Lindsey Ravilious, a fourth year undergraduate student studying for an MSc in Geoscience at Royal Holloway, University of London in the UK, has recently completed a project entitled Tracking Dinosaurs as part of her degree course and has supplied details for The Resident on her findings in the Algarve.
Always keen on paleontology, the study of ancient life, I was drawn to Salema in the vila do Bispo region during a holiday where I learned that dinosaur footprints (tracks) had been previously discovered.
After intensive research, I planned my own investigation to determine some key characteristics and identities of these dinosaurs.
Praia da Salema lies in the Algarve Basin, which formed during the Mesozoic.
In August 2006, I studied two separate dinosaur trackways in two separate levels of Lower Cretaceous limestone (Barremian in age – 124-119 million years ago), one in the east cliffs and one in the west cliffs of Praia da Salema. The tracks showed various levels of preservation due to erosion and weathering by the sea, wind and other forces of nature.
By careful measurement and study of the tracks and by analysing the rocks in which they lie, I concluded some fascinating details of these dinosaurs and the environments in which they lived.
Seven tracks/footprints (approximately 23cm in length) were found in the east cliffs (these rocks are slightly younger than those which comprise the west cliffs, but they are still Barremian in age). These tracks were made by three individual dinosaurs, one heading south and two north-east.
These were bipedal (two-legged), tridactyl (three-toed) theropods (carnivores or meat-eaters). They had sharp claws at the ends of long, narrow digits, V-shaped heels and held their tails in the air. The height to their hips (hip height) ranged from approximately 74cm to 1.13m. One individual was walking at approximately 3.5km/hr. I also found bivalve fossils, suggesting a lagoon environment.
Twelve larger tracks (approximately 42cm in length) were found in the west cliffs. These were made by one bipedal, tridactyl Iguanodontid (large ornithopod). This herbivore or plant-eater was walking north-eastwards.
These tracks had short, rounded digits with no claws and U-shaped heels. The footprints were slightly rotated inwards indicating the dinosaur was pigeon-toed, this meant the dinosaur’s hips swivelled with each stride.
The tracks were aligned almost one in front of the other forming a straight line, this meant the dinosaur stood upright with its legs positioned directly underneath its body. Its hip height was approximately 2.48m and had an approximate body length (from top of its head to tip of its tail) of six to seven metres. It was walking at a leisurely speed of approximately 1.66 km/hr.
The tracks were found in a mudstone limestone, which means the dinosaur walked on a very fine grained, muddy sandy substrate, possibly close to a coastal shoreline or on the edge of a lagoon.
Background
• Dinosaur: word derived from Deinos meaning terrifying and Sauros meaning lizard.
• Dinosaurs ruled the earth during the Mesozoic era, between 245 and 65 million years ago. The Mesozoic era comprises the Triassic, Jurassic and Cretaceous periods.
