Vertebrate microfossil diversity from the Tremp Formation (Maastrichtian): Contributions to evolution of the Late Cretaceous terrestrial ecosystems from the northeastern Iberian Peninsula

Abstract

The present PhD dissertation deals on the diversity of the small- and medium-sized vertebrates from the latest ecosystems of the Late Cretaceous (Maastrichtian) represented in the fossil record of the Tremp Formation (Catalonia, Spain). The studied microfossils belong to chondrichthyan, osteichthyan, amphibian, squamate and crocodilian groups. Regarding fishes, the results show a low diversity of chondrichthyans, but a diverse assemblage of osteichthyans representing a good example of the teleost diversification during the end of the Cretaceous. Likewise, the fossil remains referred to osteoglossiforms and cypriniforms are the oldest evidence for these groups in Europe and in the world, respectively. The results of this thesis also point to a diverse assemblage of amphibians and squamates, among which the gekkotan fossil is the only occurrence of this group in the Mesozoic record of the Iberian Peninsula, and one of the little evidence in Europe. The fossil record of crocodylomorphs is mainly composed of shed teeth from different notosuchian, neosuchian and eusuchian clades. Moreover, two new species of the genus Allodaposuchus were erected based on two partial skeletons. These two specimens have been relevant to know the postcranial bones of this extinct crocodilian group. These species have also allowed us to propose new hypotheses about the ecological diversity of allodaposuchids and the evolutionary history of living crocodiles. Besides of systematics and taxonomic contributions, the study of the fossil microvertebrates has enabled us to assess the palaeoecology of the aquatic and continental environments from the Maastrichtian of the Iberian Peninsula, as well as the origin and biogeographical relationships of the Maastrichtian vertebrate faunas. These new data are contributing to reconstruct the ecosystems from the northeastern Iberian plate during the end of the Cretaceous; and to understand the dynamics and evolution until the massive extinction event in the Cretaceous-Palaeogene boundary.

Date of Award	7 Feb 2017
Original language	Undefined/Unknown
Supervisor	Àngel Galobart Lorente (Director), Josep Oriol Oms Llobet (Director) & José Manuel Marmi Plana (Director)