A Story Standing Millions of Years at Dinosaur Valley State Park in Glen Rose, Texas

Texas Dinosaur Valley State Park
Glen Rose, Texas

Dinosaurs inspire a wide range of imaginative thoughts and ideas. For many, our minds take us to dinosaur films such as Jurassic Park, The Lost World, Ice Age, The Land Before Time, The Croods, or Disney’s Dinosaur. For others, ideas of gargantuan size chicken ancestors with razor sharp teeth and scaly skin arise (plus little T-rex arms!) in our minds highlighting how foreign they seem to our present day version of animals. Being able to witness such distinct features such as the Glen Rose tracks welcomes us to stretch the versions of time and the earth we know to incorporate different stories than the plot we humans participate in today.

A destination that should be on any geologist, paleontologist, rockhound, or general dinosaur enthusiast’s bucket list is Dinosaur Valley State Park in Glen Rose, Texas.

Located just over an hour away from Dallas, Texas, Dinosaur Valley State Park is a natural riverbed where a series of dinosaur tracks have been perfectly preserved from an ancient chase scene and a unique series of events that fossilized their tracks into permanent history.

The Tracks Discovery

The Dinosaur Valley tracks were formed in shallow, tidal flats composed of sticky, lime mud brought in by stormy weather around 110 million years ago (mya). Then eroded upland material brought downstream by storm events, causing heavy river flow, was quickly transported and covered the tracked mud with soft silt and clay particles. In general, the smaller the grain size of the soil, the farther it traveled from its source. The tracked layer in the limey mud eventually hardened into limestone and the silt/clay layer on top eventually hardened to form marl and shale.

Over time, the softer marl and shale were eroded by the Paluxy River, which then exposed the harder, more-erosion-resistant limestone below. The fully preserved molds of dinosaur feet, perfectly shaped, are extremely rare! Even though many of the track traces were revealed and visible by natural means, many of the tracks found in the area were unearthed by careful, dedicated geologist and volunteer hands to preserve the original form as much as possible.

Please see the attached video for more information about the tracks and the park’s history.

The Time Period

A quick review, the universe is understood to be approximately 13.8 billion years old. The Earth is generally agreed to be about 4.6 billion years old. Organisms arrived on the scene 2.5 billion years ago. Before dinosaurs, there were amphibious reptiles, soft organisms, and numerous bug-like creatures. The most common fossils of this time are trilobites, also recognized as the cockroach of the sea because a multitude of variations of the plated sea bug have been found and recorded. Mobile animals/dinosaurs on land have been around for roughly 300 million years starting in the Permian Period.

Even though most of us think of the Jurassic period of history as the timeframe of dinosaurs, the Cretaceous is center stage today! If you look at the chart below you’ll see dinosaurs lived during the Permian, Triassic, Jurassic, and Cretaceous periods in order of oldest to youngest. Various sets of dinosaurs and organisms roamed the land and seas for over half a billion years, with each set divided by a total of five catastrophic extinction events! Talk about putting our human fear of climate change into perspective; five other global meltdowns have already occurred. Hopefully we make it through this round of change unlike the dinos in Texas.

The tracks found in Glen Rose were from the Cretaceous Period. This is also the same period that had the massive extinction event (also known as the KT event) when supposedly a meteor struck the Earth and wiped out 80% of life. Somehow though, nature found a way to evolve through the tumultuous event and thrive.

The Types of Dinosaurs

Sauropod Tracks

Sauropod tracks look like bathtub-sized elephant-like tracks from the feet of a large herbivorous dinosaur with an extensively elongated neck that stands on four legs. Sauropods are part of the Astrodon genus where many averaged 20 meters in length (66ft long) and 9 meters in height (30ft tall or similar height to a 3-story building) and weighing 20 metric tons (equivalent weight to a loaded school bus or whale shark). We recognize these dinosaurs are similar to classic images of Brontosaurus like in the 1985 film Baby: Secret of the Lost Legend, though these specific tracks at Glen Rose are of a distant relative of the Brontosaurus called a Pleurocoelus.

The Pleurocoelus dinosaurs lived approximately 95 to 112 million years ago and can be pronounced like the following “plu-er-oh-cell-us”

Theropod Tracks

Theropod tracks are mid-sized, distinct, with a three-toed pattern from the foot of a large carnivorous dinosaur with short mobile hands that stand on two hind legs making it bipedal. Bi- means two, -pedal is related to foot movement like on a bike, therefore we have two-footed creature. Theropods are part of their own Clade, often referred to the ancestors of birds like an ostrich or a chicken, though this specific track is believed to have been made by an Acrocanthosaurus. Acrocanthosaurus are one of the largest known theropods reaching 11.5 meters in length (38 ft long) and 4 meters in height (13ft tall) and weighing up to 6.2 metric tons (equivalent weight to an African Elephant). We recognize these dinosaurs are similar to a Tyrannosaurus Rex, though in our case in Glen Rose this Acrocanthosaurus had a higher neural spine, likely for a hump, ridge, or short sail on its back, and a slightly more angled head. The head was just a tad shorter than a T-Rex skull, though these predators were just as vicious and the apex predator of the time and region.

The Acrocanthosaurus dinosaurs lived approximately 110 to 113 million years ago and can be pronounced like the following “a-krow-kan-thuh-saw-ruhs”

The Event

Over time the tectonic plates, or puzzle-like pieces of the earth’s crust, have rearranged. The below image shows the general configuration of the plates and oceans during the Cretacous period when the Glen Rose dinosaurs roamed. Amazingly, in this diagram, Antarctica and Australia are still connected. India has a far distance to go until it rams into the Eurasian continent meaning there were no Himalayan mountains yet, and effectively the Pacific ocean was much wider since all the continents were closer together. Ahaha! Plus we can see that South America and Africa used to fit together in a much more snuggly fashion. It is hard to find the North American continent because it is partly underwater aside from the two coasts boasting the Appalachian mountains in the East and the Rocky Mountains in the West.

There was a shallow ocean called the Western Interior Seaway that ran down the middle of North America covering Central Canada, Montana, Wyoming, the Dakotas, through Texas and down over a large part of Mexico and Central America. Sea level was much higher, as we can see, with the North Atlantic and Pacific oceans connecting with seawater covering most of Central America. There was also very little ice on Earth at the time because all the water on the Earth is moved around through time in varying forms, such as in liquid form like in oceans, lakes, rivers, and aquifers or in solid form such as with snow and ice. Back then it was too hot to have snow and ice caps. In the Cretaceous temperatures were 5°C–10°C (40°F-50° F) higher than today, and sea levels were 50–100 meters higher. In general, higher temperatures mean the atmosphere can hold more water, so it was generally more humid as well, which is why the time period is characterized as having a greenhouse climate.

The confounding Cretaceous allowed most of the State of Texas to be underwater with barrier reefs located west of Houston that ran all the way into current day Mexico. During the time, Llano County and Texas Hill country was actually a series of islands called the Llano Islands, now referenced as Llano County or the Llano Uplift near Austin, Texas. Dinosaur Valley State Park and Glen Rose at the time period were coastal, low, tidal flats, i.e. beachfront property. As a disclaimer, it is hard to be exact with diagrams and the one below makes almost all of Texas to appear underwater, but the sea levels rose and fell many times by a few meters in magnitude in a cyclical pattern during the Cretaceous, and this diagram is showing a higher sea level snippet in time.

The Local Area

The Lower Glen Rose Formation tracks in the park and its famous sediment sequence used to be a seashore. Distinct habitats line up in order as one moves inland from the sea. On the sea edge, it had sandy barrier shoals less than a mile offshore; then a quiet lagoon protected from waves; brackish marshes filled with a combination of fresh and salty seawater; and a wooded floodplain formed by deltas with sediment that was carried downstream from the mountains.

Such as today where Texas coastal regions were subject to tropical storms and hurricanes, what seems like a peaceful place to enjoy some paleontology now was once a moment of disaster for these dinosaurs and all life in the area. Around 110 million years ago (mya), a few days before the footprints were made a tropical storm came in beyond the barrier islands and leveled the plant-rich marshes with heavy flooding, covering the sea boundary with limey mud. This is the limey mud layer through which the small group of vegetarian sauropods journeyed in search of food only to be followed by their menacing carnivorous theropod enemies. Then shortly after, terrestrial clay, from higher elevation areas, sediment was carried by waterflow and filled in the lime mud prints the dinosaurs left behind.

Below, the pictures exhibit the higher sea level and the narrow-gated, three-toed footprints of the carnivorous Acrocanthosaurus as it smelled and searched for food and shelter. The photo below of the little boy in the Pleurocoelus foot print is from when the tracks were discovered and uncovered in 1940 by workers employed by the Works Progress Administration (WPA), which provided employment to people who needed work during the Great Depression.

The Rarity of the Event

Sparsely do geologic conditions occur in such a serendipitous order and time frame to provide the order of events to safely contain the evidence of life. That is one of the biggest reasons why the tracks are so SPECTACULAR! From a geologic and soils perspective, this order of events with the storm, prints, and clay infill sediment is special to witness. If another type of river carried more sand, which is larger in grain size, than silt and clay as the infill medium there would not be the same level of preservation because as it hardened it would have turned into sandstone. Sandstone is much more weather resistant and is harder to erode meaning the tracks would not have been revealed as easily, or even at all until farther down the timeline. This explains a little about how special this outcrop of geologic formations and series of events is and how lucky we are to be able to see the prints at this random moment millions of years later. In a couple thousand years, the river flowing on top of the prints will likely erode away the forms and the dramatic story will be lost to the mystery of time. Luckily though, sections of the tracks have been cut out and placed in museums in Texas, New York, and DC for preservation. Don’t worry though, there are still plenty of tracks to see when you visit the fun and activity-filled area.

If you would like to read about a more robust geologic analysis of the tracks documenting the environment at the time of track formation please read on with the underlined link.

The Vastness of the Park

Dinosaur Valley State Park can be a one day visit or a one week trek, this 1500 acre scenic park contains not only numerous sites to see Dinosaur tracks, but also contains camping areas, picnic areas, hiking & mountain biking trails, horse riding, swimming, fishing, 1 gift shop, 1 museum, and a wonderful river to paddle on. This State Park brings the majority of the traffic to the area of Glen Rose, and Dinosaur Valley State Park has over 5 dinosaur footprint sites each containing a full series of steps from either the Pleurocoelus (Sauropod), Acrocanthosaurus (Theropod), or both. Due to the wide range of water depth of the Paluxy River, late summer is advised to view the tracks in full clarity within the time when the river is most dry. In some locations, tracks aren’t always visible to the eye, and the water during some seasons can be quite cold with high levels where swimming to the site is an option. Here’s a map of the park: https://tpwd.texas.gov/publications/pwdpubs/media/park_maps/pwd_mp_p4503_094r.pdf

Nearby the Headquarters is a really great museum to learn all about the Site.

Below is a photo when you drive into the park and are welcomed by life sized replicas of the Pleurocoelus and the Acrocanthosaurus interacting. Just after these dueling dinos the trails pop up on your left hand side.

Main Track Site

The Main Track Site had both dinosaurs paired together with tracks just feet apart from each other, for us, some underwater, and some dry to see and feel.

RT Bird Site

The RT Bird Site was underwater for us though seemed to have some of the most incredible Acrocanthosaurus tracks

Ozark Site

The Ozark Site was underwater for us, and featured a gentleman fishing right next to some Pleurocoelus tracks, though is a spot with quite a few tracks densely packed together

Other Sites

The rest of the sites go by the following names

• Ballroom Site

• Blue Hole

• Denio Site
  

*note there have been rumors that further down the river more tracks are outside of the park, see below with Stone Hut Fossil Shop for a tour

DINOSAUR WORLD (Neighboring the Park)

Dinosaur World (located about a half mile from Dinosaur Valley State Park)

https://dinosaurworld.com/texas/

Dinosaur World contains over 150 life size scale replicas of Dinosaurs from all time periods, these include Euoplocephalus, Dilophosaurus, Sauropods, Theropods, and more, who all stand along a paved nature path for an overall kid friendly experience. A ‘big in Texas’ themed 7,000 square foot gift shop contains every type of dino-accessory from actual fossils, to stuffed animals, jewelry, magnets, books, movies, and more. Dinosaur World also contains other small interactive exhibits for kids to mine gems and even features a jungle gym.

STONE HUT FOSSIL SHOP (Neighboring the Park)

Stone Hut Fossil Shop (located about 2.5 miles before you reach Dinosaur World and Dinosaur Valley State Park)

https://www.facebook.com/TexasFossilHunter/ | https://busseys.net/

Owned by Morris "Buz" Bussey, an active member of the geologic and paleontology community in Texas and total character, operates a fantastic fossil and rock shop as his retirement project from the Texas oil industry. Morris spends his time either finding the best local specimens with which to stock his shop, providing paleontology tours for groups known as “fossil hunts”, or spending time greeting customers in his shop with his proud pup Clancy. The shop features many local ammonites, trilobites, petrified wood, and more.

Concluding Remarks

The wonders of Dinosaurs and their time here on this planet continue to keep us in awe. It is sites like these that are a once in a million chance of happening where there is an overlap between the tracks not being eroded today and the sequence of events that took place to form them. Though the days of the Sauropods and Theropods are long gone, our minds are consistently trying to put these fossils into proportion to what the time of the Dinosaurs was like. Who knows, with advances in genetics and themes of Jurassic Park gaining ground, we may just be face to face with these creatures in the future.