Zoo keeper Karen Vacco walks into the cage that a red-ruffed lemur named Brass shares with his brother, Copper, and his sister, Gold.

"I'm going to be mean," the keeper warns. "I'm so sorry! You're so trusting."

	Pam Panchak, Post-Gazette Top: Anesthesia gas puts Brass to sleep for his physical. Bottom: Once Brass is under, the exam begins. Click photo for larger image.

With a deft flick of the wrist, Vacco catches the lemur in a small net as he scampers by. Murmuring reassurances, she lines up the opening of the net with that of a crate to drop him in, and sets off for the vet's office a short walk away.

Brass clutches the opening of his carrier with slender, black, nail-tipped fingers. His round, unblinking eyes watch the scenery go by as he is taken from his Tropical Forest exhibit home to his annual doctor's appointment in the animal hospital at the Pittsburgh Zoo and PPG Aquarium.

Lemurs may not be the stars of a zoo, but to people who study early primates and to conservationists, they are fascinating creatures.

As the sign on their exhibit space says, lemurs are not apes and not monkeys. Along with tarsiers and lorises they are prosimians, meaning "pre-monkey," and they comprise a subsection of the primate order.

On the family tree of living primates, which includes monkeys, apes and humans, lemurs would be the first branch, explained Chris Beard, head of vertebrate paleontology at the Carnegie Museum of Natural History.

"Probably somewhere around 60 million years ago, . . . we did share a common ancestor with lemurs and monkeys and apes," he said. "In other words, this would have been the ancestor of all living primates."

Chimpanzees and humans are more closely related, probably having a common relative about 7 million years ago, Beard added.

A closer look

	Pam Panchak, Post-Gazette After it's all over, zoo keeper Karen Vacco cradles a groggy Brass. Click photo for larger image.

Some of the similarities and differences between lemurs, apes and monkeys were easy to spot during Brass's annual physical.

The lemur is calm as Vacco wraps him in a blanket and cuddles him. Associate veterinarian Dr. Rae Gandolf injects him with a sedative so that he'll relax and breathe the anesthesia gas that will make him sleep through the 30-minute checkup.

Apes and monkeys sometimes get annoyed with their observers and will make faces or throw things, Beard said. Lemurs are the most primitive of the living primates, and while they are not as smart as their distant cousins, they seem to be more gentle.

"Lemurs, for my money, are probably the most beautiful of all primates," he said.

To Ingrid Porton, coordinator of the lemur species survival program and primate curator at the St. Louis Zoo, "They're darn awful cute."

Brass looks vulnerable and almost childlike as he lies limp on the examination table. The once-over begins with measurements of his temperature and pulse rate. The 16-year-old weighs in at seven pounds.

Veterinary technician Tammy Munch passes a wide wand over Brass's body, looking for and finding the identification transponder implanted under the skin of his back.

Gandolf looks into his eyes with an ophthalmoscope.

"The optic nerve looks normal and the [blood] vessels look normal," she says. "The cornea is nice and clear."

Brass, like zoo workers, other primates and some other suceptible animals, is tested regularly for exposure to tuberculosis. A small amount of fluid containing a TB protein is injected into his eyelid.

Why that wince-worthy location? If he had been exposed to tuberculosis, his eyelid would swell in reaction. But by then, he'd be back to business-as-usual in his cage. A puffy eye is easier to spot from a distance than a bump on a furry arm.

Strong sense of smell

Like other primates, lemur eyes face forward, rather than to the side, giving them good depth perception, Beard said. But unlike their evolutionary cousins, their eye sockets are not solid bone.

"A lemur is kind of halfway in between a dog and a monkey in that respect," he said. Also, they depend more on their sense of smell than do humans, who are highly visual creatures.

Porton said that like dogs and cats, lemurs have rhinariums, a moist nose tip that enhances the ability to smell. Most primates don't have that.

Brass's delicate cat-like whiskers would not be found on monkeys or apes, either, she said.

For the exam, a small clip is placed on Brass's fingertip, allowing vet staff to monitor his blood oxygen levels. His soft, leathery palm is well marked by wrinkles and looks, as Beard put it, like it could belong to a wizened old man.

Lemur hands look more human than monkey hands do, he added.

"Lemurs, like all primates, have nails on their fingers and toes, rather than claws," Beard said. "That's a critical feature."

But prosimians don't use their hands and tools to brush each other's coats. They have special teeth that jut out from the jaw called the dental or grooming comb.

Sometimes Brass and his family try to tidy their long-haired keepers, but won't let the human handlers remove long strands that are caught in their teeth, Vacco says.

"He's got a lot of worn down teeth, which is common for them," Gandolf says as she peers into Brass's mouth.

"It doesn't seem to affect them," Vacco says. "He'll still eat raw carrots and sweet potatoes, no problem."

Gandolf continues Brass's physical examination by feeling his chest, belly and limbs. Lemurs are prone to getting a disease that thickens their bones and joints.

"It's real easy to feel when they have it badly because they're just stiff," she says. "Their tails don't even bend well."

The vet doubles over Brass's fluffy tail, demonstrating that he seems to be in fine, flexible form, but later takes several X-ray images to verify that all is well.

Three vials of blood are drawn for basic tests. A sample will be kept until the freezer is full or a catastrophe occurs, Gandolf notes wryly. If a new disease crops up in the future, or a researcher needs it, the zoo has specimens from a variety of animals in storage that could be useful.

After a dose of rabies vaccine and some final checks, Brass is allowed to come out of the anesthesia, cradled in Vacco's arms. He spends a few more hours at the zoo hospital under the watchful eyes of vet staff before Vacco takes him back to his home.

Hanging on by a thread

In her role as the species survival program coordinator, Porton in St. Louis keeps tabs on all lemurs in captivity in American zoos. She is also involved in efforts to conserve the animals in the wild.

Lemurs call Madagascar home, and prosimians are the only kind of primate, other than humans, found there. The lack of competition likely aided their survival, Porton said.

Genetic studies have shown that there are many kinds of lemurs.

"Right now the count is up to about 70 different types, which is pretty amazing," Porton said.

Scientists don't know how lemurs got to the South African island, or when, Beard said.

"There are a lot of strange animals and plants on Madagascar today that live nowhere else on Earth," he said. "Lemurs are Exhibit A in that whole range of biodiversity."

But deforestation and hunting have endangered many species, including the black-and-white-ruffed and red-ruffed ones like Brass. To Beard, lemurs make a far more poignant case for conservation efforts than some better-known animals.

"Lemurs are actually more compelling because they are much much closer to us in an evolutionary sense than panda bears are," he said. "They're kind of hanging on by a thread today after evolving for 50 million years or so."

Beard said that all over the world, there are early primate fossils that share features with lemurs. In particular, almost complete skeletons of a 55 million-year-old species called Notharctus have been found in Wyoming, and from tip to tail they closely resemble living lemurs.

"Lemurs are the best evidence we have, along with their fossil relatives like Notharctus, of what these earliest human relatives would have looked like," Beard explained. "Lemurs provide the best modern analog we have for these earliest phases of primate evolution."

Back home again

Unaware of all the human interest in him and his kind, Brass is wide awake by the time Vacco takes him back to his cage, away from public eyes, in the afternoon. He immediately runs out of the carrier to sit quietly on a shelf.

It's "almost like he's sulking, like he knows something happened to him," Vacco says. "He's really not quite sure what it was, so he's not happy about it."

His siblings approach him to sniff the strange scents of the animal hospital on his fur. Vacco feeds him some grapes, banana and plenty of water.

The next day, Brass is back to his usual self except that his TB-tested eyelid is a little puffy. It's probably nothing, but just to be sure, soon the lemur will have something else in common with his human cousins:

A follow-up doctor's appointment.