Walking in the Footsteps of Dinosaurs

St. George was a Dinosaur Oasis

The red sandstone boulders used throughout Red Hills Desert Garden were excavated during construction of the office building directly east of the garden. Many contain clues to what life would have been like here during the early Jurassic period approximately 193 million years ago. At the time, the majestic Navajo Sandstone formations common throughout the region would have been massive sand dunes. However, the region around St. George was home to a large body of water that created an oasis—attracting abundant life. In fact, many tracks on display in the garden are identified as swim tracks, created by toes and tails scraping patterns in the mud.

Here are some clues to look for as you tour the garden

True Tracks vs. Natural Casts

The rocks in the garden contain either true tracks or natural casts. A true track is a footprint left by a dinosaur in soft material like sand or mud. A natural cast forms when that footprint fills with sediment, preserving the shape. The cast captures the details of the track and is often more durable than the original. Over time, both the track and cast fossilize. When excavated, it’s like removing clay from a mold: the original impression is sunken in the rock, and the cast is raised. Most of the examples in the garden are natural casts.

Foot Tracks

Paleontologists classify tracks by type and dinosaurs that existed in the area to determine possible species that made the tracks. Track types at the garden include Eubrontes, Grallator, Kayentapus and Anomeopus. Species that may have made these tracks include Dilophosaurous, Megapnosaurous and Scutellosaurous.

Swim Tracks

Think of swimming in a lake where you can just barely touch the bottom, toes scraping through the mud to propel yourself forward. This is the same way the dinosaur swim tracks formed. Look for long scrape marks in the rocks where toes or tails dragged in the mud.

Invertebrate Burrows

Scoyenia and Skolithos are both types of trace fossils that provide insight into ancient invertebrate behavior. Scoyenia consists of complex burrows or tunnels made by organisms like worms, often showing branching patterns, and is typically found in fine-grained sediments. Skolithos, on the other hand, refers to vertical burrows made by burrowing animals, often seen as straight, cylindrical tubes in sandy rocks. Both are present in many rocks displayed at the garden.