The suricate, an insect-eating mongoose from southern Africa. Research
shows mongooses’ teeth wear according to diet. (Dr. M.E. Taylor, ROM)




How animals’ teeth wear down

depends on diet, researcher finds

By Lorraine Brown
A mammologist at the Royal On-
tario Musuem in Toronto has
discovered that the teeth of
mongooses show patterns of wear
that can be related to the animal’s
diet, and how it eats.

Dr. Mark Taylor, associate
curator of mammalogy at the ROM,
found the wear patterns on the teeth
of African mongooses and closely-
related animals. His discovery
means that scientists will be able to
find out what foods different
animals eat, without having to kill
them and examine their stomach
contents. The analysis can be done
on casts taken from the teeth of
anaesthetized animals, specimen
skulls, or even fossils.

Dr. Taylor said that research into
patterns of wear on teeth was



















By Pippa B. Wysong

A Montreal research team has
|} developed robot fingertips that
allow heavy robot hands to pick up
delicate objects and an inflatable
robot arm that can bend around
corners. :

Roboticists Drs. Roman Baldur
and Andre Bazergui of the Ecole
Polytechnique de Montreal have
made prototype Force Sensing
Grippers (bubble fingertips for
| robot hands) and an_ Inflatable
Manipulator (a bendable, elephant-
truck-like arm).
_ One of the problems with robot
fingers is that they are not suitable
| for picking up delicate objects. Of-
ten, items such as mushrooms, eggs
| or fruit that are picked up by
robotic hands get punctured, or
else squashed. Needed were
fingers that were softer and that

could be adjusted to the delicacy of
the operation.

The Force Sensing Grippers help
solve these problems by covering
robot fingers with inflatable bub-
bles. Depending on the type of ob-
ject being handled, the bubbles can
be made of material as soft as
surgeons’ gloves or as hefty as
bicycle inner tube rubber, says Dr.
Bazergui.

When picking an object up, the
bubbles become slightly squished,
representing, a- change in pressure.
The pressure it takes to pick an ob-
ject up can be determined by a
gauge located underneath the bub-
bles and the information fed into a
computer. Operators then have a
record of how much pressure or
force is needed for handling certain
types of objects.

The bubbles will also make it

Robots to get air-powered limbs

easier for robot hands to pick up
spherical objects because they
won’t slide.

Dr. Roman is also adapting the
bubble fingers to pick mushrooms.

The Inflatable Manipulator can
reach awkward places because it
can bend around corners. Dr.
Bazergui likens it to an ‘‘elephant
trunk’’.

The manipulator is like cylin-
drical balloon. It can be inflated to
the desired length and then be
‘pinched’ in places to make it bend.

In order to pinch the cylinder,
the researchers have designed little
inflatable ‘‘muscles’’ that are con-
trolled by compressed air.

The research has been supported
by a Strategic Grant from the
Natural Sciences and Engineering
Research Council.

(Canadian Science News)

originally done on fossil teeth from
primates, as part of some studies on
early man, by British scientist Dr.
Alan Walker in 1978.

Dr. Taylor wanted to apply the
same type of analysis to animals. So
he examined casts of teeth from one
family of mammals, the Viverridae,
which ranges from the dwarf
mongoose (weight 150 to 240 grams)
to the 10-kilogram African civet (a
cat-like animal).

Dr. Taylor used skulls from
collections at the ROM, the British
Museum (National History) and the
Museum of Comparative Zoology at
Berkley, California. He made molds
of the teeth with dental impression
material, then made epoxy resin
casts from the molds.

Both the molding and casting
material were extremely fine-
grained, so that tiny surface details
would show up on the tooth casts.
Then he examined small sections of
the casts with an_ eiectron
microscope.

By limiting his study to one family
of mammals, Dr. Taylor hoped to
remove factors such as different
arrangements of jaw muscles and
different eating behaviours that
might affect tooth wear patterns.
The Viverridae were ideal; they have
similar teeth and jaws, but different
diets — everything from fruit to in-
sects, molluscs and vertebrates —
and different habitats.

Dr. Taylor wasn’t sure he’d find
anything other than a smooth,
polished surface on the teeth. But
once he’d examined the specimens
under the scanning electron
microscope, he discovered tooth
wear patterns — not visible to the
naked eye — that differed according
to diet.

He examined the cutting surfaces
of the carnassials, pre-molars in the
upper jaw that are adapted to

tearing flesh. These teeth are found
in all members of the Viverridae,
and play the same functional role.
But Dr. Taylor discovered that they
wear differently, depending on the
animal’s diet.

Those Viverridae that eat ver-
tebrates had deep vertical grooves
on the teeth. Those that eat mainly
insects had pitted tooth surfaces.
Some had both pits and grooves, in-
dicating a diet of insects as well as
small rodents and reptiles.

A fourth group had teeth with
smooth surfaces and shallow
grooves at right angles to each
other. Horizontal grooves indicate
that the animal holds its prey with
its paws and tears food off using the
teeth like a sharp rake, while vertical
grooves are formed from chewing,
Dr. Taylor says.

The relative smoothness of the
tooth surfaces may be due to a
polishing effect of fruit, which
represents a major component of
the diet of animals in this fourth
group, he adds.

“Many of these animals are dif-
ficult to get hold of, and some are
quite rare,’’ says Dr. Taylor. ‘‘An
advantage of this technique is that
we can work with museum
specimens.”’ '

In the future, Dr. Taylor hopes to
continue his research on live
animals, anaesthetizing them to get
tooth impressions in the field.

The technique could also be used
on fossil teeth from extinct species.

Dr. Alan Hannam, of the Faculty
of Dentistry at the University of
British Columbia, provided
assistance with the microscope
work. =~

The research on the mongoose
teeth was funded by Agriculture
Canada and the Medical Research
Council of Canada.

(Canadian Science News)













By Carolyn Hoskins

A road-worthy commuter car that
f gets more than triple the mileage
| per litre of typical North American
cars has been designed and built by
the University of Saskatchewan’s
| Department of Mechanical
| Engineering.

Designed to take a single driver
to and from work, the ‘Nexus’ car
conforms to Canada’s standards
for crash-worthiness and is licensed
to run on public roads.

Here



itcomes.........
AS

The Nexus, a lightweight, fuel-efficient co
of students at the University of Saskatchewan. (Photo: Barry Hertz)

Researchers build a

The lightweight (340 kilograms)
vehicle has been developed by a
team of graduate students, directed
by Professor Barry Hertz.

The unconventional-looking
tricyle car has two outrigger-type,
covered front wheels and one
power-driven rear wheel. The
nosecone-style front has a surface
area of only 1 square metre to
minimize wind resistance.

The nose is filled with plastic
foam, which in crash simulations
compresses to absorb the impact



Sei

mmuter car designed by a team

lightweight, efficient automobile

and protects the driver. Canadian
standards require that drivers must
be able to survive a head-on impact
with a wall at 48 kilmetres an hour.

The Nexus (‘connecting link’) is
powered by a Suzuki Quad Runner
250cc, air-cooled engine and has a
top speed of 145 kilmetres an hour.
At 100 kilometres an hour, the
car’s fuel consumption is only 2.08

- litres per 100 kilometres.

Dr. Hertz says Nexus can be seen
as a link between the motorcycle
and the passenger car or between
aircraft and a motor vehicle. Em-
ploying many aerodynamic prin-
ciples, the design has a drag factor
(a measure of air friction) of only
0.22, while that of a typical com-
mercial car would be about 0.4.

The Nexus body is a composite
of glass fibres, while the chassis,

necessary for -road — safety
requirements, is made out of
aluminum.

Dr. Hertz says that there has

been a ‘‘fantastic’’ response from
all over the world, including
representatives of some major car
manufacturers. Right now, each
Nexus is hand built at a cost of
$100,000 each. Hertz estimates that
$1 billion would be required in
start-up costs to make a production
line version selling for about
$6,000.

The U of S Department of
Mechanical Engineering has a
worldwide reputation in designing

fuel-efficient vehicles. In 1986, the
department broke the record for
World Fuel Economy in the Shell
Fuelathon by designing a 38-
kilogram vehicle that could get
2014 kilometres a litre. That car will
appear in the latest edition of the
Guiness Book of World Records.

However, the world-record
vehicle was never intended for
normal use, Hertz says.

What makes Nexus so exciting is
“that we have demonstrated that
we can get phenomenal mileage



....and there it goes......

with a normal power train by
keeping the air resistance and
weight down,”’ Hertz says.

He sees Nexus as a catalyst to get
people thinking about the concept,
‘If we can convince people that we
can have crash-worthiness in a
light-weight car then we will have
achieved something,’’ he says.

The development of Nexus was
funded by a grant from Transport
Canada.

(Canadian Science News)

Nexus incorporates construction techniques and design features often used
in aircraft to reduce its weight and air resistance. (Photo: Barry Hertz)