Dinosaur Physiology
Although we cannot examine the internal organs of dinosaurs directly, there
are ways in which we can estimate or predict the properties of these organs.
For example, by looking at the size of the gap within some of the sones in
the skull - the brain case - we can estimate the size of dinosaurian brains.
Looking at the bones also tells us that dinosaurs had a lot in common with
modern animals. The similar structure of their bones (see bone
histology) tells us that they had blood vessels and so we can assume
they must have had a heart to pump this blood round the body.
For more information on how we know what dinosaurs look like click here
The following estimations od dinosaur physiology have been made:
- Blood pressure/heart design-Because some dinosaurs
e.g.Diplodocus had very long necks that were probably held up in the
air (to feed from tall trees) they would have needed a high blood pressure
to pump their blood up to the brain. But, if blood at the same pressure was
pumped into the lungs, for oxygenation, the lungs would probably explode!
This means dinosaurs must have had hearts that were divided and capable
of keeping blood at two, very different, pressures.
- Having a heart divided in this way is an essential property for
warm-blooded creatures. However, this does not mean that it cannot be
possesed by a cold-blooded creature. So all this shows is that dinosaurs
had the potential to become warm-blooded.
- Brain size-The majority of dinosaurs have very
small brains, relative to their body size. However, a few of the smaller
theropod (gl) dinosaurs had brain sizes equivalent to
those of mammals of a similar size.
- Large brains are indicative of warm-bloodedness as, in order
to keep working, the brain needs constant supplies of oxygen and food
and a regular temperature. This evidence supports the idea of a higher
metabolic rate for the theropods with larger brains.
- Dinosaur posture-All dinosaurs had a
more upright, less efficient, posture than the 'sprawling gait' common
amongst modern reptiles. Furthermore, a lot of dinosaurs were
bipedal (gl).
- However, bipedalism does not mean warm-bloodedness - the
chamaeleon (cold-blooded) walks with an upright posture and crocodiles
can walk semi-erect.
- Dinosaur Speed-Studies of dinosaur limb bones and trackways have shown that
they were probably capable of running at high speeds - particularly
the ostrich like theropod dinosaurs.