The Cenomanian vertebrates from the Algora site (central Spain): New information on the faunal replacement between the European Lower and uppermost Cretaceous faunas
Résumé
The fossil site of Algora (Guadalajara Province,
central Spain) represents the main concentration
of Cenomanian vertebrate macroremains in southwestern
Europe. Fishes, plesiosaurs, turtles, crocodiles,
theropod and sauropod dinosaurs are identified.
Knowledge has been remarkably increased as a result
of the study of several recently found specimens.
Thus, the previous systematic identification of the
fishes from this site is refuted, being reattributed to
a single species, shared with the African record. The
systematic identification of the primitive turtle (i.e.
Solemydidae) from this site can be justified for the
first time, the previous attribution being also refuted.
The presence of carcharodontosaurid theropods in
Algora cannot be supported, a basal representative
of Allosauroidea being identified. The crocodile
remains allow justifying the presence of Eusuchia. The Algora fauna is composed of some lineages present
in the European lower Cretaceous record, some of
them being scarce at those levels (e.g. eusuchians
and titanosaurs), as well as by clades originated in
Gondwana, and not recognized in pre-Cenomanian
sites of this continent (e.g. gars, bothremydids).
Therefore, the faunal composition of Algora markedly
differs from that of the European Lower Cretaceous
levels, showing more affinities with that of the
uppermost Cretaceous. Thus, the faunal replacement
identified when the European Lower and uppermost
Cretaceous continental vertebrate faunas are compared
had already occurred, at least for some lineages, before
or during the middle Cenomanian. The climate changes
that took place at the end of the lower Cretaceous to
the lower Cenomanian are identified as factors that
conditioned this faunal replacement.