mammals gave up night life only
Last Updated : GMT 05:21:58
Arab Today, arab today
Arab Today, arab today
Last Updated : GMT 05:21:58
Arab Today, arab today

after dino doom

Mammals gave up night life only

Arab Today, arab today

Arab Today, arab today Mammals gave up night life only

Squirrels, like many carnivores, have a keen sense of smell and acute hearing.
Paris - Arab Today

The earliest mammals were night creatures which only emerged from the cover of darkness after the demise of the daytime-dominating dinosaurs, researchers said Monday.

This would explain why relatively few mammals follow a daytime-active or "diurnal" lifestyle today, and why most that do still have eyes and ears more suitable for living by night.

"Most mammals today are nocturnal and possess adaptations to survive in dark environments," study co-author Roi Maor of the Tel Aviv University told AFP.

"Monkeys and apes (including humans) are the only diurnal mammals that have evolved eyes that are similar to the other diurnal animals like birds or reptiles. Other diurnal mammals have not developed such profound adaptations."

Maor and a team provide evidence for a long-standing theory that tens of millions of years of evading dinosaurs caused a nocturnal "bottleneck" in the evolution of mammals -- the group of warm-blooded, milk-producing creatures that includes our own species.

Because they hid out in darkness for so long, possibly to avoid competition with dinos for food or territory, or being eaten by them, mammals today are not quite on par with fish, reptiles and birds when it comes to daytime vision.

Mammals, apart from primates, lack a part of the eye known as the fovea, which many fish, reptiles and birds have and is replete with photoreceptor "cone" cells for seeing colour in high light.

Instead, they tend to have more "rod" cells, which can pick up scant light in dim conditions, but provide relatively low resolution.

Modern-day mammals which are active mostly by day -- including types of squirrel, tree-shrews, some antelope and many carnivores -- also still tend to have a keen sense of smell and acute hearing, attributes required for living in the dark.

- Primates first -

Maor and a team analysed the lifestyles of 2,415 living mammal species, and used computer algorithms to reconstruct the likely behaviour of their ancestors, and their ancestors before them -- going back to the very beginning of mammals.

The earliest mammal ancestor emerged between 220 million and 160 million years ago, evolving from a reptilian forebear. And it was probably nocturnal, according to the study published in the journal Nature Ecology & Evolution.

Dinosaurs, on the other hand, were likely day-dwellers seeking out sunlight to warm their bodies like reptiles today.

The data revealed that mammals remained nocturnal throughout the Mesozoic period, which ended about 66 million years ago when a massive calamity, possibly an asteroid strike, wiped out the dinos and about three-quarters of life on Earth.

Mammals, then mainly small, scurrying animals, survived, and flourished.

Most stayed nocturnal, some embraced the daytime, and others -- including cats, elephants and cows -- are today a bit of both.

Primate ancestors were among the first mammals to become strictly diurnal -- possibly as long as 52 million years ago -- the researchers found.

This explains why our primate family is better adapted to the sunlit way of life -- we've had more time to evolve and adapt.

The reason for the shift from night to day is not clear, said Maor, but may have included a "reduced risk of predation" to early mammals.

The study, while showing a strong correlation between the death of dinos and the daytime emergence of mammals, cannot conclude that one led to the other.

Source: AFP

arabstoday
arabstoday

Name *

E-mail *

Comment Title*

Comment *

: Characters Left

Mandatory *

Terms of use

Publishing Terms: Not to offend the author, or to persons or sanctities or attacking religions or divine self. And stay away from sectarian and racial incitement and insults.

I agree with the Terms of Use

Security Code*

mammals gave up night life only mammals gave up night life only

 



Name *

E-mail *

Comment Title*

Comment *

: Characters Left

Mandatory *

Terms of use

Publishing Terms: Not to offend the author, or to persons or sanctities or attacking religions or divine self. And stay away from sectarian and racial incitement and insults.

I agree with the Terms of Use

Security Code*

mammals gave up night life only mammals gave up night life only

 



Arab Today, arab today Modern colorful bedroom renovation

GMT 11:23 2017 Thursday ,21 December

Modern colorful bedroom renovation
Arab Today, arab today For the Variety of Interior Design Styles

GMT 11:14 2017 Tuesday ,19 December

For the Variety of Interior Design Styles

GMT 15:06 2016 Monday ,12 December

Serbian FM to visit China

GMT 23:29 2017 Thursday ,16 February

Home built on sand castles-style costs $8m

GMT 23:01 2018 Monday ,15 January

BAS launches new website

GMT 23:09 2016 Monday ,19 September

US Police Detonate Possible Bomb in New Jersey

GMT 08:26 2016 Wednesday ,19 October

Spending cuts a must in Gulf

GMT 08:23 2017 Wednesday ,06 September

PyeongChang headed towards right direction: Olympic expert

GMT 12:14 2016 Friday ,16 December

'Birdman' director to put migrant boat 'tomb' on show

GMT 23:33 2014 Monday ,06 October

Decorating your outdoor, living rooms

GMT 15:00 2014 Thursday ,01 May

December 21 - January 18

GMT 15:57 2017 Sunday ,26 February

Ooredoo Posts 4 Pct Increase in Net Profit in 2016

GMT 01:53 2017 Saturday ,21 October

November23rd-December21st

GMT 09:26 2017 Saturday ,01 July

Ebola virus death toll in West Africa rises to 887

GMT 19:37 2018 Friday ,26 October

Saudi Arabia set for series of privatizations

GMT 14:56 2017 Thursday ,21 December

Ryanair says formally recognises pilots' union

GMT 10:09 2017 Tuesday ,19 December

Lebanon remains occupied

GMT 01:09 2017 Sunday ,17 December

Taiwan elects its first female president
Arab Today, arab today
 
 Arab Today Facebook,arab today facebook  Arab Today Twitter,arab today twitter Arab Today Rss,arab today rss  Arab Today Youtube,arab today youtube  Arab Today Youtube,arab today youtube

Maintained and developed by Arabs Today Group SAL.
All rights reserved to Arab Today Media Group 2021 ©

Maintained and developed by Arabs Today Group SAL.
All rights reserved to Arab Today Media Group 2021 ©

arabstoday arabstoday arabstoday arabstoday
arabstoday arabstoday arabstoday
arabstoday
بناية النخيل - رأس النبع _ خلف السفارة الفرنسية _بيروت - لبنان
arabstoday, Arabstoday, Arabstoday