First early Eocene lizards from Spain and a study of the compositional changes between late Mesozoic and early Cenozoic Iberian lizard assemblages

摘要

Lizard and amphisbaenian fossil material is described for the first time from early Eocene localities in Spain, more specifically from Catalonia (north-eastern Iberian Peninsula). Material is fragmentary and scarce, but diagnostic enough to provide a first approach to the composition of lizard assemblages. The following taxa are recorded: Geiseltaliellus and a second indeterminate pleurodont iguanid; an agamid similar to “Tinosaurus”; an indeterminate gekkotan; a scincoid, possibly scincid lizard; a lacertid similar to Dormaalisaurus; an indeterminate amphisbaenian; a glyptosaurin glyptosaurine (cf. Placosaurus); an indeterminate anguine; and, finally, an indeterminate “necrosaur.” The studied localities range from the MP8+9 to the MP10, and thus complement the only previously known lizard locality of the Iberian early Eocene, the Portuguese locality of Silveirinha, which corresponds to the MP7. An analysis of the composition of these new assemblages suggests a great amount of homogeneity through the different levels of the early Eocene, and also between Iberian and contemporaneous assemblages from the rest of Europe. The lack of an Iberian Paleocene record for lizards strengthens the importance of the study of early Eocene assemblages because these are the only ones available for comparison with Cretaceous associations, providing critical information on the changes in composition between Mesozoic and early Cenozoic lizard faunas related to the K/Pg extinction event.