Search Results (27)

New ornithopod remains have recently been discovered at the Vadillos-1 paleontological site, in Cuenca Province, Central Spain. These remains were collected in sandy and clayey deposits within “Wealden” alluvial facies, which correspond to an upper Barremian (Lower Cretaceous) alluvial-palustrine muddy floodplain paleoenvironment. The remains correspond to a part of a sacrum, including three fused sacral vertebral centra with sacral ribs and part of the sacral yoke, together with an isolated unfused sacral vertebra. An incomplete ischium has also been identified, likely belonging to the same individual. The sacral block exhibits a broad sulcus that begins at the most anterior sacral vertebra, continues through the middle vertebra, and ends in the area where the middle and the most posterior vertebrae are fused. The non fused sacral vertebra also displays a ventral sulcus. The incomplete ischium has a curved shaft with a triangular cross section towards the distal end. The combination of the morphological features of the sacrum and ischium allow its attribution to Iguanodon cf. bernissartensis. This species is identified in the area for the first time, adding new valuable data about the dinosaur assemblages from the Lower Cretaceous of Spain. Full article

Giant Paleogene groundbirds named Gastornis have long been known from Europe, with similar fossils from North America being placed in the genus Diatryma. A more recent discovery in China is evidence that these birds had wide geographic distribution. The name Gastornis is now generally considered to be the name that has historical precedence. Historically, Gastornis has been interpreted as being a fierce predator, but anatomical and isotopic evidence suggests that the giant birds were herbivores. Gastornithid tracks preserved in Lower Eocene fluvial sediments of the Chuckanut Formation in northwest Washington State, USA, support the herbivore interpretation. These tridactyl footprints preserve broad triangular toenails rather than talons. The Chuckanut Formation gastornithid tracks have been given the ichnotaxonomic name Rivavipes giganteus Mustoe et al. (2012). In 2024, two important new discoveries were made. These are a trackway that preserves three adult tracks, and two tracks left by a gastornithid chick.The adult bird trackway has stride and pace distances that are consistent with the short lower limb bones (tarsometatarsals) observed in Gastornis skeletal remains. The reproductive strategies of gastornithids remain enigmatic; the evidence consists of numerous egg shell fragments found at sites in France and the newly discovered Chuckanut tracks. Full article

We describe the first fossil traces from the skeletal remains of dinosaurs from Uruguay, from the Upper Cretaceous Guichón Formation. We describe the first biting/gnawing fossil traces reported for Uruguay, Machichnus bohemicus Mikulás et al., 2006, probably made by small tetrapods, such as multituberculate mammals. Moreover, traces likely made by sarcosaprophagous beetles, namely Cubiculum Roberts et al., 2007, cf. Cubiculum, and cf. Osteocallis Roberts et al., 2007, are described. The presence of Cubiculum and Osteocallis supports previously proposed depositional conditions in a warm and arid to semi-arid continental environment for the referred stratigraphical unit. All traces would indicate a certain period of subaerial exposure before the definitive burial of the bones. Full article

Mesosaurs have long been considered to be small to mid-sized aquatic to semiaquatic amniotes that lived in Gondwana during the Early Permian or Late Carboniferous, according to recent research that showed their ghost range extending back to the Pennsylvanian. Previous morphometric analyses based on several hundred mesosaur specimens, including materials from Uruguay, Brazil, South Africa, Namibia, and the Paris National History Museum, provided a comprehensive understanding of mesosaur ontogeny, documented from fetus to adults. As a result, it was possible to determine the approximate size of any individual, measuring just one isolated limb bone, vertebrae, or even cranial elements. Herein, we describe large, poorly preserved and incomplete skulls, as well as axial and appendicular bones, from the Mangrullo Formation Konservat-Lagerstätte of Uruguay that suggest the existence of gigantism in mature mesosaurs reaching more than twice the size of previously described adults and type specimens. The sporadic occurrence of these giant individuals contrasts sharply with the abundant remains of young mesosaurs and, in general, with what is commonly found in the fossil record of vertebrates. The poor preservation of the mature individuals and their presence in coastal areas of the basin is consistent with the hypothesis that older mesosaurs have spent more time near the coast. An alternative hypothesis suggesting pelagic lifestyles is less supported by the available data. Given the preservation of unborn and hatchlings, as well as early juvenile, mature and very mature individuals, the mesosaur record is considered exceptional among early amniotes. Full article

A newly discovered deposit on the bed of the Steinhatchee River produced a moderately diverse assemblage of 15 vertebrate taxa herein designated the Steinhatchee River 2A (STR 2A) local fauna. Mammalian taxa isotopically shown from other sites to be either grazers or grazing-dominated mixed-feeders numerically dominate the fauna, especially a species of Equus. About 75% of the 552 identifiable fossils from STR 2A, representing a minimum of nine individuals, are referred to the informally named Equus (Equus) sp. A. The site produced the first known examples of associated upper and lower cheekteeth and lower incisors for this species, and also one of just two records outside of central and southern peninsular Florida. Like most Pleistocene sites in Florida, xenarthrans are diverse, with two cingulates, Dasypus and Holmesina, and two pilosans, Paramylodon and Megalonyx. An astragalus and several metatarsals of Holmesina are within the size range of H. septentrionalis, but also have some characteristics found in the older species H. floridanus. These finds corroborate that an evolutionary transition between these two species occurred in Florida during the Irvingtonian. The age of STR 2A is most likely middle Irvingtonian, ca. 0.5–0.7 Ma, an interval poorly known in Florida and the rest of the southeastern USA. Full article

The poor preservation state of chitinozoans recovered from samples of the La Pola (Sandbian–Katian) and Don Braulio formations (Hirnantian-Llandovery), after being processed with standard methods, required significant modifications in processing. The sodium hexametaphosphate technique was used to avoid invasive mechanical procedures. Hence, more complete chitinozoans that preserved original features produced by biological, mechanical, and chemical degradation appeared. The processes that affected the good preservation of the chitinozoan exine are associated with factors inherent to the sedimentary environment, and biological and geological taphonomic effects that occurred in different regions of the Precordillera, added to the important associated tectonic activity. The thermal alteration was also an important factor in the fragile and brittle condition of the organic matter recovered. This transcends the preservation-processing technique relationship to be used. The results obtained from non-standard processing contribute to the paleoenvironmental interpretation of the Pola and Don Braulio successions, which are still widely discussed, and the determination of the most accurate age of the La Pola Formation. The latter will allow us to propose a biostratigraphic correlation between chitinozoan zones and graptolite zones, given the presence of both groups in the succession studied here, and to establish correlations with other successions in the Precordillera and elsewhere. Full article

The end of the Cretaceous saw the Western Interior Seaway divide North America into two land masses, Laramidia in the west and Appalachia in the east. Laramidian dinosaurs inhabited a narrow strip of land extending from Mexico to Alaska. Within this geographically restricted area, dinosaurs evolved high diversity and endemism, with distinct species in the north and south. Here, we report a new tyrannosaurid from the Late Campanian-aged Cerro del Pueblo Formation of Coahuila, Mexico, which is part of a tribe of tyrannosaurs originating in southern Laramidia. Phylogenetic analysis recovers the new tyrannosaur as part of a clade including Labocania anomala from the La Bocana Roja Formation of Baja California Norte, Bistahieversor sealeyi from the Kirtland Formation of New Mexico, Teratophoneus curriei from the Kaiparowits Formation in Utah, and Dynamoterror dynastes from the Menefee Formation of New Mexico. Distinct frontal morphology and the younger age (~72.5–73 Ma versus >75.8 Ma for L. anomala) support recognition of the new tyrannosaur as a distinct species of Labocania, Labocania aguillonae. The Labocania clade dominated southern Laramidia at a time when the north was dominated by daspletosaurins and albertosaurines. The high endemism seen in tyrannosaurids is remarkable, given that modern apex predators have large geographic ranges and hints that the diversity of carnivorous dinosaurs has been underestimated. Full article

Uruguayan ammonoids are preserved in phosphate and siderite nodules found at the basalmost tillite-like conglomerates of the San Gregorio Formation. This lithostratigraphic unit was deposited under glacial conditions and its age (as well as that of the nodules) has been highly debated because glaciations were intermittent in Gondwana during the Late Paleozoic. Reef-builder organisms (e.g., Rugosa and Tabulata), goniatite and orthoceratid cephalopods, brachiopods, sponges, actinopterygians and other indeterminate gnatostomes, as well as fragmentary stems and roots of cf. Lycopsida are the most frequent fossils in the nodules. According to new biostratigraphic and paleoclimatic evidence, these taxa are representative of a reefal environment of a preliminary Devonian age including species that are common in the underlying Early Devonian (Emsian) Durazno Group. Among the ammonoid remains, more than 40 clusters of hatchling goniatites were found in the nodules. Each cluster contains a variable number of shells similar in shape to some of the adults also preserved within the nodules, representing a single species preserved at the same developmental stage (3 mm on size average). The strongly packed shells are enveloped by a substance with a different chemical composition and microstructure with respect to that of the nodule matrix, possibly indicating the presence of a gelatinous-like substance reminiscent of that secreted by the females of some extant cuttlefish and octopuses at the time of the egg spawn. Differing from previously described ammonoid accumulations, our clusters are unique in containing individuals of just a single species preserved in the same ontogenetic stage. That allows us to suggest that they represent a mode of reproduction in which hatchlings were morphologically similar to their parents and occupied the same habitat. Our results are thus one of the oldest known records of reproductive strategies in Paleozoic ammonoids and the phosphate and siderite nodules from the San Gregorio Formation are here classified as a new Konservat-Lagerstätte, which is the oldest known for South America. Full article

This study employs Principal Component Analysis to examine cranial measurements from both extant and fossil specimens spanning 38 species and comprising over 300 individuals within the subfamily Cervinae. Our findings elucidate craniometric distinctions among cervids characterized by varying body sizes and certain evolutionary adaptations. While our results generally corroborate previous assertions regarding the limited craniometric variability among plesiometacarpal deer, they also unveil specific cranial adaptations within certain genera and species. The Principal Component Analysis of craniometric data revealed that giant and large-sized deer display significantly broader ecomorphological diversity in cranial shape compared to small-sized deer. Secondly, small-sized deer exhibit greater uniformity in their cranial shape, appearing densely clustered on the factorial map. Thus, we conclude that body size imposes ecological constraints, limiting the available niches due to eco-physiological factors. This study demonstrates that endemic insular deer do not evolve consistent craniometric features attributable to insular isolation, while the cranial proportions of medium-to-small-sized deer delineate a ubiquitous morphological archetype characteristic of numerous cervid taxa spanning diverse phylogenetic lineages and sharing comparable body sizes. This group of “Dama-like” deer, characterized by similar body size, metabolic rates, ecological needs, and cranial morphometry, is referred to here as the fundamental eco-physiological type, typical of warm regions within the Palearctic and Oriental biogeographic realms. Full article

An articulated group of skeletal elements comprising a sacrum, both ilia and a first caudal vertebra, plus an isolated tooth found in immediate proximity to the bones, from the lower Cenomanian Chalk at Saint-Jouin-Bruneval (Seine-Maritime, Normandy, France) is described and attributed to a new genus and species of abelisaurid theropod, Caletodraco cottardi, on the basis of several characters of the sacrum and pelvis. The peculiar shape of the transverse process of the first caudal vertebra shows that Caletodraco cottardi differs from majungasaurine abelisaurids previously described from Europe, such as Arcovenator escotae, and belongs to the Furileusauria, a group of derived abelisaurids hitherto recognized only from South America. The presence of a furileusaurian abelisaurid in the Cenomanian of Normandy suggests that the biogeographical history of the Abelisauridae in Europe was more complex than hitherto admitted. Several previously described European abelisaurids, such as the Albian Genusaurus sisteronis, may in fact belong to the Furileusauria. Full article

Psocodea has been globally reported in different Mesozoic and Cenozoic amber deposits, one of which is Early Cretaceous Lebanese amber. The latter is one of the oldest ambers, with rich biological inclusions, bringing about the discovery of multiple new taxa of arthropods, some representing the earliest known records of their lineages. A total of fourteen psocodean species (of which one is an unidentified immature species) have been described to date from this material, which we review and discuss in this paper. A key for the identification of psocodean species discovered in Lebanese amber is also provided. Full article

In the Baltic States and Belarus, the Middle Devonian period is characterised by an abundant fossil record of invertebrates such as scolecodonts, brachiopods, ostracods, trilobites, bivalves, crinoids, gastropods, and tentaculites. On the other hand, there was limited diversity in the conodont and other vertebrate fauna. In this study, we introduce a newly refined ichthyofaunal assemblage from the Eifelian and Givetian epochs from the present-day regions of Belarus and Lithuania. The isolated scales of Cheirolepis are identified as C. gaugeri, C. cf. gaugeri, C. aleshkai, C. cf. aleshkai, and Cheirolepis sp., while Orvikuina is represented by the isolated scales of O. vardiaensis and Orvikuina sp. The histological analyses for the scales of Orvikuina are provided here. Moreover, Orvikuina and Cheirolepis taxa are now recognised to be widely distributed throughout the Baltic States, especially Lithuania and Belarus, as a result of these findings. Thus, this ichthyofaunal data markedly improved the biostratigraphic correlation within the study region and expanded the paleogeographic distribution of these taxa during the Eifelian and Givetian time in Laurasia. Full article

The Ediacaran–Cambrian deposits of Brittany (Brioverian series) contain both a few isolated pluricentimetric discoid structures, dome-shaped or “donut”-shaped, and a multitude of centimetric to infracentimetric more or less elliptical fossils or pseudofossils. The discoid and elliptical Brioverian structures are compared to similar fossils and pseudofossils found worldwide, and interpreted considering both sedimentary and biological hypotheses. This synthesis of more or less enigmatical fossils from the Ediacaran–Fortunian deposits of Brittany completes the previous descriptions of more well-known discoid and elliptical Brioverian structures such as Nimbia-like and Chuaria-like fossils. It provides a better understanding of the diversity of the Brioverian fossils and original sedimentary structures. Full article

Hymenoptera is the fourth-most diverse insect order today, including wasps, bees, bumblebees, and ants. They show a wide panoply of modes of life, such as herbivory, predation, parasitoidism, pollination, and eusociality. This group also includes a great number of extinct species from both amber and compression outcrops. Hymenopterans probably originated in the Paleozoic, although their oldest record is from the Middle or Late Triassic, and their diversity expanded since the Cretaceous. Here, we present a review of the Hymenoptera in Lower Cretaceous ambers from Lebanon (Barremian) and Spain (Albian), which is pivotal for the study of hymenopteran evolution. Hymenoptera in Lebanese ambers are represented by 32 species in 22 genera within 15 families, while in Spanish ambers, they correspond to 49 species in 40 genera within 18 families. Most of these species belong to the ‘Parasitica’, and only a few species have been assigned to the Aculeata. The group ‘Symphyta’ is represented by one species in Spanish amber. The paleobiogeography and possible paleobiologies of the species in these ambers are reviewed. Furthermore, checklists for all Hymenoptera species in Lebanese and Spanish ambers are provided. Full article