We have travelled 67 million years back, at the end of the
Cretaceous period. The Pyrenees are just beginning to rise, the Montsec
and Sant Corneli mountain ranges are just emerging. Dinosaurs inhabit Conca
Dellà.Conca Dellà was a coastal plain open to the Atlantic ocean, protected from the open sea by littoral sand cordons. Between the inner lands and the sea, there was a quiet lagoon of salty water.
This was the setting inhabited by dinosaurs for two million years. The remains of this remote past tell us about an amazing diversity -remains of 6 different dinosaurs have been found- and the existence of an autochthonous species that, up to recent times, was absolutely unknown by scientists, the Pararhabdodon Isonensis, an ornithopod dinosaur. Lately, remains of this species have been identified in the south of France.
It is worth mentioning some palaeontological interest spots concerning the environment of the dinosaurs inhabiting these pre-Pyrenean lands:
Footprint Bed of La Posa
During the Cretaceous period, La Posa was near the coastal line -it should be noted that, at that time, landscape was very different to what it is now. There were littoral barriers limiting the open sea to the coast and, between the barrier and the inner land, there was a salty water lagoon intensely populated by different kinds of animals: snails, shells, corals, fishes, and so on.
The deposit of La Posa is constituted by more than 2,000 dinosaur footprints on a stratum of sandy land, produced in a coastal plane environment. The trails observed on the deposit lead to state that the footprints were formed in the coastal area, in the water, as confirmed by the presence of ripple marks -sedimentary structures formed by the water current action over the bottom sand- and bioturbation traces left by crabs and bivalves. This would explain why they are not very neatly preserved.
This footprint bed rises the questions of how many dinosaurs may have been there to leave such a large number of footprints and what kind of dinosaur was exactly the author of these footprints, as well as if any trail can be identified. Further thorough studies will allow us to know the answers to these questions in order to perform a more accurate interpretation.
Basturs Egg Bed
The dinosaur eggs of Basturs are situated on the roof of Arenisca d'Areny, a sedimentary sandy formation settled in coastal environments of a pro-grading nature. The sub-aerial part of this coastal area was taken by dinosaurs to set a nesting area that remained stable for a long time.
The deposit area has about 6,000 sq m and a large amount of nests may be seen there, as well as countless eggshell fragments. The presence of ripples proves that the area was a beach where dinosaurs laid their eggs for many years.
The eggs are sub-circular, with an average diameter of 20 cm approximately and a shell 1.5 to 2 mm thick. They have a peculiar structure that makes its surface rough. Many of them are grouped in sets of four to seven eggs; this means that, in many cases, the original arrangement of the nest has been preserved.
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Footprint Bed of La Posa |
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Basturs Egg Bed |
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Dinosaur eggs |
