One of the great things about all the recent rains is the
muddy areas along the edges of streams.
I know, I know… it’s not really that great if you’re walking through it
but what if something else was walking around?
Muddy stream banks are great recorders of critter activity. Rick and I recently went down to the
Navasota River along Sulphur Springs Road to look for birds. Well, Rick was looking for birds. I get easily distracted when I look
down. We found several well-preserved
tracks along the muddy river bank. Some tracks are obvious, like
dog or raccoon tracks. From these tracks
we know someone was walking their dog earlier in the day. And sometime before that a raccoon left his
little human hand-like prints while bringing his meal down to the water to be
washed.
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| Dog tracks (upper left) and raccoon tracks (lower left) along the muddy banks of the Navasota River. |
Great Blue Heron tracks are also pretty cool to find. That’s my foot for scale in the picture below. We all know they’re big birds but knowing
they’re almost eye-to-eye with me is a little disconcerting! These tracks are easy to ID because there’s
nothing else that big around here regularly that could make them.
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| Great Blue Heron track (with my foot for scale!) along the Navasota River. |
Other tracks are a little harder to figure out. See the picture below. Are these beetle tracks? Worm traces?
Obviously they were small critters that don’t mind crawling on ripples
in the mud near a river.
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| Insect tracks and ripples in the mud along the Navasota River. |
And don't forget plants! While plants don’t actually walk they can
leave traces in sediment. This grass
from Lick Creek Park left circular traces in the sand when the wind blew. This is one case where the critter that made
the trace is actually in the picture!
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| Grass blown by wind leaving circular traces in the sand along Post Oak Trail at Lick Creek Park. |
Modern tracks are easy to
deal with. For the most part, we know
what made them and we can see the environmental conditions those tracks were
made under. So what about ancient
traces? Rick and I went to Leander, TX,
to see some dinosaur tracks along the South Fork San Gabriel River. Ancient tracks are a bit harder to figure out
sometime. Ok, not dinosaur tracks! Those are obvious! The tracks below are about 100 million years
old and made by a dinosaur called an Acrocanthosaurus.
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| Dinosaur tracks along the South Fork San Gabriel River, Leander, Texas. |
So what can these tracks tell us? Well, just how modern tracks are created, the
dinosaur had to be walking in soft sediment.
Also, in order to be preserved, the tracks had to be covered
rapidly. Ever seen footprints at the
beach? Usually they’re gone by the next
day because the tide comes in and washes them away. The rocks the dinosaur tracks are preserved
in is a fine-grained limestone. I also
found mudcracks and an oyster fossil nearby so the area around Leander, Texas, 100 million years ago was a muddy environment with shallow water that periodically dried up.
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| Mudcracks, ancient (left photo) and modern (right photo) along the South Fork San Gabriel River, Leander, Texas. |
Unfortunately, you won’t find dinosaur tracks in Brazos
County… our rocks are too young! What
tracks can you find around here? Check out
the websites below for with common tracks from Texas Parks and Wildlife.
From modern tracks to ancient tracks, there is a lot we can
understand by taking a look down once in a while. Sorry Rick and all those birds in the trees!
References:
This article describes the dinosaur tracks in Leander,
Texas.
More on the Glen Rose Formation:
Animal Tracks PDFs from Texas Parks and Wildlife:
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