Footprints of dinosaurs are considered trace fossils. Dinosaur tracks in Texas are from the Cretaceous age. According to Homer Montgomery, Ph. D., there are three important questions to ask when evaluating whether or not an imprint is a dinosaur track:

(1) How do we know this track was made by a dinosaur? Some are easy to determine. An expert is needed for more difficult calls.

Problems arise when tracks were actually made by birds, mammals, crocodiles, pterosaurs, and turtles.

(2) Where do we find dinosaur tracks? Tracks are found in sedimentary strata. They are usually found in rocks deposited in continental areas, but some can be found shallow coastal waters. According to Dr. Montgomery, differences in the extent and distribution of prints are important for interpretation.

(3) What age are they? Age is determined from the age of the host strata.

The following terminology is needed for the interpretation of tracks:

Trackway Width–the measurement between the outside of the left print to the outside of the right.

Step (also known as pace)–consecutive footprints left to right or right to left.

Stride–consecutive footprints made by the same foot. In order to get an accurate measurement of the stride of a dinosaur that walked with its feet directly in front of each other, you would measure from the heel of one print to the heel of a third print. As an example, a dinosaur might step left-right-left. To measure the stride, you need to measure prints made by the same foot–the left and left.

You can estimate fairly accurately the size of a dinosaur from the size of its footprint.

Small bipeds had a hip height usually 4 to 5 times the footprint length. Large bipeds had a hip height of 4 ½ times the footprint length. An appropriate skeleton length can then be determined from the hip height.

Quadruped measurements are easily determined. In addition to calculating hip height, you can estimate the trunk length by measuring the distance between fore and hind limbs.

How fast was the dinosaur going?

FIRST: measure the stride length. It is best to take three measurements if you can and calculate the average. Also, measure the footprint.

SECOND: determine the hip height. For large bipeds, stride x 4.5. For small bipeds, stride x 5.

THIRD: determine relative stride. Stride length/hip height.

FOURTH: determine Froude number for relative stride.

FIFTH: determine velocity in meters/second. Calculated as square root of (froude # x 9.8 x hip height).

Back to Dinosaurs in Texas
02/11/99