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Why Birds have Beaks? Researchers discover a Dinosaur Species that shed its “Milk teeth” but did not Replace them

Limusaurus inextricabilis is part of the theropod group of dinosaurs, the evolutionary ancestors of birds

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New York, Dec 23, 2016: Researchers have discovered a dinosaur species that shed its “milk teeth” but did not replace them, a finding that not only changes its anatomy but also explains why birds have beaks and not teeth.

Limusaurus inextricabilis is part of the theropod group of dinosaurs, the evolutionary ancestors of birds.

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The study is based on an analysis of 19 Jurassic ceratosaurian theropod Limusaurus inextricabilis skeletons, discovered in “death traps” where they became mired in mud, got stuck and died.

Their fossils were recovered from Xinjiang in China.

The skeletons ranged in age from baby to adult, showing the pattern of tooth loss over time. The baby skeleton had small, sharp teeth, and the adult skeletons were consistently toothless.

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“This discovery is important for two reasons,” said James Clark, Professor at the George Washington University, US.

“First, it’s very rare to find a growth series from baby to adult dinosaurs. Second, this unusually dramatic change in anatomy suggests there was a big shift in Limusaurus’ diet from adolescence to adulthood.”

In addition, these fossils indicate that baby Limusaurus could have been carnivores or omnivores while the adults were herbivores, as they would have needed teeth to chew meat but not plants.

Chemical makeup in the fossils’ bones supports the theory of a change in diet between babies and adults.

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The fossils also could help to show how theropods such as birds lost their teeth, initially through changes during their development from babies to adults, the researchers noted.

The study was published in the journal Current Biology. (IANS)

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USA: Everything you want to know about Security Clearance; Find out here!

A security clearance allows a person access to classified national security information or restricted areas.

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Former CIA Director John O. Brennan speaks at the Council on Foreign Relations in Washington, March 11, 2014. President Donald Trump revoked Brennan's security clearance Wednesday. VOA
Former CIA Director John O. Brennan speaks at the Council on Foreign Relations in Washington, March 11, 2014. President Donald Trump revoked Brennan's security clearance Wednesday. VOA

U.S. President Donald Trump on Wednesday revoked the security clearance of former CIA Director John Brennan. We take a look at what that means.

What is a security clearance?

A security clearance allows a person access to classified national security information or restricted areas after completion of a background check. The clearance by itself does not guarantee unlimited access. The agency seeking the clearance must determine what specific area of information the person needs to access.

What are the different levels of security clearance?

There are three levels: Confidential, secret and top secret. Security clearances don’t expire. But, top secret clearances are reinvestigated every five years, secret clearances every 10 years and confidential clearances every 15 years.

All federal agencies follow a list of 13 potential justifications for revoking or denying a clearance. VOA
All federal agencies follow a list of 13 potential justifications for revoking or denying a clearance. VOA

Who has security clearances?

According to a Government Accountability Office report released last year, about 4.2 million people had a security clearance as of 2015, they included military personnel, civil servants, and government contractors.

Why does one need a security clearance in retirement?

Retired senior intelligence officials and military officers need their security clearances in case they are called to consult on sensitive issues.

Also Read: Governments Across The World Request Apple for 30,000 Device Information

Can the president revoke a security clearance?

Apparently. But there is no precedent for a president revoking someone’s security clearance. A security clearance is usually revoked by the agency that sought it for an employee or contractor. All federal agencies follow a list of 13 potential justifications for revoking or denying a clearance, which can include criminal acts, lack of allegiance to the United States, behavior or situation that could compromise an individual and security violations. (VOA)