Late cretaceous continental and marine vertebrate assemblages from the Laño quarry (Basque-Cantabrian Region, Iberian Peninsula): an update

Abstract

The vertebrate-bearing beds of the Laño quarry (Condado de Treviño) are among the most relevant sites from the Late Cretaceous of Europe. Geologically, Laño and the adjacent region are set on the southern limb of the South-Cantabrian Synclinorium (SE Basque-Cantabrian Region, northern Iberian Peninsula). The Laño sites were discovered in 1984; thousands of bones and teeth, including microfossils, have been collected during the prospection in the field and excavation campaigns. The vertebrate remains occur at two different stratigraphic horizons within a continental to shallow marine succession of Late Campanian-Maastrichtian age. The lower horizon contains the Laño 1 and Laño 2 sites, whereas the upper horizon contains the Albaina site. In the Laño sites, three fossiliferous beds (called L1A, L1B and L2) are known within an alluvial system composed mainly of fluvial sands and silts. The sedimentary structures are consistent with channel areas within an extensive braided river system. Based mainly on stratigraphic correlations, the fluvial beds of Laño are regarded as Late Campanian to Early Maastrichtian in age. These deposits have yielded a very diverse vertebrate assemblage, which consists of nearly 40 species, including actinopterygians, lissamphibians, lepidosaurs, turtles, crocodyliforms, dinosaurs, pterosaurs, and mammals. Seven genera and ten species have been erected to date in Laño. With reference to the marine vertebrate association of Albaina, it consists of at least 37 species, including sharks and rays, actinopterygians, mosasaurids, and plesiosaurs. Two genera and species of rhinobatoids (family indet.) and two new species of rhinobatids have been erected in Albaina. The fossil association indicates a Late (but not latest) Maastrichtian age. Recently, isolated turtle and dinosaur fossils have been discovered in the sublittoral beds of Albaina. The Laño quarry is one of the most noteworthy Campanian-Maastrichtian vertebrate localities of Europe by its taxonomic diversity, and provides useful information about the composition and affinities of both continental and marine vertebrate faunas from the latest Cretaceous of southwestern Europe.

Late Cretaceous (Maastrichtian) amphibians and squamates from northeastern Iberia

“…The other Campanian-Maastrichtian localities previously studied in the Iberian Peninsula represent braided river systems with channels, interchannel pools and sandflats (Laño, Astibia et al, 1990;Pereda-Suberbiola et al, 2015) and small ephemeral lakes and ponds in coastal mangrove-like (Blain et al, 2010) and Chera (Company and Szentesi, 2012)). In addition, these localities represent a timespan of about six million years, from the upper Campanian-lower Maastrichtian localities of Laño and Chera to the upper Maastrichtian of Blasi-2, L'Espinau, Serrat del Pelleu and Camí del Soldat (Pereda-Suberbiola et al, 2000;Blain et al, 2010;Company and Szentesi, 2012;this study).…”

“…Besides the locality of Armuña, which has yielded a new anguimorphan with xenosaur affinities and a terrestrial mosasaur (P erez-García et al, this volume), only three localities have provided enough diagnostic material. In the upper Campanian-lower Maastrichtian locality of Laño (Basque-Cantabrian region), the miscellaneous assemblage contained groups of essentially Laurasian distribution (albanerpetontids, alytids and palaeobatrachids) and taxa with close links with the southern continents (madtsoiid snakes) (Astibia et al, 1990;Pereda-Suberbiola et al, 2015). The affinities of lizards were not clear enough to provide palaeobiogeographic information.…”

The most representative vertebrate fossil record and palaeontological heritage from the western Pyrenees

“…Seven genera and ten species have been erected to date in Laño, among which taxa like the snake Herensugea, the turtles Dortoka and Solemys, the crocodiles Musturzabalsuchus and Acynodon (Fig. 2b), the dinosaur Lirainosaurus and the mammal Lainodon (see Pereda-Suberbiola et al, 2015;Pereda-Suberbiola, 2018;and references therein). This assemblage is representative of the late Campanian vertebrate faunas of southern Europe.…”

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

“…Late Cretaceous assemblages confirm that archaic Early Cretaceous lizard faunas were completely replaced by taxa that are much easier to accommodate in modern groups, including possible iguanians, 'scincomorphs', anguids, ?xenosaurs and varanoid anguimorphs, and crown group snakes (Rage, 1999;Blain et al, 2010;Narváez and Ortega, 2010;Pereda-Suberbiola et al, 2015;Blanco et al, 2016;Pérez-García et al, 2016). Even within the Late Cretaceous, there are differences between the composition of first and second halves of this period.…”

“…Because of the paucity of the Iberian Paleocene record, early Eocene assemblages like those described herein provide the best chances for evaluating the recovery of faunas after the K/Pg extinction, but mainly record a migratory event where many taxa from other continents (North America and possibly Asia and/or Africa) joined the poorly diverse Paleocene taxa in Europe. Moreover, the Late Cretaceous Iberian record is also limited, with just a few localities presenting some lizard diversity (Rage, 1999;Blain et al, 2010;Pereda-Suberbiola et al, 2015;Blanco et al, 2016) and always yielding fragmentary material. Such a poor record of lizard assemblages around the K/Pg boundary strongly contrasts with the wellknown assemblages from the Late Jurassic (Seiffert, 1973;Broschinski, 2000) and Early Cretaceous (Evans and Barbadillo, 1997, 1998, 1999Bolet and Evans, 2010b, 2012bEvans and Bolet, 2016), yielding much better preserved specimens and more diverse assemblages.…”