Notice the rougher surface layer here. This may be the imprint of a blue-green algal mat (cyanobacteria) that covered the underlying mud. Such a mat may have protected the footprints, holding their form, until they dried and hardened. Later, softer sediments filled and flowed over them.
The print outlined with the hoop is from an Acrocanthosaurus left foot. You can see its first left footprint nearest us, then moving away, stepping right foot, then left foot on the “snail” trail at the hoop. We discuss the “snail” trails next.