Femke Holwerda

Royal Tyrrell Museum of Palaeontology

Eusauropods are large-bodied and long-necked dinosaurs that dominated the role of large herbivores in terrestrial ecosystems since at least the late Early Jurassic (Pliensbachian–Toarcian). Their early diversification is best recorded in South America where the best-preserved eusauropods and close relatives from this period of time have been found....

Middle Jurassic sauropod taxa are poorly known, due to a stratigraphic bias of localities yielding body fossils. One such locality is Cerro Cóndor North, Cañadón Asfalto Formation, Patagonia, Argentina, dated to latest Early–Middle Jurassic. From this locality, the holotype of Patagosaurus fariasi Bonaparte 1986 is revised. The material consists of...

The Cretaceous Kem Kem beds of Morocco and equivalent beds in Algeria have produced a rich fossil assemblage, yielding, amongst others, isolated sauropod teeth, which can be used in species diversity studies. These Albian-Cenomanian (∼113–93.9 Ma) strata rarely yield sauropod body fossils, therefore, isolated teeth can help to elucidate the faunal...

Gondwanan Jurassic non-neosauropod eusauropods are key for the understanding of sauropod evolution, although their phylogenetic interrelationships remain poorly understood. However, following the revision of the holotype of a key taxon from the early Middle Jurassic Cañadón Asfalto Formation Patagonia, Argentina, Patagosaurus fariasi, the phylogene...

Dinosaur egg remains are relatively common in Campano-Maastrichtian deposits of the Aix-en-Provence in southern France. These fossils have been assigned to multiple oofamilies and ascribed to various dinosaur taxa found in the region, including nodosaurs (Cairanoolithidae), sauropods (Megaloolithidae, Fusioolithidae), and theropods (Montanoolithida...

The Morrison Formation of the western United States is well-known for its high diversity of sauropod dinosaurs. The Howe-Stephens Quarry in northern Wyoming is one of several quarries which has yielded several associated to completely articulated dinosaur specimens, among which a semi-articulated diplodocid specimen, MAB011899, which was excavated...

In this article, we document the widespread presence of bony ridges in the neural canals of non‐avian dinosaurs, including a wide diversity of sauropods, two theropods, a thyreophoran, and a hadrosaur. These structures are present only in the caudal vertebrae. They are anteroposteriorly elongate, found on the lateral walls of the canal, and vary in...

Nearly all dinosaur egg or oospecies occurrences from the Upper Cretaceous of France have been attributed to titanosaur dinosaurs. Here, we describe the first occurrence of probable hadrosauroid eggshells from France, which we assign to a new oospecies, Paraspheroolithus porcarboris oosp. nov. (oofamily: Spheroolithidae), from the upper 'Argiles et...

The Kem Kem Group of Southeastern Morocco, North Africa, is well known for theropod remains, especially isolated teeth. Here, a collection of isolated theropod teeth is assessed for diversity using a combination of linear discriminant, phylogenetic, and machine learning analyses for the first time. The results confirm earlier studies on Kem Kem the...

Mosasaurs (Squamata, Mosasauridae) were large aquatic reptiles from the Late Cretaceous that filled a range of ecological niches within marine ecosystems. The type-Maastrichtian strata (68–66 Ma) of the Netherlands and Belgium preserve remains of five species that seemed to have performed different ecological roles (carnivores, piscivores, durophag...

The Campanian sediments of the Bearpaw Formation yield a rich marine fauna from the northern exposures of the Western Interior Seaway. Many well-preserved mosasaur skeletons, representing most of the mosasaur taxa from this geological unit in Alberta, including skulls and dentition, are housed at the Royal Tyrrell Museum of Palaeontology. Good pres...

Although sauropodomorph dinosaurs have been known for a long time from the Late Triassic of central Europe, sauropodomorph diversity and faunal composition has remained controversial until today. Here we review sauropodomorph material from the Canton Schaffhausen, Switzerland. The material comes from three different but geographically close localit...

Preprint of In Press manuscript of the Osteological redescription of Patagosaurus fariasi

The Cretaceous Kem Kem beds, Morocco, are well-known for their theropod taxa (Spinosaurus, Carcharodontosaurus), but herbivores are rare, with a paucity in body fossils. Their teeth are more abundant, though not as numerous as for theropods. These teeth are used as paleoenvironmental proxies. Because dental enamel incorporates trace elements via wa...

Dinosaur body fossilmaterial is rare in Scotland, previously known almost exclusively from the Great Estuarine Group on the Isle of Skye. We report the first unequivocal dinosaur fossil from the Isle of Eigg, belonging to a Bathonian (Middle Jurassic) taxon of uncertain affinity. The limb bone NMS G.2020.10.1 is incomplete, but through a combinatio...

We continue our trip back in time through the Mesozoic, visiting several different ecosystems across the planet. Each of these was strongly influenced by the continental breakup from a single landmass into several tectonic plates and associated landmasses during this period. We will visit localities on several continents, observe how their vertebra...

Eine internationale Forschergruppe beschreibt in der aktuellen Ausgabe des Swiss Journal of Geosciences einen für die Wissenschaft neuen Dinosaurier aus dem Kanton Schaffhausen unter dem Namen Schleitheimia schutzi. Dabei stützen sich die Wissenschaftler sowohl auf ältere Funde eines lokalen Sammlers als auch auf Fossilien aus einer Grabung im Jahr...

Four isolated sauropod axial elements from the Oxford Clay Formation (Callovian, Middle Jurassic) of Peterborough, UK, are described. Two associated posterior dorsal vertebrae show a dorsoventrally elongated centrum and short neural arch, and nutrient or pneumatic foramina, most likely belonging to a non-neosauropod eusauropod, but showing ambiguou...

The Cretaceous Kem Kem beds of Morocco and equivalent beds in Algeria have produced a rich fossil assemblage, yielding, amongst others, isolated sauropod teeth, which can be used in species diversity studies. These Albian-Cenomanian (~113 – 93.9 Ma) strata rarely yield sauropod body fossils, therefore, isolated teeth can help to elucidate the fauna...

A set of associated left pedal elements of a sauropod dinosaur from the Upper Jurassic Morrison Formation in Weston County, Wyoming, is described here. Several camarasaurids, a nearly complete small brachiosaur, and a small diplodocid have been found at this locality, but none match the exceptionally large size of the pedal elements. Next to the as...

Eusauropod metatarsal V elongation Red ratios are based on measurements taken from figures.

Titanosaurs were the last-surviving group of sauropod dinosaurs, having persisted until the end-Cretaceous. Since the early 21st century, knowledge of this diverse and cosmopolitan group of dinosaurs has greatly improved, although many aspects of their biology and evolutionary history remain poorly understood. In particular, knowledge of Late Creta...

The Late Cretaceous (Cenomanian, 100.5Ma – 93.9Ma) Kem Kem beds of Morocco and equivalent beds in Algeria have produced a rich fossil assemblage, yielding, among others, many isolated teeth which can be used in species diversity studies. As this area is rare in herbivore body fossils, these isolated teeth provide a different approach to analyzing p...

Eusauropods were a group of herbivorous dinosaurs that evolved during the Early Jurassic and dominated the terrestrial ecosystems throughout the Jurassic and Cretaceous. A peak of diversity is represented by the Late Jurassic, when most of the lineages of the derived clade, Neosauropoda, are represented. Different lineages of eusauropods differ in...

The Callovian Oxford Clay of England has yielded a rich and diverse marine fauna, mainly discovered and described by Alfred Leeds. However, occasionally it also brought forth terrestrial fossils, including four isolated cases of sauropod remains, one of a stegosaurid, and another of a dryosaurid. Thus far, only Cetiosaurus oxoniensis and Cetiosauri...

The Callovian Oxford Clay of England has yielded a rich and diverse marine fauna, mainly discovered and described by Alfred Leeds. However, occasionally it also brought forth terrestrial fossils, including four isolated cases of sauropod remains, one of a stegosaurid, and another of a dryosaurid. Thus far, only Cetiosaurus oxoniensis and Cetiosauri...

Upper Maastrichtian to lower Paleocene, coarse-grained deposits of the Lefip an Formation in Chubut Province , (Patagonia, Argentina) provide an opportunity to study environmental changes across the Cretaceous–Palaeo-gene (K–Pg) boundary in a shallow marine depositional environment. Marine palynological and organic geochemical analyses were perform...

During the Late Cretaceous, mosasaurs were successful marine reptiles, achieving a worldwide distribution and occupying a wide array of ecological niches. Recent research has aided in identifying the feeding guilds of the various mosasaur taxa. In the type area of the Maastrichtian Stage (southeast Netherlands, northeast Belgium), five species are...

The early Middle Jurassic is regarded as the period when sauropods diversified and became major components of the terrestrial ecosystems. Not many sites yield sauropod material of this time; however, both cranial and postcranial material of eusauropods have been found in the Cañadón Asfalto Formation (latest Early Jurassic–early Middle Jurassic) in...

OSTEOLOGICAL REVISION OF THE HOLOTYPE OF PATAGOSAURUS FARIASI, A BASAL EUSAUROPOD FROM ARGENTINA HOLWERDA, Femke, Bavarian State collection for Paleontology and Geology/ LMU, Munich, Germany; RAUHUT, Oliver, Bayerische Staatssammlung fur Palaontologie und Geologie, Munchen, Germany; POL, Diego, CONICET-MPEF, Trelew, Argentina The sauropod dinosaur...

Teeth of the small durophagous mosasaur Carinodens belgicus are known from Maastrichtian Atlantic-Tethyan deposits worldwide. The peculiar dentition of Carinodens inspired debate and speculation on its dietary niche ever since its first description. In this contribution, we describe the macro- and microwear pattern in five well-preserved isolated t...

Dinosaur eggs and eggshells of Jurassic age or older are relatively rare worldwide when compared with Cretaceous ones. However, the Lourinha region in central-west Portugal is rich in Kimmeridgian-Tithonian dinosaur egg- and eggshell localities, two with associated theropod embryo material of Lourinhanosaurus and another large theropod. Here, we de...

Two new Late Jurassic (uppermost Late Kimmeridgian) dinosaur eggshell sites are described, Casal da Rola and Porto das Barcas, both near Lourinha˜, central-west Portugal. Casal da Rola yields eggshells with an obliquiprismatic morphotype comparable to those from a nest with the associated fossil embryos from Paimogo, tentatively assigned to the the...

In order to clarify the nature of the Cretaceous-Paleogene (K-Pg) transition at southern high latitudes, quantitative marine palynological analysis has been performed on samples from the Lefipan Formation (province of Chubut, Patagonia, Argentina). The shallow marine/estuarine nature of the succession prohibits the occurrence of age-diagnostic biot...