Complex sentence: Just inside the site entrance is a dinosaur footprint on a rock, whilst a reconstruction of the sort of dwelling used here in the Mesolithic was designed and has lasted over nine years, providing decent shelter, with the door angled away from prevailing winds.
Split into simpler sentences: Just inside the site entrance is a dinosaur footprint on a rock, and a reconstruction of the sort of dwelling that was used here in the Mesolithic. This reconstruction has lasted over nine years, and provides decent shelter, with the door angled away from the prevailing winds.