- The impression left by a foot in a sediment or other substrate
- Two or more consecutive footprints belonging to a particular animal progressing in a given direction
- Tracks and track ways may provide the following types of information about dinosaurs:
- Individual Dinosaur Behavior
- Idiosyncracies, e.g., resting, trailing, etc.
- Group Behavior
- herding characteristics
- pack hunting
- Interactions between species
- Types of dinosaurs living in an area when no bones are preserved.
- Information about past environments preferred by dinosaurs
Dinosaur Behavior Not Indicated by Tracks
- Habitual tail dragging
- Swimming or constant immersion in water
- Obligate quadrupeds rearing up on their hind legs
- Intraspecific competition
- Interspecific confrontations
Dinosaur Stride Length and Speed
Martin: pages 162-165
- In a trackway, the distance between two successive steps made by the same
- Stride length is related to leg length
- For a given individual, the greater the stride length, the greater the
- A shorter individual has to take more steps to equal the velocity of a
taller individual. [stride rate = steps/unit time]
Relative Stride Length (sr)
Dimensionless Speed (vd)
- sr = sl / ll
- where sl = Stride Length and ll
= Leg Length for each animal.
- Note: (sr) is a dimensionless number
- sr normalizes for differences in leg length.
- A shorter individual will have a shorter stride length than a taller
individual, even if both are moving at the same speed. The shorter
individual will have a greater stride rate.
- sl can be measured directly from the
can be measured from from dinosaur skeletons and equals the distance from
the ground surface to the acetabulum of the pelvis.
- However, in most cases it is not known exactly which dinosaur made the
- Even if the species is known, the size of the individual making the
trackway is likely different from the size of the known skeleton(s).
- Paleontologists have developed a formula for estimating leg length
from footprint length.
* (C), where fl
is the measured footprint length and C is a constant empirically
determined by measuring the ratio of leg length to foot length from known
- The value of C varies depending on the kind of dinosaurs.
Some paleontologists have calculated C = 4.0, others C = 4.5 for
small theropods, others C = 5.5 for large theropods.
- Martin (page 162) suggests using an average value of 5.0
- For example, if a footprint is 45 cm long, the leg length = 45 cm
* 5 = 225 cm
- Using C = 4, ll
= 180 cm. If C = 5.5, ll
= 248 cm.
- sr = sl / ll
- If a dinosaur had a stride length of 307 cm and a leg length of 225 cm
- the relative stride length = 307 cm / 225 cm = 1.4
- the greater the stride length, the greater the speed.
- Dimensionless speed (vd) accounts for variation in
overall body size.
- A smaller dinosaur with the same relative stride length as a larger
dinosaur will have a lower velocity.
- Dimensionless speed can be determined graphically from relative speed
length using the graph on page 164 (Figure 7.7)
- vd is related to the actual speed (v) by
the following formula
- vd = v / (ll *
- where ll = leg length in meters and g =
gravitational acceleration = 9.8 m/sec/sec
- rearranging the equation, solve for v
- v = vd * (ll *
- for our dinosaur with sr = 1.4, figure 7.7 indicates
vd = 0.45
- v = vd * (ll *
- v = 0.45 * (2.25 m * 9.8 m/s2)1/2
= 0.45 * 4.7 m/s =2.1 m/s = 7.6 km/h
- The fastest speeds estimated from trackways are about 40 km/h for small
and medium-sized theropods.
THE GLEN ROSE TRACKWAY