210-Million-Year-Old Footprint Fossils Suggest 2 Distinct Trisauropodiscus Morphotypes

Animals reportedly made the ancient birdlike footprints found in Lesotho from two categories. One was from dinosaurs, while the other was similar to those of modern-day birds.

Birdlike Footprints in Lesotho

Scientists have been examining some birdlike footprint fossils from Africa that date back approximately 210 million years more closely.

Since fossils for even the earliest bird progenitors don't appear for another 60 million years, these footprints remain somewhat of a mystery.

Although these footprints have existed for a long time, a team from the University of Cape Town in South Africa intended to conduct a more thorough examination of the fossils, which were obtained from four different locations in the area.

With a focus on the data discovered at the Maphutseng site, an 80-meter (262-foot) stretch of tracks, the researchers were able to distinguish between two distinct types of footprints or morphotypes, falling into the Trisauropodiscus category designation originally given to birdlike, three-toed footprints.

"Our findings suggest that there are two distinct Trisauropodiscus morphotypes, one of which resembles footprints made by birds," geologists Miengah Abrahams and Emese Bordy wrote.

According to the researchers, the first morphotype had broader, longer feet with closer-spaced toes. These footprints resemble another preserved footprint known as Anomolepus, which scientists believe belonged to a particular kind of dinosaur.

In contrast, the second type of footprints were typically half as large and broader than taller. They also had more slender toes. This morphotype is more enigmatic, although it more closely resembles contemporary birds.

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Controversy Behind Birdlike Footprints

Dr. Miengah Abrahams, a lecturer in geological sciences at the University of Cape Town in South Africa and lead author of the new study, said the footprints were initially identified as the earliest birdlike tracks. However, considering its age, she believed dinosaurs likely made the footprints.

The animals behind the mysterious tracks have remained unknown, so the experts haven't established their relationship with birds. Abrahams also noted that not all of the footprints were "birdlike."

There are no known fossil creatures from this area or era that exactly match the footprints. Their origins may be in the evolution of birdlike feet in cousins of dinosaurs or other reptiles. It's adding to the understanding of morphological diversification in this incredibly important period in archosauria, said Dr. Julia Clarke, a professor of vertebrate paleontology at the University of Texas at Austin, who was not involved in the study.

Evolutionary adaptations were booming in archosaurs - the ancient reptile group that includes dinosaurs, pterosaurs, and crocodilians - at the time. Per Clarke, trisauropodiscus tracks were stamped into the mud. For this reason, finding evidence of birdlike feet in an unidentified group member is intriguing.

Trisauropodiscus demonstrates how the anatomy of the feet is substantially older, a feature that contemporary birds and other Late Mesozoic archosaurs have in common, Abrahams added. The recent study advances their understanding of the development of birds and dinosaurs.