[Paleontology • 2024] Theropod Dinosaur Diversity of the lower English Wealden: Analysis of a tooth-based fauna from the Wadhurst Clay Formation (Lower Cretaceous: Valanginian) via phylogenetic, discriminant and machine learning methods

An Early Cretaceous floodplain in southeastern England, 135 million years ago:
a spinosaur takes over the carcass of an ornithopod, much to the annoyance of the smaller tyrannosaurs (left) and dromaeosaurids.

in Barker, Handford, Naish, Wills, Hendrickx, ... et Gostling, 2024. 

DOI: doi.org/10.1002/spp2.1604

artwork by Anthony Hutchings.

 

Abstract

The Lower Cretaceous Wealden Supergroup of southern England yields a diverse assemblage of theropod dinosaurs, its taxa being represented by fragments in addition to some of the most informative associated skeletons of the European Mesozoic. Spinosaurids, neovenatorid allosauroids, tyrannosauroids and dromaeosaurids are among reported Wealden Supergroup clades. However, the majority of relevant specimens are from the Barremian Upper Weald Clay and Wessex formations, and theropod diversity in the older Berriasian–Valanginian Hastings Group has remained poorly known, the fragmentary specimens reported thus far remaining enigmatic both in terms of phylogenetic affinities and sometimes provenance. A better understanding would be welcome given the paucity of Berriasian–Valanginian dinosaurs worldwide. Here, we describe an assemblage of Hastings Group theropod teeth from the Valanginian Wadhurst Clay Formation, mostly collected from the Ashdown Brickworks locality near Bexhill, East Sussex. These teeth were assessed using phylogenetic, discriminant and machine learning analyses and were found to include members of Spinosauridae, Tyrannosauroidea and Dromaeosauridae, in addition to others that remain of uncertain affinity within Coelurosauria. The taxa appear distinct from those already known from Wealden Supergroup strata: the spinosaurid cannot be referred to Baryonyx or the tyrannosauroid to Eotyrannus, for example, but we have not named new taxa at this time. Combined with other findings in the Wadhurst Clay Formation, our study indicates that Valanginian theropod diversity was comparable to that of younger Wealden Supergroup units, implying that the ‘characteristic’ theropod components of Wealden faunas were established early in the deposition of this famous geological succession.

Keywords: theropod, Wealden Supergroup, phylogenetics, machine learning, dinosaur, Cretaceous

Theropod teeth from the Wadhurst Clay Formation.
A, BEXHM 1995.485 (morphotype I). B, BEXHM 2002.50.123 (morphotype II). C, BEXHM 2002.50.124 (morphotype III). D, BEXHM 2005.29 (morphotype IV). E, NHMUK PV R37630 (morphotype V).

 A, C–E, lingual; B, labial view. Scale bar represents 10 mm.

Schematic representation of the theropod diversity throughout the Wealden Supergroup, with specimens from the Wealden Group (Wessex sub-basin) and the Hastings and Weald Clay groups (Weald sub-basin).

DOI: doi.org/10.1002/spp2.1604

An Early Cretaceous floodplain in southeastern England, 135 million years ago: a spinosaur (centre) takes over the carcass of an ornithopod, much to the annoyance of the smaller tyrannosaurs (left) and dromaeosaurids (bottom right).

artwork by Anthony Hutchings.

Chris T. Barker, Lucy Handford, Darren Naish, Simon Wills, Christophe Hendrickx, Phil Hadland, Dave Brockhurst and Neil J. Gostling. 2024. Theropod Dinosaur Diversity of the lower English Wealden: Analysis of a tooth-based fauna from the Wadhurst Clay Formation (Lower Cretaceous: Valanginian) via phylogenetic, discriminant and machine learning methods. Papers in Palaeontology. DOI: doi.org/10.1002/spp2.1604

[Paleontology • 2024] A Reassessment of the historical Fossil Findings from Bahia State (Northeast Brazil) reveals A diversified Dinosaur Fauna in the Lower Cretaceous of South America

faunal components of the Marfim Formation (Valanginian–Hauterivian), the Recôncavo Basin during Lower Cretaceous

Tietasaura derbyiana

Bandeira, Navarro, Pêgas, Brilhante, Brum, de Souza, da Silva & Gallo, 2024

 

DOI: 10.1080/08912963.2024.2318406  

 Researchgate.net/publication/379778273

ABSTRACT

Supposed dinosaur remains were collected between 1859 and 1906 in the Lower Cretaceous Recôncavo Basin (Northeast Brazil). Since these materials remained undescribed, and most were considered lost. Recently, some of these historical specimens were rediscovered in the Natural History Museum of London, providing an opportunity to revisit them after 160 years. The specimens come from five different sites, corresponding to the Massacará (Berriasian-Barremian) and Ilhas (Valanginian-Barremian) groups. Identified bones comprise mainly isolated vertebral centra from ornithopods, sauropods, and theropods. Appendicular remains include a theropod pedal phalanx, humerus, and distal half of a left femur with elasmarian affinities. Despite their fragmentary nature, these specimens represent the earliest dinosaur bones discovered in South America, enhancing our understanding of the Cretaceous dinosaur faunas in Northeast Brazil. The dinosaur assemblage in the Recôncavo Basin resembles coeval units in Northeast Brazil, such as the Rio do Peixe Basin, where ornithopods coexist with sauropods and theropods. This study confirms the presence of ornithischian dinosaurs in Brazil based on osteological evidence, expanding their biogeographic and temporal range before the continental rifting between South America and Africa. Additionally, these findings reinforce the fossiliferous potential of Cretaceous deposits in Bahia State, which have been underexplored since their initial discoveries.

KEYWORDS: Recôncavo Basin, Massacará Group, Ilhas Group, Ornithischia, Sauropoda, Theropoda

  

  

 Paleontographical reconstruction of the hypothetical paleoenvironment of the Recôncavo Basin during Lower Cretaceous: A, faunal components of the Marfim Formation (Valanginian–Hauterivian); B, faunal components of the Pojuca Formation (Hauterivian–Barremian). The Salvador Formation is partially synchronous with both units, sharing coeval components.

Artwork by Matheus Gadelha.

Dinosauria Owen Citation1842

Ornithischia Seeley Citation1888

Genasauria Sereno Citation1986

Neornithischia Cooper Citation1985

Cerapoda Sereno Citation1986

Ornithopoda Marsh Citation1881

Elasmaria Calvo et al. Citation2007

Tietasaura gen. nov. 

Etymology: The generic epithet is a combination of Tieta (nickname for Antonieta in Portuguese) and -saura (σαύρα), the genitive form of -saurus and meaning lizard in ancient Greek. The name Tieta honours the main character from the homonymous novel ‘Tieta do Agreste’ by the famous author Jorge Amado, who was born in Bahia and lived in Salvador City. The name Antonieta further means ‘priceless’, alluding to the value of Tietasaura derbyiana sp. nov. as the first nominal ornithischian species from Brazil.

 

Tietasaura derbyiana sp. nov.

Etymology: The specific epithet is an eponym honouring Orville A. Derby (1851–1915), founder and the first director from Brazilian Mineralogical and Geological Commission (Serviço Geológico e Mineralógico do Brasil, nowadays SGB), being also the former director of the National Museum of Rio de Janeiro (MN) and one of the pioneers of palaeontology in the Recôncavo Basin. Despite all tragedies in his life and the blatant lack of governmental support, Derby valiantly fought for the scientific progress of the Brazilian geosciences.

Holotype: NHM-PV R.3424, represented by a distal half of a small left femur.

Diagnosis: Small sized elasmarian ornithopod exhibiting an unique combination of character states on the femur (putative autapomorphies marked with an asterisk): presence of a marked anterior linea muscularis followed by several longitudinal striae converging distally towards the intercondylar extensor groove; broad but shallow intercondylar extensor groove; stout supracondylar ridges that extends medially; fibular supracondylar ridge sinuous and bearing a lateral fossa*; hemispherical distal femoral condyles in the posterior view, being the tibial condyle twice as large as fibular condyle; distinct prominent crest in the median margin of the tibial condyle*; fibular condyle with straight lateral margin and continuous in the distal view, lacking an indentation formed by a condyloid (rectangular) process; presence of an offset condylid, medial to the fibular condyle; broad and deep intercondylar flexor fossa, subtriangular in shape and much extending into the diaphysis.

Type locality and horizon: The holotype of Tietasaura derbyiana was recovered at a beach near the Plataforma Station (Locality 3), Salvador City, Bahia State. The shale facies outcropping in this locality are associated with the Valanginian – Hauterivian Marfim Formation (Ilhas Group, Recôncavo Basin).

...

 

Kamila L. N. Bandeira, Bruno A. Navarro, Rodrigo V. Pêgas, Natan S. Brilhante, Arthur S. Brum, Lucy G. de Souza, Rafael C. da Silva and Valéria Gallo. 2024. A Reassessment of the historical Fossil Findings from Bahia State (Northeast Brazil) reveals A diversified Dinosaur Fauna in the Lower Cretaceous of South America. Historical Biology: An International Journal of Paleobiology. DOI: 10.1080/08912963.2024.2318406    Researchgate.net/publication/379778273_fossil_findings_from_Bahia_NE_Brazil

[Paleontology • 2024] Diving Dinosaurs? Caveats on the Use of Bone Compactness and pFDA for inferring Lifestyle

 Spinosaurus aegyptiacus

in Myhrvold, Baumgart, Vidal, Fish, Henderson, Saitta et Sereno, 2024. 

DOI: 10.1371/journal.pone.0298957 

 twitter.com/Stephanopteryx

Reconstruction by Dani Navarro

Abstract

The lifestyle of spinosaurid dinosaurs has been a topic of lively debate ever since the unveiling of important new skeletal parts for Spinosaurus aegyptiacus in 2014 and 2020. Disparate lifestyles for this taxon have been proposed in the literature; some have argued that it was semiaquatic to varying degrees, hunting fish from the margins of water bodies, or perhaps while wading or swimming on the surface; others suggest that it was a fully aquatic underwater pursuit predator. The various proposals are based on equally disparate lines of evidence. A recent study by Fabbri and coworkers [2022] sought to resolve this matter by applying the statistical method of phylogenetic flexible discriminant analysis to femur and rib bone diameters and a bone microanatomy metric called global bone compactness. From their statistical analyses of datasets based on a wide range of extant and extinct taxa, they concluded that two spinosaurid dinosaurs (S. aegyptiacus, Baryonyx walkeri) were fully submerged “subaqueous foragers,” whereas a third spinosaurid (Suchomimus tenerensis) remained a terrestrial predator. We performed a thorough reexamination of the datasets, analyses, and methodological assumptions on which those conclusions were based, which reveals substantial problems in each of these areas. In the datasets of exemplar taxa, we found unsupported categorization of taxon lifestyle, inconsistent inclusion and exclusion of taxa, and inappropriate choice of taxa and independent variables. We also explored the effects of uncontrolled sources of variation in estimates of bone compactness that arise from biological factors and measurement error. We found that the ability to draw quantitative conclusions is limited when taxa are represented by single data points with potentially large intrinsic variability. The results of our analysis of the statistical method show that it has low accuracy when applied to these datasets and that the data distributions do not meet fundamental assumptions of the method. These findings not only invalidate the conclusions of the particular analysis of Fabbri et al. but also have important implications for future quantitative uses of bone compactness and discriminant analysis in paleontology.

 

  

Nathan P. Myhrvold, Stephanie L. Baumgart, Daniel Vidal, Frank E. Fish, Donald M. Henderson, Evan T. Saitta and Paul C. Sereno. 2024. Diving Dinosaurs? Caveats on the Use of Bone Compactness and pFDA for inferring Lifestyle. PLoS ONE. 19(3): e0298957. DOI: 10.1371/journal.pone.0298957

  twitter.com/Stephanopteryx/status/1765472382289080658 

[Paleontology • 2024] Riojavenatrix lacustris • Increasing the Theropod Record of Europe: A New basal spinosaurid (Theropoda: Spinosauridae) from the Enciso Group of the Cameros Basin (La Rioja, Spain). Evolutionary Implications and Palaeobiodiversity

Riojavenatrix lacustris 

 Isasmendi, Cuesta, Díaz-Martínez, Company, Sáez-Benito, Viera, Torices & Pereda-Suberbiola, 2024

DOI: 10.1093/zoolinnean/zlad193 

Reconstruction by Adrián Blázquez Riola  twitter.com/AdriSuchoBlaink

Abstract

A new member of Spinosauridae from the Enciso Group (uppermost Barremian–lower Aptian) from Igea (La Rioja, Spain) is here erected on the basis of axial, pelvic girdle, and hindlimb elements that exhibit a unique combination of characters. Riojavenatrix lacustris gen. et sp. nov. is one of the latest Iberian and European spinosaurid taxa. It retains a triangular pubic boot, like the megalosaurids, and a medial condyle of the femur that shows a transitional stage between the anteroposteriorly oriented long axis of non-spinosaurid theropods and the posteromedially oriented long axis of Spinosauridae. The spinosaurid record of Iberia ranges from the late Hauterivian–early Barremian to the latest Barremian–early Aptian so far, and both the oldest and the most recent evidence comes from the Cameros Basin, where spinosaurid remains are especially abundant in the Barremian deposits. A review of the spinosaurid record has allowed us to dismiss the presence of the genus Baryonyx from Iberia; hence, only Camarillasaurus, Iberospinus, Protathlitis, Riojavenatrix gen. nov., and Vallibonavenatrix are considered to be present in the Early Cretaceous of Iberia. According to this study, Riojavenatrix is one of the youngest baryonychines in the fossil record.

Baryonychinae, dinosaur, Early Cretaceous, Europe, Iberian Peninsula, Megalosauroidea, Spinosauridae, Theropoda

 

Riojavenatrix lacustris gen. et sp. nov

Erik Isasmendi, Elena Cuesta, Ignacio Díaz-Martínez, Julio Company, Patxi Sáez-Benito, Luis I Viera, Angelica Torices and Xabier Pereda-Suberbiola. 2024. Increasing the Theropod Record of Europe: A New basal spinosaurid from the Enciso Group of the Cameros Basin (La Rioja, Spain). Evolutionary Implications and Palaeobiodiversity. Zoological Journal of the Linnean Society., zlad193. DOI: 10.1093/zoolinnean/zlad193

   twitter.com/AdriSuchoBlaink/status/1759482297198211552

  

 

[Paleontology • 2023] Protathlitis cinctorrensis • A New spinosaurid Dinosaur Species (Theropoda: Spinosauridae) from the Early Cretaceous of Cinctorres, Spain

 

Protathlitis cinctorrensis

Santos-Cubedo, Santisteban, Poza & Meseguer, 2023

DOI: 10.1038/s41598-023-33418-2

Abstract

A new spinosaurid genus and species is described based on the right maxilla and five caudal vertebrae of a single specimen from the Arcillas de Morella Formation (Early Cretaceous) at the locality of Cinctorres (Castellón, Spain). Protathlitis cinctorrensis gen. et sp. nov. is diagnosed by one autapomorphic feature as well as by a unique combination of characters. The autapomorphy includes a subcircular depression in the anterior corner of the antorbital fossa in the maxilla. The new Iberian species is recovered as a basal baryonychine. The recognition of Protathlitis cinctorrensis gen. et sp. nov. as the first baryonychine dinosaur species identified from the Arcillas de Morella Formation (late Barremian) from the same time as Vallibonavenatrix cani, the first spinosaurine dinosaur from the same formation in the Morella subbasin (Maestrat Basin, eastern Spain), indicates that the Iberian Peninsula was home to a highly diverse assemblage of medium-to-large bodied spinosaurid dinosaurs. It seems that spinosaurids appeared during the Early Cretaceous in Laurasia, with the two subfamilies occupying the western part of Europe during this period. Later, during the Barremian–Aptian, they migrated to Africa and Asia, where they would diversify. In Europe, baryonychines were dominant, while in Africa, spinosaurines were most abundant.

 

Protathlitis cinctorrensis gen. et sp. nov.

 

Andrés Santos-Cubedo, Carlos de Santisteban, Begoña Poza and Sergi Meseguer. 2023. A New spinosaurid Dinosaur Species from the Early Cretaceous of Cinctorres (Spain). Scientific Reports. 13: 6471. DOI: 10.1038/s41598-023-33418-2

[Paleontology • 2023] A Reappraisal of the Cranial and Mandibular Osteology of the spinosaurid Irritator challengeri (Dinosauria: Theropoda)

Irritator challengeri  Martill, Cruickshank, Frey, Small & Clarke, 1996

in Schade, Rauhut, Foth, Moleman et Evers, 2023. 

DOI: 10.26879/1242

 twitter.com/LordTrilobite

ABSTRACT

Although originally described almost three decades ago, the holotype of Irritator challengeri from the Lower Cretaceous Romualdo Formation of Brazil still represents the most complete spinosaurid skull known to science. Here, we present a detailed description of the skull of Irritator based on digital reconstructions from medical and micro computed tomography (µCT) data. Segmentation reveals the near-complete palatal complex and braincase, an unusual morphology of the retroarticular process, a large, ventrally inclined surangular shelf and the tooth replacement pattern. The digitally reconstructed skull anatomy indicates a robust dentition, a field of binocular vision in front of the skull with an inclined snout orientation, a relatively weak but fast bite, as well as laterally spreading and rotating lower jaw rami during jaw opening. We modified an existing phylogenetic matrix of Tetanurae to account for new observations on the morphology of Irritator and analysed this using parsimony and Bayesian methods. Results support Spinosauridae as members of Megalosauroidea and recover a monophyletic Carnosauria (Megalosauroidea + Allosauroidea). Parsimony analysis recovers Monolophosaurus nested within Megalosauroidea as sister taxon to spinosaurids, but this is not supported by the Bayesian analysis. Bayesian time-calibration and evolutionary rate analysis indicate that spinosaurid evolution happened fast, despite a long ghost lineage of at least 35 million years. High evolutionary rates over a prolonged time can explain the highly derived skull morphology of spinosaurids. This study provides an in-depth look into the evolution of spinosaurid skull anatomy and refines our understanding of these specialized Mesozoic predators.

Keywords: Dinosaur; Theropod; Spinosaurid; Cretaceous; Mesozoic; Brazil

Theropoda Marsh, 1881

Tetanurae Gauthier, 1986

Megalosauroidea Fitzinger, 1843; sensu Carrano et al. (2012)

Spinosauridae Stromer, 1915

Spinosaurinae (Stromer, 1915); sensu Sereno et al. (1998)

Irritator challengeri Martill, Cruickshank, Frey, Small and Clarke, 1996

Holotype. SMNS 58022, largely complete skull, missing most of the premaxillae, anterior ends of the maxillae, and anteriormost parts of both mandibles.

Locality and horizon. Near Buxexé, close to Santana do Cariri, Ceará State, northeastern Brazil (see Sues et al., 2002: 535). Lower part of the Romualdo Formation (Santana Formation of some authors; see discussion in Arai and Assine, 2020) of the Santana Group, late Aptian (Arai and Assine, 2020).

Marco Schade, Oliver W. M. Rauhut, Christian Foth, Olof Moleman, and Serjoscha W. Evers. 2023. A Reappraisal of the Cranial and Mandibular Osteology of the spinosaurid Irritator challengeri (Dinosauria: Theropoda). Palaeontologia Electronica. 26(2): a17.DOI: 10.26879/1242

 

palaeo-electronica.org/content/2023/3821-the-osteology-of-irritator

 twitter.com/LordTrilobite/status/1656583542720086016

[Paleontology • 2023] Modified Skulls but Conservative Brains? The Palaeoneurology and Endocranial Anatomy of baryonychine Dinosaurs (Theropoda: Spinosauridae)

Ceratosuchops inferodios and the orientation of the endocast in the skull.

in Barker, Naish, Trend, Michels, ... et Gostling, 2023. 

DOI: 10.1111/joa.13837

 twitter.com/WitmerLab

  twitter.com/Vectivenator 

Illustration: Anthony Hutchings

Abstract

The digital reconstruction of neurocranial endocasts has elucidated the gross brain structure and potential ecological attributes of many fossil taxa, including Irritator, a spinosaurine spinosaurid from the “mid” Cretaceous (Aptian) of Brazil. With unexceptional hearing capabilities, this taxon was inferred to integrate rapid and controlled pitch-down movements of the head that perhaps aided in the predation of small and agile prey such as fish. However, the neuroanatomy of baryonychine spinosaurids remains to be described, and potentially informs on the condition of early spinosaurids. Using micro-computed tomographic scanning (μCT), we reconstruct the braincase endocasts of Baryonyx walkeri and Ceratosuchops inferodios from the Wealden Supergroup (Lower Cretaceous) of England. We show that the gross endocranial morphology is similar to other non-maniraptoriform theropods, and corroborates previous observations of overall endocranial conservatism amongst more basal theropods. Several differences of unknown taxonomic utility are noted between the pair. Baryonychine neurosensory capabilities include low-frequency hearing and unexceptional olfaction, whilst the differing morphology of the floccular lobe tentatively suggests less developed gaze stabilisation mechanisms relative to spinosaurines. Given the morphological similarities observed with other basal tetanurans, baryonychines likely possessed comparable behavioural sophistication, suggesting that the transition from terrestrial hypercarnivorous ancestors to semi-aquatic “generalists” during the evolution of Spinosauridae did not require substantial modification of the brain and sensory systems.

Artist's impression of Ceratosuchops inferodios and the orientation of the endocast in the skull.

Illustration: Anthony Hutchings

 

Chris Tijani Barker, Darren Naish, Jacob Trend, Lysanne Veerle Michels, Lawrence Witmer, Ryan Ridgley, Katy Rankin, Claire E. Clarkin, Philipp Schneider and Neil J. Gostling. 2023. Modified Skulls but Conservative Brains? The Palaeoneurology and Endocranial Anatomy of baryonychine Dinosaurs (Theropoda: Spinosauridae). Journal of Anatomy. DOI: 10.1111/joa.13837

 twitter.com/WitmerLab/status/1625566752599076866

www.southampton.ac.uk/news/2023/02/oldest-spinosaur-brains-revealed.page

  twitter.com/Vectivenator/status/1625298780420739073

  twitter.com/TetZoo/status/1625299630664589313

[Paleontology • 2023] The Vertebrate Fossil Record from the Feliz Deserto Formation (Lower Cretaceous), Sergipe, NE Brazil: Paleoecological, Taphonomic, and Paleobiogeographic Implications

in Lacerda, de Andrade, Sales, Aragão, ... et Liparini, 2023. 

DOI: 10.1016/j.cretres.2022.105463

 Highlights: 

• Increase of knowledge about Lower Cretaceous archosaurs from Brazil.

• First crocodyliform fossil findings of the Feliz Deserto Formation.

• Additional records of the oldest Gondwanan spinosaurine theropods.

• Paleoenvironmental characterization of Canafístula 01 fossiliferous locality.

Abstract

The Feliz Deserto Formation (Berriasian–Valanginian, Sergipe-Alagoas Basin, NE Brazil) preserved some of the earliest South American fossil records of the rifting stages which resulted in the Gondwana supercontinent break-up during the Lower Cretaceous. Recently, the first spinosaurid theropod record of this formation was described, based on a tooth recovered from Canafístula 01 fossil locality in Sergipe State. We add herein twenty-seven isolated specimens to the fossil record of the Lower Cretaceous Feliz Deserto Formation. The new material includes seven isolated spinosaurid theropod teeth of the spinosaurine clade, as well as an indeterminate theropod preungual pedal phalanx. In addition, we describe an isolated crocodyliform osteoderm, as well as eighteen isolated teeth, some of which were taxonomically identified in three distinct morphotypes of neosuchian crocodyliforms. These findings expand the Gondwanan fossil record of both spinosaurine theropods and neosuchian crocodyliforms. Despite the fragmented nature of the specimens, these new fossils allowed the characterization of their general taphonomic features with low fluvial transport of bioclast prior to the burial. The depositional paleoenvironment of the Canafístula 01 locality is compatible with the deltaic system unit, that characterizes part of the Feliz Deserto Formation during the Lower Cretaceous. These fossil findings exemplify the co-occurrence of spinosaurids and more than one taxon of crocodyliforms in the deltaic-lacustrine paleoenvironment represented by the Feliz Deserto Formation. These new occurrences reinforce the fossiliferous potential of the Canafístula 01 locality, especially related to the paleovertebrates from the Lower Cretaceous of Brazil.

 

Keywords: Berriasian–Valanginian, Mesoeucrocodylia, Paleovertebrates, Sergipe-Alagoas Basin, Spinosauridae, Theropoda

Mauro B.S. Lacerda, Marco B. de Andrade, Marcos A.F. Sales, Paulo R.L. Aragão, Fabiana S. Vieira, Jonathas S. Bittencourt and Alexandre Liparini. 2023. The Vertebrate Fossil Record from the Feliz Deserto Formation (Lower Cretaceous), Sergipe, NE Brazil: Paleoecological, Taphonomic, and Paleobiogeographic Implications. Cretaceous Research. In Press. DOI: 10.1016/j.cretres.2022.105463

[Paleontology • 2022] Plesiosaurs from the Fluvial Kem Kem Group (mid-Cretaceous) of eastern Morocco and A Review of Non-marine Plesiosaurs

in Bunker, Martill, ... et Longrich, 2022. 

 DOI: 10.1016/j.cretres.2022.105310 

Abstract

Plesiosaurs were a long-lived and widespread group of marine reptiles, with a worldwide distribution and a temporal range from the Late Triassic to the Late Cretaceous. Most occur in marine deposits, but some occur in low-salinity, brackish to freshwater environments. We report plesiosaurs from the freshwater fluvial deposits of the mid-Cretaceous (?Albian-Cenomanian) Kem Kem Group of Morocco. Remains include numerous shed teeth, vertebrae, and a humerus. The humerus represents a young juvenile; vertebrae likely belong to sub-adults. Teeth show heavy wear, similar to teeth of co-occurring spinosaurids. While coeval plesiosaurs from the Bahariya Formation of Egypt are members of Polycotylidae, the Kem Kem fossils show features of Leptocleididae, small-bodied plesiosaurs that were widely distributed in nearshore and non-marine settings in the Early Cretaceous. These fossils are the first freshwater plesiosaurs from Morocco, and are among the youngest representatives of Leptocleididae. The Kem Kem leptocleidids could have been infrequent visitors from the sea, freshwater-tolerant, or even freshwater-adapted, as in modern river dolphins. The abundance of shed teeth in the Kem Kem Group supports the hypothesis that they had some degree of freshwater tolerance. Furthermore, leptocleidids occur almost exclusively in shallow nearshore, brackish, or freshwater environments, suggesting adaptation to shallow, low-salinity environments. Other plesiosaur groups and other Mesozoic marine reptiles, including teleosaurids and mosasaurids, also occur in freshwater settings, suggesting plesiosaurs and other marine reptiles frequently exploited non-marine environments.

Keywords: Plesiosauria, Leptocleididae, Palaeoecology, Kem Kem Group, Morocco, Freshwater

Plesiosaurs and spinosaurus may have both inhabited freshwater rivers.

 

Georgina Bunker, David M. Martill, Roy Smith, Samir Zourhi and Nick Longrich. 2022. Plesiosaurs from the Fluvial Kem Kem Group (mid-Cretaceous) of eastern Morocco and A Review of Non-marine Plesiosaurs.   Cretaceous Research. 105310. In Press. DOI: 10.1016/j.cretres.2022.105310 

bath.ac.uk/announcements/plesiosaur-fossils-found-in-the-sahara-suggest-they-werent-just-marine-animals

[Paleontology • 2022] A European Giant: A Large Spinosaurid (Dinosauria: Theropoda) from the Vectis Formation (Wealden Group, Early Cretaceous), UK

in Barker​, Lockwood, Naish, ... et Gostling, 2022.  

DOI: 10.7717/peerj.13543

Abstract 

Postcranial elements (cervical, sacral and caudal vertebrae, as well as ilium, rib and limb bone fragments) belonging to a gigantic tetanuran theropod were recovered from the basal unit (the White Rock Sandstone equivalent) of the Vectis Formation near Compton Chine, on the southwest coast of the Isle of Wight. These remains appear to pertain to the same individual, with enormous dimensions similar to those of the Spinosaurus holotype and exceeding those of the largest European theropods previously reported. A combination of features—including the presence of spinodiapophyseal webbing on an anterior caudal vertebra—suggest that this is a member of Spinosauridae, though a lack of convincing autapomorphies precludes the identification of a new taxon. Phylogenetic analysis supports spinosaurid affinities but we were unable to determine a more precise position within the clade weak support for a position within Spinosaurinae or an early-diverging position within Spinosauridae were found in some data runs. Bioerosion in the form of curved tubes is evident on several pieces, potentially related to harvesting behaviour by coleopteran bioeroders. This is the first spinosaurid reported from the Vectis Formation and the youngest British material referred to the clade. This Vectis Formation spinosaurid is unusual in that the majority of dinosaurs from the Lower Cretaceous units of the Wealden Supergroup are from the fluviolacustrine deposits of the underlying Barremian Wessex Formation. In contrast, the lagoonal facies of the upper Barremian–lower Aptian Vectis Formation only rarely yield dinosaur material. Our conclusions are in keeping with previous studies that emphasise western Europe as a pivotal region within spinosaurid origination and diversification.

Chris T. Barker​, Jeremy A.F. Lockwood, Darren Naish, Sophie Brown, Amy Hart, Ethan Tulloch and Neil J. Gostling. 2022.  A European Giant: A Large Spinosaurid (Dinosauria: Theropoda) from the Vectis Formation (Wealden Group, Early Cretaceous), UK. PeerJ. 10:e13543. DOI: 10.7717/peerj.13543

[Paleontology • 2022] Subaqueous Foraging among Carnivorous Dinosaurs

in Fabbri, Navalón, Benson, Pol, ... et Ibrahim, 2022. 

  

  DOI: 10.1038/s41586-022-04528-0 

  facebook.com/CristianoDalSasso

 twitter.com/tetaneuron

Artwork: Davide Bonadonna 

Abstract

Secondary aquatic adaptations evolved independently more than 30 times from terrestrial vertebrate ancestors. For decades, non-avian dinosaurs were believed to be an exception to this pattern. Only a few species have been hypothesized to be partly or predominantly aquatic. However, these hypotheses remain controversial, largely owing to the difficulty of identifying unambiguous anatomical adaptations for aquatic habits in extinct animals. Here we demonstrate that the relationship between bone density and aquatic ecologies across extant amniotes provides a reliable inference of aquatic habits in extinct species. We use this approach to evaluate the distribution of aquatic adaptations among non-avian dinosaurs. We find strong support for aquatic habits in spinosaurids, associated with a marked increase in bone density, which precedes the evolution of more conspicuous anatomical modifications, a pattern also observed in other aquatic reptiles and mammals. Spinosaurids are revealed to be aquatic specialists with surprising ecological disparity, including subaqueous foraging behaviour in Spinosaurus and Baryonyx, and non-diving habits in Suchomimus. Adaptation to aquatic environments appeared in spinosaurids during the Early Cretaceous, following their divergence from other tetanuran theropods during the Early Jurassic.

Matteo Fabbri, Guillermo Navalón, Roger B. J. Benson, Diego Pol, Jingmai O’Connor, Bhart-Anjan S. Bhullar, Gregory M. Erickson, Mark A. Norell, Andrew Orkney, Matthew C. Lamanna, Samir Zouhri, Justine Becker, Amanda Emke, Cristiano Dal Sasso, Gabriele Bindellini, Simone Maganuco, Marco Auditore and Nizar Ibrahim. 2022. Subaqueous Foraging among Carnivorous Dinosaurs. Nature.  DOI: 10.1038/s41586-022-04528-0

   facebook.com/CristianoDalSasso/posts/10228402473396555

 twitter.com/tetaneuron/status/1506662445196136455