HGMS Dinosaur Tracks Field Trip
August 6, 2005
STOP 1B "R. T. Bird Site and Ozark Trails"
Just south of the "Main Site" is a track site that is usually under water
and seldom visited by tourists, but which contains some of the most
historically important and impressive tracks. These include the
remains of Roland Bird's famous trackways along the west bank, which
features several parallel trails of sauropod tracks and a theropod
trail following the same path. This has often been interpreted as an
ancient chase scene. Others suggest the theropod was merely following
from a distance. Bird and a local crew removed several sections of
these trails in the early 1940's, which are now exhibited at the American
Museum in New York and a number of Texas museums and universities. Unfortunately,
the removal of the tracks contributed to the disintegration of the
track bed here, and the tracks that remain are significantly eroded.
However, on the opposite bank are three distinct sauropod trackays
known as the Ozark trails, which are still in good shape. Mud tends
to accumulate along this bank, helping protect the tracks. All of
the sauropod tracks here are heading south--parallel to the R.T. Bird
trails--and evidently represent a sauropod "herd." The prints vary
somewhat in size; the largest are over a meter long.
They are called the "Ozark" trails because the first fairly
accurate map of these trackways was made by a team from Ozark
Bible College in the late
1970's. I and my colleagues (including Tim Bartholomew and Ron
Hastings) extended and refined the mapping here in the 1980's
and 90's. The prints in the Ozark trail closest to the center
of the riverbed are the largest, show no
front prints, and are unusually triangular in shape. Many
show all five claw impressions, and in some cases, look so
fresh they could have been made yesterday. One shows
a large flap of mud (now limestone) squished up by the foot,
and still hanging over the toe impressions (see middle photo
at left). Numerous
theropod tracks of variable quality are also found in this area
also, including some of the best preserved specimens in the
Paluxy. One is
on the edge of a cracking section of the track bed and soon may be
lost to erosion, however, a mold was made of this track a few years
ago.
Many visitors ask: "Why are the tracks preserved in the riverbed,
and why haven't they eroded away after millions of years?" First,
when the tracks were made, there was no Paluxy river--just a
vast mud flat. After the tracks were made in moist, limy
mud, they probably dried out for a brief time, then were reburied
with a somewhat contrasting sediment, followed by yet additional
layers. There they remained, gradually turning to limestone over
geologic history, until they were re-exposed in modern times when
the erosive action of the Paluxy River, and in some cases human
excavators, removed the overlying rock layers.
