Footprints from birds bear remarkable similarity with those of dinosaurs from 200 million years ago.
Experiments with living species offer insights into the formation of fossil footprints, according to scientists from Liverpool and the US publishing today (July 1) in Biology Letters.
The team from Liverpool John Moores University, UK and Brown University, Rhode Island, used X-rays to image and measure 3-D foot motions of guineafowl walking through a variety of underfoot substrates.
Despite substantial step-to-step variability, the foot consistently moves in a looping pattern below the ground, matching the “looping motion” of dinosaur feet captured in the fossil record from the Early Jurassic period.
Succesful and versatile
“Dinosaurs were moving in very similar ways to modern birds even 200 million years- ago (many millions of years before birds evolved), even though they were quite different, having long, muscular tails, for instance,” explains Dr Peter Falkingham, a senior lecturer in vertebrate biology and researcher in the LJMU Research Centre in Evolutionary Anthropology and Paleoecology.
“The similarity of motion, and the similarity of foot shape (three-toed) between dinosaurs 200 million years ago and birds today tells us how successful and versatile that foot has been evolutionarily.”
The researchers say that when a foot sinks into the sediment, a) the sub-surface motion gets recorded, and b) the foot has to get out again. Where it exits relative to where it went in can tell us how the foot was moving.
New perspective on fossils
This paper provides a new theoretical framework and vocabulary for describing relative positions of entry and exit traces, offering a new way of studying fossil footprints.
- It’s in the loop: shared sub-surface foot kinematics in birds and other dinosaurs shed light on a new dimension of fossil track diversity was led by Dr Morgan Turner at Brown University and supported by her colleague Stephen Gatesy at Brown and Peter Falkingham in the UK.
- Learn how to find dinosaur fossils on the beach with Peter Falkingham in this BBC video.