As long as dinosaurs have been known, there has been speculation about their appearance. Fossil feathers can preserve the morphology of color-imparting melanosomes, which allows color patterns in feathered dinosaurs to be reconstructed. Here, we map feather color patterns in a Late Jurassic basal paravian theropod dinosaur. Quantitative comparisons with melanosome shape and density in extant feathers indicate that the body was gray and dark and the face had rufous speckles. The crown was rufous, and the long limb feathers were white with distal black spangles. The evolution of melanin-based within-feather pigmentation patterns may coincide with that of elongate pennaceous feathers in the common ancestor of Maniraptora, before active powered flight. Feathers may thus have played a role in sexual selection or other communication.

image source 1
sciencemag.org

Thanks to News.BBC.co.uk.


Staying cool, or keeping warm?
It is one of the simplest, but most enigmatic mysteries of nature: just why do flamingoes like to stand on one leg?

The question is asked by zoo visitors and biologists alike, but while numerous theories abound, no-one has yet provided a definitive explanation.

Now after conducting an exhaustive study of captive Caribbean flamingoes, two scientists believe they finally have the answer.

Flamingoes stand on one leg to regulate their body temperature, they say.

Matthew Anderson and Sarah Williams are comparative psychologists based at Saint Joseph’s University in Philadelphia, US who are interested in the studying the evolution of behaviour.

“Flamingoes captured my attention for a variety of reasons,” says Anderson.

“Scientifically speaking, their highly gregarious nature makes them an ideal species for investigating social influences on behaviour.

“Aesthetically speaking, they are large, beautiful, and iconic.

“Perhaps most importantly, I was very surprised to discover how little systematic, hypothesis-driven empirical research had been conducted on flamingoes.”

Lateral thinking

Anderson and Williams’s research began by studying laterality in flamingoes: whether they show any preference over which side of their bodies they use for various tasks, just as a human may be right or left-handed.

They found that flamingoes prefer to rest with their heads on one side more than the other, and that which side a flamingo rests its head determines how aggressive it is toward others in the flock.

That led the researchers to investigate whether flamingoes also prefer to stand on one leg more than the other, and from there, why they stand on one leg at all, empirically testing the question for the first time.

To investigate, Anderson and Williams spent several months observing the habits of captive Caribbean flamingoes (Phoenicopterus ruber) at Philadelphia Zoo, Pennsylvania, each of which carries a leg band that allows individuals to be identified.

At first, they examined whether standing on one leg helps reduce fatigue in the birds’ legs, or helps flamingos escape from predators more quickly, by shortening the time to take flight.

Both are commonly proposed as reasons for unipedal resting in flamingoes.

The scientists ruled out each as a benefit of standing on one leg, as their research showed it took flamingoes longer, and therefore more energy, to move forward after resting on one leg than after resting on two.

The birds also showed no preference for which leg they stood on.

Nor did standing on one leg help the birds balance when conditions were windy, another proposed idea.

Cool wading

However, the researchers did find that flamingoes prefer to stand on one leg far more often when they are standing in water than when standing on land, they report in the journal Zoo Biology.

“As water invariably draws away more body heat, this result supports the thermoregulation hypothesis,” says Anderson.

In short, the birds stand on one leg to conserve body heat. If they put two legs in the water, rather than one, they would lose more heat than is healthy, particularly as they spend so much time wading.

“The results provide definitive evidence that thermoregulation is a principal function of unipedal resting in flamingoes,” Anderson confirms.

The birds also likely alternate which leg they stand on to avoid one leg becoming too cold.

“If they stood on one leg consistently, they would risk greater loss of body heat and potential tissue damage in the cold,” says Anderson.

The researchers also discounted some other more outlandish theories, such as one that suggests standing on one leg helps flamingoes circulate blood better by limiting the Effects of gravity on their circulatory systems.

But they don’t eliminate the idea that there may be added benefits as well as conserving body heat.

“Given the wading lifestyle of flamingoes, perhaps unipedal resting helps reduce fungal or parasite load as well,” says Anderson.

Others birds, such as herons, storks, ducks and many others also often stand on a single leg in water, perhaps for the same reasons as flamingoes.

But as flamingoes tend to spend much longer filter feeding in water than these other birds, this remains speculation, Anderson says.

Just like in Aesop’s fable, scientists now find that crows might indeed learn to drop stones in pitchers to raise the height of water inside, in this case to bring a tasty, floating worm within reach.

This suggests the fanciful millennia-old tale might actually have been based on fact.

In Aesop’s fable, “the crow and the pitcher,” a thirsty crow dropped stones in a pitcher to raise the water level and quench its thirst. Past experiments have shown that crows and their relatives — altogether known as corvids — are indeed “remarkably intelligent, and in many ways rival the great apes in their physical intelligence and ability to solve problems,” said researcher Christopher Bird at the University of Cambridge in England.

Smart as primates?

In recent years, scientists revealed that orangutans were able to use water as a tool, much as in the crow and pitcher fable, spitting water into a tube to bring a peanut within their grasp. Researcher Nathan Emery, a comparative psychologist at Queen Mary University of London, noted those experiments were a challenge to see if crows were capable of the same feat.

Bird and Emery tested four adult rooks — intelligent birds belonging to the corvid family — with a clear plastic tube 6 inches high (15 cm) filled partly with water and large and small stones. These rooks had previously shown experience using and manufacturing tools, such as making hooks out of wire to pull in a bucket containing food, or employing sticks and stones to release a trap door to deposit a meal.

All four rooks lived up to the fable. Rooks named “Cook” and “Fry” were successful on their first attempt, and “Connelly” and “Monroe” took two tries.

“The behavior of the rooks reported in the paper is amazing,” said biologist Natacha Mendes at Institute of Cognitive Neurology and Dementia Research in Magdeburg, Germany, who did not participate in this study. (Mendes and her colleagues performed the experiments where orangutans mimicked the crow and pitcher fable.)

The birds proved highly accurate, placing in only the precise number of stones needed to raise the water level to a reachable height. Instead of trying to get the worm after each stone was dropped, they apparently estimated the number required from the outset and waited until the time was right. The rooks selected larger stones over smaller ones for maximum effect.

“We’ve now found in many cases that the crows perform as well or even outperform the apes in these sort of tasks,” Emery told LiveScience.

In the future, the researchers would like to vary aspects of the experiments — for instance, using birds that have no prior tool-use or tool-making experience, or using liquids that don’t act like water, or using materials that do or don’t float.

Read more at livescience.com.