The Lagosteiros Natural Monument, near Cape Espichel, in

Sesimbra Sesimbra () is a municipality of Portugal, in the Setúbal District, lying at the foothills of the ''Serra da Arrábida'', a mountain range between Setúbal and Sesimbra. Due to its particular position at the Península de Setúbal, Setúbal Bay, ...

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

, is a Portuguese protected area created in 1997, consisting of

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

trackway ichnites.

Geologic context

The Lagosteiros site is included within the

Lusitanian Basin The Lusitanian Basin is a rift Depression (geology), basin remnant located on both the mainland and continental shelf off the west-central coast of Portugal. It covers an area measuring and extends north-south from Porto to Lisbon. The basin var ...

and is the most recent dinosaur track site in the Cabo Espichel region, having been formed approximately 130 to 120 million years ago, during the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

, when the western margin of Portugal had flat,

marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...

y and muddy terrains. Those soft

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

s eventually

lithified Lithification (from the Ancient Greek word ''lithos'' meaning 'rock' and the Latin-derived suffix ''-ific'') is the process in which sediments compact under pressure, expel connate fluids, and gradually become solid rock. Essentially, lithificati ...

into

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

strata In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...

, thus preserving the footprints of the dinosaurs that there roamed.http://monumentos.gov.pt/Site/APP_PagesUser/SIPA.aspx?id=30891 monumentos.gov.pt: Jazida de icnofósseis dos Lagosteiros

Tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

motion in the region has rotated the strata from its original horizontal layout to a north- dipping

attitude Attitude or Attitude may refer to: Philosophy and psychology * Attitude (psychology), a disposition or state of mind ** Attitude change * Propositional attitude, a mental state held towards a proposition Science and technology * Orientation ...

of 45°.https://geoportal.lneg.pt/pt/dados_abertos/cartografia_geologica/cgp50k/38-B GEOLOGICAL MAP OF PORTUGAL, 1:50 000 SCALE, SHEET 38-B - SETÚBAL (1994)

Natural monument description

Location

Monumento Natural dos Lagosteiros panorama

Of great natural beauty, the Lagosteiros Natural Monument and its tracks are nowadays located on, and immediately adjacent to, the edge of the

cliff In geography and geology, a cliff or rock face is an area of Rock (geology), rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. ...

that defines the northern side of the ''Lagosteiros Bay'', and approximately 1400 meters away NNE from Cape Espichel. The tracks are visible in a stratum of yellowish-brown limestone.
Due to the strata's northwards dip, and the cliff walls that further rise above the site to the east, the best time of the day for visiting is during the afternoon, when the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

strikes the rock bed at a good angle, shading the tracks in contrast with the illuminated rock, as seen in the photographs here. During a short period around the

winter solstice The winter solstice, or hibernal solstice, occurs when either of Earth's geographical pole, poles reaches its maximum axial tilt, tilt away from the Sun. This happens twice yearly, once in each hemisphere (Northern Hemisphere, Northern and So ...

, the Sun will not rise high enough in the sky to illuminate the natural monument, leaving it shaded.

Ichnology

Tracks of

bipedal Bipedalism is a form of terrestrial locomotion where an animal moves by means of its two rear (or lower) limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' ...

dinosaurs,

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

s and herbivores are visible on the surface, in different orientations. Among the numerous tracks, a long main trackway stands out with large footprints, attributed to a bipedal animal. An approximately rectangular mark is visible on the side of this trail, possibly a

tail The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...

mark. Theropod tracks feature the characteristic

tridactyl In biology, dactyly is the arrangement of digits (fingers and toes) on the hands, feet, or sometimes wings of a tetrapod animal. The term is derived from the Greek word () meaning "finger." Sometimes the suffix "-dactylia" is used. The derive ...

footprints, pointed at the ends of the digits.

References

{{Protected areas of Portugal Protected areas of Portugal 1997 establishments in Portugal IUCN Category III Geology of Portugal