A trackway is a preserved sequence of impressions left by an organism as it moved across a surface, providing a fossilized record of its activity. These fossilized traces, often footprints, offer a direct glimpse into the past, unlike body fossils which are the remains of the organism itself. Paleontologists study trackways to gather information about ancient life forms and their interactions within prehistoric environments. They provide tangible evidence of an organism’s presence and movement, making them valuable tools in understanding Earth’s history.
How Trackways Form
Trackways form when an animal steps onto soft sediment, such as mud or sand, leaving an impression. Consistency is important; if too hard, no print forms, but if too soft, the impression might collapse. For preservation, these impressions need rapid covering by another layer of sediment, protecting them from erosion or destruction.
Over time, the layers of sediment undergo lithification, compacting and cementing into solid rock. This process turns the soft impressions into durable fossils. Sometimes, the material filling the original track can also harden, forming a natural cast that provides a three-dimensional replica of the foot, complete with potential skin impressions.
Unveiling Ancient Life
Studying trackways offers a window into the locomotion of ancient creatures. By analyzing the spacing between prints, scientists can estimate an animal’s stride length and speed. The arrangement of footprints also reveals an organism’s posture, indicating whether it was bipedal, like many dinosaurs and humans, or quadrupedal.
Trackways also provide insights into the behavior of ancient species. Parallel tracks by multiple individuals of the same species can suggest herd or pack behavior, similar to modern wildebeest. Evidence of different species’ footprints together can indicate interactions, such as a predator stalking its prey.
Beyond individual movement, trackways can reveal details about the ancient environment. The presence of “swim” tracks suggests that a site was covered by deep water. Tail drag marks can indicate whether an animal dragged its tail or held it aloft. Analyzing the sediment type surrounding the tracks also provides clues about the ancient landscape, like a muddy shoreline or sandy riverbed.
Scientists can also infer aspects of an animal’s anatomy from its trackway. The size and shape of individual footprints, along with impressions of digits or claws, reveal foot structure and overall body size. This information can help identify the group of dinosaur that made the track, even if the exact species is difficult to determine without associated skeletal remains.
Notable Trackway Discoveries
The Laetoli trackway in Tanzania is a renowned discovery, preserving the footprints of early human ancestors. Dating back approximately 3.6 million years, these hominin footprints were preserved in volcanic ash that solidified after rain. These tracks provide direct evidence of bipedal locomotion in these ancient hominins.
In 1997, a significant find occurred at a limestone quarry in Ardley, England. This site yielded dinosaur trackways, believed to be from large sauropods like Cetiosaurus and the carnivorous theropod Megalosaurus. A 2024 discovery at the nearby Dewars Farm Quarry in Oxfordshire, dubbed a “dinosaur highway,” uncovered over 200 distinct tracks, with the longest continuous trackway extending over 150 meters. This provided further insights into Jurassic period dinosaur movements.
In Alberta, Canada, 76-million-year-old trackways provided evidence of mixed-species herding behavior among dinosaurs. These tracks include those of ceratopsians, such as Triceratops, an ankylosaurid, and two Tyrannosaurus rex trackways, raising questions about predator-prey dynamics. These discoveries offer insights into social interactions and group movements in prehistoric ecosystems.