Taphonomy strata of the
Iberian Ranges As a
Konservat-Lagerstätten, the preservation is exceptional. This may be a result of three factors: Microbial mats, Obruption and Stagnation. Microbial mats may be responsible for the preservation of soft tissue in many fossils from Las Hoyas, like
Pelecanimimus' crest. The iron carbonate depositions, a result from bacterial metabolism which covered the dinosaur's crest enhanced the preservation of those soft tissues. Evidence of these mats comes from the studies on microfacies and the fossils themselves. Obruption is notable in the formation, due to the presence of highly articulated specimens. From actuotaphonomy studies on several different organisms it can be estimated that the burial of most entities was quick.
Concornis may have been buried in less than 15 days, after a period of sub-areal exposition.
Paleoenvironment Las Hoyas was an inland lacustrine environment which presents an important aquatic and terrestrial
flora (with many specimens of
Charophytes,
Montsechia,
Weischelia or
Frenelopsis) and diverse
fauna, with specimens of at least five or six
phyla:
arthropods,
molluscs,
chordates and many
vermiform soft bodied animals which might be
Nemertines or
annelids. Among
vertebrates the most abundant and diverse group are
fish. The presence of mostly articulated skeletons, exceptional preservation of tissue and lack of any other signs of transportation may indicate that these are demic and autochthonous entities (meaning that they lived and died in the same place where they fossilized).
Crocodylomorphs are the most abundant
amniotes from Las Hoyas.
Dinosaurs from Las Hoyas (avian and non avian) are unique in many ways. The first
ornithomimosaur dinosaur described in Europe,
Pelecanimimus polyodon, shows some characters previously unknown in these dinosaurs which enhanced the knowledge on the evolution of the group, such as a high number of teeth.
Concavenator corcovatus presents two unique features: very tall neural spines on the vertebrae near the hip, which look like a hump, and a structure on its forearm, which if homologous to
quill knobs would push back the origin of feathers earlier in theropod evolution. Las Hoyas
birds are
enantiornithes, the most diverse Cretaceous bird clade, which became extinct at the end of the period.
Iberomesornis romerali shows both derived ("avian") and primitive ("dinosaurian") characters. Within the derived characters we can underline the presence of a pygostile, although it is still very large compared to that of modern
neornithines and the presence of a quilled sternum.
Eoalulavis hoyasi shows the first report of an
alula or "bastard wing", which means it had a flight manoeuvrability analogous to that of modern birds.
Research The Las Hoyas site has been studied for more than two decades by researchers from the
Universidad Autónoma de Madrid, the
Universidad Complutense de Madrid and the
National University of Distance Education, in collaboration with the
Museo de las Ciencias de Castilla-La Mancha, which is responsible for the fossil record from the area. == Fossil content ==