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Brawn before brains in placental mammals after the end-Cretaceous extinction
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Mammals are the most encephalized vertebrates, with the largest brains relative to body size. Placental mammals have particularly enlarged brains, with expanded neocortices for sensory integration, the origins of which are unclear. We used computed tomography scans of newly discovered Paleocene fossils to show that contrary to the convention that mammal brains have steadily enlarged over time, early placentals initially decreased their relative brain sizes because body mass increased at a faster rate. Later in the Eocene, multiple crown lineages independently acquired highly encephalized brains through marked growth in sensory regions. We argue that the placental radiation initially emphasized increases in body size as extinction survivors filled vacant niches. Brains eventually became larger as ecosystems saturated and competition intensified.
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RBINS Staff Publications 2022 OA
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A new gecko from the earliest Eocene of Dormaal, Belgium: a thermophilic element of the ‘greenhouse world’
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We here describe a new gekkotan lizard from the earliest Eocene (MP 7) of the Dormaal locality in Belgium, from the time of the warmest global climates of the past 66 million years (Myr). This new taxon, with an age of 56 Myr, together with indeterminate gekkotan material reported from Silveirinha (Portugal, MP 7) represent the oldest Cenozoic gekkotans known from Europe. Today gekkotan lizards are distributed worldwide in mainly warm temperate to tropical areas and the new gecko from Dormaal represents a thermophilic faunal element. Given the Palaeocene–Eocene thermal maximum at that time, the distribution of this group in such northern latitudes (above 50° North – the latitude of southern England) is not surprising. Although this new gekkotan is represented only by a frontal (further, dentaries and a mandibular fragment are described here as Gekkota indet. 1 and 2—at least two gekkotan species occurred in Dormaal), it provides a new record for squamate diversity from the earliest Eocene ‘greenhouse world’. Together with the Baltic amber gekkotan Yantarogekko balticus, they document the northern distribution of gekkotans in Europe during the Eocene. The increase in temperature during the early Eocene led to a rise in sea level, and many areas of Eurasia were submerged. Thus, the importance of this period is magnified by understanding future global climate change.
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RBINS Staff Publications 2022 OA
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Revision of the oldest varanid, Saniwa orsmaelensis Dollo, 1923, from the earliest Eocene of northwest Europe
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Saniwa is an extinct genus of varanid squamate from the Eocene of North America and Europe. Up to now, only one poorly known species, Saniwa orsmaelensis Dollo, 1923, has been reported from Europe. Diagnostic material was limited to vertebrae with only preliminary description and no figure provided, except of one dorsal vertebra that was designated as the lectotype. New specimens from the earliest Eocene of Dormaal, Belgium and Le Quesnoy, France, including recently recovered skull ma-terial, are described and illustrated here. These fossils representing the oldest varanid squamate allow further comparisons with the type species, Saniwa ensidens Leidy, 1870, from the early and middle Eocene of North America and to propose a new diagnosis for S. orsmaelensis. Its arrival in Europe is probably linked to rapid environmental changes around the Paleocene Eocene Thermal Maximum (PETM). The occurrence of S. orsmaelensis is restricted to the early Eocene of northwest Europe and paleogeographic considerations regarding the distribution of the genus Saniwa Leidy, 1870 suggest an Asian origin, but an African origin cannot be completely excluded.
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RBINS Staff Publications 2022 OA
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Microphthalma europaea Egger, 1860 (Diptera: Tachinidae), un diptero endoparasito de Calicnemis obesa (Erichson, 1841) (Coleoptera: Scarabaeidae: Dynastinae) en Cadiz. Espana
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RBINS collections by external author(s)
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On the identity and status of Darala lineosa (Lepidoptera: Eupterotidae)
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RBINS collections by external author(s)
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The importance of correct labelling of types: an example in Tortricidae (Lepidoptera) and its rectification
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RBINS collections by external author(s)
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The tempo of cetacean cranial evolution
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RBINS Staff Publications 2022
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Three new species of Muricidae (Ocenebrinae, Pagodulinae) from the Gulf of California, Mexico and update of the living muricids from the area
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RBINS Staff Publications 2020
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Description of a new species of the genus Prionus Geoffroy, 1762 from northern Vietnam (Coleoptera: Cerambycidae: Prioninae)
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RBINS Staff Publications 2019
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New fossils, systematics, and biogeography of the oldest known crown primate Teilhardina from the earliest Eocene of Asia, Europe, and North America
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Omomyiform primates are among the most basal fossil haplorhines, with the oldest classified in the genus Teilhardina and known contemporaneously from Asia, Europe, and North America during the PaleoceneeEocene Thermal Maximum (PETM) ~56 mya. Characterization of morphology in this genus has been limited by small sample sizes and fragmentary fossils. A new dental sample (n ¼ 163) of the North American species Teilhardina brandti from PETM strata of the Bighorn Basin, Wyoming, documents previously unknown morphology and variation, prompting the need for a systematic revision of the genus. The P4 of T. brandti expresses a range of variation that encompasses that of the recently named, slightly younger North American species ‘Teilhardina gingerichi,’ which is here synonymized with T. brandti. A new partial dentary preserving the alveoli for P1-2 demonstrates that T. brandti variably expresses an unreduced, centrally-located P1, and in this regard is similar to that of T. asiatica from China. This observation, coupled with further documentation of variability in P1 alveolar size, position, and presence in the European type species T. belgica, indicates that the original diagnosis of T. asiatica is insufficient at distinguishing this species from either T. belgica or T. brandti. Likewise, the basal omomyiform ‘Archicebus achilles’ requires revision to be distinguished from Teilhardina. Results from a phylogenetic analysis of 1890 characters scored for omomyiforms, adapiforms, and other euarchontan mammals produces a novel clade including T. magnoliana, T. brandti, T. asiatica, and T. belgica to the exclusion of two species previously referred to Teilhardina, which are here classified in a new genus (Bownomomys americanus and Bownomomys crassidens). While hypotheses of relationships and inferred biogeographic patterns among species of Teilhardina could change with the discovery of more complete fossils, the results of these analyses indicate a similar probability that the genus originated in either Asia or North America.
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RBINS Staff Publications 2019