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Mainwaring MC, Medina I, Tobalske BW, Hartley IR, Varricchio DJ, Hauber ME. The evolution of nest site use and nest architecture in modern birds and their ancestors. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220143. [PMID: 37427466 PMCID: PMC10331912 DOI: 10.1098/rstb.2022.0143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 05/19/2023] [Indexed: 07/11/2023] Open
Abstract
The evolution of nest site use and nest architecture in the non-avian ancestors of birds remains poorly understood because nest structures do not preserve well as fossils. Nevertheless, the evidence suggests that the earliest dinosaurs probably buried eggs below ground and covered them with soil so that heat from the substrate fuelled embryo development, while some later dinosaurs laid partially exposed clutches where adults incubated them and protected them from predators and parasites. The nests of euornithine birds-the precursors to modern birds-were probably partially open and the neornithine birds-or modern birds-were probably the first to build fully exposed nests. The shift towards smaller, open cup nests has been accompanied by shifts in reproductive traits, with female birds having one functioning ovary in contrast to the two ovaries of crocodilians and many non-avian dinosaurs. The evolutionary trend among extant birds and their ancestors has been toward the evolution of greater cognitive abilities to construct in a wider diversity of sites and providing more care for significantly fewer, increasingly altricial, offspring. The highly derived passerines reflect this pattern with many species building small, architecturally complex nests in open sites and investing significant care into altricial young. This article is part of the theme issue 'The evolutionary ecology of nests: a cross-taxon approach'.
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Affiliation(s)
| | - Iliana Medina
- School of BioSciences, University of Melbourne, Melbourne VIC 3010, Australia
| | - Bret W. Tobalske
- Field Research Station at Fort Missoula, Division of Biological Sciences, University of Montana, MT 59802, USA
| | - Ian R. Hartley
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - David J. Varricchio
- Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA
| | - Mark E. Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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2
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Lacerda MBS, Bittencourt JS, Hutchinson JR. Macroevolutionary patterns in the pelvis, stylopodium and zeugopodium of megalosauroid theropod dinosaurs and their importance for locomotor function. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230481. [PMID: 37593714 PMCID: PMC10427828 DOI: 10.1098/rsos.230481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 07/27/2023] [Indexed: 08/19/2023]
Abstract
During the Mesozoic, non-avian theropods represented one of the most successful clades globally distributed, with a wide diversity of forms. An example is the clade Megalosauroidea, which included medium- to large-bodied forms. Here, we analyse the macroevolution of the locomotor system in early Theropoda, emphasizing the Megalosauroidea. We scored the Spinosaurus neotype in a published taxon-character matrix and described the associated modifications in character states, mapping them onto a phylogeny and using these to study disparity. In the evolution of Megalosauroidea, there was the mosaic emergence of a low swollen ridge; enlargement of the posterior brevis fossa and emergence of a posterodorsal process on the ilium in some megalosauroids; emergence of a femoral head oriented anteromedially and medially angled, and appearance of posterolaterally oriented medial femoral condyles in spinosaurids. The greatest morphological disparity is in the ilium of megalosaurids; the ischium seems to have a high degree of homoplasy; there is a clear distinction in the femoral morphospace regarding megalosauroids and other theropods; piatnitzkysaurids show considerable disparity of zeugopodial characters. These reconstructions of osteological evolution form a stronger basis on which other studies could build, such as mapping of pelvic/appendicular musculature and/or correlating skeletal traits with changes in locomotor function.
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Affiliation(s)
- Mauro B. S. Lacerda
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield AL9 7TA, UK
- Pós-Graduação em Zoologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil
| | - Jonathas S. Bittencourt
- Departamento de Geologia, Instituto de Geociências, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - John R. Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield AL9 7TA, UK
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3
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Barker CT, Naish D, Gostling NJ. Isolated tooth reveals hidden spinosaurid dinosaur diversity in the British Wealden Supergroup (Lower Cretaceous). PeerJ 2023; 11:e15453. [PMID: 37273543 PMCID: PMC10239232 DOI: 10.7717/peerj.15453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/03/2023] [Indexed: 06/06/2023] Open
Abstract
Isolated spinosaurid teeth are relatively well represented in the Lower Cretaceous Wealden Supergroup of southern England, UK. Until recently it was assumed that these teeth were referable to Baryonyx, the type species (B. walkeri) and specimen of which is from the Barremian Upper Weald Clay Formation of Surrey. British spinosaurid teeth are known from formations that span much of the c. 25 Ma depositional history of the Wealden Supergroup, and recent works suggest that British spinosaurids were more taxonomically diverse than previously thought. On the basis of both arguments, it is appropriate to doubt the hypothesis that isolated teeth from outside the Upper Weald Clay Formation are referable to Baryonyx. Here, we use phylogenetic, discriminant and cluster analyses to test whether an isolated spinosaurid tooth (HASMG G369a, consisting of a crown and part of the root) from a non-Weald Clay Formation unit can be referred to Baryonyx. HASMG G369a was recovered from an uncertain Lower Cretaceous locality in East Sussex but is probably from a Valanginian exposure of the Hastings Group and among the oldest spinosaurid material known from the UK. Spinosaurid affinities are both quantitatively and qualitatively supported, and HASMG G369a does not associate with Baryonyx in any analysis. This supports recent reinterpretations of the diversity of spinosaurid in the Early Cretaceous of Britain, which appears to have been populated by multiple spinosaurid lineages in a manner comparable to coeval Iberian deposits. This work also reviews the British and global records of early spinosaurids (known mainly from dental specimens), and revisits evidence for post-Cenomanian spinosaurid persistence.
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Affiliation(s)
- Chris T. Barker
- Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, United Kingdom
| | - Darren Naish
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Neil J. Gostling
- Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, Southampton, United Kingdom
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4
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Santos-Cubedo A, de Santisteban C, Poza B, Meseguer S. A new spinosaurid dinosaur species from the Early Cretaceous of Cinctorres (Spain). Sci Rep 2023; 13:6471. [PMID: 37202441 DOI: 10.1038/s41598-023-33418-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 04/12/2023] [Indexed: 05/20/2023] Open
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.
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Affiliation(s)
- Andrés Santos-Cubedo
- Àrea de Cristal·lografia i Mineralogia, Departament de Biologia, Bioquímica i Ciències Naturals, Universitat Jaume I, 12071, Castelló, Spain.
- Grup Guix, 12540, Vila-real, Spain.
| | - Carlos de Santisteban
- Departament de Botànica i Geologia, Universitat de València, 46100, Burjassot, Spain
| | | | - Sergi Meseguer
- Àrea de Cristal·lografia i Mineralogia, Departament de Biologia, Bioquímica i Ciències Naturals, Universitat Jaume I, 12071, Castelló, Spain
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5
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Lacerda MBS, Aragão PRL, Vieira FS, Sales MAF, Liparini A. On the first Baryonychinae (Theropoda, Spinosauridae) teeth from South America. Zootaxa 2023; 5264:526-544. [PMID: 37518033 DOI: 10.11646/zootaxa.5264.4.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Indexed: 08/01/2023]
Abstract
We report the first occurrence in South America of spinosaurid specimens belonging to the clade Baryonychinae. The material comprises three tooth crowns recovered from the Lower Cretaceous (Berriasian-Valanginian) of the Feliz Deserto Formation, State of Sergipe, northeast Brazil. The three specimens have the typical conidont condition, displaying a fluted morphology, veined enamel texture and carinae extending to the cervix region, conditions similar to those shared among spinosaurid theropods. Furthermore, a notable feature is the presence of a serrated carinae composed of 6-7 diminutive denticles per millimetre, a key feature shared by baryonychine spinosaurids. Phylogenetic and multivariate analyses performed on dentition-based and crown-based datasets of theropod taxa confirm the relationship of the three tooth crowns described here with the well-supported spinosaurid clade. Our results retrieve the taxa which comprise the "classically" baryonychine clade as individual branches within a polytomy which includes the three tooth crowns and a subclade of spinosaurines (Spinosaurus + Angaturama/Irritator). Additionally, the discriminant and cluster analyses suggest that the materials are more similar to Suchomimus than to Baryonyx morphometrically, but clearly bearing similarities with baryonychines (sharing a similar morphospace). These new findings paleogeographically expand the occurrence of this clade to western Gondwana, and comprise one of the oldest spinosaurid records worldwide, which brings implications on hypotheses for the emergence and evolution of the clade. Furthermore, these new records indicate the presence of more than one spinosaurid taxon in the Lower Cretaceous deltaic paleoenvironment of the Feliz Deserto Formation.
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Affiliation(s)
- Mauro B S Lacerda
- Pós-Graduação em Zoologia; Instituto de Ciências Biológicas; Universidade Federal de Minas Gerais; Belo Horizonte; Minas Gerais 31270-901; Brazil..
| | - Paulo R L Aragão
- Departamento de Biologia; Centro de Ciências Biológicas e da Saúde; Universidade Federal de Sergipe; São Cristóvão; Sergipe 49100-000; Brazil..
| | - Fabiana S Vieira
- Departamento de Biologia; Centro de Ciências Biológicas e da Saúde; Universidade Federal de Sergipe; São Cristóvão; Sergipe 49100-000; Brazil..
| | - Marcos A F Sales
- Campus Acopiara; Instituto Federal de Educação; Ciência e Tecnologia do Ceará; Acopiara; Ceará 63560-000; Brazil..
| | - Alexandre Liparini
- Departamento de Geologia; Instituto de Geociências; Universidade Federal de Minas Gerais; Belo Horizonte; Minas Gerais 31270- 901; Brazil..
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6
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Barker CT, Naish D, Trend J, Michels LV, Witmer L, Ridgley R, Rankin K, Clarkin CE, Schneider P, Gostling NJ. Modified skulls but conservative brains? The palaeoneurology and endocranial anatomy of baryonychine dinosaurs (Theropoda: Spinosauridae). J Anat 2023; 242:1124-1145. [PMID: 36781174 PMCID: PMC10184548 DOI: 10.1111/joa.13837] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/17/2023] [Accepted: 01/17/2023] [Indexed: 02/15/2023] Open
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.
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Affiliation(s)
- Chris Tijani Barker
- Institute for Life Sciences, University of Southampton, University Road, Southampton, UK.,Faculty of Engineering and Physical Sciences, University of Southampton, University Road, Southampton, UK
| | - Darren Naish
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK
| | - Jacob Trend
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK
| | - Lysanne Veerle Michels
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK
| | - Lawrence Witmer
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio Center for Ecology and Evolutionary Studies, Ohio University, Athens, Ohio, USA
| | - Ryan Ridgley
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio Center for Ecology and Evolutionary Studies, Ohio University, Athens, Ohio, USA
| | - Katy Rankin
- μ-VIS X-ray Imaging Centre, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
| | - Claire E Clarkin
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK
| | - Philipp Schneider
- Bioengineering Science Research Group, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK.,High-Performance Vision Systems, Center for Vision, Automation and Control, AIT Austrian Institute of Technology, Vienna, Austria
| | - Neil J Gostling
- Institute for Life Sciences, University of Southampton, University Road, Southampton, UK.,School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, UK
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7
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Barker CT, Lockwood JA, Naish D, Brown S, Hart A, Tulloch E, Gostling NJ. A European giant: a large spinosaurid (Dinosauria: Theropoda) from the Vectis Formation (Wealden Group, Early Cretaceous), UK. PeerJ 2022; 10:e13543. [PMID: 35702254 PMCID: PMC9188774 DOI: 10.7717/peerj.13543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 05/15/2022] [Indexed: 01/17/2023] Open
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.
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Affiliation(s)
- Chris T. Barker
- Institute for Life Sciences, University of Southampton, Southampton, United Kingdom,Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, United Kingdom
| | - Jeremy A.F. Lockwood
- School of Environment, Geography and Geosciences, University of Portsmouth, Portsmouth, United Kingdom,Department of Earth Sciences, Natural History Museum, London, United Kingdom
| | - Darren Naish
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Sophie Brown
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Amy Hart
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Ethan Tulloch
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Neil J. Gostling
- Institute for Life Sciences, University of Southampton, Southampton, United Kingdom,School of Biological Sciences, University of Southampton, Southampton, United Kingdom
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8
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Salem BS, Lamanna MC, O'Connor PM, El-Qot GM, Shaker F, Thabet WA, El-Sayed S, Sallam HM. First definitive record of Abelisauridae (Theropoda: Ceratosauria) from the Cretaceous Bahariya Formation, Bahariya Oasis, Western Desert of Egypt. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220106. [PMID: 35706658 PMCID: PMC9174736 DOI: 10.1098/rsos.220106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 05/11/2022] [Indexed: 05/03/2023]
Abstract
Numerous non-avian theropod dinosaur fossils have been reported from the Upper Cretaceous (Cenomanian) Bahariya Formation, Bahariya Oasis, Western Desert of Egypt, but unambiguous materials of Abelisauridae have yet to be documented. Here we report Mansoura University Vertebrate Paleontology Center (MUVP) specimen 477, an isolated, well-preserved tenth cervical vertebra of a medium-sized abelisaurid from the Bahariya Formation. The new vertebra shows affinities with those of other Upper Cretaceous abelisaurids from Madagascar and South America, such as Majungasaurus crenatissimus, Carnotaurus sastrei, Viavenator exxoni and a generically indeterminate Patagonian specimen (Museo Padre Molina specimen 99). Phylogenetic analysis recovers the Bahariya form within Abelisauridae, either in a polytomy of all included abelisaurids (strict consensus tree) or as an early branching member of the otherwise South American clade Brachyrostra (50% majority rule consensus tree). MUVP 477, therefore, represents the first confirmed abelisaurid fossil from the Bahariya Formation and the oldest definitive record of the clade from Egypt and northeastern Africa more generally. The new vertebra demonstrates the wide geographical distribution of Abelisauridae across North Africa during the middle Cretaceous and augments the already extraordinarily diverse large-bodied theropod assemblage of the Bahariya Formation, a record that also includes representatives of Spinosauridae, Carcharodontosauridae and Bahariasauridae.
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Affiliation(s)
- Belal S. Salem
- Department of Geology, Faculty of Science, Benha University, Benha, Egypt
- Mansoura University Vertebrate Paleontology Center (MUVP), Department of Geology, Faculty of Science, Mansoura University, Mansoura, Egypt
- Department of Biological Sciences, Ohio University, 228 Irvine Hall, Athens, OH, USA
- Ohio Center for Ecological and Evolutionary Studies, Ohio University, Athens, OH, USA
| | - Matthew C. Lamanna
- Section of Vertebrate Paleontology, Carnegie Museum of Natural History, Pittsburgh, PA, USA
| | - Patrick M. O'Connor
- Ohio Center for Ecological and Evolutionary Studies, Ohio University, Athens, OH, USA
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Gamal M. El-Qot
- Department of Geology, Faculty of Science, Benha University, Benha, Egypt
| | - Fatma Shaker
- Department of Geology, Faculty of Science, Benha University, Benha, Egypt
| | | | - Sanaa El-Sayed
- Mansoura University Vertebrate Paleontology Center (MUVP), Department of Geology, Faculty of Science, Mansoura University, Mansoura, Egypt
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Hesham M. Sallam
- Mansoura University Vertebrate Paleontology Center (MUVP), Department of Geology, Faculty of Science, Mansoura University, Mansoura, Egypt
- Institute of Global Health and Human Ecology (I-GHHE), School of Sciences and Engineering, American University in Cairo, New Cairo, Egypt
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9
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Mateus O, Estraviz-López D. A new theropod dinosaur from the early cretaceous (Barremian) of Cabo Espichel, Portugal: Implications for spinosaurid evolution. PLoS One 2022; 17:e0262614. [PMID: 35171930 PMCID: PMC8849621 DOI: 10.1371/journal.pone.0262614] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 12/23/2021] [Indexed: 12/01/2022] Open
Abstract
Spinosaurids are some of the most enigmatic Mesozoic theropod dinosaurs due to their unique adaptations to aquatic environments and their relative scarcity. Their taxonomy has proven to be especially problematic. Recent discoveries from Western Europe in general, specifically Iberia, provide some of the best specimens for the understanding of their phylogeny, leading to the description of the spinosaurid Vallibonavenatrix cani and the recognition of the Iberian dinosaur Camarillasaurus cirugedae as one of them. Portuguese associated spinosaurid remains (ML1190) from the Papo Seco Formation (early Barremian) were previously assigned to Baryonyx walkeri but new material recovered in 2020 along with new phylogenetic analyses suggests a different phylogenetic placement, making their revision necessary. Here we show that these remains are not attributable to Baryonyx walkeri, but to a new genus and species, Iberospinus natarioi, gen. et sp. nov. The new taxon is characterized by the presence of a single Meckelian foramen in the Meckelian sulcus, a straight profile of the ventral surface of the dentary and a distal thickening of the acromion process of the pubis between other characters. Iberospinus natarioi is recovered as a sister taxon of the clade formed by Baryonyx and Suchomimus, and outside Spinosaurinae when Vallibonaventrix cani is excluded from the analysis. The description of this taxon reinforces Iberia as a hotspot for spinosaur biodiversity, with several endemic taxa for the region. As expected for the clade, the dentary displays a highly vascularized neurovascular network. The morphometric analysis of parts of the skeleton (pedal phalanx and caudal vertebrae, among others) shows an intermediate condition between basal tetanurans and spinosaurines.
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Affiliation(s)
- Octávio Mateus
- GEOBIOTEC, Department of Earth Sciences, NOVA School of Science and Technology, Caparica, Portugal
- Museu da Lourinhã, Lourinhã, Portugal
| | - Darío Estraviz-López
- GEOBIOTEC, Department of Earth Sciences, NOVA School of Science and Technology, Caparica, Portugal
- Museu da Lourinhã, Lourinhã, Portugal
- * E-mail:
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10
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Sereno PC, Myhrvold N, Henderson DM, Fish FE, Vidal D, Baumgart SL, Keillor TM, Formoso KK, Conroy LL. Spinosaurus is not an aquatic dinosaur. eLife 2022; 11:80092. [PMID: 36448670 PMCID: PMC9711522 DOI: 10.7554/elife.80092] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 10/05/2022] [Indexed: 12/03/2022] Open
Abstract
A predominantly fish-eating diet was envisioned for the sail-backed theropod dinosaur Spinosaurus aegyptiacus when its elongate jaws with subconical teeth were unearthed a century ago in Egypt. Recent discovery of the high-spined tail of that skeleton, however, led to a bolder conjecture that S. aegyptiacus was the first fully aquatic dinosaur. The 'aquatic hypothesis' posits that S. aegyptiacus was a slow quadruped on land but a capable pursuit predator in coastal waters, powered by an expanded tail. We test these functional claims with skeletal and flesh models of S. aegyptiacus. We assembled a CT-based skeletal reconstruction based on the fossils, to which we added internal air and muscle to create a posable flesh model. That model shows that on land S. aegyptiacus was bipedal and in deep water was an unstable, slow-surface swimmer (<1 m/s) too buoyant to dive. Living reptiles with similar spine-supported sails over trunk and tail are used for display rather than aquatic propulsion, and nearly all extant secondary swimmers have reduced limbs and fleshy tail flukes. New fossils also show that Spinosaurus ranged far inland. Two stages are clarified in the evolution of Spinosaurus, which is best understood as a semiaquatic bipedal ambush piscivore that frequented the margins of coastal and inland waterways.
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Affiliation(s)
- Paul C Sereno
- 1Department of Organismal Biology, University of ChicagoChicagoUnited States,Committee on Evolutionary Biology, University of ChicagoChicagoUnited States
| | | | | | - Frank E Fish
- Department of Biology, West Chester UniversityWest ChesterUnited States
| | | | | | - Tyler M Keillor
- 1Department of Organismal Biology, University of ChicagoChicagoUnited States
| | - Kiersten K Formoso
- Department of Earth Sciences, University of Southern CaliforniaLos AngelesUnited States,Dinosaur Institute, Natural History Museum of Los Angeles CountyLos AngelesUnited States
| | - Lauren L Conroy
- 1Department of Organismal Biology, University of ChicagoChicagoUnited States
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11
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Barker CT, Hone DWE, Naish D, Cau A, Lockwood JAF, Foster B, Clarkin CE, Schneider P, Gostling NJ. New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae. Sci Rep 2021; 11:19340. [PMID: 34588472 PMCID: PMC8481559 DOI: 10.1038/s41598-021-97870-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 08/26/2021] [Indexed: 11/18/2022] Open
Abstract
Spinosaurids are among the most distinctive and yet poorly-known of large-bodied theropod dinosaurs, a situation exacerbated by their mostly fragmentary fossil record and competing views regarding their palaeobiology. Here, we report two new Early Cretaceous spinosaurid specimens from the Wessex Formation (Barremian) of the Isle of Wight. Large-scale phylogenetic analyses using parsimony and Bayesian techniques recover the pair in a new clade within Baryonychinae that also includes the hypodigm of the African spinosaurid Suchomimus. Both specimens represent distinct and novel taxa, herein named Ceratosuchops inferodios gen. et sp. nov. and Riparovenator milnerae gen. et sp. nov. A palaeogeographic reconstruction suggests a European origin for Spinosauridae, with at least two dispersal events into Africa. These new finds provide welcome information on poorly sampled areas of spinosaurid anatomy, suggest that sympatry was present and potentially common in baryonychines and spinosaurids as a whole, and contribute to updated palaeobiogeographic reconstructions for the clade.
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Affiliation(s)
- Chris T Barker
- Institute for Life Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, UK.
- Faculty of Engineering and Physical Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, UK.
| | - David W E Hone
- School of Biological and Behavioural Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Darren Naish
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, UK
| | | | - Jeremy A F Lockwood
- School of Environment, Geography and Geosciences, University of Portsmouth, Burnaby Road, Portsmouth, PO1 3QL, UK
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | | | - Claire E Clarkin
- Institute for Life Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, UK
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, UK
| | - Philipp Schneider
- Bioengineering Science Research Group, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
- High-Performance Vision Systems, Center for Vision, Automation and Control, AIT Austrian Institute of Technology, Vienna, Austria
| | - Neil J Gostling
- Institute for Life Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, UK.
- School of Biological Sciences, Faculty of Environment and Life Sciences, University of Southampton, University Road, Southampton, SO17 1BJ, UK.
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12
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Griffin CT, Stocker MR, Colleary C, Stefanic CM, Lessner EJ, Riegler M, Formoso K, Koeller K, Nesbitt SJ. Assessing ontogenetic maturity in extinct saurian reptiles. Biol Rev Camb Philos Soc 2020; 96:470-525. [PMID: 33289322 DOI: 10.1111/brv.12666] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 01/06/2023]
Abstract
Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life-history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least-inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260-million-year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. 'juvenile', 'mature') and provide routes for better clarity and cross-study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method-specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, 'Ontogenetic Assessment', be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well-represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well-constrained, empirically tested methods.
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Affiliation(s)
- Christopher T Griffin
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Michelle R Stocker
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Caitlin Colleary
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Vertebrate Paleontology, Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, OH, 44106, U.S.A
| | - Candice M Stefanic
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Anatomical Sciences, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, U.S.A
| | - Emily J Lessner
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Pathology and Anatomical Sciences, University of Missouri, 1 Hospital Drive, Columbia, MO, 65212, U.S.A
| | - Mitchell Riegler
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL, 32611, U.S.A
| | - Kiersten Formoso
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA, 90089, U.S.A
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 W Exposition Boulevard, Los Angeles, CA, 90007, U.S.A
| | - Krista Koeller
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611, U.S.A
| | - Sterling J Nesbitt
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
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13
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Li Y, Ruta M, Wills MA. Craniodental and Postcranial Characters of Non-Avian Dinosauria Often Imply Different Trees. Syst Biol 2020; 69:638-659. [PMID: 31769837 PMCID: PMC7302058 DOI: 10.1093/sysbio/syz077] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/08/2019] [Accepted: 11/18/2019] [Indexed: 12/28/2022] Open
Abstract
Despite the increasing importance of molecular sequence data, morphology still makes an important contribution to resolving the phylogeny of many groups, and is the only source of data for most fossils. Most systematists sample morphological characters as broadly as possible on the principle of total evidence. However, it is not uncommon for sampling to be focused on particular aspects of anatomy, either because characters therein are believed to be more informative, or because preservation biases restrict what is available. Empirically, the optimal trees from partitions of morphological data sets often represent significantly different hypotheses of relationships. Previous work on hard-part versus soft-part characters across animal phyla revealed significant differences in about a half of sampled studies. Similarly, studies of the craniodental versus postcranial characters of vertebrates revealed significantly different trees in about one-third of cases, with the highest rates observed in non-avian dinosaurs. We test whether this is a generality here with a much larger sample of 81 published data matrices across all major dinosaur groups. Using the incongruence length difference test and two variants of the incongruence relationship difference test, we found significant incongruence in about 50% of cases. Incongruence is not uniformly distributed across major dinosaur clades, being highest (63%) in Theropoda and lowest (25%) in Thyreophora. As in previous studies, our partition tests show some sensitivity to matrix dimensions and the amount and distribution of missing entries. Levels of homoplasy and retained synapomorphy are similar between partitions, such that incongruence must partly reflect differences in patterns of homoplasy between partitions, which may itself be a function of modularity and mosaic evolution. Finally, we implement new tests to determine which partition yields trees most similar to those from the entire matrix. Despite no bias across dinosaurs overall, there are striking differences between major groups. The craniodental characters of Ornithischia and the postcranial characters of Saurischia yield trees most similar to the "total evidence" trees derived from the entire matrix. Trees from these same character partitions also tend to be most stratigraphically congruent: a mutual consilience suggesting that those partitions yield more accurate trees. [Dinosauria; homoplasy; partition homogeneity.].
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Affiliation(s)
- Yimeng Li
- Department of Biology & Biochemistry, The Milner Centre for Evolution, The University of Bath, The Avenue, Claverton Down, Bath BA2 7AY, UK
| | - Marcello Ruta
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln LN6 7DL, UK
| | - Matthew A Wills
- Department of Biology & Biochemistry, The Milner Centre for Evolution, The University of Bath, The Avenue, Claverton Down, Bath BA2 7AY, UK
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14
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Schade M, Rauhut OWM, Evers SW. Neuroanatomy of the spinosaurid Irritator challengeri (Dinosauria: Theropoda) indicates potential adaptations for piscivory. Sci Rep 2020; 10:9259. [PMID: 32518236 PMCID: PMC7283278 DOI: 10.1038/s41598-020-66261-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/18/2020] [Indexed: 11/18/2022] Open
Abstract
Spinosauridae, a theropod group characterized by elongated snouts, conical teeth, enlarged forelimbs, and often elongated neural spines, show evidence for semiaquatic adaptations and piscivory. It is currently debated if these animals represent terrestrial carnivores with adaptations for a piscivorous diet, or if they largely lived and foraged in aquatic habitats. The holotype of Irritator challengeri, a nearly complete skull from the late Early Cretaceous Santana Formation of northeastern Brazil, includes one of the few preserved spinosaurid braincases and can provide insights into neuroanatomical structures that might be expected to reflect ecological affinities. We generated digital models of the neuroanatomical cavities within the braincase, using computer tomography (CT) data. The cranial endocast of Irritator is generally similar to that of other non-maniraptoriform theropods, with weakly developed distinctions of hindbrain and midbrain features, relatively pronounced cranial flexures and relatively long olfactory tracts. The endosseous labyrinth has a long anterior semicircular canal, a posteriorly inclined common crus and a very large floccular recess fills the area between the semicircular canals. These features indicate that Irritator had the ability for fast and well-controlled pitch-down head movements. The skull table and lateral semicircular canal plane are strongly angled to one another, suggesting a downward angling of approximately 45° of the snout, which reduces interference of the snout with the field of vision of Irritator. These neuroanatomical features are consistent with fast, downward snatching movements in the act of predation, such as are needed for piscivory.
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Affiliation(s)
- Marco Schade
- Institute of Geography and Geology, Palaeontology and Historical Geology, University of Greifswald, 17489, Greifswald, Germany. .,Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität, 80333, München, Germany.
| | - Oliver W M Rauhut
- Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität, 80333, München, Germany.,Bayerische Staatssammlung für Paläntologie und Geologie, Staatliche Naturwissenschaftliche Sammlungen Bayerns (SNSB), 80333, München, Germany.,GeoBioCenter, Ludwig-Maximilians-Universität, 80333, München, Germany
| | - Serjoscha W Evers
- Department of Geosciences, University of Fribourg, 17000, Fribourg, Switzerland
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15
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Tail-propelled aquatic locomotion in a theropod dinosaur. Nature 2020; 581:67-70. [PMID: 32376955 DOI: 10.1038/s41586-020-2190-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 02/19/2020] [Indexed: 11/08/2022]
Abstract
In recent decades, intensive research on non-avian dinosaurs has strongly suggested that these animals were restricted to terrestrial environments1. Historical proposals that some groups, such as sauropods and hadrosaurs, lived in aquatic environments2,3 were abandoned decades ago4-6. It has recently been argued that at least some of the spinosaurids-an unusual group of large-bodied theropods of the Cretaceous era-were semi-aquatic7,8, but this idea has been challenged on anatomical, biomechanical and taphonomic grounds, and remains controversial9-11. Here we present unambiguous evidence for an aquatic propulsive structure in a dinosaur, the giant theropod Spinosaurus aegyptiacus7,12. This dinosaur has a tail with an unexpected and unique shape that consists of extremely tall neural spines and elongate chevrons, which forms a large, flexible fin-like organ capable of extensive lateral excursion. Using a robotic flapping apparatus to measure undulatory forces in physical models of different tail shapes, we show that the tail shape of Spinosaurus produces greater thrust and efficiency in water than the tail shapes of terrestrial dinosaurs and that these measures of performance are more comparable to those of extant aquatic vertebrates that use vertically expanded tails to generate forward propulsion while swimming. These results are consistent with the suite of adaptations for an aquatic lifestyle and piscivorous diet that have previously been documented for Spinosaurus7,13,14. Although developed to a lesser degree, aquatic adaptations are also found in other members of the spinosaurid clade15,16, which had a near-global distribution and a stratigraphic range of more than 50 million years14, pointing to a substantial invasion of aquatic environments by dinosaurs.
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16
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Ibrahim N, Sereno PC, Varricchio DJ, Martill DM, Dutheil DB, Unwin DM, Baidder L, Larsson HC, Zouhri S, Kaoukaya A. Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco. Zookeys 2020; 928:1-216. [PMID: 32362741 PMCID: PMC7188693 DOI: 10.3897/zookeys.928.47517] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 03/02/2020] [Indexed: 11/30/2022] Open
Abstract
The geological and paleoenvironmental setting and the vertebrate taxonomy of the fossiliferous, Cenomanian-age deltaic sediments in eastern Morocco, generally referred to as the "Kem Kem beds", are reviewed. These strata are recognized here as the Kem Kem Group, which is composed of the lower Gara Sbaa and upper Douira formations. Both formations have yielded a similar fossil vertebrate assemblage of predominantly isolated elements pertaining to cartilaginous and bony fishes, turtles, crocodyliforms, pterosaurs, and dinosaurs, as well as invertebrate, plant, and trace fossils. These fossils, now in collections around the world, are reviewed and tabulated. The Kem Kem vertebrate fauna is biased toward large-bodied carnivores including at least four large-bodied non-avian theropods (an abelisaurid, Spinosaurus, Carcharodontosaurus, and Deltadromeus), several large-bodied pterosaurs, and several large crocodyliforms. No comparable modern terrestrial ecosystem exists with similar bias toward large-bodied carnivores. The Kem Kem vertebrate assemblage, currently the best documented association just prior to the onset of the Cenomanian-Turonian marine transgression, captures the taxonomic diversity of a widespread northern African fauna better than any other contemporary assemblage from elsewhere in Africa.
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Affiliation(s)
- Nizar Ibrahim
- Department of Biology, University of Detroit Mercy, Detroit, Michigan 48221, USA
| | - Paul C. Sereno
- Department of Organismal Biology and Anatomy and Committee on Evolutionary Biology, University of Chicago, Chicago, Illinois 60637, USA
| | - David J. Varricchio
- Department of Earth Sciences, Montana State University, Bozeman, Montana 59717, USA
| | - David M. Martill
- School of the Environment, Geography and Geological Sciences, University of Portsmouth, Portsmouth PO1 3QL, UK
| | - Didier B. Dutheil
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, UMR7207 (CNRS-MNHN-UPMC), Muséum national d’Histoire naturelle, 75005 Paris, France
| | - David M. Unwin
- School of Museum Studies, University of Leicester, Leicester LE1 7RF, UK
| | - Lahssen Baidder
- Laboratoire Géosciences, Département de Géologie, Faculté des Sciences Aïn Chock, Université Hassan II, Casablanca, Morocco
| | | | - Samir Zouhri
- Laboratoire de Biodiversité et Santé, Faculté des Sciences Aïn Chock, Université Hassan II, Casablanca, Morocco
| | - Abdelhadi Kaoukaya
- Laboratoire Géosciences, Département de Géologie, Faculté des Sciences Aïn Chock, Université Hassan II, Casablanca, Morocco
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17
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Hassler A, Martin JE, Amiot R, Tacail T, Godet FA, Allain R, Balter V. Calcium isotopes offer clues on resource partitioning among Cretaceous predatory dinosaurs. Proc Biol Sci 2019; 285:rspb.2018.0197. [PMID: 29643213 DOI: 10.1098/rspb.2018.0197] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/15/2018] [Indexed: 11/12/2022] Open
Abstract
Large predators are overabundant in mid-Cretaceous continental dinosaur assemblages of North Africa. Such unbalanced ecosystem structure involves, among predatory dinosaurs, typical abelisaurid or carcharodontosaurid theropods co-occurring with long-snouted spinosaurids of debated ecology. Here, we report calcium (Ca) isotope values from tooth enamel (expressed as δ44/42Ca) to investigate resource partitioning in mid-Cretaceous assemblages from Niger (Gadoufaoua) and Morocco (Kem Kem Beds). In both assemblages, spinosaurids display a distinct isotopic signature, the most negative in our dataset. This distinct taxonomic clustering in Ca isotope values observed between spinosaurids and other predators provides unambiguous evidence for niche partitioning at the top of the trophic chains: spinosaurids foraged on aquatic environments while abelisaurid and carcharodontosaurid theropods relied almost exclusively on terrestrial resources.
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Affiliation(s)
- A Hassler
- Univ. Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276 Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, F-69007 46 Allée d'Italie, Lyon, France
| | - J E Martin
- Univ. Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276 Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, F-69007 46 Allée d'Italie, Lyon, France
| | - R Amiot
- Univ. Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276 Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, F-69007 46 Allée d'Italie, Lyon, France
| | - T Tacail
- Univ. Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276 Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, F-69007 46 Allée d'Italie, Lyon, France
| | - F Arnaud Godet
- Univ. Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276 Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, F-69007 46 Allée d'Italie, Lyon, France
| | - R Allain
- Sorbonne Universités-CR2P-MNHN, CNRS, UPMC-Paris 6, Muséum National d'Histoire Naturelle, 57 Rue Cuvier, CP 38, 75231 Paris Cedex 05, France
| | - V Balter
- Univ. Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5276 Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, F-69007 46 Allée d'Italie, Lyon, France
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18
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Schwarz D, Kundrát M, Tischlinger H, Dyke G, Carney RM. Ultraviolet light illuminates the avian nature of the Berlin Archaeopteryx skeleton. Sci Rep 2019; 9:6518. [PMID: 31019224 PMCID: PMC6482141 DOI: 10.1038/s41598-019-42823-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 11/22/2018] [Indexed: 11/08/2022] Open
Abstract
The question of whether the iconic avialan Archaeopteryx was capable of active flapping flight or only passive gliding is still unresolved. This study contributes to this debate by reporting on two key aspects of this fossil that are visible under ultraviolet (UV) light. In contrast to previous studies, we show that most of the vertebral column of the Berlin Archaeopteryx possesses intraosseous pneumaticity, and that pneumatic structures also extend beyond the anterior thoracic vertebrae in other specimens of Archaeopteryx. With a minimum Pneumaticity Index (PI) of 0.39, Archaeopteryx had a much more lightweight skeleton than has been previously reported, comprising an air sac-driven respiratory system with the potential for a bird-like, high-performance metabolism. The neural spines of the 16th to 22nd presacral vertebrae in the Berlin Archaeopteryx are bridged by interspinal ossifications, and form a rigid notarium-like structure similar to the condition seen in modern birds. This reinforced vertebral column, combined with the extensive development of air sacs, suggests that Archaeopteryx was capable of flapping its wings for cursorial and/or aerial locomotion.
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Affiliation(s)
- Daniela Schwarz
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, 10115, Berlin, Germany.
| | - Martin Kundrát
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, University of Pavol Jozef Šafárik, 04154, Košice, Slovakia.
| | | | - Gareth Dyke
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, University of Pavol Jozef Šafárik, 04154, Košice, Slovakia
- Department of Geology, Babes-Bolyai University, Cluj-Napoca, Romania
| | - Ryan M Carney
- Department of Integrative Biology, University of South Florida, 33620, Tampa, FL, USA
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19
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Brougham T, Smith ET, Bell PR. New theropod (Tetanurae: Avetheropoda) material from the 'mid'-Cretaceous Griman Creek Formation at Lightning Ridge, New South Wales, Australia [corrected]. ROYAL SOCIETY OPEN SCIENCE 2019; 6:180826. [PMID: 30800346 PMCID: PMC6366187 DOI: 10.1098/rsos.180826] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 12/17/2018] [Indexed: 05/12/2023]
Abstract
The limited fossil record of Australian Cretaceous theropods is dominated by megaraptorids, reported from associated and isolated material from the Early Cretaceous of Victoria and the 'Mid'-Cretaceous of central-north New South Wales and central Queensland. Here, we report on new postcranial theropod material from the early Late Cretaceous Griman Creek Formation at Lightning Ridge. Among this new material is an associated set consisting of two anterior caudal vertebrae and a pubic peduncle of the ilium, to which a morphologically similar partial vertebral centra from a separate locality is tentatively referred. These elements display a combination of characteristics that are present in megaraptorid and carcharodontosaurid theropods, including camellate internal organization of the vertebral centra, ventrally keeled anterior caudal centra and a pubic peduncle of the ilium with a ventral surface approximately twice as long anteroposteriorly as mediolaterally wide. Unfortunately, a lack of unambiguous synapomorphies precludes accurate taxonomic placement; however, avetheropodan affinities are inferred. This new material represents the second instance of a medium-sized theropod from this interval, and only the third known example of associated preservation in an Australian theropod. Additional isolated theropod material is also described, including an avetheropodan femoral head that shows similarities to Allosaurus and Australovenator, and a mid-caudal vertebral centrum bearing pneumatic foraminae and extensive camellae that is referrable to Megaraptora and represents the first axial skeletal element of a megaraptorid described from Lightning Ridge.
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Affiliation(s)
- Tom Brougham
- School of Environmental and Rural Science, University of New England, Armidale 2351, New South Wales, Australia
- Author for correspondence: Tom Brougham e-mail:
| | - Elizabeth T. Smith
- Australian Opal Centre, 3/11 Morilla Street, Lightning Ridge 2834, New South Wales, Australia
| | - Phil R. Bell
- School of Environmental and Rural Science, University of New England, Armidale 2351, New South Wales, Australia
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20
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Maganuco S, Dal Sasso C. The smallest biggest theropod dinosaur: a tiny pedal ungual of a juvenile Spinosaurus from the Cretaceous of Morocco. PeerJ 2018; 6:e4785. [PMID: 29868253 PMCID: PMC5984586 DOI: 10.7717/peerj.4785] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 04/27/2018] [Indexed: 11/20/2022] Open
Abstract
We describe a nearly complete pedal ungual phalanx, discovered in the Kem Kem Beds (Cenomanian) of Tafilalt region, south-eastern Morocco. The bone is symmetric, pointed, low, elongate, and almost flat ventrally in lateral aspect. This peculiar morphology allows to refer the specimen to the smallest known individual of the genus Spinosaurus. The bone belongs to an early juvenile individual and it is proportionally identical to the ungual of the third digit of a large partial skeleton recently found, suggesting an isometric growth for this part of the pes and the retention of peculiar locomotor adaptations—such as traversing soft substrates or paddling—during the entire lifespan.
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21
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Tennant JP, Chiarenza AA, Baron M. How has our knowledge of dinosaur diversity through geologic time changed through research history? PeerJ 2018; 6:e4417. [PMID: 29479504 PMCID: PMC5822849 DOI: 10.7717/peerj.4417] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 02/06/2018] [Indexed: 11/20/2022] Open
Abstract
Assessments of dinosaur macroevolution at any given time can be biased by the historical publication record. Recent studies have analysed patterns in dinosaur diversity that are based on secular variations in the numbers of published taxa. Many of these have employed a range of approaches that account for changes in the shape of the taxonomic abundance curve, which are largely dependent on databases compiled from the primary published literature. However, how these ‘corrected’ diversity patterns are influenced by the history of publication remains largely unknown. Here, we investigate the influence of publication history between 1991 and 2015 on our understanding of dinosaur evolution using raw diversity estimates and shareholder quorum subsampling for the three major subgroups: Ornithischia, Sauropodomorpha, and Theropoda. We find that, while sampling generally improves through time, there remain periods and regions in dinosaur evolutionary history where diversity estimates are highly volatile (e.g. the latest Jurassic of Europe, the mid-Cretaceous of North America, and the Late Cretaceous of South America). Our results show that historical changes in database compilation can often substantially influence our interpretations of dinosaur diversity. ‘Global’ estimates of diversity based on the fossil record are often also based on incomplete, and distinct regional signals, each subject to their own sampling history. Changes in the record of taxon abundance distribution, either through discovery of new taxa or addition of existing taxa to improve sampling evenness, are important in improving the reliability of our interpretations of dinosaur diversity. Furthermore, the number of occurrences and newly identified dinosaurs is still rapidly increasing through time, suggesting that it is entirely possible for much of what we know about dinosaurs at the present to change within the next 20 years.
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Affiliation(s)
- Jonathan P Tennant
- Department of Earth Science and Engineering, Imperial College London, London, UK
| | | | - Matthew Baron
- Department of Earth Science, University of Cambridge, Cambridge, UK.,Earth Sciences Department, Natural History Museum, London, UK
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Rauhut OWM, Foth C, Tischlinger H. The oldest Archaeopteryx (Theropoda: Avialiae): a new specimen from the Kimmeridgian/Tithonian boundary of Schamhaupten, Bavaria. PeerJ 2018; 6:e4191. [PMID: 29383285 PMCID: PMC5788062 DOI: 10.7717/peerj.4191] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/04/2017] [Indexed: 11/25/2022] Open
Abstract
The iconic primeval bird Archaeopteryx was so far mainly known from the Altmühltal Formation (early Tithonian) of Bavaria, southern Germany, with one specimen having been found in the overlying Mörnsheim Formation. A new specimen (the 12th skeletal specimen) from the earliest Tithonian Painten Formation of Schamhaupten (Bavaria) represents the so far oldest representative of the genus. The new specimen shows several interesting anatomical details, including the presence of a postorbital in contact with the jugal, the presence of a separate prefrontal and coronoid, and opisthocoelous mid-cervical vertebrae. Based on observations on the new specimen, we discuss several problematic issues concerning Archaeopteryx, including the monophyly and diagnosis of the genus, the absence/presence of the sternum, the position of the gastralia, and variation in morphometrics and dental morphology in that genus. Based on a new diagnosis for the genus Archaeopteryx, the Berlin, Eichstätt, Solnhofen, Munich, Daiting, Thermopolis, 11th, and 12th specimens can be referred to this genus with high certainty. The Maxberg specimen is very probably also an Archaeopteryx, based on overall similarity, although none of the diagnostic characters can be evaluated with certainty. The ninth specimen (‘chicken wing’) might be Archaeopteryx, but cannot be referred to the genus with any certainty. In comparison with other paravians, the presence of distally thickened anterior pectoral ribs indicates that a rather large cartilagenous sternum was present in this taxon. In contrast to non-opisthopubic theropods, opisthopubic taxa, such as Archaeopteryx and many other paravians, have the posterior end of the gastral basket preserved at about half-length of the pubis, which might reflect the post-mortem collapse of enlarged abdominal air sacs in these taxa. Specimens that can be referred to Archaeopteryx show a high amount of variation, both in the morphometrics of the limb bones as well as in the dentition. In respect to the latter aspect, variation is found in tooth number, spacing, orientation, and morphology, with no two specimens showing the exact same pattern. The significance of this variation is unclear, and possible explanations reach from high intraspecific (and possibly ontogenetic and/or sexual dimorphic) variation to the possibility that the known specimens represent a ‘species flock’ of Archaeopteryx, possibly due to island speciation after the initial dispersal of the genus into the Solnhofen Archipelago.
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Affiliation(s)
- Oliver W M Rauhut
- SNSB-Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Germany.,Department of Earth and Environmental Sciences, Ludwig-Maximilians University, Munich, Germany.,GeoBioCenter, Ludwig-Maximilians University, Munich, Germany
| | - Christian Foth
- Department of Geosciences, Université de Fribourg, Fribourg, Switzerland.,Staatliches Museum für Naturkunde, Stuttgart, Germany
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Sales MAF, Schultz CL. Spinosaur taxonomy and evolution of craniodental features: Evidence from Brazil. PLoS One 2017; 12:e0187070. [PMID: 29107966 PMCID: PMC5673194 DOI: 10.1371/journal.pone.0187070] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 10/12/2017] [Indexed: 12/03/2022] Open
Abstract
Fossil sites from Brazil have yielded specimens of spinosaurid theropods, among which the most informative include the cranial remains of Irritator, Angaturama, and Oxalaia. In this work some of their craniodental features are reinterpreted, providing new data for taxonomic and evolutionary issues concerning this particular clade of dinosaurs. The mesial-most tooth of the left maxilla of the holotype of Irritator is regarded as representing the third tooth position, which is also preserved in the holotype of Angaturama. Thus, both specimens cannot belong to the same individual, contrary to previous assumptions, although they could have been the same taxon. In addition, the position of the external nares of Irritator is more comparable to those of Baryonyx and Suchomimus instead of other spinosaurine spinosaurids. In fact, with regards to some craniodental features, Brazilian taxa represent intermediate conditions between Baryonychinae and Spinosaurinae. Such a scenario is corroborated by our cladistic results, which also leave open the possibility of the former subfamily being non-monophyletic. Furthermore, the differences between spinosaurids regarding the position and size of the external nares might be related to distinct feeding habits and degrees of reliance on olfaction. Other issues concerning the evolution and taxonomy of Spinosauridae require descriptions of additional material for their clarification.
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Affiliation(s)
- Marcos A. F. Sales
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil
- Instituto Federal de Educação, Ciência e Tecnologia do Ceará (IFCE), Fortaleza, Ceará, Brazil
| | - Cesar L. Schultz
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil
- Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil
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Tennant JP, Mannion PD, Upchurch P, Sutton MD, Price GD. Biotic and environmental dynamics through the Late Jurassic-Early Cretaceous transition: evidence for protracted faunal and ecological turnover. Biol Rev Camb Philos Soc 2017; 92:776-814. [PMID: 26888552 PMCID: PMC6849608 DOI: 10.1111/brv.12255] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 01/18/2016] [Accepted: 01/20/2016] [Indexed: 11/29/2022]
Abstract
The Late Jurassic to Early Cretaceous interval represents a time of environmental upheaval and cataclysmic events, combined with disruptions to terrestrial and marine ecosystems. Historically, the Jurassic/Cretaceous (J/K) boundary was classified as one of eight mass extinctions. However, more recent research has largely overturned this view, revealing a much more complex pattern of biotic and abiotic dynamics than has previously been appreciated. Here, we present a synthesis of our current knowledge of Late Jurassic-Early Cretaceous events, focusing particularly on events closest to the J/K boundary. We find evidence for a combination of short-term catastrophic events, large-scale tectonic processes and environmental perturbations, and major clade interactions that led to a seemingly dramatic faunal and ecological turnover in both the marine and terrestrial realms. This is coupled with a great reduction in global biodiversity which might in part be explained by poor sampling. Very few groups appear to have been entirely resilient to this J/K boundary 'event', which hints at a 'cascade model' of ecosystem changes driving faunal dynamics. Within terrestrial ecosystems, larger, more-specialised organisms, such as saurischian dinosaurs, appear to have suffered the most. Medium-sized tetanuran theropods declined, and were replaced by larger-bodied groups, and basal eusauropods were replaced by neosauropod faunas. The ascent of paravian theropods is emphasised by escalated competition with contemporary pterosaur groups, culminating in the explosive radiation of birds, although the timing of this is obfuscated by biases in sampling. Smaller, more ecologically diverse terrestrial non-archosaurs, such as lissamphibians and mammaliaforms, were comparatively resilient to extinctions, instead documenting the origination of many extant groups around the J/K boundary. In the marine realm, extinctions were focused on low-latitude, shallow marine shelf-dwelling faunas, corresponding to a significant eustatic sea-level fall in the latest Jurassic. More mobile and ecologically plastic marine groups, such as ichthyosaurs, survived the boundary relatively unscathed. High rates of extinction and turnover in other macropredaceous marine groups, including plesiosaurs, are accompanied by the origin of most major lineages of extant sharks. Groups which occupied both marine and terrestrial ecosystems, including crocodylomorphs, document a selective extinction in shallow marine forms, whereas turtles appear to have diversified. These patterns suggest that different extinction selectivity and ecological processes were operating between marine and terrestrial ecosystems, which were ultimately important in determining the fates of many key groups, as well as the origins of many major extant lineages. We identify a series of potential abiotic candidates for driving these patterns, including multiple bolide impacts, several episodes of flood basalt eruptions, dramatic climate change, and major disruptions to oceanic systems. The J/K transition therefore, although not a mass extinction, represents an important transitional period in the co-evolutionary history of life on Earth.
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Affiliation(s)
- Jonathan P. Tennant
- Department of Earth Science and EngineeringImperial College LondonSouth KensingtonLondonSW7 2AZU.K.
| | - Philip D. Mannion
- Department of Earth Science and EngineeringImperial College LondonSouth KensingtonLondonSW7 2AZU.K.
| | - Paul Upchurch
- Department of Earth SciencesUniversity College LondonLondonWC1E 6BTU.K.
| | - Mark D. Sutton
- Department of Earth Science and EngineeringImperial College LondonSouth KensingtonLondonSW7 2AZU.K.
| | - Gregory D. Price
- School of Geography, Earth and Environmental SciencesPlymouth UniversityPlymouthPL4 8AAU.K.
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Meunier LMV, Larsson HCE. Revision and phylogenetic affinities ofElosuchus(Crocodyliformes). Zool J Linn Soc 2016. [DOI: 10.1111/zoj.12448] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Louise M. V. Meunier
- Redpath Museum; McGill University; Montreal QC H3A 0C4 Canada
- Department of Earth and Planetary Sciences; McGill University; Montreal QC H3A 0E8 Canada
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Young MT, Hastings AK, Allain R, Smith TJ. Revision of the enigmatic crocodyliformElosuchus felixide Lapparent de Broin, 2002 from the Lower-Upper Cretaceous boundary of Niger: potential evidence for an early origin of the clade Dyrosauridae. Zool J Linn Soc 2016. [DOI: 10.1111/zoj.12452] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Mark T. Young
- Grant Institute; School of GeoSciences; University of Edinburgh; The King's Buildings, James Hutton Road Edinburgh EH9 3FE UK
| | - Alexander K. Hastings
- Geiseltalsammlung, Zentralmagazin Naturwissenschaftlicher Sammlungen; Martin Luther Universität Halle-Wittenberg; Domplatz 4 06108 Halle (Saale) Germany
- Virginia Museum of Natural History; 21 Starling Avenue Martinsville VA 24112 USA
| | - Ronan Allain
- Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements (CR2P, UMR 7207); Sorbonne Universités-MNHN; CNRS, UPMC-Paris 6; Muséum National d'Histoire Naturelle; 57 rue Cuvier, CP38 F-75005 Paris France
| | - Thomas J. Smith
- Ocean and Earth Science; National Oceanography Centre; University of Southampton; European Way Southampton SO14 3ZH UK
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Rauhut OWM, Carrano MT. The theropod dinosaurElaphrosaurus bambergiJanensch, 1920, from the Late Jurassic of Tendaguru, Tanzania. Zool J Linn Soc 2016. [DOI: 10.1111/zoj.12425] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Oliver W. M. Rauhut
- SNSB; Bayerische Staatssammlung für Paläontologie und Geologie; Department of Earth and Environmental Sciences; GeoBioCenter; Ludwig-Maximilians-University; Richard-Wagner-Straße 10 D-80333 München Germany
| | - Matthew T. Carrano
- Department of Paleobiology; Smithsonian Institution; P.O. Box 37012, MRC 121 Washington DC 20013-7012 USA
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Chiarenza AA, Cau A. A large abelisaurid (Dinosauria, Theropoda) from Morocco and comments on the Cenomanian theropods from North Africa. PeerJ 2016; 4:e1754. [PMID: 26966675 PMCID: PMC4782726 DOI: 10.7717/peerj.1754] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 02/12/2016] [Indexed: 11/20/2022] Open
Abstract
We describe the partially preserved femur of a large-bodied theropod dinosaur from the Cenomanian “Kem Kem Compound Assemblage” (KKCA) of Morocco. The fossil is housed in the Museo Geologico e Paleontologico “Gaetano Giorgio Gemmellaro” in Palermo (Italy). The specimen is compared with the theropod fossil record from the KKCA and coeval assemblages from North Africa. The combination of a distally reclined head, a not prominent trochanteric shelf, distally placed lesser trochanter of stout, alariform shape, a stocky shaft with the fourth trochanter placed proximally, and rugose muscular insertion areas in the specimen distinguishes it from Carcharodontosaurus, Deltadromeus and Spinosaurus and supports referral to an abelisaurid. The estimated body size for the individual from which this femur was derived is comparable to Carnotaurus and Ekrixinatosaurus (up to 9 meters in length and 2 tons in body mass). This find confirms that abelisaurids had reached their largest body size in the “middle Cretaceous,” and that large abelisaurids coexisted with other giant theropods in Africa. We review the taxonomic status of the theropods from the Cenomanian of North Africa, and provisionally restrict the Linnean binomina Carcharodontosaurus iguidensis and Spinosaurus aegyptiacus to the type specimens. Based on comparisons among the theropod records from the Aptian-Cenomanian of South America and Africa, a partial explanation for the so-called “Stromer’s riddle” (namely, the coexistence of many large predatory dinosaurs in the “middle Cretaceous” record from North Africa) is offered in term of taphonomic artifacts among lineage records that were ecologically and environmentally non-overlapping. Although morphofunctional and stratigraphic evidence supports an ecological segregation between spinosaurids and the other lineages, the co-occurrence of abelisaurids and carcharodontosaurids, two groups showing several craniodental convergences that suggest direct resource competition, remains to be explained.
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Affiliation(s)
| | - Andrea Cau
- Earth, Life and Environmental Sciences, University of Bologna, Bologna, Italy; Geological and Palaeontological Museum "G. Capellini,"Bologna, Italy
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Hendrickx C, Mateus O, Buffetaut E. Morphofunctional Analysis of the Quadrate of Spinosauridae (Dinosauria: Theropoda) and the Presence of Spinosaurus and a Second Spinosaurine Taxon in the Cenomanian of North Africa. PLoS One 2016; 11:e0144695. [PMID: 26734729 PMCID: PMC4703214 DOI: 10.1371/journal.pone.0144695] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 11/20/2015] [Indexed: 11/30/2022] Open
Abstract
Six quadrate bones, of which two almost certainly come from the Kem Kem beds (Cenomanian, Upper Cretaceous) of south-eastern Morocco, are determined to be from juvenile and adult individuals of Spinosaurinae based on phylogenetic, geometric morphometric, and phylogenetic morphometric analyses. Their morphology indicates two morphotypes evidencing the presence of two spinosaurine taxa ascribed to Spinosaurus aegyptiacus and? Sigilmassasaurus brevicollis in the Cenomanian of North Africa, casting doubt on the accuracy of some recent skeletal reconstructions which may be based on elements from several distinct species. Morphofunctional analysis of the mandibular articulation of the quadrate has shown that the jaw mechanics was peculiar in Spinosauridae. In mature spinosaurids, the posterior parts of the two mandibular rami displaced laterally when the jaw was depressed due to a lateromedially oriented intercondylar sulcus of the quadrate. Such lateral movement of the mandibular ramus was possible due to a movable mandibular symphysis in spinosaurids, allowing the pharynx to be widened. Similar jaw mechanics also occur in some pterosaurs and living pelecanids which are both adapted to capture and swallow large prey items. Spinosauridae, which were engaged, at least partially, in a piscivorous lifestyle, were able to consume large fish and may have occasionally fed on other prey such as pterosaurs and juvenile dinosaurs.
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Affiliation(s)
- Christophe Hendrickx
- GeoBioTec, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- Museu da Lourinhã, Lourinhã, Portugal
| | - Octávio Mateus
- GeoBioTec, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- Museu da Lourinhã, Lourinhã, Portugal
| | - Eric Buffetaut
- CNRS (UMR 8538), Laboratoire de Géologie de l’École Normale Supérieure, PSL Research University, Paris, France
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