The cranial osteology and feeding ecology of the Metriorhynchid Crocodylomorph Genera <i>Dakosaurus</i> and <i>Plesiosuchus</i> from the late Jurassic of Europe

Background: Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodied, macrophagous metriorhynchid crocodylomorphs. Recent studies show that these genera were apex predators in marine ecosystems during the latter part of the Late Jurassic, with robust skulls and strong bite forces optimized for feeding on large prey. Methodology/Principal Findings: Here we present comprehensive osteological descriptions and systematic revisions of the type species of both genera, and in doing so we resurrect the genus Plesiosuchus for the species Dakosaurus manselii. Both species are diagnosed with numerous autapomorphies. Dakosaurus maximus has premaxillary 'lateral plates'; strongly ornamented maxillae; macroziphodont dentition; tightly fitting tooth-to-tooth occlusion; and extensive macrowear on the mesial and distal margins. Plesiosuchus manselii is distinct in having: non-amblygnathous rostrum; long mandibular symphysis; microziphodont teeth; tooth-crown apices that lack spalled surfaces or breaks; and no evidence for occlusal wear facets. Our phylogenetic analysis finds Dakosaurus maximus to be the sister taxon of the South American Dakosaurus andiniensis, and Plesiosuchus manselii in a polytomy at the base of Geosaurini (the subclade of macrophagous metriorhynchids that includes Dakosaurus, Geosaurus and Torvoneustes). Conclusions/Significance: The sympatry of Dakosaurus and Plesiosuchus is curiously similar to North Atlantic killer whales, which have one larger 'type' that lacks tooth-crown breakage being sympatric with a smaller 'type' that has extensive crown breakage. Assuming this morphofunctional complex is indicative of diet, then Plesiosuchus would be a specialist feeding on other marine reptiles while Dakosaurus would be a generalist and possible suction-feeder. This hypothesis is supported by Plesiosuchus manselii having a very large optimum gape (gape at which multiple teeth come into contact with a prey-item), while Dakosaurus maximus possesses craniomandibular characteristics observed in extant suction-feeding odontocetes: shortened tooth-row, amblygnathous rostrum and a very short mandibular symphysis. We hypothesise that trophic specialisation enabled these two large-bodied species to coexist in the same ecosystem.Facultad de Ciencias Naturales y Muse

The history, systematics, and nomenclature of Thalattosuchia (Archosauria: Crocodylomorpha)

The use of more than one nomenclatural code is becoming increasingly common in some biological sub-disciplines. To minimize nomenclatural instability, we have decided to establish a higher level systematization for Thalattosuchia under both the International Code of Phylogenetic Nomenclature (‘PhyloCode’) and the International Code of Zoological Nomenclature (‘Zoological Code’). We undertook a series of phylogenetic analyses with an expanded dataset to examine the origins of Thalattosuchia within Crocodylomorpha, and determined the clade’s diagnostic characters. Based on these analyses, we provide updated diagnoses for Thalattosuchia and its subclades under both the PhyloCode and Zoological Code. We also introduce two new nomina that are regulated under the PhyloCode (Neothalattosuchia and Euthalattosuchia), and the nomen Dakosaurina, which is registered under both nomenclatural codes. Moreover, we introduce PhyloCode-compliant phylogenetic definitions for Thalattosuchia and its subclades. As we cannot reliably discriminate between the positional hypotheses for Thalattosuchia within Crocodylomorpha, the clades’ origins are as much of a mystery today as they were over a century ago. However, we hope that using the same diagnostic characters to define the same clades, with the same nomina, under both nomenclatural codes will be an example to others to follow

The cranial osteology and feeding ecology of the Metriorhynchid Crocodylomorph Genera <i>Dakosaurus</i> and <i>Plesiosuchus</i> from the late Jurassic of Europe

Background: Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodied, macrophagous metriorhynchid crocodylomorphs. Recent studies show that these genera were apex predators in marine ecosystems during the latter part of the Late Jurassic, with robust skulls and strong bite forces optimized for feeding on large prey. Methodology/Principal Findings: Here we present comprehensive osteological descriptions and systematic revisions of the type species of both genera, and in doing so we resurrect the genus Plesiosuchus for the species Dakosaurus manselii. Both species are diagnosed with numerous autapomorphies. Dakosaurus maximus has premaxillary 'lateral plates'; strongly ornamented maxillae; macroziphodont dentition; tightly fitting tooth-to-tooth occlusion; and extensive macrowear on the mesial and distal margins. Plesiosuchus manselii is distinct in having: non-amblygnathous rostrum; long mandibular symphysis; microziphodont teeth; tooth-crown apices that lack spalled surfaces or breaks; and no evidence for occlusal wear facets. Our phylogenetic analysis finds Dakosaurus maximus to be the sister taxon of the South American Dakosaurus andiniensis, and Plesiosuchus manselii in a polytomy at the base of Geosaurini (the subclade of macrophagous metriorhynchids that includes Dakosaurus, Geosaurus and Torvoneustes). Conclusions/Significance: The sympatry of Dakosaurus and Plesiosuchus is curiously similar to North Atlantic killer whales, which have one larger 'type' that lacks tooth-crown breakage being sympatric with a smaller 'type' that has extensive crown breakage. Assuming this morphofunctional complex is indicative of diet, then Plesiosuchus would be a specialist feeding on other marine reptiles while Dakosaurus would be a generalist and possible suction-feeder. This hypothesis is supported by Plesiosuchus manselii having a very large optimum gape (gape at which multiple teeth come into contact with a prey-item), while Dakosaurus maximus possesses craniomandibular characteristics observed in extant suction-feeding odontocetes: shortened tooth-row, amblygnathous rostrum and a very short mandibular symphysis. We hypothesise that trophic specialisation enabled these two large-bodied species to coexist in the same ecosystem.Facultad de Ciencias Naturales y Muse

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

The Evolution of Mesoeucrocodylia (Crurotarsi, Crocodylomorpha) from Jurassic to Cretaceous : a phylogenetic review with emphasis on Gondwanan taxa

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Revisão sistemática e taxonômica dos Notosuchia (Metasuchia, Crocodylomorpha)

O presente trabalho aborda a Sistemática da Infra-Ordem Notosuchia, sob o ponto de vista filogenético, buscando alternativas que possam contribuir para a Taxonomia do grupo. Uma revisão de materiais reúne infomações paleontológicas, geológicas e biocronológicas para espécies e formas caracterizadas como parte do clado. Materiais inéditos são descritos para Mariliasuchus amarali e Notosuchus terrestris, permitindo uma melhor compreensão de aspectos morfo-anatômicos, evolutivos e paleoecológicos destas espécies. O Gênero Uruguaysuchus é reavaliado com relação a validade de materiais e sua composição. Restos referentes a uma nova espécie de crocodilomorfo notossuquiano são descritos e posicionados filogeneticamente. Análise filogenética foi conduzida para 24 taxons, com o uso de 179 caracteres, resultando em 14 árvores igualmente parcimoniosas, com Parcimônia de Fitch, bem como 4 árvores mais parcimoniosas para a aplicação de Parcimônia de Wagner à 26 séries de ordenação. Os resultados permitiram, entre outros aspectos: (a) a identificação de nova espécie de crocodilomorfo notossuquiano como grupo-irmão de Sphagesaurus huenei; (b) a confirmação da posição filogenética de Mariliasuchus e seu status como Notosuchidae; (c) a caracterização de Notosuchia como grado; (d) a sugestão de descrição em uma nova superfamília e uma nova infraordem no âmbito dos Metasuchia. Análise filogenética adicional, a partir de adaptação da metodologia formal, permitiu a reavaliação da posição filogenética de Chimaerasuchus paradoxus em relação a outros Crocodylomorpha e o estabelecimento de previsões de caráter evolutivo, anatômico e biocronológico.The present study approaches the systematic of the Infra-Order Notosuchia, under the scope of phylogenetics, searching for taxonomic propositions. A revision of the material gathers informations on Paleontology, Geology and Biocronology related to Notosuchia. Unpublished specimens from both Mariliasuchus amarali and Notosuchus terrestris are described, allowing a better comprehension of morpho-anatomic, evolutionary and paleoecological aspects concerning these species. The Genus Uruguaysuchus is revised on the validity of some materials and its composition. Unpublished data on a new notosuchian crocodylomorph species are described and its phylogenetic position is discussed. Phylogenetic analysis was conducted for 24 taxa, with the use of 179 characters, resulting in 14 equally parsimonious trees with the use of Fitchþs Parsimony, just like four equally parsimonious trees with the use of Wagnerþs Parsimony for 26 characters. The results allowed, among other aspects: (a) assigning the new notosuchian crocodylomorph species as the sister-group of Sphagesaurus huenei; (b) to corroborate Mariliasuchus as a Notosuchidae; (c) to understand Notosuchia as a grade; (d) the suggestion of a new superfamily and a new infraorder among metasuchian crocodylomorphs. Aditional phylogenetial analysis, with modifications to the original methodology, allowed a reevaluation of the phylogenetic position of Chimaerasuchus paradoxus within other groups of Crocodylomorpha and the construction of evolutive, anatomical and biocronologic previsions.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

A new Sphagesaurus (Mesoeucrocodylia: Notosuchia) from the Upper Cretaceous of Monte Alto City (Bauru Group, Brazil), and a revision of the Sphagesauridae

Since the description of Sphagesaurus, mostly dental material has been reported, apart from two incomplete skulls. Here we describe a new species of Sphagesaurus, from Monte Alto City, Southeastern Brazil, which includes the skull and most of the mandible. Distinctive characters (e. g. antorbital fenestra; robust quadrate; anterior mandibular teeth incisiform; ornamented sulcate palate) allow differentiation from S. huenei. Several characters allow assignment to the genus Sphagesaurus (e. g. teardrop-like oblique molariform teeth), while new information is provided (e. g. premaxilla, pterygoid and mandible morphology; jugal foramen; occipital surface; battery of mandibular teeth). A revision of the Family Sphagesauridae Kuhn 1968 is given. A preliminary phylogenetic analysis supports a sister-taxon relationship for S. huenei and the new species. The phylogenetic relationship of notosuchians is explored. Sphagesaurids were terrestrial notosuchians that evolved during the Upper Cretaceous of South America, known only from the Adamantina Formation, Campanian-Maastrichtian (Upper Cretaceous) from Brazil.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Morphological and anatomical observations about Mariliasuchus amarali and Notosuchus terrestris (Mesoeucrocodylia) and their relationships with other South American notosuchians.

The phylogenetic relationship of the notosuchians Mariliasuchus amarali (Campanian; Bauru Group) and Notosuchus terrestris (Santonian; Neuquen Group) is revised. Morpho-anatomical evaluation of Mariliasuchus in the current bibliography indicate close relationship with Notosuchus, while cladistic analysis either related Mariliasuchus to Candidodon itapecuruense (Albian/eo-Cenomanian; Sao Luis-Grajau Basin), as part of the phylotaxon Candidodontidae, or to Comahuesuchus brachybuccalis (Santonian; Neuquen Group). Comparative study of specimens shows similarities on the palate, choanae, dentition, retroarticular process, and other structures from Mariliasuchus and Notosuchus supporting the original classification as a Notosuchidae. Preliminary phylogenetic analysis sets these taxa as sister-groups. Reevaluation of a previously published phylogenetic analysis from other authors provides further support for the Mariliasuchus + Notosuchus clade. The current work indicates that Mariliasuchus is a Notosuchidae, refuting its allocation as a Candidodontidae. The influence of character construction and the definition of Notosuchia are discussed