Lo Hueco Research Articles

A Spanish saltasauroid titanosaur reveals Europe as a melting pot of endemic and immigrant sauropods in the Late Cretaceous

A new lithostrotian titanosaur, Qunkasaura pintiquiniestra gen. et sp. nov., is described based on a single partial skeleton from the late Campanian-early Maastrichtian fossil-site of Lo Hueco (Cuenca, Spain). This new taxon is supported by an exclusive combination of characters that highlights strong convergences with members of the South American Aeolosaurini. Qunkasaura allows to reorganise the complex phylogenetic relationships of the increasingly diverse finicretaceous sauropods of Europe. Phylogenetic analyses places Qunkasaura within Saltasauridae and possibly Opisthocoelicaudiinae, together with Abditosaurus. A new clade is established, Lohuecosauria, including Saltasaurus, Lohuecotitan, their most recent common ancestor and all its descendants. Two distinct Ibero-Armorican Campanian-Maastrichtian saltasauroid lineages are recognised: (i) Lirainosaurinae that is exclusive from Europe, and (ii) a saltasaurid lineage with possible opisthocoelicaudiine affinities, with a Laurasian distribution. Lirainosaurinae was a relict lineage including possible dwarf forms that evolved in isolation after reaching Europe before the Late Cretaceous through the Apulian route. The occurrence of opisthocoelicaudiines in Europe may be the result of a Late Cretaceous interchange between Europe and Asia. No evidence of insular dwarfism is found in the Ibero-Armorican opisthocoelicaudiines suggesting that they may have been newcomers to the area that arrived before the ‘Maastrichtian Dinosaur Turnover’ in southwestern Europe.

Femoral diversity in titanosaur sauropods from the Villalba de la Sierra Fm. (Central Spain): Implications for the characterization of faunal turnover in the Ibero-Armorican Late Cretaceous

The late Campanian-Maastrichtian in the Ibero-Armorican domain is rich in titanosaurian fossils. The sauropod remains exhibit a high degree of morphological variability, especially in the commonly-found appendicular elements. The phylogenetic relationships of the Ibero-Armorican titanosaurs are still uncertain but we do know that they experienced a Campanian-Maastrichtian herbivorous faunal turnover. It is probable that the small-to-medium-sized Lirainosaurinae-dominated faunas of the Campanian were replaced by late–early Maastrichtian large-bodied lithostrotian dominated faunas. In this context, the Villalba de La Sierra Formation has yielded an abundant sample of medium-to-large sized titanosaurs. In this study we analyze the morphological variability in the appendicular skeleton of the titanosaurs from the Campanian-Maastrichtian Ibero-Armorican domain. We follow previous attempts to classify the commonly-found isolated titanosaurian femora and expand the proposed methodology. The use of combined phenotypic characters and linear morphometrics can be helpful to analyze the morphological variability and diversity of the Ibero-Armorican titanosaurs. Our findings corroborate the presence of at least two exclusive morphotypes in the Lo Hueco fossil site and one exclusive morphotype in the Poyos site, as well as the presence of previously defined Lirainosaurinae across the Pyrenees during the Campanian-Maastrichtian. The Villalba de La Sierra Formation titanosaurs are also clustered with large-bodied late Maastrichtian titanosaurs. It is possible that either the large-bodied late–early Maastrichtian immigrants, with possible Gondwanan affinities, entered the Iberian Peninsula much earlier or that this group was already present at least during the Campanian-Maastrichtian transition, as the small-sized Lirainosaurinae declined.

New sauropod appendicular remains from the Upper Cretaceous of Romania: Accessing the morphological variability

The Upper Cretaceous sauropod fossil record from Romania is abundant, mostly originated from the Maastrichtian deposits of the western-southwestern margin of the Transylvanian Basin, and in the Hațeg and Rusca Montană basins. Most specimens were found in isolation or in low degree of association and only few partial skeletons have been reported. The presence of at least four taxa was recently considered, including three defined forms: Magyarosaurus dacus, Paludititan nalatzensis and “Magyarosaurus” hungaricus. However, the phylogenetic affinities of these taxa within Lithostrotia are still under debate. A large sample of appendicular remains, predominantly composed by unpublished specimens, is described here in detail to provide new data about the diversity of the sauropods of the Hațeg Island during the Maastrichtian. All specimens show affinities or are compatible with lithostrotian sauropods, even if the availability of characters of some of them does not allow its attribution to this clade. Five morphotypes for the femora, three to four for the humeri, three for the fibulae, and two for the radii, ulnae, manus, pubes, ischia, tibiae, and pedes are established, supporting the presence of four or five taxa in this domain. A unique partial manus morphology characterized by its extreme gracile metacarpals is reported, only surpassed by an unpublished manus found in the Spanish Lo Hueco fossil-site (late Campanian-early Maastrichtian), suggesting that a titanosaurian lineage with extremely elongated manus inhabited the European realm, in both Hațeg and Ibero-Armorican islands, at the end of the Mesozoic.

An Eudromaeosaurian Theropod from Lo Hueco (Upper Cretaceous. Central Spain)

The Lo Hueco fossil site (Cuenca, Spain) is one of the most relevant localities for the study of Late Cretaceous continental vertebrate faunas from Europe. The fossil record of theropod dinosaurs from this locality is represented by scarce isolated postcranial materials that were preliminarily attributed to abelisaurids and to a possible giant bird, in addition to a large assemblage of isolated teeth that were related to different maniraptoran clades. Here, we describe an isolated partial left tibia articulated with the proximal tarsals and discuss their taxonomic affinities. A review of the European fossil record of Late Cretaceous theropods was performed to analyze possible changes in the faunistical composition during this period. The specimen from Lo Hueco exhibits some characters that have been interpreted as apomorphies for maniraptoran coelurosaurs and a combination of features compatible with deinonychosaurians. Within this clade, the specimen is more favorably comparable with velociraptorine dromaeosaurids and is tentatively interpreted as a member of this group. This specimen is one of the few non-dental specimens of dromaeosaurids described thus far from the Upper Cretaceous of the Iberian Peninsula and contributes to a better understanding of the composition and evolutionary history of the European theropod fauna during the last stages of the Mesozoic.

Mark of ectoparasitic activity on a bothremydid (Pleurodira) turtle shell from the Lo Hueco site (Upper Cretaceous, Central Spain)

Shell pitting is relatively abundant but with unclear character and etiology in extinct turtles, since reports on extant turtles with similar condition do not usually include morphological descriptions, illustrations, or data concerning etiology or pathogenesis. Therefore, the available interpretations on shell pitting in the fossil record of turtles are generally speculative or poorly justified. We analyze herein a mark identified in a partial carapace of a bothremydid turtle from the Upper Cretaceous (upper Campanian–lower Maastrichtian) fossil site of Lo Hueco (Cuenca, Central Spain). This mark has been analyzed both through physical examination and by the use of computerized axial tomography scan. The discussion has been established following a differential diagnosis procedure, a presumptive diagnosis was made on the basis of analogy and total or partial similarities with other cases previously documented both in extinct and extant turtle specimens. As a result, information regarding the possible etiology, pathogenesis, and stages of healing of the mark studied here are provided. An ectoparasitic origin is suggested as the most parsimonious hypothesis explaining its etiology, this mark being considered as a pathology. This study represents to the first report of a pathology of ectoparasitic origin in the shell of a bothremydid turtle.

GOING DEEPER INTO MODERN AND FOSSIL CROCODILIAN TOOTH MICROANATOMY: WHAT CAN BE INFERRED OF PALAEOENVIRONMENT AND TAPHONOMY FROM HISTOCHEMICAL ANALYSES?

Teeth provide information about the evolutionary pathway of an organism, its biology and habitat. This is the case even of fossilized teeth, since they have perdurable biomineralized structures, as biological apatite. The material that has been selected for this study comprises teeth from modern crocodilian individuals and extinct Cretaceous crocodylomorphs from Lo Hueco site. Microanatomy, histochemistry and crystallographic nature of enamel, dentine and cementum have been characterized by Polarized Light Microscopy, SEM-EDS, Confocal Raman Spectroscopy and SR-µXRD. A focus has been made on dentine lamination. In the fossil sample short-period incremental lines show alternate presence of dentinal tubules that has not been described previously either in living or fossil archosaur. This could be related to influence of environmental circadian rhythms in the abundance, size and/or activity of cells depositing dentine in the day-night cycle. Regarding histochemical and crystallographic compositions, the major and mostly unique phase is HA, but in the case of fossil teeth, a secondary phase identified as hematite appears locally between discontinuities of the material. Incremental lines would not be related to variation in chemical composition and furthermore do not present different HA crystallographic nature (different directions of HA or different crystallite sizes) either. Only small intensity oscillations are observed in the fossil sample by SR-µXRD which are compatible with the alternating abundance of dentinal tubules. Crystallinity differences between modern and fossil material, as crystallite size and presence of CO32- groups could be explained by postdepositional processes.

3D geometric morphometrics of the hind limb in the titanosaur sauropods from Lo Hueco (Cuenca, Spain)

The Campanian–Maastrichtian Konzentrat-Lagerstätte at Lo Hueco (Spain) has yielded a large sample of appendicular elements referable to sauropod titanosaurs that exhibit considerable morphological variability. The taxonomic assessment of these elements is difficult, they display various degrees of preservation (including fragmentary preservation and taphonomic deformation, each of which were addressed in the methods applied in this study), and also many of the appendicular elements are found as isolated remains. Accurate taxonomic determinations are generally difficult to achieve from the morphological information available on appendicular remains of sauropods, and particularly in groups such as titanosaurirformes. In these cases, the geometric morphometrics (GMM) tool kit is a suitable methodology to explore morphological variability for taxonomic assessment. In this study, several femora, tibiae and fibulae from Lo Hueco were analyzed. To this purpose, the remains were digitized, and the resultant mesh representations were used for definition of 3D landmarks and curves that were analyzed through GMM methods. The quantification of shape variables allowed the use of clustering and K-means techniques as well as a proposed statistical workflow. Several hypotheses of a priori anatomically-defined morphotypes and the results from our machine learning algorithms revealed the presence of two main morphotypes as the most plausible explanation for the morphological variability in the sample of titanosaurian hind limb elements from Lo Hueco.

Synchrotron X-ray microdiffraction to study dental structures in Cretaceous crocodylomorphs

Synchrotron radiation X-ray microdiffraction (SR-μXRD) has been applied for the first time as a fundamental method of analysis to unveil crocodilian teeth growth and development. Teeth from a fossil crocodylomorph from the Upper Cretaceous site of Lo Hueco (Spain) and a modern crocodylian from the living species Crocodylus niloticus have been analysed. Both samples have been studied through Polarized Light Microscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectroscopy, Confocal Raman Spectroscopy, and SR-μXRD. Significant differences have been found in hydroxyapatite (HA) crystallite sizes and texture, and the evolution of these two features along teeth depth. The main differences observed in crystallite size are related to postdepositional processes and/or the environmental and functional pressures of teeth during crocodylomorph life, very different from that of the modern specimen. Regarding the crystalline texture in the tooth enamel, it can be linked to teeth functionality during crocodilian life, causing the directed growth of HA crystallites due to the mechanical stress to which they are subjected.

Three-dimensional analysis of the titanosaurian limb skeleton: implications for systematic analysis

The titanosaurian appendicular skeleton exhibits morphological similarities among different clades and its osteological information is usually less taxonomically meaningful than those of other regions of the skeleton. There is a probable morphological convergence due to morphofunctional similarities between members of different titanosaurian groups. In addition, higher intraspecific variability has hindered the assessment of similar forms such as the Late Cretaceous titanosaurians of the Ibero-Armorican domain. The use of 3D-geometric morphometrics and discriminant analyses on an abundant sample of titanosaurian limb elements from the Lo Hueco site and other titanosaurian taxa has been able to characterize the differences between several sauropod clades with the control of the intraspecific variability. Similar methods with the use of surface analyses of other titanosaurs enabled the recognition of morphological similarities congruent with morphofunctional convergences between one of the lithostrotian morphotypes identified in Lo Hueco (the Morphotype II) and some gracile colossosaurs such as Mendozasaurus neguyelap. In contrast, Morphotype I at Lo Hueco present a more typical titanosaurian morphology, resembling Jainosaurus cf. septentrionalis. The use of discriminant analyses allowed us to distinguish Colossosauria on the basis of limb morphology for the first time. We also observed that Colossosauria and Saltasauridae diverge from a more typical titanosaurian non-autopodial limb skeleton. Our results also suggest a highly different and specialized limb skeleton for the Saltasauridae in comparison with other sampled titanosaurians. The use of surface semilandmarks and discriminant analyses also allowed us to propose several new potential osteological characters for use in phylogenetic analyses through the maximization of differences between the sampled clades.

Controlled chemical cleaning in paleontological preparation: the use of gels on vertebrate fossil remains from the Late Cretaceous of Spain

espanolLa conservacion del patrimonio paleontologico depende en gran medida de la diversidad y complejidad de los materiales que componen tanto los fosiles como la matriz que los incluye y los llena. Una practica comun en los tratamientos de preparacion fosil consiste en eliminar parte de la matriz circundante que, en algunos casos, impide el acceso directo a las muestras o pone en riesgo su conservacion. Por estas razones, es necesario el uso de tratamientos confables que no comprometan la estabilidad fosil durante el proceso de eliminacion de la matriz. Los metodos de limpieza basados en el uso de soluciones gelifcadas pueden ser un remedio para algunos de esos tratamientos en los que el uso de tecnicas tradicionales pone en peligro la preservacion de los fosiles. Aqui se discute la efcacia de diferentes tecnicas de limpieza quimica con soluciones gelifcadas que utilizan diferentes agentes espesantes, acidos, quelantes y tensioactivos que se pueden aplicar a los fosiles del yacimiento paleontologico de Lo Hueco (Cuenca, Espana). EnglishThe conservation of paleontological heritage depends greatly on the diversity and complexity of the materials that compose both the fossils and the matrix that includes and flls them. A common practice in fossil preparation treatments consists in removing part of the surrounding matrix that, in some cases, prevents direct access to the specimens or puts its conservation at risk. For this reasons, it is necessary the use of reliable treatments that do not compromise the fossil stability during the process. Cleaning methods based on the use of gelifed solutions can be a remedy for some of those treatments in which the use of traditional techniques put in danger the preservation of the fossils. Here it is discussed the efcacy of diferent chemi‑ cal cleaning techniques with gelled solutions using diferent thickening agents, acids, chelants and surfactants that can be applied to the fossils from Lo Hueco fossil site (Cuenca, Spain).

Updating titanosaurian diversity (Sauropoda) from the Late Cretaceous of Spain: the fossil sites of Laño and Chera

Three titanosaurian sauropods are well-known from the Campanian-Maastrichtian of the Ibero-Armorican Island (southwestern Europe): Lirainosaurus astibiae from Spain, and Ampelosaurus atacis and Atsinganosaurus velauciensis from France. However, a higher titanosaurian diversity has been suggested for this island, a hypothesis that has gained traction in recent years as a result of new discoveries in fossil sites from Spain and southern France. An estimation of the titanosaurian diversity in the late Campanian-early Maastrichtian of the Iberian Peninsula is made here on the basis of the available information from the three fossil sites that have yielded the best preserved fossil remains: Laño (Condado de Treviño), Chera (Valencia), and Lo Hueco (Cuenca). The results confirm the hypothesis of a higher titanosaurian diversity in the Iberian Peninsula: from one to, at least, three taxa. Moreover, we also suggest the presence of two different titanosaurian morphotypes in the site of Chera, with one of them representing Lirainosaurus

Neuroanatomical and neurosensorial analysis of the Late Cretaceous basal eusuchian Agaresuchus fontisensis (Cuenca, Spain)

AbstractAgaresuchus fontisensis is an allodaposuchid crocodile from the Campanian–Maastrichtian (Late Cretaceous) of Lo Hueco (Cuenca, Spain). Allodaposuchidae is a clade of European basal eusuchians, which is considered a part of the stem group of Crocodylia. The holotype and paratype skulls of Agaresuchus fontisensis were scanned on computed tomography and their internal cavities, including those of the brain, nerves and blood vessels, as well as the paratympanic sinus system and the paranasal sinuses, digitally reconstructed. The cranial endocast and pneumatic sinuses were then compared with those of other crocodyliforms. The neuroanatomy of Agaresuchus fontisensis resembles those of other mesoeucrocodylians, sharing some morphological traits with extant crocodiles. The neurosensorial and cognitive capabilities inferred from the inner skull cavity reconstructions of Agaresuchus fontisensis are similar to those of other eusuchians. The olfactory acuity of Agaresuchus fontisensis is low by crocodylian standards, closer to that of the alligatoroids rather than to that of the crocodyloids. Its visual acuity is similar to that of Lohuecosuchus megadontos, a sympatric allodaposuchid also found in the fossil site of Lo Hueco.

First palaeoneurological study of a sauropod dinosaur from France and its phylogenetic significance

Despite continuous improvements, our knowledge of the palaeoneurology of sauropod dinosaurs is still deficient. This holds true even for Titanosauria, which is a particularly speciose clade of sauropods with representatives known from numerous Cretaceous sites in many countries on all continents. The data currently available regarding the palaeoneurology of titanosaurs is strongly biased towards Gondwanan forms (Argentina above all, but also India, Malawi and Australia). In contrast, the palaeoneurology of Laurasian titanosaurs is known only from a few taxa from Spain and Uzbekistan, despite the discovery in other countries of Laurasia of a number of neurocranial remains that would lend themselves well to investigations of this kind. To fill in this gap in our knowledge, we subjected a titanosaurian braincase from the uppermost Upper Cretaceous of southern France to X-ray computed tomographic scanning, allowing the generation of 3D renderings of the endocranial cavity enclosing the brain, cranial nerves and blood vessels, as well as the labyrinth of the inner ear. These reconstructions are used to clarify the phylogenetic position of the specimen from the Fox-Amphoux-Métisson site. A combination of characters, including the presence of two hypoglossal rami on the endocast, the average degree of development of the dorsal-head/caudal-middle-cerebral vein system and the relatively short and subequal lengths of the ipsilateral semicircular canals of the labyrinth, are particularly revealing in this respect. They suggest that, compared with the few other Laurasian titanosaurs for which in-depth palaeoneurological data are available, the French taxon is more derived than the distinctly more ancient, possibly non-lithostrotian titanosaur from the Uzbek site of Dzharakuduk but more basal than derived saltasaurids, such as the coeval or slightly more recent forms from the Spanish locality of Lo Hueco.

Inner skull cavities of the basal eusuchian Lohuecosuchus megadontos (Upper Cretaceous, Spain) and neurosensorial implications

The Late Cretaceous fossil site of Lo Hueco (Cuenca, Spain) has yielded a large collection of tetrapod remains, in which crocodyliforms are one of the best represented groups. The crocodyliforms from Lo Hueco helped establish Allodaposuchidae as one of the sister-groups of Crocodylia. A complete skull of the holotype of the allodaposuchid Lohuecosuchus megadontos was CT scanned, and all its inner cavities, including those of the brain, nerves, inner ear and blood vessels, as well as the paratympanic sinus system and the paranasal sinuses, were three-dimensionally reconstructed and compared to those of several extant and extinct crocodylians. The endocranial anatomy of Lohuecosuchus megadontos is congruent with its phylogenetic position as a basal eusuchian. Our work suggests that some of the neurosensorial capabilities found in the crown-group Crocodylia such as an acute sense of olfaction and a low frequencies hearing are already present at the base of Eusuchia.

Identification of the French Upper Cretaceous bothremydid turtle Foxemys mechinorum in the Spanish record

Bothremydidae is the most abundant and diverse group of turtles in the upper Cretaceous fossil sites of southwestern Europe. Several species a priori recognized as exclusive of the Portuguese, Spanish and French records were defined. The most abundant and best-preserved Spanish collection of pleurodiran turtles from the last Stages of the Upper Cretaceous comes from the fossil site of Lo Hueco (Cuenca Province, Central Spain). The bothremydid Iberoccitanemys convenarum, defined by a single specimen from the Maastrichtian of Haute-Garonne (Southern France), was subsequently recognized as a very abundant form in this Spanish site, corresponding to the only bothremydid so far identified as being part of the diversity of Bothremydidae of both countries. The presence of a second member of Bothremydidae was recognized in Lo Hueco, representing the only evidence of the synchronic and sympatric coexistence of two members of this lineage in a European site. However, very scarce information about this second form from Lo Hueco was available. Thus, its attribution to a new taxon or to a member of Foxemydina previously identified in the Spanish record, or in that of other European regions, could not be evaluated until now. New material from Lo Hueco, not attributable to I. convenarum but to this second larger form, allows its generic and specific identification. Close paleobiogeographical relationships considering the fauna of pleurodiran turtles from Spain and France are recognized thanks to the findings performed in Lo Hueco: not only I. convenarum is known in both countries, but also the French Foxemys mechinorum is identified in Central Spain.

Pelvic and femoral anatomy of the Allodaposuchidae (Crocodyliformes, Eusuchia) from the Late Cretaceous of Lo Hueco (Cuenca, Spain)

The fossil record of postcranial remains assigned to Allodaposuchidae is currently sparse. However, the Late Cretaceous paleontological site of Lo Hueco (Cuenca, Spain), from where two new taxa of allodaposuchid have been described, has yielded numerous postcranial remains assignable to this clade. Among them, the large amount of pelvic and femoral material is notable, providing the opportunity to study these allodaposuchid elements and assess their morphological similarity with other eusuchian remains. The comparison with extant crocodylians was accomplished using traditional morphometric techniques, whereas the comparison with other fossils and establishment of morphotypes was done using morphological criteria. The results of the cluster and principal components analyses show morphological differences between extant crocodylians and allodaposuchids from Lo Hueco, allowing the segregation of these lineages. The similarities found between the pelvic and femoral remains from Lo Hueco, and those referred to Allodaposuchus precedens and other putative allodaposuchids from the Iberian Peninsula, allows referral of these remains to allodaposuchids. The differences found among the femoral and pelvic remains of Lo Hueco enables us to recognize two morphotypes per each element. This study allows a better understanding of allodaposuchid postcranial elements that were previously poorly known. The ilia, ischia and femora from Lo Hueco allodaposuchids are distinct from those of other crocodylian lineages. Finally, the fact that there are two morphotypes per each element at Lo Hueco is congruent with the presence of two different allodaposuchids at the site.

The internal anatomy of titanosaur osteoderms from the Upper Cretaceous of Spain is compatible with a role in oogenesis

Dermal armor is one of the most intriguing features of some titanosaurs, the only sauropod dinosaurs that bore osteoderms. Some studies have revealed cavities of varying sizes inside some titanosaur osteoderms, interpreted as the result of bone remodeling for mineral mobilization. Several hypotheses have been proposed to explain the need for mineral mobilization in titanosaurs. However, rejecting those hypotheses was difficult with hitherto available evidence. The Upper Cretaceous site of Lo Hueco (Cuenca; Spain) has yielded one of the largest titanosaur osteoderm sets available. Observation of pre-existing breakages in the fossils and CT-scanning have revealed a predominant internal channel network for bulb and root osteoderms: most had a very compact spongy bone core, perfused by large longitudinal branching neurovascular canals. Only few osteoderms from the same bed, which was deposited in a single and short event, had areas with low-density spongy bone. This void-like low-density bone is always associated with internal channels. It is also present in osteoderms of different sizes. This scenario is best explained when considering that Lo Hueco titanosaurs might have used their osteoderms as a source of calcium that was mobilized during oogenesis, although other hypotheses cannot be completely ruled out.

A new titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Lo Hueco (Cuenca, Spain)

The upper Campanian-lower Maastrichtian site of Lo Hueco (Cuenca, Spain) has provided a set of well-preserved partial skeletons in anatomical connection or with a low dispersion of their skeletal elements. One partial skeleton is herein described and a new titanosaurian sauropod is established, Lohuecotitan pandafilandi. This titanosaur is diagnosed by eight autapomorphic features: dorsally and ventrally widened or bifurcated posterior centrodiapophyseal lamina in anterior and middle dorsal vertebrae; short postspinal lamina with a transversely expanded distal end represented by smooth scars in the dorsal vertebrae; anteriormost caudals with the medial spinoprezygapophyseal and medial spinopostzygapophyseal laminae ventrally connected with the prespinal and postspinal laminae, respectively; anterior caudal neural spines with a dorsal projection of the prespinal and postspinal laminae; anterior caudal neural spines bears a “greek-cross”-like cross-section; middle caudal centra having two round and rough structures in the dorsal edge of the posterior articulation, which extends to the dorsal surface of the centrum; the articular ends of the rami of the haemal arches are divided in two articular surfaces; and tuberosity between the anterior and the lateral trochanter of the fibula. The herein performed phylogenetic analysis considered L. pandafilandi as a member of Lithostrotia more derived than Malawisaurus. The known palaeodiversity of the Late Cretaceous Ibero-Armorican titanosaurs is increasing, and further analyses focused on this group will be necessary to better understand the evolutionary history of European titanosaurs and to clarify their relationships within Titanosauria.

New Spanish Late Cretaceous eusuchian reveals the synchronic and sympatric presence of two allodaposuchids

The recently described clade Allodaposuchidae includes European eusuchian crocodyliforms restricted to the Late Cretaceous (Campanian and Maastrichtian). A new allodaposuchid crocodyliform is here described based on two specimens from the upper Campanian–lower Maastrichtian fossil site of Lo Hueco (Cuenca, Spain). This new taxon, Agaresuchus fontisensis gen. et sp. nov., is described by two complete skulls and a lower jaw associated with one of them. This new species can be distinguished unambiguously from Lohuecosuchus megadontos, the other allodaposuchid known from the same fossil site. The presence of two allodaposuchid crocodyliforms in Lo Hueco allows the recognition of the synchronic and sympatric existence of two representatives of this clade for the first time. The new genus Agaresuchus, comprises a previously described Iberian allodaposuchid species, “Allodaposuchus” subjuniperus, as Agaresuchus subjuniperus, new combination.

New Crocodyliforms from Southwestern Europe and Definition of a Diverse Clade of European Late Cretaceous Basal Eusuchians.

The late Campanian-early Maastrichtian site of Lo Hueco (Cuenca, Spain) has provided a set of well-preserved crocodyliform skull and lower jaw remains, which are described here and assigned to a new basal eusuchian taxon, Lohuecosuchus megadontos gen. et sp. nov. The reevaluation of a complete skull from the synchronous site of Fox-Amphoux (Department of Var, France) allows us to define a second species of this new genus. Phylogenetic analysis places Lohuecosuchus in a clade exclusively composed by European Late Cretaceous taxa. This new clade, defined here as Allodaposuchidae, is recognized as the sister group of Hylaeochampsidae, also comprised of European Cretaceous forms. Allodaposuchidae and Hylaeochampsidae are grouped in a clade identified as the sister group of Crocodylia, the only crocodyliform lineage that reaches our days. Allodaposuchidae shows a vicariant distribution pattern in the European Late Cretaceous archipelago, with several Ibero-Armorican forms more closely related to each other than with to Romanian Allodaposuchus precedens.