Miguel Moreno-Azanza

La Cantalera: an exceptional window onto the vertebrate biodiversity of the Hauterivian-Barremian transition in the Iberian Peninsula

La Cantalera is an accumulation site for fossil vertebrates consisting mainly of teeth and isolated postcranial remains. It has the greatest vertebrate biodiversity of any site from the Hauterivian-Barremian transition in the Iberian Peninsula. Up to now, 31 vertebrate taxa have been recognized: an osteichthyan (Teleostei indet.), two amphibians (Albanerpetonidae indet. and Discoglossidae indet.), a chelonian (Pleurosternidae? indet.), a lizard (Paramacellodidae? indet.), four crocodylomorphs (cf. Theriosuchus sp., Bernissartiidae indet., Goniopholididae indet., cf. Lisboasaurus sp.), two pterosaurs (Istiodactylidae? indet., Ornithocheiridae? indet.), four ornithopod dinosaurs (Iguanodontoidea indet., Hadrosauroidea? indet., “Hypsilophodontidae” indet., Rhabdodontidae? indet.), a thyreophoran (Polacanthidae indet.), a sauropod (Euhelopodidae indet.), eleven theropods (Carcharodontosauridae? indet., Baryonychinae indet., aff. Paronychodon sp., Maniraptora indet. 1-3, Dromaeosaurinae indet. 1-3, Velociraptorinae indet., Avialae? indet.) and three or four multituberculate mammals (Cantalera abadi, Eobaatar sp., Plagiaulacidae or Eobaataridae gen. et sp. indet., “Plagiaulacida” indet.). Nine ootaxa have also been distinguished at the site of La Cantalera. Oofamilies assigned to dinosaurs (Elongaloolithidae, Prismatoolithidae, cf. Spheroolithidae), to crocodiles (Krokolithidae) and eggshells of two oofamilies incertidae sedis are represented. This association is consistent with the record of bone and tooth remains from the site. La Cantalera was formed in a marshy environment where there was an intermittent body of water. The great majority of the vertebrate fossil remains lack evidence of transport, so the preserved association is a good representation of the vertebrate ecosystem in or around the marshy area of La Cantalera. The vertebrate association of La Cantalera displays certain differences with respect to those from lacustrine environments of the Hauterivian-Barremian transition of the Iberian Range. These differences include, for example, the absence of Chondrichthyes, the merely token presence of the osteichthyans, the scarcity of chelonians, the presence of exclusively multituberculate mammals, the lower diversity of sauropods and the greater diversity of theropods.

The eusuchian crocodylomorph Allodaposuchus subjuniperus sp. nov., a new species from the latest Cretaceous (upper Maastrichtian) of Spain

This paper describes the skull of the eusuchian Allodaposuchus subjuniperus sp. nov. This new skull was recovered between the villages of Beranuy and Serraduy del Pon (Huesca, Spain). Stratigraphically, it was located in a level of coarse-grained sandstones in the middle-upper part of the lower red unit (Conqués Formation) of the Tremp Group, in the uppermost Maastrichtian close to the Cretaceous–Paleogene boundary. Until now Allodaposuchus was a monospecific genus. Phylogenetic analysis places the new taxon as a basal member of Eusuchia forming a clade with the other European Allodaposuchus remains and as a sister clade to the endemic European members of Hylaeochampsidae. Furthermore, Allodaposuchus and Hylaeochampsidae are within the stem of Crocodylia, being key taxa to understanding the origin of Crocodylia. The new taxon is the latest record of Allodaposuchus from Europe, and it presents significant enough morphological differences from Allodaposuchus precedens to establish a new species. The morphological variations in the material included in Allodaposuchus, the wide range of age and the geographical separation among the remains from Romania, France and Spain indicate that Allodaposuchus is not a monospecific genus as traditionally established.http://zoobank.org/96CCE2FE-531A-4479-BE54-172D589D16A0

New information about the stratigraphic position and age of the sauropod Aragosaurus ischiaticus from the Early Cretaceous of the Iberian Peninsula

The sauropod Aragosaurus ischiaticus Sanz, Buscalioni, Casanovas & Santafe, 1987 was the first dinosaur to be described in Spain. The holotype was recovered from the site of Las Zabacheras (Galve, Teruel province). This site has traditionally been situated in the El Castellar Formation (in the lower part of the Wealden facies). Recently, it has been proposed that the remains of Aragosaurus stem from the Villar del Arzobispo Formation (late Tithonian–upper part of the early Berriasian), which would mean that the sauropod was almost 15 million years older than previously thought. Detailed field work has been carried out, making it possible to pinpoint the position of the low-angle unconformity between the Villar del Arzobispo Formation and the El Castellar Formation. This unconformity originated as a result of block tilting that occurred during the early stages of the Early Cretaceous rifting episode. The upper levels of the Jurassic sequence (i.e. the Villar del Arzobispo Formation) were exposed to erosion and karstification, leading to the formation of a discontinuous conglomeratic level. This level has been locally preserved at the bottom of the Wealden syn-rift sequence (i.e. the El Castellar Formation). The results of our detailed mapping demonstrate that the Aragosaurus holotype was found in the lower part of the El Castellar Formation. Moreover, our revision of the existing datings suggests that the El Castellar Formation as a whole is Valanginian?–early Barremian in age. Given that Aragosaurus was located in its lower part, it is probably Valanginian?–Hauterivian in age.

The first metriorhynchid crocodylomorph from the Middle Jurassic of Spain, with implications for evolution of the subclade Rhacheosaurini.

Background Marine deposits from the Callovian of Europe have yielded numerous species of metriorhynchid crocodylomorphs. While common in English and French Formations, metriorhynchids are poorly known from the Iberian Peninsula. Twenty years ago an incomplete, but beautifully preserved, skull was discovered from the Middle Callovian of Spain. It is currently the oldest and best preserved metriorhynchid specimen from the Iberian Peninsula. Until now it has never been properly described and its taxonomic affinities remained obscure. Methodology/Principal Findings Here we present a comprehensive description for this specimen and in doing so we refer it to a new genus and species: Maledictosuchus riclaensis. This species is diagnosed by numerous autapomorphies, including: heterodont dentition; tightly interlocking occlusion; lachrymal anterior process excludes the jugal from the preorbital fenestra; orbits longer than supratemporal fenestrae; palatine has two non-midline and one midline anterior processes. Our phylogenetic analysis finds Maledictosuchus riclaensis to be the basal-most known member of Rhacheosaurini (the subclade of increasingly mesopelagic piscivores that includes Cricosaurus and Rhacheosaurus). Conclusions/Significance Our description of Maledictosuchus riclaensis shows that the craniodental morphologies that underpinned the success of Rhacheosaurini in the Late Jurassic and Early Cretaceous, as a result of increasing marine specialization to adaptations for feeding on fast small-bodied prey (i.e. divided and retracted external nares; reorientation of the lateral processes of the frontal; elongate, tubular rostrum; procumbent and non-carinated dentition; high overall tooth count; and dorsolaterally inclined paroccipital processes), first appeared during the Middle Jurassic. Rhacheosaurins were curiously rare in the Middle Jurassic, as only one specimen of Maledictosuchus riclaensis is known (with no representatives discovered from the well-sampled Oxford Clay Formation of England). As such, the feeding/marine adaptations of Rhacheosaurini did not confer an immediate selective advantage upon the group, and it took until the Late Jurassic for this subclade to dominate in Western Europe.

A re-evaluation of aff. Megaloolithidae eggshell fragments from the uppermost Cretaceous of the Pyrenees and implications for crocodylomorph eggshell structure

The Upper Cretaceous outcrops of the Pyrenees yield one of the most extensive and continuous records of paleoological remains anywhere in the world. Most of eggs and eggshells have been referred to the oofamily Megaloolithidae. In this study, we present a revision of eggshell fragments from the Blasi 2 locality, lattermost Maastrichtian in age, previously assigned to aff. Megaloolithidae. The presence of a blocky extinction pattern and basal knobs supports a crocodilian affinity of these materials. We classify them as Krokolithidae indet. Three structural layers can be recognised in the Blasi 2 eggshells, a feature that is shared with other recent eggshells (e.g. Crocodylus porosus and Crocodylus niloticus) and fossil crocodylomorph eggshells (Krokolitheswilsoni), which were previously described as single layered. The new proposed affinity of the Blasi 2 eggshells reduces the Megaloolithidae oodiversity of the last few million years of the Cretaceous in the Pyrenees to only two valid ootaxa, Megaloolithusmamillare and Megaloolithusbaghensis. The lack of more complete material precludes the erection of new ootaxa based on the Blasi 2 material.

Unusual Theropod Eggshells from the Early Cretaceous Blesa Formation of the Iberian Range, Spain

Trigonoolithus amoae oogen. et oosp. nov. is described on the basis of abundant eggshell fragments from the La Cantalera 1 site in the Early Cretaceous (early Barremian) Blesa Formation, Teruel Province, northern Spain. The surface ornamentation, the most diagnostic feature of the new oogenus, consists of closely spaced sub-triangular or rounded protuberances that have not previously been reported in any other ootaxon. The eggshells present three distinct layers, with a gradual transition between prismatic and mammillary layers, and a poorly developed external layer with progressive prismatic to external layer transition, a combination of characters that allows them to be assigned to Prismatoolithidae. Phylogenetic analyses based on oological characters place Trigonoolithus at the base of Prismatoolithidae.

Growth mechanisms in dinosaur eggshells: an insight from electron backscatter diffraction

ABSTRACT The direct relationship between eggshell structure and eggshell formation is well established for avian eggs, but has never been studied in depth in non-avian dinosaurs. Both biological and crystallographic mechanisms take part in eggshell formation, due to its dual mineralogical and proteinaceous nature, but the exact relative contributions of these processes are still poorly known. Competitive growth has been postulated to be the general mechanism leading to the characteristic columnar construction seen in dinosaur eggshell. Here we analyze the eggshell structure of both ornithopod and non-avian theropod ootaxa with orientation contrast imaging and electron backscatter diffraction and present the first misorientation angle boundary maps of fossil eggshell, in order to ascertain whether competitive growth can explain the development of the columnar structure in non-avian dinosaur eggshell. Our results show that both eggshell types can be constructed via competitive growth, and that small changes in organic core spacing and crystal grain size, which are organically controlled, may develop into major changes in general eggshell structure, which will determine the physical properties of the egg. However, interseed distance cannot be directly correlated with organic core spacing as the competitive growth model predicted.

New Material and Phylogenetic Position of Arenysaurus ardevoli, a Lambeosaurine Dinosaur from the Late Maastrichtian of Arén (Northern Spain)

ABSTRACT Arenysaurus ardevoli is a lambeosaurine hadrosaurid from the late Maastrichtian of Arén (Huesca, northern Spain) that has recently been described. The holotype is the first and the most complete lambeosaurine with a braincase from Europe. In this paper, we present a complete description of the postcranial skeleton, which was poorly described when the taxon was named because it was partially unprepared, and new information on several cranial bones (jugal, maxilla, and dentition). A new phylogenetic analysis of Arenysaurus and the closely related Blasisaurus canudoi, also from the late Maastrichtian of Arén, places them inside the Parasaurolophini in a dichotomy with Parasaurolophus spp. Paleobiogeographically, the presence of Arenysaurus and its relationships with other lambeosaurines suggest at least one geodispersal event from Asia to Europe no later than the middle—late Campanian.

New dryolestidan mammal from the Hauterivian-Barremian transition of the Iberian Peninsula

Cuenca-Bescós, G., Badiola, A., Canudo, J.I., Gasca, J.M., and Moreno-Azanza, M. 2011. New dryolestidan mammal from the Hauterivian—Barremian transition of the Iberian Peninsula. Acta Palaeontologica Polonica 56 (2): 257–267. Crusafontia amoae sp. nov. (Dryolestida, Stem Cladotheria) is represented by two isolated upper molars (M4 or M5 and M6 or M7) from the terminal Hauterivian—basal Barremian (Early Cretaceous) of the El Castellar Formation (Galve, Spain). The molars have a deep ectoflexus, a distinct metacone, a continuous metacrista, and an antero-lingually placed paracone. They differ from the molars of the other species of the genus, Crusafontia cuencana, by their larger size, by their outsized parastyle, by the pointed lingual slope of the paracone, their more symmetrical appearance with a deep ectoflexus in occlusal view, and the well-developed metacone. Revision of three isolated teeth previously attributed to Crusafontia cuencana suggests that instead of being upper premolars belonging to Crusafontia cuencana they in fact belong to Pocamus pepelui, of the stem cladotherian superorder Zatheria, probably “peramuran”. As such, the stem Cladotheria record from the Early Cretaceous of the Iberian Peninsula is composed of two dryolestids (Crusafontia amoae and Crusafontia cuencana) and one zatherian (Pocamus pepelui). Key words: Mammalia, Cladotheria, Dryolestida, Crusafontia, systematics, Cretaceous, Iberian Peninsula.

Spalacotheriid ‘Symmetrodonts’ from the Early Cretaceous of Spain

ABSTRACT Spalacotheriids, basal trechnotheres with an acutely angled, reversed-triangle pattern of major molar cusps, are relatively rare pan-Laurasian mammals that ranged through much of the Cretaceous but are generally not well represented in the fossil record. Herein we describe newly collected specimens from the Molino Alto 1 locality, Teruel Province, Spain, and review previously described materials from the nearby locality of Galve; the sites lie in the same horizon in the upper El Castellar Formation and are of early Barremian age. On this basis, we recognize and name Aliaga molinensis, gen. et sp. nov., and provisionally place in the same genus a previously described species, cf. Aliaga henkeli, comb. nov., which appears to be the largest known spalacotheriid. The two species are characterized by a distinctive, multicuspate cingulid on lower cheek teeth. Based on acuteness of molar cusp triangulation and other features (e.g., planar molar shearing surfaces, elongation and cusp pattern of penultimate premolar, reduction of last molar, simplification of upper molar crown pattern), the species are referred to the Spalacolestinae. This subfamily is most diverse in North America, where it ranged from Albian—Campanian, but first appears in the Barremian of Western Europe, supporting the hypothesis that the group had a Eurasian origin and later dispersed to North America.