[Paleontology • 2026] Foskeia pelendonum • A New rhabdodontomorph from the Lower Cretaceous of Salas de los Infantes (Burgos Province, Spain), and a new phylogeny of ornithischian dinosaurs

Foskeia pelendonum

Dieudonné, Becerra, Zanesco, Tortosa, Cruzado-Caballero, Stein & Fernández-Baldor, 2026 

DOI: doi.org/10.1002/spp2.70057 

 facebook.com/novataxa

reconstruction by Martina Charnell

 

Abstract

The Vegagete ornithopod is a diminutive bipedal iguanodont from the upper Barremian to lower Aptian (Lower Cretaceous) Castrillo de la Reina Formation of the Burgos Province (Spain). This dinosaur is principally known from disarticulated and fragmentary postcranial remains and was established as the earliest rhabdodontomorph. However, the nature of this material did not allow formal diagnosis of what still appeared to be a new taxon due to its particularly small body size. Recently, new cranial elements have been identified. These elements underwent micro-computed tomography scanning, segmentation and three-dimensional assembly. We herein name the Vegagete ornithopod Foskeia pelendonum gen. et sp. nov. It is diagnosed by a high number of unique features such as the possession of fused premaxillae, procumbent premaxillary teeth, one filiform first dentary tooth, and an elevated craniomandibular joint. Simultaneously, we observe a unique ventrolateral extension of the insertion of the muscle adductor mandibulae externus superficialis on the coronoid process of the dentary. Answering a number of phylogenetic controversies, we provide an updated, taxonomically augmented ornithischian phylogeny toward poorly sampled regions of the ornithischian tree. Rhabdodontia nov. is defined as a restricted clade of European rhabdodontomorphs, including F. pelendonum and rhabdodontids. Rhabdodontomorpha is nested to the base of Ankylopollexia. Thescelosauridae includes Tenontosaurus, and Dryosauridae includes Elasmaria. Agilisaurus louderbacki and Minimocursor phunoiensis are basal ornithopods. Heterodontosauridae remains at the base of Pachycephalosauria. Silesauridae and Sauropodomorpha are resolved in a position closer to Ornithischia than to Theropoda. This provisional result is pending the inclusion of more saurischian characters and taxa.

Keywords: Rhabdodontia, Rhabdodontomorpha, Ornithopoda, Ornithischia, phylogeny

Reconstruction of the skull of Foskeia pelendonum based on different elements.

Foskeia pelendonum.

PaleoArt reconstruction by Martina Charnell

Growth trajectory of Foskeia pelendonum, compared to an adult chicken.
This trajectory is based on differently sized bony elements and their histology.
Note the proportionally smaller forelimbs in the more mature individuals.  

 

Paul-Emile Dieudonné, Marcos Gabriel Becerra, Tábata Zanesco, Thierry Tortosa, Penélope Cruzado-Caballero, Koen Stein, Fidel Torcida Fernández-Baldor. 2026. Foskeia pelendonum, A New rhabdodontomorph from the Lower Cretaceous of Salas de los Infantes (Burgos Province, Spain), and a new phylogeny of ornithischian dinosaurs. Papers in Palaeontology. 12(1); e70057. DOI: doi.org/10.1002/spp2.70057 [01 February 2026]

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[Paleontology • 2025] Ahshislesaurus wimani • A New saurolophine hadrosaurid (Ornithischia: Hadrosauridae) from the Upper Cretaceous (Campanian) Hunter Wash Member, Kirtland Formation, San Juan Basin, New Mexico

Ahshislesaurus wimani 

Dalman, Jasinski, Malinzak, Malinzak, Lucas, Kundrát, Fiorillo, 2025

 

 Researchgate.net/publication/396005330

Artwork by Sergey Krasovskiy

A new saurolophine hadrosaurid dinosaur, Ahshislesaurus wimani gen et sp. nov., from the lower Hunter Wash Member of the lower Kirtland Formation (~75.02 Ma) of New Mexico is described. The specimen was briefly described before and referred to the stratigraphically younger Kritosaurus navajovius, which is known from the De-na-zin Member (~73.83–73.49 Ma) of the uppermost Kirtland Formation. The holotype of A. wimani consists of an incomplete diagnostic skull, several isolated cranial elements including the right jugal, quadrate, dentary, and surangular, and a series of articulated cervical vertebrae. In addition to the holotype of A. wimani, several specimens from the same strata may also belong to this newly identified species, including a well-preserved left dentary and a partial skeleton, as well as two humeri, one belonging to a large adult and the other to a juvenile. The skull of A. wimani preserves several taxonomically informative characters that show close affinities with the stratigraphically younger Naashoibitosaurus ostromi from the De-na-zin Member. Together with Naashoibitosaurus, Ahshislesaurus forms a potentially novel clade of flat-headed saurolophine hadrosaurids. This clade suggests the saurolophines were a taxonomically diverse group, which, during the last 20 million years of the Cretaceous, were among the dominant herbivorous dinosaurs in southern Laramidia. Recognition of a new hadrosaurid species from New Mexico also provides further evidence for latitudinal variation in the hadrosaurid fauna during the Late Cretaceous in Laramidia.

Skeleton reconstruction of Ahshislesaurus wimani gen. et sp. nov., (USNM VP-8629), holotype skull.
This includessome of the postcranial specimens from the lower Hunter Wash Member (Kirtland Formation) that may not represent this newspecies, including a postcranial skeleton (NMMNH P-25057); left scapula (NMMNH P-RMS 2013-7); left humerus (NMMNHP-31928); and right isolated ulna (NMMNH P-32885).

SYSTEMATIC PALEONTOLOGY

DINOSAURIA Owen, 1842

ORNITHISCHIA Seeley, 1887

ORNITHOPODA Marsh, 1881

IGUANODONTIA Dollo, 1888

HADROSAURIA von Huene, 1956

HADROSAURIDAE Cope, 1870

SAUROLOPHINAE Brown, 1914

Ahshislesaurus, new genus

Etymology: The genus name Ahshislesaurus is from the Ah-shi-sle-pah Wash Wilderness in the lower Hunter Wash Member of the Kirtland Formation in northwestern New Mexic where the new species was found. Ah-shi-sle-pah Wildernessis located in San Juan County, New Mexico, between Chaco Canyon and the De-na-zin Wilderness. Its name is a phonetic transliteration of Navajo “áshįįh łibá” meaning “salt, it is gray.”.

Ahshislesaurus wimani, new species 

Etymology: The specific epithet, wimani, honors the first Swedish professor of paleontology, Carl Wiman (1867–1944),from Uppsala University, who worked on fossil vertebrates from the San Juan Basin. 

Life reconstruction of Ahshislesaurus wimani gen. et sp. nov. based on the holotype (USNM VP-8629) and closely related taxa.

Artwork by Sergey Krasovskiy

Sebastian G Dalman, Steven E. Jasinski, D Edward Malinzak, ... et Anthony R. Fiorillo. 2025. A New saurolophine hadrosaurid (Ornithischia: Hadrosauridae) from the Upper Cretaceous (Campanian) Hunter Wash Member, Kirtland Formation, San Juan Basin, New Mexico. New Mexico Museum of Natural History and Science Bulletin. Fossil Record. 11: 73–114. (September 2025)  

 Researchgate.net/publication/396005330_A_new_saurolophine_hadrosaurid_from_the_Upper_Cretaceous_Hunter_Wash_Member_Kirtland_Formation_San_Juan_Basin_New_Mexico

[Paleontology • 2025] Cariocecus bocagei • A New basal hadrosauroid from the Lower Cretaceous of Portugal

 Cariocecus bocagei

Bertozzo, Camilo, Araújo, Manucci, Kullberg & Cerio, 2025

 

 DOI: doi.org/10.1080/14772019.2025.2536347  

  facebook.com: Bruno Camilo Silva   

Artwork by Victor F. Carvalho  

Abstract

In Portugal, iguanodontian dinosaurs are mostly known from the Late Jurassic of the Lourinhã Formation and are represented by dryosaurids and basal styracosternans. The Early Cretaceous record of iguanodontians in Portugal is scarce in comparison, with scattered and uninformative remains referred to Styracosterna indet. Here, we describe SHN.832, the first iguanodontian skull from Portugal, named Cariocecus bocagei gen. nov. sp. nov. The specimen was found in Praia do Areia do Mastro (Cabo Espichel, Sesimbra) in the Papo Seco Formation (lower Barremian), and comprises the right side of the skull, part of the skull vault and a nearly complete basicranium. Cariocecus bocagei is diagnosed based on autapomorphies such as the co-ossified maxillo-jugal complex and the trilobated shape of the supraoccipital. The phylogenetic analysis retrieves C. bocagei as a basal hadrosauroid in a clade with Comptonatus chasei and Brighstoneus simmondsi. Our biogeographical analysis emphasizes the effects of insular endemism during the Hauterivian–Aptian range in the European regions. We show that Iguanodontia originated in South America, and through a dispersal event towards North America during the Upper Jurassic, expanded their latitudinal range. Cariocecus and other early-diverging iguanodontians emerged during an eastward dispersal event in the Lower Cretaceous. We reconstructed the endocast, cranial nerves and inner ear of Cariocecus via segmentation of micro-computed tomography scanning, showing similarities with other Hadrosauriformes such as Iguanodon and Proa. We propose the most detailed inner ear soft-tissue reconstruction for a dinosaur so far, including the macula and sub-branches of the vestibulocochlear nerve, supported by the extant phylogenetic bracket. Based on the unossified suture of the cranial elements, we hypothesize that SHN.832 had not yet reached full skeletal maturity, and our restoration suggests a total skull length of about 45 cm. The supraorbital membrane was reconstructed based on the well-preserved supraorbital bone and comparison with modern taxa. 

Keywords: Ornithopoda, Barremian, Papo Seco Formation, supraorbital, biogeography

 

Cariocecus bocagei gen. nov. sp. nov. 

  

 

Filippo Bertozzo, Bruno Camilo, Ricardo Araújo, Fabio Manucci, José Carlos Kullberg, Donald G. Cerio. 2025. Cariocecus bocagei, A New basal hadrosauroid from the Lower Cretaceous of Portugal. Journal of Systematic Palaeontology. 23(1); 2536347. DOI: doi.org/10.1080/14772019.2025.2536347 [15 Sep 2025] 

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[Paleontology • 2025] Istiorachis macarthurae • The Origins of Neural Spine Elongation in iguanodontian dinosaurs and the Osteology of A New sail-back styracosternan (Ornithischia: Iguanodontia) from the Lower Cretaceous Wealden Group of England

Istiorachis macarthurae  

Lockwood, Martill & Maidment, 2025 

 

DOI: doi.org/10.1002/spp2.70034 

Original artwork by James Brown.

Abstract

The Wealden Group of southern England was deposited during the late Berriasian to early Aptian interval. It records a critical time in the development of iguanodontian dinosaur diversity, which increased from low levels during the Jurassic to higher levels in the Aptian and Albian. A new iguanodontian dinosaur, Istiorachis macarthurae gen. et sp. nov. from the Wessex Formation (Wealden Group) of the Isle of Wight, exhibits hyperelongation of the dorsal and caudal neural spines, suggesting that it possessed a possible sail structure. Ancestral state reconstruction for the relative height of dorsal neural spines in iguanodontians demonstrates that modest elongation began with Ankylopollexia in the Late Jurassic and elongation became established during the Berriasian stage of the Early Cretaceous, albeit with widely disparate values. Hyperelongation of neural spines occurred more sporadically throughout the Cretaceous, being recorded most often in the Barremian and early Aptian. Possible explanations for neural spine elongation in Ankylopollexia include biomechanical advantage, perhaps related to greater mass and a locomotory shift towards quadrupedalism, and visual signalling driven either by sexual selection or species recognition, or both. The function of elongate neural spines was probably pluralistic and differed in different taxa. No single explanation fully supports the variation seen throughout the Cretaceous.

Keywords: Iguanodontia, diversity, sexual signalling, Isle of Wight, ossified tendons, Barremian

SYSTEMATIC PALAEONTOLOGY

DINOSAURIA Owen 1842

ORNITHISCHIA Seeley 1888

ORNITHOPODA Marsh 1881

IGUANODONTIA Baur 1891

ANKYLOPOLLEXIA Sereno 1986

STYRACOSTERNA Sereno 1986

Genus Istiorachis nov.

Derivation of name: The name is derived from the Ancient Greek words ἱστίον (istion), meaning a sail, and ῥάχις (rachis), the spine or backbone. It refers to the probable sail-back appearance of the dinosaur.

Istiorachis macarthurae sp. nov.

 

Derivation of name: The species name honours Dame Ellen MacArthur, an English sailor who in 2005 set a world record for the fastest solo non-stop voyage around the world on her first attempt and who also founded the Ellen MacArthur Cancer Trust for young people on the Isle of Wight.

Holotype: MIWG 6643 is a partial skeleton composed of the following elements: one cervical vertebra, eight dorsal vertebrae, three dorsal rib heads, a partial sacrum, seven caudal vertebrae, both pubes and both ischia.

Location & horizon: MIWG 6643 was excavated by the late Mr Nicholas Chase from the ‘Black Band’ (bed L11 in Stewart 1978), a plant debris bed cropping out c. 100 m east of Grange Chine, lying above the Grange Chine Sandstone in the Wessex Formation. The site is a c. 1.5-m-thick bed that has occasionally yielded dinosaur remains, including IWCMS 1997.550, the holotype specimen of the tyrannosauroid theropod Eotyrannus lengi (Hutt et al. 2001; Naish & Cau 2022). Unfortunately the excavation site was poached and an unknown amount of the skeleton was taken before collection could be completed.

Diagnosis: Istiorachis macarthurae differs from all other iguanodontians by possessing one autapomorphy, namely two anterior parasagittal tuberosities present on the ventral surface of a posterior dorsal vertebra, marking a change from vertebrae with a ventral keel to a flat surface. A posterior cervical vertebra has a damaged anteroventral process at the base of the neural spine, potentially representing a second autapomorphy. Istiorachis macarthurae also possesses the following features, which, although not unique to the taxon, occur in a unique character combination. An interpostzygapophyseal fossa and tubular cavity is located between the origin of the postzygapophyses and above the neural canal: a similar fossa is also seen in ...

Istiorachis macarthurae gen. et sp. nov. (MIWG 6643). Life restoration.
Original artwork by James Brown.

Istiorachis macarthurae gen. et sp. nov. holotype (MIWG 6643).
Skeletal reconstruction. Scale bar represents 500 mm.

 

Jeremy A. F. Lockwood, David M. Martill and Susannah C. R. Maidment. 2025.  The Origins of Neural Spine Elongation in iguanodontian dinosaurs and the Osteology of A New sail-back styracosternan (Dinosauria, Ornithischia) from the Lower Cretaceous Wealden Group of England. Papers in Palaeontology. DOI: doi.org/10.1002/spp2.70034 [21 August 2025]

[Paleontology • 2025] Neonatal State and Degree of Necessity for Parental Care in Maiasaura based on inferred Neonatal Metabolic Rates

The hatching of hadrosaurid dinosaur Maiasaura peeblesorum  

in Bert, Woodward, Rinder, Amiot, ... et Cubo, 2025. 

DOI: doi.org/10.1038/s41598-025-06282-5 

 www.insu.CNRS.fr

Artwork by Delphine Zigoni linkedin.com: Delphine Zigoni 

Abstract 

We infer the neonatal metabolic rate at rest (RMR) and at maximum activity levels (MMR) of the hadrosaurid dinosaur Maiasaura peeblesorum from the Two Medicine Formation of Montana (USA) using Phylogenetic Eigenvector Maps applied to the following osteohistological features: the Relative Primary Osteon Area and the size of the femoral nutrient foramen as proxies. We investigate the locomotor/motor activity of the neonates by comparing the difference between maximum and minimum rates of oxygen consumption—referred to as aerobic scope and denoted as ΔMR, as a proxy of their activity levels. Applied to Maiasaura, this novel methodology allows for a quantitative assessment of its neonatal state and to deduce its dependence on parental care. The inferred neonatal RMR values for Maiasaura are similar to those of present-day fast-growing endotherms. As for the aerobic scope, M. peeblesorum neonates have a ΔMR value similar to those observed in present-day altricial birds that need intensive parental care. This result is consistent with the previously proposed hypothesis of nidicolous M. peeblesorum requiring parental care. Finally, based on age-estimations from M. peeblesorum neonate remains found both in and outside nest sites, we estimate that this species remained in the nest for approximately 40–75 days. Maiasaura provides a useful ecological baseline from which to infer neonatal states in an other hadrosaur of similar adult size—Hypacrosaurus stebingeri, whose differing ecological traits point to a relatively more precocial condition. The diversity of post-hatching reproductive strategy partly explains the adaptation of hadrosaurs to a wide range of paleolatitudes and environments.

Keywords: Relative primary osteon area, Nutrient foramina, Phylogenetic eigenvector maps, Reproductive strategy

 

Hugo Bert, Holly Woodward, Nicolas Rinder, Romain Amiot, John R. Horner, Christophe Lécuyer, Mariana Sena and Jorge Cubo. 2025. Neonatal State and Degree of Necessity for Parental Care in Maiasaura based on inferred Neonatal Metabolic Rates. Scientific Reports. 15: 24827. DOI: doi.org/10.1038/s41598-025-06282-5 [10 July 2025]

www.insu.CNRS.fr/fr/cnrsinfo/dinosaure-maiasaura-la-pratique-de-soins-parentaux-confirmee-par-lanalyse-micro-anatomique

https://fr.linkedin.com/posts/delphine-zigoni-b929b4163_il-y-a-quelques-semaines-jai-réalisé-cette-activity-7325252099984814080-rlj8

[Paleontology • 2025] Obelignathus septimanicus • Exploring the Diversity and Disparity of rhabdodontomorph Ornithopods from the Late Cretaceous European Archipelago

  

Obelignathus septimanicus  Buffetaut & Le Loeuff, 1991

in Czepiński et Madzia, 2025. 

DOI: doi.org/10.1038/s41598-025-98083-z  

 facebook.com/LukaszCzepinski 

  x.com/DanielMadzia

 Artwork by Edyta Felcyn-Kowalska

Abstract

The origin and early diversification of ornithopods, a major clade of ornithischian dinosaurs, remain poorly understood, with conflicting phylogenetic hypotheses regarding rootward neornithischian relationships. Some topological stability is inferred near the basal divergence of Iguanodontia, though the ingroup relationships remain unclear. For instance, Rhabdodontidae, a clade of Late Cretaceous European ornithopods ‘traditionally’ considered to include eight to nine species, presents significant taxonomic challenges. We explore the diversity and disparity of European Rhabdodon-lineage iguanodontians. We assembled a novel dataset comprising morphological and morphometric data obtained from rhabdodontomorph dentaries, which are abundant, well-preserved in the majority of the taxa, and distinctive. Special attention is given to Rhabdodon septimanicus, a poorly known taxon from the upper Campanian to lower Maastrichtian of southern France, established based on a particularly robust dentary bone that has been subjected to conflicting taxonomic interpretations. Our restudy of the specimen, combined with a multivariate and phylogenetic assessment, shows that this taxon is a clear morphological outlier among European rhabdodontomorphs, providing a basis for its assignment to a new genus, Obelignathus. Although further large-scale studies, especially detailed osteological descriptions, are needed to clarify the taxonomic significance of certain European rhabdodontomorphs, our results indicate that the group exhibits greater diversity than currently recognized, with several sympatric taxa co-occurring, at least in southern France and possibly also in Romania.

Obelignathus septimanicus gen. et comb. nov. holotype, MDE D30 from the ‘Grès à Reptiles’ Formation of Montouliers, southern France.
Photographs and photogrammetric models of the right dentary in dorsal (A), anterior (B), medial (C), and lateral (D) views.

Life restoration of Obelignathus septimanicus gen. et comb. nov. in the Late Cretaceous environment recorded in the ‘Grès à Reptiles’ Formation, with a pair of dromaeosaurid dinosaurs in the background.

 Artwork by Edyta Felcyn-Kowalska (CC BY 4.0).

 

Łukasz Czepiński and Daniel Madzia. 2025. Exploring the Diversity and Disparity of rhabdodontomorph Ornithopods from the Late Cretaceous European Archipelago. Scientific Reports. 15: 15209. DOI: doi.org/10.1038/s41598-025-98083-z [30 April 2025]

  facebook.com/LukaszCzepinski/posts/10238804784762400

  x.com/DanielMadzia/status/1917550382626267474

  

[Paleontology • 2025] Emiliasaura alessandrii • First Valanginian (Early Cretaceous) Ornithopod (Ornithischia: Ornithopoda) from Patagonia

  

Emiliasaura alessandrii

R.A. Coria, Cerda, Escaso, Baiano, Bellardini, Braun, L.M. Coria, Gutierrez, Pino, Windholz, Currie & Ortega, 2024 

DOI: 10.1016/j.cretres.2024.106027

Highlights: 

• A new taxon of the dinosaur clade Ornithopoda, Emiliasaura alessandri, is described.

• Emiliasaura is the first recognized South American rhabdodontoid ornithopod taxon.

• Emiliasaura represents the earliest Patagonian Cretaceous ornithischian dinosaur.

Abstract

Here we describe a new ornithopod species, Emiliasaura alessandrii gen. et sp. nov. from Valanginian rocks (Early Cretaceous) of northwestern Patagonia. This new taxon exhibits affinities with the Rhabdodontomorpha and is primarily represented by two specimens of mid-sized ornithopods collected from different sites and stratigraphical levels of the Mulichinco Formation. The holotype specimen MLL-Pv-001 includes the coracoid, the proximal end of a scapula, a humerus and a complete right hind limb, whereas the paratype specimen MLL-Pv-006 preserves vertebral elements, haemal arches, an incomplete pelvis, and nearly complete hind limbs. The new taxon has an anteroposteriorly elongate ilium with a sigmoidal dorsal border and broad brevis shelf, a femur shaft with an extensive, proximally positioned fourth trochanter, and a second pedal digit with a short, robust, blunt ungual phalanx similar to those in Ankylopollexia ornithopods. The new ornithopod taxon formed part of a diverse dinosaur association from the Mulichinco Fm that includes dicraeosaurid sauropods and carcharodontosaurid theropods, and represents the first South American record of a rhabdodontoid, and the oldest and most primitive representative of this clade.

 

Emiliasaura alessandrii gen. et sp. nov. 

R.A. Coria, I.A. Cerda, F. Escaso, M.A. Baiano, F. Bellardini, A. Braun, L.M. Coria, J.M. Gutierrez, D. Pino, G.J. Windholz, P.J. Currie and F. Ortega. 2024. First Valanginian (Early Cretaceous) Ornithopod (Dinosauria, Ornithischia) from Patagonia. Cretaceous Research. 106027. DOI: doi.org/10.1016/j.cretres.2024.106027

[Paleontology • 2024] Coahuilasaurus lipani • a New Kritosaurin Hadrosaurid (Hadrosauridae: Saurolophinae) from the Upper Campanian Cerro Del Pueblo Formation, Northern Mexico

Coahuilasaurus lipani

Longrich, Velasco, Kirkland, Torres & Serrano-Brañas, 2024

 

DOI: 10.3390/d16090531  

Life reconstruction by C. Díaz Frías

Abstract

The Late Cretaceous of Western North America (Laramidia) supported a diverse dinosaur fauna, with duckbilled dinosaurs (Hadrosauridae) being among the most speciose and abundant members of this assemblage. Historically, collecting and preservational biases have meant that dinosaurs from Mexico and the American Southwest are poorly known compared to those of the northern Great Plains. However, evidence increasingly suggests that distinct species and clades inhabited southern Laramidia. Here, a new kritosaurin hadrosaurid, represented by the anterior part of a skull, is reported from the late Campanian of the Cerro del Pueblo Formation, ~72.5 Ma, in Coahuila, Mexico. The Cerro del Pueblo Formation kritosaur was originally considered to represent the same species as a saurolophine from the Olmos Formation of Sabinas, but the Sabinas hadrosaur is now considered a distinct taxon. More recently, the Cerro del Pueblo Formation kritosaur has been referred to Kritosaurus navajovius. We show it represents a new species related to Gryposaurus. The new species is distinguished by its large size, the shape of the premaxillary nasal process, the strongly downturned dentary, and massive denticles on the premaxilla’s palatal surface, supporting recognition of a new taxon, Coahuilasaurus lipani. The dinosaur assemblage of the Cerro del Pueblo Formation shows higher diversity than the contemporaneous fauna of the Horseshoe Canyon Formation in Alberta. Furthermore, Kritosaurini, Lambeosaurini, and Parasaurolophini all persist into the latest Campanian in southern Laramidia after disappearing from northern Laramidia. These patterns suggest declining herbivore diversity seen at high latitudes may be a local, rather than global phenomenon, perhaps driven by cooling at high latitudes in the Late Campanian and Maastrichtian.

Keywords: Dinosauria; Hadrosauridae; Saurolophinae; Kritosaurini; Cretaceous; Campanian; Laramidia; biogeography

 IGM 6685, holotype Coahuilasaurus lipani. (A), rostrum with posterior skull reconstructed in left lateral view; (B), scaled silhouette. The animal is estimated to have been around 8 m in length.

Dinosauria Owen 1842

Ornithopoda Marsh 1881 

Hadrosauridae Cope 1869 

Saurolophinae Brown 1914 (sensu Prieto-Márquez, 2010)

Kritosaurini Brett-Surman 1989 (sensu Prieto-Márquez, 2014)

Coahuilasaurus lipani gen. et sp. nov.

Etymology. Coahuila in reference to Coahuila State + Greek sauros, ‘lizard’; lipani references the Lipani Apache tribe of Coahuila.

Diagnosis. Large kritosaurin with an estimated length of ~8 m (Figure 5). Distinguished by the following unique character combination (* = autapomorphies). The anterior margin of premaxillae is strongly convex in lateral view; the anterodorsal margin of the narial process is subtly sinusoidal in lateral view, being concave anteriorly then weakly convex posteriorly *. The narial aperture is narrow and slot-like and strongly extended anteroventrally *. The premaxillary labrum is deep anteriorly, becoming shallower posteriorly. The posteroventral corner of the premaxillary beak is strongly angular, with the anteroventral margin and posteroventral margin forming approximately a right angle in lateral view *; the posteroventral margin of the premaxilla is strongly concave in lateral view. The premaxilla is short and broad in dorsal view. The oral margin of the beak bears a series of 5–6 small denticles. The palatal surface of the premaxilla forms a horseshoe-shaped ridge projecting far below the oral margin *; the ridge bears three pairs of massive, diamond-shaped denticles*. The nasal–premaxillary contact is posteriorly positioned, probably near the end of the nasal aperture. Very large narial flange of premaxilla *. The predentary oral margin is strongly concave in the lateral view and has a steeply inclined rostroventral margin, and the tip is hooked up strongly in lateral view (approached in Gryposaurus monumentensis). There is a narrow U-shaped notch between predentary lateral processes and ventral processes (shared with Gryposaurus monumentensis); the ventral processes are long and slender. The edentulous end of the dentary is strongly downturned, with a strongly convex anterodorsal margin, and a long ventral contact between the dentaries.

 

 Map showing localities of kritosaurins from the Late Cretaceous of western North America (Laramidia).
1,2, Gryposaurus notabilis (incl. G. incurvimanus) Dinosaur Park Formation, Alberta; 3, Gryposaurus latidens, Two Medicine Formation, Montana; 4, Gryposaurus sp., Bearpaw Shale, Montana; 5, Kritosaurini indet., North Horn Formation, Utah;
6, Rhinorex condrupus, Neslen Formation, Utah; 7, Gryposaurus monumentensis, Kaiparowits Formation, Utah; 8, Anazisaurus horneri, Farmington Formation of the Kirtland Formation of New Mexico; 9, Naashoibitosaurus ostromi, De-Na-Zin Member of the Kirtland Formation of New Mexico; 10, Kritosaurus navajovius, De-Na-Zin Member of the Kirtland Formation of New Mexico;
11, Naashoibito kritosaurin, Naashobito Member of the Kirtland Formation of New Mexico; 12, Gryposaurus (?) alsatei, upper Javelina Formation, Texas; 13, cf. Kritosaurus, UTEP P.37.7, basal Javelina Formation of Texas; Aguja Formation, Texas; 14, Aguja Fm. Kritosaur, AMNH 3079; 15, Coahuilasaurus lipani, Cerro del Pueblo Formation, Coahuila. Map by Ron Blakey.

Conclusions: 

A partial skull from the latest Campanian of the Cerro del Pueblo Formation of Coahuila, Mexico, represents a new species of kritosaurin, Coahuilasaurus lipani (Figure 20). Along with specimens from the Naashoibito Member of the Kirtland Formation in New Mexico, C. lipani documents the persistence of kritosaurins in the south after local extinction in northern Laramidia, a pattern also seen in Parasaurolophini and Lambeosaurini.

Southern faunas not only have distinct species, but different patterns of diversity change, compared to northern Laramidian faunas. Differences in species composition and community structure in different parts of Laramidia mean that further work on the dinosaurs of Mexico and the American Southwest is needed to understand the evolution of dinosaur diversity in western North America. Southern dinosaur faunas may have been characterized by both higher origination rates and lower extinction rates than northern faunas.

 Nicholas R. Longrich, Angel Alejandro Ramirez Velasco, Jim Kirkland, Andrés Eduardo Bermúdez Torres and Claudia Inés Serrano-Brañas. 2024. Coahuilasaurus lipani, a New Kritosaurin Hadrosaurid from the Upper Campanian Cerro Del Pueblo Formation, Northern Mexico. Diversity. 16(9), 531. DOI: doi.org/10.3390/d16090531  

[Paleontology • 2024] Fona herzogae • A New semi-fossorial thescelosaurine Dinosaur (Neornithischia: Thescelosauridae) from the Cenomanian-age Mussentuchit Member of the Cedar Mountain Formation, Utah

Fona herzogae

Avrahami, Makovicky, Tucker & Zanno, 2024

 

DOI: 10.1002/ar.25505

Abstract

Thescelosaurines are a group of early diverging, ornithischian dinosaurs notable for their conservative bauplans and mosaic of primitive features. Although abundant within the latest Cretaceous ecosystems of North America, their record is poor to absent in earlier assemblages, leaving a large gap in our understanding of their evolution, origins, and ecological roles. Here we report a new small bodied thescelosaurine—Fona herzogae gen. et sp. nov.—from the Mussentuchit Member of the Cedar Mountain Formation, Utah, USA. Fona herzogae is represented by multiple individuals, representing one of the most comprehensive skeletal assemblages of a small bodied, early diverging ornithischian described from North America to date. Phylogenetic analysis recovers Fona as the earliest member of Thescelosaurinae, minimally containing Oryctodromeus, and all three species of Thescelosaurus, revealing the clade was well-established in North America by as early as the Cenomanian, and distinct from, yet continental cohabitants with, their sister clade, Orodrominae. To date, orodromines and thescelosaurines have not been found together within a single North American ecosystem, suggesting different habitat preferences or competitive exclusion. Osteological observations reveal extensive intraspecific variation across cranial and postcranial elements, and a number of anatomical similarities with Oryctodromeus, suggesting a shared semi-fossorial lifestyle.

SYSTEMATIC PALEONTOLOGY

DINOSAURIA Owen (1842).

ORNITHISCHIA Seeley (1887).

NEORNITHISCHIA Cooper, 1985 (sensu Butler et al., 2008).

ORNITHOPODA Marsh, 1881 (sensu Butler et al., 2008).

THESCELOSAURIDAE (Sternberg, 1937). 

THESCELOSAURINAE (Sternberg, 1940).

THESCELOSAURINAE indet.

Fona herzogae sp. nov.

  Holotype: NCSM 33548, a single partially articulated, nearly complete skeleton. 

 Occurrence: NCSM 33548 was recovered from the Karmic Orodromine locality (UT-16-07-22-Z1), lower Mussentuchit Member, upper Cedar Mountain Formation, Emery County, Utah, USA (Figure 1). Stratigraphic occurrence is between MAZ1 and Last Chance Sandstone (99.466 + 0.046/−0.053 Ma; Tucker et al., 2023) making it the only locality definitively preserving F. herzogae from the lower Mussentuchit unit to date. Mini Troll (NCPALEOUT16) is the geologically youngest locality, emplaced below MAZ3, with an age of 99.231 + 0.090/−0.052 Ma. FMNH PR 4581 was preserved at the Manolo site (UT130831), (99.411 + 0.056/−0.061 Ma) above MAZ2 in the upper Mussentuchit (Figure 1).

Age data is based on a Bayesian age stratigraphic model (Trayler et al., 2020) of the member originally detailed in Tucker et al. (2023). Materials referable to Fona span the lower to upper Mussentuchit Member of the Cedar Mountain Formation, a range of, at minimum, 235,000 kyr. UT-16-07-22-Z1 and NCPALEOUT16 are located on land administered by the US Bureau of Land Management, respectively; exact locality information is restricted by federal statute and is available to qualified researchers via the NCSM.

  DIAGNOSIS: Fona herzogae is a small-bodied, early diverging ornithischian with the following unique combination of characters (autapomorphies are denoted with an asterisk) (Figure 5) *(1) a rostral maxillary fossa located caudal to the first tooth position (unknown in Oryctodromeus and possibly shared by Isaberrysaura and Haya); *(2) an otoccipital that bears a dorsoventrally elongate fossa on the medial surface of the occipital condyle located directly caudal to the medial opening of CN XII; *(3) a rostrocaudally oriented ventral canal on the prootic; *(4) The dorsal margin of the axis neural spine is parallel with the dorsal suture of the centrum, forming an angle of essentially ~0°. *(5) Ischial shaft has bulbous thickening along the dorsal margin directly distal to the obturator process (prominent on both ischia of at least two individuals and weakly present on only the right of another.) (6) base of the prepubic process bears a prominent lateral swelling (possibly present but significantly reduced in Oryctodromeus and Th. neglectus). (7) the caudoventral prong of the jugal's caudal process underlaps a groove along the ventral margin of the quadratojugal (shared by Th. neglectus, likely Changmiania, and possibly at least one specimen of Jeholosaurus [STMN 23–17]). (8) dentary teeth with vertical wear facets on the labial surface that terminate abruptly near the crown base to form a mesiodistally inclined shelf (shared by Oryctodromeus). (9) A low, round tuberosity on the medial side of the scapula located directly opposite to the glenoid ridge (shared with Oryctodromeus and possibly Iani smithi). Standard skeletal measurements of NCSM 33548 are provided in Table 1. Characters 7–9 serve as important synapomorphies that help place Fona within Thescelosaurinae.

Fona n. gen.

  Etymology: Fona (/Foat'NAH/) from the Austronesian language Finoʼ CHamoru. The ancestral maga'håga of the CHamoru people is Fo'na whose name can be translated as ‘the origin’. With her brother Pontan, whose name can be translated as ‘a ripe coconut’, they became the first paramount female and male chiefs (the ancestral maga'låhi of the CHamoru people), ancestrally venerated according to CHamoru tradition (Borja-Quichocho-Calvo, 2021; Cruz, 2022). According to oral history and legend, when Pontan's spirit began to perish and die, Fo'na discovers her powers and uses them to craft parts of Pontan's body into the pieces of the universe. His eyes were turned into the sun and moon, his eyebrows became the rainbows, his back the earth, his chest the sky, his blood the ocean, and from his stomach and penis the mountains and the sacred Creation Point stone pillar were born (Duhaylonsod & Cepeda, 2022). Fo'na had such sorrow from the loss of her brother that her tears flowed down his body to form the currents of the sea, and in reverence to her brother's dream, she decided to bring life to the universe, throwing herself into the earth where her body turned to stone. From her fossilized body sprang forth the first people at Fuha Rock, imbued with her good spirit (Cepeda, 2021; Cunningham, 1992; Perez, 2019; Perez, 2021). This ancestral story of the CHamoru people mirrors the life and death of the thescelosaurine dinosaurs at the Mini Troll locality, as there were at least two subadult individuals that may have been male and female, or perhaps siblings. Additionally, their bodies fell into the earth where they too fossilized. This naming, rooted in the story of Pontan's sacrifice and Fo'na's love for her brother, highlights the CHamoru values of inafa'måolek (to make good for all), geftåo (the need for compassion, selflessness, and familial bonds) (Duhaylonsod & Cepeda, 2022), the importance of the equality shared between women and men (Naholowa'a, 2018), and ongoing efforts to decolonize paleontology (Monarrez et al., 2021). 

Fona herzogae sp. nov.

  Etymology: The specific epithet honors Lisa Herzog (discoverer of the Mini Troll locality) for her unparalleled dedication to the paleontology program at the NCSM and the collection, care, and conservation of fossil specimens worldwide.

CONCLUSION: 

Fona herzogae adds to the cryptic diversity of the Mussentuchit Member dinosaur fauna, serving as an important component of this exceptional mid-Cretaceous ecosystem. It would have lived alongside the hadrosauromorph Eolambia caroljonesa (McDonald et al., 2017), the Rhabdadontomorph Iani smithi (Zanno, Gates, et al., 2023), the small-bodied tyrannosaur Moros intrepidus (Zanno, Tucker, et al., 2019), the large-bodied allosaurian Siats meekerorum (Zanno & Makovicky, 2013), an unnamed oviraptorosaur (Zanno, Avrahami, et al., 2019) and neoceratopsian (Zanno, Tucker, et al., 2023), and a collection of other terrestrial vertebrates (Avrahami et al., 2018).

The presence of a distinct thescelosaurine taxon in the Mussentuchit member supports the hypothesis that the ancestors of Thescelosaurus were present in North America as early as the Cenomanian, co-inhabiting the continent with their sister-taxon Orodrominae. To date, members of these clades have not been found together, suggesting different habitat preferences. Shared ecomorphology with, and a close phylogenetic affinity with Oryctodromeus demonstrated here, supports a shared semi-fossorial lifestyle. Some of the extensive intraspecific variation among specimens of Fona is likely attributable to ontogenetic transformations, whereas others may suggest a broad phenotypic range for the taxon or may point to sexual dimorphism.

 

Haviv M. Avrahami, Peter J. Makovicky, Ryan T. Tucker, Lindsay E. Zanno. 2024. A New semi-fossorial thescelosaurine Dinosaur from the Cenomanian-age Mussentuchit Member of the Cedar Mountain Formation, Utah. The Anatomical Record

DOI: doi.org/10.1002/ar.25505

https://sciences.ncsu.edu/news/life-underground-suited-new-dinosaur-fine 

[Paleontology • 2024] Comptonatus chasei • A New iguanodontian Dinosaur (Iguanodontia: Hadrosauriformes) from the Lower Cretaceous Wessex Formation of the Isle of Wight, southern England

Comptonatus chasei

Lockwood, Martill & Maidment, 2024

DOI: 10.1080/14772019.2024.2346573

 artwork by John Sibbick.

 

Abstract

A new iguanodontian dinosaur, Comptonatus chasei gen. et sp. nov., is described from the Lower Cretaceous Wessex Formation of the Isle of Wight. These strata provide an important record of a critical time in the development of iguanodontian diversity. The specimen, which is described here for the first time, was found and excavated in 2013 and represents the most complete iguanodontian skeleton discovered in the Wealden Group for a century. A new taxon is diagnosed by several autapomorphies found in the neurocranium, teeth, coracoid and other parts of the body, together with a unique suite of characters. These include a dentary with a straight ventral border, and a markedly expanded prepubic blade. These features set it apart from the sympatric Mantellisaurus atherfieldensis, Brighstoneus simmondsi and Iguanodon cf. bernissartensis, increasing the known diversity of this clade in the Barremian–early Aptian of England.  

Keywords: Barremian, Wealden Group, supraoccipitalvomer, diversity

Systematic palaeontology

Dinosauria Owen, 1842

Ornithischia Seeley, 1887

Ornithopoda Marsh, 1881

Iguanodontia Baur, 1891

Ankylopollexia Sereno, 1986

Styracosterna Sereno, 1986

Hadrosauriformes Sereno, 1997

Comptonatus gen. nov.

Etymology: Comptonatus (‘the Compton thunderer’) is a contraction of the words ‘Compton’ on the Isle of Wight and ‘tonatus’, the Latin for thundered, and reflects the place of discovery and the large size of the animal.

Location and horizon: The Wessex Formation, ‘middle’ Barremian, Lower Cretaceous. IWCMS 2014.80 was excavated during September–October 2013, from a plant debris bed on National Trust property to the west of the fault in Compton Bay, and close (c. 50 m) to where IWCMS 2013.175, a skeleton of Valdosaurus canaliculatus Galton, Citation1977 (Barrett, Citation2016) was excavated the previous year. The excavation was conducted under the supervision of Dinosaur Isle Museum (IWCMS) and site records and drawings were collected by Mr Stephen Hutt, the then curator. The site exposes a deep (c. 3 m) plant debris bed that occasionally yields articulated dinosaur remains, but frequently produces the trunks of large conifers, usually attributed to Pseudofrenelopsis parceramosa (Francis, Citation1987). Other vertebrate remains uncovered from the excavation site include ganoid fish scales (cf. Scheenstia sp.), an indeterminate crocodilian tooth and several very large, but fragmentary iguanodontian remains, including three pedal phalanges, a neural arch, and some rib sections.

 Comptonatus chasei gen. et sp. nov. (IWCMS 2014.80).
Preliminary reconstruction of the skull. Shaded areas represent material present in the holotype.

Abbreviations: d, dentary; f, frontal; m, maxilla; n, nasal; nc, neurocranium; orb, orbit; p, parietal; pa, paroccipital process; pf, prefrontal; po, postorbital; q, quadrate, s, surangular; sq, squamosal. Scale bar represents 100 mm.

 Comptonatus chasei gen. et sp. nov. (IWCMS 2014.80). Life restoration.

Original artwork by John Sibbick.

Comptonatus chasei gen. et sp. nov.

Etymology: The specific name honours the late Mr Nick Chase, winner of the Palaeontological Association’s Mary Anning Award in 2018, who made the initial discovery and through his lifetime contributed enormously to the collections at Dinosaur Isle Museum, Isle of Wight, and the Natural History Museum, London (Lockwood et al., Citation2019).

 

Jeremy A. F. Lockwood, David M. Martill and Susannah C. R. Maidment. 2024. Comptonatus chasei, A New iguanodontian Dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, southern England. Journal of Systematic Palaeontology. 22(1); 2346573. DOI: doi.org/10.1080/14772019.2024.2346573

 www.port.ac.uk/news-events-and-blogs/news/research-reveals-the-most-complete-dinosaur-discovered-in-the-uk-in-a-century