These footprints were found at several locations in southern Africa. They were recently determined to be the oldest bird tracks ever found.
A recent study shows that millions of years before birds appeared, there was a mysterious animal that walked with bird-like legs.
Archaeologists have discovered fossilized footprints with three toes dating back more than 210 million years in a layer of ancient soft mud.
These footprints were found at several locations in southern Africa. They were recently determined to be the oldest remains of birds ever found, much older than the earliest known fossils of birds dating back about 60 million years.
“Judging by the age, they were probably made by dinosaurs,” said Dr. Miengah Abrahams, Lecturer in Geological Sciences at the University of Cape Town in South Africa and lead author of the study.
Theropods, including Tyrannosaurus rex, were a group of bipedal carnivores that possessed feet with three toes on each side.
But among these newly discovered tracks, there are some that differ from typical dinosaur footprints. They spread less, are wider, and have significantly longer toes. These features make the footprints more similar to those of birds, Abrahams told CNN.
Illustration of a fossilized dinosaur discovered in Patagonia, Chile, June 8, 2023. (Photo: AFP/TTXVN)
However, these are still just footprints, so the relationship of the animal that created them to the bird is still unclear.
Researchers say the footprints may belong to a species that serves as a missing link in bird evolution. It’s also possible that they belong to reptiles unrelated to avians, but have evolved independently with bird-like feet.
These footprints were discovered in the mid-20th century, and the species that created the footprints was scientifically named Trisauropodiscus by French paleontologist Paul Ellenberger. They belong to a group of animals that are only studied through trace fossils, not fossils from the body. These fossils are often called invertebrate fossils.
It is thought that seven species of animals are related to the traces left by the Trisauropodiscus. For decades, scientists have debated the group’s kinship with birds. According to researcher Abrahams, Ellenberger could have assigned many tracks of different shapes to one animal, and not all of them were bird-like.
Furthermore, the shape of the footprints is also different, depending on the types of materials the animal steps on. This can make it difficult to determine the physical characteristics of an extinct animal when boneless fossil tracks are the only clues it left behind.
Dr. John C. Julia Clarke, Professor of Vertebrate Paleontology at the University of Texas, USA, said that by the time Trisauropodiscus traces were buried in mud, an adaptive evolutionary process was exploding in the group. Ancient reptiles include dinosaurs, pterosaurs and crocodiles. So it was exciting to find evidence of a bird-like foot in a mysterious member of this group.
“The footprints do not exactly match any animal fossils known from the area during this time period. They could belong to other reptiles or relatives of a dinosaur that evolved to have bird-like feet,” Clarke said.
The researchers’ investigation began in 2016. The team “followed in Paul Ellenberger’s footsteps” but used modern research standards.
During a trip to Maphutseng, a fossil-rich site in Lesotho, South Africa, the team found several bird-like tracks from the Triassic Period. “It took us a long time to realize we were looking at Trisauropodiscus,” Abrahams said. Our initial impression was that these tracks really looked like bird feet and we knew we needed to investigate them further.”
This requires researchers to survey fossil sites, analyze photos, make sketches, and create 3D models of the footprints.
A fossilized footprint. (Source: Wikipedia)
Scientists looked at 163 tracks and divided them into two types or morphologies based on their shape.
Morphotype I group was determined to be non-bird-foot-like. They are slightly longer than they are wide, with rounder, stronger and less flared toes. They also have a “heel” created from the pads of the third and fourth toes, Abrahams said.
Morphotype II group has smaller foot grooves, greater width relative to length, with slimmer toes. This shape and width closely resembles bird tracks from the Cretaceous Period (145 million to 66 million years ago). It was the wading bird Gruipeda, another invertebrate fossil animal, also known only through footprints. And overall, the Morphotype II group’s tracks closely resemble those of modern birds, the scientists said.
However, the oldest fossil evidence of paravians – the group of dinosaurs that includes the earliest birds and their closest relatives – dates from around the mid-Jurassic period (201.3 million to 145 million years ago).
Therefore, the foot prints belong to the Morphotype II group, dating back at least 210 million years. It can be hypothesized that these bird-like feet are even more ancient./