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The ‘rotiferologist’ effect and other global correlates of species richness in monogonont rotifers
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The magnitude of global marine species diversity.
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The question of how many marine species exist is important because it provides a metric for how much we do and do not know about life in the oceans. We have compiled the first register of the marine species of the world and used this baseline to estimate how many more species, partitioned among all major eukaryotic groups, may be discovered.
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Chapter 2. Systematics and paleobiogeography of early bats
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no abstract
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Chapter 33. Reassessment of the Posterior Brain Region in Multituberculate Mammals
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Towards a Global Phylogeny of the "Living Fossil" Crustacean Order of the Notostraca
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First evidence of reproductive adaptation to “Island effect” of a dwarf Cretaceous Romanian titanosaur, with embryonic integument in ovo
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Background: The Cretaceous vertebrate assemblages of Romania are famous for geographically endemic dwarfed dinosaur taxa. We report the first complete egg clutches of a dwarf lithostrotian titanosaur, from Totes¸ti, Romania, and its reproductive adaptation to the ‘‘island effect’’. Methodology/Findings: The egg clutches were discovered in sequential sedimentary layers of the Maastrichtian Saˆnpetru Formation, Totes¸ti. The occurrence of 11 homogenous clutches in successive strata suggests philopatry by the same dinosaur species, which laid clutches averaging four ,12 cm diameters eggs. The eggs and eggshells display numerous characters shared with the positively identified material from egg-bearing level 4 of the Auca Mahuevo (Patagonia,Argentina) nemegtosaurid lithostrotian nesting site. Microscopic embryonic integument with bacterial evidences was recovered in one egg. The millimeter-size embryonic integument displays micron size dermal papillae implying an early embryological stage at the time of death, likely corresponding to early organogenesis before the skeleton formation. Conclusions/Significance: The shared oological characters between the Hat¸eg specimens and their mainland relatives suggest a highly conservative reproductive template, while the nest decrease in egg numbers per clutch may reflect an adaptive trait to a smaller body size due to the ‘‘island effect’’. The combined presence of the lithostrotian egg and its embryo in the Early Cretaceous Gobi coupled with the oological similarities between the Hat¸eg and Auca Mahuevo oological material evidence that several titanosaur species migrated from Gondwana through the Hat¸eg Island before or during the Aptian/Albian. It also suggests that this island might have had episodic land bridges with the rest of the European archipelago and Asia deep into the Cretaceous.
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Reappraisal of the morphology and phylogenetic relationships of the middle Eocene alligatoroidDiplocynodondeponiae (Frey, Laemmert and Riess, 1987) based on a 3D-prepared specimen
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We describe a three-dimensionally prepared specimen of Baryphracta deponiae from the middle Eocene of Messel (Darmstadt, Germany). Based on a phylogenetic analysis that included the addition of 20 novel scorings for characters previously unavailable for this taxon and the recoding of four additional characters, we found B. deponiae to be nested within Diplocynodon.We propose the new combination Diplocynodon deponiae. The name Baryphracta is thus a junior synonym of Diplocynodon. The small species D. deponiae (∼1 m in total length) shares several features with other species of Diplocynodon, including the presence of two subequal alveoli in the maxilla and dentary, exclusion of the splenial from the symphysis, and the shape of the iliac blade. However, it also differs in a few characters, including the presence of molariform teeth and the extension of osteoderms along the limbs and tail. Such osteodermal cover, which developed very early in ontogeny, easily distinguishes even small-sized specimens of D. deponiae from the co-occurring Diplocynodon darwini. The crocodylian fauna of Messel shows an astonishing diversity including at least seven taxa, with two belonging to the same genus. The two congeners exhibit differences in dentition and size that likely allowed for niche partitioning that minimized competition, thereby allowing them to be syntopic.
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Reassessment of the Morphology and Taxonomic Status of the earliest Herpetotheriid Marsupials of Europe
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The earliest Eocene locality of Dormaal (Belgium) has provided the oldest Cenozoic herpetotheriid marsupials of Europe. No herpetotheriid has ever been reported earlier than the Eocene in Europe, except for a questionable single upper molar from the Upper Cretaceous of the Belgian/Dutch border. The systematics of the herpetotheriids of Dormaal was formerly based on only a dozen dental specimens, which were assigned, after several revisions, to two species Peratherium constans and Amphiperatherium brabantense. Most importantly, these two species were considered at the root of most of the hepetotheriid lineages of the European Paleogene. Here we report a large sample of about 400 new dental remains that allow a better definition of both species as well as a testing of their systematic status. The evidence of significant morphological variability leads us to reconsider the diagnosis of Peratherium constans and to question the validity of Amphiperatherium brabantense. This study highlights that the primitive species Peratherium constans and Amphiperatherium brabantense are hardly distinguishable from each other, and therefore conclude that Peratherium constans was the only marsupial present at Dormaal. The important morphological variation exhibited by this herpetotheriid is similar to the variability observed in the type-species Peratherium elegans and in other fossil and extant metatherians. Consequently, our results suggest that several Amphiperatherium species from the Eocene could represent variants of the genus Peratherium. The question of the Amphiperatherium presence in Europe is therefore raised and a thorough discriminate analysis of both genera should be conducted in later works.
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Phylogenetic affinities and taxonomic composition of the Oligocene Diomedeoididae, and the basal divergences among extant Procellariiformes (Aves)
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The Palaeogene Diomedeoididae are amongst the earliest representatives of procellariiform birds (albatrosses, tubenoses, and allies). Although several fossils of these birds have been reported in the past, many details of their osteology remained unknown. Here we describe a comprehensive collection of diomedeoidid fossils from the Rupelian stratotype in Belgium, which was found more than 100 years ago. The material includes all major limb elements as well as other cranial and postcranial bones, and allows the recognition of previously unknown features of phylogenetic significance. Based on these new osteological data, diomedeoidids were for the first time subjected to a phylogenetic analysis, which resulted in a position outside a clade including Hydrobatidae (northern storm-petrels), Pelecanoididae (diving-petrels), and Procellariidae (fulmars, petrels, shearwaters, and allies), either as the sister taxon of Diomedeidae (albatrosses) or as that of all crown group Procellariiformes. The latter placement is better supported by the osteological evidence, and diomedeoidids lack several apomorphies of crown group Procellariiformes. Previously unrecognized derived features are reported that support a monophyletic Hydrobatidae, thus contradicting recent proposals that Oceanitinae (southern storm-petrels) are the earliest diverging crown group Procellariiformes. The new fossils also have a bearing on the convoluted taxonomy of diomedeoidids, and Diomedeoides Fischer, 1985 is synonymized with Rupelornis van Beneden, 1871. Diomedeoides lipsiensis (Fischer, 1983) is synonymous with Rupelornis definitus (van Beneden, 1871), a species that exhibits a large size range.
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The earliest Eocene mammal fauna of the Erquelinnes Sand Member near the French-Belgian border
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The earliest Eocene Erquelinnes site was discovered in 1880, but its mammal fauna has been frequently ignored. This paper provides the first detailed overview of the Erquelinnes mammals since 1929. The new faunal list doubles the known diversity at Erquelinnes to a total of 16 species, now also including amphilemurids, hyaenodontids, mesonychids, louisinids, equids and diacodexeids. The majority of the Erquelinnes species is also present in the earliest Eocene Dormaal MP7 reference fauna, with as most notable exceptions the presence of a potentially dwarfed specimen of Dissacus, and of two perissodactyl taxa at Erquelinnes. The ceratomorph perissodactyl Cymbalophus cuniculus is also known from the earliest Eocene of England, but a specimen identified as cf. Sifrhippus sandrae is closely similar to contemporaneous primitive North American equids. This specimen represents the oldest unambiguous European equid and highlights faunal similarities between Europe and North America during this time interval. Faunal differences between Erquelinnes and Dormaal seem mostly due to depositional differences, and the Erquelinnes fauna represents a typical earliest Eocene fauna, closely similar to other MP7 and PEI faunas in Europe.
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