Update on the Cenomanian vertebrates from Algora (Guadalajara, Spain):new data on the faunal transition between the Early and the Late Cretaceous of Europe

International audienceThe largest concentration of vertebrate macroremains for the Cenomanian of south-westernEurope has been recognized at the palaeontological area of Algora (Guadalajara Province, centralSpain). The study of the taxa identified there provided new information about the palaeobiogeographyand temporal distributions of some lineages, and increased knowledge about the poorly-known transition between the Lower and the Upper Cretaceous faunas in Europe. The presenceof eight taxa was confirmed there: the lepisosteoid fish Obaichthys africanus; the helochelydridturtle aff. Plastremys lata; the bothremydid turtle Algorachelus peregrina; an indeterminate elasmosauridplesiosaur; a non-eusuchian neosuchian and a eusuchian crocodyliform; an indeterminatelithostrotian titanosaur; and an indeterminate theropod probably belonging to Abelisauridae.Recent fieldwork campaigns, performed in 2019 and 2021, provided more than 1,200 new vertebrateremains, including those of clades poorly represented so far, as well as others hithertounknown at this site. Therefore, the faunal list can be remarkably increased. In this sense, severaltaxa of Osteichthyes have been found, and chondrichthyan remains are also recognized there forthe first time. New remains of crocodyliforms, theropods and sauropods allow to analyze, in moredetail, the systematic attribution of the representatives of these lineages present in Algora. Notonly new relevant specimens of helochelydrids and bothremydids stand out among the numerousfinds of turtles (which allow a better understanding of the anatomy of the represented species),but especially the discovery of the partial skeleton of a relatively large cryptodiran sea turtle(including, among other elements, the carapace, with more than 1 meter in length, and the skull).In addition, other lineages hitherto unrecognized at this fossiliferous locality, such as a squamatewith aquatic affinities, are identified. The main novelties in knowledge about the Cenomanian vertebratefauna of Algora are presented here, and the palaeobiogeographical implications of severalof the new finds are discussed