years.
The evidence takes the form of chemical markers (Called 24-IPC) that are highly distinctive of sponges when they die and their bodies break down in rock-forming sediments.
The discovery in Oman pushes back the earliest accepted date for animal life on Earth by tens of millions of years.

Read more 

See also Snowball Earth

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

An international research team of scientists from UC Riverside, the Massachusetts Institute of Technology and other institutions has found the oldest evidence for animals in the fossil record.
The researchers examined sedimentary rocks in south Oman, and found an anomalously high amount of steroids that date back to 635 million years ago, to around the end of the last ice age. The steroids are produced by sponges - one of the simplest forms of multicellular animals.
The researchers argue that the discovery of the sponges is evidence for multicellular animal life beginning 100 million years before the Cambrian explosion, a well-studied and unique episode in Earth history that began about 530 million years ago when, as indicated by the fossil record, animal life diversified rapidly.
The discovery can help scientists reconstruct Earth's early ecosystems and explain how animal life may have first evolved on the planet.

University of California/Riverside 

__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Three billion years ago, a "new" amino acid was added to the alphabet of 20 that commonly make up proteins in organisms today. Now researchers at Yale and the University of Tokyo have demonstrated how this rare amino acid - and, by example, other amino acids - made its way into the menu for protein synthesis. The study appeared in the December 31 advance online publication of the journal Nature.
The rare amino acid the Yale researchers studied, pyrrolysine (Pyl), gave the researchers a molecular handle by being an extreme example of an amino acid that evolved to serve a highly specific need.

Read more 

__________________
«First  <  1 … 7 8 9 10 11 … 21  >  Last»  | Page of 21  sorted by
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> General news -> Ancient life


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard