Saturday, June 19, 2010

Drawing and Sketching with Pencils

Visit the pencil display at an art supply store and you'll face an overwhelming selection of drawing pencil options. Selecting a pencil to draw with is a matter of trial and error. Purchase a variety of brands and try them out on different materials. If you need a jumpstart selecting pencils - pick those with softer leads. Even though you may experience some smudging, the tonal quality and deep blacks are worth it. The photograph above shows a number of pencils in my collection, some of which are no longer available (Berol Draughting 314 and the Staedtler Mars Dynagraph). I recommend using the Prismacolor PC935 Black pencil as an all around drawing pencil. Work with a battery powered pencil sharpener which is much easier to use than a tiny hand sharpener.

Friday, June 18, 2010

Ancient Animal Sacrifices

Photograph from Imagechina/AP

Sacrificial remains of humans and animals, believed to be at least 2,700 years old, have been found in central China's Luoyang city (map), Chinese archaeologists say.
The bones are part of a recently discovered burial complex covering nearly a quarter acre (945 square meters) and containing 14 tombs, a water channel, and 59 pits from the Western Zhou dynasty. (Related: "Ancient Mass Sacrifice, Riches Discovered in China Tomb.")
During the Western Zhou period (1100 B.C. to 771 B.C.), the sacrifices of animals—and sometimes humans—to ancestors or deities were a routine part of Chinese culture. The sacrifices were often made to bless houses, said David Sena, a China historian at the University of Texas at Austin.
"In general, there's been a tendency to describe Western Zhou as a more humanistic period, when the practice of human sacrifices"—which were commonplace during the preceding Shang Dynasty—"were waning," Sena said.
"But I think the archaeological evidence shows quite clearly that human sacrifices persisted throughout the Zhou period as well."
—Ker Than

Published June 15, 2010

Friday, June 04, 2010

Flower Hat Jelly

Photograph by e-Photography/Chijimatsu/

might be alluring, but a rare flower hat jelly’s lilac-tipped fringe can deliver a painful sting. Found off Brazil, Argentina, and southern Japan, the jelly’s tentacles can coil and uncoil and are used to capture small fish and other food.

Opalescent Inshore Squid

Photograph by Brian J. Skerry, National Geographic

Opalescent inshore squid, like these off the coast of California, take the mass production approach to species survival. At mating time, a female will litter the seafloor with hundreds of white, fingerlike egg cases containing more than 50,000 eggs.

Thursday, June 03, 2010

New Giant Flying Reptile Found; Hunted on Foot? New pterosaur likely stalked baby dinosaurs in once lush Sahara.

James Owen

for National Geographic News

Published May 28, 2010

A new species of giant flying reptile has been found in the sands of the Sahara, a new study says.

But the 95-million-year-old pterosaur likely preferred life on the ground, spending most of its time stalking prey in what was once a lush wetland.

(See picture: "Giant Flyers Hunted Dinos on Foot?")

The 95-million-year old Alanqa saharicafrom, discovered in 2008 in southeast Morocco, belonged to a pterosaur family that flourished some 70 million years ago.

Jaw and neck bones of the newfound fossil identify it as the oldest known ancestor of the azhdarchids, a type of large pterosaur, said study leader Nizar Ibrahim of Ireland's University College Dublin.

A. saharicafrom had a toothless, beak-like jaw, a long, slender neck, and an estimated wingspan of 19.5 feet (6 meters), the study said.

"That tells us that even these very early azhdarchids were already pretty big and had the same kind of body proportions [as later giant species]," Ibrahim said.

Recent research also suggests that azhdarchids such as A. saharicafrom didn't fly that much. For example A. saharicafrom may have hunted "lizards and little dinosaurs with their long, slender jaws," Ibrahim said—"a bit like a stork or a heron."

"Amazingly Productive" Green Sahara

These winged creatures' light and flimsy bones seldom survive as fossils, and examples from Africa are especially rare.

"All the pterosaur material that has ever been found in Africa could fit on a very small table," he said.

But Ibrahim and colleagues got lucky during their expedition: They found similarly aged fossil fragments that belonged to two other previously unknown and unrelated pterosaurs.

(Related: "Pterosaur 'Runway' Found; Shows Birdlike Landing Style.")

These discoveries suggest that several different pterosaur species lived side by side, eating different prey in the ancient river delta.

For instance, one of the two yet-to-be described species had long, thin teeth that may have been used for grabbing fish while gliding over water. (Read about the Sahara's evolution from delta to desert.)

Surrounded by dry land, this wet ecosystem also supported diverse forms of crocodiles and dinosaurs, Ibrahim noted.

"It was such an amazingly productive environment," he said.

The findings were published on May 26 in the journal PLoS ONE.

Guatemala Sinkhole Seen From Above

Photograph courtesy Paulo Raquec

The 2010 sinkhole in Guatemala (pictured) had likely been forming for several weeks or even years before floodwaters from tropical storm Agatha caused the sinkhole to cave in, the University of Kentcky's Currens said.

"The tropical storm came along and would have dumped even more water in there, and that could have been the final trigger that precipitated the collapse," Currens said.

(Related: "Sinkhole Holds 12,000-Year-Old Clues to Early Americans.")

Published June 1, 2010